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Sample records for spotted alfalfa aphid

  1. Spotted alfalfa aphid, Therioaphis trifolii (Monell) (Hemiptera: Aphididae): Pest on alfalfa in Serbia

    OpenAIRE

    Jovičić, Ivana; Radonjić, Anđa; Petrović-Obradović, Olivera

    2017-01-01

    Spotted alfalfa aphid Therioaphis trifolii (Monell) (Hemiptera, Aphididae) is one of the most important alfalfa pest on the world. Also, it is the most abundant alfalfa aphid in Serbia. This aphid cause damage to alfalfa directly by feeding and indirectly by vectoring plant-pathogenic viruses. Some notes of morphology, host plants, damage, biology, vector role and distribution of spotted alfalfa aphid are given. Abundance of this aphid on alfalfa, influence of climates changes on its abundanc...

  2. Characterization and genetic dissection of resistance to spotted alfalfa aphid (Therioaphis trifolii) in Medicago truncatula

    KAUST Repository

    Kamphuis, L. G.; Lichtenzveig, J.; Peng, K.; Guo, S.-M.; Klingler, John; Siddique, K. H. M.; Gao, L.-L.; Singh, K. B.

    2013-01-01

    Aphids cause significant yield losses in agricultural crops worldwide. Medicago truncatula, a model legume, cultivated pasture species in Australia and close relative of alfalfa (Medicago sativa), was used to study the defence response against Therioaphis trifolii f. maculate [spotted alfalfa aphid (SAA)]. Aphid performance and plant damage were compared among three accessions. A20 is highly susceptible, A17 has moderate resistance, and Jester is strongly resistant. Subsequent analyses using A17 and A20, reciprocal F1s and an A17×A20 recombinant inbred line (RIL) population revealed that this moderate resistance is phloem mediated and involves antibiosis and tolerance but not antixenosis. Electrical penetration graph analysis also identified a novel waveform termed extended potential drop, which occurred following SAA infestation of M. truncatula. Genetic dissection using the RIL population revealed three quantitative trait loci on chromosomes 3, 6, and 7 involved in distinct modes of aphid defence including antibiosis and tolerance. An antibiosis locus resides on linkage group 3 (LG3) and is derived from A17, whereas a plant tolerance and antibiosis locus resides on LG6 and is derived from A20, which exhibits strong temporary tolerance. The loci identified reside in regions harbouring classical resistance genes, and introgression of these loci in current medic cultivars may help provide durable resistance to SAA, while elucidation of their molecular mechanisms may provide valuable insight into other aphid–plant interactions.

  3. Characterization and genetic dissection of resistance to spotted alfalfa aphid (Therioaphis trifolii) in Medicago truncatula

    KAUST Repository

    Kamphuis, L. G.

    2013-09-21

    Aphids cause significant yield losses in agricultural crops worldwide. Medicago truncatula, a model legume, cultivated pasture species in Australia and close relative of alfalfa (Medicago sativa), was used to study the defence response against Therioaphis trifolii f. maculate [spotted alfalfa aphid (SAA)]. Aphid performance and plant damage were compared among three accessions. A20 is highly susceptible, A17 has moderate resistance, and Jester is strongly resistant. Subsequent analyses using A17 and A20, reciprocal F1s and an A17×A20 recombinant inbred line (RIL) population revealed that this moderate resistance is phloem mediated and involves antibiosis and tolerance but not antixenosis. Electrical penetration graph analysis also identified a novel waveform termed extended potential drop, which occurred following SAA infestation of M. truncatula. Genetic dissection using the RIL population revealed three quantitative trait loci on chromosomes 3, 6, and 7 involved in distinct modes of aphid defence including antibiosis and tolerance. An antibiosis locus resides on linkage group 3 (LG3) and is derived from A17, whereas a plant tolerance and antibiosis locus resides on LG6 and is derived from A20, which exhibits strong temporary tolerance. The loci identified reside in regions harbouring classical resistance genes, and introgression of these loci in current medic cultivars may help provide durable resistance to SAA, while elucidation of their molecular mechanisms may provide valuable insight into other aphid–plant interactions.

  4. Alfalfa (Medicago sativa L.) shoot saponins: identification and bio-activity by the assessment of aphid feeding.

    Science.gov (United States)

    Mazahery-Laghab, H; Yazdi-Samadi, B; Bagheri, M; Bagheri, A R

    2011-01-01

    Biochemical components in alfalfa (Medicago sativa L.), such as saponins, can act as protecting factors against bio-stresses. Saponins are also antifeedants and show oral toxicity towards higher and lower animals. Changes in saponins, such as variation in the carbon skeleton, or hydrolysis of saponin glycosides and other conjugates, may change their biological effects. The aims of this research were to study saponin variation in different growth stages of alfalfa and to investigate the biological role of saponins in the spotted alfalfa aphid, Therioaphis maculata. Saponins from alfalfa shoots in different growth stages were extracted, chemically purified and analysed by TLC. Specific saponins such as soyasaponin1 from root and shoot and two bisdesmosides of medicagenic acid, one from shoot and another from root tissues, were identified using reference compounds allowing changes in saponin composition during plant development in different shoot tissues of alfalfa to be assessed. The response of the alfalfa aphid to feeding on alfalfa in different growth stages was studied. No significant difference in the survival of aphids, from neonate to adult, was observed, but due to the antibiotic effects of saponins, two differences were found in the onset of nymph production and cumulative nymph production. The results show that the saponin composition in alfalfa changes with plant development and this, in turn, can often negatively affect the development of specific insect pests such as the spotted alfalfa aphid, suggesting a possible biological role of alfalfa saponins.

  5. Aphids and ladybird beetle’s abundance and diversity in alfalfa fields of Yasouj, southwestern of Iran

    Directory of Open Access Journals (Sweden)

    S. Mirfakhraie

    2017-12-01

    Full Text Available Alfalfa (Medicago sativa L. is the oldest and the most important forage legume. It has been cultivated for forage longer than any other crop. Diversity indices provide information about community composition. Diversity indices are measured by species richness and species evenness therefore, it could give us more ecological information rather than a simple species list in the fields. During 2015-2016, aphids and ladybird beetle’s abundance and diversity were monitored in alfalfa fields of Yasouj. Samplings were conducted with 150 plants in the alfalfa fields from mid-May to mid-November. Species richness was measured using Shannon and Simpson indices. In this study, six aphids and five coccinellid species were collected and identified. Among the collected aphid species, Aphis fabae (Scopoli, 1763 and Therioaphis maculata (Buckton, 1899 were most abundant in the fields. For coccinellids, Coccinella septempunctata L. was the most abundant species. Highest aphid species diversity was observed on 17 May 2016.

  6. Resistance and susceptibility of alfalfa (Medicago sativa L.) cultivars to the aphid Therioaphis maculata (Homoptera:Aphididae): insect biology and cultivar evaluation

    Institute of Scientific and Technical Information of China (English)

    ALEXANDRE DE ALMEIDA E SILVA; ELENICE MOURO VARANDA; JOS(E) RICARDO BAROSELA

    2006-01-01

    Biology of the aphid Therioaphis maculata was studied on alfalfa (Medicago sativa L.), including four resistant (Mesa-Sirsa, CUF101, Baker and Lahontan) and two susceptible (ARC and Caliverde) alfalfa cultivars, and one of the most cropped Brazilian cultivars, Crioula. Under controlled conditions, antibiosis (i.e., reduced longevity, fecundity and increased mortality of the aphid) was observed mainly on the resistant alfalfa cultivars,except on Lahontan. Crioula seemed to be tolerant to aphids. Present data support geographic limitation usage of cultivars, and we suggest Baker and Mesa-Sirsa as sources of antibiosis,and provide biological information of a tropical T. maculata biotype on alfalfa.

  7. Alfalfa Leaf Curl Virus: an Aphid-Transmitted Geminivirus.

    Science.gov (United States)

    Roumagnac, Philippe; Granier, Martine; Bernardo, Pauline; Deshoux, Maëlle; Ferdinand, Romain; Galzi, Serge; Fernandez, Emmanuel; Julian, Charlotte; Abt, Isabelle; Filloux, Denis; Mesléard, François; Varsani, Arvind; Blanc, Stéphane; Martin, Darren P; Peterschmitt, Michel

    2015-09-01

    The family Geminiviridae comprises seven genera differentiated by genome organization, sequence similarity, and insect vector. Capulavirus, an eighth genus, has been proposed to accommodate two newly discovered highly divergent geminiviruses that presently have no known vector. Alfalfa leaf curl virus, identified here as a third capulavirus, is shown to be transmitted by Aphis craccivora. This is the first report of an aphid-transmitted geminivirus. Copyright © 2015, American Society for Microbiology. All Rights Reserved.

  8. Stem nematode counteracts plant resistance of aphids in alfalfa, Medicago sativa.

    Science.gov (United States)

    Ramirez, Ricardo A; Spears, Lori R

    2014-10-01

    Plants are exploited by a diverse community of insect herbivores and phytopathogens that interact indirectly through plant-mediated interactions. Generally, plants are thought to respond to insects and pathogens through different defensive signaling pathways. As plants are selected for resistance to one phytophagous organism type (insect vs. pathogen) in managed systems, it is not clear how this selection may affect community interactions. This study examined the effect of nematode-resistant varieties on aphid (Acyrthosiphon pisum) suppression, and then determined how infection by the stem nematode, Ditylenchus dipsaci, mediated ecological effects on aphids and on plant defense proteins. Four alfalfa (Medicago sativa) varieties were selected with resistance to nematodes only (+,-), aphids only (-,+), nematodes and aphids (+,+), and susceptibility to nematodes and aphids (-,-). Field and greenhouse experiments were conducted to isolate the effect of nematode infection and aphid abundance on each variety. We found that varieties resistant to nematode, regardless of aphid resistance, had the lowest aphid counts, suggesting possible cross-resistance. Aphid abundance, however, increased when plants were exposed to nematodes. Resistant varieties were associated with elevated saponins but these compounds were not affected by insect or pathogen feeding. Concentrations of peroxidases and trypsin inhibitors, however, were increased in nematode resistant varieties when exposed to nematodes and aphids, respectively. The patterns of plant defense were variable, and a combination of resistance traits and changes in nutrient availability may drive positive interactions between nematodes and aphids aboveground.

  9. Predation determines different selective pressure on pea aphid host races in a complex agricultural mosaic.

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    Adalbert Balog

    Full Text Available Field assessments were conducted to examine the interplay between host plant and predation in complex agricultural mosaic on pea aphid clover and alfalfa races. In one experiment, we examined the relative fitness on clover race (CR and alfalfa race (AR pea aphids on broad bean, red clover and alfalfa alone. But because clover is typically grown in a more complex agricultural mosaic with alfalfa and broad bean, a second experiment was conducted to assess the fitness consequences under predation in a more complex agricultural field setting that also included potential apparent competition with AR pea aphids. In a third experiment we tested for the effect of differential host race density on the fitness of the other host race mediated by a predator effect. CR pea aphids always had fitness losses when on broad bean (had lower fitness on broad bean relative to red clover and fitness benefits when on red clover (higher fitness on red clover relative to broad bean, whether or not in apparent competition with alfalfa race aphids on bean and alfalfa. AR suffered fitness loss on both alfalfa and bean in apparent competition with CR on clover. Therefore we can conclude that the predation rate between host races was highly asymmetrical. The complexity of the agricultural mosaic thus can influence prey selection by predators on different host plants. These may have evolutionary consequences through context dependent fitness benefits on particular host plants.

  10. Differential Life History Trait Associations of Aphids with Nonpersistent Viruses in Cucurbits.

    Science.gov (United States)

    Angelella, G M; Egel, D S; Holland, J D; Nemacheck, J A; Williams, C E; Kaplan, I

    2015-06-01

    The diversity of vectors and fleeting nature of virus acquisition and transmission renders nonpersistent viruses a challenge to manage. We assessed the importance of noncolonizing versus colonizing vectors with a 2-yr survey of aphids and nonpersistent viruses on commercial pumpkin farms. We quantified aphid alightment using pan traps, while testing leaf samples with multiplex RT-PCR targeting cucumber mosaic virus (CMV), zucchini yellow mosaic virus (ZYMV), watermelon mosaic virus (WMV), and papaya ringspot virus (PRSV). Overall, we identified 53 aphid species (3,899 individuals), from which the melon aphid, Aphis gossypii Glover, a pumpkin-colonizing species, predominated (76 and 37% of samples in 2010 and 2011, respectively). CMV and ZYMV were not detected, but WMV and PRSV were prevalent, both regionally (WMV: 28/29 fields, PRSV: 21/29 fields) and within fields (infection rates = 69 and 55% for WMV in 2010 and 2011; 28 and 25% for PRSV in 2010 and 2011). However, early-season samples showed extremely low infection levels, suggesting cucurbit viruses are not seed-transmitted and implicating aphid activity as a causal factor driving virus spread. Interestingly, neither noncolonizer and colonizer alightment nor total aphid alightment were good predictors of virus presence, but community analyses revealed species-specific relationships. For example, cowpea aphid (Aphis craccivora Koch) and spotted alfalfa aphid (Therioaphis trifolii Monell f. maculata) were associated with PRSV infection, whereas the oleander aphid (Aphis nerii Bover de Fonscolombe) was associated with WMV spread within fields. These outcomes highlight the need for tailored management plans targeting key vectors of nonpersistent viruses in agricultural systems. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. Association mapping of aphid resistance in USDA cowpea (Vigna unguiculata L. Walp.) core collection using SNPs

    Science.gov (United States)

    Cowpea aphid (CPA; Aphis craccivora) is a destructive insect pest of cowpea, as well as other legume crops including alfalfa, beans, chickpea, lentils, lupins and peanuts. The utilization of aphid resistance in cowpea breeding is one of the most efficient and environmental friendly methods to contro...

  12. Proteomic investigation of aphid honeydew reveals an unexpected diversity of proteins.

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    Ahmed Sabri

    Full Text Available Aphids feed on the phloem sap of plants, and are the most common honeydew-producing insects. While aphid honeydew is primarily considered to comprise sugars and amino acids, its protein diversity has yet to be documented. Here, we report on the investigation of the honeydew proteome from the pea aphid Acyrthosiphon pisum. Using a two-Dimensional Differential in-Gel Electrophoresis (2D-Dige approach, more than 140 spots were isolated, demonstrating that aphid honeydew also represents a diverse source of proteins. About 66% of the isolated spots were identified through mass spectrometry analysis, revealing that the protein diversity of aphid honeydew originates from several organisms (i.e. the host aphid and its microbiota, including endosymbiotic bacteria and gut flora. Interestingly, our experiments also allowed to identify some proteins like chaperonin, GroEL and Dnak chaperones, elongation factor Tu (EF-Tu, and flagellin that might act as mediators in the plant-aphid interaction. In addition to providing the first aphid honeydew proteome analysis, we propose to reconsider the importance of this substance, mainly acknowledged to be a waste product, from the aphid ecology perspective.

  13. Evaluation of airborne methyl salicylate for improved conservation biological control of two-spotted spider mite and hop aphid in Oregon hop yards.

    Science.gov (United States)

    Woods, J L; James, D G; Lee, J C; Gent, D H

    2011-12-01

    The use of synthetic herbivore-induced plant volatiles (HIPV) to attract natural enemies has received interest as a tool to enhance conservation biological control (CBC). Methyl salicylate (MeSA) is a HIPV that is attractive to several key predators of two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), and hop aphid, Phorodon humuli (Schrank) (Homoptera: Aphididae). A 2-year study was conducted to evaluate the recommended commercial use of MeSA in hop yards in Oregon. Slow-release MeSA dispensers were stapled to supporting poles in 0.5 ha plots and these plots were compared to a paired non-treated plot on each of three farms in 2008 and 2009. Across both years, there was a trend for reduced (range 40-91%) mean seasonal numbers of T. urticae in five of the six MeSA-baited plots. Stethorus spp., key spider mite predators, tended to be more numerous in MeSA-baited plots compared to control plots on a given farm. Mean seasonal densities of hop aphid and other natural enemies (e.g., Orius spp. and Anystis spp.) were similar between MeSA-treated and control plots. Variability among farms in suppression of two-spotted spider mites and attraction of Stethorus spp. suggests that the use of MeSA to enhance CBC of spider mites in commercial hop yards may be influenced by site-specific factors related to the agroecology of individual farms or seasonal effects that require further investigation. The current study also suggests that CBC of hop aphid with MeSA in this environment may be unsatisfactory.

  14. Occurrence, Distribution and Properties of Alfalfa Mosaic Virus

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    A.D. Zadjaii

    2002-01-01

    Full Text Available Alfalfa Mosaic Virus (AlflMV was recorded on 21 hosts comprising of four field crops, 14 vegetables, one ornamental plant and two new weed species (Heliotropium europaeum and Ammi majus belonging to nine families. The virus was identified and confirmed on the basis of its biological, serological (ELISA and physical properties. The leaves, stem and crown from systemically infected alfalfa plant contained high concentration of the virus. It was nonpersistently transmitted by cotton aphids (Aphis gossypii. The wide host range, including virus reservoirs, seed-borne infection and insect transmission account for high incidence and distribution of AlfMV in the country. The virus isolate had a dilution end point between 1 x 10-3 to l x 10-4, 65-67 °C thermal inactivation point and a few days in-vitro longevity and appears to be similar to the AlfMV-S strain.

  15. Biological control of tortricids and aphids in strawberries

    DEFF Research Database (Denmark)

    Sigsgaard, Lene; Enkegaard, Annie; Eilenberg, Jørgen

    Cropping practice and biological control can contribute to reduced pesticide use in strawberries. Organic strawberries are less attacked by strawberry tortricid and buckwheat flower strips can augment its natural enemies. Against shallot aphid the two-spot ladybird is promising....

  16. ALFALFA

    OpenAIRE

    Mirko Stjepanović; Robert Zimmer; Marijana Tucak; Gordana Bukvić; Svetislav Popović; Zvonimir Štafa

    2009-01-01

    The academic textbook Alfalfa contains the following chapters: Review outline, Foreword, Origin and spread of alfalfa, Economic importance of alfalfa, Biological properties and breeding alfalfa, Morphological traits of alfalfa, Growth and development of alfalfa, Ecological conditions for alfalfa growth, Agronomy of alfalfa for fodder production, Pests and diseases of alfalfa and their control, Usage of alfalfa and hay, silage and haylage production, Alfalfa seed production, Prospects for alfa...

  17. ALFALFA

    Directory of Open Access Journals (Sweden)

    Mirko Stjepanović

    2009-12-01

    Full Text Available The academic textbook Alfalfa contains the following chapters: Review outline, Foreword, Origin and spread of alfalfa, Economic importance of alfalfa, Biological properties and breeding alfalfa, Morphological traits of alfalfa, Growth and development of alfalfa, Ecological conditions for alfalfa growth, Agronomy of alfalfa for fodder production, Pests and diseases of alfalfa and their control, Usage of alfalfa and hay, silage and haylage production, Alfalfa seed production, Prospects for alfalfa in Croatia, Index and interpreter of terms and abbreviations, About authors. How to satisfy requirements of the “queen of fodder crops“ to achieve high yields of high quality fodder is the issue presented in the book Alfalfa is being grown in Croatia on about 42 000 hectares. Average fodder yields are low, about 5 t ha1, so the employment of genetical potential of varieties in rainfed farming is 35 to 40%, making the production more expensive.

  18. Shallot aphids, Myzus ascalonicus, in strawberry

    DEFF Research Database (Denmark)

    Enkegaard, Annie; Sigsgaard, Lene; Kristensen, Kristian

    2013-01-01

    The parasitization capacity of 3 parasitoids and the predation capacity of 3 predators towards the shallot aphid, Myzus ascalonicus Doncaster (Homoptera: Aphididae), on strawberry, Fragaria x ananassa Duchesne (Rosales: Rosaceae) cv. Honeoye, were examined in laboratory experiments. In Petri dish...... other parasitoid-induced causes. However, the host feeding rate was reduced to only 1.2 ± 0.8%, and no significant parasitization mortality was observed on strawberry plants, suggesting that host plants interfered with A. abdominalis activity. This parasitoid does not, therefore, seem to be suited...... to either inoculative or inundative biocontrol of shallot aphids in strawberry. The three predators studied were the green lacewing, Chrysoperla carnea Steph. (Neuroptera: Chrysopi-dae), the two-spotted lady beetle, Adalia bipunctata L. (Coleoptera: Coccinellidae), and the gall midge Aphidoletes aphidimyza...

  19. Identification of Alfalfa Leaf Diseases Using Image Recognition Technology.

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    Feng Qin

    Full Text Available Common leaf spot (caused by Pseudopeziza medicaginis, rust (caused by Uromyces striatus, Leptosphaerulina leaf spot (caused by Leptosphaerulina briosiana and Cercospora leaf spot (caused by Cercospora medicaginis are the four common types of alfalfa leaf diseases. Timely and accurate diagnoses of these diseases are critical for disease management, alfalfa quality control and the healthy development of the alfalfa industry. In this study, the identification and diagnosis of the four types of alfalfa leaf diseases were investigated using pattern recognition algorithms based on image-processing technology. A sub-image with one or multiple typical lesions was obtained by artificial cutting from each acquired digital disease image. Then the sub-images were segmented using twelve lesion segmentation methods integrated with clustering algorithms (including K_means clustering, fuzzy C-means clustering and K_median clustering and supervised classification algorithms (including logistic regression analysis, Naive Bayes algorithm, classification and regression tree, and linear discriminant analysis. After a comprehensive comparison, the segmentation method integrating the K_median clustering algorithm and linear discriminant analysis was chosen to obtain lesion images. After the lesion segmentation using this method, a total of 129 texture, color and shape features were extracted from the lesion images. Based on the features selected using three methods (ReliefF, 1R and correlation-based feature selection, disease recognition models were built using three supervised learning methods, including the random forest, support vector machine (SVM and K-nearest neighbor methods. A comparison of the recognition results of the models was conducted. The results showed that when the ReliefF method was used for feature selection, the SVM model built with the most important 45 features (selected from a total of 129 features was the optimal model. For this SVM model, the

  20. Identification of Alfalfa Leaf Diseases Using Image Recognition Technology

    Science.gov (United States)

    Qin, Feng; Liu, Dongxia; Sun, Bingda; Ruan, Liu; Ma, Zhanhong; Wang, Haiguang

    2016-01-01

    Common leaf spot (caused by Pseudopeziza medicaginis), rust (caused by Uromyces striatus), Leptosphaerulina leaf spot (caused by Leptosphaerulina briosiana) and Cercospora leaf spot (caused by Cercospora medicaginis) are the four common types of alfalfa leaf diseases. Timely and accurate diagnoses of these diseases are critical for disease management, alfalfa quality control and the healthy development of the alfalfa industry. In this study, the identification and diagnosis of the four types of alfalfa leaf diseases were investigated using pattern recognition algorithms based on image-processing technology. A sub-image with one or multiple typical lesions was obtained by artificial cutting from each acquired digital disease image. Then the sub-images were segmented using twelve lesion segmentation methods integrated with clustering algorithms (including K_means clustering, fuzzy C-means clustering and K_median clustering) and supervised classification algorithms (including logistic regression analysis, Naive Bayes algorithm, classification and regression tree, and linear discriminant analysis). After a comprehensive comparison, the segmentation method integrating the K_median clustering algorithm and linear discriminant analysis was chosen to obtain lesion images. After the lesion segmentation using this method, a total of 129 texture, color and shape features were extracted from the lesion images. Based on the features selected using three methods (ReliefF, 1R and correlation-based feature selection), disease recognition models were built using three supervised learning methods, including the random forest, support vector machine (SVM) and K-nearest neighbor methods. A comparison of the recognition results of the models was conducted. The results showed that when the ReliefF method was used for feature selection, the SVM model built with the most important 45 features (selected from a total of 129 features) was the optimal model. For this SVM model, the

  1. Genetic relationships among alfalfa gemplasms resistant to common ...

    African Journals Online (AJOL)

    Genetic relationships among 26 alfalfa cultivars, of which, 12 were of high resistance to common leaf spot (CLS), were assessed using sequence-related amplified polymorphism (SRAP) markers. 34 SRAP primer combinations were selected for fingerprinting of these cultivars and a total of 281 bands were observed, among ...

  2. Assessment of patch quality by aphidophagous ladybirds: laboratory study on the minimum density of aphids required for oviposition

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    B. C. Das

    2011-12-01

    Full Text Available Many studies indicate that there is a density of aphids below which ladybirds are unlikely to lay eggs. This is adaptive as theory indicates that a certain minimum population density of aphids is required if hatchling larvae are to survive. The responses of gravid females of the two spot ladybird, Adalia bipunctata (L. (Coleoptera: Coccinellidae, recorded over a period of an hour, to colonies of 5 and 50 pea aphids on bean plants and similar plants each previously infested with the same number of aphids for 48 hours were determined. Proportionally more of the ladybirds on plants with 50 aphids or that were previously infested with the same number of aphids for 48 hours laid eggs and larger clusters of eggs, and were less active than those on plants that were infested with or had previously been infested with five aphids. That is, gravid females showed similar oviposition and activity responses to aphid abundance and different levels of honeydew contamination. This indicates that honeydew contamination may be an important cue used by ladybirds when locating and assessing the abundance of prey in aphid colonies.

  3. Parasitoid complex of alfalfa aphids in an IPM intensive crop system in northern Catalonia

    Czech Academy of Sciences Publication Activity Database

    Pons, X.; Lumbierres, B.; Antoni, R.; Starý, Petr

    2011-01-01

    Roč. 84, č. 4 (2011), s. 437-445 ISSN 1612-4758 Grant - others:Universitat de Lleida(ES) CO8026; Universitat de Lleida(ES) CO9036 Institutional research plan: CEZ:AV0Z50070508 Keywords : alfalfa * Aphididae * Braconidae Subject RIV: EH - Ecology, Behaviour Impact factor: 1.509, year: 2011

  4. Alfalfa

    Science.gov (United States)

    Alfalfa is an herb. People use the leaves, sprouts, and seeds to make medicine. Alfalfa is used for kidney conditions, bladder and prostate ... bleeding disorder called thrombocytopenic purpura. People also take alfalfa as a source of vitamins A, C, E, ...

  5. Aphid alarm pheromone as a cue for ants to locate aphid partners.

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    François J Verheggen

    Full Text Available The mutualistic relationships that occur between myrmecophilous aphids and ants are based on the rich food supply that honeydew represents for ants and on the protection they provide against aphid natural enemies. While aphid predators and parasitoids actively forage for oviposition sites by using aphid semiochemicals, scouts of aphid-tending ant species would also benefit from locating honeydew resources by orienting toward aphid pheromone sources. The present study aims to provide additional information on the use of Aphis fabae alarm pheromone, i.e. (E-β-farnesene (EβF, by ant scouts. The perception and behavioral impact of EβF on Lasius niger were investigated using electroantennography and two bio-assays measuring their attraction and orientation towards aphid semiochemicals. Pronounced electrical depolarizations were observed from L. niger scout antennae to stimulations of A. fabae alarm pheromone, while other sesquiterpenes elicited weak or no responses. L. niger scouts were significantly attracted toward EβF in a four-arm olfactometer, as well as in an two-choice bioassay. These laboratory results suggest for the first time that low amounts of aphid alarm pheromone can be used by L. niger scouts as a cue indicating the presence of aphid colonies and could therefore mediate the aphid-ant partnership in the field.

  6. Ant Larval Demand Reduces Aphid Colony Growth Rates in an Ant-Aphid Interaction

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    James M. Cook

    2012-02-01

    Full Text Available Ants often form mutualistic interactions with aphids, soliciting honeydew in return for protective services. Under certain circumstances, however, ants will prey upon aphids. In addition, in the presence of ants aphids may increase the quantity or quality of honeydew produced, which is costly. Through these mechanisms, ant attendance can reduce aphid colony growth rates. However, it is unknown whether demand from within the ant colony can affect the ant-aphid interaction. In a factorial experiment, we tested whether the presence of larvae in Lasius niger ant colonies affected the growth rate of Aphis fabae colonies. Other explanatory variables tested were the origin of ant colonies (two separate colonies were used and previous diet (sugar only or sugar and protein. We found that the presence of larvae in the ant colony significantly reduced the growth rate of aphid colonies. Previous diet and colony origin did not affect aphid colony growth rates. Our results suggest that ant colonies balance the flow of two separate resources from aphid colonies- renewable sugars or a protein-rich meal, depending on demand from ant larvae within the nest. Aphid payoffs from the ant-aphid interaction may change on a seasonal basis, as the demand from larvae within the ant colony waxes and wanes.

  7. Ants defend aphids against lethal disease

    Science.gov (United States)

    Nielsen, Charlotte; Agrawal, Anurag A.; Hajek, Ann E.

    2010-01-01

    Social insects defend their own colonies and some species also protect their mutualist partners. In mutualisms with aphids, ants typically feed on honeydew produced by aphids and, in turn guard and shelter aphid colonies from insect natural enemies. Here we report that Formica podzolica ants tending milkweed aphids, Aphis asclepiadis, protect aphid colonies from lethal fungal infections caused by an obligate aphid pathogen, Pandora neoaphidis. In field experiments, bodies of fungal-killed aphids were quickly removed from ant-tended aphid colonies. Ant workers were also able to detect infective conidia on the cuticle of living aphids and responded by either removing or grooming these aphids. Our results extend the long-standing view of ants as mutualists and protectors of aphids by demonstrating focused sanitizing and quarantining behaviour that may lead to reduced disease transmission in aphid colonies. PMID:19923138

  8. Volatile communication in plant-aphid interactions.

    Science.gov (United States)

    de Vos, Martin; Jander, Georg

    2010-08-01

    Volatile communication plays an important role in mediating the interactions between plants, aphids, and other organisms in the environment. In response to aphid infestation, many plants initiate indirect defenses through the release of volatiles that attract ladybugs, parasitoid wasps, and other aphid-consuming predators. Aphid-induced volatile release in the model plant Arabidopsis thaliana requires the jasmonate signaling pathway. Volatile release is also induced by infection with aphid-transmitted viruses. Consistent with mathematical models of optimal transmission, viruses that are acquired rapidly by aphids induce volatile release to attract migratory aphids, but discourage long-term aphid feeding. Although the ecology of these interactions is well-studied, further research is needed to identify the molecular basis of aphid-induced and virus-induced changes in plant volatile release. Copyright 2010 Elsevier Ltd. All rights reserved.

  9. Effects of two alfalfa preparations with different particle sizes on the gastric mucosa in weanlings: alfalfa chaff versus alfalfa pellets

    OpenAIRE

    Vondran, Sarah; Venner, Monica; Vervuert, Ingrid

    2016-01-01

    Background Feeding alfalfa hay is often recommended for its buffering components, like protein and calcium, to prevent lesions of the gastric mucosa in horses. Until now, there has been no information regarding the influence of alfalfa particle size on the gastric mucosa. The aim of this study was to investigate the effects of feeding two alfalfa preparations with different particle sizes (alfalfa chaff vs alfalfa pellets) in comparison with grass hay on the gastric mucosa in weanling horses....

  10. Genetics coupled to quantitative intact proteomics links heritable aphid and endosymbiont protein expression to circulative polerovirus transmission.

    Science.gov (United States)

    Cilia, M; Tamborindeguy, C; Fish, T; Howe, K; Thannhauser, T W; Gray, S

    2011-03-01

    Yellow dwarf viruses in the family Luteoviridae, which are the causal agents of yellow dwarf disease in cereal crops, are each transmitted most efficiently by different species of aphids in a circulative manner that requires the virus to interact with a multitude of aphid proteins. Aphid proteins differentially expressed in F2 Schizaphis graminum genotypes segregating for the ability to transmit Cereal yellow dwarf virus-RPV (CYDV-RPV) were identified using two-dimensional difference gel electrophoresis (DIGE) coupled to either matrix-assisted laser desorption ionization-tandem mass spectrometry or online nanoscale liquid chromatography coupled to electrospray tandem mass spectrometry. A total of 50 protein spots, containing aphid proteins and proteins from the aphid's obligate and maternally inherited bacterial endosymbiont, Buchnera, were identified as differentially expressed between transmission-competent and refractive aphids. Surprisingly, in virus transmission-competent F2 genotypes, the isoelectric points of the Buchnera proteins did not match those in the maternal Buchnera proteome as expected, but instead they aligned with the Buchnera proteome of the transmission-competent paternal parent. Among the aphid proteins identified, many were involved in energy metabolism, membrane trafficking, lipid signaling, and the cytoskeleton. At least eight aphid proteins were expressed as heritable, isoelectric point isoform pairs, one derived from each parental lineage. In the F2 genotypes, the expression of aphid protein isoforms derived from the competent parental lineage aligned with the virus transmission phenotype with high precision. Thus, these isoforms are candidate biomarkers for CYDV-RPV transmission in S. graminum. Our combined genetic and DIGE approach also made it possible to predict where several of the proteins may be expressed in refractive aphids with different barriers to transmission. Twelve proteins were predicted to act in the hindgut of the aphid

  11. First report of Alfalfa mosaic virus infecting basil (Ocimum basilicum L.) in California.

    Science.gov (United States)

    Basil (Ocimum basilicum L.) plants collected from a field in Imperial County, CA in May, 2011 were found to exhibit yellowing, chlorotic sectors and spots on leaves, resulting in plants being unmarketable. Total nucleic acid was extracted from plants and tested by RT-PCR for the presence of Alfalfa...

  12. The impacts of climate change and belowground herbivory on aphids via primary metabolites

    Science.gov (United States)

    Ryalls, James M. W.

    Global climate and atmospheric change (summarised as climate change for brevity) may alter patterns of crop damage by insect herbivores, but little is known about how multiple climate change factors, acting in tandem, shape such interactions. Crucially, the specific plant-mediated mechanisms underpinning these effects remain largely unknown. Moreover, research into the effects of climate change on leguminous plant species, which have the ability to fix atmospheric nitrogen (N2) via their association with root nodule-dwelling rhizobial bacteria, and their associated insect herbivores, is surprisingly scarce considering their increasing importance in terrestrial ecosystems worldwide. Using a model legume, lucerne, otherwise known as alfalfa, Medicago sativa (Fabaceae), and a model pest species, the pea aphid, Acyrthosiphon pisum (Hemiptera: Aphididae), this work addresses how predicted changes in carbon dioxide (CO2) concentrations, temperature and rainfall patterns as well as interactions with other organisms, including the root-feeding weevil Sitona discoideus (Coleoptera: Curculionidae), might shape legume-feeding aphid populations in the future. Recent literature on the impacts of climate change on aphids and the biology and trophic interactions of lucerne aphids specifically were synthesised in chapters one and two, respectively. These chapters highlighted the importance of the interactions between multiple abiotic and biotic variables in shaping aphid population dynamics. Empirical research chapters three to six, using up to five lucerne genotypes (i.e. cultivars) in glasshouse and field experiments, addressed how A. pisum responded to the isolated and combined effects of climate change and root herbivory. In particular, chapter three determined the effects of elevated temperatures (eT) and elevated atmospheric CO2 concentrations (eCO2) on root-feeding S. discoideus larvae and their interaction with A. pisum. Chapter four addressed whether the effects of eT, e

  13. Plant immunity in plant–aphid interactions

    Science.gov (United States)

    Jaouannet, Maëlle; Rodriguez, Patricia A.; Lenoir, Camille J. G.; MacLeod, Ruari; Escudero-Martinez, Carmen; Bos, Jorunn I.B.

    2014-01-01

    Aphids are economically important pests that cause extensive feeding damage and transmit viruses. While some species have a broad host range and cause damage to a variety of crops, others are restricted to only closely related plant species. While probing and feeding aphids secrete saliva, containing effectors, into their hosts to manipulate host cell processes and promote infestation. Aphid effector discovery studies pointed out parallels between infection and infestation strategies of plant pathogens and aphids. Interestingly, resistance to some aphid species is known to involve plant resistance proteins with a typical NB-LRR domain structure. Whether these resistance proteins indeed recognize aphid effectors to trigger ETI remains to be elucidated. In addition, it was recently shown that unknown aphid derived elicitors can initiate reactive oxygen species (ROS) production and callose deposition and that these responses were dependent on BAK1 (BRASSINOSTERIOD INSENSITIVE 1-ASSOCIATED RECEPTOR KINASE 1) which is a key component of the plant immune system. In addition, BAK-1 contributes to non-host resistance to aphids pointing to another parallel between plant-pathogen and – aphid interactions. Understanding the role of plant immunity and non-host resistance to aphids is essential to generate durable and sustainable aphid control strategies. Although insect behavior plays a role in host selection and non-host resistance, an important observation is that aphids interact with non-host plants by probing the leaf surface, but are unable to feed or establish colonization. Therefore, we hypothesize that aphids interact with non-host plants at the molecular level, but are potentially not successful in suppressing plant defenses and/or releasing nutrients. PMID:25520727

  14. Responses of Russian Wheat Aphid (Homoptera: Aphididae) to Aphid Alarm Pheromone

    OpenAIRE

    Shah, P. A.; Pickett, J. A.; Vandenberg, J. D.

    2017-01-01

    In a series of laboratory tests, Russian wheat aphids, Diuraphis noxia (Mordvilko), responded to synthetic aphid alarm pheromone, (E)-β-farnesene, by removing stylets and leaving feeding sites or by crawling out of test arenas. Late instars and adults were more responsive than early instars. In dose-response assays, EC50 estimates ranged from 0.94 to 8.95 mg/ml among 3 experiments. In arenas, D. noxia also responded to the proximity of cornicle-damaged nymphs of either the green peach aphid, ...

  15. Genetics Coupled to Quantitative Intact Proteomics Links Heritable Aphid and Endosymbiont Protein Expression to Circulative Polerovirus Transmission▿ †

    Science.gov (United States)

    Cilia, M.; Tamborindeguy, C.; Fish, T.; Howe, K.; Thannhauser, T. W.; Gray, S.

    2011-01-01

    Yellow dwarf viruses in the family Luteoviridae, which are the causal agents of yellow dwarf disease in cereal crops, are each transmitted most efficiently by different species of aphids in a circulative manner that requires the virus to interact with a multitude of aphid proteins. Aphid proteins differentially expressed in F2 Schizaphis graminum genotypes segregating for the ability to transmit Cereal yellow dwarf virus-RPV (CYDV-RPV) were identified using two-dimensional difference gel electrophoresis (DIGE) coupled to either matrix-assisted laser desorption ionization-tandem mass spectrometry or online nanoscale liquid chromatography coupled to electrospray tandem mass spectrometry. A total of 50 protein spots, containing aphid proteins and proteins from the aphid's obligate and maternally inherited bacterial endosymbiont, Buchnera, were identified as differentially expressed between transmission-competent and refractive aphids. Surprisingly, in virus transmission-competent F2 genotypes, the isoelectric points of the Buchnera proteins did not match those in the maternal Buchnera proteome as expected, but instead they aligned with the Buchnera proteome of the transmission-competent paternal parent. Among the aphid proteins identified, many were involved in energy metabolism, membrane trafficking, lipid signaling, and the cytoskeleton. At least eight aphid proteins were expressed as heritable, isoelectric point isoform pairs, one derived from each parental lineage. In the F2 genotypes, the expression of aphid protein isoforms derived from the competent parental lineage aligned with the virus transmission phenotype with high precision. Thus, these isoforms are candidate biomarkers for CYDV-RPV transmission in S. graminum. Our combined genetic and DIGE approach also made it possible to predict where several of the proteins may be expressed in refractive aphids with different barriers to transmission. Twelve proteins were predicted to act in the hindgut of the aphid

  16. Wide dispersal of aphid-pathogenic Entomophthorales among aphids relies upon migratory alates.

    Science.gov (United States)

    Feng, Ming-Guang; Chen, Chun; Chen, Bin

    2004-05-01

    Entomophthoralean mycoses are of general importance in the natural control of aphids, but mechanisms involved in their dissemination are poorly understood. Despite several possible means of fungal survival, the dispersal of the mycoses in aphids has never been related to the flight of their migratory alates that are able to locate suitable host plants. In this study, aphid-pathogenic fungi proved to be widely disseminated among various aphids by their alates through migratory flight based on the following findings. First, up to 36.6% of the 7139 migratory alates (including nine species of vegetable or cereal aphids) trapped from air > 30 m above the ground in three provinces of China were found bearing eight species of fungal pathogens. Of those, six were aphid-specific Entomophthorales dominated in individual cases by Pandora neoaphidis, which occurs globally but has no resting spores discovered to date. Secondly, infected alates were confirmed to be able to fly for hours, to initiate colonies on plants after flight and to transmit fungal infection to their offspring in a laboratory experiment, in which 238 Sitobion avenae alates were individually flown in a computer-monitoring flight mill system after exposure to a spore shower of P. neoaphidis and then allowed to colonize host plants.

  17. AphID (Lucid key) http://AphID.AphidNet.org

    Science.gov (United States)

    This peer-reviewed web site concentrates on the 66 adult alate and apterous aphids that are the world's most cosmopolitan and polyphagous species. The site includes fact sheets about the various aphids species, a glossary of terms helpful to the student, hundreds of photographs and illustrations, a...

  18. Proteomics analysis of alfalfa response to heat stress.

    Directory of Open Access Journals (Sweden)

    Weimin Li

    Full Text Available The proteome responses to heat stress have not been well understood. In this study, alfalfa (Medicago sativa L. cv. Huaiyin seedlings were exposed to 25 °C (control and 40 °C (heat stress in growth chambers, and leaves were collected at 24, 48 and 72 h after treatment, respectively. The morphological, physiological and proteomic processes were negatively affected under heat stress. Proteins were extracted and separated by two-dimensional polyacrylamide gel electrophoresis (2-DE, and differentially expressed protein spots were identified by mass spectrometry (MS. Totally, 81 differentially expressed proteins were identified successfully by MALDI-TOF/TOF. These proteins were categorized into nine classes: including metabolism, energy, protein synthesis, protein destination/storage, transporters, intracellular traffic, cell structure, signal transduction and disease/defence. Five proteins were further analyzed for mRNA levels. The results of the proteomics analyses provide a better understanding of the molecular basis of heat-stress responses in alfalfa.

  19. Methyl salicylate, a soybean aphid-induced plant volatile attractive to the predator Coccinella septempunctata.

    Science.gov (United States)

    Zhu, Junwei; Park, Kye-Chung

    2005-08-01

    Induced volatiles provide a signal to foraging predatory insects about the location of their prey. In Iowa, early in the growing season of soybean, Glycine max, many predacious seven-spotted lady beetles, Coccinella septempunctata, were observed on plants with heavy infestations of soybean aphid, Aphis glycines. We studied whether the attraction of this beetle is caused by the release of specific volatile compounds of soybean plants infested by aphids. Volatile compounds emitted by soybean plants infested by aphids were compared with those of undamaged, uninfested, and artificially damaged plants. Gas chromatography-mass spectrometry analyses revealed consistent differences in the profiles of volatile compounds between aphid-infested soybean plants and undamaged ones. Significantly more methyl salicylate was released from infested plants at both the V1 and V2 plant growth stages. However, release patterns of two other induced plant volatiles, (D)-limonene and (E,E)-alpha-farnesene, differed between the two plant growth stages. Gas chromatographic-electroantennographic detection of volatile extracts from infested soybean plants showed that methyl salicylate elicited significant electrophysiological responses in C. septempunctata. In field tests, traps baited with methyl salicylate were highly attractive to adult C. septempunctata, whereas 2-phenylethanol was most attractive to the lacewing Chrysoperla carnea and syrphid flies. Another common lady beetle, the multicolored Asian lady beetle, Harmonia axyridis, showed no preference for the compounds. These results indicate that C. septempunctata may use methyl salicylate as the olfactory cue for prey location. We also tested the attractiveness of some selected soybean volatiles to alate soybean aphids in the field, and results showed that traps baited with benzaldehyde caught significantly higher numbers of aphids.

  20. A peptide that binds the pea aphid gut impedes entry of Pea enation mosaic virus into the aphid hemocoel

    International Nuclear Information System (INIS)

    Liu Sijun; Sivakumar, S.; Sparks, Wendy O.; Miller, W. Allen; Bonning, Bryony C.

    2010-01-01

    Development of ways to block virus transmission by aphids could lead to novel and broad-spectrum means of controlling plant viruses. Viruses in the Luteoviridae enhanced are obligately transmitted by aphids in a persistent manner that requires virion accumulation in the aphid hemocoel. To enter the hemocoel, the virion must bind and traverse the aphid gut epithelium. By screening a phage display library, we identified a 12-residue gut binding peptide (GBP3.1) that binds to the midgut and hindgut of the pea aphid Acyrthosiphon pisum. Binding was confirmed by labeling the aphid gut with a GBP3.1-green fluorescent protein fusion. GBP3.1 reduced uptake of Pea enation mosaic virus (Luteoviridae) from the pea aphid gut into the hemocoel. GBP3.1 also bound to the gut epithelia of the green peach aphid and the soybean aphid. These results suggest a novel strategy for inhibiting plant virus transmission by at least three major aphid pest species.

  1. Root-lesion nematodes suppress cabbage aphid population development by reducing aphid daily reproduction

    Directory of Open Access Journals (Sweden)

    W. H. Gera eHol

    2016-02-01

    Full Text Available Empirical studies have shown that belowground feeding herbivores can affect the performance of aboveground herbivores in different ways. Often the critical life-history parameters underlying the observed performance effects remain unexplored. In order to better understand the cause for the observed effects on aboveground herbivores, these ecological mechanisms must be better understood. In this study we combined empirical experiments with a modelling approach to analyse the effect of two root feeding endoparasitic nematodes with different feeding strategies on the population growth of the aboveground feeding specialist aphid Brevicoryne brassicae on Brassica nigra. The aim was to test whether emerging differences in life history characteristics (days until reproduction, daily reproduction would be sufficient to explain observed differences in aphid population development on plants with and without two species of nematodes. Aphid numbers were lower on plants with Pratylenchus penetrans in comparison to aphid numbers on plants with Meloidogyne spp. A dedicated experiment showed that aphid daily reproduction was lower on plants with P. penetrans (3.08 offspring per female per day in comparison to both uninfested plants and plants with Meloidogyne spp. (3.50 offspring per female per day. The species-specific reduction of aphid reproduction appeared independent of changes in amino acids, soluble sugars or the glucosinolate sinigrin in the phloem. An individual-based model revealed that relatively small differences in reproduction rate per female were sufficient to yield a similar difference in aphid populations as was found in the empirical experiments.

  2. Synergy between chemical and biological control in the IPM of currant-lettuce aphid (Nasonovia ribisnigri) in Canterbury, New Zealand.

    Science.gov (United States)

    Fagan, L L; McLachlan, A; Till, C M; Walker, M K

    2010-04-01

    Field trials were conducted at four Canterbury, New Zealand locations in 2005-06 to determine if the synergistic effects of biological control by natural enemies and standard drenching techniques controlled lettuce aphid populations throughout the entire growing season. Chemical usage significantly lowered aphid densities in the outer, wrapper and heart leaves compared to control plants at most times. However, in mid-summer, natural enemies, such as the brown lacewing (Micromus tasmaniae), 11-spotted ladybird beetle (Coccinella undecimpunctata) and small hoverfly larvae (Melanostoma fasciatum), were more than sufficient to control lettuce aphids without the use of insecticides. Drenching, in addition to natural enemy attack, appears to be required in early spring and late summer to maintain very low levels of lettuce aphid. Given the potential for imidacloprid resistance to develop, it may be advisable to restrict drenches to these key periods in order to allow populations of natural enemies to maintain control of prey populations. We recommend industry support the validation of action thresholds across different regions within New Zealand and focus on the seasonal biology of predators to assist growers with the sustainable long-term control of lettuce aphids. The inclusion of additional data into an economic model to compare pest damage with predator loading would be useful for growers in managing aphid problems. These results will assist in the continued improvement and development of a sustainable IPM strategy for lettuce aphids in New Zealand and elsewhere.

  3. Plant-aphid interactions: molecular and ecological perspectives.

    Science.gov (United States)

    Goggin, Fiona L

    2007-08-01

    Many aphids are major agricultural pests because of their unparalleled reproductive capacity and their ability to manipulate host plant physiology. Aphid population growth and its impact on plant fitness are strongly influenced by interactions with other organisms, including plant pathogens, endophytes, aphid endosymbionts, predators, parasitoids, ants, and other herbivores. Numerous molecular and genomic resources have recently been developed to identify sources of aphid resistance in plants, as well as potentially novel targets for control in aphids. Moreover, the same model systems that are used to explore direct molecular interactions between plants and aphids can be utilized to study the ecological context in which they occur.

  4. Escherichia coli K-12 pathogenicity in the pea aphid, Acyrthosiphon pisum, reveals reduced antibacterial defense in aphids.

    Science.gov (United States)

    Altincicek, Boran; Ter Braak, Bas; Laughton, Alice M; Udekwu, Klas I; Gerardo, Nicole M

    2011-10-01

    To better understand the molecular basis underlying aphid immune tolerance to beneficial bacteria and immune defense to pathogenic bacteria, we characterized how the pea aphid Acyrthosiphon pisum responds to Escherichia coli K-12 infections. E. coli bacteria, usually cleared in the hemolymph of other insect species, were capable of growing exponentially and killing aphids within a few days. Red fluorescence protein expressing E. coli K-12 laboratory strain multiplied in the aphid hemolymph as well as in the digestive tract, resulting in death of infected aphids. Selected gene deletion mutants of the E. coli K-12 predicted to have reduced virulence during systemic infections showed no difference in either replication or killing rate when compared to the wild type E. coli strain. Of note, however, the XL1-Blue E. coli K-12 strain exhibited a significant lag phase before multiplying and killing aphids. This bacterial strain has recently been shown to be more sensitive to oxidative stress than other E. coli K-12 strains, revealing a potential role for reactive oxygen species-mediated defenses in the otherwise reduced aphid immune system. Copyright © 2011 Elsevier Ltd. All rights reserved.

  5. Aphid egg protection by ants: a novel aspect of the mutualism between the tree-feeding aphid Stomaphis hirukawai and its attendant ant Lasius productus

    Science.gov (United States)

    Matsuura, Kenji; Yashiro, Toshihisa

    2006-10-01

    Aphids often form mutualistic associations with ants, in which the aphids provide the ants with honeydew and the ants defend the aphids from predators. In this paper, we report aphid egg protection by ants as a novel aspect of the deeply interdependent relationship between a tree-feeding aphid and its attendant ant. The ant Lasius productus harbours oviparous females, males, and eggs of the hinoki cypress-feeding aphid Stomaphis hirukawai in its nests in winter. We investigated the behaviour of ants kept with aphid eggs in petri dishes to examine whether the ants recognise the aphid eggs and tend them or only provide a refuge for the aphids. Workers carried almost all of the aphid eggs into the nest within 24 h. The ants indiscriminately tended aphid eggs collected from their own colonies and those from other ant colonies. The ants cleaned the eggs and piled them up in the nest, and egg tending by ants dramatically increased aphid egg survival rates. Starving the ants showed no significant effect on aphid egg survivorship. Without ants, aphid eggs were rapidly killed by fungi. These results suggested that grooming by the ants protected the aphid eggs, at least, against pathogenic fungi. This hygienic service afforded by the ants seems indispensable for egg survival of these aphids in an environment rich in potentially pathogenic microorganisms.

  6. Partial aphid resistance in lettuce negatively affects parasitoids.

    Science.gov (United States)

    Lanteigne, Marie-Eve; Brodeur, Jacques; Jenni, Sylvie; Boivin, Guy

    2014-10-01

    This study investigated the effects of partial plant resistance on the lettuce aphid Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae), a major pest of cultivated lettuce (Lactuca sativa L.), and one of its parasitoids, Aphidius ervi Haliday (Hymenoptera: Braconidae). Aphids were reared on susceptible (L. sativa variety Estival; S) or partially resistant (Lactuca serriola L. PI 491093; PR) lettuce, and next parasitized by A. ervi females. Fitness proxies were measured for both aphids and parasitoids. Developmental time to adult stage took longer for alate and apterous aphids (an average of 3.5 and 1.5 additional days, respectively) on PR than on S lettuce, and fecundity of alate aphids reared on PR lettuce was reduced by 37.8% relative to those reared on S lettuce. Size (tibia length) and weight of aphids reared on PR lettuce were lower than for aphids reared on S lettuce from the third and second instar onward, respectively. Parasitism of aphids reared on PR plants resulted in lower parasitoid offspring emergence (-49.9%), lower adult female (-30.3%) and male (-27.5%) weight, smaller adult female (-17.5%) and male (-11.9%) size, and lower female fecundity (37.8% fewer eggs) than when parasitoids developed from aphids reared on S plants. Our results demonstrate that partial aphid resistance in lettuce negatively affects both the second and third trophic levels. Host plant resistance in cultivated lettuce may therefore create an ecological sink for aphid parasitoids.

  7. Chlorotic feeding injury by the black pecan aphid (hemiptera: aphididae) to pecan foliage promotes aphid settling and nymphal development.

    Science.gov (United States)

    Cottrell, Ted E; Wood, Bruce W; Ni, Xinzhi

    2009-04-01

    The nature of the interaction between the black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), and the chlorosis it causes to foliage of its pecan [Carya illinoinensis (Wangenh.) K. Koch)] host is poorly understood. Laboratory experiments were conducted on the settling behavior of the black pecan aphid, when provided chlorotic pecan leaf discs resulting from previous black pecan aphid feeding and nonchlorotic leaf discs, under a normal photoperiod and constant dark. Additionally, aphid development from the first instar to the adult stage was examined when nymphs were either allowed to feed on the same leaf disc or moved daily to a new, nondamaged, same age leaf disc. After 24 h, a significantly higher percentage of black pecan aphids settled on chlorotic than on nonchlorotic leaf discs, regardless of photoperiod. When starting from the first instar, nymphs that were prevented from inducing leaf chlorosis by moving daily to new, same-age leaf discs took approximately 5 d longer to complete development, had a shorter body length, and had higher mortality than when aphids remained on the same leaf disc. These results show that black pecan aphid-induced leaf chlorosis plays an important role in the interaction of the black pecan aphid with its pecan host.

  8. For the Aphid fauna in the territory of Yenisei river basin. Communication 1. Aphids on coniferous plants

    Directory of Open Access Journals (Sweden)

    A. V. Gurov

    2016-02-01

    Full Text Available The paper reports on new and previously not well-known data on insufficiently studied fauna of aphids living on coniferous trees in Central Siberia of the basin of Yenisei river. This region is the extensive transect of latitudinal geographic zones from semi-desert in the South to the arctic deserts in the North. That is why this region is very peculiar. This is the reason for insufficient study of regional entomological fauna. Aphids (Homoptera: Aphidoideaare a very taxonomically and ecologically heterogeneous group of insects. The aphids living on conifer trees are notstudied completely on the territory of Yenisei basin. Due to this, the studying of not well-known and economicallyimportant aphids is actual. For example, the insufficient study of regional aphids is confirmed by the fact, that duringthree weeks only of the work for INTAS-94-0930 Project two new aphid species were found and described on thisterritory. Also, the new species of family Mindaridae, which was described in Mongolia in 1980, was found in Siberiafor the first time. These finds indicate the real possibility to describe an interesting conifer aphid complex in the absolutely unstudied forested territory between Angara and Lower Tunguska rivers. Geographical location, dates ofcollection and feeding preferences of different species are described. A general review of Yenisei basin Siberian aphidfauna is suggested for the first time ever.

  9. Aphid reproductive investment in response to mortality risks

    Science.gov (United States)

    2010-01-01

    Background Aphids are striking in their prodigious reproductive capacity and reliance on microbial endosymbionts, which provision their hosts with necessary amino acids and provide protection against parasites and heat stress. Perhaps as a result of this bacterial dependence, aphids have limited immune function that may leave them vulnerable to bacterial pathogens. An alternative, non-immunological response that may be available to infected aphids is to increase reproduction, thereby ameliorating fitness loss from infection. Such a response would reduce the need to mount a potentially energetically costly immune response, and would parallel that of other hosts that alter life-history traits when there is a risk of infection. Here we examined whether pea aphids (Acyrthosiphon pisum) respond to immunological challenges by increasing reproduction. As a comparison to the response to the internal cue of risk elicited by immunological challenge, we also exposed pea aphids to an external cue of risk - the aphid alarm pheromone (E)-β-farnesene (EBF), which is released in the presence of predators. For each challenge, we also examined whether the presence of symbionts modified the host response, as maintaining host fitness in the face of challenge would benefit both the host and its dependent bacteria. Results We found that aphids stabbed abdominally with a sterile needle had reduced fecundity relative to control aphids but that aphids stabbed with a needle bearing heat-killed bacteria had reproduction intermediate, and statistically indistinguishable, to the aphids stabbed with a sterile needle and the controls. Aphids with different species of facultative symbiotic bacteria had different reproductive patterns overall, but symbionts in general did not alter aphid reproduction in response to bacterial exposure. However, in response to exposure to alarm pheromone, aphids with Hamiltonella defensa or Serratia symbiotica symbiotic infections increased reproduction but those

  10. Facultative symbiont infections affect aphid reproduction.

    Directory of Open Access Journals (Sweden)

    Jean-Christophe Simon

    Full Text Available Some bacterial symbionts alter their hosts reproduction through various mechanisms that enhance their transmission in the host population. In addition to its obligatory symbiont Buchnera aphidicola, the pea aphid Acyrthosiphon pisum harbors several facultative symbionts influencing several aspects of host ecology. Aphids reproduce by cyclical parthenogenesis whereby clonal and sexual reproduction alternate within the annual life cycle. Many species, including the pea aphid, also show variation in their reproductive mode at the population level, with some lineages reproducing by cyclical parthenogenesis and others by permanent parthenogenesis. While the role of facultative symbionts has been well studied during the parthenogenetic phase of their aphid hosts, very little is known on their possible influence during the sexual phase. Here we investigated whether facultative symbionts modulate the capacity to produce sexual forms in various genetic backgrounds of the pea aphid with controlled symbiont composition and also in different aphid genotypes from natural populations with previously characterized infection status and reproductive mode. We found that most facultative symbionts exhibited detrimental effects on their hosts fitness under sex-inducing conditions in comparison with the reference lines. We also showed that the loss of sexual phase in permanently parthenogenetic lineages of A. pisum was not explained by facultative symbionts. Finally, we demonstrated that Spiroplasma infection annihilated the production of males in the host progeny by inducing a male-killing phenotype, an unexpected result for organisms such as aphids that reproduce primarily through clonal reproduction.

  11. Facultative symbiont infections affect aphid reproduction.

    Science.gov (United States)

    Simon, Jean-Christophe; Boutin, Sébastien; Tsuchida, Tsutomu; Koga, Ryuichi; Le Gallic, Jean-François; Frantz, Adrien; Outreman, Yannick; Fukatsu, Takema

    2011-01-01

    Some bacterial symbionts alter their hosts reproduction through various mechanisms that enhance their transmission in the host population. In addition to its obligatory symbiont Buchnera aphidicola, the pea aphid Acyrthosiphon pisum harbors several facultative symbionts influencing several aspects of host ecology. Aphids reproduce by cyclical parthenogenesis whereby clonal and sexual reproduction alternate within the annual life cycle. Many species, including the pea aphid, also show variation in their reproductive mode at the population level, with some lineages reproducing by cyclical parthenogenesis and others by permanent parthenogenesis. While the role of facultative symbionts has been well studied during the parthenogenetic phase of their aphid hosts, very little is known on their possible influence during the sexual phase. Here we investigated whether facultative symbionts modulate the capacity to produce sexual forms in various genetic backgrounds of the pea aphid with controlled symbiont composition and also in different aphid genotypes from natural populations with previously characterized infection status and reproductive mode. We found that most facultative symbionts exhibited detrimental effects on their hosts fitness under sex-inducing conditions in comparison with the reference lines. We also showed that the loss of sexual phase in permanently parthenogenetic lineages of A. pisum was not explained by facultative symbionts. Finally, we demonstrated that Spiroplasma infection annihilated the production of males in the host progeny by inducing a male-killing phenotype, an unexpected result for organisms such as aphids that reproduce primarily through clonal reproduction.

  12. Do aphid colonies amplify their emission of alarm pheromone?

    Science.gov (United States)

    Hatano, Eduardo; Kunert, Grit; Bartram, Stefan; Boland, Wilhelm; Gershenzon, Jonathan; Weisser, Wolfgang W

    2008-09-01

    When aphids are attacked by natural enemies, they emit alarm pheromone to alert conspecifics. For most aphids tested, (E)-beta-farnesene (EBF) is the main, or only, constituent of the alarm pheromone. In response to alarm pheromone, alerted aphids drop off the plant, walk away, or attempt to elude predators. However, under natural conditions, EBF concentration might be low due to the low amounts emitted, to rapid air movement, or to oxidative degradation. To ensure that conspecifics are warned, aphids might conceivably amplify the alarm signal by emitting EBF in response to EBF emitted by other aphids. To examine whether such amplification occurs, we synthesized deuterated EBF (DEBF), which allowed us to differentiate between applied and aphid-derived chemical. Colonies of Acyrthosiphon pisum were treated with DEBF, and headspace volatiles were collected and analyzed for evidence of aphid-derived EBF. No aphid-derived EBF was detected, suggesting that amplification of the alarm signal does not occur. We discuss the disadvantages of alarm signal reinforcement.

  13. The Potato Aphid Salivary Effector Me47 Is a Glutathione-S-Transferase Involved in Modifying Plant Responses to Aphid Infestation.

    Science.gov (United States)

    Kettles, Graeme J; Kaloshian, Isgouhi

    2016-01-01

    Polyphagous aphid pests cause considerable economic damage to crop plants, primarily through the depletion of photoassimilates and transfer of viruses. The potato aphid (Macrosiphum euphorbiae) is a notable pest of solanaceous crops, however, the molecular mechanisms that underpin the ability to colonize these hosts are unknown. It has recently been demonstrated that like other aphid species, M. euphorbiae injects a battery of salivary proteins into host plants during feeding. It is speculated that these proteins function in a manner analagous to secreted effectors from phytopathogenic bacteria, fungi and oomycetes. Here, we describe a novel aphid effector (Me47) which was identified from the potato aphid salivary secretome as a putative glutathione-S-transferase (GST). Expression of Me47 in Nicotiana benthamiana enhanced reproductive performance of green peach aphid (Myzus persicae). Similarly, delivery of Me47 into leaves of tomato (Solanum lycopersicum) by Pseudomonas spp. enhanced potato aphid fecundity. In contrast, delivery of Me47 into Arabidopsis thaliana reduced GPA reproductive performance, indicating that Me47 impacts the outcome of plant-aphid interactions differently depending on the host species. Delivery of Me47 by the non-pathogenic Pseudomonas fluorescens revealed that Me47 protein or activity triggers defense gene transcriptional upregulation in tomato but not Arabidopsis. Recombinant Me47 was purified and demonstrated to have GST activity against two specific isothiocyanates (ITCs), compounds implicated in herbivore defense. Whilst GSTs have previously been associated with development of aphid resistance to synthetic insecticides, the findings described here highlight a novel function as both an elicitor and suppressor of plant defense when delivered into host tissues.

  14. Ants farm subterranean aphids mostly in single clone groups

    DEFF Research Database (Denmark)

    Ivens, Aniek B.F.; Kronauer, Daniel Jan Christoph; Pen, Ido

    2012-01-01

    mutualisms have been studied in sufficient genetic detail to address these issues, so we decided to characterize symbiont diversity in the complex mutualism between multiple root aphid species and Lasius flavus ants. After showing elsewhere that three of these aphid species have low dispersal and mostly...... if not exclusively asexual reproduction, we here investigate aphid diversity within and between ant nest mounds. Results The three focal species (Geoica utricularia, Forda marginata and Tetraneura ulmi) had considerable clonal diversity at the population level. Yet more than half of the ant mounds contained just....... The ants appear to eat most of the early instar aphids, so that adult aphids are unlikely to face limited phloem resources and scramble competition with other aphids. We suggest that such culling of carbohydrate-providing symbionts for protein ingestion may maintain maximal host yield per aphid while also...

  15. Efecto de las arañas (Arachnida: Araneae como depredadoras de insectos plaga en cultivos de alfalfa (Medicago sativa (Fabaceae en Argentina

    Directory of Open Access Journals (Sweden)

    Andrea Armendano

    2011-12-01

    Full Text Available Effect of spiders (Arachnida: Araneae as predators of insect pest in alfalfa crops (Medicago sativa (Fabaceae in Argentina. Spiders are predators that reduce insect pest populations in agroecosystems. Trials were conducted to measure the selectivity against different insect preys, the daily consumption, effect of predators alone and together with a known number of preys, and the indirect effect of predators on vegetation. For this, experimental units (1x1m were used covered with a fine plastic mesh. Misumenops pallidus, Oxyopes salticus and Araneus sp. were used as generalist predators, and aphids, weevils, locusts, chrysomelids and Lepidoptera larvae as their potential preys. Among the preys offered, the spiders preferred Lepidoptera larvae compared to the other two pests groups (weevils and aphids. The maximum consumption rate was of 93.33% for Lepidoptera larvae, 25.33% for aphids and 11.67% for weevils. The Q Index values for the three species of spiders showed a positive selectivity only for defoliating larvae. O. salticus showed the highest values of consumption rates while Rachiplusia nu was the most consumed. The maximum value of consumption in 24 hours was showed by O. salticus on R. nu (C=2.8. The association of several species of predatory spiders increased the total number of insects captured, and also showed that the addition of spiders caused a decrease in the number of leaves damaged by the effect of lepidopterous larvae. Rev. Biol. Trop. 59 (4: 1651-1662. Epub 2011 December 01

  16. The potato aphid salivary effector Me47 is a glutathione-S-transferase involved in modifying plant responses to aphid infestation

    Directory of Open Access Journals (Sweden)

    Graeme James Kettles

    2016-08-01

    Full Text Available Polyphagous aphid pests cause considerable economic damage to crop plants, primarily through the depletion of photoassimilates and transfer of viruses. The potato aphid (Macrosiphum euphorbiae is a notable pest of solanaceous crops, however the molecular mechanisms that underpin the ability to colonize these hosts are unknown. It has recently been demonstrated that like other aphid species, M. euphorbiae injects a battery of salivary proteins into host plants during feeding. It is speculated that these proteins function in a manner analagous to secreted effectors from phytopathogenic bacteria, fungi and oomycetes. Here we describe a novel aphid effector (Me47 which was identified from the potato aphid salivary secretome as a putative glutathione-S-transferase (GST. Expression of Me47 in Nicotiana benthamiana enhanced reproductive performance of green peach aphid (Myzus persicae. Similarly, delivery of Me47 into leaves of tomato (Solanum lycopersicum by Pseudomonas spp. enhanced potato aphid fecundity. In contrast, delivery of Me47 into Arabidopsis thaliana reduced GPA reproductive performance, indicating that Me47 impacts the outcome of plant-aphid interactions differently depending on the host species. Delivery of Me47 by the non-pathogenic Pseudomonas fluorescens revealed that Me47 protein or activity triggers defense gene transcriptional upregulation in tomato but not Arabidopsis. Recombinant Me47 was purified and demonstrated to have GST activity against two specific isothiocyanates (ITCs, compounds implicated in herbivore defense. Whilst GSTs have previously been associated with development of aphid resistance to synthetic insecticides, the findings described here highlight a novel function as both an elicitor and suppressor of plant defense when delivered into host tissues.

  17. Improvement of wheat for resistance to Russian Wheat Aphid

    International Nuclear Information System (INIS)

    Kinyua, M.; Malinga, J.N.; Wanyama, J.; Karanja, L.; Njau, P.; Leo, T.; Alomba, E.

    2001-01-01

    Breeding for resistance against Russian wheat aphid in Kenya is reported. Results of six of the lines were found to have high to moderate resistance to Russian wheat aphid. Popular lines were susceptible in the greenhouse when subjected to aphid pressure but showed moderate susceptibility when screened under field conditions, indicating that in years or location with low aphid pressure farmers may still get a crop. However in areas of high aphid pressure or bad years they may lose their crop. Consequently, developing resistant/torerant varieties is urgent

  18. Spruce aphid (Elatobium abietinum Walker) (Hemiptera: Aphididae) [Chapter XXIV

    Science.gov (United States)

    Ann M. Lynch

    2014-01-01

    Elatobium abietinum Walker is a spruce-feeding aphid that in Europe is referred to as the green spruce aphid (Day et al., 1998a) (Fig. 1). However, in North America E. abietinum is known simply as the spruce aphid, while the common name "green spruce aphid" refers to a different species, Cinara fornacula Hottes (Hemiptera: Aphididae) (http://www.entsoc.org/...

  19. The Nerium oleander aphid Aphis nerii is tolerant to a local isolate of Aphid lethal paralysis virus (ALPV).

    Science.gov (United States)

    Dombrovsky, Aviv; Luria, Neta

    2013-04-01

    In a survey that was conducted during the year 2011, a local strain of Aphid lethal paralysis virus (ALPV) was identified and isolated from a wild population of Aphis nerii aphids living on Nerium oleander plants located in northern Israel. The new strain was tentatively named (ALPV-An). RNA extracted from the viral particles allowed the amplification and determination of the complete genome sequence. The virus genome is comprised of 9835 nucleotides. In a BLAST search analysis, the ALPV-An sequence showed 89 % nucleotide sequence identity with the whole genome of a South African ALPV and 96 and 94 % amino acid sequence identity with the ORF1 and ORF2 of that strain, respectively. In preliminary experiments, spray-applied, purified ALPV virions were highly pathogenic to the green peach aphid Myzus persicae; 95 % mortality was recorded 4 days post-infection. These preliminary results demonstrate the potential of ALPV for use as a biologic agent for some aphid control. Surprisingly, no visible ALPV pathogenic effects, such as morphological changes or paralysis, were observed in the A. nerii aphids infected with ALPV-An. The absence of clear ALPV symptoms in A. nerii led to the formulation of two hypotheses, which were partially examined in this study. The first hypothesis suggest that A. nerii is resistant or tolerant of ALPV, while the second hypothesis propose that ALPV-An may be a mild strain of ALPV. Currently, our results is in favor with the first hypothesis since ALPV-An is cryptic in A. nerii aphids and can be lethal for M. persicae aphids.

  20. Betaines of Alfalfa 1

    Science.gov (United States)

    Wood, Karl V.; Stringham, Kelly J.; Smith, David L.; Volenec, Jeffrey J.; Hendershot, Kerry L.; Jackson, Kimberly A.; Rich, Patrick J.; Yang, Wen-Ju; Rhodes, David

    1991-01-01

    Leaf tissue of alfalfa (Medicago sativa L.) was found to contain prolinebetaine, pipecolatebetaine, hydroxyprolinebetaine, and glycinebetaine. As n-butyl esters, these chemical species exhibit molecular cations at mass/charge ratio (m/z) 200, 214, 216, and 174, respectively, when analyzed by fast atom bombardment mass spectrometry. The underivatized betaines exhibit protonated molecular ions at m/z 144, 158, 160, and 118, respectively, when analyzed by desorption chemical ionization mass spectrometry. Extensive (>45-fold) genotypic variation for hydroxyprolinebetaine level was identified in alfalfa. Because a significant inverse correlation between prolinebetaine and hydroxyprolinebetaine levels was observed among 15 alfalfa genotypes evaluated, it is possible that these compounds may be derived from a common intermediate. Birdsfoot trefoil (Lotus corniculatus L.) contained prolinebetaine, but only traces of glycinebetaine, pipecolatebetaine, and hydroxyprolinebetaine. Red clover (Trifolium pratense L.) lacked prolinebetaine, pipecolatebetaine, and hydroxyprolinebetaine, but contained appreciable levels of both glycinebetaine and trigonelline. Trigonelline was not detectable in the leaf tissue of any alfalfa genotype or cultivar evaluated. PMID:16668271

  1. Reduced Lignin Alfalfa - Update

    Science.gov (United States)

    U.S. farmers harvested alfalfa (Medicago sativa) for hay or haylage from 24.5million acres in 2009. Midwestern states harvested 57 % of 2009 acreage for hay and haylage. However, acreage is stable to declining. Alfalfa provides an excellent source of fiber, protein, minerals and vitamins that partia...

  2. New genus and species of the extinct aphid family Szelegiewicziidae and their implications for aphid evolution

    DEFF Research Database (Denmark)

    Wegierek, Piotr; Zyła, Dagmara Maria; Homan, Agnieszka

    2017-01-01

    of the extinct groups. The extinct aphid family Szelegiewicziidae is supposed to be one of the oviparous lineages in aphid evolution. New material from the rock fossil deposits of Shar Teg (Upper Jurassic of Mongolia), Baissa (Lower Cretaceous of Siberia-Russia), and Burmese amber (Upper Cretaceous of Myanmar...

  3. [Soil dryness characteristics of alfalfa cropland and optimal growth years of alfalfa on the Loess Plateau of central Gansu, China].

    Science.gov (United States)

    Luo, Zhu-zhu; Li, Ling-ling; Niu, Yi-ning; Cai, Li-qun; Zhang, Ren-zhi; Xie, Jun-hong

    2015-10-01

    This paper investigated soil moisture in alfalfa (Medicago sativa) cropland with different growth years (1, 3, 8, 12 and 14 years) and discussed the optimum growth years of alfalfa on the Loess Plateau of central Gansu. The results showed that the soil moisture along 0-300 cm soil profile of alfalfa croplands with different growth years was obviously lower than that of the local soil stable moisture. The soil water contents in croplands with alfalfa that had grown for 12 and 14 years were only 9.2% and 7.1% of local soil stable moisture, respectively, which were even lower than the lower limit of alfalfa growth. The average soil dryness indexes along 0-300 cm soil profile in 1, 3, 8, 12 and 14 years alfalfa croplands were 125.4%, 30.5%, 18.4%, -34.2% and -83.3% respectively. The results indicated that soil dryness occurred to varying degrees with different growth years except croplands with alfalfa grown for 1 year. With the increase of growth years of alfalfa, the soil dryness intensity increased and the soil dryness rate decreased. According to the soil moisture and alfalfa productivity results in this study, it could be concluded that the optimum growth years of alfalfa are 8-10 years in semiarid areas of the Loess Plateau.

  4. Alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Fu, Chunxiang; Hernandez, Timothy; Zhou, Chuanen; Wang, Zeng-Yu

    2015-01-01

    Alfalfa (Medicago sativa L.) is a high-quality forage crop widely grown throughout the world. This chapter describes an efficient protocol that allows for the generation of large number of transgenic alfalfa plants by sonication-assisted Agrobacterium-mediated transformation. Binary vectors carrying different selectable marker genes that confer resistance to phosphinothricin (bar), kanamycin (npt II), or hygromycin (hph) were used to generate transgenic alfalfa plants. Intact trifoliates collected from clonally propagated plants in the greenhouse were sterilized with bleach and then inoculated with Agrobacterium strain EHA105. More than 80 % of infected leaf pieces could produce rooted transgenic plants in 4-5 months after Agrobacterium-mediated transformation.

  5. Investigating the origin of the Chinese name for alfalfa

    Science.gov (United States)

    Sun, Q. Z.; Xu, L. J.; Tang, X. J.; Ma, J. T.; Wang, D.; Li, D.; Liu, Q.; Tao, Y.; Li, F.

    2017-02-01

    It is assured that alfalfa (Medicago sativa L.) was introduced in Han dynasty. There are cognitive differences on whether Zhang Qian introduced alfalfa. Based on the previous studies, research inductive method was used. The relationship between Zhang Qian and alfalfa introduction was analyzed from the motivation, experience and influence of Zhang Qian to the Western Regions and the image generation of Zhang Qian brought back alfalfa’s seeds. Till to now, there are four opinions about Zhang Qian introducing Alfalfa seeds, including : (1) Zhang Qian introduced alfalfa seeds;(2) Zhang Qian did not introduce alfalfa seeds;(3) the information of Zhang Qian transferring alfalfa;(4)for commemoration Zhang Qian to the Western Regions. Although there are not direct historical materials to support Zhang Qian brought alfalfa seed to Han dynasty, it believes and confirms that the introducing of alfalfa is inextricably interwoven with Zhang Qian’s western travel. Zhangqian brought relative information from western regions during the introduction, which was the basis of non-native theory, and after that, Chinese began to plant alfalfa in Han dynasty., According to historical literatures, it is clear that the Chinese diplomat brought alfalfa seeds back to China. Alfalfa, as the favorite forage to Ferghana horse, have been already planted in Dawan in Han dynasty. Despite the debate, Zhangqian played an important pioneering role in introducing alfalfa.

  6. Role of the aphid species and their feeding locations in parasitization behavior of Aphelinus abdominalis, a parasitoid of the lettuce aphid Nasonovia ribisnigri

    Science.gov (United States)

    Shrestha, Govinda; Skovgård, Henrik; Reddy, Gadi V. P.; Steenberg, Tove; Enkegaard, Annie

    2017-01-01

    Aphid species feeding on lettuce occupy distinct feeding sites: the lettuce aphid Nasonovia ribisnigri prefers to feed on heart leaves, whereas the potato aphid Macrosiphum euphorbiae feeds only on outer leaves. The aphid parasitoid Aphelinus abdominalis, known to be able to regulate M. euphorbiae on many crops, has recently been indicated as a promising biocontrol candidate also for use against N. ribisnigri, a major pest of lettuce. This study therefore examined A. abdominalis parasitization preference between N. ribisnigri and M. euphorbiae and its ability to parasitize aphids feeding on different parts of lettuce plants. In addition, life history traits of A. abdominalis on these aphid species were investigated. In no-choice laboratory experiments on leaf discs and 24 h exposure, A. abdominalis successfully parasitized 54% and 60% of the offered N. ribisnigri and M. euphorbiae, respectively, with no significant difference. In the corresponding choice experiment, however, A. abdominalis had a tendency for a significantly higher preference for M. euphorbiae (38%) compared to N. ribisnigri (30%). Growth chamber experiments on whole plants demonstrated that A. abdominalis was able to parasitize aphids, regardless of their feeding locations on lettuce plants. However, aphid feeding behavior had a significant effect on the parasitization rate. A. abdominalis parasitized significantly higher percentages of M. euphorbiae or N. ribisnigri when aphids were exposed separately to parasitoids on whole lettuce plants as compared with N. ribisnigri exposed only on heart leaf. A significant preference of A. abdominalis for M. euphorbiae compared to N. ribisnigri was also observed in the growth chamber choice experiment. A high percentage of adult emergence (> 84%) and female-biased sex ratio (> 83%) were found irrespective of the aphid species. PMID:28854232

  7. Role of the aphid species and their feeding locations in parasitization behavior of Aphelinus abdominalis, a parasitoid of the lettuce aphid Nasonovia ribisnigri.

    Science.gov (United States)

    Shrestha, Govinda; Skovgård, Henrik; Reddy, Gadi V P; Steenberg, Tove; Enkegaard, Annie

    2017-01-01

    Aphid species feeding on lettuce occupy distinct feeding sites: the lettuce aphid Nasonovia ribisnigri prefers to feed on heart leaves, whereas the potato aphid Macrosiphum euphorbiae feeds only on outer leaves. The aphid parasitoid Aphelinus abdominalis, known to be able to regulate M. euphorbiae on many crops, has recently been indicated as a promising biocontrol candidate also for use against N. ribisnigri, a major pest of lettuce. This study therefore examined A. abdominalis parasitization preference between N. ribisnigri and M. euphorbiae and its ability to parasitize aphids feeding on different parts of lettuce plants. In addition, life history traits of A. abdominalis on these aphid species were investigated. In no-choice laboratory experiments on leaf discs and 24 h exposure, A. abdominalis successfully parasitized 54% and 60% of the offered N. ribisnigri and M. euphorbiae, respectively, with no significant difference. In the corresponding choice experiment, however, A. abdominalis had a tendency for a significantly higher preference for M. euphorbiae (38%) compared to N. ribisnigri (30%). Growth chamber experiments on whole plants demonstrated that A. abdominalis was able to parasitize aphids, regardless of their feeding locations on lettuce plants. However, aphid feeding behavior had a significant effect on the parasitization rate. A. abdominalis parasitized significantly higher percentages of M. euphorbiae or N. ribisnigri when aphids were exposed separately to parasitoids on whole lettuce plants as compared with N. ribisnigri exposed only on heart leaf. A significant preference of A. abdominalis for M. euphorbiae compared to N. ribisnigri was also observed in the growth chamber choice experiment. A high percentage of adult emergence (> 84%) and female-biased sex ratio (> 83%) were found irrespective of the aphid species.

  8. Role of the aphid species and their feeding locations in parasitization behavior of Aphelinus abdominalis, a parasitoid of the lettuce aphid Nasonovia ribisnigri.

    Directory of Open Access Journals (Sweden)

    Govinda Shrestha

    Full Text Available Aphid species feeding on lettuce occupy distinct feeding sites: the lettuce aphid Nasonovia ribisnigri prefers to feed on heart leaves, whereas the potato aphid Macrosiphum euphorbiae feeds only on outer leaves. The aphid parasitoid Aphelinus abdominalis, known to be able to regulate M. euphorbiae on many crops, has recently been indicated as a promising biocontrol candidate also for use against N. ribisnigri, a major pest of lettuce. This study therefore examined A. abdominalis parasitization preference between N. ribisnigri and M. euphorbiae and its ability to parasitize aphids feeding on different parts of lettuce plants. In addition, life history traits of A. abdominalis on these aphid species were investigated. In no-choice laboratory experiments on leaf discs and 24 h exposure, A. abdominalis successfully parasitized 54% and 60% of the offered N. ribisnigri and M. euphorbiae, respectively, with no significant difference. In the corresponding choice experiment, however, A. abdominalis had a tendency for a significantly higher preference for M. euphorbiae (38% compared to N. ribisnigri (30%. Growth chamber experiments on whole plants demonstrated that A. abdominalis was able to parasitize aphids, regardless of their feeding locations on lettuce plants. However, aphid feeding behavior had a significant effect on the parasitization rate. A. abdominalis parasitized significantly higher percentages of M. euphorbiae or N. ribisnigri when aphids were exposed separately to parasitoids on whole lettuce plants as compared with N. ribisnigri exposed only on heart leaf. A significant preference of A. abdominalis for M. euphorbiae compared to N. ribisnigri was also observed in the growth chamber choice experiment. A high percentage of adult emergence (> 84% and female-biased sex ratio (> 83% were found irrespective of the aphid species.

  9. Water transfer in an alfalfa/maize association

    International Nuclear Information System (INIS)

    Corak, S.J.; Blevins, D.G.; Pallardy, S.G.

    1987-01-01

    The authors investigated the possibility of interspecific water transfer in an alfalfa (Medicago sativa L.) and maize (Zea mays L.) association. An alfalfa plant was grown through two vertically stacked plastic tubes. A 5 centimeter air gap between tubes was bridged by alfalfa roots. Five-week old maize plants with roots confined to the top tube were not watered, while associated alfalfa roots had free access to water in the bottom tube (the -/+ treatment). Additional treatments included: top and bottom tubes watered (+/+), top and bottom tubes droughted (-/-), and top tube droughted after removal of alfalfa root bridges and routine removal of alfalfa tillers (-*). Predawn leaf water potential of maize in the -/+ treatment fell to -1.5 megapascals 13 days after the start of drought; thereafter, predawn and midday potentials were maintained near -1.9 megapascals. Leaf water potentials of maize in the -/- and -* treatments declined steadily; all plants in these treatments were completely desiccated before day 50. High levels of tritium activity were detected in water extracted from both alfalfa and maize leaves after 3 H 2 O was injected into the bottom -/+ tube at day 70 or later. Maize in the -/+ treatment was able to survive an otherwise lethal period of drought by utilizing water lost by alfalfa roots

  10. Role of the aphid species and their feeding locations in parasitization behavior of Aphelinus abdominalis, a parasitoid of the lettuce aphid Nasonovia ribisnigri

    OpenAIRE

    Shrestha, Govinda; Skovg?rd, Henrik; Reddy, Gadi V. P.; Steenberg, Tove; Enkegaard, Annie

    2017-01-01

    Aphid species feeding on lettuce occupy distinct feeding sites: the lettuce aphid Nasonovia ribisnigri prefers to feed on heart leaves, whereas the potato aphid Macrosiphum euphorbiae feeds only on outer leaves. The aphid parasitoid Aphelinus abdominalis, known to be able to regulate M. euphorbiae on many crops, has recently been indicated as a promising biocontrol candidate also for use against N. ribisnigri, a major pest of lettuce. This study therefore examined A. abdominalis parasitizatio...

  11. Seasonal Abundance of Aphids and Aphidophagous Insects in Pecan

    Directory of Open Access Journals (Sweden)

    Ghulam Abbas

    2012-12-01

    Full Text Available Seasonal occurrence of aphids and aphidophagous insects was monitored for six years (2006–2011 from full leaf expansion in May to leaf fall in October in “Desirable” variety pecan trees that were not treated with insecticides. Aphid outbreaks occurred two times per season, once in the spring and again in the late summer. Yellow pecan and blackmargined aphids exceeded the recommended treatment thresholds one time and black pecan aphids exceeded the recommended treatment levels three times over the six seasons. Increases in aphidophagous insect abundance coincided with aphid outbreaks in five of the six seasons. Among aphidophagous insects Harmonia axyridis and Olla v-nigrum were frequently collected in both the tree canopy and at the ground level, whereas, Coccinella septempunctata, Hippodamia convergens were rarely found in the tree canopy and commonly found at the ground level. Green lacewing abundance was higher in the ground level than in the tree canopy. Brown lacewings were more abundant in the tree canopy than at the ground level. Dolichopodid and syrphid fly abundance, at the ground level increased during peak aphid abundance in the tree canopy. Application of an aqueous solution of fermenting molasses to the pecan foliage during an aphid outbreak significantly increased the abundance of ladybeetles and lacewings and significantly reduced the abundance of yellow pecan, blackmargined and black pecan aphids.

  12. Seasonal Abundance of Aphids and Aphidophagous Insects in Pecan

    Science.gov (United States)

    Dutcher, James D.; Karar, Haider; Abbas, Ghulam

    2012-01-01

    Seasonal occurrence of aphids and aphidophagous insects was monitored for six years (2006–2011) from full leaf expansion in May to leaf fall in October in “Desirable” variety pecan trees that were not treated with insecticides. Aphid outbreaks occurred two times per season, once in the spring and again in the late summer. Yellow pecan and blackmargined aphids exceeded the recommended treatment thresholds one time and black pecan aphids exceeded the recommended treatment levels three times over the six seasons. Increases in aphidophagous insect abundance coincided with aphid outbreaks in five of the six seasons. Among aphidophagous insects Harmonia axyridis and Olla v-nigrum were frequently collected in both the tree canopy and at the ground level, whereas, Coccinella septempunctata, Hippodamia convergens were rarely found in the tree canopy and commonly found at the ground level. Green lacewing abundance was higher in the ground level than in the tree canopy. Brown lacewings were more abundant in the tree canopy than at the ground level. Dolichopodid and syrphid fly abundance, at the ground level increased during peak aphid abundance in the tree canopy. Application of an aqueous solution of fermenting molasses to the pecan foliage during an aphid outbreak significantly increased the abundance of ladybeetles and lacewings and significantly reduced the abundance of yellow pecan, blackmargined and black pecan aphids. PMID:26466738

  13. Applied Genetics and Genomics in Alfalfa Breeding

    Directory of Open Access Journals (Sweden)

    E. Charles Brummer

    2012-03-01

    Full Text Available Alfalfa (Medicago sativa L., a perennial and outcrossing species, is a widely planted forage legume for hay, pasture and silage throughout the world. Currently, alfalfa breeding relies on recurrent phenotypic selection, but alternatives incorporating molecular marker assisted breeding could enhance genetic gain per unit time and per unit cost, and accelerate alfalfa improvement. Many major quantitative trait loci (QTL related to agronomic traits have been identified by family-based QTL mapping, but in relatively large genomic regions. Candidate genes elucidated from model species have helped to identify some potential causal loci in alfalfa mapping and breeding population for specific traits. Recently, high throughput sequencing technologies, coupled with advanced bioinformatics tools, have been used to identify large numbers of single nucleotide polymorphisms (SNP in alfalfa, which are being developed into markers. These markers will facilitate fine mapping of quantitative traits and genome wide association mapping of agronomic traits and further advanced breeding strategies for alfalfa, such as marker-assisted selection and genomic selection. Based on ideas from the literature, we suggest several ways to improve selection in alfalfa including (1 diversity selection and paternity testing, (2 introgression of QTL and (3 genomic selection.

  14. Field and laboratory evaluations of soybean lines against soybean aphid (Hemiptera: Aphididae).

    Science.gov (United States)

    Hesler, Louis S; Prischmann, Deirdre A; Dashiell, Kenton E

    2012-04-01

    The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is a major pest of soybean, Glycine max (L.). Merr., that significantly reduces yield in northern production areas of North America. Insecticides are widely used to control soybean aphid outbreaks, but efforts are underway to develop host plant resistance as an effective alternative management strategy. Here, previously identified resistant lines were evaluated in laboratory tests against field-collected populations of soybean aphid and in field-plot tests over 2 yr in South Dakota. Six lines previously identified with resistance to soybean aphid--Jackson, Dowling, K1639, Cobb, Palmetto and Sennari--were resistant in this study, but relatively high aphid counts on Tie-feng 8 in field plots contrasted with its previously reported resistance. Bhart-PI 165989 showed resistance in one of two laboratory tests, but it had relatively large aphid infestations in both years of field tests. Intermediate levels of soybean aphid occurred in field plots on lines previously shown to have strong (Sugao Zairai, PI 230977, and D75-10169) or moderate resistance to soybean aphid (G93-9223, Bragg, Braxton, and Tracy-M). Sugao Zairai also failed to have a significant proportion of resistant plants in two laboratory tests against aphids field-collected in 2008, but it was resistant in laboratory tests with aphids collected in 2002, 2005, and 2006. Overall, results showed that lines with Rag (i.e., Jackson) or Rag1 gene (i.e., Dowling) had low aphid numbers, whereas lines with Rag2 (i.e., Sugao Zairai, Sennari) had mixed results. Collectively, responses of soybean aphid populations in laboratory and field tests in 2008 resembled a virulence pattern reported previously for biotype 3 soybean aphids, but virulence in soybean aphid populations was variable and dynamic over years of the study. These results, coupled with previous reports of biotypes virulent to Rag1, suggest that deployment of lines with a single aphid

  15. The Potato Aphid Salivary Effector Me47 Is a Glutathione-S-Transferase Involved in Modifying Plant Responses to Aphid Infestation

    OpenAIRE

    Kettles, Graeme J.; Kaloshian, Isgouhi

    2016-01-01

    Polyphagous aphid pests cause considerable economic damage to crop plants, primarily through the depletion of photoassimilates and transfer of viruses. The potato aphid (Macrosiphum euphorbiae) is a notable pest of solanaceous crops, however, the molecular mechanisms that underpin the ability to colonize these hosts are unknown. It has recently been demonstrated that like other aphid species, M. euphorbiae injects a battery of salivary proteins into host plants during feeding. It is speculate...

  16. Terpenoid biosynthesis in Arabidopsis attacked by caterpillars and aphids: effects of aphid density on the attraction of a caterpillar parasitoid.

    Science.gov (United States)

    Kroes, Anneke; Weldegergis, Berhane T; Cappai, Francesco; Dicke, Marcel; van Loon, Joop J A

    2017-12-01

    One of the responses of plants to insect attack is the production of volatile organic compounds that mediate indirect defence of plants by attracting natural enemies of the attacking herbivores. Herbivore-induced plant volatiles (HIPVs) include terpenoids that play key roles in the attraction of natural enemies. Crosstalk between phytohormonal signalling pathways is well known to affect the regulation of plant defences, including the emission of HIPVs. Thus, simultaneous feeding on the same plant by caterpillars and aphids, can affect the attraction of parasitoids by the plant compared to single insect attack. The role of aphid density in the regulation of HIPV emission by plants under dual attack has not been studied previously. Here, we investigated the attraction of Diadegma semiclausum, a parasitoid of the Diamondback moth Plutella xylostella, to volatiles emitted by Arabidopsis thaliana plants, simultaneously attacked by host caterpillars, and by the non-host aphid Brevicoryne brassicae. Our study shows that the effect of aphid infestation on parasitoid attraction is influenced by the density of the aphids. Biosynthesis and emission of (E,E)-α-farnesene could be linked to the observed preference of D. semiclausum parasitoids for the HIPV blend emitted by plants dually infested by caterpillars and aphids at a high density compared to dually infested plants with a low aphid density. Parasitoids such as D. semiclausum are important enemies of herbivorous insects and a better understanding of how plants express indirect defence mechanisms in response to multiple insect attack will provide important knowledge on plant-herbivore-parasitoid interactions under multiple stress conditions.

  17. Elevated atmospheric carbon dioxide concentrations promote ant tending of aphids.

    Science.gov (United States)

    Kremer, Jenni M M; Nooten, Sabine S; Cook, James M; Ryalls, James M W; Barton, Craig V M; Johnson, Scott N

    2018-04-27

    Animal mutualisms, which involve beneficial interactions between individuals of different species, are common in nature. Insect-insect mutualism, for example, is widely regarded as a keystone ecological interaction. Some mutualisms are anticipated to be modified by climate change, but the focus has largely been on plant-microbe and plant-animal mutualisms rather than those between animals. Ant-aphid mutualisms, whereby ants tend aphids to harvest their honeydew excretions and, in return, provide protection for the aphids, are widespread. The mutualism is heavily influenced by the quality and quantity of honeydew produced by aphids, which is directly affected by host plant quality. As predicted increases in concentrations of atmospheric carbon dioxide (eCO 2 ) are widely reported to affect plant nutritional chemistry, this may also alter honeydew quality and hence the nature of ant-aphid mutualisms. Using glasshouse chambers and field-based open-top chambers, we determined the effect of eCO 2 on the growth and nutritional quality (foliar amino acids) of lucerne (Medicago sativa). We determined how cowpea aphid (Aphis craccivora) populations and honeydew production were impacted when feeding on such plants and how this affected the tending behaviour of ants (Iridomyrmex sp.). eCO 2 stimulated plant growth but decreased concentrations of foliar amino acids by 29% and 14% on aphid-infested plants and aphid-free plants, respectively. Despite the deterioration in host plant quality under eCO 2 , aphids maintained performance and populations were unchanged by eCO 2 . Aphids induced higher concentrations of amino acids (glutamine, asparagine, glutamic acid and aspartic acid) important for endosymbiont-mediated synthesis of essential amino acids. Aphids feeding under eCO 2 also produced over three times more honeydew than aphids feeding under ambient CO 2 , suggesting they were imbibing more phloem sap at eCO 2 . The frequency of ant tending of aphids more than doubled in

  18. Loss of aphid transmissibility of plum pox virus isolates

    NARCIS (Netherlands)

    Kamenova, I.; Lohuis, H.; Peters, D.

    2002-01-01

    The aphid transmissibility of seven Plum pox virus (PPV) isolates and the amino acid sequences of their coat proteins were analysed Two aphid transmissible isolates PPV-A and PPV-P contained the DAG amino triplet, while DAL or NAG replaced this triplet in the coat proteins of non-aphid transmissible

  19. Parasitic wasp responses to symbiont-based defense in aphids

    Directory of Open Access Journals (Sweden)

    Oliver Kerry M

    2012-02-01

    Full Text Available Abstract Background Recent findings indicate that several insect lineages receive protection against particular natural enemies through infection with heritable symbionts, but little is yet known about whether enemies are able to discriminate and respond to symbiont-based defense. The pea aphid, Acyrthosiphon pisum, receives protection against the parasitic wasp, Aphidius ervi, when infected with the bacterial symbiont Hamiltonella defensa and its associated bacteriophage APSE (Acyrthosiphon pisum secondary endosymbiont. Internally developing parasitoid wasps, such as A. ervi, use maternal and embryonic factors to create an environment suitable for developing wasps. If more than one parasitoid egg is deposited into a single aphid host (superparasitism, then additional complements of these factors may contribute to the successful development of the single parasitoid that emerges. Results We performed experiments to determine if superparasitism is a tactic allowing wasps to overcome symbiont-mediated defense. We found that the deposition of two eggs into symbiont-protected aphids significantly increased rates of successful parasitism relative to singly parasitized aphids. We then conducted behavioral assays to determine whether A. ervi selectively superparasitizes H. defensa-infected aphids. In choice tests, we found that A. ervi tends to deposit a single egg in uninfected aphids, but two or more eggs in H. defensa-infected aphids, indicating that oviposition choices may be largely determined by infection status. Finally, we identified differences in the quantity of the trans-β-farnesene, the major component of aphid alarm pheromone, between H. defensa-infected and uninfected aphids, which may form the basis for discrimination. Conclusions Here we show that the parasitic wasp A. ervi discriminates among symbiont-infected and uninfected aphids, and changes its oviposition behavior in a way that increases the likelihood of overcoming symbiont

  20. Detection of new viruses in alfalfa, weeds and cultivated plants growing adjacent to alfalfa fields in Saudi Arabia.

    Science.gov (United States)

    Al-Shahwan, I M; Abdalla, O A; Al-Saleh, M A; Amer, M A

    2017-09-01

    A total of 1368 symptomatic plant samples showing different virus-like symptoms such as mottling, chlorosis, mosaic, yellow mosaic, vein clearing and stunting were collected from alfalfa, weed and cultivated plant species growing in vicinity of alfalfa fields in five principal regions of alfalfa production in Saudi Arabia. DAS-ELISA test indicated occurrence of 11 different viruses in these samples, 10 of which were detected for the first time in Saudi Arabia. Eighty percent of the alfalfa samples and 97.5% of the weed and cultivated plants samples were found to be infected with one or more of these viruses. Nine weed plant species were found to harbor these viruses namely, Sonchus oleraceus, Chenopodium spp., Hibiscus spp., Cichorium intybus , Convolvulus arvensis , Malva parviflora , Rubus fruticosus , Hippuris vulgaris , and Flaveria trinervia . These viruses were also detected in seven cultivated crop plants growing adjacent to the alfalfa fields including Vigna unguiculata , Solanum tuberosum , Solanum melongena , Phaseolus vulgaris , Cucurbita maxima , Capsicum annuum , and Vicia faba . The newly reported viruses together with their respective percent of detection in alfalfa, and in both weeds and cultivated crop plant species together were as follows: Bean leaf roll virus (BLRV) {12.5 and 4.5%}, Lucerne transient streak virus (LTSV) {2.9 and 3.5%}, Bean yellow mosaic virus (BYMV) {1.4 and 4.5%}, Bean common mosaic virus (BCMV) {1.2 and 4.5%}, Red clover vein mosaic virus (RCVMV) {1.2 and 4%}, White clover mosaic virus (WCIMV) {1.0 and 5%}, Cucumber mosaic virus (CMV) {0.8 and 3%}, Pea streak virus (PeSV) {0.4 and 4.5%} and Tobacco streak virus (TSV) {0.3 and 2.5%}. Alfalfa mosaic virus (AMV), the previously reported virus in alfalfa, had the highest percentage of detection in alfalfa accounting for 58.4% and 62.8% in the weeds and cultivated plants. Peanut stunt virus (PSV) was also detected for the first time in Saudi Arabia with a 66.7% of infection in 90

  1. Detection of new viruses in alfalfa, weeds and cultivated plants growing adjacent to alfalfa fields in Saudi Arabia

    Directory of Open Access Journals (Sweden)

    I.M. Al-Shahwan

    2017-09-01

    Full Text Available A total of 1368 symptomatic plant samples showing different virus-like symptoms such as mottling, chlorosis, mosaic, yellow mosaic, vein clearing and stunting were collected from alfalfa, weed and cultivated plant species growing in vicinity of alfalfa fields in five principal regions of alfalfa production in Saudi Arabia. DAS-ELISA test indicated occurrence of 11 different viruses in these samples, 10 of which were detected for the first time in Saudi Arabia. Eighty percent of the alfalfa samples and 97.5% of the weed and cultivated plants samples were found to be infected with one or more of these viruses. Nine weed plant species were found to harbor these viruses namely, Sonchus oleraceus, Chenopodium spp., Hibiscus spp., Cichorium intybus, Convolvulus arvensis, Malva parviflora, Rubus fruticosus, Hippuris vulgaris, and Flaveria trinervia. These viruses were also detected in seven cultivated crop plants growing adjacent to the alfalfa fields including Vigna unguiculata, Solanum tuberosum, Solanum melongena, Phaseolus vulgaris, Cucurbita maxima, Capsicum annuum, and Vicia faba. The newly reported viruses together with their respective percent of detection in alfalfa, and in both weeds and cultivated crop plant species together were as follows: Bean leaf roll virus (BLRV {12.5 and 4.5%}, Lucerne transient streak virus (LTSV {2.9 and 3.5%}, Bean yellow mosaic virus (BYMV {1.4 and 4.5%}, Bean common mosaic virus (BCMV {1.2 and 4.5%}, Red clover vein mosaic virus (RCVMV {1.2 and 4%}, White clover mosaic virus (WCIMV {1.0 and 5%}, Cucumber mosaic virus (CMV {0.8 and 3%}, Pea streak virus (PeSV {0.4 and 4.5%} and Tobacco streak virus (TSV {0.3 and 2.5%}. Alfalfa mosaic virus (AMV, the previously reported virus in alfalfa, had the highest percentage of detection in alfalfa accounting for 58.4% and 62.8% in the weeds and cultivated plants. Peanut stunt virus (PSV was also detected for the first time in Saudi Arabia with a 66.7% of infection in 90

  2. A highly infective plant-associated bacterium influences reproductive rates in pea aphids.

    Science.gov (United States)

    Hendry, Tory A; Clark, Kelley J; Baltrus, David A

    2016-02-01

    Pea aphids, Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen, Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we used P. syringae infection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction.

  3. A highly infective plant-associated bacterium influences reproductive rates in pea aphids

    Science.gov (United States)

    Hendry, Tory A.; Clark, Kelley J.; Baltrus, David A.

    2016-01-01

    Pea aphids, Acyrthosiphon pisum, have the potential to increase reproduction as a defence against pathogens, though how frequently this occurs or how infection with live pathogens influences this response is not well understood. Here we determine the minimum infective dose of an environmentally common bacterium and possible aphid pathogen, Pseudomonas syringae, to determine the likelihood of pathogenic effects to pea aphids. Additionally, we used P. syringae infection to investigate how live pathogens may alter reproductive rates. We found that oral bacterial exposure decreased subsequent survival of aphids in a dose-dependent manner and we estimate that ingestion of less than 10 bacterial cells is sufficient to increase aphid mortality. Pathogen dose was positively related to aphid reproduction. Aphids exposed to low bacterial doses showed decreased, although statistically indistinguishable, fecundity compared to controls. Aphids exposed to high doses reproduced significantly more than low dose treatments and also more, but not significantly so, than controls. These results are consistent with previous studies suggesting that pea aphids may use fecundity compensation as a response to pathogens. Consequently, even low levels of exposure to a common plant-associated bacterium may therefore have significant effects on pea aphid survival and reproduction. PMID:26998321

  4. Altruistic defence behaviours in aphids

    Directory of Open Access Journals (Sweden)

    Brodeur Jacques

    2010-01-01

    Full Text Available Abstract Background Altruistic anti-predatory behaviours pose an evolutionary problem because they are costly to the actor and beneficial to the recipients. Altruistic behaviours can evolve through indirect fitness benefits when directed toward kin. The altruistic nature of anti-predatory behaviours is often difficult to establish because the actor can obtain direct fitness benefits, or the behaviour could result from selfish coercion by others, especially in eusocial animals. Non-eusocial parthenogenetically reproducing aphids form colonies of clone-mates, which are ideal to test the altruistic nature of anti-predatory defence behaviours. Many aphids release cornicle secretions when attacked by natural enemies such as parasitoids. These secretions contain an alarm pheromone that alerts neighbours (clone-mates of danger, thereby providing indirect fitness benefits to the actor. However, contact with cornicle secretions also hampers an attacker and could provide direct fitness to the actor. Results We tested the hypothesis that cornicle secretions are altruistic by assessing direct and indirect fitness consequences of smearing cornicle secretions onto an attacker, and by manipulating the number of clone-mates that could benefit from the behaviour. We observed parasitoids, Aphidius rhopalosiphi, foraging singly in patches of the cereal aphid Sitobion avenae of varied patch size (2, 6, and 12 aphids. Aphids that smeared parasitoids did not benefit from a reduced probability of parasitism, or increase the parasitoids' handling time. Smeared parasitoids, however, spent proportionately more time grooming and less time foraging, which resulted in a decreased host-encounter and oviposition rate within the host patch. In addition, individual smearing rate increased with the number of clone-mates in the colony. Conclusions Cornicle secretions of aphids were altruistic against parasitoids, as they provided no direct fitness benefits to secretion

  5. Evolutionary ecology of the interactions between aphids and their parasitoids.

    Science.gov (United States)

    Le Ralec, Anne; Anselme, Caroline; Outreman, Yannick; Poirié, Marylène; van Baaren, Joan; Le Lann, Cécile; van Alphen, Jacques J-M

    2010-01-01

    Many organisms, including entomopathogenous fungi, predators or parasites, use aphids as ressources. Parasites of aphids are mostly endoparasitoid insects, i.e. insects which lay eggs inside the body of an other insect which will die as a result of their development. In this article, we review the consequences of the numerous pecularities of aphid biology and ecology for their endoparasitoids, notably the Aphidiinae (Hymenoptera: Braconidae). We first examine the various mechanisms used by aphids for defence against these enemies. We then explore the strategies used by aphidiine parasitoids to exploit their aphid hosts. Finally, we consider the responses of both aphids and parasitoids to ecological constraints induced by seasonal cycles and to environmental variations linked to host plants and climate. The fundamental and applied interest of studying these organisms is discussed. Copyright 2010 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  6. Aphid facultative symbionts reduce survival of the predatory lady beetle Hippodamia convergens

    Science.gov (United States)

    2014-01-01

    Background Non-essential facultative endosymbionts can provide their hosts with protection from parasites, pathogens, and predators. For example, two facultative bacterial symbionts of the pea aphid (Acyrthosiphon pisum), Serratia symbiotica and Hamiltonella defensa, protect their hosts from parasitism by two species of parasitoid wasp. Previous studies have not explored whether facultative symbionts also play a defensive role against predation in this system. We tested whether feeding on aphids harboring different facultative symbionts affected the fitness of an aphid predator, the lady beetle Hippodamia convergens. Results While these aphid faculative symbionts did not deter lady beetle feeding, they did decrease survival of lady beetle larvae. Lady beetle larvae fed a diet of aphids with facultative symbionts had significantly reduced survival from egg hatching to pupation and therefore had reduced survival to adult emergence. Additionally, lady beetle adults fed aphids with facultative symbionts were significantly heavier than those fed facultative symbiont-free aphids, though development time was not significantly different. Conclusions Aphids reproduce clonally and are often found in large groups. Thus, aphid symbionts, by reducing the fitness of the aphid predator H. convergens, may indirectly defend their hosts’ clonal descendants against predation. These findings highlight the often far-reaching effects that symbionts can have in ecological systems. PMID:24555501

  7. Genetic Engineering of Alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Wang, Dan; Khurshid, Muhammad; Sun, Zhan Min; Tang, Yi Xiong; Zhou, Mei Liang; Wu, Yan Min

    2016-01-01

    Alfalfa is excellent perennial legume forage for its extensive ecological adaptability, high nutrition value, palatability and biological nitrogen fixation. It plays a very important role in the agriculture, animal husbandry and ecological construction. It is cultivated in all continents. With the development of modern plant breeding and genetic engineering techniques, a large amount of work has been carried out on alfalfa. Here we summarize the recent research advances in genetic engineering of alfalfa breeding, including transformation, quality improvement, stress resistance and as a bioreactor. The review article can enables us to understand the research method, direction and achievements of genetic engineering technology of Alfalfa.

  8. Multiple cues for winged morph production in an aphid metacommunity.

    Directory of Open Access Journals (Sweden)

    Mohsen Mehrparvar

    Full Text Available Environmental factors can lead individuals down different developmental pathways giving rise to distinct phenotypes (phenotypic plasticity. The production of winged or unwinged morphs in aphids is an example of two alternative developmental pathways. Dispersal is paramount in aphids that often have a metapopulation structure, where local subpopulations frequently go extinct, such as the specialized aphids on tansy (Tanacetum vulgare. We conducted various experiments to further understand the cues involved in the production of winged dispersal morphs by the two dominant species of the tansy aphid metacommunity, Metopeurum fuscoviride and Macrosiphoniella tanacetaria. We found that the ant-tended M. fuscoviride produced winged individuals predominantly at the beginning of the season while the untended M. tanacetaria produced winged individuals throughout the season. Winged mothers of both species produced winged offspring, although in both species winged offspring were mainly produced by unwinged females. Crowding and the presence of predators, effects already known to influence wing production in other aphid species, increased the percentage of winged offspring in M. tanacetaria, but not in M. fuscoviride. We find there are also other factors (i.e. temporal effects inducing the production of winged offspring for natural aphid populations. Our results show that the responses of each aphid species are due to multiple wing induction cues.

  9. Social aggregation in pea aphids: experiment and random walk modeling.

    Directory of Open Access Journals (Sweden)

    Christa Nilsen

    Full Text Available From bird flocks to fish schools and ungulate herds to insect swarms, social biological aggregations are found across the natural world. An ongoing challenge in the mathematical modeling of aggregations is to strengthen the connection between models and biological data by quantifying the rules that individuals follow. We model aggregation of the pea aphid, Acyrthosiphon pisum. Specifically, we conduct experiments to track the motion of aphids walking in a featureless circular arena in order to deduce individual-level rules. We observe that each aphid transitions stochastically between a moving and a stationary state. Moving aphids follow a correlated random walk. The probabilities of motion state transitions, as well as the random walk parameters, depend strongly on distance to an aphid's nearest neighbor. For large nearest neighbor distances, when an aphid is essentially isolated, its motion is ballistic with aphids moving faster, turning less, and being less likely to stop. In contrast, for short nearest neighbor distances, aphids move more slowly, turn more, and are more likely to become stationary; this behavior constitutes an aggregation mechanism. From the experimental data, we estimate the state transition probabilities and correlated random walk parameters as a function of nearest neighbor distance. With the individual-level model established, we assess whether it reproduces the macroscopic patterns of movement at the group level. To do so, we consider three distributions, namely distance to nearest neighbor, angle to nearest neighbor, and percentage of population moving at any given time. For each of these three distributions, we compare our experimental data to the output of numerical simulations of our nearest neighbor model, and of a control model in which aphids do not interact socially. Our stochastic, social nearest neighbor model reproduces salient features of the experimental data that are not captured by the control.

  10. Alfalfa breeding benefits from genomics of Medicago truncatula

    Directory of Open Access Journals (Sweden)

    Žilije Bernadet

    2010-01-01

    Full Text Available International programs aim at developing knowledge and tools in the model species Medicago truncatula. Genetic resources, DNA sequences, markers, genetic and physical maps are now publicly available. These efforts contribute to improve breeding schemes of crop species such as alfalfa. However, transfer of information from M. truncatula to alfalfa is not straightforward. The article reviews the gain given by the model species to better analyze genetic determinism of breeding traits in alfalfa. It also shows that investments in alfalfa genomics (DNA sequences, SNP development are needed to benefit from the model species.

  11. Health status of alfalfa leafcutting bee larvae (Hymenoptera: Megachilidae) in United States alfalfa seed fields.

    Science.gov (United States)

    James, R R; Pitts-Singer, T L

    2013-12-01

    We conducted a broad geographic survey in the northwestern United States to quantify production losses in the alfalfa leafcutting bee (Megachile rotundata (F.), Hymenoptera: Megachilidae), a solitary pollinator used extensively in alfalfa seed production. Viable larvae were found in only 47.1% of the nest cells collected at the end of the season. Most of the rest of the cells contained pollen balls (typified by a provision but no larva; 16.7%), unknown causes of mortality (15.5%), or larvae killed by chalkbrood (8.0%). Prevalence of pollen balls was correlated positively with bee release rates and negatively with alfalfa stand age. The unknown mortality was correlated with the U.S. Department of Agriculture-Plant Hardiness Zone, and thus, some of the mortality may be caused by high temperature extremes, although the nesting season degree-days were not correlated with this mortality. Chalkbrood prevalence was correlated with possible nesting-resource or crowding-related factors, such as the number of bees released per hectare and the number of shelters used, but not with nesting board disinfection practices. Vapona is used to control parasitoids when the parent bees are incubated before release, and use of this fumigant was associated with an increase in both chalkbrood and diapausing offspring, although any reason for these correlations are unknown. This survey quantifies the variation in the quality of alfalfa leafcutting bee cocoons produced across much of the U.S. alfalfa seed production area.

  12. Aphid Identification and Counting Based on Smartphone and Machine Vision

    Directory of Open Access Journals (Sweden)

    Suo Xuesong

    2017-01-01

    Full Text Available Exact enumeration of aphids before the aphids outbreak can provide basis for precision spray. This paper designs counting software that can be run on smartphones for real-time enumeration of aphids. As a first step of the method used in this paper, images of the yellow sticky board that is aiming to catch insects are segmented from complex background by using GrabCut method; then the images will be normalized by perspective transformation method. The second step is the pretreatment on the images; images of aphids will be segmented by using OSTU threshold method after the effect of random illumination is eliminated by single image difference method. The last step of the method is aphids’ recognition and counting according to area feature of aphids after extracting contours of aphids by contour detection method. At last, the result of the experiment proves that the effect of random illumination can be effectively eliminated by using single image difference method. The counting accuracy in greenhouse is above 95%, while it can reach 92.5% outside. Thus, it can be seen that the counting software designed in this paper can realize exact enumeration of aphids under complicated illumination which can be used widely. The design method proposed in this paper can provide basis for precision spray according to its effective detection insects.

  13. Alfalfa stem tissues: Cell wall deposition, composition, and degradability

    NARCIS (Netherlands)

    Jung, H.G.; Engels, F.M.

    2002-01-01

    Declining cell wall degradability of alfalfa (Medicago sativa L.) stems with maturation limits the nutritional value of alfalfa for ruminants. This study characterized changes in cell wall concentration, composition, and degradability by rumen microbes resulting from alfalfa stem tissue

  14. Indian Bt cotton varieties do not affect the performance of cotton aphids.

    Directory of Open Access Journals (Sweden)

    Nora C Lawo

    Full Text Available Cotton varieties expressing Cry proteins derived from the soil bacterium Bacillus thuringiensis (Bt are grown worldwide for the management of pest Lepidoptera. To prevent non-target pest outbreaks and to retain the biological control function provided by predators and parasitoids, the potential risk that Bt crops may pose to non-target arthropods is addressed prior to their commercialization. Aphids play an important role in agricultural systems since they serve as prey or host to a number of predators and parasitoids and their honeydew is an important energy source for several arthropods. To explore possible indirect effects of Bt crops we here examined the impact of Bt cotton on aphids and their honeydew. In climate chambers we assessed the performance of cotton aphids, Aphis gossypii Glover (Hemiptera: Aphididae when grown on three Indian Bt (Cry1Ac cotton varieties (MECH 12, MECH 162, MECH 184 and their non-transformed near isolines. Furthermore, we examined whether aphids pick up the Bt protein and analyzed the sugar composition of aphid honeydew to evaluate its suitability for honeydew-feeders. Plant transformation did not have any influence on aphid performance. However, some variation was observed among the three cotton varieties which might partly be explained by the variation in trichome density. None of the aphid samples contained Bt protein. As a consequence, natural enemies that feed on aphids are not exposed to the Cry protein. A significant difference in the sugar composition of aphid honeydew was detected among cotton varieties as well as between transformed and non-transformed plants. However, it is questionable if this variation is of ecological relevance, especially as honeydew is not the only sugar source parasitoids feed on in cotton fields. Our study allows the conclusion that Bt cotton poses a negligible risk for aphid antagonists and that aphids should remain under natural control in Bt cotton fields.

  15. Influences of pea morphology and interacting factors on pea aphid (Homoptera: Aphididae) reproduction.

    Science.gov (United States)

    Buchman, N; Cuddington, K

    2009-08-01

    It has been claimed that plant architecture can alter aphid reproductive rates, but the mechanism driving this effect has not been identified. We studied interactions between plant architecture, aphid density, environmental conditions, and nutrient availability on the reproduction of pea aphids [Acyrthosiphon pisum (Harris)] using four near-isogenic peas (Pisum sativum L.) that differ in morphology. Manipulations of aphid density (1, 5, and 10 adults per plant) allowed us to examine any effects of plant morphology on crowding and consequently reproduction. Pea morphology per se did not alter pea aphid crowding, as measured by mean nearest neighbor distance, and there was no effect on reproduction. In addition, reproduction increased with increasing adult density, indicating positive density dependence. In a separate experiment, peas were fertilized to determine whether differences between nutrient availability of the four different morphologies might drive any observed differences in aphid reproduction. Although plant nitrogen content was altered by fertilization treatments, this did not have an impact on aphid reproduction. Greenhouse experiments, however, suggested that pea morphology can interact with environmental conditions to reduce aphid reproduction under some conditions. We conclude that plant morphology only influences aphid reproduction when environmental conditions are less than optimal.

  16. Whitefly and aphid inducible promoters from Arabidopsis thaliana L.

    Indian Academy of Sciences (India)

    Aphids, whitefly, inducible promoter, sap sucking insects, biotic stress. Whitefly and aphid ..... pathway related genes in cotton plants (Dubey et al. 2013). ... and coordination of work, data analysis and interpretation, and revised the article.

  17. Soybean Aphid Infestation Induces Changes in Fatty Acid Metabolism in Soybean.

    Directory of Open Access Journals (Sweden)

    Charles Kanobe

    Full Text Available The soybean aphid (Aphis glycines Matsumura is one of the most important insect pests of soybeans in the North-central region of the US. It has been hypothesized that aphids avoid effective defenses by inhibition of jasmonate-regulated plant responses. Given the role fatty acids play in jasmonate-induced plant defenses, we analyzed the fatty acid profile of soybean leaves and seeds from aphid-infested plants. Aphid infestation reduced levels of polyunsaturated fatty acids in leaves with a concomitant increase in palmitic acid. In seeds, a reduction in polyunsaturated fatty acids was associated with an increase in stearic acid and oleic acid. Soybean plants challenged with the brown stem rot fungus or with soybean cyst nematodes did not present changes in fatty acid levels in leaves or seeds, indicating that the changes induced by aphids are not a general response to pests. One of the polyunsaturated fatty acids, linolenic acid, is the precursor of jasmonate; thus, these changes in fatty acid metabolism may be examples of "metabolic hijacking" by the aphid to avoid the induction of effective defenses. Based on the changes in fatty acid levels observed in seeds and leaves, we hypothesize that aphids potentially induce interference in the fatty acid desaturation pathway, likely reducing FAD2 and FAD6 activity that leads to a reduction in polyunsaturated fatty acids. Our data support the idea that aphids block jasmonate-dependent defenses by reduction of the hormone precursor.

  18. Bacteria may contribute to distant species recognition in ant-aphid mutualistic relationships.

    Science.gov (United States)

    Fischer, Christophe Y; Detrain, Claire; Thonart, Philippe; Haubruge, Eric; Francis, Frédéric; Verheggen, François J; Lognay, Georges C

    2017-04-01

    Mutualistic interactions between ant and aphid species have been the subject of considerable historical and contemporary investigations, the primary benefits being cleaning and protection for the aphids and carbohydrate-rich honeydew for the ants. Questions remained, however, as to the volatile semiochemical factor influencing this relationship. A recent study highlighted the role of bacterial honeydew volatile compounds in ant attraction. Here, ant's ability to distantly discriminate 2 aphid species was investigated based on bacterial honeydew semiochemicals emissions using a two-way olfactometer. Both the mutualistic aphid Aphis fabae L. and the nonmyrmecophilous aphid Acyrthosiphon pisum Harris were found to be attractive for the ant Lasius niger L. The level of attraction was similar in both assays (control vs. one of the aphid species). However, when given a choice between these 2 aphid species, ants showed a significant preference for Aphis fabae. Honeydew volatiles, mostly from bacterial origins, are known to be a key element in ant attraction. Using the same olfactometry protocol, the relative attractiveness of volatiles emitted by honeydews collected from each aphid species and by bacteria isolated from each honeydew was investigated. Again, ants significantly preferred volatiles released by Aphis fabae honeydew and bacteria. This information suggests that microbial honeydew volatiles enable ants to distantly discriminate aphid species. These results strengthen the interest of studying the occurrence and potential impact of microorganisms in insect symbioses. © 2015 Institute of Zoology, Chinese Academy of Sciences.

  19. THE ROLE OF BACTERIAL SYMBIONTS IN AMINO ACID COMPOSITION OF BLACK BEAN APHIDS

    Institute of Scientific and Technical Information of China (English)

    MingGan; De-ChengDing; Xue-xiaMiao

    2003-01-01

    To evaluate the role of bacterial symbionts ( Buchnera spp. ) in the black bean aphids ( Aphis craccivora Koch), the aphids were treated with the antibiotic, rifampicin, to eliminate their intracellular symbiotic bacteria. Analysis of protein and amino acid concentration in 7-day-old of aposymbiotic aphids showed that the total protein content per mg fresh weight was significantly reduced by 29 %, but free amino acid titers were increased by 17% . The ratio of the essential amino acids was in general only around 20% essential amino acids in phloem sap of broad bean, whereas it was 44% and 37% in symbiotic and aposymbiotic aphids, respectively,suggesting that the composition of the free amino acids was unbalanced. For example, the essential amino acid,threonine represented 21. 6% of essential amino acids in symbiotic aphids, but it was only 16.7% in aposymbiotic aphids. Likewise, two nonessential amino acids, tyrosine and serine, represented 8.9% and 5.6% of total amino acids in symbiontic aphids, respectively, but they enhanced to 21.1% and 13.6% in aposymbiotic aphids. It seems likely that the elevated free amino acid concentration in aposymbiotic aphids was caused by the limited protein anabolism as the result of the unbalanced amino acid composition.

  20. Cereal aphid colony turnover and persistence in winter wheat.

    Directory of Open Access Journals (Sweden)

    Linton Winder

    Full Text Available An understanding of spatial and temporal processes in agricultural ecosystems provides a basis for rational decision-making with regards to the management and husbandry of crops, supporting the implementation of integrated farming strategies. In this study we investigated the spatial and temporal distribution of aphid pests (Sitobion avenae and Metopolophium dirhodum within winter wheat fields. Using an intensive sampling programme we investigated distributions at both the small (single shoot and large (field scales. Within two fields, a grid with 82 locations was established (area 120 m by 168 m. At each location, 25 shoots were individually marked and aphid counts by observation conducted on 21 and 22 occasions as the crop matured, resulting in 43,050 and 45,100 counts being conducted in the two fields respectively. We quantified field scale spatial distributions, demonstrating that spatial pattern generally emerged, with temporal stability being both species- and field- dependent. We then measured turnover of colonies at the small (individual shoot and large (field scales by comparing consecutive pairs of sampling occasions. Four turnover categories were defined: Empty (no aphids recorded on either occasion; Colonised (aphids recorded on the second occasion but not the first; Extinction (aphids recorded on the first occasion but not the second; Stable (aphids recorded on both occasions. At the field scale, population stability soon established, but, at the small scale there was a consistently high proportion of unoccupied shoots with considerable colonisation and extinction and low stability. The redistribution of aphids within the crop at the local scale is a vulnerability which could be used to disrupt population development--by mediating exposure to ground-active natural enemies and by incurring a metabolic cost caused by the physiological demands to re-establish on a nearby host plant.

  1. Do Aphids Alter Leaf Surface Temperature Patterns During Early Infestation?

    Directory of Open Access Journals (Sweden)

    Thomas Cahon

    2018-03-01

    Full Text Available Arthropods at the surface of plants live in particular microclimatic conditions that can differ from atmospheric conditions. The temperature of plant leaves can deviate from air temperature, and leaf temperature influences the eco-physiology of small insects. The activity of insects feeding on leaf tissues, may, however, induce changes in leaf surface temperatures, but this effect was only rarely demonstrated. Using thermography analysis of leaf surfaces under controlled environmental conditions, we quantified the impact of presence of apple green aphids on the temperature distribution of apple leaves during early infestation. Aphids induced a slight change in leaf surface temperature patterns after only three days of infestation, mostly due to the effect of aphids on the maximal temperature that can be found at the leaf surface. Aphids may induce stomatal closure, leading to a lower transpiration rate. This effect was local since aphids modified the configuration of the temperature distribution over leaf surfaces. Aphids were positioned at temperatures near the maximal leaf surface temperatures, thus potentially experiencing the thermal changes. The feedback effect of feeding activity by insects on their host plant can be important and should be quantified to better predict the response of phytophagous insects to environmental changes.

  2. National Plant Diagnostic Network, Taxonomic training videos: Aphids under the microscope - overview

    Science.gov (United States)

    Training is a critical part of aphid (Hemiptera: Aphididae) identification. This training video provides provides an overview of general aphid morphology by using a compound microscope. The narrator discusses and highlights structures on the aphid that are important to make a species identification....

  3. Ecological effects of aphid abundance, genotypic variation, and contemporary evolution on plants.

    Science.gov (United States)

    Turley, Nash E; Johnson, Marc T J

    2015-07-01

    Genetic variation and contemporary evolution within populations can shape the strength and nature of species interactions, but the relative importance of these forces compared to other ecological factors is unclear. We conducted a field experiment testing the effects of genotypic variation, abundance, and presence/absence of green peach aphids (Myzus persicae) on the growth, leaf nitrogen, and carbon of two plant species (Brassica napus and Solanum nigrum). Aphid genotype affected B. napus but not S. nigrum biomass explaining 20 and 7% of the total variation, respectively. Averaging across both plant species, the presence/absence of aphids had a 1.6× larger effect size (Cohen's d) than aphid genotype, and aphid abundance had the strongest negative effects on plant biomass explaining 29% of the total variation. On B. napus, aphid genotypes had different effects on leaf nitrogen depending on their abundance. Aphids did not influence leaf nitrogen in S. nigrum nor leaf carbon in either species. We conducted a second experiment in the field to test whether contemporary evolution could affect plant performance. Aphid populations evolved in as little as five generations, but the rate and direction of this evolution did not consistently vary between plant species. On one host species (B. napus), faster evolving populations had greater negative effects on host plant biomass, with aphid evolutionary rate explaining 23% of the variation in host plant biomass. Together, these results show that genetic variation and evolution in an insect herbivore can play important roles in shaping host plant ecology.

  4. Aphid Transmission of the Ontario Isolate of Plum Pox Virus.

    Science.gov (United States)

    Lowery, D Thomas; Vickers, Patricia M; Bittner, Lori A; Stobbs, Lorne W; Foottit, Robert G

    2015-10-01

    Utilization of timed virus acquisition access probes in studies of plum pox virus (PPV) transmission by aphids demonstrated that endemic species transmitted the virus readily from plum, Prunus domestica (L.) Batsch; peach, P. persica (L.); or dwarf flowering almond, P. glandulosa Thunberg., to peach seedlings. The green peach aphid, Myzus persicae (Sulzer), was shown to be the most efficient vector. Acquisition of virus by green peach aphids from infected peach leaves resulted in 18-28% infected peach seedlings, while aphids previously fed on infected leaves of plum transferred virus to 36% of peach seedlings. Although the spirea aphid, Aphis spiraecola (Patch), was a less efficient vector than M. persicae it is perhaps more important for the spread of PPV due to its greater abundance and occurrence earlier in the season when peach trees are thought to be more susceptible to infection. Virus transmission rates varied depending on the virus source and healthy test plant species. In contrast to many previous studies, aphid inoculation of the experimental host Nicotiana benthamiana Domin occurred at a low rate, never exceeding 4%. Acquisition of PPV by M. persicae from infected peach fruit was greatly reduced compared with acquisition from leaves. The results of this research indicate that the Ontario isolate of PPV-D is readily transmissible by aphids to peach and natural spread of the virus needs to be considered in future management or eradication programs. © Her Majesty in Right of Canada, as represented by the Minister of Agriculture and Agri-Food Canada. Published by Oxford University Press on behalf of Entomological Society of America.

  5. EFFICACY OF IMIDACLOPRID (CONFIDOR 200 SL AGAINST APHIDS INFESTING WHEAT CROP

    Directory of Open Access Journals (Sweden)

    N Joshi

    2010-02-01

    Full Text Available Imidacloprid (Confidor 200 SL was evaluated either alone or with a fungicide (Tilt 0.01% against wheat aphids. There were seven different treatments, including an untreated control. All the treatments were replicated three times in a similar field environment. Population of wheat aphids was recorded on randomly selected five plants in each plot at different intervals, both before and after the spraying. Confidor 200 SL @ 400 ml/ha treatment was found most effective against wheat aphids. However, mixing of Confidor 200 SL @ 100 ml/ha with Tilt @ 0.01 %, was found significantly least effective for wheat aphids control.

  6. Spatial and Temporal Dynamics of Aphids (Hemiptera: Aphididae) in the Columbia Basin and Northeastern Oregon.

    Science.gov (United States)

    Klein, Mathew L; Rondon, Silvia I; Walenta, Darrin L; Zeb, Qamar; Murphy, Alexzandra F

    2017-08-01

    Aphid species, such as the potato aphid, Macrosiphum euphorbiae Thomas, and the green peach aphid, Myzus persicae Sulzer, are routinely considered the most important pests of potatoes. Potato aphid, green peach aphid, and more recently, other aphids such as the bird cherry-oat aphid Rhopalosiphum padi L. have been identified as vectors of multiple plant pathogenic viruses in potatoes. Since 2006, an area-wide trapping network consisting of ∼60 sites was developed through collaboration between researchers, extension faculty, and stakeholders, to monitor aphid populations in the Columbia Basin of Oregon (Umatilla and Morrow counties) and in northeastern Oregon (Union and Baker counties). Over a 9-yr period (2006 to 2014), aphid specimens were collected weekly using yellow bucket traps and specimens were then identified and counted to determine population levels during the growing season (May-September). Thus, aphid population data were compiled and subjected to spatial and temporal distribution analysis. Weather data, obtained from an established network of weather stations located in the monitoring areas, were used in a nonparametric multiplicative regression analysis to determine which abiotic variables may impact aphid populations. Weather conditions were characterized using confidence intervals (CIs) established based on weather data from 1999 to 2005 for each environmental variable. Aphid populations were found to have a heterogeneous distribution in most years; a few sites had high aphid populations while low numbers were observed at most sites; aphids were also found to correlate with several abiotic variables, namely, elevation, previous season temperature, and previous season dew point. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  7. New genus and species of the extinct aphid family Szelegiewicziidae and their implications for aphid evolution.

    Science.gov (United States)

    Wegierek, Piotr; Żyła, Dagmara; Homan, Agnieszka; Cai, Chenyang; Huang, Diying

    2017-10-24

    Recently, we are witnessing an increased appreciation for the importance of the fossil record in phylogenetics and testing various evolutionary hypotheses. However, this approach brings many challenges, especially for such a complex group as aphids and requires a thorough morphological analysis of the extinct groups. The extinct aphid family Szelegiewicziidae is supposed to be one of the oviparous lineages in aphid evolution. New material from the rock fossil deposits of Shar Teg (Upper Jurassic of Mongolia), Baissa (Lower Cretaceous of Siberia-Russia), and Burmese amber (Upper Cretaceous of Myanmar) allowed us to undertake a more detailed examination of the morphological features and carry out an analysis of the taxonomical composition and evolution of the family. This led us to the conclusion that evolution of the body plan and wing structure was similar in different, often not closely related groups, probably as a result of convergence. Additionally, we present a description of a new genus and two species (Tinaphis mongolica Żyła &Wegierek, sp. nov., and Feroorbis burmensis Wegierek & Huang, gen. et sp. nov.) that belong to this family.

  8. New genus and species of the extinct aphid family Szelegiewicziidae and their implications for aphid evolution

    Science.gov (United States)

    Wegierek, Piotr; Żyła, Dagmara; Homan, Agnieszka; Cai, Chenyang; Huang, Diying

    2017-12-01

    Recently, we are witnessing an increased appreciation for the importance of the fossil record in phylogenetics and testing various evolutionary hypotheses. However, this approach brings many challenges, especially for such a complex group as aphids and requires a thorough morphological analysis of the extinct groups. The extinct aphid family Szelegiewicziidae is supposed to be one of the oviparous lineages in aphid evolution. New material from the rock fossil deposits of Shar Teg (Upper Jurassic of Mongolia), Baissa (Lower Cretaceous of Siberia-Russia), and Burmese amber (Upper Cretaceous of Myanmar) allowed us to undertake a more detailed examination of the morphological features and carry out an analysis of the taxonomical composition and evolution of the family. This led us to the conclusion that evolution of the body plan and wing structure was similar in different, often not closely related groups, probably as a result of convergence. Additionally, we present a description of a new genus and two species ( Tinaphis mongolica Żyła &Wegierek, sp. nov., and Feroorbis burmensis Wegierek & Huang, gen. et sp. nov.) that belong to this family.

  9. Aphid Infestation Increases Fusarium langsethiae and T-2 and HT-2 Mycotoxins in Wheat

    Science.gov (United States)

    Drakulic, Jassy; Ajigboye, Olubukola; Swarup, Ranjan; Bruce, Toby

    2016-01-01

    ABSTRACT Fusarium langsethiae is a fungal pathogen of cereal crops that is an increasing problem in northern Europe, but much of its epidemiology is poorly understood. The species produces the mycotoxins T-2 and HT-2, which are highly toxic. It was hypothesized that grain aphids, Sitobion avenae, may transmit F. langsethiae inoculum between wheat plants, and a series of transmission experiments and volatile chemical analyses was performed to test this. Manual translocation of aphids from inoculated to uninfected hosts resulted in pathogen DNA accumulation in hosts. However, the free movement of wingless aphids from infected to healthy plants did not. The addition of winged aphids reared on F. langsethiae-inoculated wheat seedlings to wheat plants also did not achieve successful pathogen transfer. While our data suggested that aphid transmission of the pathogen was not very efficient, we observed an increase in disease when aphids were present. After seedling inoculation, an increase in pathogen DNA accumulation in seedling leaves was observed upon treatment with aphids. Furthermore, the presence of aphids on wheat plants with F. langsethiae-inoculated ears not only led to a rise in the amount of F. langsethiae DNA in infected grain but also to an increase in the concentrations of T-2 and HT-2 toxins, with more than 3-fold higher toxin levels than diseased plants without aphids. This work highlights that aphids increase the susceptibility of wheat host plants to F. langsethiae and that aphid infestation is a risk factor for accumulating increased levels of T-2 and HT-2 in wheat products. IMPORTANCE Fusarium langsethiae is shown here to cause increased contamination levels of grain with toxins produced by fungus when aphids share the host plant. This effect has also recently been demonstrated with Fusarium graminearum, yet the two fungal species show stark differences in their effect on aphid populations. In both cases, aphids improve the ability of the pathogens to

  10. Differential divergences of obligately insect-pathogenic Entomophthora species from fly and aphid hosts.

    Science.gov (United States)

    Jensen, Annette Bruun; Eilenberg, Jørgen; López Lastra, Claudia

    2009-11-01

    Three DNA regions (ITS 1, LSU rRNA and GPD) of isolates from the insect-pathogenic fungus genus Entomophthora originating from different fly (Diptera) and aphid (Hemiptera) host taxa were sequenced. The results documented a large genetic diversity among the fly-pathogenic Entomophthora and only minor differences among aphid-pathogenic Entomophthora. The evolutionary time of divergence of the fly and the aphid host taxa included cannot account for this difference. The host-driven divergence of Entomophthora, therefore, has been much greater in flies than in aphids. Host-range differences or a recent host shift to aphid are possible explanations.

  11. Lessons learned in managing alfalfa-grass mixtures

    Science.gov (United States)

    Grass-alfalfa mixtures have a number of benefits that make them attractive to producers. However, they can be problematic to establish and maintain. Research programs have made progress in understanding the benefits and challenges of alfalfa-grass mixtures. Mixtures may have greater winter survival ...

  12. Predatory behavior of Pseudodorus clavatus (Diptera, Syrphidae on aphids tended by ants

    Directory of Open Access Journals (Sweden)

    Alexandra Bächtold

    2013-12-01

    Full Text Available Predatory behavior of Pseudodorus clavatus (Diptera, Syrphidae on aphids tended by ants. In this study, we examined the interactions between myrmecophilous aphids, their ant-guards and a predatory syrphid species, Pseudodorus clavatus (F.. Larvae of this predator were found in the colonies of three aphid species: Aphis gossypii, A. spiraecola and Toxoptera sp., which were tended by eight ant species, especially Camponotus. Hoverfly larvae managed to infiltrate the aphid colonies and consume nymphs. Predator larvae exhibited inconspicuous movements and were not detected by ants which were commonly observed touching and antennating the larvae they come into contact. These results suggest that behavioral and chemical cues are involved in the infiltration and on the successful predation of syrphids upon aphids.

  13. Plant genetic variation mediates an indirect ecological effect between belowground earthworms and aboveground aphids.

    Science.gov (United States)

    Singh, Akanksha; Braun, Julia; Decker, Emilia; Hans, Sarah; Wagner, Agnes; Weisser, Wolfgang W; Zytynska, Sharon E

    2014-10-21

    Interactions between aboveground and belowground terrestrial communities are often mediated by plants, with soil organisms interacting via the roots and aboveground organisms via the shoots and leaves. Many studies now show that plant genetics can drive changes in the structure of both above and belowground communities; however, the role of plant genetic variation in mediating aboveground-belowground interactions is still unclear. We used an earthworm-plant-aphid model system with two aphid species (Aphis fabae and Acyrthosiphon pisum) to test the effect of host-plant (Vicia faba) genetic variation on the indirect interaction between the belowground earthworms (Eisenia veneta) on the aboveground aphid populations. Our data shows that host-plant variety mediated an indirect ecological effect of earthworms on generalist black bean aphids (A. fabae), with earthworms increasing aphid growth rate in three plant varieties but decreasing it in another variety. We found no effect of earthworms on the second aphid species, the pea aphid (A. pisum), and no effect of competition between the aphid species. Plant biomass was increased when earthworms were present, and decreased when A. pisum was feeding on the plant (mediated by plant variety). Although A. fabae aphids were influenced by the plants and worms, they did not, in turn, alter plant biomass. Previous work has shown inconsistent effects of earthworms on aphids, but we suggest these differences could be explained by plant genetic variation and variation among aphid species. This study demonstrates that the outcome of belowground-aboveground interactions can be mediated by genetic variation in the host-plant, but depends on the identity of the species involved.

  14. Inheritance patterns of secondary symbionts during sexual reproduction of pea aphid biotypes.

    Science.gov (United States)

    Peccoud, Jean; Bonhomme, Joël; Mahéo, Frédérique; de la Huerta, Manon; Cosson, Olivier; Simon, Jean-Christophe

    2014-06-01

    Herbivorous insects frequently harbor bacterial symbionts that affect their ecology and evolution. Aphids host the obligatory endosymbiont Buchnera, which is required for reproduction, together with facultative symbionts whose frequencies vary across aphid populations. These maternally transmitted secondary symbionts have been particularly studied in the pea aphid, Acyrthosiphon pisum, which harbors at least 8 distinct bacterial species (not counting Buchnera) having environmentally dependent effects on host fitness. In particular, these symbiont species are associated with pea aphid populations feeding on specific plants. Although they are maternally inherited, these bacteria are occasionally transferred across insect lineages. One mechanism of such nonmaternal transfer is paternal transmission to the progeny during sexual reproduction. To date, transmission of secondary symbionts during sexual reproduction of aphids has been investigated in only a handful of aphid lineages and 3 symbiont species. To better characterize this process, we investigated inheritance patterns of 7 symbiont species during sexual reproduction of pea aphids through a crossing experiment involving 49 clones belonging to 9 host-specialized biotypes, and 117 crosses. Symbiont species in the progeny were detected with diagnostic qualitative PCR at the fundatrix stage hatching from eggs and in later parthenogenetic generations. We found no confirmed case of paternal transmission of symbionts to the progeny, and we observed that maternal transmission of a particular symbiont species (Serratia symbiotica) was quite inefficient. We discuss these observations in respect to the ecology of the pea aphid. © 2013 Institute of Zoology, Chinese Academy of Sciences.

  15. The Effects of Aphid Traits on Parasitoid Host Use and Specialist Advantage

    Science.gov (United States)

    Gagic, Vesna; Petrović-Obradović, Olivera; Fründ, Jochen; Kavallieratos, Nickolas G.; Athanassiou, Christos G.; Starý, Petr; Tomanović, Željko

    2016-01-01

    Specialization is a central concept in ecology and one of the fundamental properties of parasitoids. Highly specialized parasitoids tend to be more efficient in host-use compared to generalized parasitoids, presumably owing to the trade-off between host range and host-use efficiency. However, it remains unknown how parasitoid host specificity and host-use depends on host traits related to susceptibility to parasitoid attack. To address this question, we used data from a 13-year survey of interactions among 142 aphid and 75 parasitoid species in nine European countries. We found that only aphid traits related to local resource characteristics seem to influence the trade-off between host-range and efficiency: more specialized parasitoids had an apparent advantage (higher abundance on shared hosts) on aphids with sparse colonies, ant-attendance and without concealment, and this was more evident when host relatedness was included in calculation of parasitoid specificity. More traits influenced average assemblage specialization, which was highest in aphids that are monophagous, monoecious, large, highly mobile (easily drop from a plant), without myrmecophily, habitat specialists, inhabit non-agricultural habitats and have sparse colonies. Differences in aphid wax production did not influence parasitoid host specificity and host-use. Our study is the first step in identifying host traits important for aphid parasitoid host specificity and host-use and improves our understanding of bottom-up effects of aphid traits on aphid-parasitoid food web structure. PMID:27309729

  16. A Genetic Survey of Pyrethroid Insecticide Resistance in Aphids in New Brunswick, Canada, with Particular Emphasis on Aphids as Vectors of Potato virus Y.

    Science.gov (United States)

    MacKenzie, Tyler D B; Arju, Irin; Poirier, René; Singh, Mathuresh

    2018-05-28

    Aphids are viral vectors in potatoes, most importantly of Potato virus Y (PVY), and insecticides are frequently used to reduce viral spread during the crop season. Aphids collected from the potato belt of New Brunswick, Canada, in 2015 and 2016 were surveyed for known and novel mutations in the Na-channel (para) gene, coding for the target of synthetic pyrethroid insecticides. Specific genetic mutations known to confer resistance (kdr and skdr) were found in great abundance in Myzus persicae (Sulzer) (Hemiptera: Aphididae), which rose from 76% in 2015 to 96% in 2016. Aphids other than M. persicae showed lower frequency of resistance. In 2015, 3% of individuals contained the resistance mutation skdr, rising to 13% in 2016 (of 45 species). Several novel resistance mutations or mutations not before reported in aphids were identified in this gene target. One of these mutations, I936V, is known to confer pyrethroid resistance in another unrelated insect, and three others occur immediately adjacent and prompt similar chemical shifts in the primary protein structure, to previously characterized mutations associated with pyrethroid resistance. Most novel mutations were found in species other than M. persicae or others currently tracked individually by the provincial aphid monitoring program, which were determined by cytochrome C oxidase I (cox1) sequencing. Through our cox1 DNA barcoding survey, at least 45 species of aphids were discovered in NB potato fields in 2015 and 2016, many of which are known carriers of PVY.

  17. Estimation of the number of aphids carrying Citrus tristeza virus that visit adult citrus trees.

    Science.gov (United States)

    Marroquín, Carlos; Olmos, Antonio; Teresa Gorris, María; Bertolini, Edson; Carmen Martínez, M; Carbonell, Emilio A; Hermoso de Mendoza, Alfonso; Cambra, Mariano

    2004-03-01

    Aphid species were counted on citrus trees in orchards in Valencia, Spain, in the spring and autumn of 1997, 1998 and 1999. Moericke yellow water traps, the 'sticky shoot' method and counts of established colonies were used in extensive surveys in which 29,502 aphids were recorded and identified. Aphis spiraecola and Aphis gossypii were the most abundant aphid species. The numbers of aphid species landing on mature trees of grapefruit, sweet orange, lemon and clementine and satsuma mandarins, were estimated by counting the numbers of young shoots/tree and aphids trapped on sticky shoots. The proportions of the different aphid species captured were: A. gossypii (53%), A. spiraecola (32%), Toxoptera aurantii (11%), Myzus persicae (1%), Aphis craccivora (1%) and other species (2%). Clementine was the most visited species with 266,700 aphids landing/tree in spring 2000, followed by lemon (147,000), sweet orange (129,150), grapefruit (103,200), and satsuma (92,400). The numbers and relative percentages of aphids carrying Citrus tristeza virus (CTV) were assessed by nested RT-PCR in single closed tubes and analysed by extraction of RNA-CTV targets from trapped aphids. An average of 37,190 CTV-carrying aphids visited each tree in spring 2000 (29 per shoot). The percentage detection of viral RNA in the aphid species that landed were 27% for A. gossypii, 23% for A. spiraecola and 19% for T. aurantii. This high incidence of aphids carrying CTV is consistent with the high prevalence and rapid spread of CTV in sweet orange, clementine, and satsuma mandarins in recent years in the region. The infection rate was proportional to the number of aphids landing/tree.

  18. The genetics of indirect ecological effects - plant parasites and aphid herbivores

    Directory of Open Access Journals (Sweden)

    Jennifer K Rowntree

    2014-04-01

    Full Text Available When parasitic plants and aphid herbivores share a host, both direct and indirect ecological effects (IEEs can influence evolutionary processes. We used a hemiparasitic plant (Rhinanthus minor, a grass host (Hordeum vulgare and a cereal aphid (Sitobion avenae to investigate the genetics of IEEs between the aphid and the parasitic plant, and looked to see how these might affect or be influenced by the genetic diversity of the host plants. Survival of R. minor depended on the parasite’s population of origin, the genotypes of the aphids sharing the host and the genetic diversity in the host plant community. Hence the indirect effects of the aphids on the parasitic plants depended on the genetic environment of the system. Here, we show that genetic variation can be important in determining the outcome of IEEs. Therefore, IEEs have the potential to influence evolutionary processes and the continuity of species interactions over time.

  19. The resistance of lettuce to the aphid Nasonovia ribisnigri

    NARCIS (Netherlands)

    Helden, van M.

    1995-01-01

    The resistance of lettuce to the aphid Nasonovia ribisnigri is based on a single, dominant gene, the Nr-gene. On the resistant plant aphids died within a few days, without any honeydew production. Transfer-experiments with a short stay on a resistant plant followed by a

  20. [An example of research on biological control: Entomophthora fungi pathogenic for aphids].

    Science.gov (United States)

    Latgé, J P; Remaudière, G; Papierok, B

    1978-01-01

    The results obtained in 15 years of research on the Entomophthorales pathogen of aphids showed the importance of the action of these fungi in the regulation of natural aphid populations and their possible use in agriculture as a biological control agent. Recent ecological studies on natural populations of aphids established the seasonal variation of the different fungal species and the diverse degrees of specificity between the species or groups of species of aphid and the various species of Entomophthora. The study of populations dynamics of an aphid species on a cultivated plant permitted the determination of the way a certain number of biotic and abiotic factors, such as temperature, humidity, thresholds of the insect population and of the infecting fungus lead to an epizootic development. If the air propagation of the disease by conidia is understood for a long time, the role of the soil as a reservoir for the infecting fungus has been demonstrated recently. Under favourable climatic conditions, the use of industrially produced resistant resting spores would allow the regulation of aphid populations in nature.

  1. Yield response of brassica varieties/strains in relation to mustard aphid lipaphis erysimi (kalt.)

    International Nuclear Information System (INIS)

    Shahzad, M.A.; Bukhari, S.A.H.; Tariq, H.

    2010-01-01

    Nine brassica varieties/advanced lines were tested to find out the varietal comparison against mustard aphid Lipaphis erysimi (kalt.) in relation to aphid population, average number of branches/plant, average number of grains per pod and grain yield (kg/ha) during 2004-2006. Minimum aphid population was observed on promising cultivar P-20 during both years 2004-2005 and 2005-06 which were 3.l and 23 aphid/30 cm of apical inflorescence from randomly selected five plants respectively. This promising strain also proved significantly the highest yielder and gave 1633 kg. grains/ha (2004-05) and 8 17.5 kg grains/ha (2005-06) followed by SP-36 which showed aphid population 36 and 32.5 aphid/30 cm inflorescence having yield 1373 and 780 kg grains/ha during the both periods respectively under report. The other parameters viz. Average number of branches per plant and average no. of grains/pod remained nonsignificant as far as aphid effect is concerned. (author)

  2. Yield response of brassica varieties/strains in relation to mustard aphid lipaphis erysimi (Kalt.)

    International Nuclear Information System (INIS)

    Shahzad, M.A.; Bukhari, S.A.H.

    2009-01-01

    Nine brassica varieties/advanced lines were tested to find out the varietal comparison against mustard aphid Lipaphis erysimi (kalt.) in relation to aphid population. average number of branches/plant, average number of grains per pod and grain yield (kg/ha) during 2004-2006. Minimum aphid population was observed on promising cultivar P-20 during both years 2004-2005-06 which were 2005-06 which were 31 and 23 aphid/30 cm of apical inflorescence from randomly selected five plants respectively. This promising strain also proved significantly the highest yielder and gave 1633 kg. grains/ha (2004,05) and 817.5 kg grains/ha (2005-06) followed by SP-36 which showed aphid population 36 and 32.5 aphid/30 cm inflorescence having yield 1373 and 780 kg grains/ha during the both periods respectively under report. The other parameters viz. Average number of branches per plant and average no. of grains/pod remained non significant as far as aphid effect is concerned. (author)

  3. Particle film affects black pecan aphid (Homoptera: Aphididae) on pecan.

    Science.gov (United States)

    Cottrell, Ted E; Wood, Bruce W; Reilly, Charles C

    2002-08-01

    Three species of aphids attack pecan foliage, Carya illinoensis (Wang.) K. Koch, and cause economic damage. We tested a kaolin-based particle film against one of these aphid species, black pecan aphid, Melanocallis caryaefoliae (Davis). Effect of particle film on host selection, adult mortality, and production of nymphs by M. caryaefoliae was tested on seedling pecans in the laboratory. Fewer M. caryaefoliae adults selected treated foliage compared with untreated foliage. A higher percentage of adults that did select treated foliage were recovered from upper leaf surfaces compared with the percentage of adults recovered from upper leaf surfaces of untreated leaves. Observations with a microscope revealed an accumulation of particle film on aphid body parts, especially on tarsi, and strongly suggests that aphid mobility was restricted. Adult mortality was higher on treated foliage and led to an overall decrease in production of nymphs on those seedlings. In addition, we measured spectral properties of treated seedling pecan foliage. Light reflectance by treated foliage was increased and absorptance decreased compared with control foliage whereas transmittance of light through control and particle film-treated leaves was similar. We did not detect any phytotoxic effect on pecan due to application of particle film.

  4. New aphid (Aphidoidea) records for the Netherlands (1984-2005)

    NARCIS (Netherlands)

    Piron, P.G.M.

    2009-01-01

    Presented are 18 species.of aphids in combination with their food-plants found in The Netherlands from 1984 to 2005 not earlier described here. Among these are well-known species that are caught with the high suction trap andlor MOERICKE yellow water traps and aphids new for The Netherlands. The

  5. Variable isotopic compositions of host plant populations preclude assessment of aphid overwintering sites

    Science.gov (United States)

    Soybean aphid (Aphis glycines Matsumura) is a pest of soybean in the northern Midwest whose migratory patterns have been difficult to quantify. Improved knowledge of soybean aphid overwintering sites could facilitate the development of control efforts with exponential impacts on aphid densities on a...

  6. Aphid secondary symbionts do not affect prey attractiveness to two species of predatory lady beetles.

    Directory of Open Access Journals (Sweden)

    Jennifer L Kovacs

    Full Text Available Heritable symbionts have been found to mediate interactions between host species and their natural enemies in a variety of organisms. Aphids, their facultative symbionts, and their potential fitness effects have been particularly well-studied. For example, the aphid facultative symbiont Regiella can protect its host from infection from a fungal pathogen, and aphids with Hamiltonella are less likely to be parasitized by parasitic wasps. Recent work has also found there to be negative fitness effects for the larvae of two species of aphidophagous lady beetles that consumed aphids with facultative symbionts. In both species, larvae that consumed aphids with secondary symbionts were significantly less likely to survive to adulthood. In this study we tested whether adult Harmonia axyridis and Hippodamia convergens lady beetles avoided aphids with symbionts in a series of choice experiments. Adults of both lady beetle species were as likely to choose aphids with symbionts as those without, despite the potential negative fitness effects associated with consuming aphids with facultative symbionts. This may suggest that under natural conditions aphid secondary symbionts are not a significant source of selection for predatory lady beetles.

  7. Survey of aphid population in a yellow passion fruit crop and its relationship on the spread Cowpea aphid-borne mosaic virus in a subtropical region of Brazil.

    Science.gov (United States)

    Garcêz, Renata Maia; Chaves, Alexandre Levi Rodrigues; Eiras, Marcelo; Meletti, Laura Maria Molina; de Azevedo Filho, Joaquim Adelino; da Silva, Leonardo Assis; Colariccio, Addolorata

    2015-01-01

    Passion fruit woodiness may be caused by Cowpea aphid-borne mosaic virus (CABMV) and is currently the major passion fruit disease in Brazil. To assess the virus-vector-host interactions, a newly introduced golden passion fruit plantation located in eastern region of São Paulo State, Brazil, was monitored. Dissemination of CABMV was determined analyzing golden passion fruit plants monthly for 18 months by PTA-ELISA. Seasonality and aphid fauna diversity was determined by identification of the captured species using yellow sticky, yellow water-pan and green tile traps. Population composition of the aphid species was determined using the descriptive index of occurrence, dominance and general classification and overlap of species in the R program. Analyses of species grouping afforded to recognize 14 aphid species. The genus Aphis represented 55.42 % of the species captured. Aphid species formed two distinct clusters, one of which was characterized by the diversity of polyphagous species that presented high potential to spread CABMV. The low abundance and diversity of aphid species did not interfere negatively in the CABMV epidemiology. The genus Aphis, particularly Aphis fabae/solanella and A. gossypii, was crucial in the spread of CABMV in passion fruit orchards in the eastern State of São Paulo.

  8. Studi tentang pola produksi alfalfa tropis (Medicago sativa L.

    Directory of Open Access Journals (Sweden)

    Rini Dwi Wahyuni

    2012-06-01

    Full Text Available Abstract The research aims to determine the growth pattern of alfalfa in the tropical region, which later can be used as a source of information for the people needed. Research methods used are experimental; the data acquired during the 90 days was showed in a graph and then analyzed using regression analysis with two variables, namely independent variables (cutting age and dependent variables (the nutritive value, height of plants, and production of dry matter (DM, organic matter (OM, and crude protein (CP. The growth pattern of alfalfa in the range 20 to 90 days was quadratic, with the equation of y= -0.0092x2 + 1.6113x – 19.257. At that range of time the alfalfa was still in vegetative growth phase. With increasing age of cutting, the alfalfa chemical compositions of DM and OM increased, but the content of CP decreased.While the production of DM, OM, and CP increased with increasing cutting age. Key words: nutrition, growth, alfalfa, tropics

  9. Reproduction and dispersal in an ant-associated root aphid community

    NARCIS (Netherlands)

    Ivens, A. B. F.; Kronauer, D. J. C.; Pen, I.; Weissing, F. J.; Boomsma, J. J.

    Clonal organisms with occasional sex are important for our general understanding of the costs and benefits that maintain sexual reproduction. Cyclically parthenogenetic aphids are highly variable in their frequency of sexual reproduction. However, studies have mostly focused on free-living aphids

  10. Inventory and assessment of foliar natural enemies of the soybean aphid (Hemiptera: Aphididae) in South Dakota.

    Science.gov (United States)

    Hesler, Louis S

    2014-06-01

    Soybean aphid (Aphis glycines Matsumura) (Hemiptera: Aphididae) is a major pest of soybean in northern production regions of North America, and insecticides have been the primary management approach while alternative methods are developed. Knowledge of arthropod natural enemies and their impact on soybean aphid is critical for developing biological control as a management tool. Soybean is a major field crop in South Dakota, but information about its natural enemies and their impact on soybean aphid is lacking. Thus, this study was conducted in field plots in eastern South Dakota during July and August of 2004 and 2005 to characterize foliar-dwelling, arthropod natural enemies of soybean aphid, and it used exclusion techniques to determine impact of natural enemies and ants (Hymenoptera: Formicidae) on soybean aphid densities. In open field plots, weekly soybean aphid densities reached a plateau of several hundred aphids per plant in 2004, and peaked at roughly 400 aphids per plant in 2005. Despite these densities, a relatively high frequency of aphid-infested plants lacked arthropod natural enemies. Lady beetles (Coleoptera: Coccinellidae) were most abundant, peaking at 90 and 52% of all natural enemies sampled in respective years, and Harmonia axyridis Pallas was the most abundant lady beetle. Green lacewings (Neuroptera: Chrysopidae) were abundant in 2005, due mainly to large numbers of their eggs. Abundances of arachnids and coccinellid larvae correlated with soybean aphid densities each year, and chrysopid egg abundance was correlated with aphid density in 2005. Three-week cage treatments of artificially infested soybean plants in 2004 showed that noncaged plants had fewer soybean aphids than caged plants, but abundance of soybean aphid did not differ among open cages and ones that provided partial or total exclusion of natural enemies. In 2005, plants within open cages had fewer soybean aphids than those within cages that excluded natural enemies, and aphid

  11. The Green Lacewing, Chrysoperla carnea: Preference between Lettuce Aphids, Nasonovia ribisnigri, and Western Flower Thrips, Frankliniella occidentalis

    OpenAIRE

    Shrestha, Govinda; Enkegaard, Annie

    2013-01-01

    This study investigated the prey preference of 3rd instar green lacewing, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), between western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and lettuce aphids, Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae) in laboratory experiments at 25 ? 1? C and 70 ? 5% RH with five prey ratios (10 aphids:80 thrips, 25 aphids:65 thrips, 45 aphids:45 thrips, 65 aphids:25 thrips, and 80 aphids:10 thrips). Third instar...

  12. Orally Delivered Scorpion Antimicrobial Peptides Exhibit Activity against Pea Aphid (Acyrthosiphon pisum) and Its Bacterial Symbionts.

    Science.gov (United States)

    Luna-Ramirez, Karen; Skaljac, Marisa; Grotmann, Jens; Kirfel, Phillipp; Vilcinskas, Andreas

    2017-08-24

    Aphids are severe agricultural pests that damage crops by feeding on phloem sap and vectoring plant pathogens. Chemical insecticides provide an important aphid control strategy, but alternative and sustainable control measures are required to avoid rapidly emerging resistance, environmental contamination, and the risk to humans and beneficial organisms. Aphids are dependent on bacterial symbionts, which enable them to survive on phloem sap lacking essential nutrients, as well as conferring environmental stress tolerance and resistance to parasites. The evolution of aphids has been accompanied by the loss of many immunity-related genes, such as those encoding antibacterial peptides, which are prevalent in other insects, probably because any harm to the bacterial symbionts would inevitably affect the aphids themselves. This suggests that antimicrobial peptides (AMPs) could replace or at least complement conventional insecticides for aphid control. We fed the pea aphids ( Acyrthosiphon pisum ) with AMPs from the venom glands of scorpions. The AMPs reduced aphid survival, delayed their reproduction, displayed in vitro activity against aphid bacterial symbionts, and reduced the number of symbionts in vivo. Remarkably, we found that some of the scorpion AMPs compromised the aphid bacteriome, a specialized organ that harbours bacterial symbionts. Our data suggest that scorpion AMPs holds the potential to be developed as bio-insecticides, and are promising candidates for the engineering of aphid-resistant crops.

  13. Orally Delivered Scorpion Antimicrobial Peptides Exhibit Activity against Pea Aphid (Acyrthosiphon pisum and Its Bacterial Symbionts

    Directory of Open Access Journals (Sweden)

    Karen Luna-Ramirez

    2017-08-01

    Full Text Available Aphids are severe agricultural pests that damage crops by feeding on phloem sap and vectoring plant pathogens. Chemical insecticides provide an important aphid control strategy, but alternative and sustainable control measures are required to avoid rapidly emerging resistance, environmental contamination, and the risk to humans and beneficial organisms. Aphids are dependent on bacterial symbionts, which enable them to survive on phloem sap lacking essential nutrients, as well as conferring environmental stress tolerance and resistance to parasites. The evolution of aphids has been accompanied by the loss of many immunity-related genes, such as those encoding antibacterial peptides, which are prevalent in other insects, probably because any harm to the bacterial symbionts would inevitably affect the aphids themselves. This suggests that antimicrobial peptides (AMPs could replace or at least complement conventional insecticides for aphid control. We fed the pea aphids (Acyrthosiphon pisum with AMPs from the venom glands of scorpions. The AMPs reduced aphid survival, delayed their reproduction, displayed in vitro activity against aphid bacterial symbionts, and reduced the number of symbionts in vivo. Remarkably, we found that some of the scorpion AMPs compromised the aphid bacteriome, a specialized organ that harbours bacterial symbionts. Our data suggest that scorpion AMPs holds the potential to be developed as bio-insecticides, and are promising candidates for the engineering of aphid-resistant crops.

  14. High-throughput phenotyping of plant resistance to aphids by automated video tracking.

    Science.gov (United States)

    Kloth, Karen J; Ten Broeke, Cindy Jm; Thoen, Manus Pm; Hanhart-van den Brink, Marianne; Wiegers, Gerrie L; Krips, Olga E; Noldus, Lucas Pjj; Dicke, Marcel; Jongsma, Maarten A

    2015-01-01

    Piercing-sucking insects are major vectors of plant viruses causing significant yield losses in crops. Functional genomics of plant resistance to these insects would greatly benefit from the availability of high-throughput, quantitative phenotyping methods. We have developed an automated video tracking platform that quantifies aphid feeding behaviour on leaf discs to assess the level of plant resistance. Through the analysis of aphid movement, the start and duration of plant penetrations by aphids were estimated. As a case study, video tracking confirmed the near-complete resistance of lettuce cultivar 'Corbana' against Nasonovia ribisnigri (Mosely), biotype Nr:0, and revealed quantitative resistance in Arabidopsis accession Co-2 against Myzus persicae (Sulzer). The video tracking platform was benchmarked against Electrical Penetration Graph (EPG) recordings and aphid population development assays. The use of leaf discs instead of intact plants reduced the intensity of the resistance effect in video tracking, but sufficiently replicated experiments resulted in similar conclusions as EPG recordings and aphid population assays. One video tracking platform could screen 100 samples in parallel. Automated video tracking can be used to screen large plant populations for resistance to aphids and other piercing-sucking insects.

  15. The green lacewing, Chrysoperla carnea: preference between lettuce aphids, Nasonovia ribisnigri, and Western flower thrips, Frankliniella occidentalis.

    Science.gov (United States)

    Shrestha, Govinda; Enkegaard, Annie

    2013-01-01

    This study investigated the prey preference of 3(rd) instar green lacewing, Chrysoperla carnea Stephens (Neuroptera: Chrysopidae), between western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae), and lettuce aphids, Nasonovia ribisnigri (Mosley) (Hemiptera: Aphididae) in laboratory experiments at 25 ± 1° C and 70 ± 5% RH with five prey ratios (10 aphids:80 thrips, 25 aphids:65 thrips, 45 aphids:45 thrips, 65 aphids:25 thrips, and 80 aphids:10 thrips). Third instar C. carnea larvae readily preyed upon both thrips and aphids, with thrips mortality varying between 40 and 90%, and aphid mortality between 52 and 98%. Chrysoperla carnea had a significant preference for N. ribisnigri at two ratios (10 aphids:80 thrips, 65 aphids:25 thrips), but no preference for either prey at the other ratios. There was no significant linear relationship between preference index and prey ratio, but a significant intercept of the linear regression indicated an overall preference of C. carnea for aphids with a value of 0.651 ± 0.054. The possible implications of these findings for control of N. ribisnigri and F. occidentalis by C. carnea are discussed.

  16. Occurrence of Transgenic Feral Alfalfa (Medicago sativa subsp. sativa L.) in Alfalfa Seed Production Areas in the United States.

    Science.gov (United States)

    Greene, Stephanie L; Kesoju, Sandya R; Martin, Ruth C; Kramer, Matthew

    2015-01-01

    The potential environmental risks of transgene exposure are not clear for alfalfa (Medicago sativa subsp. sativa), a perennial crop that is cross-pollinated by insects. We gathered data on feral alfalfa in major alfalfa seed-production areas in the western United States to (1) evaluate evidence that feral transgenic plants spread transgenes and (2) determine environmental and agricultural production factors influencing the location of feral alfalfa, especially transgenic plants. Road verges in Fresno, California; Canyon, Idaho; and Walla Walla, Washington were surveyed in 2011 and 2012 for feral plants, and samples were tested for the CP4 EPSPS protein that conveys resistance to glyphosate. Of 4580 sites surveyed, feral plants were observed at 404 sites. Twenty-seven percent of these sites had transgenic plants. The frequency of sites having transgenic feral plants varied among our study areas. Transgenic plants were found in 32.7%, 21.4.7% and 8.3% of feral plant sites in Fresno, Canyon and Walla Walla, respectively. Spatial analysis suggested that feral populations started independently and tended to cluster in seed and hay production areas, places where seed tended to drop. Significant but low spatial auto correlation suggested that in some instances, plants colonized nearby locations. Neighboring feral plants were frequently within pollinator foraging range; however, further research is needed to confirm transgene flow. Locations of feral plant clusters were not well predicted by environmental and production variables. However, the likelihood of seed spillage during production and transport had predictive value in explaining the occurrence of transgenic feral populations. Our study confirms that genetically engineered alfalfa has dispersed into the environment, and suggests that minimizing seed spillage and eradicating feral alfalfa along road sides would be effective strategies to minimize transgene dispersal.

  17. Parasitization of commercially available parasitoid species against the lettuce aphid, Nasonovia ribisnigri (Hemiptera: Aphididae).

    Science.gov (United States)

    Shrestha, G; Skovgård, H; Enkegaard, A

    2014-12-01

    The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. Little documentation exists for the control efficacy of aphid parasitoids against N. ribisnigri. This laboratory study evaluated three commercially available parasitoid species: Aphidius colemani (Viereck), Lysiphlebus testaceipes (Cresson), and Aphelinus abdominalis (Dalman) for their mortality impact on N. ribisnigri. The green peach aphid Myzus persicae (Sulzer) was included as a reference aphid. The study showed that A. abdominalis successfully parasitized 39 and 13% of the offered N. ribisnigri and M. persicae, respectively, within a 24-h exposure period. In contrast, none of the lettuce aphids exposed to Ap. colemani or L. testaceipes were successfully parasitized, whereas 60 and 3.5% of M. persicae, respectively, were successfully parasitized within a 6-h exposure period. Lettuce aphid mortality due to incomplete parasitization was 26 and 31% when exposed to Ap. colemani and L. testaceipes, respectively, with corresponding values for M. persicae being 5 and 10%, respectively. Mortality as a result of incomplete parasitization when aphids were exposed to A. abdominalis was low for both aphid species. The total mortality inflicted by A. abdominalis within a 24-h exposure period was 51% for the lettuce aphids and significantly less (19%) for green peach aphids. In contrast, Ap. colemani inflicted a higher mortality in M. persicae (65%) compared with N. ribisnigri (26%) within a 6-h exposure period. L. testaceipes caused a greater mortality in N. ribisnigri as compared with M. persicae. This study concludes that A. abdominalis has the potential to be used against N. ribisnigri in inoculative biocontrol programs as compared with the other parasitoid species based on successful parasitization.

  18. Variable Isotopic Compositions of Host Plant Populations Preclude Assessment of Aphid Overwintering Sites

    Directory of Open Access Journals (Sweden)

    Michael S. Crossley

    2017-12-01

    Full Text Available Soybean aphid (Aphis glycines Matsumura is a pest of soybean in the northern Midwest whose migratory patterns have been difficult to quantify. Improved knowledge of soybean aphid overwintering sites could facilitate the development of control efforts with exponential impacts on aphid densities on a regional scale. In this preliminary study, we explored the utility of variation in stable isotopes of carbon and nitrogen to distinguish soybean aphid overwintering origins. We compared variation in bulk 13C and 15N content in buckthorn (Rhamnus cathartica L. and soybean aphids in Wisconsin, among known overwintering locations in the northern Midwest. Specifically, we looked for associations between buckthorn and environmental variables that could aid in identifying overwintering habitats. We detected significant evidence of correlation between the bulk 13C and 15N signals of soybean aphids and buckthorn, despite high variability in stable isotope composition within and among buckthorn plants. Further, the 15N signal in buckthorn varied predictably with soil composition. However, lack of sufficient differentiation of geographic areas along axes of isotopic and environmental variation appears to preclude the use of carbon and nitrogen isotopic signals as effective predictors of likely aphid overwintering sites. These preliminary data suggest the need for future work that can further account for variability in 13C and 15N within/among buckthorn plants, and that explores the utility of other stable isotopes in assessing likely aphid overwintering sites.

  19. Trichoderma harzianum enhances tomato indirect defense against aphids.

    Science.gov (United States)

    Coppola, Mariangela; Cascone, Pasquale; Chiusano, Maria Luisa; Colantuono, Chiara; Lorito, Matteo; Pennacchio, Francesco; Rao, Rosa; Woo, Sheridan Lois; Guerrieri, Emilio; Digilio, Maria Cristina

    2017-12-01

    Many fungal root symbionts of the genus Trichoderma are well-known for their beneficial effects on agronomic performance and protection against plant pathogens; moreover, they may enhance protection from insect pests, by triggering plant resistance mechanisms. Defense barriers against insects are induced by the activation of metabolic pathways involved in the production of defense-related plant compounds, either directly active against herbivore insects, or exerting an indirect effect, by increasing the attraction of herbivore natural enemies. In a model system composed of the tomato plant, the aphid Macrosiphum euphorbiae and the parasitoid Aphidius ervi, plant metabolic changes induced by Trichoderma harzianum and their effects on higher trophic levels have been assessed. T. harzianum T22 treatments induce a primed state that upon aphid attacks leads to an increased attraction of aphid parasitoids, mediated by the enhanced production of volatile organic compounds (VOCs) that are known to induce Aphidius ervi flight. Transcriptome sequencing of T22-treated plants infested by aphids showed a remarkable upregulation of genes involved in terpenoids biosynthesis and salicylic acid pathway, which are consistent with the observed flight response of A. ervi and the VOC bouquet profile underlying this behavioral response. © 2017 Institute of Zoology, Chinese Academy of Sciences.

  20. Indirect effect of a transgenic wheat on aphids through enhanced powdery mildew resistance.

    Directory of Open Access Journals (Sweden)

    Simone von Burg

    Full Text Available In agricultural ecosystems, arthropod herbivores and fungal pathogens are likely to colonise the same plant and may therefore affect each other directly or indirectly. The fungus that causes powdery mildew (Blumeria graminis tritici and cereal aphids are important pests of wheat but interactions between them have seldom been investigated. We studied the effects of powdery mildew of wheat on two cereal aphid species, Metopolophium dirhodum and Rhopalosiphum padi. We hypothesized that aphid number and size will be smaller on powdery mildew-infected plants than on non-infected plants. In a first experiment we used six commercially available wheat varieties whereas in the second experiment we used a genetically modified (GM mildew-resistant wheat line and its non-transgenic sister line. Because the two lines differed only in the presence of the transgene and in powdery mildew resistance, experiment 2 avoided the confounding effect of variety. In both experiments, the number of M. dirhodum but not of R. padi was reduced by powdery mildew infection. Transgenic mildew-resistant lines therefore harboured bigger aphid populations than the non-transgenic lines. For both aphid species individual size was mostly influenced by aphid number. Our results indicate that plants that are protected from a particular pest (powdery mildew became more favourable for another pest (aphids.

  1. Redox Control of Aphid Resistance through Altered Cell Wall Composition and Nutritional Quality.

    Science.gov (United States)

    Rasool, Brwa; McGowan, Jack; Pastok, Daria; Marcus, Sue E; Morris, Jenny A; Verrall, Susan R; Hedley, Peter E; Hancock, Robert D; Foyer, Christine H

    2017-09-01

    The mechanisms underpinning plant perception of phloem-feeding insects, particularly aphids, remain poorly characterized. Therefore, the role of apoplastic redox state in controlling aphid infestation was explored using transgenic tobacco ( Nicotiana tabacum ) plants that have either high (PAO) or low (TAO) ascorbate oxidase (AO) activities relative to the wild type. Only a small number of leaf transcripts and metabolites were changed in response to genotype, and cell wall composition was largely unaffected. Aphid fecundity was decreased significantly in TAO plants compared with other lines. Leaf sugar levels were increased and maximum extractable AO activities were decreased in response to aphids in all genotypes. Transcripts encoding the Respiratory Burst Oxidase Homolog F, signaling components involved in ethylene and other hormone-mediated pathways, photosynthetic electron transport components, sugar, amino acid, and cell wall metabolism, were increased significantly in the TAO plants in response to aphid perception relative to other lines. The levels of galactosylated xyloglucan were decreased significantly in response to aphid feeding in all the lines, the effect being the least in the TAO plants. Similarly, all lines exhibited increases in tightly bound (1→4)-β-galactan. Taken together, these findings identify AO-dependent mechanisms that limit aphid infestation. © 2017 American Society of Plant Biologists. All Rights Reserved.

  2. Indirect effect of a transgenic wheat on aphids through enhanced powdery mildew resistance.

    Science.gov (United States)

    von Burg, Simone; Álvarez-Alfageme, Fernando; Romeis, Jörg

    2012-01-01

    In agricultural ecosystems, arthropod herbivores and fungal pathogens are likely to colonise the same plant and may therefore affect each other directly or indirectly. The fungus that causes powdery mildew (Blumeria graminis tritici) and cereal aphids are important pests of wheat but interactions between them have seldom been investigated. We studied the effects of powdery mildew of wheat on two cereal aphid species, Metopolophium dirhodum and Rhopalosiphum padi. We hypothesized that aphid number and size will be smaller on powdery mildew-infected plants than on non-infected plants. In a first experiment we used six commercially available wheat varieties whereas in the second experiment we used a genetically modified (GM) mildew-resistant wheat line and its non-transgenic sister line. Because the two lines differed only in the presence of the transgene and in powdery mildew resistance, experiment 2 avoided the confounding effect of variety. In both experiments, the number of M. dirhodum but not of R. padi was reduced by powdery mildew infection. Transgenic mildew-resistant lines therefore harboured bigger aphid populations than the non-transgenic lines. For both aphid species individual size was mostly influenced by aphid number. Our results indicate that plants that are protected from a particular pest (powdery mildew) became more favourable for another pest (aphids).

  3. Sugarcane Aphid in Sorghum

    Science.gov (United States)

    Evers, Logan

    2018-01-01

    This article is intended for readers in the production agriculture industry who deal with grain sorghum throughout the growing season. This publication will discuss the impacts of the sugarcane aphid in various crops and the ways to manage and identify them as they continue to advance north.

  4. First survey on ecological host range of aphid pathogenic fungi (Phylum Entomophthoromycota) in Tunisia

    DEFF Research Database (Denmark)

    Ben Fekih, Ibtissem; Boukhris-Bouhachem, Sonia; Allagui, Mohamed Bechir

    2015-01-01

    Summary. The natural occurrence of fungal pathogens of aphids and their ecological host range was investigated in Tunisia from 2009 to 2012. The survey focused on aphid infesting different crops and weeds and included 10 different aphid species. Samples were collected from eight agricultural crops...... (Entomophthorales: Ancylistaceae) and Neozygites fresenii (Neozygitales: Neozygitaceae). The occurrence of entomophthoralean fungi depended on the sampling area, the bioclimatic zone, and aphid species. P. neoaphidis and E. planchoniana were the predominant pathogens infecting a wide range of aphid species whereas...... sites belonging to three different bioclimatic zones. Four pathogens from the phylum Entomophthoromycota were found to occur naturally in Tunisian ecosystems: Pandora neoaphidis (Entomophthorales: Entomophthoraceae), Entomophthora planchoniana (Entomophthorales: Entomophthoraceae), Conidiobolus obscurus...

  5. Efficiency of alfalfa seed processing with different seed purity

    OpenAIRE

    Đokić, Dragoslav; Stanisavljević, Rade; Terzić, Dragan; Milenković, Jasmina; Radivojević, Gordana; Koprivica, Ranko; Štrbanović, Ratibor

    2015-01-01

    The work was carried out analysis of the impact of the initial purity of raw alfalfa seed on the resulting amount of processed seed in the processing. Alfalfa is very important perennial forage legume which is used for fodder and seed production. Alfalfa seed is possible to achieve high yields and very good financial effects. To obtain the seed material with good characteristics complex machines for cleaning and sorting seeds are used. In the processing center of the Institute for forage crop...

  6. Application of plant growth regulators mitigates chlorotic foliar injury by the black pecan aphid (Hemiptera: Aphididae).

    Science.gov (United States)

    Cottrell, Ted E; Wood, Bruce W; Ni, Xinzhi

    2010-11-01

    Black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), feeding elicits localized chlorotic injury to pecan foliage [Carya illinoinensis (Wangenh.) K Koch] and apparent acceleration of leaf senescence and defoliation. The ability of certain plant growth regulators (PGRs) (forchlorfenuron, gibberellic acid and aviglycine) to prevent M. caryaefoliae from triggering pecan leaf chlorosis and senescence-like processes was evaluated on two dates in both 2006 and 2007. Treatments were applied to orchard foliage and used in laboratory leaf-disc bioassays to assess possible reduction in aphid-elicited chlorosis and concomitant effects on aphid mortality and development. Foliage pretreated with forchlorfenuron + gibberellic acid prior to being challenged with aphids resulted in significantly less aphid-elicited chlorosis than did control or aviglycine-treated leaf discs. No PGR affected aphid mortality; however, development time was increased by forchlorfenuron + gibberellic acid in 2006 and by aviglycine + gibberellic acid on one date in 2007. Certain PGRs possess the potential for usage on pecan to protect foliar canopies from M. caryaefoliae via changes in the susceptibility of the host leaf to senescence-like factors being introduced by feeding aphids. This protective effect on host foliage and the associated suppressive effect on development of feeding aphids might also be relevant to pest management programs on other aphid-crop systems in which aphid-elicited chlorosis and senescence-like processes can limit profitability. Published 2010 by John Wiley & Sons, Ltd.

  7. Allelopathic interference of alfalfa (Medicago sativa L.) genotypes to annual ryegrass (Lolium rigidum).

    Science.gov (United States)

    Zubair, Hasan Muhammad; Pratley, James E; Sandral, G A; Humphries, A

    2017-07-01

    Alfalfa (Medicago sativa L.) genotypes at varying densities were investigated for allelopathic impact using annual ryegrass (Lolium rigidum) as the target species in a laboratory bioassay. Three densities (15, 30, and 50 seedlings/beaker) and 40 alfalfa genotypes were evaluated by the equal compartment agar method (ECAM). Alfalfa genotypes displayed a range of allelopathic interference in ryegrass seedlings, reducing root length from 5 to 65%. The growth of ryegrass decreased in response to increasing density of alfalfa seedlings. At the lowest density, Q75 and Titan9 were the least allelopathic genotypes. An overall inhibition index was calculated to rank each alfalfa genotype. Reduction in seed germination of annual ryegrass occurred in the presence of several alfalfa genotypes including Force 10, Haymaster7 and SARDI Five. A comprehensive metabolomic analysis using Quadruple Time of Flight (Q-TOF), was conducted to compare six alfalfa genotypes. Variation in chemical compounds was found between alfalfa root extracts and exudates and also between genotypes. Further individual compound assessments and quantitative study at greater chemical concentrations are needed to clarify the allelopathic activity. Considerable genetic variation exists among alfalfa genotypes for allelopathic activity creating the opportunity for its use in weed suppression through selection.

  8. Expression of Pinellia pedatisecta Lectin Gene in Transgenic Wheat Enhances Resistance to Wheat Aphids

    Directory of Open Access Journals (Sweden)

    Xiaoliang Duan

    2018-03-01

    Full Text Available Wheat aphids are major pests during the seed filling stage of wheat. Plant lectins are toxic to sap-sucking pests such as wheat aphids. In this study, Pinellia pedatisecta agglutinin (ppa, a gene encoding mannose binding lectin, was cloned, and it shared 92.69% nucleotide similarity and 94% amino acid similarity with Pinellia ternata agglutinin (pta. The ppa gene, driven by the constitutive and phloem-specific ribulose bisphosphate carboxylase small subunit gene (rbcs promoter in pBAC-rbcs-ppa expression vector, was transferred into the wheat cultivar Baofeng104 (BF104 by particle bombardment transformation. Fifty-four T0 transgenic plants were generated. The inheritance and expression of the ppa gene were confirmed by PCR and RT-PCR analysis respectively, and seven homozygous transgenic lines were obtained. An aphid bioassay on detached leaf segments revealed that seven ppa transgenic wheat lines had lower aphid growth rates and higher inhibition rates than BF104. Furthermore, two-year aphid bioassays in isolated fields showed that aphid numbers per tiller of transgenic lines were significantly decreased, compared with wild type BF104. Therefore, ppa could be a strong biotechnological candidate to produce aphid-resistant wheat.

  9. Arabidopsis thaliana - Myzus persicae interaction: shaping the understanding of plant defense against phloem-feeding aphids

    Directory of Open Access Journals (Sweden)

    Joe eLouis

    2013-07-01

    Full Text Available The phloem provides a unique niche for several organisms. Aphids are a large group of Hemipteran insects that utilize stylets present in their mouthparts to pierce sieve elements and drink large volumes of phloem sap. In addition, many aphids also vector viral diseases. Myzus persicae, commonly known as the green peach aphid (GPA, is an important pest of a large variety of plants that includes Arabidopsis thaliana. This review summarizes recent studies that have exploited the compatible interaction between Arabidopsis and GPA to understand the molecular and physiological mechanisms utilized by plants to control aphid infestation, as well as genes and mechanisms that contribute to susceptibility. In addition, recent efforts to identify aphid-delivered elicitors of plant defenses and novel aphid salivary components that facilitate infestation are also discussed.

  10. Effects of alfalfa meal on carcase quality and fat metabolism of Muscovy ducks.

    Science.gov (United States)

    Jiang, J F; Song, X M; Huang, X; Wu, J L; Zhou, W D; Zheng, H C; Jiang, Y Q

    2012-01-01

    1. The effects of alfalfa meal on carcase quality and fat metabolism of Muscovy duck were evaluated. The objective of this research was to establish whether alfalfa meal can reduce fat content and improve carcase quality of Muscovy duck. Animal products with a high fat content present a risk factor for many diseases. Reducing fat content in poultry products is an important goal for the poultry industry. 2. A total of 240 14-d-old white Muscovy ducks were selected and randomly allocated to 1 of 4 dietary treatments containing 0, 3, 6, and 9% of alfalfa meal for 5 weeks. Growth performances were recorded and carcase characteristics and lipid parameters were analysed. 3. Results showed that 3, 6, and 9% alfalfa meal in diet had no significant effects on growth performance of Muscovy ducks from 14 to 49 d of age. Ducks given 3, 6, and 9% alfalfa meal had significantly higher dressing percentage and lower abdominal fat percentage compared with those given no alfalfa meal. Ducks given 9% alfalfa meal had higher breast meat percentage compared with those given no alfalfa meal. The concentrations of triglyceride, total cholesterol, low density lipoprotein (LDL), very low density lipoprotein (VLDL) and free fatty acid in serum of ducks fed on alfalfa meal decreased. Alfalfa meal in the diet decreased abdominal fat percentage and improved carcase traits of Muscovy duck. 4. The study showed that dietary alfalfa meal decreased abdominal fat percentage and improved carcase traits, without an adverse effect on performance.

  11. Quantitative Simulation of Damage Roots on Inoculated Alfalfa by Arbuscular Mycorrhiza Fungi

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    Ying Liu

    2017-12-01

    Full Text Available Underground mining would cause ground subsidence damage and large amounts of cracks, which would result a loss of surface moisture and nutrient and intensifying drought. There are a few reports about damage to plant roots caused by coal mining. The irregular distribution of plant roots in soil and the different forces generated in process of surface subsidence are difficult to study comprehensively. The technologies to repair damaged plant roots have not been completely perfected yet. Based on quantitative simulation of alfalfa root cut-repair experiment, this paper discusses the influences of inoculated Arbuscular Mycorrhiza Fungi on alfalfa root and the mitigation effects of an inoculation on the growth of alfalfa. Root injured alfalfa were investigated by soil pot experiments. The result indicated that at the same cut degree, the growth situation of inoculated alfalfa is better than the contrast. Compared with the Olsen-P content, at cut level of 0 and 1/3, the sand of inoculated alfalfa has less Olsen-P than contrast, at cut degree of 1/2 and 2/3, the sand of inoculated alfalfa has more Olsen-P than contrast, at degree of 3/4, the sand of inoculated alfalfa has less Olsen-P than contrast, the change trend of Olsen-P content is concerned with the relative strength size of absorb Olsen-P by alfalfa root and dissolve Olsen-P by root exudates and hyphae interstate.

  12. Preparing soft-bodied arthropods for microscope examination: Aphids (Insecta: Hemiptera: Aphididae)

    Science.gov (United States)

    Proper identification of aphids (Hemiptera: Aphididae) require preparation of the specimen on a microscope slide. This training video provides visual instruction on how to prepare aphid specimens on microscope slides for examination and indentification. Steps ranging from collection, specimen clear...

  13. Removal of phenanthrene in contaminated soil by combination of alfalfa, white-rot fungus, and earthworms.

    Science.gov (United States)

    Deng, Shuguang; Zeng, Defang

    2017-03-01

    The aim of this study was to investigate the removal of phenanthrene by combination of alfalfa, white-rot fungus, and earthworms in soil. A 60-day experiment was conducted. Inoculation with earthworms and/or white-rot fungus increased alfalfa biomass and phenanthrene accumulation in alfalfa. However, inoculations of alfalfa and white-rot fungus can significantly decrease the accumulation of phenanthrene in earthworms. The removal rates for phenanthrene in soil were 33, 48, 66, 74, 85, and 93% under treatments control, only earthworms, only alfalfa, earthworms + alfalfa, alfalfa + white-rot fungus, and alfalfa + earthworms + white-rot fungus, respectively. The present study demonstrated that the combination of alfalfa, earthworms, and white-rot fungus is an effective way to remove phenanthrene in the soil. The removal is mainly via stimulating both microbial development and soil enzyme activity.

  14. NUTRITIONAL ENHANCEMENT OF ALFALFA THROUGH GENETIC ENGINEERING

    Directory of Open Access Journals (Sweden)

    J. Faragó

    2008-09-01

    Full Text Available Alfalfa (Medicago sativa L. is a pasture legume crop of primary importance to animal production throughout the world. The nutritional quality of alfalfa, as of other leguminous forage crops, is mainly determined by their content in selected essential amino acids (EAAs, such as methionine (Met and cysteine (Cys. In alfalfa, however, these S-containing amino acids constitute only about 1% or less of crude proteins (Frame et al., 1998. This is significantly less than the 3.5% Met+Cys content in the recommended FAO reference protein (FAO, 1973. Recent advances in genetic engineering allow to use the transgenic approach to increase the content of specific essential amino acids in target plant species. A number of different molecular approaches have been developed to address this issue, such as over-expression of a heterologous or homologous Met-rich protein, expression of a synthetic protein, modification of protein sequence, and metabolic engineering of the free amino acid pool and protein sink. To study the possibility of transgenic enhancement of nutritional quality of alfalfa, we used the approach of expression of a heterologous protein rich in Met+Cys in cells of alfalfa. The T-DNA introduced into the genome of alfalfa, using Agrobacterium tumefaciens-mediated genetic transformation, contained the selectable merker gene nptII for kanamycin (Kn resistance, and a cDNA of Ov gene from Japanese quail (Coturnix coturnix coding for a high Met+Cys containing ovalbumine (Mucha et al., 1991, both under constitutive promoters. After cocultivation of petiole segment- and leaf blade-explants of two highly embryogenic alfalfa genotypes Rg9/I-14-22 and Rg11/I-10-68 (Faragó et al., 1997 with cells of A. tumefaciens strain AGL1 carrying the nptII and Ov genes, and selection of transgenic cells on Kn containing selective media, more than one hundred putatively transgenic regenerants were obtained through somatic embryogenesis. Biological (Kn rooting assay

  15. Spectral Detection of Soybean Aphid (Hemiptera: Aphididae) and Confounding Insecticide Effects in Soybean

    Science.gov (United States)

    Alves, Tavvs Micael

    Soybean aphid, Aphis glycines (Hemiptera: Aphididae) is the primary insect pest of soybean in the northcentral United States. Soybean aphid may cause stunted plants, leaf discoloration, plant death, and decrease soybean yield by 40%. Sampling plans have been developed for supporting soybean aphid management. However, growers' perception about time involved in direct insect counts has been contributing to a lower adoption of traditional pest scouting methods and may be associated with the use of prophylactic insecticide applications in soybean. Remote sensing of plant spectral (light-derived) responses to soybean aphid feeding is a promising alternative to estimate injury without direct insect counts and, thus, increase adoption and efficiency of scouting programs. This research explored the use of remote sensing of soybean reflectance for detection of soybean aphids and showed that foliar insecticides may have implications for subsequent use of soybean spectral reflectance for pest detection. (Abstract shortened by ProQuest.).

  16. The Use of Gene Modification and Advanced Molecular Structure Analyses towards Improving Alfalfa Forage.

    Science.gov (United States)

    Lei, Yaogeng; Hannoufa, Abdelali; Yu, Peiqiang

    2017-01-29

    Alfalfa is one of the most important legume forage crops in the world. In spite of its agronomic and nutritive advantages, alfalfa has some limitations in the usage of pasture forage and hay supplement. High rapid degradation of protein in alfalfa poses a risk of rumen bloat to ruminants which could cause huge economic losses for farmers. Coupled with the relatively high lignin content, which impedes the degradation of carbohydrate in rumen, alfalfa has unbalanced and asynchronous degradation ratio of nitrogen to carbohydrate (N/CHO) in rumen. Genetic engineering approaches have been used to manipulate the expression of genes involved in important metabolic pathways for the purpose of improving the nutritive value, forage yield, and the ability to resist abiotic stress. Such gene modification could bring molecular structural changes in alfalfa that are detectable by advanced structural analytical techniques. These structural analyses have been employed in assessing alfalfa forage characteristics, allowing for rapid, convenient and cost-effective analysis of alfalfa forage quality. In this article, we review two major obstacles facing alfalfa utilization, namely poor protein utilization and relatively high lignin content, and highlight genetic studies that were performed to overcome these drawbacks, as well as to introduce other improvements to alfalfa quality. We also review the use of advanced molecular structural analysis in the assessment of alfalfa forage for its potential usage in quality selection in alfalfa breeding.

  17. The Use of Gene Modification and Advanced Molecular Structure Analyses towards Improving Alfalfa Forage

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Yaogeng; Hannoufa, Abdelali; Yu, Peiqiang

    2017-01-29

    Alfalfa is one of the most important legume forage crops in the world. In spite of its agronomic and nutritive advantages, alfalfa has some limitations in the usage of pasture forage and hay supplement. High rapid degradation of protein in alfalfa poses a risk of rumen bloat to ruminants which could cause huge economic losses for farmers. Coupled with the relatively high lignin content, which impedes the degradation of carbohydrate in rumen, alfalfa has unbalanced and asynchronous degradation ratio of nitrogen to carbohydrate (N/CHO) in rumen. Genetic engineering approaches have been used to manipulate the expression of genes involved in important metabolic pathways for the purpose of improving the nutritive value, forage yield, and the ability to resist abiotic stress. Such gene modification could bring molecular structural changes in alfalfa that are detectable by advanced structural analytical techniques. These structural analyses have been employed in assessing alfalfa forage characteristics, allowing for rapid, convenient and cost-effective analysis of alfalfa forage quality. In this article, we review two major obstacles facing alfalfa utilization, namely poor protein utilization and relatively high lignin content, and highlight genetic studies that were performed to overcome these drawbacks, as well as to introduce other improvements to alfalfa quality. We also review the use of advanced molecular structural analysis in the assessment of alfalfa forage for its potential usage in quality selection in alfalfa breeding.

  18. [Population dynamics of ground carabid beetles and spiders in a wheat field along the wheat-alfalfa interface and their response to alfalfa mowing].

    Science.gov (United States)

    Liu, Wen-Hui; Hu, Yi-Jun; Hu, Wen-Chao; Hong, Bo; Guan, Xiao-Qing; Ma, Shi-Yu; He, Da-Han

    2014-09-01

    Taking the wheat-alfalfa and wheat-wheat interfaces as model systems, sampling points were set by the method of pitfall trapping in the wheat field at the distances of 3 m, 6 m, 9 m, 12 m, 15 m, 18 m, 21 m, 24 m, and 27 m from the interface. The species composition and abundance of ground carabid beetles and spiders captured in pitfalls were investigated. The results showed that, to some extent there was an edge effect on species diversity and abundance of ground carabid beetles and spiders along the two interfaces. A marked edge effect was observed between 15 m and 18 m along the alfalfa-wheat interface, while no edge effect was found at a distance over 20 m. The edge effect along the wheat-wheat interface was weaker in comparison to the alfalfa-wheat interface. Alfalfa mowing resulted in the migration of a large number of ground carabid beetles and spiders to the adjacent wheat filed. During ten days since mowing, both species and abundance of ground carabid beetles and spiders increased in wheat filed within the distance of 20 m along the alfalfa-wheat interface. The spatial distribution of species diversity of ground beetles and spiders, together with the population abundance of the dominant Chlaenius pallipes and Pardosa astrigera, were depicted, which could directly indicate the migrating process of natural enemy from alfalfa to wheat field.

  19. Aphids of the genus Diuraphis caught by Johnson suction trap in Poznań, Poland

    Directory of Open Access Journals (Sweden)

    Strażyński Przemysław

    2016-12-01

    Full Text Available In 1973-2011 in Poznań, aphid catches were carried out using Johnson’s suction trap. Since then the suction trap located at the Institute of Plant Protection - National Research Institute in Poznań has continuously recorded the daily and seasonal dynamics of aphid flights. The collected results has been used to establish one of the largest databases of this type in Europe. The data also allow tracking changes in aphid biodiversity under the changing climatic conditions. Three aphid species of Diuraphis spp. were identified: D. muehlei (Börner, 1950 - in 1974, D. bromicola (Hille Ris Lambers, 1959 - in 1988, D. noxia (Kurdjumov, 1913 - in 2003 as a result of systematic and long-term aphid collections. The occurrence of D. noxia presents a particular risk to cereal crops in Poland. This expansive aphid species that originates from Asia and the Mediterranean is a vector of Barley yellow dwarf viruses (BYDV, and has become one of the most important pest of wheat and barley in the world. Changes in climatic conditions that have been observed in recent years in Poland such as hot summer, long and warm autumn, mild winter seem to be optimal for occurrence and development of aphid species from warmer parts of Europe.

  20. Plant genotype shapes ant-aphid interactions: implications for community structure and indirect plant defense.

    Science.gov (United States)

    Mooney, Kailen A; Agrawal, Anurag A

    2008-06-01

    Little is known about the mechanisms by which plant genotype shapes arthropod community structure. In a field experiment, we measured the effects of milkweed (Asclepias syriaca) genotype and ants on milkweed arthropods. Populations of the ant-tended aphid Aphis asclepiadis and the untended aphid Myzocallis asclepiadis varied eight- to 18-fold among milkweed genotypes, depending on aphid species and whether ants were present. There was no milkweed effect on predatory arthropods. Ants increased Aphis abundance 59%, decreased Myzocallis abundance 52%, and decreased predator abundance 56%. Milkweed genotype indirectly influenced ants via direct effects on Aphis and Myzocallis abundance. Milkweed genotype also modified ant-aphid interactions, influencing the number of ants attracted per Aphis and Myzocallis. While ant effects on Myzocallis were consistently negative, effects on Aphis ranged from antagonistic to mutualistic among milkweed genotypes. As a consequence of milkweed effects on ant-aphid interactions, ant abundance varied 13-fold among milkweed genotypes, and monarch caterpillar survival was negatively correlated with genetic variation in ant abundance. We speculate that heritable variation in milkweed phloem sap drives these effects on aphids, ants, and caterpillars. In summary, milkweed exerts genetic control over the interactions between aphids and an ant that provides defense against foliage-feeding caterpillars.

  1. Effects of cutting frequency on alfalfa yield and yield components in ...

    African Journals Online (AJOL)

    Effects of cutting frequency on alfalfa yield and yield components in Songnen Plain, Northeast China. J Chen, F Tang, R Zhu, C Gao, G Di, Y Zhang. Abstract. The productivity and quality of alfalfa (Medicago sativa L.) is strongly influenced by cutting frequency (F). To clarify that the yield and quality of alfalfa if affected by F, ...

  2. Peroxiredoxin 1 protects the pea aphid Acyrthosiphon pisum from oxidative stress induced by Micrococcus luteus infection.

    Science.gov (United States)

    Zhang, Yongdong; Lu, Zhiqiang

    2015-05-01

    Reactive oxygen species (ROSs) are generated in organisms in response to infections caused by invading microbes. However, excessive ROSs will inflict oxidative damage on the host. Peroxiredoxins (Prxs) are antioxidative enzymes that may eliminate ROSs efficiently. In this study, ApPrx1 from the pea aphid Acyrthosiphon pisum was cloned, and its function was investigated in vitro and in vivo. In the presence of DTT, recombinant ApPrx1 protein from Escherichia coli showed antioxidative activity by eliminating H2O2 effectively. The H2O2 levels were significantly higher in Micrococcus luteus-infected aphids than in uninfected aphids, and ApPrx1 expression was remarkably up-regulated when the aphids were infected with M. luteus or injected with H2O2. When ApPrx1 expression was reduced by dsRNA injection, the survival of the aphids decreased significantly after M. luteus infection. Knockdown of ApPrx1 decreased M. luteus loads inside the aphids 48h post-infection. While under infection conditions, the H2O2 levels were much higher in ApPrx1 knockdown aphids than in dsGFP-injected aphids, indicating that the decreased survival of the aphids was caused by increased oxidative stress. Taken together, our results reveal that ApPrx1 plays a protective role in oxidative stress caused by bacterial infection. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Methyl salicylate attracts natural enemies and reduces populations of soybean aphids (Hemiptera: Aphididae) in soybean agroecosystems.

    Science.gov (United States)

    Mallinger, Rachel E; Hogg, David B; Gratton, Claudio

    2011-02-01

    Methyl salicylate, an herbivore-induced plant volatile, has been shown to attract natural enemies and affect herbivore behavior. In this study, methyl salicylate was examined for its attractiveness to natural enemies of the soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), and for its direct effects on soybean aphid population growth rates. Methyl salicylate lures were deployed in plots within organic soybean [Glycine max (L.) Merr.] fields. Sticky card traps adjacent to and 1.5 m from the lure measured the relative abundance of natural enemies, and soybean aphid populations were monitored within treated and untreated plots. In addition, exclusion cage studies were conducted to determine methyl salicylate's effect on soybean aphid population growth rates in the absence of natural enemies. Significantly greater numbers of syrphid flies (Diptera: Syrphidae) and green lacewings (Neuroptera: Chrysopidae) were caught on traps adjacent to the methyl salicylate lure, but no differences in abundance were found at traps 1.5 m from the lure. Furthermore, abundance of soybean aphids was significantly lower in methyl salicylate-treated plots. In exclusion cage studies, soybean aphid numbers were significantly reduced on treated soybean plants when all plants were open to natural enemies. When plants were caged, however, soybean aphid numbers and population growth rates did not differ between treated and untreated plants suggesting no effect of methyl salicylate on soybean aphid reproduction and implicating the role of natural enemies in depressing aphid populations. Although aphid populations were reduced locally around methyl salicylate lures, larger scale studies are needed to assess the technology at the whole-field scale.

  4. The Use of Gene Modification and Advanced Molecular Structure Analyses towards Improving Alfalfa Forage

    Directory of Open Access Journals (Sweden)

    Yaogeng Lei

    2017-01-01

    Full Text Available Abstract: Alfalfa is one of the most important legume forage crops in the world. In spite of its agronomic and nutritive advantages, alfalfa has some limitations in the usage of pasture forage and hay supplement. High rapid degradation of protein in alfalfa poses a risk of rumen bloat to ruminants which could cause huge economic losses for farmers. Coupled with the relatively high lignin content, which impedes the degradation of carbohydrate in rumen, alfalfa has unbalanced and asynchronous degradation ratio of nitrogen to carbohydrate (N/CHO in rumen. Genetic engineering approaches have been used to manipulate the expression of genes involved in important metabolic pathways for the purpose of improving the nutritive value, forage yield, and the ability to resist abiotic stress. Such gene modification could bring molecular structural changes in alfalfa that are detectable by advanced structural analytical techniques. These structural analyses have been employed in assessing alfalfa forage characteristics, allowing for rapid, convenient and cost-effective analysis of alfalfa forage quality. In this article, we review two major obstacles facing alfalfa utilization, namely poor protein utilization and relatively high lignin content, and highlight genetic studies that were performed to overcome these drawbacks, as well as to introduce other improvements to alfalfa quality. We also review the use of advanced molecular structural analysis in the assessment of alfalfa forage for its potential usage in quality selection in alfalfa breeding.

  5. Phytotoxicity of water-soluble substances from alfalfa and barley soil extracts on four crop species.

    Science.gov (United States)

    Read, J J; Jensen, E H

    1989-02-01

    Problems associated with continuously planting alfalfa (Medicago saliva L.) or seeding to thicken depleted alfalfa stands may be due to autotoxicity, an intraspecific form of allelopathy. A bioassay approach was utilized to characterize the specificity and chemical nature of phytotoxins in extracts of alfalfa soils as compared to fallow soil or soil where a cereal was the previous crop. In germination chamber experiments, water-soluble substances present in methanol extracts of soil cropped to alfalfa or barley (Hordeum vulgare L.) decreased seedling root length of alfalfa L-720, winter wheat (Triticum aestivum L. Nugaines) and radish (Raphanus sativa L. Crimson Giant). Five days after germination, seedling dry weights of alfalfa and radish in alfalfa soil extracts were lower compared to wheat or red clover (Trifolium pralense L. Kenland). Growth of red clover was not significantly reduced by soil extracts from cropped soil. Extracts of crop residue screened from soil cropped to alfalfa or barley significantly reduced seedling root length; extracts of alfalfa residue caused a greater inhibition of seedling dry weight than extracts of barely residue. A phytotoxic, unidentified substance present in extracts of crop residue screened from alfalfa soil, which inhibited seedling root length of alfalfa, was isolated by thin-layer chromatography (TLC). Residues from a soil cropped continuously to alfalfa for 10 years had the greatest phytotoxic activity.

  6. Genetic diversity for fermentable carbohydrates production in alfalfa

    Energy Technology Data Exchange (ETDEWEB)

    Castonguay, Y.; Bertrand, A.; Duceppe, M.O.; Dube, M.P.; Michaud, R. [Agriculture and Agri-Food Canada, Quebec City, PQ (Canada)

    2009-07-01

    Alfalfa has many attributes that renders it suitable for bioethanol production, including its adaptability to diverse environmental conditions without any need for nitrogen fertilizer. However research is needed to develop biofuel-type alfalfa with improved biomass production and standability, increased persistence, and better cell wall degradability. The ethanol conversion rates from alfalfa biomass could be increased by genetically improving the accumulation of readily fermentable non-structural carbohydrates (NSC). This presentation reported on a screening project where genotypes with superior cell wall degradability were identified. NSC accumulation within 300 genotypes was randomly selected within six genetic backgrounds from Europe and North America. Biochemical analyses of dried stems revealed a large genetic variability for NSC content, with concentrations ranging from 20 to 100 mg per g DW. NSC variability was considerably higher in a genetic background of European origin compared to the other populations, therefore emphasizing the potential for genetic improvement for that trait. A modified commercial enzymatic cocktail known as AcceleraseTM 1000 Genencor is being developed to optimize the degradation of alfalfa biomass. DNA extracted from genotypes with the highest and lowest cell wall degradability or NSC accumulation will be pooled and used for bulk segregant analysis of DNA polymorphisms using the PCR-based sequence-related amplified polymorphism technique. It was concluded that the commercial release of biofuel-type alfalfa can be accelerated if the genetic markers associated with these traits can be identified.

  7. Ant tending influences soldier production in a social aphid.

    Science.gov (United States)

    Shingleton, A W; Foster, W A

    2000-09-22

    The aphid Pseudoregma sundanica (Van der Goot) (Homoptera: Aphididae) has two defence strategies. It is obligatorily tended by various species of ant and also produces sterile soldiers. We investigated how they allocate their investment in these two strategies. We measured the size, number of soldiers, number and species of tending ant, and number and species of predators in P. sundanica populations. We found that the level of ant tending correlated negatively with soldier investment in P. sundanica. The species of tending ant also influenced soldier investment. We excluded ants from aphid populations and recorded changes in population size and structure over four weeks. Ant exclusion led to population decline and extinction. At the same time, surviving populations showed a significant increase in soldier investment. The data demonstrate that social aphids can adjust their investment in soldiers in direct response to environmental change.

  8. Differential expression of superoxide dismutase genes in aphid-stressed maize (Zea mays L.) seedlings.

    Science.gov (United States)

    Sytykiewicz, Hubert

    2014-01-01

    The aim of this study was to compare the expression patterns of superoxide dismutase genes (sod2, sod3.4, sod9 and sodB) in seedling leaves of the Zea mays L. Tasty Sweet (susceptible) and Ambrozja (relatively resistant) cultivars infested with one of two hemipteran species, namely monophagous Sitobion avenae F. (grain aphid) or oligophagous Rhopalosiphum padi L. (bird cherry-oat aphid). Secondarily, aphid-elicited alternations in the antioxidative capacity towards DPPH (1,1-diphenyl-2-picrylhydrazyl) radical in insect-stressed plants were evaluated. Comprehensive comparison of expression profiles of the four sod genes showed that both insect species evoked significant upregulation of three genes sod2, sod3.4 and sod9). However, aphid infestation affected non-significant fluctuations in expression of sodB gene in seedlings of both maize genotypes. The highest levels of transcript accumulation occurred at 8 h (sod2 and sod3.4) or 24 h (sod9) post-infestation, and aphid-induced changes in the expression of sod genes were more dramatic in the Ambrozja cultivar than in the Tasty Sweet variety. Furthermore, bird cherry-oat aphid colonization had a more substantial impact on levels of DPPH radical scavenging activity in infested host seedlings than grain aphid colonization. Additionally, Ambrozja plants infested by either hemipteran species showed markedly lower antioxidative capacity compared with attacked Tasty Sweet plants.

  9. Differential Expression of Superoxide Dismutase Genes in Aphid-Stressed Maize (Zea mays L.) Seedlings

    Science.gov (United States)

    Sytykiewicz, Hubert

    2014-01-01

    The aim of this study was to compare the expression patterns of superoxide dismutase genes (sod2, sod3.4, sod9 and sodB) in seedling leaves of the Zea mays L. Tasty Sweet (susceptible) and Ambrozja (relatively resistant) cultivars infested with one of two hemipteran species, namely monophagous Sitobion avenae F. (grain aphid) or oligophagous Rhopalosiphum padi L. (bird cherry-oat aphid). Secondarily, aphid-elicited alternations in the antioxidative capacity towards DPPH (1,1-diphenyl-2-picrylhydrazyl) radical in insect-stressed plants were evaluated. Comprehensive comparison of expression profiles of the four sod genes showed that both insect species evoked significant upregulation of three genes sod2, sod3.4 and sod9). However, aphid infestation affected non-significant fluctuations in expression of sodB gene in seedlings of both maize genotypes. The highest levels of transcript accumulation occurred at 8 h (sod2 and sod3.4) or 24 h (sod9) post-infestation, and aphid-induced changes in the expression of sod genes were more dramatic in the Ambrozja cultivar than in the Tasty Sweet variety. Furthermore, bird cherry-oat aphid colonization had a more substantial impact on levels of DPPH radical scavenging activity in infested host seedlings than grain aphid colonization. Additionally, Ambrozja plants infested by either hemipteran species showed markedly lower antioxidative capacity compared with attacked Tasty Sweet plants. PMID:24722734

  10. A magical biological insecticide extracted from seeds of Millettia pachyarpa to kill cabbage aphids

    Science.gov (United States)

    Lin, Tianxing; Gong, Mingfu; Guan, Qinlan

    2018-04-01

    Millettia pachycarpa Benth is a perennial climbing shrub belonging to the genus Millettia, as it is widely used in traditional practices like agricultural pesticides, blood tonics, fish poison, and treatments for cancer and infertility. The crude extract of the seeds of M. pachycarpa had insecticidal activity on cabbage aphids. The conventional extract approach with three kinds of organic solvents: methanol, ethanol, and acetone was used for extracting of crude extract of seeds of M. pachycarpa. The leaf immersion method in a petri dish was used to measure contact activity on cabbage aphids. The field measurement method in a cabbage field was used to measure the control effect. The result indicated that the average mortality rate of cabbage aphids reached 91.3 percent under the action of crude extract of the seeds of M. pachycarpa, indicating that contacting activity against cabbage aphid was strong. After the crude extract was sprayed for 2 days, the proofread control effect of 1000 μg / mL ethanol crude extract against cabbage aphid was 85.0 percent. After 7 days of spraying, this number increased to 92.2 percent. The study concluded that crude extract of the seeds of M. pachyarpa extracted with methanol, ethanol, acetone had demonstrable contact activity against cabbage aphid and 1000 μg / mL ethanol crude extract had significant control effect against the larvae of cabbage aphid.

  11. Pest control of aphids depends on landscape complexity and natural enemy interactions.

    Science.gov (United States)

    Martin, Emily A; Reineking, Björn; Seo, Bumsuk; Steffan-Dewenter, Ingolf

    2015-01-01

    Aphids are a major concern in agricultural crops worldwide, and control by natural enemies is an essential component of the ecological intensification of agriculture. Although the complexity of agricultural landscapes is known to influence natural enemies of pests, few studies have measured the degree of pest control by different enemy guilds across gradients in landscape complexity. Here, we use multiple natural-enemy exclosures replicated in 18 fields across a gradient in landscape complexity to investigate (1) the strength of natural pest control across landscapes, measured as the difference between pest pressure in the presence and in the absence of natural enemies; (2) the differential contributions of natural enemy guilds to pest control, and the nature of their interactions across landscapes. We show that natural pest control of aphids increased up to six-fold from simple to complex landscapes. In the absence of pest control, aphid population growth was higher in complex than simple landscapes, but was reduced by natural enemies to similar growth rates across all landscapes. The effects of enemy guilds were landscape-dependent. Particularly in complex landscapes, total pest control was supplied by the combined contribution of flying insects and ground-dwellers. Birds had little overall impact on aphid control. Despite evidence for intraguild predation of flying insects by ground-dwellers and birds, the overall effect of enemy guilds on aphid control was complementary. Understanding pest control services at large spatial scales is critical to increase the success of ecological intensification schemes. Our results suggest that, where aphids are the main pest of concern, interactions between natural enemies are largely complementary and lead to a strongly positive effect of landscape complexity on pest control. Increasing the availability of seminatural habitats in agricultural landscapes may thus benefit not only natural enemies, but also the effectiveness of

  12. Aphid wing induction and ecological costs of alarm pheromone emission under field conditions.

    Directory of Open Access Journals (Sweden)

    Eduardo Hatano

    2010-06-01

    Full Text Available The pea aphid, Acyrthosiphon pisum Harris, (Homoptera: Aphididae releases the volatile sesquiterpene (E-beta-farnesene (EBF when attacked by a predator, triggering escape responses in the aphid colony. Recently, it was shown that this alarm pheromone also mediates the production of the winged dispersal morph under laboratory conditions. The present work tested the wing-inducing effect of EBF under field conditions. Aphid colonies were exposed to two treatments (control and EBF and tested in two different environmental conditions (field and laboratory. As in previous experiments aphids produced higher proportion of winged morphs among their offspring when exposed to EBF in the laboratory but even under field conditions the proportion of winged offspring was higher after EBF application (6.84+/-0.98% compared to the hexane control (1.54+/-0.25%. In the field, the proportion of adult aphids found on the plant at the end of the experiment was lower in the EBF treatment (58.1+/-5.5% than in the control (66.9+/-4.6%, in contrast to the climate chamber test where the numbers of adult aphids found on the plant at the end of the experiment were, in both treatments, similar to the numbers put on the plant initially. Our results show that the role of EBF in aphid wing induction is also apparent under field conditions and they may indicate a potential cost of EBF emission. They also emphasize the importance of investigating the ecological role of induced defences under field conditions.

  13. Practices that support coexistence: A survey of Alfalfa growers

    Science.gov (United States)

    The alfalfa industry has worked hard to foster the coexistence of genetically-engineered (GE) and conventional alfalfa production by developing a set of best management practices that aim to limit adventitious-presence (AP) of GE traits in conventional seed. The general goal is to minimize transgene...

  14. Over-Expression of Arabidopsis EDT1 Gene Confers Drought Tolerance in Alfalfa (Medicago sativa L.

    Directory of Open Access Journals (Sweden)

    Guangshun Zheng

    2017-12-01

    Full Text Available Alfalfa (Medicago sativa L. is an important legume forage crop with great economic value. However, as the growth of alfalfa is seriously affected by an inadequate supply of water, drought is probably the major abiotic environmental factor that most severely affects alfalfa production worldwide. In an effort to enhance alfalfa drought tolerance, we transformed the Arabidopsis Enhanced Drought Tolerance 1 (AtEDT1 gene into alfalfa via Agrobacterium-mediated transformation. Compared with wild type plants, drought stress treatment resulted in higher survival rates and biomass, but reduced water loss rates in the transgenic plants. Furthermore, transgenic alfalfa plants had increased stomatal size, but reduced stomatal density, and these stomatal changes contributed greatly to reduced water loss from leaves. Importantly, transgenic alfalfa plants exhibited larger root systems with larger root lengths, root weight, and root diameters than wild type plants. The transgenic alfalfa plants had reduced membrane permeability and malondialdehyde content, but higher soluble sugar and proline content, higher superoxide dismutase activity, higher chlorophyll content, enhanced expression of drought-responsive genes, as compared with wild type plants. Notably, transgenic alfalfa plants grew better in a 2-year field trial and showed enhanced growth performance with increased biomass yield. All of our morphological, physiological, and molecular analyses demonstrated that the ectopic expression of AtEDT1 improved growth and enhanced drought tolerance in alfalfa. Our study provides alfalfa germplasm for use in forage improvement programs, and may help to increase alfalfa production in arid lands.

  15. Novel male-biased expression in paralogs of the aphid slimfast nutrient amino acid transporter expansion

    Directory of Open Access Journals (Sweden)

    Nathanson Lubov

    2011-09-01

    Full Text Available Abstract Background A major goal of molecular evolutionary biology is to understand the fate and consequences of duplicated genes. In this context, aphids are intriguing because the newly sequenced pea aphid genome harbors an extraordinary number of lineage-specific gene duplications relative to other insect genomes. Though many of their duplicated genes may be involved in their complex life cycle, duplications in nutrient amino acid transporters appear to be associated rather with their essential amino acid poor diet and the intracellular symbiosis aphids rely on to compensate for dietary deficits. Past work has shown that some duplicated amino acid transporters are highly expressed in the specialized cells housing the symbionts, including a paralog of an aphid-specific expansion homologous to the Drosophila gene slimfast. Previous data provide evidence that these bacteriocyte-expressed transporters mediate amino acid exchange between aphids and their symbionts. Results We report that some nutrient amino acid transporters show male-biased expression. Male-biased expression characterizes three paralogs in the aphid-specific slimfast expansion, and the male-biased expression is conserved across two aphid species for at least two paralogs. One of the male-biased paralogs has additionally experienced an accelerated rate of non-synonymous substitutions. Conclusions This is the first study to document male-biased slimfast expression. Our data suggest that the male-biased aphid slimfast paralogs diverged from their ancestral function to fill a functional role in males. Furthermore, our results provide evidence that members of the slimfast expansion are maintained in the aphid genome not only for the previously hypothesized role in mediating amino acid exchange between the symbiotic partners, but also for sex-specific roles.

  16. Exploring the nitrogen ingestion of aphids--a new method using electrical penetration graph and (15N labelling.

    Directory of Open Access Journals (Sweden)

    Franziska Kuhlmann

    Full Text Available Studying plant-aphid interactions is challenging as aphid feeding is a complex process hidden in the plant tissue. Here we propose a combination of two well established methods to study nutrient acquisition by aphids focusing on the uptake of isotopically labelled nitrogen ((15N. We combined the Electrical Penetration Graph (EPG technique that allows detailed recording of aphid feeding behaviour and stable isotope ratio mass spectrometry (IRMS to precisely measure the uptake of nitrogen. Bird cherry-oat aphids Rhopalosiphum padi L. (Hemiptera, Aphididae fed for 24 h on barley plants (Hordeum vulgare L., cultivar Lina, Poaceae that were cultivated with a (15N enriched nutrient solution. The time aphids fed in the phloem was strongly positive correlated with their (15N uptake. All other single behavioural phases were not correlated with (15N enrichment in the aphids, which corroborates their classification as non-feeding EPG phases. In addition, phloem-feeding and (15N enrichment of aphids was divided into two groups. One group spent only short time in the phloem phase and was unsuccessful in nitrogen acquisition, while the other group displayed longer phloem-feeding phases and was successful in nitrogen acquisition. This suggests that several factors such as the right feeding site, time span of feeding and individual conditions play a role for the aphids to acquire nutrients successfully. The power of this combination of methods for studying plant-aphid interactions is discussed.

  17. Effect of genotype and applied management on alfalfa yield and quality

    Directory of Open Access Journals (Sweden)

    Milić Dragan

    2014-01-01

    Full Text Available It is essential to apply advanced management for successful production of alfalfa hay with premium quality (high content of protein and minerals. The maximum yield and the best quality of alfalfa in Serbia can be obtained by cutting four or five times per year. In alfalfa stands, use of cutting system with three cuts per year is inefficient and does not allow full exploitation of cultivar genetic potential and environmental conditions. It is possible, and economically beneficial to grow alfalfa on pseudoglay soils after application of lime and organic manure, with recommended rates 2.5 t ha-1 lime and 30 t ha-1 manure. Cutting alfalfa at the beginning of flowering stage (5 cuts per year provides hay with better quality - higher content of crude protein and lower portion of fibre fractions (neutral detergent fibre, acid detergent fibre, acid detergent lignin, and there is no reduction in dry matter yield. There is no differences in alfalfa quality after application of lower (2.5 t ha-1 and higher dose (5.0 t ha-1 of lime + 30 t ha-1 of organic manure, but there is significant increase of dry matter yield and protein yield per hectare followed by higher level of metabolic energy per unit area. Upon the results of this study, base of successful alfalfa production would be to develop management system and cultivars for different environments that would maximize hay yields without significant loses of quality.

  18. NDVI to Detect Sugarcane Aphid Injury to Grain Sorghum.

    Science.gov (United States)

    Elliott, N C; Backoulou, G F; Brewer, M J; Giles, K L

    2015-06-01

    Multispectral remote sensing has potential to provide quick and inexpensive information on sugarcane aphid, Melanaphis sacchari (Zehntner), pest status in sorghum fields. We describe a study conducted to determine if injury caused by sugarcane aphid to sorghum plants in fields of grain sorghum could be detected using multispectral remote sensing from a fixed wing aircraft. A study was conducted in commercial grain sorghum fields in the Texas Gulf Coast region in June 2014. Twenty-six commercial grain sorghum fields were selected and rated for the level of injury to sorghum plants in the field caused by sugarcane aphid. Plant growth stage ranged from 5.0 (watery ripe) to 7.0 (hard dough) among fields; and plant injury rating from sugarcane aphid ranged from 1.0 (little or no injury) to 4.0 (>40% of plants displaying injury) among fields. The normalized differenced vegetation index (NDVI) is calculated from light reflectance in the red and near-infrared wavelength bands in multispectral imagery and is a common index of plant stress. High NDVI indicates low levels of stress and low NDVI indicates high stress. NDVI ranged from -0.07 to 0.26 among fields. The correlation between NDVI and plant injury rating was negative and significant, as was the correlation between NDVI and plant growth stage. The negative correlation of NDVI with injury rating indicated that plant stress increased with increasing plant injury. Reduced NDVI with increasing plant growth probably resulted from reduced photosynthetic activity in more mature plants. The correlation between plant injury rating and plant growth stage was positive and significant indicating that plant injury from sugarcane aphid increased as plants matured. The partial correlation of NDVI with plant injury rating was negative and significant indicating that NDVI decreased with increasing plant injury after adjusting for its association with plant growth stage. We demonstrated that remotely sensed imagery acquired from grain

  19. Biological and Molecular Variability of Alfalfa mosaic virus Affecting Alfalfa Crop in Riyadh Region

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    Mohammed A. AL-Saleh

    2013-12-01

    Full Text Available In 2011–2012, sixty nine samples were collected from alfalfa plants showing viral infection symptoms in Riyadh region. Mechanical inoculation with sap prepared from two collected samples out of twenty five possitive for Alfalfa mosaic virus (AMV by ELISA were produced systemic mosaic on Vigna unguiculata and Nicotiana tabacum, local lesion on Chenopodium amaranticolor and C. quinoa. Vicia faba indicator plants that induce mosaic and mottle with AMV-Sagir isolate and no infection with AMV-Wadi aldawasser isolate. Approximately 700-bp was formed by RT-PCR using AMV coat protein specific primer. Samples from infected alfalfa gave positive results, while healthy plant gave negative result using dot blot hybridization assay. The nucleotide sequences of the Saudi isolates were compared with corresponding viral nucleotide sequences reported in GenBank. The obtained results showed that the AMV from Australia, Brazil, Puglia and China had the highest similarity with AMV-Sajer isolate. While, the AMV from Spain and New Zealaland had the lowest similarity with AMV-Sajer and Wadi aldawasser isolates. The data obtained in this study has been deposited in the GenBank under the accession numbers KC434083 and KC434084 for AMV-Sajer and AMV- Wadialdawasser respectively. This is the first report regarding the gnetic make up of AMV in Saudi Arabia.

  20. Agronomy of strip intercropping broccoli with alyssum for biological control of aphids

    Science.gov (United States)

    Organic broccoli growers in California typically control aphids by intercropping broccoli with strips of alyssum (Lobularia maritima (L.) Desv.) which attracts hoverflies (Diptera: Syrphidae) that are important predators of aphids. A three year study with transplanted organic broccoli in Salinas, ...

  1. First report of Pandora neoaphidis resting spore formation in vivo in aphid hosts under field conditions

    Science.gov (United States)

    The entomopathogenic fungus PANDORA NEOAPHIDIS is a recognized pathogen of aphids, causing natural epizootics in aphid populations, and interacts favorably with aphid predators and parasitoids. Survival of entomophthoralean fungi in periods of unsuitable weather conditions or lack of appropriate hos...

  2. The effect of ion-implantation on germination of alfalfa under phenanthrene stress

    International Nuclear Information System (INIS)

    Huang Hong; Wang Naiyan; Huang Jianwei; Liu Xijian; Dou Junfeng; Du Yongchao; Li Shuairan

    2011-01-01

    To investigate mutagenic effects of polycyclic aromatic hydrocarbons (PAHs) degradation plant under phenanthrene stress and to test germination level of alfalfa after ion-implantation alfalfa seeds were irradiated with N + beam. The germination percentage and the root length distribution of alfalfa, which grew in environment with different mass fraction of phenanthrene was investigated, respectively. The results indicated that the relation of dose and germination rate was shown as 'saddle' curve characteristics. It was found that the 5 x 10 15 cm -2 would be the best dose of implantation. And the longest root length was about 10.32 cm. The experiment also showed phenanthrene would have inhibitive effect on germination percentage and root growth of alfalfa. The stress resistance of PAHs with alfalfa could be enhanced by ion implantation. (authors)

  3. Extraordinary proliferation of microorganisms in aposymbiotic pea aphids, Acyrthosiphon pisum.

    Science.gov (United States)

    Nakabachi, Atsushi; Ishikawa, Hajime; Kudo, Toshiaki

    2003-03-01

    Aposymbiotic pea aphids, which were deprived of their intracellular symbiotic bacterium, Buchnera, exhibit growth retardation and no fecundity. High performance liquid chromatographic (HPLC) analysis revealed that these aposymbiotic aphids, when reared on broad bean plants, accumulated a large amount of histamine. To assess the possibility of extraordinary proliferation of microorganisms other than Buchnera, we enumerated eubacteria and fungi in aphids using the real-time quantitative PCR method that targets genes encoding small-subunit rRNAs. The result showed that these microorganisms were extremely abundant in the aposymbiotic aphids reared on plants. Microbial communities in aposymbiotic aphids were further profiled by phylogenetic analysis of small-subunit rDNAs. Of 172 nonchimeric sequences of fungal 18S rDNAs, 138 (80.2%) belonged to the phylum Ascomycota. Among them, 21 clustered within a monophyletic group consisting of insect-pathogenic fungi and yeast-like symbionts of homopteran insects. Thirty-one (18.0%), two (1.2%), and one (0.6%) clones were clustered within the Basidiomycota, Zygomycota, and Oomycota, respectively. Of 167 nonchimeric sequences of eubacterial 16S rDNAs, 84 (50.3%) belonged to the gamma-subdivision of Proteobacteria to which most primary endosymbionts of insects and prolific histamine producers belong. Forty (24.0%), 25 (15.0%), 10 (6.0%), and five (3.0%) clones were clustered within alpha-Proteobacteria, Cytophaga-Flavobacterium-Bacteroides (CFB) group, Actinobacteria, and beta-Proteobacteria, respectively. Three had no phylogenetic association with known taxonomic divisions. None of the sequences studied in this study coincided exactly with those deposited in GenBank.

  4. Single-Feature Polymorphism Discovery in the Transcriptome of Tetraploid Alfalfa

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    S. Samuel Yang

    2009-11-01

    Full Text Available Advances in alfalfa [ (L. subsp. ] breeding, molecular genetics, and genomics have been slow because this crop is an allogamous autotetraploid (2n = 4x = 32 with complex polysomic inheritance and few genomic resources. Increasing cellulose and decreasing lignin in alfalfa stem cell walls would improve this crop as a cellulosic ethanol feedstock. We conducted genome-wide analysis of single-feature polymorphisms (SFPs of two alfalfa genotypes (252, 1283 that differ in stem cell wall lignin and cellulose concentrations. SFP analysis was conducted using the GeneChip (Affymetrix, Santa Clara, CA as a cross-species platform. Analysis of GeneChip expression data files of alfalfa stem internodes of genotypes 252 and 1283 at two growth stages (elongating, post-elongation revealed 10,890 SFPs in 8230 probe sets. Validation analysis by polymerase chain reaction (PCR-sequencing of a random sample of SFPs indicated a 17% false discovery rate. Functional classification and over-representation analysis showed that genes involved in photosynthesis, stress response and cell wall biosynthesis were highly enriched among SFP-harboring genes. The GeneChip is a suitable cross-species platform for detecting SFPs in tetraploid alfalfa.

  5. Aphid thermal tolerance is governed by a point mutation in bacterial symbionts.

    Directory of Open Access Journals (Sweden)

    Helen E Dunbar

    2007-05-01

    Full Text Available Symbiosis is a ubiquitous phenomenon generating biological complexity, affecting adaptation, and expanding ecological capabilities. However, symbionts, which can be subject to genetic limitations such as clonality and genomic degradation, also impose constraints on hosts. A model of obligate symbiosis is that between aphids and the bacterium Buchnera aphidicola, which supplies essential nutrients. We report a mutation in Buchnera of the aphid Acyrthosiphon pisum that recurs in laboratory lines and occurs in field populations. This single nucleotide deletion affects a homopolymeric run within the heat-shock transcriptional promoter for ibpA, encoding a small heat-shock protein. This Buchnera mutation virtually eliminates the transcriptional response of ibpA to heat stress and lowers its expression even at cool or moderate temperatures. Furthermore, this symbiont mutation dramatically affects host fitness in a manner dependent on thermal environment. Following a short heat exposure as juveniles, aphids bearing short-allele symbionts produced few or no progeny and contained almost no Buchnera, in contrast to aphids bearing symbionts without the deletion. Conversely, under constant cool conditions, aphids containing symbionts with the short allele reproduced earlier and maintained higher reproductive rates. The short allele has appreciable frequencies in field populations (up to 20%, further supporting the view that lowering of ibpA expression improves host fitness under some conditions. This recurring Buchnera mutation governs thermal tolerance of aphid hosts. Other cases in which symbiont microevolution has a major effect on host ecological tolerance are likely to be widespread because of the high mutation rates of symbiotic bacteria and their crucial roles in host metabolism and development.

  6. Rapid analysis of hay attributes using NIRS. Final report, Task II alfalfa supply system

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-10-24

    This final report provides technical information on the development of a near infrared reflectance spectroscopy (NIRS) system for the analysis of alfalfa hay. The purpose of the system is to provide consistent quality for processing alfalfa stems for fuel and alfalfa leaf meal products for livestock feed. Project tasks were to: (1) develop an NIRS driven analytical system for analysis of alfalfa hay and processed alfalfa products; (2) assist in hiring a qualified NIRS technician and recommend changes in testing equipment necessary to provide accurate analysis; (3) calibrate the NIRS instrument for accurate analyses; and (4) develop prototype equipment and sampling procedures as a first step towards development of a totally automated sampling system that would rapidly sample and record incoming feedstock and outbound product. An accurate hay testing program was developed, along with calibration equations for analyzing alfalfa hay and sun-cured alfalfa pellets. A preliminary leaf steam calibration protocol was also developed. 7 refs., 11 figs., 10 tabs.

  7. Detection of Norspermidine and Norspermine in Medicago sativa L. (Alfalfa) 1

    Science.gov (United States)

    Rodriguez-Garay, Benjamin; Phillips, Gregory C.; Kuehn, Glenn D.

    1989-01-01

    Shoot meristem tissues of alfalfa, Medicago sativa L., were found by high performance liquid chromatography analyses to contain the uncommon polyamines, norspermidine and norspermine. The chemical structures of norspermidine and norspermine, purified from alfalfa, were confirmed by comparison of mass spectra with those from authentic standards. The discovery of norspermidine and norspermine in alfalfa implicates the presence of at least two biosynthetic enzymes, a polyamine oxidase and a previously uncharacterized aminopropyltransferase. PMID:16666576

  8. Foliar aphid feeding recruits rhizosphere bacteria and primes plant immunity against pathogenic and non-pathogenic bacteria in pepper.

    Science.gov (United States)

    Lee, Boyoung; Lee, Soohyun; Ryu, Choong-Min

    2012-07-01

    Plants modulate defence signalling networks in response to different biotic stresses. The present study evaluated the effect of a phloem-sucking aphid on plant defence mechanisms in pepper (Capsicum annuum) during subsequent pathogen attacks on leaves and rhizosphere bacteria on roots. Plants were pretreated with aphids and/or the chemical trigger benzothiadiazol (BTH) 7 d before being challenged with two pathogenic bacteria, Xanthomonas axonopodis pv. vesicatoria (Xav) as a compatible pathogen and X. axonopodis pv. glycines (Xag) as an incompatible (non-host) pathogen. Disease severity was noticeably lower in aphid- and BTH + aphid-treated plants than in controls. Although treatment with BTH or aphids alone did not affect the hypersensitive response (HR) against Xag strain 8ra, the combination treatment had a synergistic effect on the HR. The aphid population was reduced by BTH pretreatment and by combination treatment with BTH and bacterial pathogens in a synergistic manner. Analysis of the expression of the defence-related genes Capsicum annum pathogenesis-related gene 9 (CaPR9), chitinase 2 (CaCHI2), SAR8·2 and Lipoxygenase1 (CaLOX1) revealed that aphid infestation resulted in the priming of the systemic defence responses against compatible and incompatible pathogens. Conversely, pre-challenge with the compatible pathogen Xav on pepper leaves significantly reduced aphid numbers. Aphid infestation increased the population of the beneficial Bacillus subtilis GB03 but reduced that of the pathogenic Ralstonia solanacearum SL1931. The expression of defence-related genes in the root and leaf after aphid feeding indicated that the above-ground aphid infestation elicited salicylic acid and jasmonic acid signalling throughout the whole plant. The findings of this study show that aphid feeding elicits plant resistance responses and attracts beneficial bacterial populations to help the plant cope with subsequent pathogen attacks.

  9. Unravelling mycorrhiza-induced wheat susceptibility to the English grain aphid Sitobion avenae

    Science.gov (United States)

    Simon, Amma L.; Wellham, Peter A. D.; Aradottir, Gudbjorg I.; Gange, Alan C.

    2017-04-01

    Arbuscular mycorrhizal (AM) fungi are root symbionts that can increase or decrease aphid growth rates and reproduction, but the reason by which this happens is unknown. To investigate the underlying mechanisms of this interaction, we examined the effect of AM fungi on the English Grain aphid (Sitobion avenae) development, reproduction, attraction, settlement and feeding behaviour on two naturally susceptible varieties Triticum aestivum (L.) variety Solstice and T. monococcum MDR037, and two naturally resistant lines, T. monococcum MDR045 and MDR049. Mycorrhizal colonisation increased the attractiveness of T. aestivum var. Solstice to aphids, but there was no effect on aphid development on this variety. Using the Electrical Penetration Graph (EPG) technique, we found that mycorrhizal colonisation increased aphid phloem feeding on T. monococcum MDR037 and MDR045, colonisation also increased growth rate and reproductive success of S. avenae on these varieties. Mycorrhizas increased vascular bundle size, demonstrating that these fungi can influence plant anatomy. We discuss if and how this could be related to an enhanced success rate in phloem feeding in two varieties. Overall, we present and discuss how mycorrhizal fungi can affect the feeding behaviour of S. avenae in wheat, inducing susceptibility in a resistant variety.

  10. Sublethal and hormesis effects of imidacloprid on the soybean aphid Aphis glycines.

    Science.gov (United States)

    Qu, Yanyan; Xiao, Da; Li, Jinyu; Chen, Zhou; Biondi, Antonio; Desneux, Nicolas; Gao, Xiwu; Song, Dunlun

    2015-04-01

    The soybean aphid, Aphis glycines Matsumura, is a major pest in soybean crop. Current management of this pest relies mainly on insecticides applications, and the neonicotinoid imidacloprid has been proposed as an effective insecticide to control A. glycines in soybean field. Imidacloprid at lethal concentrations not only exerts acute toxicity to A. glycines, but also cause various biological changes when aphids are chronically exposed to lower concentrations. In this study, we assessed the effects of a low-lethal (0.20 mg L(-1)) and two sublethal (0.05 and 0.10 mg L(-1)) imidacloprid concentrations on various A. glycines life history traits. Aphid exposure to 0.20 mg L(-1) imidacloprid caused slower juvenile development, shorter reproductive period, and reduced adult longevity, fecundity and total lifespan. Stimulatory effects, i.e. hormesis, on reproduction and immature development duration were observed in aphids exposed to the lower sublethal imidacloprid concentrations. Consequently, the net reproduction rate (R 0) was significantly higher than in the control aphids. These findings stress the importance of the actual imidacloprid concentration in its toxicological properties on A. glycines. Therefore, our results would be useful for assessing the overall effects of imidacloprid on A. glycines and for optimizing integrated pest management programs targeting this pest.

  11. Effects of Alfalfa Meal on Growth Performance and Gastrointestinal Tract Development of Growing Ducks

    Directory of Open Access Journals (Sweden)

    J. F. Jiang

    2012-10-01

    Full Text Available A study was conducted to evaluate effects of alfalfa meal on growth performance and gastrointestinal tract development of growing layer ducks to provide evidence for application of alfalfa meal in the duck industry. Two hundred and fifty-six healthy Shaoxing 7-wk old growing layer ducks were selected and randomly allocated to 1 of 4 dietary treatments based on corn and soybean meal and containing 0, 3, 6, and 9% of alfalfa meal for 8 wks. Each treatment consisted of 4 replicates of 16 ducks each. Briefly, birds were raised in separate compartments, and each compartment consisted of three parts: indoor floor house, adjacent open area and a connecting water area. The results showed: i Growing ducks fed alfalfa meal diet were not significantly different in average daily gain, feed intake and gain-to-feed ratio from those fed no alfalfa diet (p>0.05. ii Alfalfa meal increased the ratio crop, gizzard to live weight, caecum to live weight, the caecum index of growing ducks (p<0.05. iii Villus height in duodenum and jejunum of growing ducks increased significantly with the increase of alfalfa meal levels (p<0.05. Crypt depth in duodenum and jejunum of growing ducks decreased significantly with the increase of alfalfa meal levels (p<0.05. This experiment showed that feeding of alfalfa meal to growing layer ducks could improve gastrointestinal tract growth and small intestinal morphology without effect on performance. This experiment provides evidence that alfalfa meal is a very valuable feedstuff for growing layer ducks.

  12. Unrelated facultative endosymbionts protect aphids against a fungal pathogen.

    Science.gov (United States)

    Łukasik, Piotr; van Asch, Margriet; Guo, Huifang; Ferrari, Julia; Godfray, H Charles J

    2013-02-01

    The importance of microbial facultative endosymbionts to insects is increasingly being recognized, but our understanding of how the fitness effects of infection are distributed across symbiont taxa is limited. In the pea aphid, some of the seven known species of facultative symbionts influence their host's resistance to natural enemies, including parasitoid wasps and a pathogenic fungus. Here we show that protection against this entomopathogen, Pandora neoaphidis, can be conferred by strains of four distantly related symbionts (in the genera Regiella, Rickettsia, Rickettsiella and Spiroplasma). They reduce mortality and also decrease fungal sporulation on dead aphids which may help protect nearby genetically identical insects. Pea aphids thus obtain protection from natural enemies through association with a wider range of microbial associates than has previously been thought. Providing resistance against natural enemies appears to be a particularly common way for facultative endosymbionts to increase in frequency within host populations. © 2012 Blackwell Publishing Ltd/CNRS.

  13. The molecular basis of the interactions between luteoviruses and their aphid vectors

    NARCIS (Netherlands)

    Hogenhout, S.A.

    1999-01-01

    Luteoviruses essentially replicate in the phloem tissue and are transmitted from plant to plant by aphids in a circulative, persistent manner. Virus particles are acquired when aphids feed on phloem sap. Particles are then transported from the midgut or hindgut into the haemolymph and from

  14. Identification of top-down forces regulating cotton aphid population growth in transgenic Bt cotton in central China.

    Directory of Open Access Journals (Sweden)

    Peng Han

    Full Text Available The cotton aphid Aphis gossypii Glover is the main aphid pest in cotton fields in the Yangtze River Valley Cotton-planting Zone (YRZ in central China. Various natural enemies may attack the cotton aphid in Bt cotton fields but no studies have identified potential specific top-down forces that could help manage this pest in the YRZ in China. In order to identify possibilities for managing the cotton aphid, we monitored cotton aphid population dynamics and identified the effect of natural enemies on cotton aphid population growth using various exclusion cages in transgenic Cry1Ac (Bt+CpTI (Cowpea trypsin inhibitor cotton field in 2011. The aphid population growth in the open field (control was significantly lower than those protected or restricted from exposure to natural enemies in the various exclusion cage types tested. The ladybird predator Propylaea japonica Thunberg represented 65% of Coccinellidae predators, and other predators consisted mainly of syrphids (2.1% and spiders (1.5%. The aphid parasitoids Aphidiines represented 76.7% of the total count of the natural enemy guild (mainly Lysiphlebia japonica Ashmead and Binodoxys indicus Subba Rao & Sharma. Our results showed that P. japonica can effectively delay the establishment and subsequent population growth of aphids during the cotton growing season. Aphidiines could also reduce aphid density although their impact may be shadowed by the presence of coccinellids in the open field (likely both owing to resource competition and intraguild predation. The implications of these results are discussed in a framework of the compatibility of transgenic crops and top-down forces exerted by natural enemy guild.

  15. Transcriptomic and proteomic analyses of seasonal photoperiodism in the pea aphid

    Directory of Open Access Journals (Sweden)

    Gauthier J-P

    2009-09-01

    Full Text Available Abstract Background Aphid adaptation to harsh winter conditions is illustrated by an alternation of their reproductive mode. Aphids detect photoperiod shortening by sensing the length of the night and switch from viviparous parthenogenesis in spring and summer, to oviparous sexual reproduction in autumn. The photoperiodic signal is transduced from the head to the reproductive tract to change the fate of the future oocytes from mitotic diploid embryogenesis to haploid formation of gametes. This process takes place in three consecutive generations due to viviparous parthenogenesis. To understand the molecular basis of the switch in the reproductive mode, transcriptomic and proteomic approaches were used to detect significantly regulated transcripts and polypeptides in the heads of the pea aphid Acyrthosiphon pisum. Results The transcriptomic profiles of the heads of the first generation were slightly affected by photoperiod shortening. This suggests that trans-generation signalling between the grand-mothers and the viviparous embryos they contain is not essential. By analogy, many of the genes and some of the proteins regulated in the heads of the second generation are implicated in visual functions, photoreception and cuticle structure. The modification of the cuticle could be accompanied by a down-regulation of the N-β-alanyldopamine pathway and desclerotization. In Drosophila, modification of the insulin pathway could cause a decrease of juvenile hormones in short-day reared aphids. Conclusion This work led to the construction of hypotheses for photoperiodic regulation of the switch of the reproductive mode in aphids.

  16. Gene expression profiles responses to aphid feeding in chrysanthemum (Chrysanthemum morifolium).

    Science.gov (United States)

    Xia, Xiaolong; Shao, Yafeng; Jiang, Jiafu; Ren, Liping; Chen, Fadi; Fang, Weimin; Guan, Zhiyong; Chen, Sumei

    2014-12-02

    Chrysanthemum is an important ornamental plant all over the world. It is easily attacked by aphid, Macrosiphoniella sanbourni. The molecular mechanisms of plant defense responses to aphid are only partially understood. Here, we investigate the gene expression changes in response to aphid feeding in chrysanthemum leaf by RNA-Seq technology. Three libraries were generated from pooled leaf tissues of Chrysanthemum morifolium 'nannongxunzhang' that were collected at different time points with (Y) or without (CK) aphid infestations and mock puncture treatment (Z), and sequenced using an Illumina HiSeqTM 2000 platform. A total of 7,363,292, 7,215,860 and 7,319,841 clean reads were obtained in library CK, Y and Z, respectively. The proportion of clean reads was >97.29% in each library. Approximately 76.35% of the clean reads were mapped to a reference gene database including all known chrysanthemum unigene sequences. 1,157, 527 and 340 differentially expressed genes (DEGs) were identified in the comparison of CK-VS-Y, CK-VS-Z and Z-VS-Y, respectively. These DEGs were involved in phytohormone signaling, cell wall biosynthesis, photosynthesis, reactive oxygen species (ROS) pathway and transcription factor regulatory networks, and so on. Changes in gene expression induced by aphid feeding are shown to be multifaceted. There are various forms of crosstalk between different pathways those genes belonging to, which would allow plants to fine-tune its defense responses.

  17. Mezclas de Alfalfa y Gramíneas en la Serie Sabana de Bogotá Tipo Franco Arcilloso.

    Directory of Open Access Journals (Sweden)

    Chaverra Gil. Hernán

    1960-06-01

    Full Text Available En el Centro Nacional de Investigaciones Agrícolas, Tibaitatá, y en la serie de suelos Sabana de Bogotá, tipo frnaco arcilloso, se llevaron a cabo dos experimentos con mezclas de alfalfa y gramíneas. En el primer ensayo, se sembraron simultáneamente con la alfalfa, ryegrass inglés, rygrass anual y orchoso. Los métodos de siembra utilizados fueron: a alfalfa y gramíneas sembradas al voleo, b alfalfa y gramíneas en el mismo surco, c alfalfa y gramíneas en surcos alternos, d alfalfa en surcos y gramíneas al voleo y e alfalfa en surcos y trébol blanco al voleo. En el segundo experimento se sembró la alfalfa en surcos separados 25 cm. Después de establecida la alfalfa e inmediatamente después del 4° corte se sembraron al voleo las siguientes gramíneas: ryegrass inglés, rygrass anual, orchoro, festuca media, pasto cinta y pasto rescate. Las finalidades del estudio fueron las de valorar el comportamiento de las gramíneas en mezcla con la alfalfa, mediante la determinación progresiva de la composición botánica y el rendimiento de forraje seco de las mezclas. La siembra simultánea de ryegrass inglés y ryegrass anual con la alfalfa dio como resultado una mala población de la leguminosa, especialmente en los dos primeros cortes. La competencia ejercida por estas dos gramíneas a la alfalfa, se redujo casi completamente, cuando se sembraron en surcos alternos o en la alfalfa establecida. Sea cual fuere el pasto sembrado, la siembra de gramíneas en alfalfa establecida, redujo la competencia entre los pastos asociados. En este ensayo el factor más importante en el establecimiento de las gramíneas, fue el agua disponible en el suelo. Bajo las condiciones del primer experimento el orchoro fue la gramínea que mejor creció en asocio de la alfalfa en todos los métodos de siembra estudiado. La producción promedia de la mezcla varió entre 2600 y 3145 Kg/hect. De forreje seco por corte y la proporción de orchoro entre

  18. First report of Pandora neoaphidis resting spore formation in vivo in aphid hosts

    DEFF Research Database (Denmark)

    Clara Scorsetti, Ana; Jensen, Annette Bruun; Lopez Lastra, Claudia

    2012-01-01

    The entomopathogenic fungus Pandora neoaphidis is a recognized pathogen of aphids, causes natural epizootics in aphid populations, and interacts and competes with aphid predators and parasitoids. Survival of entomophthoralean fungi in periods of unsuitable weather conditions or lack of appropriat...

  19. Reproduction and dispersal in an ant-associated root aphid community

    DEFF Research Database (Denmark)

    Ivens, A.B.F.; Kronauer, Daniel Jan Christoph; Pen, I.

    2012-01-01

    viscosity is high and winged aphids rare, consistent with infrequent horizontal transmission between ant host colonies. The absence of the primary host shrub (Pistacia) may explain the absence of sex in three of the studied species, but elm trees (Ulmus) that are primary hosts of the fourth species (T...... above ground, whereas dispersal constraints and dependence on ant-tending may differentially affect the costs and benefits of sex in subterranean aphids. Here, we studied reproductive mode and dispersal in a community of root aphids that are obligately associated with the ant Lasius flavus. We assessed...... the genetic population structure of four species (Geoica utricularia, Tetraneura ulmi, Forda marginata and Forda formicaria) in a Dutch population and found that all species reproduce predominantly if not exclusively asexually, so that populations consist of multiple clonal lineages. We show that population...

  20. The long-term effects of alfalfa on soil water content in the Loess ...

    African Journals Online (AJOL)

    Administrator

    2011-05-23

    May 23, 2011 ... affect the water content in deep soil and continuous growing alfalfa ... Wasteland, wheat field and six seeded alfalfa (Medicago sativa L.) grasslands with ... The crops (wheat, maize, potato, beans and millet) had been rainfed on all ..... Productivity dynamic of alfalfa and its effects on water eco-environment.

  1. Trophic transfer of soil arsenate and associated toxic effects in a plant-aphid-parasitoid system

    Science.gov (United States)

    Lee, Y. S.; Wee, J.; Lee, M.; Hong, J.; Cho, K.

    2017-12-01

    Terrestrial toxic effects of soil arsenic were studied using a model system consisting of soil which artificially treated with arsenic, Capsicum annum,Myzus persicae and Aphidus colemani. We investigated the transfer of arsenic in a soil-plant-aphid system and toxic effect of elevated arsenic through a plant-aphid-parasitoid system. To remove the effect of poor plant growth on aphid performance, test concentrations which have a no effect on health plant growth were selected. Arsenic concentration of growth medium, plant tissues (root, stem, leaf) aphids were measured to observe the arsenic transfer. Correlation matrix was made with arsenic in growth medium which extracted with three extractants (aquaregia, 0.01 M CaCl2 and deionized water), arsenic in plant tissues and plant performance. Toxic effects of elevated arsenic concentrations on each species were investigated at population level. Studied plant performances were dry weight of each tissue, elongation of roots and stems, area of leaves, chlorophyll content of leaves, protein content of leaves and sugar content of leaves. Mean development time, fecundity and honeydew excretion of the aphids and host choice capacity and parasitism success of the parasitoids were examined. In addition, enzyme activities of the plants and the aphids against reactive oxygen species (ROS) induced by arsenic stress were also investigated. The results suggest that arsenic concentration in plant tissues and aphids were elevated with increased concentration of arsenic in soil. Decreased fecundity and honeydew excretion of aphids were observed and decreased eclosion rate of parasitoids were observed with increased arsenic treatment in growth medium. The results showed low concentration of arsenic in soil can transfer through food chain and can impact on higher trophic level species.

  2. Effects of alfalfa meal on the intestinal microbial diversity and immunity of growing ducks.

    Science.gov (United States)

    Jiang, J F; Song, X M; Wu, J L; Jiang, Y Q

    2014-12-01

    This study was conducted to investigate the effects of alfalfa meal diets on the intestinal microbial diversity and immunity of growing egg-type ducks. A total of 128 healthy 7-week-old female egg-type Shaoxing ducks were selected and randomly assigned into four dietary treatments: 0%, 3%, 6% and 9% alfalfa meal for 8 weeks. Each treatment consisted of four replicates of eight ducks each. Polymerase chain reaction denaturing gradient gel electrophoresis (PCR-DGGE) was used to characterize the microbiota. The results showed that the DGGE fingerprints of the V6-V8 fragments of the 16S rRNA from the caeca and faeces of ducks fed 3%, 6% and 9% alfalfa meal had significantly higher microbiota species richness than those fed 0% alfalfa meal (p ducks fed 3%, 6% and 9% alfalfa meal was significantly higher than those fed 0% alfalfa meal (p 0.05), and the 3-9% alfalfa meal did not affect the growth performance of the growing egg-type ducks. The proliferation of T and B lymphocytes was significantly greater (p ducks. Dietary alfalfa meal supplementation increases intestinal microbial community diversity and improves of the immune response growing egg-type ducks. Journal of Animal Physiology and Animal Nutrition © 2014 Blackwell Verlag GmbH.

  3. Production of aerial biomass and equivalent land use in alfalfa (Medicago sativa L.) intercropping

    International Nuclear Information System (INIS)

    Pereyra, T. W.; Pagliaricci, H. R.; Ohanian, A. E.; Bonvillani, M. J.

    2013-01-01

    Productivity increase has traditionally been associated to yield increase through breeding and crop management practices. Nevertheless, if production is considered per area and time unit, the intercropping system may be another way to improve cost-effectiveness. The objective of the experiment was to determine the produced biomass and the equivalent land use in alfalfa (Medicago sativa L.) monocrop and intercrops with sorghum Sudan (Sorghum sudanense L.) and oat (Avena sativa L.). The aerial biomass of all the treatments (expressed per surface unit) and the equivalent land use were determined. The design was completely randomized, arranged in blocks with two repetitions. The results were subject to an ANAVA and the means were compared through Duncan's test, by means of the statistical pack INFOSTAT. The alfalfa-sorghum intercrop triplicated the alfalfa production with regards to the monocrop, while alfalfa-oat did not exceed the production of pure alfalfa in the winter months. The alfalfa-sorghum intercrop was 57 % more efficient in land use than the respective monocrops, while alfalfa-oat did not surpass the unit. (author)

  4. Gas, Stars, and Star Formation in Alfalfa Dwarf Galaxies

    Science.gov (United States)

    Huang, Shan; Haynes, Martha P.; Giovanelli, Riccardo; Brinchmann, Jarle; Stierwalt, Sabrina; Neff, Susan G.

    2012-01-01

    We examine the global properties of the stellar and Hi components of 229 low H i mass dwarf galaxies extracted from the ALFALFA survey, including a complete sample of 176 galaxies with H i masses ALFALFA dwarfs are faint and of low surface brightness; only 56% of those within the SDSS footprint have a counterpart in the SDSS spectroscopic survey. A large fraction of the dwarfs have high specific star formation rates (SSFRs), and estimates of their SFRs and M* obtained by SED fitting are systematically smaller than ones derived via standard formulae assuming a constant SFR. The increased dispersion of the SSFR distribution at M* approximately less than10(exp 8)M(sub 0) is driven by a set of dwarf galaxies that have low gas fractions and SSFRs; some of these are dE/dSphs in the Virgo Cluster. The imposition of an upper Hi mass limit yields the selection of a sample with lower gas fractions for their M* than found for the overall ALFALFA population. Many of the ALFALFA dwarfs, particularly the Virgo members, have H i depletion timescales shorter than a Hubble time. An examination of the dwarf galaxies within the full ALFALFA population in the context of global star formation (SF) laws is consistent with the general assumptions that gas-rich galaxies have lower SF efficiencies than do optically selected populations and that Hi disks are more extended than stellar ones.

  5. Modulation of legume defense signaling pathways by native and non-native pea aphid clones

    Directory of Open Access Journals (Sweden)

    Carlos Sanchez-Arcos

    2016-12-01

    Full Text Available The pea aphid (Acyrthosiphon pisum is a complex of at least 15 genetically different host races that are native to specific legume plants, but can all develop on the universal host plant Vicia faba. Despite much research it is still unclear why pea aphid host races (biotypes are able to colonize their native hosts while other host races are not. All aphids penetrate the plant and salivate into plant cells when they test plant suitability. Thus plants might react differently to the various pea aphid host races. To find out whether legume species vary in their defense responses to different pea aphid host races, we measured the amounts of salicylic acid (SA, the jasmonic acid-isoleucine conjugate (JA-Ile, other jasmonate precursors and derivatives, and abscisic acid (ABA in four different species (Medicago sativa, Trifolium pratense, Pisum sativum, V. faba after infestation by native and non-native pea aphid clones of various host races. Additionally, we assessed the performance of the clones on the four plant species. On M. sativa and T. pratense, non-native clones that were barely able to survive or reproduce, triggered a strong SA and JA-Ile response, whereas infestation with native clones led to lower levels of both phytohormones. On P. sativum, non-native clones, which survived or reproduced to a certain extent, induced fluctuating SA and JA-Ile levels, whereas the native clone triggered only a weak SA and JA-Ile response. On the universal host V. faba all aphid clones triggered only low SA levels initially, but induced clone-specific patterns of SA and JA-Ile later on. The levels of the active JA-Ile conjugate and of the other JA-pathway metabolites measured showed in many cases similar patterns, suggesting that the reduction in JA signaling was due to an effect upstream of OPDA. ABA levels were downregulated in all aphid clone-plant combinations and were therefore probably not decisive factors for aphid-plant compatibility. Our results

  6. Relationships of Lower Invertebrates Aphid Ecology

    African Journals Online (AJOL)

    or even males for a single species of the about 4(XX) described thus far. Nonetheless, Professor ... the aphid armoury is dispersal, an adaptation related to total habitat quality and ... It also considers predator - prey interactions and the possible ...

  7. Ecdysone signaling underlies the pea aphid transgenerational wing polyphenism.

    Science.gov (United States)

    Vellichirammal, Neetha Nanoth; Gupta, Purba; Hall, Tannice A; Brisson, Jennifer A

    2017-02-07

    The wing polyphenism of pea aphids is a compelling laboratory model with which to study the molecular mechanisms underlying phenotypic plasticity. In this polyphenism, environmental stressors such as high aphid density cause asexual, viviparous adult female aphids to alter the developmental fate of their embryos from wingless to winged morphs. This polyphenism is transgenerational, in that the pea aphid mother experiences the environmental signals, but it is her offspring that are affected. Previous research suggested that the steroid hormone ecdysone may play a role in this polyphenism. Here, we analyzed ecdysone-related gene expression patterns and found that they were consistent with a down-regulation of the ecdysone pathway being involved in the production of winged offspring. We therefore predicted that reduced ecdysone signaling would result in more winged offspring. Experimental injections of ecdysone or its analog resulted in a decreased production of winged offspring. Conversely, interfering with ecdysone signaling using an ecdysone receptor antagonist or knocking down the ecdysone receptor gene with RNAi resulted in an increased production of winged offspring. Our results are therefore consistent with the idea that ecdysone plays a causative role in the regulation of the proportion of winged offspring produced in response to crowding in this polyphenism. Our results also show that an environmentally regulated maternal hormone can mediate phenotype production in the next generation, as well as provide significant insight into the molecular mechanisms underlying the functioning of transgenerational phenotypic plasticity.

  8. National Plant Diagnostic Network, Taxonomic training videos: Aphids under the microscope - Cerataphis brasiliensis

    Science.gov (United States)

    Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides provides training to identify the palm aphid, Cerataphis brasiliensis, using a compound microscope and an electronic identification key called “LUCID.” The video demonstrates key morphological structures...

  9. Alfalfa virus S, a new species in the family Alphaflexiviridae

    Science.gov (United States)

    A new species of the family Alphaflexiviridae provisionally named alfalfa virus S (AVS) was discovered in alfalfa samples originating from Sudan. A complete nucleotide sequence of the viral genome consisting of 8,349 nucleotides excluding the 3’ poly(A) tail was determined by high throughput sequenc...

  10. AtWRKY22 promotes susceptibility to aphids and modulates salicylic acid and jasmonic acid signalling.

    Science.gov (United States)

    Kloth, Karen J; Wiegers, Gerrie L; Busscher-Lange, Jacqueline; van Haarst, Jan C; Kruijer, Willem; Bouwmeester, Harro J; Dicke, Marcel; Jongsma, Maarten A

    2016-05-01

    Aphids induce many transcriptional perturbations in their host plants, but the signalling cascades responsible and the effects on plant resistance are largely unknown. Through a genome-wide association (GWA) mapping study in Arabidopsis thaliana, we identified WRKY22 as a candidate gene associated with feeding behaviour of the green peach aphid, Myzus persicae The transcription factor WRKY22 is known to be involved in pathogen-triggered immunity, and WRKY22 gene expression has been shown to be induced by aphids. Assessment of aphid population development and feeding behaviour on knockout mutants and overexpression lines showed that WRKY22 increases susceptibility to M. persicae via a mesophyll-located mechanism. mRNA sequencing analysis of aphid-infested wrky22 knockout plants revealed the up-regulation of genes involved in salicylic acid (SA) signalling and down-regulation of genes involved in plant growth and cell-wall loosening. In addition, mechanostimulation of knockout plants by clip cages up-regulated jasmonic acid (JA)-responsive genes, resulting in substantial negative JA-SA crosstalk. Based on this and previous studies, WRKY22 is considered to modulate the interplay between the SA and JA pathways in response to a wide range of biotic and abiotic stimuli. Its induction by aphids and its role in suppressing SA and JA signalling make WRKY22 a potential target for aphids to manipulate host plant defences. © The Author 2016. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  11. Foliar methyl salicylate emissions indicate prolonged aphid infestation on silver birch and black alder.

    Science.gov (United States)

    Blande, James D; Korjus, Minna; Holopainen, Jarmo K

    2010-03-01

    It is well documented that when plants are damaged by insects they respond by emitting a range of volatile organic compounds (VOCs). While there have been numerous reports concerning VOCs induced by chewing herbivores, there are relatively few studies detailing the VOCs induced by aphid feeding. The effects of aphid feeding on VOCs emitted by boreal forest trees have been particularly neglected. Herbivore-induced VOCs have relevance to direct and indirect plant defence and atmospheric chemistry. In this study, we analysed the VOCs emitted by Betula pendula (Roth) and Alnus glutinosa (L.) (Gaertn.) infested by specialist aphid species under laboratory conditions. We also complemented this by collecting VOCs from leaf beetle-damaged saplings under field conditions. In addition to induction of some inducible terpenes, we detected substantial aphid-induced emissions of methyl salicylate (MeSA) in both B. pendula and A. glutinosa. MeSA emission intensity depended on the length of aphid infestation. Feeding by beetles induced emission of (E)-DMNT in both tree species and (E)-beta-ocimene in A. glutinosa but had no effect on MeSA emissions. MeSA has been shown to have aphid-repellent qualities and has been shown recently to have impact on formation of secondary organic aerosols in the atmosphere. We discuss our results in relation to these two phenomena.

  12. 75 FR 8299 - Draft Environmental Impact Statement; Determination of Regulated Status of Alfalfa Genetically...

    Science.gov (United States)

    2010-02-24

    ...] Draft Environmental Impact Statement; Determination of Regulated Status of Alfalfa Genetically... making a determination on the status of the Monsanto Company and Forage Genetics International alfalfa... status of the Monsanto Company and Forage Genetics International alfalfa lines designated as events J101...

  13. The Use of Gene Modification and Advanced Molecular Structure Analyses towards Improving Alfalfa Forage

    OpenAIRE

    Lei, Yaogeng; Hannoufa, Abdelali; Yu, Peiqiang

    2017-01-01

    Abstract: Alfalfa is one of the most important legume forage crops in the world. In spite of its agronomic and nutritive advantages, alfalfa has some limitations in the usage of pasture forage and hay supplement. High rapid degradation of protein in alfalfa poses a risk of rumen bloat to ruminants which could cause huge economic losses for farmers. Coupled with the relatively high lignin content, which impedes the degradation of carbohydrate in rumen, alfalfa has unbalanced and asynchronous d...

  14. Evidence for an invasive aphid "superclone": extremely low genetic diversity in Oleander aphid (Aphis nerii populations in the southern United States.

    Directory of Open Access Journals (Sweden)

    John Scott Harrison

    2011-03-01

    Full Text Available The importance of genetic diversity in successful biological invasions is unclear. In animals, but not necessarily plants, increased genetic diversity is generally associated with successful colonization and establishment of novel habitats. The Oleander aphid, Aphis nerii, though native to the Mediterranean region, is an invasive pest species throughout much of the world. Feeding primarily on Oleander (Nerium oleander and Milkweed (Asclepias spp. under natural conditions, these plants are unlikely to support aphid populations year round in the southern US. The objective of this study was to describe the genetic variation within and among US populations of A. nerii, during extinction/recolonization events, to better understand the population ecology of this invasive species.We used five microsatellite markers to assess genetic diversity over a two year period within and among three aphid populations separated by small (100 km and large (3,700 km geographic distances on two host plant species. Here we provide evidence for A. nerii "superclones". Genotypic variation was absent in all populations (i.e., each population consisted of a single multilocus genotype (MLG or "clone" and the genetic composition of only one population completely changed across years. There was no evidence of sexual reproduction or host races on different plant species.Aphis nerii is a well established invasive species despite having extremely low genetic diversity. As this aphid appears to be obligatorily asexual, it may share more similarities with clonally reproducing invasive plants, than with other animals. Patterns of temporal and geographic genetic variation, viewed in the context of its population dynamics, have important implications for the management of invasive pests and the evolutionary biology of asexual species.

  15. Coexistence of three specialist aphids on common milkweed, Asclepias syriaca.

    Science.gov (United States)

    Smith, R A; Mooney, K A; Agrawal, A A

    2008-08-01

    Coexistence of host-specific herbivores on plants is believed to be governed by interspecific interactions, but few empirical studies have systematically unraveled these dynamics. We investigated the role of several factors in promoting coexistence among the aphids Aphis nerii, Aphis asclepiadis, and Myzocallis asclepiadis that all specialize on common milkweed (Asclepias syriaca). Competitive exclusion is thought to occur when interspecific competition is stronger than intraspecific competition. Consequently, we investigated whether predators, mutualists, or resource quality affected the strength of intra- vs. interspecific competition among aphids in factorial manipulations of competition with exposure to predation, ants, and variable plant genotypes in three separate experiments. In the predation x competition experiment, predators reduced aphid per capita growth by 66%, but the strength of intra- and interspecific competition did not depend on predators. In the ants x competition experiment, ants reduced per capita growth of A. nerii and M. asclepiadis (neither of which were mutualists with ants) by approximately one-half. In so doing, ants ameliorated the negative effects of these competitors on ant-tended A. asclepiadis by two-thirds, representing a novel benefit of ant-aphid mutualism. Nevertheless, ants alone did not explain the persistence of competitively inferior A. asclepiadis as, even in the presence of ants, interspecific competition remained stronger than intraspecific competition. In the plant genotype x competition experiment, both A. asclepiadis and M. asclepiadis were competitively inferior to A. nerii, with the strength of interspecific competition exceeding that of intraspecific competition by 83% and 23%, respectively. Yet these effects differed among milkweed genotypes, and there were one or more plant genotypes for each aphid species where coexistence was predicted. A synthesis of our results shows that predators play little or no role in

  16. National Plant Diagnostic Network, Taxonomic training videos: Aphids under the microscope - Aphis gossypii

    Science.gov (United States)

    Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides provides training to identify the cotton aphid, Aphis gossypii, using a compound microscope and an electronic identification key called “LUCID.” The video demonstrates key morphological structures that ca...

  17. National Plant Diagnostic Network, Taxonomic training videos: Aphids under the microscope - Myzus persicae

    Science.gov (United States)

    Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides provides training to identify the green peach aphid, Myzus persicae, using a compound microscope and an electronic identification key called “LUCID.” The video demonstrates key morphological structures t...

  18. Plant resistance in sorghums to the sugarcane aphid Melanaphis sacchari (Hemiptera: Aphididae)

    Science.gov (United States)

    We evaluated ten sorghum lines that were near or in commercial release with the intent of identifying phenotypic expression of host-plant resistance to the sugarcane aphid. Two of the ten entries OL2042 and SP7715 expressed a high degree of resistance to the sugarcane aphid with damage ratings <3.0...

  19. Molecular systematics of aphids (Homoptera: Aphididae): new insights from the long-wavelength opsin gene.

    Science.gov (United States)

    Ortiz-Rivas, Benjamín; Moya, Andrés; Martínez-Torres, David

    2004-01-01

    Viviparous aphids (Aphididae) constitute a monophyletic group within the Homoptera with more than 4000 extant species worldwide but higher diversity in temperate regions. Several aspects of their biology account for attention paid to this group of insects. Their plant-sap-sucking way of feeding with many species transmitting viruses to crop plants has important implications on crop management strategies. Cyclical parthenogenesis associated in many groups to host alternation and elaborate polyphenisms is of special interests for evolutionists. Finally, the ancient association of most aphid species with intracellular endosymbiotic bacteria (Buchnera sp.) has also received much attention from evolutionists interested in mechanisms involved in the symbiotic process. Knowing the phylogenetic relationships among major aphid taxa is of special interest to evolutionists interested in the above issues. However, until recently, molecular approaches to aphid phylogeny were absent and discussions on the evolution of aphid life-cycles and on evolutionary aspects of their symbiotic association with Buchnera were framed by morphology-based phylogenies. Recently, two reports using molecular approaches attempted to address the yet unresolved phylogeny of Aphididae with limited although somehow different conclusions. In the present report we study the utility of the long-wave opsin gene in resolving phylogenetic relationships among seven subfamilies within the Aphididae. Our results corroborate some previously proposed relationships and suggest a revision of some others. In particular, our data support grouping the analysed aphid species into three main clades, being the subfamily Lachninae one of them, which contradicts its generally accepted sistership relationship with the subfamily Aphidinae. Moreover, our data also suggest a basal position of Lachninae which has implications on current discussions about the ancestrality of conifer-feeding in modern aphids.

  20. The phytopathogen Dickeya dadantii (Erwinia chrysanthemi 3937) is a pathogen of the pea aphid.

    Science.gov (United States)

    Grenier, Anne-Marie; Duport, Gabrielle; Pagès, Sylvie; Condemine, Guy; Rahbé, Yvan

    2006-03-01

    Dickeya dadantii (Erwinia chrysanthemi) is a phytopathogenic bacterium causing soft rot diseases on many crops. The sequencing of its genome identified four genes encoding homologues of the Cyt family of insecticidal toxins from Bacillus thuringiensis, which are not present in the close relative Pectobacterium carotovorum subsp. atrosepticum. The pathogenicity of D. dadantii was tested on the pea aphid Acyrthosiphon pisum, and the bacterium was shown to be highly virulent for this insect, either by septic injury or by oral infection. The lethal inoculum dose was calculated to be as low as 10 ingested bacterial cells. A D. dadantii mutant with the four cytotoxin genes deleted showed a reduced per os virulence for A. pisum, highlighting the potential role of at least one of these genes in pathogenicity. Since only one bacterial pathogen of aphids has been previously described (Erwinia aphidicola), other species from the same bacterial group were tested. The pathogenic trait for aphids was shown to be widespread, albeit variable, within the phytopathogens, with no link to phylogenetic positioning in the Enterobacteriaceae. Previously characterized gut symbionts from thrips (Erwinia/Pantoea group) were also highly pathogenic to the aphid, whereas the potent entomopathogen Photorhabdus luminescens was not. D. dadantii is not a generalist insect pathogen, since it has low pathogenicity for three other insect species (Drosophila melanogaster, Sitophilus oryzae, and Spodoptera littoralis). D. dadantii was one of the most virulent aphid pathogens in our screening, and it was active on most aphid instars, except for the first one, probably due to anatomical filtering. The observed difference in virulence toward apterous and winged aphids may have an ecological impact, and this deserves specific attention in future research.

  1. The utilization of alfalfa that planted at Tobasa highland, North Sumatra for growing Boerka goat feed

    Directory of Open Access Journals (Sweden)

    Juniar Sirait

    2011-12-01

    Full Text Available Alfalfa (Medicago sativa L. is a herbaceus legume which is potential to be used as goat feed for it’s high production and nutritive value. This research was aimed to study the adaptation of alfalfa planted at highland-moderate climate and it’s utilization for goat feed. This research concists of two activities, ie 1 Agronomy of alfalfa that adapted to highland as a goat feed resource, and 2 The alfalfa usage technology as goat feed. On the first activity alfalfa was planted on highland-moderate climate Gurgur, Tobasa District, North Sumatra Province. Data was collected included: growth percentage, morphology and production aspects, and nutritive value. The harvesting was conducted for three times, where the first cutting had done at 100 days after planting. Investigation of morphology characterirtics was done before alfalfa harvesting. The utilization of alfalfa as goat feed was carried out on the second activity which was arranged in a completely randomized design. Twenty male Boer x Kacang crossbred (Boerka goats of 5-6 months of age with average body weight 14.2±0.8 kg were randomly assigned to four feed treatments where each treatment consited of five replications. The four feed treatments were: P1 = 100% grass + 0% alfalfa; P2 = 90% grass + 10% alfalfa, P3 = 80% grass + 20% alfalfa, and P4 = 70% grass + 30% alfalfa. Data observation included dry matter intake, average daily gain, feed efficiency, and income over feed cost. Results showed that alfalfa growth percentage was 65% with good growth and high either production or nutritive value. The average shoot dry matter production was 438.6 g/m2 which was equivalent to 26.3 t/ha/yr. The crude protein content of alfalfa on the first, second and third harvesting were 17.93; 21.89 and 17.73 per cent, respectively. The utilization of alfalfa that had been processed to be crude-meal can be applied as goat feed. Supplementation of 70% grass and 30% alfalfa meal showed the best results: ADG 59

  2. Application of corn meal at ensiling of alfalfa cocksfoot and their mixture

    Directory of Open Access Journals (Sweden)

    Knežević Jasmin A.

    2014-01-01

    Full Text Available One of the solutions for the economical use of alfalfa and cocksfoot is making the silage. However, these plant species are difficult to be conserved without appropriate additives. The aim of this study was to determine the impact addition of cornmeal on the quality of silage of alfalfa (Medicago sativa L. cv. Kruševačka 22, cocksfoot (Dactilys glomerata L. cv. Kruševačka 40 and their mixture (50% alfalfa, 50% cocksfoot. Mowing both species was carried out at the stage when 1/3 to 1/5 of the plants were in flowering in alfalfa or in stage appearance of inflorescence with cocksfoot. Corn grain is ground at the mill with a sieve ø 2 mm, then mixed with chopped fodder of alfalfa, cocksfoot and the mixture in the following amount: 6% (treatment A2, 3% (treatment A1, and without cornmeal addition (control A0. After six months was determined silage quality. Cornmeal addition, according to the basic indicators of the quality of silage had a significant impact on changing the quality silage of alfalfa, cocksfoot and their mixtures. It is evident that the addition cornmeal addition a significant impact on increasing the energy value (primarily the content inside BEM of silage in all studied treatments.

  3. 75 FR 1585 - Draft Environmental Impact Statement; Determination of Regulated Status of Alfalfa Genetically...

    Science.gov (United States)

    2010-01-12

    ...] Draft Environmental Impact Statement; Determination of Regulated Status of Alfalfa Genetically... and Forage Genetics International alfalfa lines designated as events J101 and J163 as regulated... International (FGI) alfalfa events J101 and J163 were no longer considered regulated articles under the...

  4. Co-inoculation of arbusculr mycorrhizae and nitrogen fixing bacteria enhance alfalfa yield under saline conditions

    International Nuclear Information System (INIS)

    Zhu, R.; Tang, F.; Liu, F.; Chen, J.

    2016-01-01

    The study was to investigate the effects of combined inoculation of Glomus mosseae (arbusculr mycorrhizae fungi, AMF) and Sinorhizobium meliloti (nitrogen-fixing bacteria, i.e., an Rhizobium meliloti, RM) on yield, nutrient contents, nodulation and mycorrhizal colonization of different alfalfa cultivars under saline conditions. An experiment was conducted to test the efficacy of AMF and RM inoculation in development of salt tolerance in alfalfa cultivars (Zhaodong, Nongjing and Longmu) under different salinity levels (0, 60, 120 and 180 mM NaCl). We found that under non stress condition, double inoculation of alfalfa with rhizobium and AM increased the alfalfa yield, nodule weight and number, as well as shoot proline contents, the most when plants were double inoculated followed by AM and rhizobium inoculation, respectively. Whereas under salinity condition, double inoculation of alfalfa with rhizobium and AM increased alfalfa yield, mycorrhizal infection, nodule weight and number as well as increased in shoot proline content, the most followed by AM and rhizobium inoculation, respectively. The Results suggest that growth of alfalfa may be improved by combined inoculation of alfalfa with AM and rhizobium under salt and non-stress conditions. Alleviation of alfalfa growth under saline condition was perhaps due to an increase in mycorrhizal infection and nodule weight and number as well as an increased in shoot proline content by dual inoculation. (author)

  5. Spatial Distribution and Sampling Plans With Fixed Level of Precision for Citrus Aphids (Hom., Aphididae) on Two Orange Species.

    Science.gov (United States)

    Kafeshani, Farzaneh Alizadeh; Rajabpour, Ali; Aghajanzadeh, Sirous; Gholamian, Esmaeil; Farkhari, Mohammad

    2018-04-02

    Aphis spiraecola Patch, Aphis gossypii Glover, and Toxoptera aurantii Boyer de Fonscolombe are three important aphid pests of citrus orchards. In this study, spatial distributions of the aphids on two orange species, Satsuma mandarin and Thomson navel, were evaluated using Taylor's power law and Iwao's patchiness. In addition, a fixed-precision sequential sampling plant was developed for each species on the host plant by Green's model at precision levels of 0.25 and 0.1. The results revealed that spatial distribution parameters and therefore the sampling plan were significantly different according to aphid and host plant species. Taylor's power law provides a better fit for the data than Iwao's patchiness regression. Except T. aurantii on Thomson navel orange, spatial distribution patterns of the aphids were aggregative on both citrus. T. aurantii had regular dispersion pattern on Thomson navel orange. Optimum sample size of the aphids varied from 30-2061 and 1-1622 shoots on Satsuma mandarin and Thomson navel orange based on aphid species and desired precision level. Calculated stop lines of the aphid species on Satsuma mandarin and Thomson navel orange ranged from 0.48 to 19 and 0.19 to 80.4 aphids per 24 shoots according to aphid species and desired precision level. The performance of the sampling plan was validated by resampling analysis using resampling for validation of sampling plans (RVSP) software. This sampling program is useful for IPM program of the aphids in citrus orchards.

  6. Yield, yield components and dry matter digestibility of alfalfa experimental populations

    Directory of Open Access Journals (Sweden)

    Katić Slobodan

    2010-01-01

    Full Text Available Alfalfa is the most important forage crop grown in the temperate regions. It is cultivated for production of vegetative aerial mass used fresh or as hay, and recently as haylage and silage. In many centres worldwide, efforts are made to breed and create new alfalfa cultivars with both higher yields and of higher nutritional value. The aim of this paper was to determine yield and digestibility of 12 experimental populations of alfalfa, and to compare their results to the yields of well-known domestic alfalfa commercial cultivars. The results show significant differences in yield of green forage and dry matter among alfalfa populations, as well as in yield components, height, proportion of leaves in yield and growth rate (tab. 1, 2 and 3. Differences between in vitro digestible dry matter (% and yields of in vitro digestible dry matter (t ha-1 were also significant (tab. 5 and 6. Yield and quality of experimental populations were at the same level or higher than of control cultivars. Synthetic SINUSA exceeded the control cutivars (NS Mediana ZMS V and Banat VS in yield and quality of dry matter. .

  7. Monitoring of aphid flight activities in seed potato crops in Serbia

    Directory of Open Access Journals (Sweden)

    Andja Vucetic

    2013-07-01

    Full Text Available Aphid flight activities in seed potato fields have been studied by the yellow water traps. It is a good method for monitoring aphids as vectors of viruses, but this study also showed it is a suitable method for insect-diversity research. During the four-year studies, over 11.500 specimens were collected and a total of 107 different taxa of aphids were identified. The most abundant species were polyphagous species, such as: Acyrthosiphon pisum (Haris, Aphis fabae Scopoli, Aphis gossypii Glover and Brachycaudus helichrysi (Kaltenbach. The results of the studies show that diversity of aphids in different regions of Serbia is similar regardless of the altitude and the diversity of terrain. At most sites it ranged from 2 to 3. The highest value was recorded in Begeč, locality in northern part of Serbia, in year 2008, and it was 2.92. The maximum values of the Shannon-Weaver diversity index at all sites were recorded in the first weeks of the monitoring of aphid flight activities. Morisita-Horn similarity index shows no significant differences between sites regardless of altitudes. The sites are grouped by year, not by similarity of relief. In spite of these results, the Chi-square analysis showed highly significant difference in vector frequencies among seasons and sites with more pronounced differences for PVY. As a consequence of differences in vector frequencies, the vector pressure index in some regions was different also. The number of vectors and vector pressure index vary depending on the altitude of localities. At localities at altitudes under 1000 m, they were high. The highest index was at Kotraža, locality in central part of Serbia, in 2007, when PVY index exceeded the value of 180, while for PLRV it was 60. At high altitudes on mountain Golija, above 1100 m, the number of aphids was low, as well as the vector pressure index which indicates that these regions are suitable for producing virus-free seed potato.

  8. Effect of planting patterns on dinitrogen fixation of alfalfa and transfer of N fixed

    International Nuclear Information System (INIS)

    Yao Yunyin; Chen Ming; Zhang Xizhong

    1993-01-01

    Contribution of symbiotic nitrogen fixation of alfalfa grown with different planting patterns was studied in a field experiment. %Ndfa and Ndfa in alfalfa and N transferred from alfalfa in meadow fescue were examined by 2 kinds of 15 N tracer techniques. The superiority of mixed culture of legumes with grasses to monoculture was influenced by planting patterns. Biomass in a mixed culture was related to proportion of alfalfa in it. The proportion of alfalfa was in close relationship not only with ratio of their seeds, but also with planting patterns. Row seeding in mixed seeds was better than broadcasting or intercropping in hay yield, total N yield and %Ndfa and Ndfa. It was also higher than the average of corresponding item of alfalfa and meadow fescue in monoculture each equal area. There was no significantly difference (P 15 N isotope dilution method and natural 1 '5N abundance method. N in meadow fescue transferred from alfalfa could be accurately determined by 15 N isotope diffusion method, but 15 N abundance method gave underestimates, even could not examined N in grasses transferred from associated legumes

  9. Role of syrphid larvae and other predators in suppressing aphid infestations in organic lettuce on California's Central Coast.

    Science.gov (United States)

    Smith, Hugh A; Chaney, William E; Bensen, Tiffany A

    2008-10-01

    Organic lettuce, Lactuca sativa L., growers on the Central Coast of California rely on conservation biological control to manage Nasonovia ribisnigri Mosley (Hemiptera: Aphididae) and other aphid pests of lettuce. In 2006, we carried out five replicated field trials to determine the importance of syrphid larvae in the suppression of N. ribisnigri and other aphids infesting organic romaine lettuce. We used Entrust, a spinosad-based insecticide approved for use on organic farms, to suppress syrphid larvae in aphid-infested romaine. Romaine treated with Entrust was unmarketable at harvest because of aphid infestation, whereas insecticide-free romaine was marketable. Syrphid larvae composed 85% or more of total predators in most trials, and they were the only predators consistently recovered from romaine that was infested with aphids early and largely aphid-free by harvest. The species mix of nonsyrphid predators varied from site to site. Applications of Entrust suppressed nonsyrphid predators in two trials, and so was an imperfect tool for selectively suppressing syrphid larvae. The relative importance of syrphid larvae and other predators in the conservation biological control of aphids in organic romaine is discussed. We conclude that syrphid larvae are primarily responsible for the suppression of aphids in organic romaine on California's Central Coast.

  10. Investigation into the effects of ionizing radiations on growth, development and productivity of alfalfa

    International Nuclear Information System (INIS)

    Mirchev, M.; Antonova, N.

    1974-01-01

    The purpose of this study was to establish optimal doses of gamma radiation for the normal growth and development of alfalfa and for securing the highest possible yields of hay and seed. It is concluded that: presowing irradiation of alfalfa seeds from a Cs 137 source has a beneficial effect on alfalfa growth and development and on the yields of alfalfa hay and seeds; the optimal radiation dose for seeds is 1300 rad; the irradiated seeds retain their germinating power. (E.T.)

  11. Presence of the aphid, Chaetosiphon fragaefolii, on strawberry in Argentina.

    Science.gov (United States)

    Cédola, Claudia; Grecob, Nancy

    2010-01-01

    Seasonal abundance of the strawberry aphid complex under different agronomic practices in the outskirts of La Plata, Argentina was studied on strawberry, Fragaria x ananassa Duchesne (Rosales: Rosaceae). Aphid densities were low in strawberry fields in which insecticides and fungicides were used. In addition to Aphis gossypii, Aphis fabae, Mysus persicae and Macrosiphum euphorbiae, the aphid, Chaetosiphon fragaefolii (Cockerell) (Homoptera: Aphididae), was recorded for the first time in this horticultural area. Life history and some demographic parameters were calculated for C. fragaefolii. The mean duration of nymphal stages was 10.44 days, the oviposition period was 11.8 days, and the mean number of nymph/female/day was 2.4 +/- 0.3. Demographic parameters analyzed included the net reproductive rate R(o) = 14.55 +/- 0.096 nymph/female, generation time T=16.91 +/- 0.035 days, and the intrinsic rate of increase r(m) = 0.158 +/- (0.004). No parasites were found associated with C. fragaefolli. The pathogenic fungus, Entomophthora planchoniana Cornu (Zygomycetes: Entomophthorales) was the main mortality factor. Although aphids are not the main pests in strawberry fields, C. fragaefolii can be a serious problem because it can transmit several virus diseases of strawberry. Greater knowledge of life history traits and mortality factors of this species is needed in order to design appropriate control strategies.

  12. Roadside alfalfa: Innocent bystanders or conveyers of genetically-engineered traits?

    Science.gov (United States)

    Clumps of alfalfa are a common sight along roads and vacant lots in areas that grow alfalfa for hay or seed. So what role do feral roadside plants play in dispersing transgenes? Is there a risk that transgenic feral plants serve as reservoirs or conduits that might facilitate the movement of transg...

  13. Dynamics of predation on Lygus hesperus (Hemiptera: Miridae) in alfalfa trap cropped organic strawberry

    Science.gov (United States)

    Alfalfa (Medicago sativa L.) can be strategically planted as a trap crop for Lygus spp. in California’s organic strawberry fields. Alfalfa has been shown to attract both Lygus spp. and, in turn, a Lygus-specific parasitoid, Peristenus relictus (Ruthe). However, the impact of alfalfa trap-cropped st...

  14. Ants farm subterranean aphids mostly in single clone groups - an example of prudent husbandry for carbohydrates and proteins?

    Directory of Open Access Journals (Sweden)

    Ivens Aniek BF

    2012-07-01

    Full Text Available Abstract Background Mutualistic interactions are wide-spread but the mechanisms underlying their evolutionary stability and ecological dynamics remain poorly understood. Cultivation mutualisms in which hosts consume symbionts occur in phylogenetically diverse groups, but often have symbiont monocultures for each host. This is consistent with the prediction that symbionts should avoid coexistence with other strains so that host services continue to benefit relatives, but it is less clear whether hosts should always favor monocultures and what mechanisms they might have to manipulate symbiont diversity. Few mutualisms have been studied in sufficient genetic detail to address these issues, so we decided to characterize symbiont diversity in the complex mutualism between multiple root aphid species and Lasius flavus ants. After showing elsewhere that three of these aphid species have low dispersal and mostly if not exclusively asexual reproduction, we here investigate aphid diversity within and between ant nest mounds. Results The three focal species (Geoica utricularia, Forda marginata and Tetraneura ulmi had considerable clonal diversity at the population level. Yet more than half of the ant mounds contained just a single aphid species, a significantly higher percentage than expected from a random distribution. Over 60% of these single-species mounds had a single aphid clone, and clones tended to persist across subsequent years. Whenever multiple species/clones co-occurred in the same mound, they were spatially separated with more than 95% of the aphid chambers containing individuals of a single clone. Conclusions L. flavus “husbandry” is characterized by low aphid “livestock” diversity per colony, especially at the nest-chamber level, but it lacks the exclusive monocultures known from other cultivation mutualisms. The ants appear to eat most of the early instar aphids, so that adult aphids are unlikely to face limited phloem resources and

  15. N resource of grasses and N2-fixation of alfalfa in mono-culture and mixture

    International Nuclear Information System (INIS)

    Zhu Shuxiu

    1992-01-01

    The N behavior in alfalfa and gramineous forage grasses, tall fescue, siberian wild rye, wheat grass and awnless brome were studied in potting and pasture experiments in 1986-1988 by using 15 N isotope dilution technique. Comparison was made between the mixed culture and mono-culture. The % Ndff and %Ndfs of grasses were decreased by 14.19% and 20.76% respectively, while %Ndfa of alfalfa was increased by 20.22% in mixed culture as compared with mono-culture. The 15 N and soil N uptake data revealed that this enhancement was largely due to a lower competitive ability for soil N by alfalfa than by grass in mixed stands, causing the alfalfa to depend more on atmospheric N 2 fixation. 20.62%of N of grasses in mixed culture was from the N 2 -fixation by alfalfa, causing N level in root-sphere of alfalfa decreasing, which was considered to be one of the reasons that %Ndfa increased in mixed culture. N transfer may be carried out by the decomposition of roots and nodules of alfalfa plants

  16. Cucumber Plants Baited with Methyl Salicylate Accelerates Scymnus (Pullus) sodalis (Coleoptera: Coccinellidae) Visiting to Reduce Cotton Aphid (Hemiptera: Aphididae) Infestation.

    Science.gov (United States)

    Dong, Y J; Hwang, S Y

    2017-10-01

    The cotton aphid, Aphis gossypii (Glover) (Hemiptera: Aphididae), is a major pest of many crops worldwide and a major cucumber plant pest in Taiwan. Because cotton aphids rapidly develop insecticide resistance and because of the insecticide residue problem, a safe and sustainable method is required to replace conventional chemical control methods. Methyl salicylate (MeSA), a herbivore-induced plant volatile, has been shown to affect aphids' behavior and attract the natural enemies of aphids for reducing their population. Therefore, this study examined the direct effects of MeSA on cotton aphids' settling preference, population development, and attractiveness to natural enemies. The efficiency of using MeSA and the commercial insecticide pymetrozine for reducing the cotton aphid population in laboratory and outdoor cucumber plant pot was also examined. The results showed no difference in winged aphids' settling preference and population development between the MeSA and blank treatments. Cucumber plants infested with cotton aphids and baited with 0.1% or 10% MeSA contained significantly higher numbers of the natural enemy of cotton aphids, namely Scymnus (Pullus) sodalis (Weise) (Coleoptera: Coccinellidae), and MeSA-treated cucumber plants contained a lower number of aphids. Significantly lower cotton aphid numbers were found on cucumber plants within a 10-m range of MeSA application. In addition, fruit yield showed no difference between the MeSA and pymetrozine treatments. According to our findings, 0.1% MeSA application can replace insecticides as a cotton aphid control tool. However, large-scale experiments are necessary to confirm its efficiency and related conservation biological control strategies before further use. © The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  17. Evaluation for dinitrogen fixation of alfalfa in field based on δ15N value

    International Nuclear Information System (INIS)

    Yao Yunyin; Chen Ming; Zhang Xizhong

    1992-12-01

    The dinitrogen fixation rate of alfalfa was estimated grown in pot and field experiments. β values (isotope fraction factor) of 7 cultivars of alfalfa (Medicago sativa L.) and white clover (Trifolium repens L.) grown in N-free liquid culture medium were examined. Variations in the δ 15 N values of varieties of alfalfa at growing seasons and forage grasses grown under various conditions were measured. %Ndfa of alfalfa was estimated using the natural 15 N abundance method, 15 N isotope dilution method and total N difference, and their accuracy was compared

  18. Impact of fertilization and granular insecticides on the incidence of tobacco aphid, myzus persicae (sulz)

    International Nuclear Information System (INIS)

    Razaq, A.; Hussain, N.; Khalil, S.K.; Alamzeb

    1989-01-01

    Field studies were conducted on the control of tobacco aphid, Myzus persicase (Sulz) with four granular insecticides, viz, Furadan 3% G, Diazinon 5% g, Thiodan 5% g and Larsban 5% g, with and without NPK fertilization. The aphid population was significantly higher in the fertilized plots compared to the non-fertilized ones. All the four insecticides significantly reduced the aphids density compared to the check. Furada 3% gave best results for the control of this pest. (author)

  19. Modification of Cry4Aa toward Improved Toxin Processing in the Gut of the Pea Aphid, Acyrthosiphon pisum.

    Directory of Open Access Journals (Sweden)

    Michael A Rausch

    Full Text Available Aphids are sap-sucking insects (order: Hemiptera that cause extensive damage to a wide range of agricultural crops. Our goal was to optimize a naturally occurring insecticidal crystalline (Cry toxins produced by the soil-dwelling bacterium Bacillus thuringiensis for use against the pea aphid, Acyrthosiphon pisum. On the basis that activation of the Cry4Aa toxin is a rate-limiting factor contributing to the relatively low aphicidal activity of this toxin, we introduced cathepsin L and cathepsin B cleavage sites into Cry4Aa for rapid activation in the aphid gut environment. Incubation of modified Cry4Aa and aphid proteases in vitro demonstrated enhanced processing of the toxin into the active form for some of the modified constructs relative to non-modified Cry4Aa. Aphids fed artificial diet with toxin at a final concentration of 125 μg/ml showed enhanced mortality after two days for one of the four modified constructs. Although only modest toxin improvement was achieved by use of this strategy, such specific toxin modifications designed to overcome factors that limit aphid toxicity could be applied toward managing aphid populations via transgenic plant resistance.

  20. Establishment of Lipolexis oregmae (Hymenoptera: Aphidiidae) in a classical biological control program directed against the brown citrus aphid (Homoptera: Aphididae) in Florida

    International Nuclear Information System (INIS)

    Persad, A.B.; Hoy, M.A.; Ru Nguyen

    2007-01-01

    The parasitoid Lipolexis oregmae Gahan (introduced as L. scutellaris Mackauer) was imported from Guam, evaluated in quarantine, mass reared, and released into citrus groves in Florida in a classical biological control program directed against the brown citrus aphid, Toxoptera citricida Kirkaldy. Releases of 20,200, 12,100, and 1,260 adults of L. oregmae were made throughout Florida during 2000, 2001, and 2002, respectively. To determine if L. oregmae had successfully established, surveys were conducted throughout the state beginning in the summer of 2001 and continuing through the summer of 2003. Parasitism during 2001 and 2002 was evaluated by holding brown citrus aphids in the laboratory until parasitoid adults emerged. Lipolexis oregmae was found in 10 sites in 7 counties and 4 sites in 3 counties with parasitism rates ranging from 0.7 to 3.3% in 2001 and 2002, respectively. Laboratory tests indicated that high rates of mortality occurred if field-collected parasitized aphids were held in plastic bags, so a molecular assay was used that allowed immature L. oregmae to be detected within aphid hosts immediately after collection. The molecular assay was used in 2003 with the brown citrus aphids and with other aphid species collected from citrus, weeds, and vegetables near former release sites; immatures of L. oregmae were detected in black citrus aphids, cowpea aphids, spirea aphids, and melon aphids, as well as in the brown citrus aphid, in 4 of 8 counties sampled, with parasitism ranging from 2.0 to 12.9%, indicating that L. oregmae is established and widely distributed. Samples taken in Polk County during Oct 2005 indicated that L. oregmae has persisted. The ability of L. oregmae to parasitize other aphid species on citrus, and aphids on other host plants, enhances the ability of L. oregmae to persist when brown citrus aphid populations are low. (author) [es

  1. 76 FR 5780 - Determination of Regulated Status of Alfalfa Genetically Engineered for Tolerance to the...

    Science.gov (United States)

    2011-02-02

    ...] Determination of Regulated Status of Alfalfa Genetically Engineered for Tolerance to the Herbicide Glyphosate... decision and determination on the petition regarding the regulated status of alfalfa genetically engineered... regulated status of alfalfa genetically engineered for tolerance to the herbicide glyphosate based on an...

  2. Resistance of Four Canola Genotypes Against Cabbage Aphid Brevicoryne brassicae (L.

    Directory of Open Access Journals (Sweden)

    S.H. MousaviAnzabi

    2017-12-01

    Full Text Available Introduction: Canola (Brassica napus L. is one of the prominent oil seed plants in Iran. This plant has good agricultural and food nourishment properties, such as resistant to drought, cold and salinity stresses and low level of cholesterol. Cabbage waxy aphid Brevicorynebrassicae (L. is the most important and cosmopolitan pest of cruciferous crops. This aphid is reduced 9 to 77% grain yields and up to 11% oil content. Developing environmental-friendly methods, such as deploying insect-resistant varieties to pest control was advised by scientists. Resistant varieties decrease production costs and can be integrated with other pest control policies in IPM programs. In a greenhouse experiment plants of cabbage, cauliflower wassusceptible host plant and broccoli, turnip, rapeseed, showed resistance to cabbage aphid. With the aim of identifying the existence of resistance resources, a laboratory study was conducted to evaluate the effects of seven canola genotypes on biological parameters of cabbage aphid. Detected resistant variety could be used as a resistance source. Material and Methods: In order to resistancy evaluation of canola, genotypes contain “RGS”,“Hyola-308”,“Hyola-401” and “Sarigol” to cabbage aphid, two experiments was conducted under field and greenhouse conditions in Kahriz region of West Azerbaijan province in 2010.In this study infestation index and tolerance in Field conditions and antibiosis study in greenhouse conditions was evaluated.To study antibiosis, genotypes were planted in pots with 10 replications based on completely random design and cabbage aphid population intrinsic rate of increase (rm was calculated. As followed: (Lotka 1924: 1= other population parameters computed by Carey (1993 method. Field experiment contains10 replications wereperformed based on complete randomized blocks experimental designs that five of them were under natural infestation and five others, free of infestation (control. To

  3. Proteomic Identification of Differentially Expressed Proteins during Alfalfa (Medicago sativa L.) Flower Development.

    Science.gov (United States)

    Chen, Lingling; Chen, Quanzhu; Zhu, Yanqiao; Hou, Longyu; Mao, Peisheng

    2016-01-01

    Flower development, pollination, and fertilization are important stages in the sexual reproduction process of plants; they are also critical steps in the control of seed formation and development. During alfalfa ( Medicago sativa L.) seed production, some distinct phenomena such as a low seed setting ratio, serious flower falling, and seed abortion commonly occur. However, the causes of these phenomena are complicated and largely unknown. An understanding of the mechanisms that regulate alfalfa flowering is important in order to increase seed yield. Hence, proteomic technology was used to analyze changes in protein expression during the stages of alfalfa flower development. Flower samples were collected at pre-pollination (S1), pollination (S2), and the post-pollination senescence period (S3). Twenty-four differentially expressed proteins were successfully identified, including 17 down-regulated in pollinated flowers, one up-regulated in pollinated and senesced flowers, and six up-regulated in senesced flowers. The largest proportions of the identified proteins were involved in metabolism, signal transduction, defense response, oxidation reduction, cell death, and programmed cell death (PCD). Their expression profiles demonstrated that energy metabolism, carbohydrate metabolism, and amino acid metabolism provided the nutrient foundation for pollination in alfalfa. Furthermore, there were three proteins involved in multiple metabolic pathways: dual specificity kinase splA-like protein (kinase splALs), carbonic anhydrase, and NADPH: quinone oxidoreductase-like protein. Expression patterns of these proteins indicated that MAPK cascades regulated multiple processes, such as signal transduction, stress response, and cell death. PCD also played an important role in the alfalfa flower developmental process, and regulated both pollination and flower senescence. The current study sheds some light on protein expression profiles during alfalfa flower development and

  4. Alfalfa transgene dispersal and adventitious presence: understanding grower perception of risk

    Science.gov (United States)

    Recognizing the importance of coexistence, the alfalfa industry has developed a set of Best Management Practices (BMP) to maintain separation of GE and conventional production. But the success of BMP depends upon the degree that growers comply. Therefore we surveyed 530 alfalfa hay and seed producer...

  5. Complete genome sequence of a new enamovirus from Argentina infecting alfalfa plants showing dwarfism symptoms.

    Science.gov (United States)

    Bejerman, Nicolás; Giolitti, Fabián; Trucco, Verónica; de Breuil, Soledad; Dietzgen, Ralf G; Lenardon, Sergio

    2016-07-01

    Alfalfa dwarf disease, probably caused by synergistic interactions of mixed virus infections, is a major and emergent disease that threatens alfalfa production in Argentina. Deep sequencing of diseased alfalfa plant samples from the central region of Argentina resulted in the identification of a new virus genome resembling enamoviruses in sequence and genome structure. Phylogenetic analysis suggests that it is a new member of the genus Enamovirus, family Luteoviridae. The virus is tentatively named "alfalfa enamovirus 1" (AEV-1). The availability of the AEV-1 genome sequence will make it possible to assess the genetic variability of this virus and to construct an infectious clone to investigate its role in alfalfa dwarfism disease.

  6. Uptake of oxytetracycline and its phytotoxicity to alfalfa (Medicago sativa L.)

    International Nuclear Information System (INIS)

    Kong, W.D.; Zhu, Y.G.; Liang, Y.C.; Zhang, J.; Smith, F.A.; Yang, M.

    2007-01-01

    A series of experiments were conducted in a hydroponic system to investigate the uptake of oxytetracycline (OTC) and its toxicity to alfalfa (Medicago sativa L.). OTC inhibited alfalfa shoot and root growth by up to 61% and 85%, respectively. The kinetics of OTC uptake could be well described by Michaelis-Menten equation with V max of 2.25 μmol g -1 fresh weight h -1 , and K m of 0.036 mM. The uptake of OTC by alfalfa was strongly inhibited by the metabolic inhibitor, 2,4-DNP (2,4-dinitrophenol), at pH 3.5 and 6.0, but not by the aquaporin competitors, glycerol and Ag + . OTC uptake, however, was significantly inhibited by Hg 2+ , suggesting that the inhibition of influx was due to general cellular stress rather than the specific action of Hg 2+ on aquaporins. Results from the present study suggested that OTC uptake into alfalfa is an energy-dependent process. - Plant uptake of antibiotic oxytetracycline is energy-dependent

  7. Enhancing pollination by attracting & retaining leaf cutting bees (Megachile rotundata) in alfalfa seed production fields

    Science.gov (United States)

    The alfalfa leafcutting bee, Megachile rotundata (F.), has become an important managed pollinator of alfalfa, Medicago sativa L. One problem when using alfalfa leafcutting bees as managed pollinator, is the dispersal of many females upon release, even when adequate nesting sites are present. While d...

  8. Bacterial symbionts, Buchnera, and starvation on wing dimorphism in English grain aphid, Sitobion avenae (F. (Homoptera: Aphididae

    Directory of Open Access Journals (Sweden)

    Fangmei eZhang

    2015-05-01

    Full Text Available Wing dimorphism in aphids can be affected by multiple cues, including both biotic (nutrition, crowding, interspecific interactions, the presence of natural enemies, maternal and transgenerational effects, and alarm pheromone and abiotic factors (temperature, humidity, and photoperiod. The majority of the phloem-feeding aphids carry Buchnera, an obligate symbiotic proteobacteria. Buchnera has a highly reduced genome size, but encode key enzymes in the tryptophan biosynthetic pathway and is crucial for nutritional balance, development and reproduction in aphids. In this study, we investigated the impact of two nutritional-based biotic factors, symbionts and starvation, on the wing dimorphism in the English grain aphid, Sitobion avenae, a devastating insect pest of cereal crops (e.g., wheat worldwide. Elimination of Buchnera using the antibiotic rifampicin significantly reduced the formation of winged morphs, body mass and fecundity in S. avenae. Furthermore, the absence of this primary endosymbiont may disrupt the nutrient acquisition in aphids and alter transgenerational phenotypic expression. Similarly, both survival rate and the formation of winged morphs were substantially reduced after neonatal (< 24h old offspring were starved for a period of time. The combined results shed light on the impact of two nutritional-based biotic factors on the phenotypic plasticity in aphids. A better understanding of the wing dimorphism in aphids will provide the theoretical basis for the prediction and integrated management of these phloem-feeding insect pests.

  9. Complete nucleotide sequence of Alfalfa mosaic virus isolated from alfalfa (Medicago sativa L.) in Argentina.

    Science.gov (United States)

    Trucco, Verónica; de Breuil, Soledad; Bejerman, Nicolás; Lenardon, Sergio; Giolitti, Fabián

    2014-06-01

    The complete nucleotide sequence of an Alfalfa mosaic virus (AMV) isolate infecting alfalfa (Medicago sativa L.) in Argentina, AMV-Arg, was determined. The virus genome has the typical organization described for AMV, and comprises 3,643, 2,593, and 2,038 nucleotides for RNA1, 2 and 3, respectively. The whole genome sequence and each encoding region were compared with those of other four isolates that have been completely sequenced from China, Italy, Spain and USA. The nucleotide identity percentages ranged from 95.9 to 99.1 % for the three RNAs and from 93.7 to 99 % for the protein 1 (P1), protein 2 (P2), movement protein and coat protein (CP) encoding regions, whereas the amino acid identity percentages of these proteins ranged from 93.4 to 99.5 %, the lowest value corresponding to P2. CP sequences of AMV-Arg were compared with those of other 25 available isolates, and the phylogenetic analysis based on the CP gene was carried out. The highest percentage of nucleotide sequence identity of the CP gene was 98.3 % with a Chinese isolate and 98.6 % at the amino acid level with four isolates, two from Italy, one from Brazil and the remaining one from China. The phylogenetic analysis showed that AMV-Arg is closely related to subgroup I of AMV isolates. To our knowledge, this is the first report of a complete nucleotide sequence of AMV from South America and the first worldwide report of complete nucleotide sequence of AMV isolated from alfalfa as natural host.

  10. The Endosymbiont Arsenophonus Is Widespread in Soybean Aphid, Aphis glycines, but Does Not Provide Protection from Parasitoids or a Fungal Pathogen

    Science.gov (United States)

    Wulff, Jason A.; Buckman, Karrie A.; Wu, Kongming; Heimpel, George E.; White, Jennifer A.

    2013-01-01

    Aphids commonly harbor bacterial facultative symbionts that have a variety of effects upon their aphid hosts, including defense against hymenopteran parasitoids and fungal pathogens. The soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), is infected with the symbiont Arsenophonus sp., which has an unknown role in its aphid host. Our research goals were to document the infection frequency and diversity of the symbiont in field-collected soybean aphids, and to determine whether Arsenophonus is defending soybean aphid against natural enemies. We performed diagnostic PCR and sequenced four Arsenophonus genes in soybean aphids from their native and introduced range to estimate infection frequency and genetic diversity, and found that Arsenophonus infection is highly prevalent and genetically uniform. To evaluate the defensive role of Arsenophonus, we cured two aphid genotypes of their natural Arsenophonus infection through ampicillin microinjection, resulting in infected and uninfected isolines within the same genetic background. These isolines were subjected to parasitoid assays using a recently introduced biological control agent, Binodoxys communis [Braconidae], a naturally recruited parasitoid, Aphelinus certus [Aphelinidae], and a commercially available biological control agent, Aphidius colemani [Braconidae]. We also assayed the effect of the common aphid fungal pathogen, Pandora neoaphidis (Remaudiere & Hennebert) Humber (Entomophthorales: Entomophthoraceae), on the same aphid isolines. We did not find differences in successful parasitism for any of the parasitoid species, nor did we find differences in P. neoaphidis infection between our treatments. Our conclusion is that Arsenophonus does not defend its soybean aphid host against these major parasitoid and fungal natural enemies. PMID:23614027

  11. Evidence for an Invasive Aphid “Superclone”: Extremely Low Genetic Diversity in Oleander Aphid (Aphis nerii) Populations in the Southern United States

    Science.gov (United States)

    Harrison, John Scott; Mondor, Edward B.

    2011-01-01

    Background The importance of genetic diversity in successful biological invasions is unclear. In animals, but not necessarily plants, increased genetic diversity is generally associated with successful colonization and establishment of novel habitats. The Oleander aphid, Aphis nerii, though native to the Mediterranean region, is an invasive pest species throughout much of the world. Feeding primarily on Oleander (Nerium oleander) and Milkweed (Asclepias spp.) under natural conditions, these plants are unlikely to support aphid populations year round in the southern US. The objective of this study was to describe the genetic variation within and among US populations of A. nerii, during extinction/recolonization events, to better understand the population ecology of this invasive species. Methodology/Principal Findings We used five microsatellite markers to assess genetic diversity over a two year period within and among three aphid populations separated by small (100 km) and large (3,700 km) geographic distances on two host plant species. Here we provide evidence for A. nerii “superclones”. Genotypic variation was absent in all populations (i.e., each population consisted of a single multilocus genotype (MLG) or “clone”) and the genetic composition of only one population completely changed across years. There was no evidence of sexual reproduction or host races on different plant species. Conclusions/Significance Aphis nerii is a well established invasive species despite having extremely low genetic diversity. As this aphid appears to be obligatorily asexual, it may share more similarities with clonally reproducing invasive plants, than with other animals. Patterns of temporal and geographic genetic variation, viewed in the context of its population dynamics, have important implications for the management of invasive pests and the evolutionary biology of asexual species. PMID:21408073

  12. Induced resistant mutations in alfalfa and broad bean against rust, leaf spot and wilh diseases by Gamma rays and ethylmethanesulfonate

    International Nuclear Information System (INIS)

    1988-01-01

    In alfalfa after gamma irradiation with 50,100, and 150 krads, 38 rust resistant plants have been selected throughout a screening programme. During four months, cuttings were obtained from these plants individually. Results revealed that 20 plants were remar-kably surpassed the origin in the total fresh weight and in the average weight of each cutting. In broad bean, following gamma irradiation and EMS in two cuitivars for induction of wilt resistance. Seeds of these plants were sown in artificially infested soil . During the growing season, all susceptible plants were removed and at epidemic form of wilt disease

  13. Ethanol production from alfalfa fiber fractions by saccharification and fermentation

    Energy Technology Data Exchange (ETDEWEB)

    Sreenath, H.K. [University of Wisconsin, Madison, WI (United States). Dept. of Biological Systems Engineering; USDA Forest Service, Madison, WI (United States). Forest Products Lab.; Koegel, R.G. [US Department of Agriculture, Madison, WI (United States). Dairy Forage Research Center; Moldes, A.B. [USDA Forest Service, Madison, WI (United States). Forest Products Lab.; Universidade de Vigo, Ourense (Spain); Jeffries, T.W. [USDA Forest Service, Madison, WI (United States). Forest Products Lab.; Straub, R.J. [University of Wisconsin, Madison, WI (United States). Dept. of Biological Systems Engineering

    2001-07-01

    This work describes ethanol production from alfalfa fiber using separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) with and without liquid hot water (LHW) pretreatment. Candida shehatae FPL-702 produced 5 and 6.4 g/l ethanol with a yield of 0.25 and 0.16 g ethanol/g sugar respectively by SHF and SSF from alfalfa fiber without pretreatment. With LHW pretreatment using SSF, C. shehatae FPL-702 produced 18.0 g/l ethanol, a yield of 0.45 g ethanol/g sugar from cellulosic solids or 'raffinate'. Using SHF, it produced 9.6 g/l ethanol, a yield of 0.47 g ethanol/g sugar from raffinate. However, the soluble extract fraction containing hemicelluloses was poorly fermented in both SHF and SSF due to the presence of inhibitors. Addition of dilute acid during LHW pretreatment of alfalfa fiber resulted in fractions that were poorly saccharified and fermented. These results show that unpretreated alfalfa fiber produced a lower ethanol yield. Although LHW pretreatment can increase ethanol production from raffinate fiber fractions, it does not increase production from the hemicellulosic and pectin fractions. (author)

  14. Laboratory and semi-field evaluation of Beauveria bassiana (Ascomycota: Hypocreales) against the lettuce aphid, Nasonovia ribisnigri (Hemiptera: Aphididae)

    DEFF Research Database (Denmark)

    Shrestha, Govinda; Enkegaard, Annie; Steenberg, Tove

    2015-01-01

    The lettuce aphid, Nasonovia ribisnigri (Mosley), is an economically important pest of lettuce worldwide. The entomopathogenic fungus Beauveria bassiana strain GHA has recently been reported as a potential biocontrol candidate for use against the lettuce aphid. This study provides information...... on the mortality inflicted by B. bassiana when applied against different life stages of the lettuce aphid under laboratory conditions and how fungus infection affects the aphid fecundity. In addition, temporal changes in persistence of fungus inoculum applied to foliage of young lettuce plants under semi......-field conditions was analysed. Immature life stages were generally the least susceptible to fungal infection and the susceptibility of all stages was dose-dependent, with the highest mortality occurring at the highest dose. B. bassiana significantly affected the rate of nymph production by the lettuce aphid...

  15. GAS, STARS, AND STAR FORMATION IN ALFALFA DWARF GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Huang Shan; Haynes, Martha P.; Giovanelli, Riccardo [Center for Radiophysics and Space Research, Space Sciences Building, Cornell University, Ithaca, NY 14853 (United States); Brinchmann, Jarle [Sterrewacht Leiden, Leiden University, NL-2300 RA Leiden (Netherlands); Stierwalt, Sabrina [Spitzer Science Center, California Institute of Technology, 1200 E. California Blvd., Pasadena, CA 91125 (United States); Neff, Susan G., E-mail: shan@astro.cornell.edu, E-mail: haynes@astro.cornell.edu, E-mail: riccardo@astro.cornell.edu, E-mail: jarle@strw.leidenuniv.nl, E-mail: sabrina@ipac.caltech.edu, E-mail: susan.g.neff@nasa.gov [NASA GSFC, Code 665, Observational Cosmology Lab, Greenbelt, MD 20771 (United States)

    2012-06-15

    We examine the global properties of the stellar and H I components of 229 low H I mass dwarf galaxies extracted from the ALFALFA survey, including a complete sample of 176 galaxies with H I masses <10{sup 7.7} M{sub Sun} and H I line widths <80 km s{sup -1}. Sloan Digital Sky Survey (SDSS) data are combined with photometric properties derived from Galaxy Evolution Explorer to derive stellar masses (M{sub *}) and star formation rates (SFRs) by fitting their UV-optical spectral energy distributions (SEDs). In optical images, many of the ALFALFA dwarfs are faint and of low surface brightness; only 56% of those within the SDSS footprint have a counterpart in the SDSS spectroscopic survey. A large fraction of the dwarfs have high specific star formation rates (SSFRs), and estimates of their SFRs and M{sub *} obtained by SED fitting are systematically smaller than ones derived via standard formulae assuming a constant SFR. The increased dispersion of the SSFR distribution at M{sub *} {approx}< 10{sup 8} M{sub Sun} is driven by a set of dwarf galaxies that have low gas fractions and SSFRs; some of these are dE/dSphs in the Virgo Cluster. The imposition of an upper H I mass limit yields the selection of a sample with lower gas fractions for their M{sub *} than found for the overall ALFALFA population. Many of the ALFALFA dwarfs, particularly the Virgo members, have H I depletion timescales shorter than a Hubble time. An examination of the dwarf galaxies within the full ALFALFA population in the context of global star formation (SF) laws is consistent with the general assumptions that gas-rich galaxies have lower SF efficiencies than do optically selected populations and that H I disks are more extended than stellar ones.

  16. GAS, STARS, AND STAR FORMATION IN ALFALFA DWARF GALAXIES

    International Nuclear Information System (INIS)

    Huang Shan; Haynes, Martha P.; Giovanelli, Riccardo; Brinchmann, Jarle; Stierwalt, Sabrina; Neff, Susan G.

    2012-01-01

    We examine the global properties of the stellar and H I components of 229 low H I mass dwarf galaxies extracted from the ALFALFA survey, including a complete sample of 176 galaxies with H I masses 7.7 M ☉ and H I line widths –1 . Sloan Digital Sky Survey (SDSS) data are combined with photometric properties derived from Galaxy Evolution Explorer to derive stellar masses (M * ) and star formation rates (SFRs) by fitting their UV-optical spectral energy distributions (SEDs). In optical images, many of the ALFALFA dwarfs are faint and of low surface brightness; only 56% of those within the SDSS footprint have a counterpart in the SDSS spectroscopic survey. A large fraction of the dwarfs have high specific star formation rates (SSFRs), and estimates of their SFRs and M * obtained by SED fitting are systematically smaller than ones derived via standard formulae assuming a constant SFR. The increased dispersion of the SSFR distribution at M * ∼ 8 M ☉ is driven by a set of dwarf galaxies that have low gas fractions and SSFRs; some of these are dE/dSphs in the Virgo Cluster. The imposition of an upper H I mass limit yields the selection of a sample with lower gas fractions for their M * than found for the overall ALFALFA population. Many of the ALFALFA dwarfs, particularly the Virgo members, have H I depletion timescales shorter than a Hubble time. An examination of the dwarf galaxies within the full ALFALFA population in the context of global star formation (SF) laws is consistent with the general assumptions that gas-rich galaxies have lower SF efficiencies than do optically selected populations and that H I disks are more extended than stellar ones.

  17. Seasonal phenology and species composition of the aphid fauna in a northern crop production area.

    Directory of Open Access Journals (Sweden)

    Sascha M Kirchner

    Full Text Available BACKGROUND: The species diversity of aphids and seasonal timing of their flight activity can have significant impacts on crop production, as aphid species differ in their ability to transmit plant viruses and flight timing affects virus epidemiology. The aim of the study was to characterise the species composition and phenology of aphid fauna in Finland in one of the northernmost intensive crop production areas of the world (latitude 64°. METHODOLOGY/PRINCIPAL FINDINGS: Flight activity was monitored in four growing seasons (2007-010 using yellow pan traps (YPTs placed in 4-8 seed potato fields and a Rothamsted suction trap. A total of 58,528 winged aphids were obtained, identified to 83 taxa based on morphology, and 34 species were additionally characterised by DNA barcoding. Seasonal flight activity patterns analysed based on YPT catch fell into three main phenology clusters. Monoecious taxa showed early or middle-season flight activity and belonged to species living on shrubs/trees or herbaceous plants, respectively. Heteroecious taxa occurred over the entire potato growing season (ca. 90 days. Abundance of aphids followed a clear 3-year cycle based on suction trap data covering a decade. Rhopalosiphum padi occurring at the end of the potato growing season was the most abundant species. The flight activity of Aphis fabae, the main vector of Potato virus Y in the region, and Aphis gossypii peaked in the beginning of potato growing season. CONCLUSIONS/SIGNIFICANCE: Detailed information was obtained on phenology of a large number aphid species, of which many are agriculturally important pests acting as vectors of plant viruses. Aphis gossypii is known as a pest in greenhouses, but our study shows that it occurs also in the field, even far in the north. The novel information on aphid phenology and ecology has wide implications for prospective pest management, particularly in light of climate change.

  18. The Polerovirus Minor Capsid Protein Determines Vector Specificity and Intestinal Tropism in the Aphid

    Science.gov (United States)

    Brault, Véronique; Périgon, Sophie; Reinbold, Catherine; Erdinger, Monique; Scheidecker, Danièle; Herrbach, Etienne; Richards, Ken; Ziegler-Graff, Véronique

    2005-01-01

    Aphid transmission of poleroviruses is highly specific, but the viral determinants governing this specificity are unknown. We used a gene exchange strategy between two poleroviruses with different vectors, Beet western yellows virus (BWYV) and Cucurbit aphid-borne yellows virus (CABYV), to analyze the role of the major and minor capsid proteins in vector specificity. Virus recombinants obtained by exchanging the sequence of the readthrough domain (RTD) between the two viruses replicated in plant protoplasts and in whole plants. The hybrid readthrough protein of chimeric viruses was incorporated into virions. Aphid transmission experiments using infected plants or purified virions revealed that vector specificity is driven by the nature of the RTD. BWYV and CABYV have specific intestinal sites in the vectors for endocytosis: the midgut for BWYV and both midgut and hindgut for CABYV. Localization of hybrid virions in aphids by transmission electron microscopy revealed that gut tropism is also determined by the viral origin of the RTD. PMID:16014930

  19. Effects of additive application upon ad libitum intake, in vivo digestibility and nitrogen balance of alfalfa haylage

    Directory of Open Access Journals (Sweden)

    Mladen Knežević

    2009-09-01

    Full Text Available The research objective was to determine the effect of the additive Sill-All application on ad libitum intake, in vivo digestibility and nitrogen balance of alfalfa haylage. About 40 % alfalfa plants was ensiled at the phonological flowering stage into plastic foil-wrapped bales without or with additive (2 L t-1 plant mass. No statistically significant differences were found between alfalfa ensiled without additive and alfalfa ensiled with additive for the content of dry matter (DM (632 g and 631 g DM kg-1 fresh sample, respectively. Alfalfa ensiled without additive contained 921 g organic matter (OM kg-1 DM, which was significantly higher (P<0.001 compared to alfalfa ensiled with additive (902 g OM kg-1 DM. Alfalfa ensiled without additive contained 141 g crude proteins (CP kg-1 DM, which was significantly higher (P<0.001 compared to alfalfa ensiled with additive (139 g CP kg-1 DM. Alfalfa ensiled with additive contained significantly less acid detergent fibers (ADF (P<0.001 compared to alfalfa ensiled without additive (445 g kg-1 DM and 456 g kg-1 DM, respectively and had a lower pH value (P<0.001 (5.29 and 5.56, respectively. No statistically significant differences were found between the studied feeding treatments for ad libitum intake of fresh ration and DM ration, for the measured parameters of digestibility and N balance. It was concluded that addition of the additive to alfalfa haylage led to significant changes in chemical composition; however, changes in chemical composition had no impact on measured biological parameters (ad libitum intake, in vivo digestibility and nitrogen balance.

  20. The price of protection: a defensive endosymbiont impairs nymph growth in the bird cherry-oat aphid, Rhopalosiphum padi.

    Science.gov (United States)

    Leybourne, Daniel J; Bos, Jorunn I B; Valentine, Tracy A; Karley, Alison J

    2018-05-24

    Bacterial endosymbionts have enabled aphids to adapt to a range of stressors, but their effects in many aphid species remain to be established. The bird cherry-oat aphid, Rhopalosiphum padi (Linnaeus), is an important pest of cereals worldwide and has been reported to form symbiotic associations with Serratia symbiotica and Sitobion miscanthi L-type Symbiont endobacteria, although the resulting aphid phenotype has not been described. This study presents the first report of R. padi infection with the facultative bacterial endosymbiont Hamiltonella defensa. Individuals of R. padi were sampled from populations in Eastern Scotland, UK, and shown to represent seven R. padi genotypes based on the size of polymorphic microsatellite markers; two of these genotypes harboured H. defensa. In parasitism assays, survival of H. defensa-infected nymphs following attack by the parasitoid wasp Aphidius colemani (Viereck) was five-fold higher than for uninfected nymphs. Aphid genotype was a major determinant of aphid performance on two Hordeum species, a modern cultivar of barley H. vulgaris and a wild relative H. spontaneum, although aphids infected with H. defensa showed 16% lower nymph mass gain on the partially-resistant wild relative compared with uninfected individuals. These findings suggest that deploying resistance traits in barley will favour the fittest R. padi genotypes, but symbiont-infected individuals will be favoured when parasitoids are abundant, although these aphids will not achieve optimal performance on a poor quality host plant. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

  1. All 37 Mitochondrial Genes of Aphid Aphis craccivora Obtained from Transcriptome Sequencing: Implications for the Evolution of Aphids.

    Directory of Open Access Journals (Sweden)

    Nan Song

    Full Text Available The availability of mitochondrial genome data for Aphididae, one of the economically important insect pest families, in public databases is limited. The advent of next generation sequencing technology provides the potential to generate mitochondrial genome data for many species timely and cost-effectively. In this report, we used transcriptome sequencing technology to determine all the 37 mitochondrial genes of the cowpea aphid, Aphis craccivora. This method avoids the necessity of finding suitable primers for long PCRs or primer-walking amplicons, and is proved to be effective in obtaining the whole set of mitochondrial gene data for insects with difficulty in sequencing mitochondrial genome by PCR-based strategies. Phylogenetic analyses of aphid mitochondrial genome data show clustering based on tribe level, and strongly support the monophyly of the family Aphididae. Within the monophyletic Aphidini, three samples from Aphis grouped together. In another major clade of Aphididae, Pterocomma pilosum was recovered as a potential sister-group of Cavariella salicicola, as part of Macrosiphini.

  2. Bacterial stem blight of alfalfa: A disease that increases frost damage

    Science.gov (United States)

    Alfalfa producers count on the first harvest in late spring to deliver the highest tonnage and best quality of forage of the year. A late frost can significantly reduce both yield and quality. Losses are due not only to the physical damage from freezing of the alfalfa stem and leaves but also from d...

  3. Expression profiling of selected glutathione transferase genes in Zea mays (L.) seedlings infested with cereal aphids.

    Science.gov (United States)

    Sytykiewicz, Hubert; Chrzanowski, Grzegorz; Czerniewicz, Paweł; Sprawka, Iwona; Łukasik, Iwona; Goławska, Sylwia; Sempruch, Cezary

    2014-01-01

    The purpose of this report was to evaluate the expression patterns of selected glutathione transferase genes (gst1, gst18, gst23 and gst24) in the tissues of two maize (Zea mays L.) varieties (relatively resistant Ambrozja and susceptible Tasty Sweet) that were colonized with oligophagous bird cherry-oat aphid (Rhopalosiphum padi L.) or monophagous grain aphid (Sitobion avenae L.). Simultaneously, insect-triggered generation of superoxide anion radicals (O2•-) in infested Z. mays plants was monitored. Quantified parameters were measured at 1, 2, 4, 8, 24, 48 and 72 h post-initial aphid infestation (hpi) in relation to the non-infested control seedlings. Significant increases in gst transcript amounts were recorded in aphid-stressed plants in comparison to the control seedlings. Maximal enhancement in the expression of the gst genes in aphid-attacked maize plants was found at 8 hpi (gst23) or 24 hpi (gst1, gst18 and gst24) compared to the control. Investigated Z. mays cultivars formed excessive superoxide anion radicals in response to insect treatments, and the highest overproduction of O2•- was noted 4 or 8 h after infestation, depending on the aphid treatment and maize genotype. Importantly, the Ambrozja variety could be characterized as having more profound increments in the levels of gst transcript abundance and O2•- generation in comparison with the Tasty Sweet genotype.

  4. Effects of dietary alfalfa inclusion on Salmonella typhimurium populations in growing layer chicks.

    Science.gov (United States)

    Escarcha, Jacquelyn F; Callaway, Todd R; Byrd, J Allen; Miller, Dan N; Edrington, Tom S; Anderson, Robin C; Nisbet, David J

    2012-10-01

    Reducing Salmonella in poultry has been a paramount goal of the poultry industry in order to improve food safety. Inclusion of high-fiber fermentable feedstuffs in chicken diets has been shown to reduce the incidence of Salmonella colonization in laying hens, but no work has been performed in growing birds. Therefore, the present study was designed to quantify differences in artificially inoculated cecal Salmonella Typhimurium populations in growing layer chicks (n = 60 in each of two replications) fed 0%, 25%, and 50% of their diet (w/w) replaced with alfalfa meal from day (d) 7 to d14 after hatch. Alfalfa supplementation reduced cecal populations of Salmonella by 0.95 and 1.25 log10 colony-forming unit per gram in the 25% and 50% alfalfa groups compared to controls. Alfalfa feeding reduced (p < 0.05) the number of cecal- and crop-positive birds compared to controls. Increasing levels of alfalfa increased (p < 0.05) total volatile fatty acids (VFA) and the proportion of acetate in the cecum. Surprisingly, alfalfa inclusion did not negatively impact average daily gain (ADG) in birds over the 7-d feeding period. Alfalfa inclusion at 50% of the diet increased (p < 0.05) the number of bacterial genera detected in the cecum compared to controls, and also altered proportions of the microbial population by reducing Ruminococcus and increasing Clostridia populations. Results support the idea that providing a fermentable substrate can increase gastrointestinal VFA production and bacterial diversity which in turn can reduce colonization by Salmonella via natural competitive barriers. However, further studies are obviously needed to more fully understand the impact of changes made in diet or management procedures on poultry production.

  5. Erwinia iniecta sp. nov., isolated from Russian wheat aphid (Diuraphis noxia).

    Science.gov (United States)

    Campillo, Tony; Luna, Emily; Portier, Perrine; Fischer-Le Saux, Marion; Lapitan, Nora; Tisserat, Ned A; Leach, Jan E

    2015-10-01

    Short, Gram-negative-staining, rod-shaped bacteria were isolated from crushed bodies of Russian wheat aphid [Diuraphis noxia (Kurdjumov)] and artificial diets after Russian wheat aphid feeding. Based on multilocus sequence analysis involving the 16S rRNA, atpD, infB, gyrB and rpoB genes, these bacterial isolates constitute a novel clade in the genus Erwinia, and were most closely related to Erwinia toletana. Representative distinct strains within this clade were used for comparisons with related species of Erwinia. Phenotypic comparisons using four distinct strains and average nucleotide identity (ANI) measurements using two distinct draft genomes revealed that these strains form a novel species within the genus Erwinia. The name Erwinia iniecta sp. nov. is proposed, and strain B120T ( = CFBP 8182T = NCCB 100485T) was designated the type strain. Erwinia iniecta sp. nov. was not pathogenic to plants. However, virulence to the Russian wheat aphid was observed.

  6. Uptake of oxytetracycline and its phytotoxicity to alfalfa (Medicago sativa L.)

    Energy Technology Data Exchange (ETDEWEB)

    Kong, W D [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Zhu, Y G [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Liang, Y C [Ministry of Agriculture Key Laboratory of Plant Nutrition and Nutrient Cycling, Institute of Soils and Fertilizers, Chinese Academy of Agricultural Sciences, Beijing 100081 (China); Zhang, J [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China); Smith, F A [Soil and Land Systems, School of Earth and Environmental Sciences, University of Adelaide, DP 636, Adelaide, SA 5005 (Australia); Yang, M [Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085 (China)

    2007-05-15

    A series of experiments were conducted in a hydroponic system to investigate the uptake of oxytetracycline (OTC) and its toxicity to alfalfa (Medicago sativa L.). OTC inhibited alfalfa shoot and root growth by up to 61% and 85%, respectively. The kinetics of OTC uptake could be well described by Michaelis-Menten equation with V {sub max} of 2.25 {mu}mol g{sup -1} fresh weight h{sup -1}, and K {sub m} of 0.036 mM. The uptake of OTC by alfalfa was strongly inhibited by the metabolic inhibitor, 2,4-DNP (2,4-dinitrophenol), at pH 3.5 and 6.0, but not by the aquaporin competitors, glycerol and Ag{sup +}. OTC uptake, however, was significantly inhibited by Hg{sup 2+}, suggesting that the inhibition of influx was due to general cellular stress rather than the specific action of Hg{sup 2+} on aquaporins. Results from the present study suggested that OTC uptake into alfalfa is an energy-dependent process. - Plant uptake of antibiotic oxytetracycline is energy-dependent.

  7. Proteomic identification of differentially expressed proteins during alfalfa (Medicago sativa L. flower development

    Directory of Open Access Journals (Sweden)

    Lingling Chen

    2016-10-01

    Full Text Available Flower development, pollination, and fertilization are important stages in the sexual reproduction process of plants; they are also critical steps in the control of seed formation and development. During alfalfa (Medicago sativa L. seed production, some distinct phenomena such as a low seed setting ratio, serious flower falling, and seed abortion commonly occur. However, the causes of these phenomena are complicated and largely unknown. An understanding of the mechanisms that regulate alfalfa flowering is important in order to increase seed yield. Hence, proteomic technology was used to analyze changes in protein expression during the stages of alfalfa flower development. Flower samples were collected at pre-pollination (S1, pollination (S2, and the post-pollination senescence period (S3. Twenty-four differentially expressed proteins were successfully identified, including 17 down-regulated in pollinated flowers, one up-regulated in pollinated and senesced flowers, and six up-regulated in senesced flowers. The largest proportions of the identified proteins were involved in metabolism, signal transduction, defense response, oxidation reduction, cell death, and programmed cell death (PCD. Their expression profiles demonstrated that energy metabolism, carbohydrate metabolism, and amino acid metabolism provided the nutrient foundation for pollination in alfalfa. Furthermore, there were three proteins involved in multiple metabolic pathways: dual specificity kinase splA-like protein (kinase splALs, carbonic anhydrase (CA, and NADPH: quinone oxidoreductase-like protein (NQOLs. Expression patterns of these proteins indicated that MAPK cascades regulated multiple processes, such as signal transduction, stress response, and cell death. PCD also played an important role in the alfalfa flower developmental process, and regulated both pollination and flower senescence. The current study sheds some light on protein expression profiles during alfalfa flower

  8. Dynamic Maize Responses to Aphid Feeding Are Revealed by a Time Series of Transcriptomic and Metabolomic Assays1[OPEN

    Science.gov (United States)

    Tzin, Vered; Fernandez-Pozo, Noe; Richter, Annett; Schmelz, Eric A.; Schoettner, Matthias; Schäfer, Martin; Ahern, Kevin R.; Meihls, Lisa N.; Kaur, Harleen; Huffaker, Alisa; Mori, Naoki; Degenhardt, Joerg; Mueller, Lukas A.; Jander, Georg

    2015-01-01

    As a response to insect attack, maize (Zea mays) has inducible defenses that involve large changes in gene expression and metabolism. Piercing/sucking insects such as corn leaf aphid (Rhopalosiphum maidis) cause direct damage by acquiring phloem nutrients as well as indirect damage through the transmission of plant viruses. To elucidate the metabolic processes and gene expression changes involved in maize responses to aphid attack, leaves of inbred line B73 were infested with corn leaf aphids for 2 to 96 h. Analysis of infested maize leaves showed two distinct response phases, with the most significant transcriptional and metabolic changes occurring in the first few hours after the initiation of aphid feeding. After 4 d, both gene expression and metabolite profiles of aphid-infested maize reverted to being more similar to those of control plants. Although there was a predominant effect of salicylic acid regulation, gene expression changes also indicated prolonged induction of oxylipins, although not necessarily jasmonic acid, in aphid-infested maize. The role of specific metabolic pathways was confirmed using Dissociator transposon insertions in maize inbred line W22. Mutations in three benzoxazinoid biosynthesis genes, Bx1, Bx2, and Bx6, increased aphid reproduction. In contrast, progeny production was greatly decreased by a transposon insertion in the single W22 homolog of the previously uncharacterized B73 terpene synthases TPS2 and TPS3. Together, these results show that maize leaves shift to implementation of physical and chemical defenses within hours after the initiation of aphid feeding and that the production of specific metabolites can have major effects in maize-aphid interactions. PMID:26378100

  9. A first report and complete genome sequence of alfalfa enamovirus from Sudan

    Science.gov (United States)

    A full genome sequence of a viral pathogen, provisionally named alfalfa enamovirus 2 (AEV-2), was reconstructed from short reads obtained by Illumina RNA sequencing of alfalfa sample originating from Sudan. Ambiguous nucleotides in the resultant consensus assembly and identity of the predicted virus...

  10. The importance of potassium in resistance to crown rot disease in alfalfa

    Science.gov (United States)

    Nitrogen, phosphate, and potassium (potash, K2O) are the three most important nutrients in alfalfa growth and development. Nitrogen fertilization is not required because alfalfa has a high rate of biological nitrogen fixation. Phosphorus and potassium are frequently applied as fertilizer, but potass...

  11. Forage accumulation and nutritive value of reduced lignin and reference alfalfa cultivars

    Science.gov (United States)

    Reduced lignin alfalfa (Medicago sativa L.) cultivars have the potential to increase the feeding value of alfalfa for livestock by improving the forage fiber digestibility and to increase harvest management flexibility. The objectives were to compare the yield and forage nutritive value of reduced ...

  12. Up-regulation of abscisic acid signaling pathway facilitates aphid xylem absorption and osmoregulation under drought stress.

    Science.gov (United States)

    Guo, Huijuan; Sun, Yucheng; Peng, Xinhong; Wang, Qinyang; Harris, Marvin; Ge, Feng

    2016-02-01

    The activation of the abscisic acid (ABA) signaling pathway reduces water loss from plants challenged by drought stress. The effect of drought-induced ABA signaling on the defense and nutrition allocation of plants is largely unknown. We postulated that these changes can affect herbivorous insects. We studied the effects of drought on different feeding stages of pea aphids in the wild-type A17 of Medicago truncatula and ABA signaling pathway mutant sta-1. We examined the impact of drought on plant water status, induced plant defense signaling via the abscisic acid (ABA), jasmonic acid (JA), and salicylic acid (SA) pathways, and on the host nutritional quality in terms of leaf free amino acid content. During the penetration phase of aphid feeding, drought decreased epidermis/mesophyll resistance but increased mesophyll/phloem resistance of A17 but not sta-1 plants. Quantification of transcripts associated with ABA, JA and SA signaling indicated that the drought-induced up-regulation of ABA signaling decreased the SA-dependent defense but increased the JA-dependent defense in A17 plants. During the phloem-feeding phase, drought had little effect on the amino acid concentrations and the associated aphid phloem-feeding parameters in both plant genotypes. In the xylem absorption stage, drought decreased xylem absorption time of aphids in both genotypes because of decreased water potential. Nevertheless, the activation of the ABA signaling pathway increased water-use efficiency of A17 plants by decreasing the stomatal aperture and transpiration rate. In contrast, the water potential of sta-1 plants (unable to close stomata) was too low to support xylem absorption activity of aphids; the aphids on sta-1 plants had the highest hemolymph osmolarity and lowest abundance under drought conditions. Taken together this study illustrates the significance of cross-talk between biotic-abiotic signaling pathways in plant-aphid interaction, and reveals the mechanisms leading to alter

  13. Host Plant Volatiles and the Sexual Reproduction of the Potato Aphid, Macrosiphum euphorbiae

    Directory of Open Access Journals (Sweden)

    Jessica Hurley

    2014-10-01

    Full Text Available In late summer, heteroecious aphids, such as the potato aphid, Macrosiphum euphorbiae, move from their secondary summer host plants to primary host plants, where the sexual oviparae mate and lay diapausing eggs. We tested the hypothesis that volatiles of the primary host, Rosa rugosa, would attract the gynoparae, the parthenogenetic alate morph that produce oviparae, as well as the alate males foraging for suitable mates. In wind tunnel assays, both gynoparae and males oriented towards and reached rose cuttings significantly more often than other odour sources, including potato, a major secondary host. The response of males was as high to rose cuttings alone as to potato with a calling virgin oviparous female. These findings are discussed within the seasonal ecology of host alternating aphids.

  14. The effect of co-infestation by conspecific and heterospecific aphids on the feeding behaviour of Nasonovia ribisnigri on resistant and susceptible lettuce cultivars

    NARCIS (Netherlands)

    Broeke, ten Cindy J.M.; Dicke, Marcel; Loon, van Joop J.A.

    2017-01-01

    Aphid saliva can suppress the blocking of sieve elements, a reaction that plants employ to inhibit aphid feeding, but aphid saliva can also elicit plant defence responses. Such plant responses might affect interactions between different aphid species and intraspecifically, e.g. among different

  15. Effects of different corn silage: Alfalfa silage ratios and full fat ...

    African Journals Online (AJOL)

    Full fat extruded soybeans addition increased the ether extract in diets and content of conjugated linoleic acids in milk, but it had no effect on fat, protein and lactose content in milk. Milk fat and lactose were not affected by replacing corn silage with alfalfa silage in diets. Increasing alfalfa silage content in the diets increased ...

  16. Effects of imidacloprid and clothianidin seed treatments on wheat aphids and their natural enemies on winter wheat.

    Science.gov (United States)

    Zhang, Peng; Zhang, Xuefeng; Zhao, Yunhe; Wei, Yan; Mu, Wei; Liu, Feng

    2016-06-01

    Wheat aphid (Hemiptera: Aphididae) is one of the major pests of winter wheat and has posed a significant threat to winter wheat production in China. Although neonicotinoid insecticidal seed treatments have been suggested to be a control method, the season-long efficacy on pests and the impact on their natural enemies are still uncertain. Experiments were conducted to determine the efficacy of imidacloprid and clothianidin on the control of aphids, the number of their natural enemies and the emergence rate and yield of wheat during 2011-2014. Imidacloprid and clothianidin seed treatments had no effect on the emergence rate of winter wheat and could prevent yield losses and wheat aphid infestations throughout the winter wheat growing season. Furthermore, their active ingredients were detected in winter wheat leaves up to 200 days after sowing. Imidacloprid and clothianidin seed treatments had no adverse effects on ladybirds, hoverflies or parasitoids, and instead increased the spider-aphid ratios. Wheat seeds treated with imidacloprid and clothianidin were effective against wheat aphids throughout the winter wheat growing season and reduced the yield loss under field conditions. Imidacloprid and clothianidin seed treatments may be an important component of the integrated management of wheat aphids on winter wheat. © 2015 Society of Chemical Industry. © 2015 Society of Chemical Industry.

  17. The effect of co-infestation by conspecific and heterospecific aphids on the feeding behaviour of Nasonovia ribisnigri on resistant and susceptible lettuce cultivars

    OpenAIRE

    Broeke, ten, Cindy J.M.; Dicke, Marcel; Loon, van, Joop J.A.

    2017-01-01

    Aphid saliva can suppress the blocking of sieve elements, a reaction that plants employ to inhibit aphid feeding, but aphid saliva can also elicit plant defence responses. Such plant responses might affect interactions between different aphid species and intraspecifically, e.g. among different biotypes. The objectives of our study were to investigate if feeding behaviour and performance of two biotypes of the lettuce aphid Nasonovia ribisnigri are affected by (1) feeding by the other biotype ...

  18. Field evaluation of Bt cotton crop impact on nontarget pests: cotton aphid and boll weevil.

    Science.gov (United States)

    Sujii, E R; Togni, P H B; de A Ribeiro, P; de A Bernardes, T; Milane, P V G N; Paula, D P; Pires, C S S; Fontes, E M G

    2013-02-01

    Bt cotton plants expressing Cry1Ac protein have high specificity for the control of lepidopteran larvae. However, studies conducted in several countries have shown these plants have a differential impact on nontarget herbivores. The aim of this study was to compare the colonization rates and population abundance of the cotton aphid, Aphis gossypii Glover (Hemiptera: Aphididae) and the boll weevil, Anthonomus grandis Boheman (Coleoptera: Curculionidae), in plots of Bt (Nuopal) and non-Bt cotton (Delta Opal) in an experimental field in Brasilia, DF, Brazil. No difference was observed in the preference and colonization by winged aphids to plants from the two treatments. There was no significant difference in abundance of wingless aphids or in the production of winged aphids between treatments. Apparently, the parameters that control factors such as fecundity, survival, and dispersal were similar on both Bt and non-Bt plants. Monitoring of plants for coccinellids, a specialist predator of aphids, and ants that act on the dispersal of aphids among plants showed no significant difference between Bt and non-Bt plants, supporting the inference above. Regarding the effect on boll weevil, there was also no significant difference between treatments in the total number of fruiting structures attacked in each plot, the percentage of fruiting structures attacked per plant or on the number of weevils emerging from fruits with boll weevil damage from egg-laying, when damaged fruit samples were held in the laboratory. Based on these results, we conclude that there is no impact of Bt cotton crop expressing Cry1Ac on the nontarget herbivores tested under field conditions.

  19. Do glyphosate resistant feral plants and hay fields spread the transgene to conventional alfalfa seed fields?

    Science.gov (United States)

    In addition to meeting domestic needs, large amounts of alfalfa seed and hay produced in the US are being exported overseas. Because alfalfa is an insect pollinated crop, gene flow is a concern. Adding to this alfalfa readily naturalizes along roadsides, irrigation ditches, and unmanaged habitats; a...

  20. Effect of ant attendance by Monomorium minimum (Buckley) (Hymenoptera: Formicidae) on predation and parasitism of the soybean aphid Aphis glycines Matsumura (Hemiptera: Aphididae).

    Science.gov (United States)

    Herbert, John J; Horn, David J

    2008-10-01

    Ant attendance is known to affect the population dynamics of aphids and may increase or decrease aphid populations through stimulation, predation, or protection. In this study, we performed a series of laboratory experiments to examine the effects of ant attendance on populations of the soybean aphid Aphis glycines. Aphid colonies were exposed to the predators Harmonia axyridis (Coccinellidae) and Orius insidiosus (Anthocoridae) and a parasitoid Aphidius colemani (Aphidiidae) in the presence and absence of attending Monomorium minimum (Formicidae). We also tested for direct effects of ant attendance in the absence of natural enemies. Ants attending soybean aphid populations were observed harassing or killing O. insidiosus and H. axyridis. Attendance interfered with both predator species, resulting in reduced predation and an increase in aphid numbers up to 10-fold in the presence of ants. Ants were not observed directly interfering with the parasitoid A. colemani, but the number of parasitized aphids was higher in aphid colonies that were left unattended by ants.

  1. Is Reduction in Yield Potential of Some Brassicaceous Species Due to Aphid Infestation Associated with the Changes in Stomatal Factors of Photosynthesis

    International Nuclear Information System (INIS)

    Razaq, M.; Farooq, M.; Abbas, G.; Rehman, H. M.; Iqbal, M.

    2016-01-01

    Aphids cause heavy yield losses to Brassicaceous species by affecting various physiological and biochemical processes including photosynthesis. In the present study, seasonal activity of aphid population and its impact on some brassicaceous species was assessed. Three brassicaceous species (Brassica campestris, Brassica carinata, Eruca sativa) were grown in field following standard agricultural practices. Plants of control plots retained aphid free by insecticide spray, whereas treatment plots were freely allowed for aphid infestation. There was also intermediate treatment of partial aphid infestation where insecticidal spray was applied two times. Peak populations of both aphid species were observed in the 2nd week of March during which plant photosynthetic attributes were recorded. At the time of maturity, yield attributes were also recorded. From the results, it is obvious that application of insecticide significantly reduced the aphid populations on the three brassicaceous species and enhanced the crop yield. Yield losses due to aphid infestation were maximal in Brassica campestris followed by B. carinata whereas it was minimal in Eruca sativa. Yield losses in Brassica campestris and B. carinata were due to reduction in number of pods per plant, number of seeds per pod and size of seeds, whereas yield losses due to aphid infestation in Eruca sativa was mainly attributed to reduction in number of pods per plant. Although insecticidal spray reduced the aphid population and increased growth and productivity of all brassicaceous species, it did not change photosynthetic capacity of all plants except in Eruca sativa. Moreover, growth and yield reduction was not associated with stomatal factors of photosynthesis. Chlorophyll contents measured as SPAD values were reduced due to aphid infestation which is positively associated with yield reduction. Insecticidal spray increased chlorophyll contents in these three brassicaceous species by reducing aphid population

  2. RAPD analysis of alfalfa DNA mutation via N+ implantation

    International Nuclear Information System (INIS)

    Li Yufeng; Huang Qunce; Yu Zengliang; Liang Yunzhang

    2003-01-01

    Germination capacity of alfalfa seeds under low energy N + implantation manifests oscillations going down with dose strength. From analyzing alfalfa genome DNA under low energy N + implantation by RAPD (Random Amplified Polymorphous DNA), it is recommended that 30 polymorphic DNA fragments be amplified with 8 primers in total 100 primers, and fluorescence intensity of the identical DNA fragment amplified by RAPD is different between CK and treatments. Number of different polymorphic DNA fragments between treatment and CK via N + implantation manifests going up with dose strength

  3. Environmental impact assessment of alfalfa (Medicago sativa L.) hay production.

    Science.gov (United States)

    Bacenetti, Jacopo; Lovarelli, Daniela; Tedesco, Doriana; Pretolani, Roberto; Ferrante, Valentina

    2018-09-01

    On-farm production of hay and high-protein-content feed has several advantages such as diversification of on-farm cultivated crops, reduction of off-farm feed concentrates transported over long distances and a reduction in runoff during the winter season if grown crops are perennial. Among those crops cultivated for high-protein-content feed, alfalfa (Medicago sativa L.) is one of the most important in the Italian context. Nevertheless, up to now, only a few studies have assessed the environmental performance of alfalfa hay production. In this study, using the Life Cycle Assessment approach, the environmental impact of alfalfa hay production in Northern Italy was analyzed. More in detail, two production practices (without and with irrigation) were compared. The results show that alfalfa hay production in irrigated fields has a better environmental performance compared to non-irrigated production, mainly because of the yield increase achieved with irrigation. In particular, for the Climate Change impact category, the impact is equal to 84.54 and 80.21kgCO 2 /t of hay for the scenario without and with irrigation, respectively. However, for two impact categories (Ozone Depletion and Human Toxicity-No Cancer Effect), the impact of irrigation completely offsets the yield increase, and the cultivation practice without irrigation shows the best environmental performance. For both scenarios, the mechanization of harvest is the main environmental hotspot, mostly due to fuel consumption and related combustion emissions. Wide differences were highlighted by comparing the two scenarios with the Ecoinvent process of alfalfa hay production; these differences are mostly due to the cultivation practice and, in particular, to the more intensive fertilization in Swiss production. Copyright © 2018 Elsevier B.V. All rights reserved.

  4. Photosynthate partitioning and nitrogen fixation of alfalfa and birdsfoot trefoil

    International Nuclear Information System (INIS)

    Shieh, W.J.

    1985-01-01

    Nodule mass and number are usually correlated with rates of nitrogen fixation in legumes. Birdsfoot trefoil (Lotus corniculatus L.) with more than twice the nodule number and mass, however, fixes far less nitrogen than alfalfa (Medicago sativa L.) at the same age. In this research, photosynthesis and photosynthate partitioning and utilization in relation to nitrogen fixation of alfalfa and birdsfoot trefoil were examined in order to determine their relationship to nitrogen fixation potential. Photosynthate to nodules was studied using 14 CO 2 labeling techniques. Partitioning patterns were altered by shading and dark depletion treatments. Efficiency of photosynthate utilization was examined by determining turnover of 14 C photosynthate in nodule metabolites and by studying rates of cyanide-resistant and cyanide-sensitive O 2 uptake. Alfalfa nodule activity was greater than trefoil expressed on a hole pot or nodule dry weight basis. Both shading and dark treatments significantly reduced nodule activity as estimated by the acetylene reduction assay. Shoots of both species were found to be the dominant sinks for photosynthate. Percentage 14 C recovered in alfalfa roots was more than twice that of trefoil at 1,2,3,4 and 24 h after labeling. Greater relative specific radioactivity (RSA) in nodules of both species suggests that they were stronger sinks for current photosynthate than roots

  5. Proteomic Analysis of Aphid-Resistant and -Sensitive Rose (Rosa Hybrida) Cultivars at Two Developmental Stages.

    Science.gov (United States)

    Muneer, Sowbiya; Jeong, Hai Kyoung; Park, Yoo Gyeong; Jeong, Byoung Ryong

    2018-05-25

    The rose is one the most commercially grown and costly ornamental plants because of its aesthetic beauty and aroma. A large number of pests attack its buds, flowers, leaves, and stem at every growing stage due to its high sugar content. The most common pest on roses are aphids which are considered to be the major cause for product loss. Aphid infestations lead to major changes in rose plants, such as large and irregular holes in petals, intact leaves and devouring tissues. It is hypothesized that different cut rose cultivars would have different levels of sensitivity or resistance to aphids, since different levels of infestation are observed in commercially cut rose production greenhouses. The present work compared four cut rose cultivars which were bred in Korea and were either resistant or sensitive to aphid infestation at different flower developmental stages. An integrative study was conducted using comprehensive proteome analyses. Proteins related to ubiquitin metabolism and the stress response were differentially expressed due to aphid infestation. The regulations and possible functions of identified proteins are presented in detail. The differential expressions of the identified proteins were validated by immunoblotting and blue native page. In addition, total sugar and carbohydrate content were also observed.

  6. Animal feed compositions containing phytase derived from transgenic alfalfa and methods of use thereof

    Science.gov (United States)

    Austin-Phillips, Sandra; Koegel, Richard G.; Straub, Richard J.; Cook, Mark

    1999-01-01

    A value-added composition of matter containing plant matter from transgenic alfalfa which expresses exogenous phytase activity is disclosed. The phytase activity is a gene product of an exogenous gene encoding for phytase which has been stably incorporated into the genome of alfalfa plants. The transgenic alfalfa expresses phytase activity in nutritionally-significant amounts, thereby enabling its use in animal feeds to eliminate the need for phosphorous supplementation of livestock, poultry, and fish feed rations.

  7. Activity of aphids associated with lettuce and broccoli in Spain and their efficiency as vectors of Lettuce mosaic virus.

    Science.gov (United States)

    Nebreda, M; Moreno, A; Pérez, N; Palacios, I; Seco-Fernández, V; Fereres, A

    2004-03-01

    This research sought to identify the aphid virus vector species associated with lettuce and broccoli crops in Spain, and to determine their population dynamics and ability to transmit Lettuce mosaic virus (LMV). Green tile traps and Moericke yellow water-pan traps were used to monitor aphid flights during the spring and autumn growing seasons of 2001. Aphid species feeding on lettuce were counted weekly. The transmission efficiencies of LMV were determined for the aphid species caught most frequently. The Moericke traps generally caught more aphid species than the tile trap, but the latter was the most suitable to estimate flight activity of species involved in virus spread. Spring aphid catches indicated that the main aphid species landing on lettuce in the regions of Madrid and Murcia was Hyperomyzus lactucae, but Brachycaudus helichrysi was also abundant in both regions. In broccoli in the Navarra region, the most abundant species in spring were Aphis fabae, B. helichrysi and H. lactucae. In autumn-sown crops, the main species landing on lettuce in the Madrid region were Hyadaphis coriandri and Aphis spiraecola. In Murcia, A. spiraecola and Myzus persicae were the most abundant, while in Navarra, Therioaphis trifolii, and various Aphis spp. were the most numerous landing on broccoli. The main aphid species colonising lettuce was Nasonovia ribisnigri, but other less abundant colonising species were Aulacorthum solani and Macrosiphum euphorbiae. The most efficient vectors of LMV were M. persicae, Aphis gossypii and M. euphorbiae, while A. fabae and H. lactucae transmitted with low efficiency, and Rhopalosiphum padi and N. ribisnigri did not transmit. Occurrence of LMV epidemics in central Spain in relation to aphid flights and the role of weeds as virus reservoirs is discussed.

  8. El cultivo de alfalfa utilizando agua de perforación, agua residual urbana y precipitaciones The cultivation of alfalfa using artesian well water, urban wastewater and rainfall

    Directory of Open Access Journals (Sweden)

    José O. Plevich

    2012-12-01

    Full Text Available El objetivo de este trabajo fue analizar la producción de biomasa aérea, la eficiencia del uso de agua y el valor nutritivo de alfalfa cultivada aplicando riego con agua residual urbana, agua de perforación y un testigo (precipitaciones, en el Campus de la Universidad Nacional de Rio Cuarto (Córdoba-Argentina. Los tratamientos de riego tuvieron un efecto positivo sobre la producción de biomasa aérea obteniéndose un 24% más de producción de biomasa que en la situación de secano (precipitaciones. Entre los tratamientos con riego también se manifestaron diferencias estadísticamente significativas. La alfalfa regada con aguas residuales urbana supero en un 19% a la cultivada con agua de perforación. La eficiencia del uso del agua por parte del cultivo se incrementó cuando el riego se realizó con aguas residuales urbanas. Además, se determinó que la alfalfa regada con agua residual, supera los valores nutritivos del cultivo que crece en condiciones sin riego; encontrándose 39% más de proteínas, 14% más de digestibilidad e igual porcentaje de energía metabólica. Se puede concluir que el agua residual urbana representa otra posible fuente de agua, factible de ingresar al suelo y estar a disposición para el cultivo de alfalfa.The objective of this study was to analyse the production of alfalfa biomass, the efficiency of water use and the nutritional value of forage, inside an irrigation structure of an experimental facility that uses treated urban wastewater, artesian well water and rainfall, at the campus of the Universidad National de Rio Cuarto (Córdoba-Argentina. The irrigation treatment had a positive effect on the production of biomass of alfalfa. On an average 24% increase in production was observed when compared to dry-land farming. Regarding the quality of the irrigation water, statistical differences in production were observed, the irrigation with urban wastewater produced 19% more than that of well water. The

  9. Mechanisms of qualitative and quantitative resistance to Aphanomyces root rot in alfalfa

    Science.gov (United States)

    Aphanomyces root rot (ARR), caused by Aphanomyces euteiches, is one of the most important diseases of alfalfa (Medicago sativa) in the United States. Two races of the pathogen are currently recognized. Most modern alfalfa cultivars have high levels of resistance to race 1 but few cultivars have resi...

  10. The Role of Proanthocyanidins Complex in Structure and Nutrition Interaction in Alfalfa Forage

    Directory of Open Access Journals (Sweden)

    Arjan Jonker

    2016-05-01

    Full Text Available Alfalfa (Medicago sativa L. is one of the main forages grown in the world. Alfalfa is a winter hardy, drought tolerant, N-fixing legume with a good longevity, high yield, high nutrient levels, high digestibility, unique structural to non-structural components ratio, high dry matter intake, and high animal productivity per hectare. However, its main limitation is its excessively rapid initial rate of protein degradation in the rumen, which results in pasture bloat and inefficient use of protein with consequent excessive excretions of nitrogen into the environment. Proanthocyanidins are secondary plant metabolites that can bind with protein and thereby reduce the rate and extent of ruminal protein degradation. However, these secondary metabolites do not accumulate in alfalfa. This review aims to firstly describe the events involved in the rapid release of protein from alfalfa and its effect on ruminant nutrition, environmental pollution, and pasture bloat; secondly, to describe occurrence, structure, functions and benefits of moderate amounts of proanthocyanidin; and finally, to describe the development of alfalfa which accumulates moderate amounts of proanthocyanidins. The emphasis of this review focuses on the role of proanthocyanidins compounds in structure and nutrition interaction in ruminant livestock systems.

  11. The Role of Proanthocyanidins Complex in Structure and Nutrition Interaction in Alfalfa Forage.

    Science.gov (United States)

    Jonker, Arjan; Yu, Peiqiang

    2016-05-23

    Alfalfa (Medicago sativa L.) is one of the main forages grown in the world. Alfalfa is a winter hardy, drought tolerant, N-fixing legume with a good longevity, high yield, high nutrient levels, high digestibility, unique structural to non-structural components ratio, high dry matter intake, and high animal productivity per hectare. However, its main limitation is its excessively rapid initial rate of protein degradation in the rumen, which results in pasture bloat and inefficient use of protein with consequent excessive excretions of nitrogen into the environment. Proanthocyanidins are secondary plant metabolites that can bind with protein and thereby reduce the rate and extent of ruminal protein degradation. However, these secondary metabolites do not accumulate in alfalfa. This review aims to firstly describe the events involved in the rapid release of protein from alfalfa and its effect on ruminant nutrition, environmental pollution, and pasture bloat; secondly, to describe occurrence, structure, functions and benefits of moderate amounts of proanthocyanidin; and finally, to describe the development of alfalfa which accumulates moderate amounts of proanthocyanidins. The emphasis of this review focuses on the role of proanthocyanidins compounds in structure and nutrition interaction in ruminant livestock systems.

  12. Exposure to bacterial signals does not alter pea aphids' survival upon a second challenge or investment in production of winged offspring.

    Directory of Open Access Journals (Sweden)

    Bas ter Braak

    Full Text Available Pea aphids have an obligate nutritional symbiosis with the bacteria Buchneraaphidicola and frequently also harbor one or more facultative symbionts. Aphids are also susceptible to bacterial pathogen infections, and it has been suggested that aphids have a limited immune response towards such pathogen infections compared to other, more well-studied insects. However, aphids do possess at least some of the genes known to be involved in bacterial immune responses in other insects, and immune-competent hemocytes. One possibility is that immune priming with microbial elicitors could stimulate immune protection against subsequent bacterial infections, as has been observed in several other insect systems. To address this hypothesis we challenged aphids with bacterial immune elicitors twenty-four hours prior to live bacterial pathogen infections and then compared their survival rates to aphids that were not pre-exposed to bacterial signals. Using two aphid genotypes, we found no evidence for immune protection conferred by immune priming during infections with either Serratia marcescens or with Escherichia coli. Immune priming was not altered by the presence of facultative, beneficial symbionts in the aphids. In the absence of inducible immune protection, aphids may allocate energy towards other defense traits, including production of offspring with wings that could escape deteriorating conditions. To test this, we monitored the ratio of winged to unwinged offspring produced by adult mothers of a single clone that had been exposed to bacterial immune elicitors, to live E. coli infections or to no challenge. We found no correlation between immune challenge and winged offspring production, suggesting that this mechanism of defense, which functions upon exposure to fungal pathogens, is not central to aphid responses to bacterial infections.

  13. Potential candidates for biological control of the black bean aphid Aphis fabae in Serbia

    Directory of Open Access Journals (Sweden)

    Stanković, S.S.

    2015-09-01

    Full Text Available The black bean aphid is widely spread aphid species in the Palaearctic, known to attack over 1150 plant species. Because some of the host plants are of great agricultural interest, Aphis fabae represent a very important pest. We assembled all data concerning the presence of this pest and connected it in tritrophic associations. In the period of 24 years investigation on the territory of Serbia it has been recorded in 107 trophic associations. In total there are 145 findings of A. fabae parasitized by 19 taxa of Aphidiinae (Brackonidae from seven genera. The most suitable biocontrol agents for the black bean aphid are Lysiphlebus fabarum, Binodoxys angelicae, Lipolesis gracilis and the introduced species Lysiphlebus testaceipes.

  14. Expression Profiling of Selected Glutathione Transferase Genes in Zea mays (L.) Seedlings Infested with Cereal Aphids

    Science.gov (United States)

    Sytykiewicz, Hubert; Chrzanowski, Grzegorz; Czerniewicz, Paweł; Sprawka, Iwona; Łukasik, Iwona; Goławska, Sylwia; Sempruch, Cezary

    2014-01-01

    The purpose of this report was to evaluate the expression patterns of selected glutathione transferase genes (gst1, gst18, gst23 and gst24) in the tissues of two maize (Zea mays L.) varieties (relatively resistant Ambrozja and susceptible Tasty Sweet) that were colonized with oligophagous bird cherry-oat aphid (Rhopalosiphum padi L.) or monophagous grain aphid (Sitobion avenae L.). Simultaneously, insect-triggered generation of superoxide anion radicals (O2 •−) in infested Z. mays plants was monitored. Quantified parameters were measured at 1, 2, 4, 8, 24, 48 and 72 h post-initial aphid infestation (hpi) in relation to the non-infested control seedlings. Significant increases in gst transcript amounts were recorded in aphid-stressed plants in comparison to the control seedlings. Maximal enhancement in the expression of the gst genes in aphid-attacked maize plants was found at 8 hpi (gst23) or 24 hpi (gst1, gst18 and gst24) compared to the control. Investigated Z. mays cultivars formed excessive superoxide anion radicals in response to insect treatments, and the highest overproduction of O2 •− was noted 4 or 8 h after infestation, depending on the aphid treatment and maize genotype. Importantly, the Ambrozja variety could be characterized as having more profound increments in the levels of gst transcript abundance and O2 •− generation in comparison with the Tasty Sweet genotype. PMID:25365518

  15. Aphid effects on rhizosphere microorganisms and microfauna depend more on barley growth phase than on soil fertilization

    DEFF Research Database (Denmark)

    Madsen, Mette Vestergård; Strandmark, Lisa Bjørnlund; Christensen, Søren

    2004-01-01

    This paper gives the first reports on aphid effects on rhizosphere organisms as influenced by soil nutrient status and plant development. Barley plants grown in pots fertilized with N but without P (N), with N and P (NP), or not fertilized (0) were sampled in the early growth phase (day 25), 1 week...... before and 1 week after spike emergence. Aphids were added 16 days before sampling was carried out. In a separate experiment belowground respiration was measured on N and NP fertilized plant–soil systems with aphid treatments comparable to the first experiment. Aphids reduced numbers of rhizosphere...... experimental conditions with nematodes being the dominant bacterial grazers at N fertilization and Protozoa in the NP treatment before spike emergence....

  16. New invasive species of aphids (Hemiptera, Aphididae in Serbia and Montenegro

    Directory of Open Access Journals (Sweden)

    Petrović-Obradović Olivera

    2010-01-01

    Full Text Available Three new invasive species of aphids have been found in Serbia: Chaitophorus populifolli Essig, Myzocallis walshii (Monell and Trichosiphonaphis polygonifoliae (Shinji and two have been found in Montenegro: Aphis illinoisensis Shimer and Tinocallis kahawaluokalani (Kirkaldy. A. illinoisensis is a pest of the grapevine, T. polygonifoliae, feeds on a decorative shrub (Lonicera and the other three feed on trees (Populus, Quercus and Lagerostroemia. Three of the species are American aphids and two are of Asian origin. Their morphology, illustrated by original drawings and data on the biology and distribution are given. .

  17. Prevalence of single nucleotide polymorphism among 27 diverse alfalfa genotypes as assessed by transcriptome sequencing

    Directory of Open Access Journals (Sweden)

    Li Xuehui

    2012-10-01

    Full Text Available Abstract Background Alfalfa, a perennial, outcrossing species, is a widely planted forage legume producing highly nutritious biomass. Currently, improvement of cultivated alfalfa mainly relies on recurrent phenotypic selection. Marker assisted breeding strategies can enhance alfalfa improvement efforts, particularly if many genome-wide markers are available. Transcriptome sequencing enables efficient high-throughput discovery of single nucleotide polymorphism (SNP markers for a complex polyploid species. Result The transcriptomes of 27 alfalfa genotypes, including elite breeding genotypes, parents of mapping populations, and unimproved wild genotypes, were sequenced using an Illumina Genome Analyzer IIx. De novo assembly of quality-filtered 72-bp reads generated 25,183 contigs with a total length of 26.8 Mbp and an average length of 1,065 bp, with an average read depth of 55.9-fold for each genotype. Overall, 21,954 (87.2% of the 25,183 contigs represented 14,878 unique protein accessions. Gene ontology (GO analysis suggested that a broad diversity of genes was represented in the resulting sequences. The realignment of individual reads to the contigs enabled the detection of 872,384 SNPs and 31,760 InDels. High resolution melting (HRM analysis was used to validate 91% of 192 putative SNPs identified by sequencing. Both allelic variants at about 95% of SNP sites identified among five wild, unimproved genotypes are still present in cultivated alfalfa, and all four US breeding programs also contain a high proportion of these SNPs. Thus, little evidence exists among this dataset for loss of significant DNA sequence diversity from either domestication or breeding of alfalfa. Structure analysis indicated that individuals from the subspecies falcata, the diploid subspecies caerulea, and the tetraploid subspecies sativa (cultivated tetraploid alfalfa were clearly separated. Conclusion We used transcriptome sequencing to discover large numbers of SNPs

  18. Studying, the Insecticidal Effects of Melia azedarach and Citrus limonum Extracts on Two Aphid Species

    Directory of Open Access Journals (Sweden)

    maryam Pahlavan Yali

    2018-01-01

    Full Text Available Introduction: Wheat (Triticum aestivum L. is the most principal plant food for 35 percent of the world's population, and canola (Brassica napus L. is one of the most important brassicaceous crops that play a major role in the development of edible oil. The greenbug, Schizaphis graminum (Rondani and cabbage aphid, Brevicoryne brassicae (L. are the main pests of wheat and canola, respectively, which can considerably limit profitable production of these crops either through direct feeding or via transmission of plant pathogenic viruses. Although chemical control is the most effective and easiest way to control aphids, but this method causes problems such as pesticide residues in food and environment, and development of resistance to insecticides. The utilization of plant extracts is an environmentally safe method that can be used in control of these aphids. Among these, the products of the Melia seed (Melia azedarach Linnaeus and lemon peel (Citrus limonum Risso can be noted. Negative associations between phenolic compounds present in plant species and aphid’s invasion have been recorded for some aphid species. In this study, our goal was to determine the amount of phenol in plant extracts of Melia seed and lemon peel and evaluate the toxicity of these compounds on the wheat aphid and cabbage aphid in various doses after different time periods. Materials and methods: This research was conducted in a growth chamber (temperature 25 ± 1˚C, 65± 5% RH and a photoperiod of 16L: 8D. S. graminum and B. brassicae were bred on wheat (Pishtaz cultivar and canola (Hyola401 cultivar, respectively. The extraction of Melia seed and lemon peel was carried out and then contact toxicity bioassay was done to evaluate the insecticidal effects of these extracts on nymphs of wheat and cabbage aphids using a completely randomized design. The leaves of wheat and canola plants, impregnated with three different concentrations of each extract (10, 50 and 80 g/ml and

  19. Resistance of Wheat Accessions to the English Grain Aphid Sitobion avenae

    Science.gov (United States)

    Hu, Xiang-Shun; Liu, Ying-Jie; Wang, Yu-Han; Wang, Zhe; Yu, Xin-lin; Wang, Bo; Zhang, Gai-Sheng; Liu, Xiao-Feng; Hu, Zu-Qing; Zhao, Hui-Yan; Liu, Tong-Xian

    2016-01-01

    The English grain aphid, Sitobion avenae, is a major pest species of wheat crops; however, certain varieties may have stronger resistance to infestation than others. Here, we investigated 3 classical resistance mechanisms (antixenosis, antibiosis, and tolerance) by 14 wheat varieties/lines to S. avenae under laboratory and field conditions. Under laboratory conditions, alatae given the choice between 2 wheat varieties, strongly discriminated against certain varieties. Specifically, the ‘Amigo’ variety had the lowest palatability to S. avenae alatae of all varieties. ‘Tm’ (Triticum monococcum), ‘Astron,’ ‘Xanthus,’ ‘Ww2730,’ and ‘Batis’ varieties also had lower palatability than other varieties. Thus, these accessions may use antibiosis as the resistant mechanism. In contrast, under field conditions, there were no significant differences in the number of alatae detected on the 14 wheat varieties. One synthetic line (98-10-30, a cross between of Triticum aestivum (var. Chris) and Triticum turgidum (var. durum) hybridization) had low aphid numbers but high yield loss, indicating that it has high antibiosis, but poor tolerance. In comparison, ‘Amigo,’ ‘Xiaoyan22,’ and some ‘186Tm’ samples had high aphid numbers but low yield loss rates, indicating they have low antibiosis, but good tolerance. Aphid population size and wheat yield loss rates greatly varied in different fields and years for ‘98-10-35,’ ‘Xiaoyan22,’ ‘Tp,’ ‘Tam200,’ ‘PI high,’ and other ‘186Tm’ samples, which were hybrid offspring of T. aestivum and wheat related species. Thus, these germplasm should be considered for use in future studies. Overall, S. avenae is best adapted to ‘Xinong1376,’ because it was the most palatable variety, with the greatest yield loss rates of all 14 wheat varieties. However, individual varieties/lines influenced aphid populations differently in different years. Therefore, we strongly recommend a combination of

  20. Stress responses in alfalfa (Medicago sativa L.)

    International Nuclear Information System (INIS)

    Kessmann, H.; Edwards, R.; Dixon, R.A.; Geno, P.W.

    1990-01-01

    The isoflavonoid conjugates medicarpin-3-O-glucoside-6 double-prime-O-malonate (MGM), afrormosin-7-O-glucoside (AG), and afrormosin-7-O-glucoside-6 double-prime-O-malonate (AGM) were isolated and characterized from cell suspension cultures of alfalfa (Medicago sativa L.), where they were the major constitutive secondary metabolites. They were also found in alfalfa roots but not in other parts of the plant. The phytoalexin medicarpin accumulated rapidly in suspension cultured cells treated with elicitor from Colletotrichum lindemuthianum, and this was subsequently accompanied by an increase in the levels of MGM. In contrast, net accumulation of afrormosin conjugates was not affected by elicitor treatment. Labeling studies with [ 14 C]phenylalanine indicated that afrormosin conjugates were the major de novo synthesized isoflavonoid products in unelicited cells. During elicitation, [ 14 C]phenylalanine was incorporated predominantly into medicarpin, although a significant proportion of the newly synthesized medicarpin was also conjugated. Treatment of 14 C-labeled, elicited cells with L-α-aminooxy-β-phenylpropionic acid, a potent inhibitor of PAL activity in vivo, resulted in the initial appearance of labeled medicarpin of very low specific activity, suggesting that the phytoalexin could be released from a preformed conjugate under these conditions. Our data draw attention to the involvement of isoflavone hydroxylases during the constitutive and elicitor-induced accumulation of isoflavonoids and their conjugates in alfalfa cell cultures

  1. Isolated and Community Contexts Produce Distinct Responses by Host Plants to the Presence of Ant-Aphid Interaction: Plant Productivity and Seed Viability

    Science.gov (United States)

    Santiago, Graziele Silva; Zurlo, Luana Fonseca; Ribas, Carla Rodrigues; Carvalho, Rafaela Pereira; Alves, Guilherme Pereira; Carvalho, Mariana Comanucci Silva; Souza, Brígida

    2017-01-01

    Ant-aphid interactions may affect host plants in several ways, however, most studies measure only the amount of fruit and seed produced, and do not test seed viability. Therefore, the aim of this study was to assess the effects of the presence of ant-aphid interactions upon host plant productivity and seed viability in two different contexts: isolated and within an arthropod community. For this purpose we tested the hypothesis that in both isolated and community contexts, the presence of an ant-aphid interaction will have a positive effect on fruit and seed production, seed biomass and rate of seed germination, and a negative effect on abnormal seedling rates, in comparison to plants without ants. We performed a field mesocosm experiment containing five treatments: Ant-aphid, Aphid, Community, Ant-free community and Control. We counted fruits and seeds produced by each treatment, and conducted experiments for seed biomass and germinability. We found that in the community context the presence of an ant-aphid interaction negatively affected fruit and seed production. We think this may be because aphid attendance by tending-ants promotes aphid damage to the host plant, but without an affect on seed weight and viability. On the other hand, when isolated, the presence of an ant-aphid interaction positively affected fruit and seed production. These positive effects are related to the cleaning services offered to aphids by tending-ants, which prevent the development of saprophytic fungi on the surface of leaves, which would cause a decrease in photosynthetic rates. Our study is important because we evaluated some parameters of plant fitness that have not been addressed very well by other studies involving the effects of ant-aphid interactions mainly on plants with short life cycles. Lastly, our context dependent approach sheds new light on how ecological interactions can vary among different methods of crop management. PMID:28141849

  2. Isolated and Community Contexts Produce Distinct Responses by Host Plants to the Presence of Ant-Aphid Interaction: Plant Productivity and Seed Viability.

    Directory of Open Access Journals (Sweden)

    Ernesto Oliveira Canedo-Júnior

    Full Text Available Ant-aphid interactions may affect host plants in several ways, however, most studies measure only the amount of fruit and seed produced, and do not test seed viability. Therefore, the aim of this study was to assess the effects of the presence of ant-aphid interactions upon host plant productivity and seed viability in two different contexts: isolated and within an arthropod community. For this purpose we tested the hypothesis that in both isolated and community contexts, the presence of an ant-aphid interaction will have a positive effect on fruit and seed production, seed biomass and rate of seed germination, and a negative effect on abnormal seedling rates, in comparison to plants without ants. We performed a field mesocosm experiment containing five treatments: Ant-aphid, Aphid, Community, Ant-free community and Control. We counted fruits and seeds produced by each treatment, and conducted experiments for seed biomass and germinability. We found that in the community context the presence of an ant-aphid interaction negatively affected fruit and seed production. We think this may be because aphid attendance by tending-ants promotes aphid damage to the host plant, but without an affect on seed weight and viability. On the other hand, when isolated, the presence of an ant-aphid interaction positively affected fruit and seed production. These positive effects are related to the cleaning services offered to aphids by tending-ants, which prevent the development of saprophytic fungi on the surface of leaves, which would cause a decrease in photosynthetic rates. Our study is important because we evaluated some parameters of plant fitness that have not been addressed very well by other studies involving the effects of ant-aphid interactions mainly on plants with short life cycles. Lastly, our context dependent approach sheds new light on how ecological interactions can vary among different methods of crop management.

  3. Deciphering the role of NADPH oxidase in complex interactions between maize (Zea mays L.) genotypes and cereal aphids.

    Science.gov (United States)

    Sytykiewicz, Hubert

    2016-07-22

    Plant NADPH oxidases (NOXs) encompass a group of membrane-bound enzymes participating in formation of reactive oxygen species (ROS) under physiological conditions as well as in response to environmental stressors. The purpose of the survey was to unveil the role of NADPH oxidase in pro-oxidative responses of maize (Zea mays L.) seedling leaves exposed to cereal aphids' infestation. The impact of apteral females of bird cherry-oat aphid (Rhopalosiphum padi L.) and grain aphid (Sitobion avenae F.) feeding on expression levels of all four NADPH oxidase genes (rbohA, rbohB, rbohC, rbohD) and total activity of NOX enzyme in maize plants were investigated. In addition, inhibitory effect of diphenylene iodonium (DPI) pre-treatment on NOX activity and hydrogen peroxide content in aphid-stressed maize seedlings was studied. Leaf infestation biotests were accomplished on 14-day-old seedlings representing two aphid-resistant varieties (Ambrozja and Waza) and two aphid-susceptible ones (Tasty Sweet and Złota Karłowa). Insects' attack led to profound upregulation of rbohA and rbohD genes in tested host plants, lower elevations were noted in level of rbohB mRNA, whereas abundance of rbohC transcript was not significantly altered. It was uncovered aphid-induced enhancement of NOX activity in examined plants. Higher increases in expression of all investigated rboh genes and activity of NADPH oxidase occurred in tissues of more resistant maize cultivars than in susceptible ones. Furthermore, DPI treatment resulted in strong reduction of NOX activity and H2O2 accumulation in aphid-infested Z. mays plants, thus evidencing circumstantial role of the enzyme in insect-elicited ROS generation. Copyright © 2016 Elsevier Inc. All rights reserved.

  4. Sugarcane Aphid Population Growth, Plant Injury, and Natural Enemies on Selected Grain Sorghum Hybrids in Texas and Louisiana.

    Science.gov (United States)

    Brewer, Michael J; Gordy, John W; Kerns, David L; Woolley, James B; Rooney, William L; Bowling, Robert D

    2017-10-01

    In response to the 2013 outbreak of sugarcane aphid, Melanaphis sacchari (Zehntner) (Hemiptera: Aphididae), on sorghum, Sorghum bicolor (L.), in North America, experiments were conducted at three southern U.S. grain sorghum production locations (Corpus Christi, TX; Winnsboro, LA; Rosenberg, TX). The objectives were to authenticate yield decline on susceptible hybrids (2014 and 2015) and to measure aphid population growth and natural enemy prevalence on susceptible and resistant hybrids with similar genetic background (2014). Yield decline on susceptible hybrids (Tx 2752/Tx430 and DKS53-67) was more substantial when aphid population growth accelerated quickly and peaked above 300 aphids per leaf (50 to nearly 100% yield decline). Location and year variation in maximum aphid density and cumulative aphid-days was high, with doubling time values on the susceptible hybrids ranging between 3.9 and 7.9 d. On resistant Tx2752/Tx2783, leaf injury and yield decline were not seen or less severe than on its paired susceptible Tx2752/Tx430. Aphids declined on Tx2752/Tx2783 after initial colony establishment (Corpus Christi) or took about 60% longer to double in population size when compared with Tx2572/Tx430 (Winnsboro). The predominant natural enemy taxa were aphelinid mummies (Hymenoptera: Aphelinidae), ladybird beetles (Coleoptera: Coccinellidae), and sryphid flies (Diptera: Syrphidae), and they were more prevalent during flowering than prior to flowering. They were generally responsive to changes in aphid density of both susceptible and resistant hybrids, but variability points to need for further study. In future research, full season observations should continue as well as more detailed study of potential compatibility of sorghum resistance and biological control. © The Author 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  5. Study on the reduction and hysteresis effect of soil nitrogen pollution by Alfalfa in channel buffer bank

    Science.gov (United States)

    Chi, Yixia; Xue, Lianqing; Zhang, Zhanyu; Li, Dongying

    2018-01-01

    Based on the simulation experiments of solute transport in channel buffer bank and pot experiments, this study analyzed the transport of nitrogen pollution from farmland drains along the South-North Water Transfer east route project; and compared the nitrogen transport rule and purification effect of alfalfa in channel buffer bank soil under situations of bare land and alfalfa mulching. The results showed that: (1) soil nitrogen content decreased gradually with the width increase of channel buffer bank by the soil adsorption and decomposition; (2) the migration rates of nitrogen were 0.06 g·kg-1 by the alfalfa mulching; (3) the removed rates of nitrogen from the soil were 0.088 g·kg-1 by cutting alfalfa; (4) the residual nitrogen of soil with alfalfa was 10% of the bare land. Alfalfa in channel buffer bank had obvious reduction and hysteresis effect to soil nitrogen pollution.

  6. Characterization of Arabidopsis Transcriptional Responses to Different Aphid Species Reveals Genes that Contribute to Host Susceptibility and Non-host Resistance

    Science.gov (United States)

    Jaouannet, Maëlle; Morris, Jenny A.; Hedley, Peter E.; Bos, Jorunn I. B.

    2015-01-01

    Aphids are economically important pests that display exceptional variation in host range. The determinants of diverse aphid host ranges are not well understood, but it is likely that molecular interactions are involved. With significant progress being made towards understanding host responses upon aphid attack, the mechanisms underlying non-host resistance remain to be elucidated. Here, we investigated and compared Arabidopsis thaliana host and non-host responses to aphids at the transcriptional level using three different aphid species, Myzus persicae, Myzus cerasi and Rhopalosiphum pisum. Gene expression analyses revealed a high level of overlap in the overall gene expression changes during the host and non-host interactions with regards to the sets of genes differentially expressed and the direction of expression changes. Despite this overlap in transcriptional responses across interactions, there was a stronger repression of genes involved in metabolism and oxidative responses specifically during the host interaction with M. persicae. In addition, we identified a set of genes with opposite gene expression patterns during the host versus non-host interactions. Aphid performance assays on Arabidopsis mutants that were selected based on our transcriptome analyses identified novel genes contributing to host susceptibility, host defences during interactions with M. persicae as well to non-host resistance against R. padi. Understanding how plants respond to aphid species that differ in their ability to infest plant species, and identifying the genes and signaling pathways involved, is essential for the development of novel and durable aphid control in crop plants. PMID:25993686

  7. Impurities in alfalfa seed and their impact on processing technology

    OpenAIRE

    Đokić, Dragoslav; Stanisavljević, Rade; Marković, Jordan; Terzić, Dragan; Anđelković, Bojan

    2012-01-01

    The aim of this research was to determine relevant parameters and optimal alfalfa seed processing technology by a comparative analysis of two systems of machinery for processing natural alfalfa seed of different purity (59.0% and 71.0%) and with different content of impurities. The relevant parameters monitored during the test were: pure seed (%), weed seeds and seeds of other crops (%), inert matter (%), amount of processed seed (kg), seed processing time (min), consumption of steel powder (...

  8. Multiple centroid method to evaluate the adaptability of alfalfa genotypes

    Directory of Open Access Journals (Sweden)

    Moysés Nascimento

    2015-02-01

    Full Text Available This study aimed to evaluate the efficiency of multiple centroids to study the adaptability of alfalfa genotypes (Medicago sativa L.. In this method, the genotypes are compared with ideotypes defined by the bissegmented regression model, according to the researcher's interest. Thus, genotype classification is carried out as determined by the objective of the researcher and the proposed recommendation strategy. Despite the great potential of the method, it needs to be evaluated under the biological context (with real data. In this context, we used data on the evaluation of dry matter production of 92 alfalfa cultivars, with 20 cuttings, from an experiment in randomized blocks with two repetitions carried out from November 2004 to June 2006. The multiple centroid method proved efficient for classifying alfalfa genotypes. Moreover, it showed no unambiguous indications and provided that ideotypes were defined according to the researcher's interest, facilitating data interpretation.

  9. [Determination of Hard Rate of Alfalfa (Medicago sativa L.) Seeds with Near Infrared Spectroscopy].

    Science.gov (United States)

    Wang, Xin-xun; Chen, Ling-ling; Zhang, Yun-wei; Mao, Pei-sheng

    2016-03-01

    Alfalfa (Medicago sativa L.) is the most commonly grown forage crop due to its better quality characteristics and high adaptability in China. However, there was 20%-80% hard seeds in alfalfa which could not be identified easily from non hard seeds which would cause the loss of seed utilization value and plant production. This experiment was designed for 121 samples of alfalfa. Seeds were collected according to different regions, harvested year and varieties. 31 samples were artificial matched as hard rates ranging from 20% to 80% to establish a model for hard seed rate by near infrared spectroscopy (NIRS) with Partial Least Square (PLS). The objective of this study was to establish a model and to estimate the efficiency of NIRS for determining hard rate of alfalfa seeds. The results showed that the correlation coefficient (R2(cal)) of calibration model was 0.981 6, root mean square error of cross validation (RMSECV) was 5.32, and the ratio of prediction to deviation (RPD) was 3.58. The forecast model in this experiment presented the satisfied precision. The proposed method using NIRS technology is feasible for identification and classification of hard seed in alfalfa. A new method, as nondestructive testing of hard seed rate, was provided to theoretical basis for fast nondestructive detection of hard seed rates in alfalfa.

  10. Alfalfa nutritive quality for ruminant livestock as influenced by ambient air quality in west-central Alberta

    International Nuclear Information System (INIS)

    Lin, J.C.; Nosal, M.; Muntifering, R.B.; Krupa, S.V.

    2007-01-01

    Alfalfa (Medicago sativa) nutritive quality response to ambient ozone (O 3 ), sulfur dioxide (SO 2 ) and oxides of nitrogen (NO x ) were assessed at three locations in west-central Alberta, Canada (1998-2002). Yield data were segregated into high and low relative to overall median yield. Ozone concentrations (hourly median and 95th-percentile) and precipitation (P) contributed 69 and 29%, respectively, to the variability in crude protein (CP) concentration in low-yielding alfalfa, whereas mean temperature (T) and relative humidity (RH) collectively influenced 98% of the variation in CP in high-yielding alfalfa. Three-fourths of the accounted variation in relative feed value (RFV) of low-yielding alfalfa was attributable to P, T and RH, whereas median and 95th-percentile hourly O 3 concentrations and SO 2 and NO x exposure integrals contributed 25%. In contrast, air quality, (mainly O 3 ) influenced 86% of the accounted variation in RFV of high-yielding alfalfa, and T and P collectively contributed 14%. - Exposure to ambient concentrations of phytotoxic air pollutants affected nutritive quality of alfalfa for ruminant livestock in a yield-dependent manner

  11. Water savings from reduced alfalfa cropping in California's Upper San Joaquin Valley

    Science.gov (United States)

    Singh, K. K.; Gray, J.

    2017-12-01

    Water and food and forage security are inextricably linked. In fact, 90% of global freshwater is consumed for food production. Food demand increases as populations grow and diets change, making water increasingly scarce. This tension is particularly acute, contentious, and popularly appreciated in California's Central Valley, which is one of the most important non-grain cropping areas in the United States. While the water-intensive production of tree nuts like almonds and pistachios has received the most popular attention, it is California's nation-leading alfalfa production that consumes the most water. Alfalfa, the "Queen of Forages" is the preferred feedstock for California's prodigious dairy industry. It is grown year-round, and single fields can be harvested more than four times a year; a practice which can require in excess of 1.5 m of irrigation water. Given the water scarcity in the region, the production of alfalfa is under increasing scrutiny with respect to long-term sustainability. However, the potential water savings associated with alternative crops, and various levels of alfalfa replacement have not been quantified. Here, we address that knowledge gap by simulating the ecohydrology of the Upper San Joaquin's cropping system under various scenarios of alfalfa crop replacement with crops of comparable economic value. Specifically, we use the SWAT model to evaluate the water savings that would be realized at 33%, 66%, and 100% alfalfa replacement with economically comparable, but more water efficient crops such as tomatoes. Our results provide an important quantification of the potential water savings under alternative cropping systems that, importantly, also addresses the economic concerns of farmers. Results like these provide critical guidance to farmers and land/water decision makers as they plan for a more sustainable and productive agricultural future.

  12. The radiosensitivity of alfalfa varieties and the fuzzy concentration analysis

    International Nuclear Information System (INIS)

    Kang Yufan; Ma Helin

    1994-09-01

    The dried alfalfa seeds (12.1% moisture) were exposed to 6 '0Co γ radiation field with 0∼36.1 C/kg radiation doses (irradiation rate is 2.84 x 10 -2 C/(kg·min)) to observe and measure some radio-bio-effectivity. In the range of irradiation doses, vitality index, root length, seedling survival rate, seedling height, plant height and grass yield decreased and pollen sterility, micro-nucleus rate, free radical relative content increased as the amount of radiation increased. The activity of peroxidase increased as the amount of radiation increased within certain range of dose and tended to decreased beyond that range. Vitality index and root length, which dosage effect curve is compatible with multiple targets-single hit model, and seedling survival rate, seedling height, plant height and grass yield, which dosage effect curve is compatible with linear regression model. There were strong co-relations between the seedling height, micro-nucleus cell rate and the free radical relative content (P<0.01). There were very significant difference (P<0.01) between the alfalfa species and varieties. With fuzzy concentration analysis method, the alfalfa sample were classified into five groups: higher sensitive, sensitive, intermediate, resistant, higher resistant. The suitable irradiation doses for the alfalfa species and varieties are between 12.9∼34.8 mCi/kg

  13. VizieR Online Data Catalog: HI-bearing ultra-diffuse ALFALFA galaxies (Leisman+, 2017)

    Science.gov (United States)

    Leisman, L.; Haynes, M. P.; Janowiecki, S.; Hallenbeck, G.; Jozsa, G.; Giovanelli, R.; Adams, E. A. K.; Neira, D. B.; Cannon, J. M.; Janesh, W. F.; Rhode, K. L.; Salzer, J. J.

    2018-02-01

    All sources discussed here have available SDSS and ALFALFA data. The ALFALFA observations, data reduction, and catalog products are detailed elsewhere (e.g., Giovanelli+ 2005AJ....130.2598G ; Saintonge 2007AJ....133.2087S ; Haynes+ 2011, J/AJ/142/170). (1 data file).

  14. Expression of the Galanthus nivalis agglutinin (GNA) gene in transgenic potato plants confers resistance to aphids.

    Science.gov (United States)

    Mi, Xiaoxiao; Liu, Xue; Yan, Haolu; Liang, Lina; Zhou, Xiangyan; Yang, Jiangwei; Si, Huaijun; Zhang, Ning

    2017-01-01

    Aphids, the largest group of sap-sucking pests, cause significant yield losses in agricultural crops worldwide every year. The massive use of pesticides to combat this pest causes severe damage to the environment, putting in risk the human health. In this study, transgenic potato plants expressing Galanthus nivalis agglutinin (GNA) gene were developed using CaMV 35S and ST-LS1 promoters generating six transgenic lines (35S1-35S3 and ST1-ST3 corresponding to the first and second promoter, respectively). Quantitative real-time polymerase chain reaction (qRT-PCR) analysis indicated that the GNA gene was expressed in leaves, stems and roots of transgenic plants under the control of the CaMV 35S promoter, while it was only expressed in leaves and stems under the control of the ST-LS1 promoter. The levels of aphid mortality after 5 days of the inoculation in the assessed transgenic lines ranged from 20 to 53.3%. The range of the aphid population in transgenic plants 15 days after inoculation was between 17.0±1.43 (ST2) and 36.6±0.99 (35S3) aphids per plant, which corresponds to 24.9-53.5% of the aphid population in non-transformed plants. The results of our study suggest that GNA expressed in transgenic potato plants confers a potential tolerance to aphid attack, which appears to be an alternative against the use of pesticides in the future. Copyright © 2016 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  15. Alfalfa dodder (Cuscuta campestris) toxicity in horses: clinical, haematological and serum biochemical findings.

    Science.gov (United States)

    Abutarbush, S M

    2013-07-27

    The objective of this observational study is to describe clinical, haematological and serum biochemical findings of horses affected with alfalfa dodder (Cuscuta campestris) toxicity. Twenty horses naturally exposed to alfalfa dodder toxicity were examined and information was collected on history and clinical signs. Physical examination was done on horses in the premises (n=20), and venous blood samples of 12 horses were submitted for haematology and serum biochemical examination for each horse. Abnormal clinical signs started around 36 hours after horses were fed the contaminated alfalfa. Abnormal signs were seen in 11 horses and those included diarrhoea (n=8), decreased appetite (n=7), neurological signs (n=4) and abdominal pain (n=1). Some horses had multiple clinical signs of the above. The results of complete blood cell count revealed leukocytopenia, neutropenia and thrombocytopenia. Serum biochemical analysis revealed decreased ALP, AST and CPK levels and increased direct bilirubin level. The used alfalfa was stopped immediately and a different alfalfa from a new container that did not contain any weeds was fed. Horses on the premises were observed closely, and the abnormal clinical signs resolved within three days. No treatment was implemented. Knowledge about toxicity of horses by Cuscuta species is scarce in the English veterinary literature and very limited.

  16. Transgenic Alfalfa Plants Expressing the Sweetpotato Orange Gene Exhibit Enhanced Abiotic Stress Tolerance

    Science.gov (United States)

    Wang, Zhi; Ke, Qingbo; Kim, Myoung Duck; Kim, Sun Ha; Ji, Chang Yoon; Jeong, Jae Cheol; Lee, Haeng-Soon; Park, Woo Sung; Ahn, Mi-Jeong; Li, Hongbing; Xu, Bingcheng; Deng, Xiping; Lee, Sang-Hoon; Lim, Yong Pyo; Kwak, Sang-Soo

    2015-01-01

    Alfalfa (Medicago sativa L.), a perennial forage crop with high nutritional content, is widely distributed in various environments worldwide. We recently demonstrated that the sweetpotato Orange gene (IbOr) is involved in increasing carotenoid accumulation and enhancing resistance to multiple abiotic stresses. In this study, in an effort to improve the nutritional quality and environmental stress tolerance of alfalfa, we transferred the IbOr gene into alfalfa (cv. Xinjiang Daye) under the control of an oxidative stress-inducible peroxidase (SWPA2) promoter through Agrobacterium tumefaciens-mediated transformation. Among the 11 transgenic alfalfa lines (referred to as SOR plants), three lines (SOR2, SOR3, and SOR8) selected based on their IbOr transcript levels were examined for their tolerance to methyl viologen (MV)-induced oxidative stress in a leaf disc assay. The SOR plants exhibited less damage in response to MV-mediated oxidative stress and salt stress than non-transgenic plants. The SOR plants also exhibited enhanced tolerance to drought stress, along with higher total carotenoid levels. The results suggest that SOR alfalfa plants would be useful as forage crops with improved nutritional value and increased tolerance to multiple abiotic stresses, which would enhance the development of sustainable agriculture on marginal lands. PMID:25946429

  17. Transmission of Turnip yellows virus by Myzus persicae Is Reduced by Feeding Aphids on Double-Stranded RNA Targeting the Ephrin Receptor Protein

    Directory of Open Access Journals (Sweden)

    Michaël Mulot

    2018-03-01

    Full Text Available Aphid-transmitted plant viruses are a threat for major crops causing massive economic loss worldwide. Members in the Luteoviridae family are transmitted by aphids in a circulative and non-replicative mode. Virions are acquired by aphids when ingesting sap from infected plants and are transported through the gut and the accessory salivary gland (ASG cells by a transcytosis mechanism relying on virus-specific receptors largely unknown. Once released into the salivary canal, virions are inoculated to plants, together with saliva, during a subsequent feeding. In this paper, we bring in vivo evidence that the membrane-bound Ephrin receptor (Eph is a novel aphid protein involved in the transmission of the Turnip yellows virus (TuYV, Polerovirus genus, Luteoviridae family by Myzus persicae. The minor capsid protein of TuYV, essential for aphid transmission, was able to bind the external domain of Eph in yeast. Feeding M. persicae on in planta- or in vitro-synthesized dsRNA targeting Eph-mRNA (dsRNAEph did not affect aphid feeding behavior but reduced accumulation of TuYV genomes in the aphid's body. Consequently, TuYV transmission efficiency by the dsRNAEph-treated aphids was reproducibly inhibited and we brought evidence that Eph is likely involved in intestinal uptake of the virion. The inhibition of virus uptake after dsRNAEph acquisition was also observed for two other poleroviruses transmitted by M. persicae, suggesting a broader role of Eph in polerovirus transmission. Finally, dsRNAEph acquisition by aphids did not affect nymph production. These results pave the way toward an ecologically safe alternative of insecticide treatments that are used to lower aphid populations and reduce polerovirus damages.

  18. Transmission of Turnip yellows virus by Myzus persicae Is Reduced by Feeding Aphids on Double-Stranded RNA Targeting the Ephrin Receptor Protein.

    Science.gov (United States)

    Mulot, Michaël; Monsion, Baptiste; Boissinot, Sylvaine; Rastegar, Maryam; Meyer, Sophie; Bochet, Nicole; Brault, Véronique

    2018-01-01

    Aphid-transmitted plant viruses are a threat for major crops causing massive economic loss worldwide. Members in the Luteoviridae family are transmitted by aphids in a circulative and non-replicative mode. Virions are acquired by aphids when ingesting sap from infected plants and are transported through the gut and the accessory salivary gland (ASG) cells by a transcytosis mechanism relying on virus-specific receptors largely unknown. Once released into the salivary canal, virions are inoculated to plants, together with saliva, during a subsequent feeding. In this paper, we bring in vivo evidence that the membrane-bound Ephrin receptor (Eph) is a novel aphid protein involved in the transmission of the Turnip yellows virus (TuYV, Polerovirus genus, Luteoviridae family) by Myzus persicae . The minor capsid protein of TuYV, essential for aphid transmission, was able to bind the external domain of Eph in yeast. Feeding M. persicae on in planta - or in vitro -synthesized dsRNA targeting Eph -mRNA (dsRNA Eph ) did not affect aphid feeding behavior but reduced accumulation of TuYV genomes in the aphid's body. Consequently, TuYV transmission efficiency by the dsRNA Eph -treated aphids was reproducibly inhibited and we brought evidence that Eph is likely involved in intestinal uptake of the virion. The inhibition of virus uptake after dsRNA Eph acquisition was also observed for two other poleroviruses transmitted by M. persicae , suggesting a broader role of Eph in polerovirus transmission. Finally, dsRNA Eph acquisition by aphids did not affect nymph production. These results pave the way toward an ecologically safe alternative of insecticide treatments that are used to lower aphid populations and reduce polerovirus damages.

  19. Neozygites osornensis sp. nov., a fungal species causing mortality to the cypress aphid Cinara cupressi in Chile.

    Science.gov (United States)

    Retamal, Cristian Montalva; Barta, Marek; Pérez, Eladio Rojas; Flores, Eduardo Valenzuela

    2013-01-01

    An entomophthoralean fungus causing epizootics in populations of the cypress aphid, Cinara cupressi Buckton, in Chile is described as a new species, Neozygites osornensis Montalva et Barta. The aphid pathogen is described based on morphological characters. An exhaustive description, illustrations and a comparison with closely related species are provided. The fungus differs from similar Neozygites species by smaller hyphal bodies, nuclei, primary conidia, capilliconidia and capilliphores and by noticeably different shape of capilliconidia. A key to aphid-pathogenic species of Neozygites is also included.

  20. Aphid parasitoids (Hymenoptera, Braconidae, Aphidiinae) from Thailand

    Czech Academy of Sciences Publication Activity Database

    Starý, Petr; Rakhshani, E.; Tomanović, Ž.; Kavallieratos, N. G.; Sharkey, M.

    -, č. 2498 (2010), s. 47-52 ISSN 1175-5326 Grant - others:Ministry of Science of the Republic of Serbia(CS) 143006B; U. S. National Science Foundation(US) DEB 0542864 Institutional research plan: CEZ:AV0Z50070508 Keywords : aphids * parasitoids * biodiversity Subject RIV: EG - Zoology Impact factor: 0.853, year: 2010

  1. World Epidemiology Review, Number 105.

    Science.gov (United States)

    1978-09-13

    respectively last year. Not Siberian The official stated that the Soviet virus is not related to the famous pathogenic agent which appeared in the Siberian...numbers of aphids are due to appear on the alfalfa in the near future. The infestation has approached and even exceeded the extent at which serious

  2. Occurrence of alfalfa (Medicago sativa L.) populations along roadsides in southern Manitoba, Canada and their potential role in intraspecific gene flow.

    Science.gov (United States)

    Bagavathiannan, Muthukumar V; Gulden, Robert H; Van Acker, Rene C

    2011-04-01

    Alfalfa is a highly outcrossing perennial species that can be noticed in roadsides as feral populations. There remains little information available on the extent of feral alfalfa populations in western Canadian prairies and their role in gene flow. The main objectives of this study were (a) to document the occurrence of feral alfalfa populations, and (b) to estimate the levels of outcrossing facilitated by feral populations. A roadside survey confirmed widespread occurrence of feral alfalfa populations, particularly in alfalfa growing regions. The feral populations were dynamic and their frequency ranged from 0.2 to 1.7 populations km(-1). In many cases, the nearest feral alfalfa population from alfalfa production field was located within a distance sufficient for outcrossing in alfalfa. The gene flow study confirmed that genes can move back and forth between feral and cultivated alfalfa populations. In this study, the estimated outcrossing levels were 62% (seed fields to feral), 78% (feral to seed fields), 82% (hay fields to feral) and 85% (feral to feral). Overall, the results show that feral alfalfa plants are prevalent in alfalfa producing regions in western Canada and they can serve as bridges for gene flow at landscape level. Management of feral populations should be considered, if gene flow is a concern. Emphasis on preventing seed spill/escapes and intentional roadside planting of alfalfa cultivars will be particularly helpful. Further, realistic and pragmatic threshold levels should be established for markets sensitive to the presence of GE traits.

  3. Easy synthesis of graphene sheets from alfalfa plants by treatment of nitric acid

    International Nuclear Information System (INIS)

    Qu, Jiao; Luo, Chunqiu; Zhang, Qian; Cong, Qiao; Yuan, Xing

    2013-01-01

    Highlights: ► An easy method for synthesis of graphene sheets using alfalfa plants was introduced. ► An novelty formation mechanism of graphene sheets using alfalfa plants was proposed. ► This method exploits a new carbon source and provides a novel idea to synthesize graphene sheets. -- Abstract: This letter focuses on synthesis of graphene sheets from alfalfa plants by treatment of nitric acid. The transmission electron microscopy image (TEM) demonstrates that the graphene sheets are agglomerated and overlapped, the energy dispersive spectrum (EDS) indicates that the products are pure, and the Raman spectrum shows the graphene sheets are well graphitized. In addition, the formation mechanism of the graphene sheets from alfalfa plants by treatment nitric acid is discussed. These findings inspire the search for a new strategy for synthesis of graphene sheets from renewable natural products, and the lower cost of this new process and carbon source may facilitate industrial production

  4. Easy synthesis of graphene sheets from alfalfa plants by treatment of nitric acid

    Energy Technology Data Exchange (ETDEWEB)

    Qu, Jiao, E-mail: qujiao@bhu.edu.cn [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China); Luo, Chunqiu, E-mail: fplj_lcq@163.com [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Zhang, Qian; Cong, Qiao [School of Chemistry and Chemical Engineering, Bohai University, Jinzhou 121013 (China); Yuan, Xing [School of Urban and Environmental Sciences, Northeast Normal University, Changchun 130024 (China)

    2013-04-01

    Highlights: ► An easy method for synthesis of graphene sheets using alfalfa plants was introduced. ► An novelty formation mechanism of graphene sheets using alfalfa plants was proposed. ► This method exploits a new carbon source and provides a novel idea to synthesize graphene sheets. -- Abstract: This letter focuses on synthesis of graphene sheets from alfalfa plants by treatment of nitric acid. The transmission electron microscopy image (TEM) demonstrates that the graphene sheets are agglomerated and overlapped, the energy dispersive spectrum (EDS) indicates that the products are pure, and the Raman spectrum shows the graphene sheets are well graphitized. In addition, the formation mechanism of the graphene sheets from alfalfa plants by treatment nitric acid is discussed. These findings inspire the search for a new strategy for synthesis of graphene sheets from renewable natural products, and the lower cost of this new process and carbon source may facilitate industrial production.

  5. Effect of Arbuscular Mycorrhizal Fungi Glomus spp. Inoculation on Alfalfa Growth in Soils with Copper Efecto de la Inoculación con Hongos Micorrízicos Arbusculares Glomus spp. sobre el Crecimiento de Alfalfa en Suelos con Cobre

    Directory of Open Access Journals (Sweden)

    Daniela Novoa M

    2010-06-01

    Full Text Available Soils near mining centers usually have high heavy metal (HM levels. It has been found that some plants associated with arbuscular mycorrhizal fungi (AMF improve growth and tolerance to HM in soils. This symbiosis is a biological resource for degraded soil recovery. The objective of this study was to determine the effect of inoculating AMF (Glomus spp. on alfalfa (Medicago sativa L. growth in agricultural soils with different copper (Cu levels for degraded soil recovery. To this effect, alfalfa seeds were grown in soils from the Catemu and Casablanca valleys and inoculated with AMF. Plant height, stem diameter, and number of leaves were measured weekly. Dry matter, mycorrhizal colonization, and Cu concentration in alfalfa plant tissues were measured after 81 days. Inoculation increased plant height by 24%, stem diameter by 11%, and number of leaves by 34%. Inoculation had a significant effect (p ≤ 0.05 on alfalfa plants that were grown in soil with the highest Cu concentration, but had no effect on Cu accumulation in alfalfa plant tissues. A direct relationship was observed between Cu accumulation in alfalfa and Cu concentration in soils. It was concluded that alfalfa inoculated with Glomus spp. is applicable to the soil recovery process whenever soil properties can ensure inoculum effectiveness on alfalfa growth, and avoid toxicity by excessive Cu in alfalfa plant tissues.Los suelos cercanos a centros de actividad minera suelen presentar altos niveles de metales pesados (HM. Se ha encontrado que algunas plantas asociadas a hongos micorrízicos arbusculares (AMF mejoran su crecimiento y tolerancia a los HM presentes en los suelos. Esta simbiosis constituye un recurso biológico para la recuperación de suelos degradados. El objetivo de este estudio fue determinar el efecto de la inoculación con AMF (Glomus spp. sobre el crecimiento de alfalfa (Medicago sativa L. en suelos agrícolas con distintos niveles de cobre (Cu para la recuperación de

  6. Polyphyly of the extinct family Oviparosiphidae and its implications for inferring aphid evolution (Hemiptera, Sternorrhyncha.

    Directory of Open Access Journals (Sweden)

    Dagmara Żyła

    Full Text Available Aphidoidea, the so-called "true aphids" are one of the most challenging groups in terms of solving the phylogenetic relationships. Morphology-based analyses were strongly affected by widespread homoplasy, while the molecular-based attempts struggled with the lack of sufficient phylogenetic signal. Despite significant improvements, the higher classification still remains unresolved and rather controversial. However, the use of the fossil record, one of the most valuable sources of information, was mainly limited to calibration of a phylogenetic tree, without a direct inclusion into the analysis. The extinct family Oviparosiphidae has long been considered as the common ancestor of all recent Aphidoidea and it was used as a calibration point in several analyses, but it has been never analyzed in a phylogenetic context. The family has been treated as a monophyletic group purely based on the simultaneous presence of two abdominal structures, ovipositor and siphunculi. However, it has been shown recently that at least one more extinct lineage, present at the same time, was characterized by the same features. For these reasons, we performed a maximum parsimony analysis using morphological data for extinct aphid taxa to prove the monophyly of Oviparosiphidae. Our analysis shows that the presumed ancestor lineage of recent aphids is a polyphyletic group. Our results support the hypothesis of an early Mesozoic rapid radiation of aphids, which led to several different lineages characterized by both ovipositor and siphunculi. The results indicate the necessity of examining the other extinct families, and shows that the diversity of aphids before the Cretaceous Terrestrial Revolution (KTR was higher than expected. Even though there is not enough data to perform a formal analysis, fossils seem to suggest a significant impact of the KTR on aphid diversification. Additionally, we have made a redescription of two genera and description of a new species

  7. Advances in improvement of stress tolerance by induced mutation and genetic transformation in alfalfa

    International Nuclear Information System (INIS)

    Huang Xin; Ye Hongxia; Shu Xiaoli; Wu Dianxing

    2008-01-01

    In order to provide references for stress-tolerant breeding of alfalfa, genetic basis of stress-tolerant traits was briefly introduced and advanced in improvement of stress-tolerance by induced mutation and genetic transformation in alfalfa were reviewed. (authors)

  8. Alfalfa nutritive quality for ruminant livestock as influenced by ambient air quality in west-central Alberta

    Energy Technology Data Exchange (ETDEWEB)

    Lin, J.C. [Department of Animal Sciences, Auburn University, Auburn, AL 36849 (United States); Nosal, M. [Department of Mathematics and Statistics, University of Calgary, Calgary, AB T2N 1N4 (Canada); Muntifering, R.B. [Department of Animal Sciences, Auburn University, Auburn, AL 36849 (United States)]. E-mail: muntirb@auburn.edu; Krupa, S.V. [Department of Plant Pathology, University of Minnesota, St. Paul, MN 55108 (United States)

    2007-09-15

    Alfalfa (Medicago sativa) nutritive quality response to ambient ozone (O{sub 3}), sulfur dioxide (SO{sub 2}) and oxides of nitrogen (NO {sub x} ) were assessed at three locations in west-central Alberta, Canada (1998-2002). Yield data were segregated into high and low relative to overall median yield. Ozone concentrations (hourly median and 95th-percentile) and precipitation (P) contributed 69 and 29%, respectively, to the variability in crude protein (CP) concentration in low-yielding alfalfa, whereas mean temperature (T) and relative humidity (RH) collectively influenced 98% of the variation in CP in high-yielding alfalfa. Three-fourths of the accounted variation in relative feed value (RFV) of low-yielding alfalfa was attributable to P, T and RH, whereas median and 95th-percentile hourly O{sub 3} concentrations and SO{sub 2} and NO {sub x} exposure integrals contributed 25%. In contrast, air quality, (mainly O{sub 3}) influenced 86% of the accounted variation in RFV of high-yielding alfalfa, and T and P collectively contributed 14%. - Exposure to ambient concentrations of phytotoxic air pollutants affected nutritive quality of alfalfa for ruminant livestock in a yield-dependent manner.

  9. Resistance to Cucurbit aphid-borne yellows virus in Melon Accession TGR-1551.

    Science.gov (United States)

    Kassem, Mona A; Gosalvez, Blanca; Garzo, Elisa; Fereres, Alberto; Gómez-Guillamón, Maria Luisa; Aranda, Miguel A

    2015-10-01

    The genetic control of resistance to Cucurbit aphid-borne yellows virus (CABYV; genus Polerovirus, family Luteoviridae) in the TGR-1551 melon accession was studied through agroinoculation of a genetic family obtained from the cross between this accession and the susceptible Spanish cultivar 'Bola de Oro'. Segregation analyses were consistent with the hypothesis that one dominant gene and at least two more modifier genes confer resistance; one of these additional genes is likely present in the susceptible parent 'Bola de Oro'. Local and systemic accumulation of the virus was analyzed in a time course experiment, showing that TGR-1551 resistance was expressed systemically as a significant reduction of virus accumulation compared with susceptible controls, but not locally in agroinoculated cotyledons. In aphid transmission experiments, CABYV inoculation by aphids was significantly reduced in TGR-1551 plants, although the virus was acquired at a similar rate from TGR-1551 as from susceptible plants. Results of feeding behavior studies using the DC electrical penetration graph technique suggested that viruliferous aphids can salivate and feed from the phloem of TGR-1551 plants and that the observed reduction in virus transmission efficiency is not related to reduced salivation by Aphis gossypii in phloem sieve elements. Since the virus is able to accumulate to normal levels in agroinoculated tissues, our results suggest that resistance of TGR-1551 plants to CABYV is related to impairment of virus movement or translocation after it reaches the phloem sieve elements.

  10. Morphological variation of Aphidius ervi Haliday (Hymenoptera: Braconidae associated with different aphid hosts

    Directory of Open Access Journals (Sweden)

    Cinthya M. Villegas

    2017-07-01

    Full Text Available Background Parasitoids are frequently used in biological control due to the fact that they are considered host specific and highly efficient at attacking their hosts. As they spend a significant part of their life cycle within their hosts, feeding habits and life history of their host can promote specialization via host-race formation (sequential radiation. The specialized host races from different hosts can vary morphologically, behaviorally and genetically. However, these variations are sometimes inconspicuous and require more powerful tools in order to detect variation such as geometric morphometrics analysis. Methods We examined Aphidius ervi, an important introduced biological control agent in Chile associated with a great number of aphid species, which are exploiting different plant hosts and habitats. Several combinations (biotypes of parasitoids with various aphid/host plant combinations were analyzed in order to obtain measures of forewing shape and size. To show the differences among defined biotypes, we chose 13 specific landmarks on each individual parasitoid wing. The analysis of allometric variation calculated in wing shape and size over centroid size (CS, revealed the allometric changes among biotypes collected from different hosts. To show all differences in shape of forewings, we made seven biotype pairs using an outline-based geometric morphometrics comparison. Results The biotype A. pis_pea (Acyrthosiphon pisum on pea was the extreme wing size in this study compared to the other analyzed biotypes. Aphid hosts have a significant influence in the morphological differentiation of the parasitoid forewing, splitting biotypes in two groups. The first group consisted of biotypes connected with Acyrthosiphon pisum on legumes, while the second group is composed of biotypes connected with aphids attacking cereals, with the exception of the R. pad_wheat (Rhopalosiphum padi on wheat biotype. There was no significant effect of plant

  11. Transgenic Expression of a Functional Fragment of Harpin Protein Hpa1 in Wheat Represses English Grain Aphid Infestation

    Institute of Scientific and Technical Information of China (English)

    XU Man-yu; ZHOU Ting; ZHAO Yan-ying; LI Jia-bao; XU Heng; DONG Han-song; ZHANG Chun-ling

    2014-01-01

    The harpin protein Hpa1 produced by the rice bacterial blight pathogen promotes plant growth and induces plant resistance to pathogens and insect pests. The region of 10-42 residues (Hpa110-42) in the Hpa1 sequence is critical as the isolated Hpa110-42 fragment is 1.3-7.5-fold more effective than the full length in inducing plant growth and resistance. Here we report that transgenic expression of Hpa110-42 in wheat induces resistance to English grain aphid, a dominant species of wheat aphids. Hpa110-42-induced resistance is effective to inhibit the aphid behavior in plant preference at the initial colonization stage and repress aphid performances in the reproduction, nymph growth, and instar development on transgenic plants. The resistance characters are correlated with enhanced expression of defense-regulatory genes (EIN2, PP2-A, and GSL10) and consistent with induced expression of defense response genes (Hel, PDF1.2, PR-1b, and PR-2b). As a result, aphid infestations are alleviated in transgenic plants. The level of Hpa110-42-induced resistance in regard to repression of aphid infestations is equivalent to the effect of chemical control provided by an insecticide. These results suggested that the defensive role of Hpa110-42 can be integrated into breeding germplasm of the agriculturally signiifcant crop with a great potential of the agricultural application.

  12. Proteomic analysis of Arabidopsis thaliana (L.) Heynh responses to a generalist sucking pest (Myzus persicae Sulzer).

    Science.gov (United States)

    Truong, D-H; Bauwens, J; Delaplace, P; Mazzucchelli, G; Lognay, G; Francis, F

    2015-11-01

    Herbivorous insects can cause severe cellular changes to plant foliage following infestations, depending on feeding behaviour. Here, a proteomic study was conducted to investigate the influence of green peach aphid (Myzus persicae Sulzer) as a polyphagous pest on the defence response of Arabidopsis thaliana (L.) Heynh after aphid colony establishment on the host plant (3 days). Analysis of about 574 protein spots on 2-DE gels revealed 31 differentially expressed protein spots. Twenty out of these 31 differential proteins were selected for analysis by mass spectrometry. In 12 of the 20 analysed spots, we identified seven and nine proteins using MALDI-TOF-MS and LC-ESI-MS/MS, respectively. Of the analysed spots, 25% contain two proteins. Different metabolic pathways were modulated in Arabidopsis leaves according to aphid feeding: most corresponded to carbohydrate, amino acid and energy metabolism, photosynthesis, defence response and translation. This paper has established a survey of early alterations induced in the proteome of Arabidopsis by M. persicae aphids. It provides valuable insights into the complex responses of plants to biological stress, particularly for herbivorous insects with sucking feeding behaviour. © 2015 German Botanical Society and The Royal Botanical Society of the Netherlands.

  13. The effects of alfalfa particle size and acid treated protein on ruminal ...

    African Journals Online (AJOL)

    DR. NJ TONUKARI

    2011-10-17

    Oct 17, 2011 ... received a mixed diet (% of dry matter) consisting of 23.73 alfalfa, 8.70 canola meal, 39.56 wheat straw,. 13.45 beet pulp and 13.45 ... ruminal mean retention time of plastic particles in sheep. (Kaske and Engelhardt .... 13.45 and 13.45% of alfalfa forage, canola meal, wheat straw, beet pulp and barley grain, ...

  14. Yields of alfalfa varieties with different fall dormancy levels in northeast china

    International Nuclear Information System (INIS)

    Chen, J.S.; Zhu, R.F.; Di, G.L.

    2014-01-01

    Fall dormancy (FD) is an important indicator of winter hardiness in alfalfa (Medicago sativa L.), the relationship between FD and the yield potential of alfalfa varieties were investigated to survey annual dry matter (DM) yields with FD levels in the northeast regions with cold winters. During three consecutive years, all varieties of five FD levels survived over the winter without any persistency problems and there were no differences in annual DM yields of varieties among FD levels. Among the same FD varieties, DM yields for some of the dormant, semi-dormant and non-dormant varieties were found no correlated with FD levels. In conclusion, it suggests that different FD levels no effected on yields of alfalfa in the cold regions, such as North-east China. (author)

  15. Comparación de dos índices cuantitativos de estimación del estado de desarrollo de la alfalfa Comparison of two quantitative indexes for the estimation of alfalfa development stages

    Directory of Open Access Journals (Sweden)

    M.L. Bernáldez

    2006-12-01

    Full Text Available El estado de desarrollo de la alfalfa (Medicago sativa L. es una variable de estudio común en evaluaciones de cultivares, dada su relación con la composición química y la tasa de crecimiento de la pastura. La determinación de los índices cuantitativos "estado medio por conteo" y "estado medio por peso" (EMC y EMP respectivamente permite la descripción del estado de desarrollo en pasturas de alfalfa de una manera objetiva y reproducible. Los índices EMC y EMP describen igualmente el estado de desarrollo de la alfalfa cuando la pastura se encuentra próxima al momento de utilización recomendado en la práctica. La ventaja de estimar EMC en relación a EMP, se basa en la rapidez operativa que ofrece la generación de datos para el cálculo del primero.The developmental stage of alfalfa (Medicago sativa L. is an usual variable of study when evaluating cultivars because of its relationship with chemical composition and pasture growth rate. Determination of quantitative indexes such as "mean stage by count" and "mean stage by weight" (MSC and MSW respectively makes it possible to describe the developmental phenological stages of alfalfa pastures in a more objective and reproducible way. Likewise, both the MSC and MSW indexes, describe the developmental stages of alfalfa when the pasture is close to the recommended utilisation time in practice. The advantage of estimating MSC in relation to MSW is based on the higher operative efficiency offered by the former in data generation for its calculation.

  16. Alfalfa (Medicago sativa L.) forage production, tissue and soil nutrient concentration under three N based broiler litter regimes

    Science.gov (United States)

    Alfalfa (Medicago sativa L.) is considered as most important forage legume grown in Kentucky. Alfalfa supports many livestock production systems including the beef, dairy, and horse industries in Kentucky. Being a legume, alfalfa typically meets its N requirement through symbiotic N2 fixation, but h...

  17. Alteration of intersubunit acid–base pair interactions at the quasi-threefold axis of symmetry of Cucumber mosaic virus disrupts aphid vector transmission

    International Nuclear Information System (INIS)

    Bricault, Christine A.; Perry, Keith L.

    2013-01-01

    In the atomic model of Cucumber mosaic virus (CMV), six amino acid residues form stabilizing salt bridges between subunits of the asymmetric unit at the quasi-threefold axis of symmetry. To evaluate the effects of these positions on virion stability and aphid vector transmissibility, six charged amino acid residues were individually mutated to alanine. All of the six engineered viruses were viable and exhibited near wild type levels of virion stability in the presence of urea. Aphid vector transmissibility was nearly or completely eliminated in the case of four of the mutants; two mutants demonstrated intermediate aphid transmissibility. For the majority of the engineered mutants, second-site mutations were observed following aphid transmission and/or mechanical passaging, and one restored transmission rates to that of the wild type. CMV capsids tolerate disruption of acid–base pairing interactions at the quasi-threefold axis of symmetry, but these interactions are essential for maintaining aphid vector transmissibility. - Highlights: ► Amino acids between structural subunits of Cucumber mosaic virus affect vector transmission. ► Mutant structural stability was retained, while aphid vector transmissibility was disrupted. ► Spontaneous, second-site mutations restored aphid vector transmissibility

  18. Alteration of intersubunit acid–base pair interactions at the quasi-threefold axis of symmetry of Cucumber mosaic virus disrupts aphid vector transmission

    Energy Technology Data Exchange (ETDEWEB)

    Bricault, Christine A. [Department of Plant Pathology and Plant-Microbe Biology, 334 Plant Science Building, Cornell University, Ithaca, NY 14850 (United States); Perry, Keith L., E-mail: KLP3@cornell.edu [Department of Plant Pathology and Plant-Microbe Biology, 334 Plant Science Building, Cornell University, Ithaca, NY 14850 (United States)

    2013-06-05

    In the atomic model of Cucumber mosaic virus (CMV), six amino acid residues form stabilizing salt bridges between subunits of the asymmetric unit at the quasi-threefold axis of symmetry. To evaluate the effects of these positions on virion stability and aphid vector transmissibility, six charged amino acid residues were individually mutated to alanine. All of the six engineered viruses were viable and exhibited near wild type levels of virion stability in the presence of urea. Aphid vector transmissibility was nearly or completely eliminated in the case of four of the mutants; two mutants demonstrated intermediate aphid transmissibility. For the majority of the engineered mutants, second-site mutations were observed following aphid transmission and/or mechanical passaging, and one restored transmission rates to that of the wild type. CMV capsids tolerate disruption of acid–base pairing interactions at the quasi-threefold axis of symmetry, but these interactions are essential for maintaining aphid vector transmissibility. - Highlights: ► Amino acids between structural subunits of Cucumber mosaic virus affect vector transmission. ► Mutant structural stability was retained, while aphid vector transmissibility was disrupted. ► Spontaneous, second-site mutations restored aphid vector transmissibility.

  19. Invertebrate communities in spring wheat and the identification of cereal aphid predators through molecular gut content analysis

    Science.gov (United States)

    Cereal aphid complexes are responsible for reducing wheat production worldwide; however, management against these species is rare in North America. Generalist predators may contribute to reducing cereal aphid numbers and preventing significant damage to crops. A two-year survey identifying the arth...

  20. Changes in the free amino acid composition of Capsicum annuum (pepper) leaves in response to Myzus persicae (green peach aphid) infestation. A comparison with water stress.

    Science.gov (United States)

    Florencio-Ortiz, Victoria; Sellés-Marchart, Susana; Zubcoff-Vallejo, José; Jander, Georg; Casas, José L

    2018-01-01

    Amino acids play a central role in aphid-plant interactions. They are essential components of plant primary metabolism, function as precursors for the synthesis of defense-related specialized metabolites, and are major growth-limiting nutrients for aphids. To quantify changes in the free amino acid content of pepper (Capsicum annuum L.) leaves in response to green peach aphid (Myzus persicae Sulzer) feeding, plants were infested with a low (20 aphids/plant) or a high (200 aphids/plant) aphid density in time-course experiments ranging from 3 hours to 7 days. A parallel experiment was conducted with pepper plants that had been subjected to water stress. Factor Analysis of Mixed Data revealed a significant interaction of time x density in the free amino acid response of aphid-infested leaves. At low aphid density, M. persicae did not trigger a strong response in pepper leaves. Conversely, at high density, a large increase in total free amino acid content was observed and specific amino acids peaked at different times post-infestation. Comparing aphid-infested with water-stressed plants, most of the observed differences were quantitative. In particular, proline and hydroxyproline accumulated dramatically in response to water stress, but not in response to aphid infestation. Some additional differences and commonalities between the two stress treatments are discussed.

  1. Short Communication: Occurrence of the pea aphid, Acyrthosiphon ...

    African Journals Online (AJOL)

    The occurrence of pea aphid, Acyrthosiphon pisum (Harris) (Homoptera: Aphididae), on wild annual and perennial leguminous plants was studied at two locations (Adet and Wondata) in West Gojam, Ethiopia in 1999/2000 seasons. Annual and perennial leguminous wild or volunteer plants encountered in the study areas ...

  2. Development and characterization of the first infectious clone of alfalfa latent virus, a strain of Pea streak virus

    Science.gov (United States)

    Alfalfa (Medicago sativa) is a natural host plant for many plant pathogens including fungi, bacteria, nematodes and viruses. Alfalfa latent virus (ALV) is a member of the carlavirus group and occurs symptomlessly in alfalfa. The first complete genomic sequence of the ALV that was recently obtained i...

  3. Screening of Cd tolerant genotypes and isolation of metallothionein genes in alfalfa (Medicago sativa L.)

    International Nuclear Information System (INIS)

    Wang Xiaojuan; Song, Yu; Ma Yanhua; Zhuo Renying; Jin Liang

    2011-01-01

    In order to evaluate Cd tolerance in wide-ranging sources of alfalfa (Medicago sativa) and to identify Cd tolerant genotypes which may potentially be useful for restoring Cd-contaminated environments, thirty-six accessions of alfalfa were screened under hydroponic culture. Our results showed that the relative root growth rate varied from 0.48 to 1.0, which indicated that different alfalfa accessions had various responses to Cd stress. The candidate fragments derived from differentially expressed metallothionein (MT) genes were cloned from leaves of two Cd tolerant genotypes, YE and LZ. DNA sequence and the deduced protein sequence showed that MsMT2a and MsMT2b had high similarity to those in leguminous plants. DDRT-PCR analysis showed that MsMT2a expressed in both YE and LZ plants under control and Cd stress treatment, but MsMT2b only expressed under Cd stress treatment. This suggested that MsMT2a was universally expressed in leaves of alfalfa but expression of MsMT2b was Cadmium (Cd) inducible. - Highlights: → Evaluate Cd tolerance in wide sources of alfalfa accessions. → Identify Cd-hyperaccumulators potentially useful for restoring Cd-contaminated environments. → Cloned differentially expressed metallothionein (MT) genes. → Characteristics and deduced protein sequence of MsMT2a and MsMT2b were analyzed. → MsMT2a might be a universally gene of alfalfa but MsMT2b might be an inductive gene. - Two Cd tolerant alfalfa genotypes were screened and their metallothionein genes were cloned which showed that MsMT2a was universally expressed but MsMT2b was Cd inducible expression.

  4. Screening of Cd tolerant genotypes and isolation of metallothionein genes in alfalfa (Medicago sativa L.)

    Energy Technology Data Exchange (ETDEWEB)

    Wang Xiaojuan, E-mail: xiaojuanwang@lzu.edu.cn [School of Pastoral Agriculture Science and Technology, Lanzhou University, P.O. Box 61, Lanzhou 730020 (China); Song, Yu [School of Pastoral Agriculture Science and Technology, Lanzhou University, P.O. Box 61, Lanzhou 730020 (China); Environment Management College of China, Qinhuangdao 066004 (China); Ma Yanhua [Hebei Normal University of Science and Technology, Qinhuangdao 066004 (China); Zhuo Renying [Key Lab of Tree Genomics, Research Institute of Subtropical of Forest, Chinese Academy of Forest, Fuyang 311400 (China); Jin Liang [School of Pastoral Agriculture Science and Technology, Lanzhou University, P.O. Box 61, Lanzhou 730020 (China)

    2011-12-15

    In order to evaluate Cd tolerance in wide-ranging sources of alfalfa (Medicago sativa) and to identify Cd tolerant genotypes which may potentially be useful for restoring Cd-contaminated environments, thirty-six accessions of alfalfa were screened under hydroponic culture. Our results showed that the relative root growth rate varied from 0.48 to 1.0, which indicated that different alfalfa accessions had various responses to Cd stress. The candidate fragments derived from differentially expressed metallothionein (MT) genes were cloned from leaves of two Cd tolerant genotypes, YE and LZ. DNA sequence and the deduced protein sequence showed that MsMT2a and MsMT2b had high similarity to those in leguminous plants. DDRT-PCR analysis showed that MsMT2a expressed in both YE and LZ plants under control and Cd stress treatment, but MsMT2b only expressed under Cd stress treatment. This suggested that MsMT2a was universally expressed in leaves of alfalfa but expression of MsMT2b was Cadmium (Cd) inducible. - Highlights: > Evaluate Cd tolerance in wide sources of alfalfa accessions. > Identify Cd-hyperaccumulators potentially useful for restoring Cd-contaminated environments. > Cloned differentially expressed metallothionein (MT) genes. > Characteristics and deduced protein sequence of MsMT2a and MsMT2b were analyzed. > MsMT2a might be a universally gene of alfalfa but MsMT2b might be an inductive gene. - Two Cd tolerant alfalfa genotypes were screened and their metallothionein genes were cloned which showed that MsMT2a was universally expressed but MsMT2b was Cd inducible expression.

  5. Interaction of bale size and preservative rate for large-round bales of alfalfa hay

    Science.gov (United States)

    Recently, two studies conducted at the US Dairy Forage Research Center have reported inconsistent storage responses following the application of propionic-acid-based preservatives to alfalfa or alfalfa-orchardgrass hays. One of these studies utilized 5-foot-diameter round bales, and produced disappo...

  6. Polychlorinated biphenyls in alfalfa: Accumulation, sorption and speciation in different plant parts.

    Science.gov (United States)

    Teng, Ying; Sun, Xianghui; Zhu, Lingjia; Christie, Peter; Luo, Yongming

    2017-08-03

    The accumulation, chemical speciation and distribution of polychlorinated biphenyls (PCBs) were investigated in various parts of alfalfa. Moreover, the adsorption characteristics for PCB 28 by alfalfa and the influencing factors of the adsorption characteristics were studied. There were different degrees of PCB accumulation in alfalfa roots, root nodules and shoots. The decreasing order of the accumulation of PCBs in plant tissues was root nodules > roots > shoots, and the decreasing order of the total PCB contents was roots > shoots > root nodules, indicating that the roots were the main sink for PCB accumulation. There were three modes of PCB speciation in alfalfa roots and root nodules, comprising strong sorption (78%) and weak sorption (19%) on tissue surfaces and absorption within tissues (2%). The adsorption isotherms of PCB 28 indicate that the adsorption capacities of root nodules and shoots were both significantly higher than that of the roots. Both lipids and carbohydrates, and especially lipids, affected the PCB adsorption capacities of the tissues. These results may help in the elucidation of the mechanisms of sorption and accumulation of PCBs in the plants and their main influencing factors and thus contribute to the development of phytoremediation technologies for PCB-contaminated soils.

  7. Disruption of Ethylene Responses by Turnip mosaic virus Mediates Suppression of Plant Defense against the Green Peach Aphid Vector.

    Science.gov (United States)

    Casteel, Clare L; De Alwis, Manori; Bak, Aurélie; Dong, Haili; Whitham, Steven A; Jander, Georg

    2015-09-01

    Plants employ diverse responses mediated by phytohormones to defend themselves against pathogens and herbivores. Adapted pathogens and herbivores often manipulate these responses to their benefit. Previously, we demonstrated that Turnip mosaic virus (TuMV) infection suppresses callose deposition, an important plant defense induced in response to feeding by its aphid vector, the green peach aphid (Myzus persicae), and increases aphid fecundity compared with uninfected control plants. Further, we determined that production of a single TuMV protein, Nuclear Inclusion a-Protease (NIa-Pro) domain, was responsible for changes in host plant physiology and increased green peach aphid reproduction. To characterize the underlying molecular mechanisms of this phenomenon, we examined the role of three phytohormone signaling pathways, jasmonic acid, salicylic acid, and ethylene (ET), in TuMV-infected Arabidopsis (Arabidopsis thaliana), with or without aphid herbivory. Experiments with Arabidopsis mutants ethylene insensitive2 and ethylene response1, and chemical inhibitors of ET synthesis and perception (aminoethoxyvinyl-glycine and 1-methylcyclopropene, respectively), show that the ET signaling pathway is required for TuMV-mediated suppression of Arabidopsis resistance to the green peach aphid. Additionally, transgenic expression of NIa-Pro in Arabidopsis alters ET responses and suppresses aphid-induced callose formation in an ET-dependent manner. Thus, disruption of ET responses in plants is an additional function of NIa-Pro, a highly conserved potyvirus protein. Virus-induced changes in ET responses may mediate vector-plant interactions more broadly and thus represent a conserved mechanism for increasing transmission by insect vectors across generations. © 2015 American Society of Plant Biologists. All Rights Reserved.

  8. Chloroxyanion residue on seeds and sprouts after chlorine dioxide sanitation of alfalfa seed

    Science.gov (United States)

    The effects of a 6-h chlorine dioxide sanitation of alfalfa seed (0, 50, 100, and 200 mg/kg seed) on total coliform bacteria, seed germination, and on the presence of chlorate and perchlorate residues in seed rinse, seed soak, and in alfalfa sprouts was determined. Chlorate residues in 20000 ppm cal...

  9. Gamma-Ray Doses Affected on Alfalfa (Medicago sativa L.)

    International Nuclear Information System (INIS)

    Zayed, E.M; Tarrad, M.M.; Abd El-Daem, G.A.N.A.

    2013-01-01

    Field experiments were conducted at the experimental from, Nuclear Research Center at Inshas. Atomic Energy Authority (AEA) at Egypt during 2011– 2012 growing seasons on alfalfa genotype. The aim of this investigation to evaluate the effect of different gamma ray doses (100-300 Gy) on the alfalfa yield and related traits. Seeds lots of alfalfa genotype were subjected to five gamma ray treatments (100,150,200,250 and 300 Gray). Over all cuts, the dose treatment 300 Gy increased the majority of studied traits i.e., plant height, No. of shoots/plant, fresh weight/plant, fresh yield/Fadden and dry weight yield/fed. The results observed indicated that. In addition, dose of 200 and 250 Gy increased No. of leaves /plant, No. of shoots/plant, stem diameter and fresh weight /plant. However, the plant dry weight was decreased by all doses used and over all cuts, but the dose of 100 and 150 Gy increased leaves /stem ratio. Meanwhile, the later cuts were more affected by irradiation treatments than the earlier ones. In general, the low doses had negative effects on yield traits, but, the relatively high doses exhibited an increase in yield traits

  10. HI-bearing Ultra Diffuse Galaxies in the ALFALFA Survey

    Science.gov (United States)

    Leisman, Lukas; Janowiecki, Steven; Jones, Michael G.; ALFALFA Almost Darks Team

    2018-01-01

    The Arecibo Legacy Fast ALFA (Arecibo L-band Feed Array) extragalactic HI survey, with over 30,000 high significance extragalactic sources, is well positioned to locate gas-bearing, low surface brightness sources missed by optical detection algorithms. We investigate the nature of a population of HI-bearing sources in ALFALFA with properties similar to "ultra-diffuse" galaxies (UDGs): galaxies with stellar masses of dwarf galaxies, but radii of L* galaxies. These "HI-bearing ultra-diffuse" sources (HUDS) constitute a small, but pertinent, fraction of the dwarf-mass galaxies in ALFALFA. They are bluer and have more irregular morphologies than the optically-selected UDGs found in clusters, and they appear to be gas-rich for their stellar mass, indicating low star formation efficiency. To illuminate potential explanations for the extreme properties of these sources we explore their environments and estimate their halo properties. We conclude that environmental mechanism are unlikely the cause of HUDS' properties, as they exist in environments equivalent to that of the other ALFALFA sources of similar HI-masses, however, we do find some suggestion that these HUDS may reside in high spin parameter halos, a potential explanation for their "ultra-diffuse" nature.

  11. Discovery and Targeted LC-MS/MS of Purified Polerovirus Reveals Differences in the Virus-Host Interactome Associated with Altered Aphid Transmission

    Science.gov (United States)

    Howe, Kevin; Fish, Tara; Smith, Dawn; Gildow, Fredrick; MacCoss, Michael J.; Thannhauser, Theodore W.; Gray, Stewart M.

    2012-01-01

    Circulative transmission of viruses in the Luteoviridae, such as cereal yellow dwarf virus (CYDV), requires a series of precisely orchestrated interactions between virus, plant, and aphid proteins. Natural selection has favored these viruses to be retained in the phloem to facilitate acquisition and transmission by aphids. We show that treatment of infected oat tissue homogenate with sodium sulfite reduces transmission of the purified virus by aphids. Transmission electron microscopy data indicated no gross change in virion morphology due to treatments. However, treated virions were not acquired by aphids through the hindgut epithelial cells and were not transmitted when injected directly into the hemocoel. Analysis of virus preparations using nanoflow liquid chromatography coupled to tandem mass spectrometry revealed a number of host plant proteins co-purifying with viruses, some of which were lost following sodium sulfite treatment. Using targeted mass spectrometry, we show data suggesting that several of the virus-associated host plant proteins accumulated to higher levels in aphids that were fed on CYDV-infected plants compared to healthy plants. We propose two hypotheses to explain these observations, and these are not mutually exclusive: (a) that sodium sulfite treatment disrupts critical virion-host protein interactions required for aphid transmission, or (b) that host infection with CYDV modulates phloem protein expression in a way that is favorable for virus uptake by aphids. Importantly, the genes coding for the plant proteins associated with virus may be examined as targets in breeding cereal crops for new modes of virus resistance that disrupt phloem-virus or aphid-virus interactions. PMID:23118947

  12. Discovery and targeted LC-MS/MS of purified polerovirus reveals differences in the virus-host interactome associated with altered aphid transmission.

    Directory of Open Access Journals (Sweden)

    Michelle Cilia

    Full Text Available Circulative transmission of viruses in the Luteoviridae, such as cereal yellow dwarf virus (CYDV, requires a series of precisely orchestrated interactions between virus, plant, and aphid proteins. Natural selection has favored these viruses to be retained in the phloem to facilitate acquisition and transmission by aphids. We show that treatment of infected oat tissue homogenate with sodium sulfite reduces transmission of the purified virus by aphids. Transmission electron microscopy data indicated no gross change in virion morphology due to treatments. However, treated virions were not acquired by aphids through the hindgut epithelial cells and were not transmitted when injected directly into the hemocoel. Analysis of virus preparations using nanoflow liquid chromatography coupled to tandem mass spectrometry revealed a number of host plant proteins co-purifying with viruses, some of which were lost following sodium sulfite treatment. Using targeted mass spectrometry, we show data suggesting that several of the virus-associated host plant proteins accumulated to higher levels in aphids that were fed on CYDV-infected plants compared to healthy plants. We propose two hypotheses to explain these observations, and these are not mutually exclusive: (a that sodium sulfite treatment disrupts critical virion-host protein interactions required for aphid transmission, or (b that host infection with CYDV modulates phloem protein expression in a way that is favorable for virus uptake by aphids. Importantly, the genes coding for the plant proteins associated with virus may be examined as targets in breeding cereal crops for new modes of virus resistance that disrupt phloem-virus or aphid-virus interactions.

  13. Discovery and targeted LC-MS/MS of purified polerovirus reveals differences in the virus-host interactome associated with altered aphid transmission.

    Science.gov (United States)

    Cilia, Michelle; Peter, Kari A; Bereman, Michael S; Howe, Kevin; Fish, Tara; Smith, Dawn; Gildow, Fredrick; MacCoss, Michael J; Thannhauser, Theodore W; Gray, Stewart M

    2012-01-01

    Circulative transmission of viruses in the Luteoviridae, such as cereal yellow dwarf virus (CYDV), requires a series of precisely orchestrated interactions between virus, plant, and aphid proteins. Natural selection has favored these viruses to be retained in the phloem to facilitate acquisition and transmission by aphids. We show that treatment of infected oat tissue homogenate with sodium sulfite reduces transmission of the purified virus by aphids. Transmission electron microscopy data indicated no gross change in virion morphology due to treatments. However, treated virions were not acquired by aphids through the hindgut epithelial cells and were not transmitted when injected directly into the hemocoel. Analysis of virus preparations using nanoflow liquid chromatography coupled to tandem mass spectrometry revealed a number of host plant proteins co-purifying with viruses, some of which were lost following sodium sulfite treatment. Using targeted mass spectrometry, we show data suggesting that several of the virus-associated host plant proteins accumulated to higher levels in aphids that were fed on CYDV-infected plants compared to healthy plants. We propose two hypotheses to explain these observations, and these are not mutually exclusive: (a) that sodium sulfite treatment disrupts critical virion-host protein interactions required for aphid transmission, or (b) that host infection with CYDV modulates phloem protein expression in a way that is favorable for virus uptake by aphids. Importantly, the genes coding for the plant proteins associated with virus may be examined as targets in breeding cereal crops for new modes of virus resistance that disrupt phloem-virus or aphid-virus interactions.

  14. Elevated CO2 concentration around alfalfa nodules increases N2 fixation

    OpenAIRE

    Fischinger, Stephanie A.; Hristozkova, Marieta; Mainassara, Zaman-Allah; Schulze, Joachim

    2009-01-01

    Nodule CO2 fixation via PEPC provides malate for bacteroids and oxaloacetate for N assimilation. The process is therefore of central importance for efficient nitrogen fixation. Nodule CO2 fixation is known to depend on external CO2 concentration. The hypothesis of the present paper was that nitrogen fixation in alfalfa plants is enhanced when the nodules are exposed to elevated CO2 concentrations. Therefore nodulated plants of alfalfa were grown in a hydroponic system that allowed separate ae...

  15. Population Growth Parameters of Rose Aphid, Macrosiphum rosae (Hemiptera: Aphididae) on Different Rose Cultivars.

    Science.gov (United States)

    Golizadeh, A; Jafari-Behi, V; Razmjou, J; Naseri, B; Hassanpour, M

    2017-02-01

    The rose aphid, Macrosiphum rosae (L.), is one of the most important pests on rose plants (Rosa spp.) with a worldwide distribution. As resistance indices, the development, survivorship, and reproduction of this aphid were evaluated on 10 rose cultivars, including Bella Vita, Cool Water, Dolce Vita, Maroussia, Orange Juice, Pinkpromise, Roulette, Tea, Valentine, and Persian Yellow in laboratory at 25 ± 1°C, 65 ± 5% relative humidity, and photoperiod of 16:8 (L/D) h. Rose aphid successfully survived on all 10 rose cultivars, although mortality rate was higher on Tea and Bella Vita. The number of offspring per female differed significantly among the tested rose cultivars, and ranged from 9.2 on Tea to 38.7 nymphs on Orange Juice. Population growth parameters were significantly affected by rose cultivars. The longest mean generation time (T) was observed on Bella Vita (14.8 days) and Tea (14.7 days) and the shortest on Orange Juice (10.0 days). The net reproductive rate (R 0 ) ranged from 6.9 on Tea to 33.2 nymphs on Orange Juice cultivar. Correspondingly, the highest value of intrinsic rate of increase (r m ) was observed on Orange Juice (0.348 day -1 ) and lower values on Tea (0.131 day -1 ) followed by Bella Vita (0.154 day -1 ). Cluster analysis of all the measured parameters of rose aphid on different rose cultivars revealed that Tea and Bella Vita were relatively resistant to M. rosae. These findings could be useful in developing an integrated pest management (IPM) program for this aphid in urbanized areas and commercial rose potting.

  16. Resistance to lettuce aphid (Nasonovia ribisnigri) biotype 0 in wild lettuce accessions PI 491093 and PI 274378

    Science.gov (United States)

    Lettuce aphid, Nasonovia ribisnigri Mosley (Homoptera : Aphididae), is a major insect pest of lettuce, Lactuca sativa L, in many commercial lettuce productions areas around the world. Resistance to lettuce aphid was first reported in Lactuca virosa L. accession IVT 280 and characterized as complete,...

  17. Genetics coupled to quantitative intact proteomics links heritable aphid and endosymbiont protein isoform expression to polerovirus transmission

    Science.gov (United States)

    Yellow dwarf viruses in the family Luteoviridae, such as Cereal yellow dwarf virus-RPV (CYDV-RPV), are vectored by aphids and cause the most economically important virus disease of cereal crops worldwide. The identification of aphid proteins mediating virus transmission will better define transmiss...

  18. Resistance to a new biotype of the lettuce aphid Nasonovia ribisnigri in Lactuca virosa accession IVT280

    NARCIS (Netherlands)

    Broeke, ten C.J.M.; Dicke, M.; Loon, van J.J.A.

    2013-01-01

    Host plant resistance is an effective protection strategy to control aphids in many crops. However, the evolution of insensitive aphid biotypes necessitates the search for new resistance sources. Wild relatives of crop plants can be important sources for resistance genes to be introgressed into new

  19. Effectiveness of neutral detergent fiber in whole cottonseed and dried distillers grains compared with alfalfa haylage.

    Science.gov (United States)

    Clark, P W; Armentano, L E

    1993-09-01

    Sixteen Holstein cows in midlactation were used in a 4 x 4 Latin square design to determine the effect of replacing alfalfa NDF with NDF from whole, linted cottonseed or dried distillers grains. Low and high fiber control diets (13 and 19% of dietary DM from alfalfa haylage NDF, respectively) were compared with diets designed to contain 13% of DM from alfalfa haylage NDF plus 6% of DM from either cottonseed NDF or distillers grains NDF. Dry matter intake, milk yield, and milk protein yield were lower from the high fiber control diet. Milk fat percentage was lower for the low fiber control diet. The cottonseed diet was equal to the high fiber control diet in stimulating rumination. Rumen acetate to propionate ratio was higher for the high fiber control and cottonseed diets. Replacing alfalfa with either of these high fiber by-product feeds increased feed intake and yields of milk fat and protein. The effectiveness of the NDF in distillers grains and cottonseed was not significantly different from that of alfalfa NDF for maintaining milk fat yield. Whole cottonseed and dried distillers grains appear to be good sources of effective fiber for maintaining milk fat test when they are substituted for alfalfa haylage fiber in lactating cow rations.

  20. Predator efficiency reconsidered for a ladybird-aphid system

    Czech Academy of Sciences Publication Activity Database

    Kindlmann, Pavel; Yasuda, H.; Kajita, Y.; Sato, S.; Dixon, Anthony F. G.

    2015-01-01

    Roč. 3, mar (2015), s. 27 ISSN 2296-701X R&D Projects: GA MŠk(CZ) LO1415; GA ČR GB14-36098G Institutional support: RVO:67179843 Keywords : biological control * generation time ratio * population dynamics * predator-prey systems * ladybirds * aphids Subject RIV: EH - Ecology, Behaviour

  1. Wheat Nitrogen Fertilisation Effects on the Performance of the Cereal Aphid Metopolophium dirhodum

    Directory of Open Access Journals (Sweden)

    Alan F. J. Gash

    2012-02-01

    Full Text Available The effects of five rates of nitrogen fertiliser applications on the performance of the cereal aphid Metopolophium dirhodum on winter wheat, within the range of rates recommended for UK crops, were investigated over two seasons in field-grown crops and also on plants grown in the glasshouse. Longevity was unaffected by the level of fertilisation, but aphid intrinsic rate of increase and fecundity increased with each level applied. In the second field season, when a higher upper limit was used, many of these increases were significant. A previously unreported finding for this species was that there was a significant decrease in fecundity for the highest rate of fertilisation. Results for the glasshouse-reared aphids followed a similar pattern to those in the field, and overall they underline recent reports in the literature of the negative effects of high nutrient concentrations on the performance of herbivorous insects. The underlying reasons for these are discussed.

  2. The entomopathogenic fungal endophytes Purpureocillium lilacinum (formerly Paecilomyces lilacinus) and Beauveria bassiana negatively affect cotton aphid reproduction under both greenhouse and field conditions.

    Science.gov (United States)

    Castillo Lopez, Diana; Zhu-Salzman, Keyan; Ek-Ramos, Maria Julissa; Sword, Gregory A

    2014-01-01

    The effects of two entomopathogenic fungal endophytes, Beauveria bassiana and Purpureocillium lilacinum (formerly Paecilomyces lilacinus), were assessed on the reproduction of cotton aphid, Aphis gossypii Glover (Homoptera:Aphididae), through in planta feeding trials. In replicate greenhouse and field trials, cotton plants (Gossypium hirsutum) were inoculated as seed treatments with two concentrations of B. bassiana or P. lilacinum conidia. Positive colonization of cotton by the endophytes was confirmed through potato dextrose agar (PDA) media plating and PCR analysis. Inoculation and colonization of cotton by either B. bassiana or P. lilacinum negatively affected aphid reproduction over periods of seven and 14 days in a series of greenhouse trials. Field trials were conducted in the summers of 2012 and 2013 in which cotton plants inoculated as seed treatments with B. bassiana and P. lilacinum were exposed to cotton aphids for 14 days. There was a significant overall effect of endophyte treatment on the number of cotton aphids per plant. Plants inoculated with B. bassiana had significantly lower numbers of aphids across both years. The number of aphids on plants inoculated with P. lilacinum exhibited a similar, but non-significant, reduction in numbers relative to control plants. We also tested the pathogenicity of both P. lilacinum and B. bassiana strains used in the experiments against cotton aphids in a survival experiment where 60% and 57% of treated aphids, respectively, died from infection over seven days versus 10% mortality among control insects. Our results demonstrate (i) the successful establishment of P. lilacinum and B. bassiana as endophytes in cotton via seed inoculation, (ii) subsequent negative effects of the presence of both target endophytes on cotton aphid reproduction using whole plant assays, and (iii) that the P. lilacinum strain used is both endophytic and pathogenic to cotton aphids. Our results illustrate the potential of using these

  3. The entomopathogenic fungal endophytes Purpureocillium lilacinum (formerly Paecilomyces lilacinus and Beauveria bassiana negatively affect cotton aphid reproduction under both greenhouse and field conditions.

    Directory of Open Access Journals (Sweden)

    Diana Castillo Lopez

    Full Text Available The effects of two entomopathogenic fungal endophytes, Beauveria bassiana and Purpureocillium lilacinum (formerly Paecilomyces lilacinus, were assessed on the reproduction of cotton aphid, Aphis gossypii Glover (Homoptera:Aphididae, through in planta feeding trials. In replicate greenhouse and field trials, cotton plants (Gossypium hirsutum were inoculated as seed treatments with two concentrations of B. bassiana or P. lilacinum conidia. Positive colonization of cotton by the endophytes was confirmed through potato dextrose agar (PDA media plating and PCR analysis. Inoculation and colonization of cotton by either B. bassiana or P. lilacinum negatively affected aphid reproduction over periods of seven and 14 days in a series of greenhouse trials. Field trials were conducted in the summers of 2012 and 2013 in which cotton plants inoculated as seed treatments with B. bassiana and P. lilacinum were exposed to cotton aphids for 14 days. There was a significant overall effect of endophyte treatment on the number of cotton aphids per plant. Plants inoculated with B. bassiana had significantly lower numbers of aphids across both years. The number of aphids on plants inoculated with P. lilacinum exhibited a similar, but non-significant, reduction in numbers relative to control plants. We also tested the pathogenicity of both P. lilacinum and B. bassiana strains used in the experiments against cotton aphids in a survival experiment where 60% and 57% of treated aphids, respectively, died from infection over seven days versus 10% mortality among control insects. Our results demonstrate (i the successful establishment of P. lilacinum and B. bassiana as endophytes in cotton via seed inoculation, (ii subsequent negative effects of the presence of both target endophytes on cotton aphid reproduction using whole plant assays, and (iii that the P. lilacinum strain used is both endophytic and pathogenic to cotton aphids. Our results illustrate the potential of

  4. Inter- and intra-guild interactions related to aphids in nettle (Urtica dioica L.) strips closed to field crops.

    Science.gov (United States)

    Alhmedi, A; Haubruge, E; Bodson, B; Francis, F

    2006-01-01

    A field experiment designed to assess the biodiversity related to nettle strips closed to crops, and more particularly the aphid and related beneficial populations, was established in experimental farm located in Gembloux (Belgium). Margin strips of nettle (Urtica dioica) closed to wheat (Triticum aestivum), green pea (Pisum sativum) and rape (Brassicae napus) fields were investigated. The diversity, abundance of aphids and related predators were analysed according to the plant crop species and the differential pesticide application (treated plot and control). Insects were visually observed every week during all the cultivation season. Two main families of aphidophagous predators were found in all field crops and nettle, the Coccinellidae and Syrphidae. The diversity of the aphidophagous predators was shown to be higher on nettle than in field crops, particularly the Chrysopidae, the Anthocoridae and the Miridae. However, a striking difference of ladybird abundance was observed according to the aphid host plant. In one side, Coccinella septempunctata was much more abundant on Acyrthosiphon pisum infested green pea than on the other host plant species. At the opposite, higher occurrence of Harmonia axyridis was observed on the aphid infested nettle plants than on the crop plants. In particular, none of H. axyridis was found in wheat crop. Also, more than only a significant positive correlation between predator and aphid abundance, specialised relations between particular aphid species and some so-called generalist predators was determined in the fields. Finally, intraguild interactions between the aphidophagous predators was assessed and shown that only a significant negative correlation between Episyrphus balteatus and H. axyridis related to the nettle aphid, Micrlophium carnosum, was observed. The relative distribution of the ladybirds, namely C. septempunctata and H. axyridis according to the host plant, nettle strips and crop plots was discussed in relation to

  5. The effect of within-crop habitat manipulations on the conservation biological control of aphids in field-grown lettuce.

    Science.gov (United States)

    Skirvin, D J; Kravar-Garde, L; Reynolds, K; Wright, C; Mead, A

    2011-12-01

    Within-crop habitat manipulations have the potential to increase the biological control of pests in horticultural field crops. Wildflower strips have been shown to increase the abundance of natural enemies, but there is little evidence to date of an impact on pest populations. The aim of this study was to determine whether within-crop wildflower strips can increase the natural regulation of pests in horticultural field crops. Aphid numbers in plots of lettuce grown adjacent to wildflower strips were compared with those in plots grown in the absence of wildflowers. The presence of wildflower strips led to a decrease in aphid numbers on adjacent lettuce plants during June and July, but had less impact in August and September. The decrease in aphid numbers was greatest close to the wildflower strips and, the decrease in aphid numbers declined with increasing distance from the wildflower strips, with little effect at a distance of ten metres. The main natural enemies found in the crop were those that dispersed aerially, which is consistent with data from previous studies on cereal crops. Analysis and interpretation of natural enemy numbers was difficult due to low recovery of natural enemies, and the numbers appeared to follow changes in aphid abundance rather than being directly linked to the presence of wildflower strips. Cutting the wildflower strips, to remove floral resources, had no impact on the reduction in aphid numbers achieved during June and July, but decreased the effect of the wildflower strips during August and September. The results suggest that wildflower strips can lead to increased natural regulation of pest aphids in outdoor lettuce crops, but more research is required to determine how this is mediated by natural enemies and how the impact of wildflower strips on natural pest regulation changes during the growing season.

  6. Water sensors with cellular system eliminate tail water drainage in alfalfa irrigation

    Directory of Open Access Journals (Sweden)

    Rajat Saha

    2011-10-01

    Full Text Available Alfalfa is the largest consumer of water among all crops in California. It is generally flood-irrigated, so any system that decreases runoff can improve irrigation efficiency and conserve water. To more accurately manage the water flow at the tail (bottom end of the field in surface-irrigated alfalfa crops, we developed a system that consists of wetting-front sensors, a cellular communication system and a water advance model. This system detects the wetting front, determines its advance rate and generates a cell-phone alert to the irrigator when the water supply needs to be cut off, so that tail water drainage is minimized. To test its feasibility, we conducted field tests during the 2008 and 2009 alfalfa growing seasons. The field experiments successfully validated the methodology, producing zero tail water drainage.

  7. Identification of an intraspecific alarm pheromone and two conserved odorant-binding proteins associated with (E)-β-farnesene perception in aphid Rhopalosiphum padi.

    Science.gov (United States)

    Fan, Jia; Xue, Wenxin; Duan, Hongxia; Jiang, Xin; Zhang, Yong; Yu, Wenjuan; Jiang, Shanshan; Sun, Jingrun; Chen, Julian

    2017-08-01

    (E)-β-farnesene (EBF) is the common active component of aphid alarm pheromone. Either or both of two orthologs of ordorant-binding proteins (OBPs), OBP3 and OBP7, recently reported in aphids, may be involved in EBF perception. The aim of this study was to investigate the respondence of the aphid Rhopalosiphum padi to its intraspecific alarm pheromone and which OBP is responsible for that response. We tested the olfactory response of the aphid R. padi to EBF and freshly crushed aphids. Then, we extracted the volatiles from crushed aphids using solid phase microextraction (SPME) for analysis with GC×GC-TOF/MS. We also cloned two OBPs cDNAs in R. padi (RpadOBP3 and RpadOBP7) and expressed them in competent Escherichia coli cells. Both recombinant proteins, RpadOBP3 and RpadOBP7, bound EBF well, with RpadOBP7 having specifically stronger affinity for EBF than for other volatiles. Based on the crystal structure of the OBPs with high identity, we performed homology modeling and analyzed the interactions between RpadOBPs and EBF. In conclusion, R. padi was repelled by both EBF and crushed aphids. EBF was identified as the only volatile that acted as the alarm pheromone. Our results indicated that OBP7 is a potential molecular target to control wheat aphids by disturbing their behaviors to the alarm pheromone. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Role of Pea Enation Mosaic Virus Coat Protein in the Host Plant and Aphid Vector

    Directory of Open Access Journals (Sweden)

    Juliette Doumayrou

    2016-11-01

    Full Text Available Understanding the molecular mechanisms involved in plant virus–vector interactions is essential for the development of effective control measures for aphid-vectored epidemic plant diseases. The coat proteins (CP are the main component of the viral capsids, and they are implicated in practically every stage of the viral infection cycle. Pea enation mosaic virus 1 (PEMV1, Enamovirus, Luteoviridae and Pea enation mosaic virus 2 (PEMV2, Umbravirus, Tombusviridae are two RNA viruses in an obligate symbiosis causing the pea enation mosaic disease. Sixteen mutant viruses were generated with mutations in different domains of the CP to evaluate the role of specific amino acids in viral replication, virion assembly, long-distance movement in Pisum sativum, and aphid transmission. Twelve mutant viruses were unable to assemble but were able to replicate in inoculated leaves, move long-distance, and express the CP in newly infected leaves. Four mutant viruses produced virions, but three were not transmissible by the pea aphid, Acyrthosiphon pisum. Three-dimensional modeling of the PEMV CP, combined with biological assays for virion assembly and aphid transmission, allowed for a model of the assembly of PEMV coat protein subunits.

  9. Role of Pea Enation Mosaic Virus Coat Protein in the Host Plant and Aphid Vector.

    Science.gov (United States)

    Doumayrou, Juliette; Sheber, Melissa; Bonning, Bryony C; Miller, W Allen

    2016-11-18

    Understanding the molecular mechanisms involved in plant virus-vector interactions is essential for the development of effective control measures for aphid-vectored epidemic plant diseases. The coat proteins (CP) are the main component of the viral capsids, and they are implicated in practically every stage of the viral infection cycle. Pea enation mosaic virus 1 (PEMV1, Enamovirus , Luteoviridae ) and Pea enation mosaic virus 2 (PEMV2, Umbravirus , Tombusviridae ) are two RNA viruses in an obligate symbiosis causing the pea enation mosaic disease. Sixteen mutant viruses were generated with mutations in different domains of the CP to evaluate the role of specific amino acids in viral replication, virion assembly, long-distance movement in Pisum sativum , and aphid transmission. Twelve mutant viruses were unable to assemble but were able to replicate in inoculated leaves, move long-distance, and express the CP in newly infected leaves. Four mutant viruses produced virions, but three were not transmissible by the pea aphid, Acyrthosiphon pisum . Three-dimensional modeling of the PEMV CP, combined with biological assays for virion assembly and aphid transmission, allowed for a model of the assembly of PEMV coat protein subunits.

  10. Winter treatments against the woolly apple aphid (Eriosoma lanigerum): products and timing of applications

    OpenAIRE

    Kelderer, Markus; Lardschneider, Ewald; Casera, Claudio

    2008-01-01

    In organic apple growing the woolly apple aphid (Eriosoma lanigerum) is still an unsolved problem. Various approaches to use beneficial insects were not really effective. Only winter treatments with mineral oils showed partial and fluctuating success. In 2006 and 2007 field trials were carried out to evaluate the efficacy of winter treatments to control woolly apple aphids. The efficacy of several products (different mineral oils, lime sulphur, and lime sulphur + mineral oil) w...

  11. Uptake and translocation of sulfamethazine by alfalfa grown under hydroponic conditions.

    Science.gov (United States)

    Kurwadkar, Sudarshan; Struckhoff, Garrett; Pugh, Kameron; Singh, Om

    2017-03-01

    Antibiotics are routinely used in intensive animal agriculture operations collectively known as Concentrated Animal Feed Operations (CAFO) which include dairy, poultry and swine farms. Wastewater generated by CAFOs often contains low levels of antibiotics and is typically managed in an anaerobic lagoon. The objective of this research is to investigate the uptake and fate of aqueous sulfamethazine (SMN) antibiotic by alfalfa (Medicago sativa) grass grown under hydroponic conditions. Uptake studies were conducted using hydroponically grown alfalfa in a commercially available nutrient solution supplemented with 10mg/L of SMN antibiotic. Analysis of alfalfa sap, root zone, middle one-third, and top portion of the foliage showed varying uptake rate and translocation of SMN. The highest average amount of SMN (8.58μg/kg) was detected in the root zone, followed by the top portion (1.89μg/kg), middle one-third (1.30μg/kg), and sap (0.38μg/kg) samples, indicating a clear distribution of SMN within the sampled regions. The ultraviolet (UV) spectra of parent SMN and translocated SMN identified in different parts of the plant present the possibility of metabolization during the uptake process. Uptake of SMN using alfalfa grown under hydroponic conditions has potential as a promising remediation technology for removal of similar antibiotics from wastewater lagoons. Copyright © 2016. Published by Elsevier B.V.

  12. Alternaria toxin-induced resistance in rose plants against rose aphid (Macrosiphum rosivorum): effect of tenuazonic acid.

    Science.gov (United States)

    Yang, Fa-zhong; Yang, Bin; Li, Bei-bei; Xiao, Chun

    2015-04-01

    Many different types of toxins are produced by the fungus, Alternaria alternata (Fr.) Keissler. Little is known, however, regarding the influence of these toxins on insects. In this study, we investigated the toxin-induced inhibitory effects of the toxin produced by A. alternata on the rose aphid, Macrosiphum rosivorum, when the toxin was applied to leaves of the rose, Rosa chinensis. The results demonstrated that the purified crude toxin was non-harmful to rose plants and rose aphids, but had an intensive inhibitory effect on the multiplication of aphids. The inhibitory index against rose aphids reached 87.99% when rose plants were sprayed with the toxin solution at a low concentration. Further results from bioassays with aphids and high performance liquid chromatography (HPLC) analyses demonstrated that tenuazonic acid (TeA) was one of the most important resistance-related active components in the crude toxin. The content of TeA was 0.1199% in the crude toxin under the HPLC method. Similar to the crude toxin, the inhibitory index of pure TeA reached 83.60% 15 d after the rose plants were sprayed with pure TeA solution at the lower concentration of 0.060 μg/ml, while the contents of residual TeA on the surface and in the inner portion of the rose plants were only 0.04 and 0.00 ng/g fresh weight of TeA-treated rose twigs, respectively, 7 d after the treatment. Our results show that TeA, an active component in the A. alternata toxin, can induce the indirect plant-mediated responses in rose plants to intensively enhance the plant's resistances against rose aphids, and the results are very helpful to understand the plant-mediated interaction between fungi and insects on their shared host plants.

  13. Variation in alfalfa leafcutting bee, Megachile rotundata, reproductive success according to location of nests in U.S. commercial domiciles

    Science.gov (United States)

    The alfalfa leafcutting bee, Megachile rotundata F., is used extensively to pollinate alfalfa for seed production in western North America. However, it usually is not possible to sustain bee populations in the United States. Variable microenvironments are experienced by developing alfalfa leafcutt...

  14. Systemic Propagation of a Fluorescent Infectious Clone of a Polerovirus Following Inoculation by Agrobacteria and Aphids.

    Science.gov (United States)

    Boissinot, Sylvaine; Pichon, Elodie; Sorin, Céline; Piccini, Céline; Scheidecker, Danièle; Ziegler-Graff, Véronique; Brault, Véronique

    2017-06-29

    A fluorescent viral clone of the polerovirus Turnip yellows virus (TuYV) was engineered by introducing the Enhanced Green Fluorescent Protein (EGFP) sequence into the non-structural domain sequence of the readthrough protein, a minor capsid protein. The resulting recombinant virus, referred to as TuYV-RT GFP , was infectious in several plant species when delivered by agroinoculation and invaded efficiently non-inoculated leaves. As expected for poleroviruses, which infect only phloem cells, the fluorescence emitted by TuYV-RT GFP was restricted to the vasculature of infected plants. In addition, TuYV-RT GFP was aphid transmissible and enabled the observation of the initial sites of infection in the phloem after aphid probing in epidermal cells. The aphid-transmitted virus moved efficiently to leaves distant from the inoculation sites and importantly retained the EGFP sequence in the viral genome. This work reports on the first engineered member in the Luteoviridae family that can be visualized by fluorescence emission in systemic leaves of different plant species after agroinoculation or aphid transmission.

  15. Aboveground feeding by soybean aphid, Aphis glycines, affects soybean cyst nematode, Heterodera glycines, reproduction belowground.

    Directory of Open Access Journals (Sweden)

    Michael T McCarville

    Full Text Available Heterodera glycines is a cyst nematode that causes significant lost soybean yield in the U.S. Recent studies observed the aphid Aphis glycines and H. glycines interacting via their shared host, soybean, Glycine max. A greenhouse experiment was conducted to discern the effect of A. glycines feeding on H. glycines reproduction. An H. glycines-susceptible cultivar, Kenwood 94, and a resistant cultivar, Dekalb 27-52, were grown in H. glycines-infested soil for 30 and 60 d. Ten days after planting, plants were infested with either zero, five, or ten aphids. At 30 and 60 d, the number of H. glycines females and cysts (dead females and the number of eggs within were counted. In general, H. glycines were less abundant on the resistant than the susceptible cultivar, and H. glycines abundance increased from 30 to 60 d. At 30 d, 33% more H. glycines females and eggs were produced on the resistant cultivar in the ten-aphid treatment compared to the zero-aphid treatment. However, at 30 d the susceptible cultivar had 50% fewer H. glycines females and eggs when infested with ten aphids. At 60 d, numbers of H. glycines females and cysts and numbers of eggs on the resistant cultivar were unaffected by A. glycines feeding, while numbers of both were decreased by A. glycines on the susceptible cultivar. These results indicate that A. glycines feeding improves the quality of soybean as a host for H. glycines, but at higher herbivore population densities, this effect is offset by a decrease in resource quantity.

  16. Effectivenes of inoculation in alfalfa breeding in ecological conditions of the Bjelovar and Bilogora county

    Directory of Open Access Journals (Sweden)

    Darko Uher

    2012-09-01

    Full Text Available Development and basic existence of animal production as well as production of high quality milk depends upon possibility of sufficient production of quality and protein sufficient forage. Forage crop that satisfies these demands is alfalfa which is one of the most important perennial forage crop legumes. The aim of this study was to enhance alfalfa production on acid soil by liming and alfalfa seed inoculation with efficient Sinorhizobium meliloti strains in order to reduce the use of mineral nitrogen fertilization and enable qualitative and cost effective production of forage on the dairy farms. Field trial was established at family farm in the area of Bjelovar and Bilogora county. During two years experimental period statistically significant influence of inoculation and liming on forage and dry matteryield was determined. Significantly the lowest yields were determined on untreated plots without liming material. In all untreated plots, significantly lower yields were determined, but significant differences in yields were also obtained by inoculation with different S. meliloti strains, emphasizing the importance of strains selection used for alfalfa inoculation. In both experimental years total forage yield were ranging from 34 t/ha (untreated plots without liming up to 60 t/ha on plots inoculated with strain 2011 and without liming. Values of total dry matter yield for both experimental years ranged from 6.5 t/ha (untreated plots without liming up to 15,7 t/ha on plots inoculated with strain 2011 without liming. Results of this study showed that application of liming materials for acidity removal had positive effect on alfalfa yields in both experimental years and significantly improved alfalfa production on acid soils. The results of this study clearly showed that inoculation with selected S. meliloti strains may improve alfalfa production on acid soils and may contribute to more efficient forage production for dairy farms under particular

  17. Transcriptome analysis of resistant and susceptible alfalfa cultivars infected with root-knot nematode Meloidogyne incognita.

    Directory of Open Access Journals (Sweden)

    Olga A Postnikova

    Full Text Available Nematodes are one of the major limiting factors in alfalfa production. Root-knot nematodes (RKN, Meloidogyne spp. are widely distributed and economically important sedentary endoparasites of agricultural crops and they may inflict significant damage to alfalfa fields. As of today, no studies have been published on global gene expression profiling in alfalfa infected with RKN or any other plant parasitic nematode. Very little information is available about molecular mechanisms that contribute to pathogenesis and defense responses in alfalfa against these pests and specifically against RKN. In this work, we performed root transcriptome analysis of resistant (cv. Moapa 69 and susceptible (cv. Lahontan alfalfa cultivars infected with RKN Meloidogyne incognita, widespread root-knot nematode species and a major pest worldwide. A total of 1,701,622,580 pair-end reads were generated on an Illumina Hi-Seq 2000 platform from the roots of both cultivars and assembled into 45,595 and 47,590 transcripts in cvs Moapa 69 and Lahontan, respectively. Bioinformatic analysis revealed a number of common and unique genes that were differentially expressed in susceptible and resistant lines as a result of nematode infection. Although the susceptible cultivar showed a more pronounced defense response to the infection, feeding sites were successfully established in its roots. Characteristically, basal gene expression levels under normal conditions differed between the two cultivars as well, which may confer advantage to one of the genotypes toward resistance to nematodes. Differentially expressed genes were subsequently assigned to known Gene Ontology categories to predict their functional roles and associated biological processes. Real-time PCR validated expression changes in genes arbitrarily selected for experimental confirmation. Candidate genes that contribute to protection against M. incognita in alfalfa were proposed and alfalfa-nematode interactions with

  18. Cellular tropism, population dynamics, host range and taxonomic status of an aphid secondary symbiont, SMLS (Sitobion miscanthi L type symbiont.

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    Tong Li

    Full Text Available SMLS (Sitobion miscanthi L type symbiont is a newly reported aphid secondary symbiont. Phylogenetic evidence from molecular markers indicates that SMLS belongs to the Rickettsiaceae and has a sibling relationship with Orientia tsutsugamushi. A comparative analysis of coxA nucleotide sequences further supports recognition of SMLS as a new genus in the Rickettsiaceae. In situ hybridization reveals that SMLS is housed in both sheath cells and secondary bacteriocytes and it is also detected in aphid hemolymph. The population dynamics of SMLS differ from those of Buchnera aphidicola and titer levels of SMLS increase in older aphids. A survey of 13 other aphids reveals that SMLS only occurs in wheat-associated species.

  19. Effects of alfalfa germplasm and stage of maturity on digestive process and productive response of dairy cows fed alfalfa hay-based diets

    Directory of Open Access Journals (Sweden)

    Igino Andrighetto

    2010-01-01

    Full Text Available The effects on the digestive process and the productive performances of dairy cows fed diets containing alfalfa hay from  different germplasms and maturity were assessed in the present study. Three different lots of first-cut alfalfa hay were  used in the study: the improved variety “Boreal”, harvested at two consecutive maturity stages (early flowering and full  flowering and the ecotype “Vogherese”, at full flowering. Cutting the plant at an earlier stage of maturity improved hay  quality in comparison with the more mature forages (crude protein: 21.4 vs 16.5% DM; P  DM; P  er lignin content for the latter (8.6 vs 8.2% DM; P  tating cows were formulated using an equal amount of corn silage and the maximum inclusion of one of the tested hays  as forage base. The better quality of the early cut hay made it possible to increase its inclusion in the diet up to 44% of  total dietary DM, while the two more mature hays covered only 36% of total DM of the respective diets. According to a  3 x 3 Latin square design, the diets were fed to 3 Italian Brown cows (initial average days in milk 121 ± 24 and milk  yield 20 kg ± 1.3 fitted with ruminal cannula in 3 consecutive periods of 28 d each. Alfalfa stage of maturity and  germplasm did not affect dietary DM intake (average 16 kg/d. Degradability parameters of dietary DM, calculated by in  situ nylon bags technique, showed similar kinetics of rumen disappearance for all diets. No differences were noticed in  the ruminal rate of passage of the solid phase among diets, while the liquid phase showed a slower rate of passage for  the early flowering hay diet. Consistent with the degradation process, the stage of maturity or the alfalfa germplasm did  not affect the rumen fluid data or the in vivo digestibility coefficients of the diets. Milk yield did not show any change due  to either alfalfa maturity or cultivar, while milk protein was lowered when cows received the early cut hay

  20. Performance and feeding behaviour of two biotypes of the black currant-lettuce aphid, Nasonovia ribisnigri, on resistant and susceptible Lactuca sativa near-isogenic lines.

    Science.gov (United States)

    ten Broeke, Cindy J M; Dicke, Marcel; van Loon, Joop J A

    2013-10-01

    The black currant-lettuce aphid, Nasonovia ribisnigri, is an important pest of cultivated lettuce, Lactuca sativa. Since 1982, the control of this aphid on lettuce is largely based on host plant resistance, conferred by the Nr gene, introgressed from Lactuca virosa. The resistance mechanism remains to be identified. N. ribisnigri populations virulent on the Nr-based resistance in lettuce have emerged in several locations in Europe since 2007. The objective of this study was to investigate the resistance mechanism mediated by the Nr gene in lettuce by detailed studies of aphid feeding behaviour and performance. Both avirulent (Nr:0) and virulent (Nr:1)biotypes of N. ribisnigri were studied on five resistant and two susceptible near isogenic lines (NILs). In addition, survival and colony development were quantified.Nr:0 aphids showed a strong decrease in sieve element ingestion and took longer to accept a sieve element on resistant NILs compared with susceptible NILs, and no aphids survived on the resistant NIL. Nr:1 aphids fed and performed equally well on the resistant and susceptible NILs. The resistance mechanism against Nr:0 aphids encoded by the Nr gene seems to be located in the phloem, although we also observed differences in feeding behaviour during the pathway phase to the phloem. Nr:1 aphids were highly virulent to the resistance conferred by the Nr gene. The consequences of the appearance of Nr:1 aphids for control of N. ribisnigri are discussed.

  1. Virus-induced gene silencing of WRKY53 and an inducible phenylalanine ammonia-lyase in wheat reduces aphid resistance

    Science.gov (United States)

    Although several wheat genes differentially expressed during the Russian wheat aphid resistance response have recently been identified, their requirement for and specific role in resistance remain unclear. Progress in wheat-aphid interaction research is hampered by inadequate collections of mutant g...

  2. Russian wheat aphid, Diuraphis noxia in the Czech Republic – cause of the significant population decrease

    Czech Academy of Sciences Publication Activity Database

    Havelka, Jan; Žurovcová, Martina; Rychlý, S.; Starý, Petr

    2014-01-01

    Roč. 138, č. 4 (2014), s. 273-280 ISSN 0931-2048 R&D Projects: GA ČR GA522/09/1940 Institutional support: RVO:60077344 Keywords : alien aphid species * anholocyclic populations * aphids overwintering mortality Subject RIV: EH - Ecology, Behaviour Impact factor: 1.650, year: 2014 http://onlinelibrary.wiley.com/doi/10.1111/jen.12068/pdf

  3. Multi-modal defences in aphids offer redundant protection and increased costs likely impeding a protective mutualism.

    Science.gov (United States)

    Martinez, Adam J; Doremus, Matthew R; Kraft, Laura J; Kim, Kyungsun L; Oliver, Kerry M

    2018-03-01

    The pea aphid, Acyrthosiphon pisum, maintains extreme variation in resistance to its most common parasitoid wasp enemy, Aphidius ervi, which is sourced from two known mechanisms: protective bacterial symbionts, most commonly Hamiltonella defensa, or endogenously encoded defences. We have recently found that individual aphids may employ each defence individually, occasionally both defences together, or neither. In field populations, Hamiltonella-infected aphids are found at low to moderate frequencies and while less is known about the frequency of resistant genotypes, they show up less often than susceptible genotypes in field collections. To better understand these patterns, we sought to compare the strengths and costs of both types of defence, individually and together, in order to elucidate the selective pressures that maintain multi-modal defence mechanisms or that may favour one over the other. We experimentally infected five aphid genotypes (two lowly and three highly resistant), each with two symbiont strains, Hamiltonella-APSE8 (moderate protection) and Hamiltonella-APSE3 (high protection). This resulted in three sublines per genotype: uninfected, +APSE8 and +APSE3. Each of the 15 total sublines was first subjected to a parasitism assay to determine its resistance phenotype and in a second experiment, a subset was chosen to compare fitness (fecundity and survivorship) in the presence and absence of parasitism. In susceptible aphid genotypes, parasitized sublines infected with Hamiltonella generally showed increased protection with direct fitness benefits, but clear infection costs to fitness in the absence of parasitism. In resistant genotypes, Hamiltonella infection rarely conferred additional protection, often further reduced fecundity and survivorship when enemy challenged, and resulted in constitutive fitness costs in the absence of parasitism. We also identified strong aphid genotype × symbiont-strain interactions, such that the best defensive

  4. Silicon Priming Created an Enhanced Tolerance in Alfalfa (Medicago sativa L.) Seedlings in Response to High Alkaline Stress.

    Science.gov (United States)

    Liu, Duo; Liu, Miao; Liu, Xiao-Long; Cheng, Xian-Guo; Liang, Zheng-Wei

    2018-01-01

    Alkaline stress as a result of higher pH usually triggers more severe physiological damage to plants than that of saline stress with a neutral pH. In the present study, we demonstrated that silicon (Si) priming of alfalfa ( Medicago sativa L.) seedlings increased their tolerance to high alkaline stress situations. Gongnong No. 1 seedlings were subjected to alkaline stress simulated by 25 mM Na 2 CO 3 (pH 11.2). Alkaline stress greatly decreased the biomass and caused severe lodging or wilting of alfalfa seedlings. In contrast, the application of Si to alfalfa seedlings 36 h prior to the alkaline treatment significantly alleviated the damage symptoms and greatly increased the biomass and chlorophyll content. Because of being concomitant with increasing photosynthesis and water use efficiency, decreasing membrane injury and malondialdehyde content, and increasing peroxidase and catalase ascorbate activities in alfalfa leaves, thereby alleviating the triggered oxidative damage by alkaline stress to the plant. Furthermore, Si priming significantly decreased the accumulation of protein and proline content in alfalfa, thus reducing photosynthetic feedback repression. Si priming significantly accumulated more Na in the roots, but led to a decrease of Na accumulation and an increase of K accumulation in the leaves under alkaline stress. Meanwhile, Si priming decreased the accumulation of metal ions such as Mg, Fe, Mn, and Zn in the roots of alfalfa seedlings under alkaline stress. Collectively, these results suggested that Si is involved in the metabolic or physiological changes and has a potent priming effect on the alkaline tolerance of alfalfa seedlings. The present study indicated that Si priming is a new approach to improve the alkaline tolerance in alfalfa and provides increasing information for further exploration of the alkaline stress response at the molecular level in alfalfa.

  5. Responses to ozone pollution of alfalfa exposed to increasing salinity levels

    International Nuclear Information System (INIS)

    Maggio, Albino; Chiaranda, Fabrizio Quaglietta; Cefariello, Roberto; Fagnano, Massimo

    2009-01-01

    Stomatal closure and biosynthesis of antioxidant molecules are two fundamental components of the physiological machinery that lead to stress adaptation during plant's exposure to salinity. Since high stomatal resistance may also contribute in counteracting O 3 damages, we hypothesized that soil salinization may increase O 3 tolerance of crops. An experiment was performed with alfalfa grown in filtered (AOT40 = 0 in both years) and non-filtered (AOT40 = 9.7 in 2005 and 6.9 ppm h in 2006) open-top chambers. Alfalfa yield was reduced by O 3 (-33%) only in plants irrigated with salt-free water, while the increasing levels of soil salinity until 1.06 dS m -1 reduced both stomatal conductance and plant O 3 uptake, thus linearly reducing O 3 effects on yield. Therefore a reliable flux-based model for assessing the effects of O 3 on crop yield should take into account soil salinity. - Moderate saline stress can reduce ozone uptake and yield losses in alfalfa plants.

  6. Coupling genetics and proteomics to identify aphid proteins associated with vector-specific transmission of polerovirus (luteoviridae).

    Science.gov (United States)

    Yang, Xiaolong; Thannhauser, T W; Burrows, Mary; Cox-Foster, Diana; Gildow, Fred E; Gray, Stewart M

    2008-01-01

    Cereal yellow dwarf virus-RPV (CYDV-RPV) is transmitted specifically by the aphids Rhopalosiphum padi and Schizaphis graminum in a circulative nonpropagative manner. The high level of vector specificity results from the vector aphids having the functional components of the receptor-mediated endocytotic pathways to allow virus to transverse the gut and salivary tissues. Studies of F(2) progeny from crosses of vector and nonvector genotypes of S. graminum showed that virus transmission efficiency is a heritable trait regulated by multiple genes acting in an additive fashion and that gut- and salivary gland-associated factors are not genetically linked. Utilizing two-dimensional difference gel electrophoresis to compare the proteomes of vector and nonvector parental and F(2) genotypes, four aphid proteins (S4, S8, S29, and S405) were specifically associated with the ability of S. graminum to transmit CYDV-RPV. The four proteins were coimmunoprecipitated with purified RPV, indicating that the aphid proteins are capable of binding to virus. Analysis by mass spectrometry identified S4 as a luciferase and S29 as a cyclophilin, both of which have been implicated in macromolecular transport. Proteins S8 and S405 were not identified from available databases. Study of this unique genetic system coupled with proteomic analysis indicated that these four virus-binding aphid proteins were specifically inherited and conserved in different generations of vector genotypes and suggests that they play a major role in regulating polerovirus transmission.

  7. Expression of Pinellia pedatisecta Lectin Gene in Transgenic Wheat Enhances Resistance to Wheat Aphids

    OpenAIRE

    Xiaoliang Duan; Qiling Hou; Guoyu Liu; Xiaomeng Pang; Zhenli Niu; Xiao Wang; Yufeng Zhang; Baoyun Li; Rongqi Liang

    2018-01-01

    Wheat aphids are major pests during the seed filling stage of wheat. Plant lectins are toxic to sap-sucking pests such as wheat aphids. In this study, Pinellia pedatisecta agglutinin (ppa), a gene encoding mannose binding lectin, was cloned, and it shared 92.69% nucleotide similarity and 94% amino acid similarity with Pinellia ternata agglutinin (pta). The ppa gene, driven by the constitutive and phloem-specific ribulose bisphosphate carboxylase small subunit gene (rbcs) promoter in pBAC-rbcs...

  8. Identification of distinct quantitative trait loci associated with defence against the closely related aphids Acyrthosiphon pisum and A. kondoi in Medicago truncatula

    KAUST Repository

    Guo, Su-Min

    2012-03-21

    Aphids are a major family of plant insect pests. Medicago truncatula and Acyrthosiphon pisum (pea aphid, PA) are model species with a suite of resources available to help dissect the mechanism underlying plant-aphid interactions. A previous study focused on monogenic and relatively strong resistance in M. truncatula to PA and other aphid species. In this study a moderate resistance to PA was characterized in detail in the M. truncatula line A17 and compared with the highly susceptible line A20 and the more resistant line Jester. The results show that PA resistance in A17 involves both antibiosis and tolerance, and that resistance is phloem based. Quantitative trait locus (QTL) analysis using a recombinant inbred line (RIL) population (n=114) from a cross between A17 and A20 revealed that one locus, which co-segregated with AIN (Acyrthosiphon-induced necrosis) on chromosome 3, is responsible for the reduction of aphid biomass (indicator of antibiosis) for both PA and bluegreen aphid (BGA, A. kondoi), albeit to a lesser degree for PA than BGA. Interestingly, two independent loci on chromosomes 5 and 3 were identified for the plant biomass reduction (indicator of plant tolerance) by PA and BGA, respectively, demonstrating that the plant\\'s tolerance response to these two closely related aphid species is distinct. Together with previously identified major resistant (R) genes, the QTLs identified in this study are powerful tools to understand fully the spectrum of plant defence against sap-sucking insects and provide opportunities for breeders to generate effective and sustainable strategies for aphid control. 2012 The Author.

  9. Tritrophic associations and taxonomic notes on Lysiphlebus fabarum (Marshall (Hymenoptera: Braconidae: Aphidiinae, a keystone aphid parasitoid in Iran

    Directory of Open Access Journals (Sweden)

    Rakhshani Ehsan

    2013-01-01

    Full Text Available An investigation of host associations, distribution and types of reproduction (sexual, asexual of Lysiphlebus fabarum (Marshall across 20 provinces of Iran during 2006-2011 was undertaken. The parasitoid was reared from three groups of host aphids belonging to genera Aphis and Brachycaudus, and occasional host aphid genera. Aphis craccivora Koch was the most frequent host aphid for L. fabarum on various host plants, including economically important crops. The field sex ratio generally favored females, but in some cases, only thelytokous (uniparental populations were found. In those cases, the host was always an Aphis species. Specimens reared from Brachycaudus aphids were all biparental, indicating the presence of a sibling biological species. Overall analysis of diagnostic morphological characters in the forewing indicated intra-specific variability in forewing marginal setae as well as variations in length of the R1 vein. [Projekat Ministarstva nauke Republike Srbije, br. 43001

  10. Temperature dependent functional response of Diaeretiella rapae (Hymenoptera: Aphidiidae) to the cabbage aphid, Brevicoryne brassicae (Hemiptera: Aphididae)

    DEFF Research Database (Denmark)

    Moayeri, Hamid R. S.; Madadi, Hossein; Pouraskari, Hossein

    2013-01-01

    Diaeretiella rapae MacIntosh (Hymenoptera: Aphidiidae) is one of the most common and successful parasitoids of the cabbage aphid. The functional response of D. rapae towards cabbage aphids was examined in laboratory studies at three constant temperatures, 17°C, 25°C and 30°C. D. rapae exhibited a...

  11. Recent characterization of cowpea aphid-borne mosaic virus ...

    African Journals Online (AJOL)

    Woodiness disease is the most important disorder of passion fruit worldwide. The causal agent in Brazil is the Cowpea aphid-borne mosaic virus (CABMV), and despite the economic relevance of passion fruit for agriculture there have been recently very few studies about this virus in Brazil and worldwide. This work reveals ...

  12. Macrosiphoniella remaudierei, a new species of aphid on Helichrysum in Iran (Hemiptera, Aphididae).

    Science.gov (United States)

    Barbagallo, Sebastiano; Nieto Nafría, Juan M

    2016-01-01

    A new species of aphid, belonging to the genus Macrosiphoniella Del Guercio, 1911, is described using three samples collected in Iran on Helichrysum armenium (Asteraceae, Inuleae) by the late Prof. G. Remaudière. Both apterous and alate viviparous females of the new taxon, Macrosiphoniella remaudierei sp. n. , are described and compared to corresponding morphs of the closely allied Macrosiphoniella aetnensis and to other congeneric aphid species on Helichrysum in the Palaearctic region. Type specimens are now stored in the Muséum national d'Histoire naturelle in Paris.

  13. Macrosiphoniella remaudierei, a new species of aphid on Helichrysum in Iran (Hemiptera, Aphididae

    Directory of Open Access Journals (Sweden)

    Sebastiano Barbagallo

    2017-01-01

    Full Text Available A new species of aphid, belonging to the genus Macrosiphoniella Del Guercio, 1911, is described using three samples collected in Iran on Helichrysum armenium (Asteraceae, Inuleae by the late Prof. G. Remaudière. Both apterous and alate viviparous females of the new taxon, M. remaudierei sp. n., are described and compared to corresponding morphs of the closely allied M. aetnensis and to other congeneric aphid species on Helichrysum in the Palaearctic region. Type specimens are now stored in the Muséum national d’Histoire naturelle in Paris.

  14. Aphids transform and detoxify the mycotoxin deoxynivalenol via a type II biotransformation mechanism yet unknown in animals.

    Science.gov (United States)

    De Zutter, N; Audenaert, K; Arroyo-Manzanares, N; De Boevre, M; Van Poucke, C; De Saeger, S; Haesaert, G; Smagghe, G

    2016-12-08

    Biotransformation of mycotoxins in animals comprises phase I and phase II metabolisation reactions. For the trichothecene deoxynivalenol (DON), several phase II biotransformation reactions have been described resulting in DON-glutathiones, DON-glucuronides and DON-sulfates made by glutathione-S-transferases, uridine-diphosphoglucuronyl transferases and sulfotransferases, respectively. These metabolites can be easily excreted and are less toxic than their free compounds. Here, we demonstrate for the first time in the animal kingdom the conversion of DON to DON-3-glucoside (DON-3G) via a model system with plant pathogenic aphids. This phase II biotransformation mechanism has only been reported in plants. As the DON-3G metabolite was less toxic for aphids than DON, this conversion is considered a detoxification reaction. Remarkably, English grain aphids (Sitobion avenae) which co-occur with the DON producer Fusarium graminearum on wheat during the development of fusarium symptoms, tolerate DON much better and convert DON to DON-3G more efficiently than pea aphids (Acyrthosiphon pisum), the latter being known to feed on legumes which are no host for F. graminearum. Using a non-targeted high resolution mass spectrometric approach, we detected DON-diglucosides in aphids probably as a result of sequential glucosylation reactions. Data are discussed in the light of an eventual co-evolutionary adaptation of S. avenae to DON.

  15. Varietals resistance and susceptibility in mustard (brassica campestris l.) genotypes against aphid myzus persicae (sulzer) (homoptera: aphididae)

    International Nuclear Information System (INIS)

    Sarwar, M.; Ahmad, N.; Khan, G.Z.; Tofique, M.

    2009-01-01

    The exploitation of resistant cultivars is an imperative, simple, practical and flexible way to cope with insect pests incidence. Thirty genotypes of mustard (Brassica campestris L.) were tested for their resistance and susceptibility to aphid Myzus persicae (Sulzer) exposed under natural field conditions. Data on pest tolerance of genotypes were judged by quantitative traits such as number of aphids on each infested plant and mean dry weight of seeds per genotype. Studies observed the discrepancy in overall rates of pest invasion and seed yield contained by trailed mustard genotypes. Agati sarson (P), S-9-S-97-100/45 and S-9-S-97-100/45 were the least damaged genotypes showing their moderate resistance. Amongst other genotypes, MM-I/01-5, MM-I285 and MM-I/01-6 were the most damaged showing oversensitive response. Although the majority of genotypes were found vulnerable to pest, Agati sarson (P) and S-9-S-97-100/45 due to their lowest hypersensitive response toward aphid contamination and increased pods yield could be used for the development of essential resistance in mustard plant. A marked mode of damage inflicted by aphid on the crop was noticed and the abiotic factors contributing variations in aphid infestation levels during both growing seasons were determined. Knowledge about the host plant resistance investigated can facilitate growers to choose the most appropriate cultivars as pest control strategy. (author)

  16. How conserved are the bacterial communities associated with aphids? A detailed assessment of the Brevicoryne brassicae (Hemiptera: Aphididae) using 16S rDNA.

    Science.gov (United States)

    Clark, E L; Daniell, T J; Wishart, J; Hubbard, S F; Karley, A J

    2012-12-01

    Aphids harbor a community of bacteria that include obligate and facultative endosymbionts belonging to the Enterobacteriaceae along with opportunistic, commensal, or pathogenic bacteria. This study represents the first detailed analysis of the identity and diversity of the bacterial community associated with the cabbage aphid, Brevicoryne brassicae (L.). 16S rDNA sequence analysis revealed that the community of bacteria associated with B. brassicae was diverse, with at least four different bacterial community types detected among aphid lines, collected from widely dispersed sites in Northern Britain. The bacterial sequence types isolated from B. brassicae showed little similarity to any bacterial endosymbionts characterized in insects; instead, they were closely related to free-living extracellular bacterial species that have been isolated from the aphid gut or that are known to be present in the environment, suggesting that they are opportunistic bacteria transmitted between the aphid gut and the environment. To quantify variation in bacterial community between aphid lines, which was driven largely by differences in the proportions of two dominant bacterial orders, the Pseudomonales and the Enterobacteriales, we developed a novel real-time (Taqman) qPCR assay. By improving our knowledge of aphid microbial ecology, and providing novel molecular tools to examine the presence and function of the microbial community, this study forms the basis of further research to explore the influence of the extracellular bacterial community on aphid fitness, pest status, and susceptibility to control by natural enemies.

  17. Trade-Off Between Fitness Gain and Cost Determines Profitability of a Peach Aphid Parasitoid.

    Science.gov (United States)

    Khatri, Diwas; He, Xiong Z; Wang, Qiao

    2016-08-01

    Aphidius colemani (Viereck) (Hymenoptera: Aphidiidae) is commercially produced and utilized for biological control of peach aphid Myzus persicae (Sulzer) (Hemiptera: Aphididae) on greenhouse crops in many countries. To provide knowledge for the evaluation of parasitoid-host interactions and development of effective mass rearing programs, we investigated how and why host age or size affected fitness gain in A. colemani We show that the parasitoid was significantly more likely to encounter larger hosts and that an encounter almost always triggered an attack attempt. However, the attack attempt did not proportionally translate into oviposition because larger aphids had greater ability to defend themselves and the parasitoid spent more time in handling larger aphids. The host age at parasitization had no effect on emergence rates and sex ratio of parasitoid progeny, suggesting that pupae and larvae have similar survival rate in hosts of different ages and/or the parasitoid females do not adjust sex allocation based on host size. When parasitizing mid-aged hosts, the parasitoid gained maximum fitness for their progeny in developmental period, body size, and parasitism. Taking all findings together, we suggest that parasitizing mid-aged green peach aphid nymphs is most profitable for A. colemani. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Plant growth promoting rhizobacteria reduce aphid population and enhance the productivity of bread wheat.

    Science.gov (United States)

    Naeem, Muhammad; Aslam, Zubair; Khaliq, Abdul; Ahmed, Jam Nazir; Nawaz, Ahmad; Hussain, Mubshar

    2018-04-24

    Plant growth promoting rhizobacteria increase plant growth and give protection against insect pests and pathogens. Due to the negative impact of chemical pesticides on environment, alternatives to these chemicals are needed. In this scenario, the biological methods of pest control offer an eco-friendly and an attractive option. In this study, the effect of two plant growth promoting rhizobacterial strains (Bacillus sp. strain 6 and Pseudomonas sp. strain 6K) on aphid population and wheat productivity was evaluated in an aphid susceptible (Pasban-90) and resistant (Inqlab-91) wheat cultivar. The seeds were inoculated with each PGPR strain, separately or the combination of both. The lowest aphid population (2.1tiller -1 ), and highest plant height (85.8cm), number of spikelets per spike (18), grains per spike (44), productive tillers (320m -2 ), straw yield (8.6Mgha -1 ), and grain yield (4.8Mgha -1 ) were achieved when seeds were inoculated with Bacillus sp. strain 6+Pseudomonas sp. strain 6K. The grain yield of both varieties was enhanced by 35.5-38.9% with seed inoculation with both bacterial strains. Thus, the combine use of both PGPR strains viz. Bacillus sp. strain 6+Pseudomonas sp. strain 6K offers an attractive option to reduce aphid population tied with better wheat productivity. Copyright © 2018 Sociedade Brasileira de Microbiologia. Published by Elsevier Editora Ltda. All rights reserved.

  19. Effects of moisture content or particle size on the in situ degradability of maize silage and alfalfa haylage in lactating dairy cows

    OpenAIRE

    Yang Zou; Shuangzhao Dong; Yun Du; Shengli Li; Yajing Wang; Zhijun Cao

    2016-01-01

    A study using four Holstein cows with ruminal cannulas was conducted to evaluate the degradability of different moisture content or particle size of maize silage and alfalfa haylage. The maize silage (MS; 20-mm length) and alfalfa haylage (AH; 40-mm length) samples were wet (wet maize silage, MSW; wet alfalfa haylage, AHW), dried (dried maize silage, MSD; dried alfalfa haylage, AHD), or ground to pass through a 2.5-mm screen (dried ground maize silage, MSG; dried ground alfalfa haylage, AHG)....

  20. Local predators attack exotic aphid Brachycaudus divaricatae in Lithuania

    Czech Academy of Sciences Publication Activity Database

    Danilov, J.; Rakauskas, R.; Havelka, Jan; Starý, Petr

    2016-01-01

    Roč. 69, č. 2 (2016), s. 263-269 ISSN 1721-8861 Institutional support: RVO:60077344 Keywords : Prunus * Aphids * Brachycaudus divaricatae Subject RIV: EH - Ecology, Behaviour Impact factor: 1.051, year: 2016 http://www.bulletinofinsectology.org/pdfarticles/vol69-2016-263-269danilov.pdf

  1. The Effect of Temperature and Host Plant Resistance on Population Growth of the Soybean Aphid Biotype 1 (Hemiptera: Aphididae).

    Science.gov (United States)

    Hough, Ashley R; Nechols, James R; McCornack, Brian P; Margolies, David C; Sandercock, Brett K; Yan, Donglin; Murray, Leigh

    2017-02-01

    A laboratory experiment was conducted to evaluate direct and indirect effects of temperature on demographic traits and population growth of biotype 1 of the soybean aphid, Aphis glycines Matsumura. Our objectives were to better understand how temperature influences the expression of host plant resistance, quantify the individual and interactive effects of plant resistance and temperature on soybean aphid population growth, and generate thermal constants for predicting temperature-dependent development on both susceptible and resistant soybeans. To assess indirect (plant-mediated) effects, soybean aphids were reared under a range of temperatures (15-30 °C) on soybean seedlings from a line expressing a Rag1 gene for resistance, and life history traits were quantified and compared to those obtained for soybean aphids on a susceptible soybean line. Direct effects of temperature were obtained by comparing relative differences in the magnitude of life-history traits among temperatures on susceptible soybeans. We predicted that temperature and host plant resistance would have a combined, but asymmetrical, effect on soybean aphid fitness and population growth. Results showed that temperature and plant resistance influenced preimaginal development and survival, progeny produced, and adult longevity. There also appeared to be a complex interaction between temperature and plant resistance for survival and developmental rate. Evidence suggested that the level of plant resistance increased at higher, but not lower, temperature. Soybean aphids required about the same number of degree-days to develop on resistant and susceptible plants. Our results will be useful for making predictions of soybean aphid population growth on resistant plants under different seasonal temperatures. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  2. Insulin-related peptide 5 is involved in regulating embryo development and biochemical composition in pea aphid with wing polyphenism

    Directory of Open Access Journals (Sweden)

    Shan-Shan eGuo

    2016-02-01

    Full Text Available In aphids there is a fecundity-dispersal trade-off between wingless and winged morphs. Recent research on the molecular mechanism of wing morphs associated with dispersal reveals that insulin receptors in the insulin signaling (IS pathway regulate alteration of wing morphs in planthoppers. However, little is known about whether genes in the IS pathway are involved in developmental regulation in aphid nymphs with different wing morphs. In this study, we show that expression of the insulin-related peptide 5 gene (Apirp5 affects biochemical composition and embryo development of wingless pea aphids, Acyrthosiphon pisum. After comparing expression levels of major genes in the IS pathway between third instar winged and wingless nymphs, we found that Apirp5 showed higher expression in head and thorax of the wingless nymphs than in the winged nymphs. Although microinjection treatment affects physical performance in aphids, nymphs with RNA interference of Apirp5 had less weight, smaller embryo size and higher carbohydrate and protein contents compared to control group. Comparison between winged and wingless nymphs showed a similar trend. These results indicate that Apirp5 is involved in embryo development and metabolic regulation in wing dimorphic pea aphid.

  3. Aphid parasitoid (Hymenoptera:Braconidae: Aphidiinae) in wetland habitats in western Palearctic: key and associated aphid parasitoid guilds

    Czech Academy of Sciences Publication Activity Database

    Tomanović, Ž.; Starý, Petr; Kavallieratos, N. G.; Gagić, V.; Plećaš, M.; Janković, M.; Rakhshani, E.; Ćetković, A.; Petrović, A.

    2012-01-01

    Roč. 48, 1-2 (2012), s. 189-198 ISSN 0037-9271 Grant - others:The Ministry of Science and Technological Development of the Republic of Serbia(RS) 043001 Institutional research plan: CEZ:AV0Z50070508 Keywords : aphid parasitoids * tritrophic interactions * wetlands Subject RIV: EH - Ecology, Behaviour Impact factor: 0.529, year: 2012 http://zoologie.umh.ac.be/asef/pdf/2012_48_01_02/full/Tomanovic_et_al_2012_ASEF_48_1_2_189_198_full.pdf

  4. Identification of loci Associated with Resistance to Root-Rot Diseases in Autotetraploid Alfalfa using Genome-Wide Sequencing and Association Mapping

    Science.gov (United States)

    Alfalfa (Medicago sativa L.) is the world-wide forage crop. Changing trends to multipurpose uses increases demand for alfalfa. However, the production of alfalfa is challenged by endemic and emerging diseases. Identification of genes/loci controlling disease resistance will facilitate breeding for i...

  5. Study in mutation of alfalfa genome DNA due to low energy N+ implantation using RAPD

    International Nuclear Information System (INIS)

    Chen Roulei; Song Daojun; Yu Zengliang; Li Yufeng; Liang Yunzhang

    2001-01-01

    After implanted by various dosage N + beams, germination rate of alfalfa seeds appears to be saddle line with dosage increasing. The authors have studied in mutation of genome DNA due to low energy N + implantation, and concluded that 30 differential DNA fragments have been amplified by 8 primers (S 41 , S 42 , S 45 , S 46 , S 50 , S 52 , S 56 , S 58 ) in 100 primers, moreover, number of differential DNA fragments between CK and treatments increases with dosage. Consequently, low energy ion implantation can cause mutation of alfalfa genome DNA. The more dosage it is, the more mutation alfalfa will be

  6. Progress on researches of transgenic alfalfa

    International Nuclear Information System (INIS)

    Guo Huiqin; Wang Mi; Ren Weibo; Xu Zhu; Chen Libo

    2010-01-01

    In this paper, the progress on the researches of transgenic alfalfa in the past two decades had been reviewed in the aspects of regeneration system, transformation, improvement of the important traits and so on. Moreover, such problems as variation of transgene expression and safety of transgenic plant had also been discussed and propose had been given for the future research work. (authors)

  7. Accumulation and residue of napropamide in alfalfa (Medicago sativa) and soil involved in toxic response.

    Science.gov (United States)

    Cui, Li E; Yang, Hong

    2011-06-15

    Napropamide belongs to the amide herbicide family and widely used to control weeds in farmland. Intensive use of the herbicide has resulted in widespread contamination to ecosystems. The present study demonstrated an analysis on accumulation of the toxic pesticide napropamide in six genotypes of alfalfa (Medicago sativa), along with biological parameters and its residues in soils. Soil was treated with napropamide at 3 mg kg(-1) dry soil and alfalfa plants were cultured for 10 or 30 d, respectively. The maximum value for napropamide accumulation is 0.426 mg kg(-1) in shoots and 2.444 mg kg(-1) in roots. The napropamide-contaminated soil with alfalfa cultivation had much lower napropamide concentrations than the control (soil without alfalfa cultivation). Also, the content of napropamide residue in the rhizosphere was significantly lower than that in the non-rhizosphere soil. M. sativa exposed to 3 mg kg(-1) napropamide showed inhibited growth. Further analysis revealed that plants treated with napropamide accumulated more reactive oxygen species (O(2)(-) and H(2)O(2)) and less amounts of chlorophyll. However, not all cultivars showed oxidative injury, suggesting that the alfalfa cultivars display different tolerance to napropamide. Copyright © 2011 Elsevier B.V. All rights reserved.

  8. Changes of oxidase and hydrolase activities in pecan leaves elicited by black pecan aphid (Hemiptera: Aphididae) feeding.

    Science.gov (United States)

    Chen, Yigen; Ni, Xinzhi; Cottrell, Ted E; Wood, Bruce W; Buntin, G David

    2009-06-01

    The black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), is a foliar feeder of pecan, Carya illinoinensis (Wangenh.) K. Koch (Juglandaceae). The pest causes chlorosis of leaflet lamina, physiological damage to foliage and trees, and commonly limits the profitability of commercial pecan orchard enterprises. However, key aspects of this host-pest interaction are poorly understood. We report here the effects of M. caryaefoliae feeding on the foliar activity of oxidative (i.e., catalase, lipoxygenase [LOX]-1 and 3, and peroxidase) and hydrolytic (i.e., esterase) enzymes in relation to the degree of aphid resistance among pecan varieties. The 2-yr study showed that M. caryaefoliae-infested foliage exhibited elevated peroxidase activity only in susceptible ('Desirable', 'Sumner', and 'Schley'), but not in resistant ('Cape Fear', 'Gloria Grande', and 'Money Maker') genotypes. Susceptible genotypes also exhibited more severe leaf chlorosis in response to M. caryaefoliae feeding than the resistant genotypes; however, the aphid feeding did not influence catalase or esterase activity in all varieties, except the increase of esterase activity in Desirable and Gloria Grande. Melanocallis caryaefoliae feeding also influences activity of two lipoxygenase isozymes, with LOX3 being more frequently induced than LOX1. Foliar LOX3 activity was more frequently induced by M. caryaefoliae feeding in the moderately resistant 'Oconee' and highly resistant Money Maker and Cape Fear than in the susceptible genotypes. Therefore, the elevation of peroxidase is likely to be associated with aphid susceptibility and contributed to the severe leaf chlorosis, whereas the increase of LOX3 activity might be associated with aphid resistance in pecan. These findings contribute to our understanding of the etiology of M. caryaefoliae-elicited leaf chlorosis on pecan foliage. Such information may also be used to develop enzyme markers for identifying black pecan aphid resistance

  9. Fixed-Precision Sequential Sampling Plans for Estimating Alfalfa Caterpillar, Colias lesbia, Egg Density in Alfalfa, Medicago sativa, Fields in Córdoba, Argentina

    Science.gov (United States)

    Serra, Gerardo V.; Porta, Norma C. La; Avalos, Susana; Mazzuferi, Vilma

    2013-01-01

    The alfalfa caterpillar, Colias lesbia (Fabricius) (Lepidoptera: Pieridae), is a major pest of alfalfa, Medicago sativa L. (Fabales: Fabaceae), crops in Argentina. Its management is based mainly on chemical control of larvae whenever the larvae exceed the action threshold. To develop and validate fixed-precision sequential sampling plans, an intensive sampling programme for C. lesbia eggs was carried out in two alfalfa plots located in the Province of Córdoba, Argentina, from 1999 to 2002. Using Resampling for Validation of Sampling Plans software, 12 additional independent data sets were used to validate the sequential sampling plan with precision levels of 0.10 and 0.25 (SE/mean), respectively. For a range of mean densities of 0.10 to 8.35 eggs/sample, an average sample size of only 27 and 26 sample units was required to achieve a desired precision level of 0.25 for the sampling plans of Green and Kuno, respectively. As the precision level was increased to 0.10, average sample size increased to 161 and 157 sample units for the sampling plans of Green and Kuno, respectively. We recommend using Green's sequential sampling plan because it is less sensitive to changes in egg density. These sampling plans are a valuable tool for researchers to study population dynamics and to evaluate integrated pest management strategies. PMID:23909840

  10. Susceptibility of Aphelinus certus to foliar-applied insecticides currently or potentially registered for soybean aphid control.

    Science.gov (United States)

    Frewin, Andrew J; Schaafsma, Arthur W; Hallett, Rebecca H

    2012-02-01

    Soybean aphid, a serious economic pest of soybean in North America, is currently managed by applying non-selective foliar insecticides during outbreaks according to decision thresholds and crop maturity. Natural enemies, such as the parasitoid Aphelinus certus Yasnosh, potentially play an important role in suppressing soybean aphid. Using selective insecticides that preserve A. certus may enhance the biological control service they provide and thus prevent or reduce the severity of soybean aphid outbreaks. The toxicity of five insecticides (λ-cyhalothrin, dimethoate, flonicamid, mineral oil, spirotetramat) and the biopesticide Beauveria bassiana to A. certus was assessed. The LD50 values of λ-cyhalothrin and dimethoate were similar; however, the hazard quotient of dimethoate was greater than that of λ-cyhalothrin. In a screening bioassay, the descending order of toxicity for the recommended rates 48 h after application was dimethoate>λ-cyhalothrin>flonicamid>mineral oil>Beauveria bassiana>spirotetramat. Overall, λ-cyhalothrin and dimethoate were both harmful to A. certus. The other insecticides tested were harmless to A. certus and are potential candidates for inclusion in soybean aphid management programs. Copyright © 2011 Society of Chemical Industry.

  11. Effect of Intercropping Collard with Beans or Onions on Aphid ...

    African Journals Online (AJOL)

    chemical sprays, which has tended to result in pest resistance and pollution to the environment, This ... effects of intercropping and nitrogen fertilization on aphid population on collard and the yield ... :h~ cultivation and sale of collard (Brassica.

  12. Aphid (Myzus persicae) feeding on the parasitic plant dodder (Cuscuta australis) activates defense responses in both the parasite and soybean host.

    Science.gov (United States)

    Zhuang, Huifu; Li, Juan; Song, Juan; Hettenhausen, Christian; Schuman, Meredith C; Sun, Guiling; Zhang, Cuiping; Li, Jing; Song, Dunlun; Wu, Jianqiang

    2018-06-01

    Dodders (Cuscuta spp.) are shoot holoparasites, whose haustoria penetrate host tissues to enable fusion between the parasite and host vascular systems, allowing Cuscuta to extract water, nutrients and other molecules from hosts. Aphids are piercing-sucking herbivores that use specialized stylets to feed on phloem sap. Aphids are known to feed on Cuscuta, but how Cuscuta and its host plant respond to aphids attacking the parasite was unknown. Phytohormone quantification, transcriptomic analysis and bioassays were performed to determine the responses of Cuscuta australis and its soybean (Glycine max) hosts to the feeding of green peach aphid (GPA; Myzus persicae) on C. australis. Decreased salicylic acid levels and 172 differentially expressed genes (DEGs) were found in GPA-attacked C. australis, and the soybean hosts exhibited increased jasmonic acid contents and 1015 DEGs, including > 100 transcription factor genes. Importantly, GPA feeding on C. australis increased the resistance of the soybean host to subsequent feeding by the leafworm Spodoptera litura and soybean aphid Aphis glycines, resulting in 21% decreased leafworm mass and 41% reduced aphid survival rate. These data strongly suggest that GPA feeding on Cuscuta induces a systemic signal, which is translocated to hosts and activates defense against herbivores. © 2018 The Authors. New Phytologist © 2018 New Phytologist Trust.

  13. Crop growth in early spring and radiation use efficiency in alfalfa

    International Nuclear Information System (INIS)

    Akmal, M.; Farid, U.; Asim, M.; Farhatullah, A.; Raziuddin, A.

    2011-01-01

    The study was conducted at Agronomy Research Farm, KP Agricultural University Peshawar. Fifteen alfalfa lines (M. sativa L.) were compared for crop growth rate (CGR), biomass yield and radiation use efficiency (RUE). The previous year experiment was defoliated on March, 13 2006 at ground levels about 5 cm height. Fertilizer to the crop was applied every year in first week of March to yield 30, 60, and 30 kg ha/sup -1/ N, P, and K, respectively after defoliation. Periodic samples were harvested from one meter row length at two locations and oven dried at 70 degree C for about 36 h. Before samples, periodic leaf area index (LAI) was recorded with LI-2000 (LI-COR, USA) and subsequently light measurements were made using data logger (LI-1400, LI-COR, USA) and light sensors LI-190 and LI-191 (LI-COR, USA). The CGR showed variation in shapes and asymptotes for the different alfalfa lines which resulted differences in both fresh and dry matters yield at final sampling harvest. Alfalfa line Gramma-2 was the highest in dry matter yield (110 g m-2) followed by Flewish-pop (107 g m-2). Alfalfa line Pumha with 74 g m-2 was the lowest in dry matter yield. Differences were observed in LAI (p<0.05). High dry matter yield of alfalfa line Gramma-2 was due to higher LAI which was associated to highest leaf fraction (38%). Differences in RUE were also observed among the lines. Flewish-pop was the highest in RUE (0.20 g DM MJ-2 PAR absorbed), followed by Gramma-2 (0.18 g DM MJ-2 PAR absorbed). Mean CGR and RUE of the different lines showed association with dry matter yield of which the lateral one showed a strong association compared with the earlier one. We conclude that higher RUE than CGR is important for the line/variety to get quality fodder production. (author)

  14. Is the response of aphids to alarm pheromone stable?

    Czech Academy of Sciences Publication Activity Database

    Thieme, T.; Dixon, Anthony F. G.

    2015-01-01

    Roč. 139, č. 10 (2015), s. 741-746 ISSN 0931-2048 R&D Projects: GA MŠk(CZ) LO1415 Institutional support: RVO:67179843 Keywords : (E)-β-farnesene * dropping response * habituation * Leguminosae * pea aphid Subject RIV: EH - Ecology, Behaviour Impact factor: 1.517, year: 2015

  15. Behavioral evidence for local reduction of aphid-induced resistance

    NARCIS (Netherlands)

    Prado, E.; Tjallingii, W.F.

    2007-01-01

    Twenty-five aphids of three different species, Brevicoryne brassicae L, Myzus persicae Schulzer, and Rhopalosiphum padi L(Hemiptera: Aphididae) were each allowed to infest leaves of a young plant of their respective host plant species for 4 days, except that the oldest expanded leaf (the `systemic¿

  16. Impact of Bee Species and Plant Density on Alfalfa Pollination and Potential for Gene Flow

    Directory of Open Access Journals (Sweden)

    Johanne Brunet

    2010-01-01

    Full Text Available In outcrossing crops like alfalfa, various bee species can contribute to pollination and gene flow in seed production fields. With the increasing use of transgenic crops, it becomes important to determine the role of these distinct pollinators on alfalfa pollination and gene flow. The current study examines the relative contribution of honeybees, three bumble bee species, and three solitary bee species to pollination and gene flow in alfalfa. Two wild solitary bee species and one wild bumble bee species were best at tripping flowers, while the two managed pollinators commonly used in alfalfa seed production, honeybees and leaf cutting bees, had the lowest tripping rate. Honeybees had the greatest potential for gene flow and risk of transgene escape relative to the other pollinators. For honeybees, gene flow and risk of transgene escape were not affected by plant density although for the three bumble bee species gene flow and risk of transgene escape were the greatest in high-density fields.

  17. 77 FR 46373 - Field Release of Aphelinus glycinis for the Biological Control of the Soybean Aphid in the...

    Science.gov (United States)

    2012-08-03

    ... Inspection Service [Docket No APHIS-2012-0061] Field Release of Aphelinus glycinis for the Biological Control... for the biological control of the soybean aphid, Aphis glycines, in the continental United States. We... glycinis for the Biological Control of the Soybean Aphid in the Continental United States'' (March 2012...

  18. Preference and life history traits of Aphelinus abdominalis (Hymenoptera: Aphelinidae) when offered different development stages of the lettuce aphid Nasonovia ribisnigri (Hemiptera: Aphididae)

    DEFF Research Database (Denmark)

    Shrestha, Govinda; Skovgård, Henrik; Steenberg, Tove

    2015-01-01

    stages of the lettuce aphid were exposed for parasitism compared with older developmental stages. This pattern was supported in the choice experiment where significantly more 2nd instar lettuce aphids were parasitised than alatoid 4th instars, with Manly’s preference index (mean ± SE) for the former...... %) were found across all host stages of the lettuce aphid....

  19. Non-pest prey do not disrupt aphid predation by a web-building spider.

    Science.gov (United States)

    Welch, K D; Whitney, T D; Harwood, J D

    2016-02-01

    A generalist predator's ability to contribute to biological control is influenced by the decisions it makes during foraging. Predators often use flexible foraging tactics, which allows them to pursue specific types of prey at the cost of reducing the likelihood of capturing other types of prey. When a pest insect has low nutritional quality or palatability for a predator, the predator is likely to reject that prey in favour of pursuing alternative, non-pest prey. This is often thought to limit the effectiveness of generalist predators in consuming aphids, which are of low nutritional quality for many generalist predators. Here, we report behavioural assays that test the hypothesis that the generalist predator, Grammonota inornata (Araneae: Linyphiidae), preferentially forages for a non-pest prey with high nutritional quality (springtails), and rejects a pest prey with low nutritional quality (aphids). In no-choice assays, molecular gut-content analysis revealed that spiders continued to feed on the low-quality aphids at high rates, even when high-quality springtails were readily available. When provided a choice between aphids and springtails in two-way choice tests, spiders did not show the expected preference for springtails. Decision-making by spiders during foraging therefore appears to be sub-optimal, possibly because of attraction to the less frequently encountered of two preys as part of a dietary diversification strategy. These results indicate that behavioural preferences alone do not necessarily compromise the pest-suppression capacity of natural enemies: even nutritionally sub-optimal pest prey can potentially be subject to predation and suppression by natural enemies.

  20. Salt Stress Effects on Secondary Metabolites of Cotton in Relation to Gene Expression Responsible for Aphid Development.

    Directory of Open Access Journals (Sweden)

    Qi Wang

    Full Text Available Many secondary metabolites have insecticidal efficacy against pests and may be affected by abiotic stress. However, little is known of how plants may respond to such stress as pertains the growth and development of pests. The objective of this study was to determine if and how salt stress on cotton plants affects the population dynamics of aphids. The NaCl treatment (50 mM, 100 mM, 150 mM and 200 mM increased contents of gossypol in cotton by 26.8-51.4%, flavonoids by 22.5-37.6% and tannic by 15.1-24.3% at 7-28 d after salt stress. Compared with non-stressed plants, the population of aphids on 150 and 200 mM NaCl stressed plants was reduced by 46.4 and 65.4% at 7d and by 97.3 and 100% at 14 days after infestation. Reductions in aphid population were possibly attributed to the elevated secondary metabolism under salt stress. A total of 796 clones for aphids transcriptome, 412 clones in the positive- library (TEST and 384 clones in the reverse-library (Ck, were obtained from subtracted cDNA libraries and sequenced. Gene ontology (GO functional classification and KEGG pathway analysis showed more genes related to fatty acid and lipid biosynthesis, and fewer genes related to carbohydrate metabolism, amino acid metabolism, energy metabolism and cell motility pathways in TEST than in Ck library, which might be the reason of aphids population reduction. A comparative analysis with qRT-PCR indicated high expression of transcripts CYP6A14, CYP6A13, CYP303A1, NADH dehydrogenase and fatty acid synthase in the TEST group. However, CYP307A1 and two ecdysone-induced protein genes were down regulated. The results indicate that genes of aphids related to growth and development can express at a higher level in reaction to the enhanced secondary metabolism in cotton under salinity stress. The expression of CYP307A1 was positively correlated with the population dynamics of aphids since it was involved in ecdysone synthesis.

  1. Elevated CO2 increases R gene-dependent resistance of Medicago truncatula against the pea aphid by up-regulating a heat shock gene.

    Science.gov (United States)

    Sun, Yucheng; Guo, Huijuan; Yuan, Erliang; Ge, Feng

    2018-03-01

    Resistance against pathogens and herbivorous insects in many plant results from the expression of resistance (R) genes. Few reports, however, have considered the effects of elevated CO 2 on R gene-based resistance in plants. The current study determined the responses of two near isogenic Medicago truncatula genotypes (Jester has an R gene and A17 does not) to the pea aphid and elevated CO 2 in open-top chambers in the field. Aphid abundance, mean relative growth rate and feeding efficiency were increased by elevated CO 2 on A17 plants but were reduced on Jester plants. According to proteomic and gene expression data, elevated CO 2 enhanced pathogen-associated molecular pattern (PAMP)-triggered immunity (PTI) but decreased the effector-triggered immunity (ETI) in aphid-infested A17 plants. For aphid-infested Jester plants, by contrast, elevated CO 2 enhanced the ETI-related heat shock protein (HSP) 90 and its co-chaperones, the jasmonic acid (JA) signaling pathway, and ubiquitin-mediated proteolysis. In a loss-of-function experiment, silencing of the HSP90 gene in Jester plants impaired the JA signaling pathway and ubiquitin-mediated proteolysis against the aphid under ambient CO 2 , and negated the increased resistance against the aphid under elevated CO 2 . Our results suggest that increases in expression of HSP90 are responsible for the enhanced resistance against the aphid under elevated CO 2 . © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  2. Parasitoids (Hymenoptera: Braconidae: Aphidiinae) attacking aphids feeding on solanaceae and cucurbitaceae crops in Southeastern Europe: Aphidiine-aphid-plant associations and key

    Czech Academy of Sciences Publication Activity Database

    Kavallieratos, N. G.; Tomanović, Ž.; Starý, Petr; Žikić, V.; Petrović-Obradović, O.

    2010-01-01

    Roč. 103, č. 2 (2010), s. 153-164 ISSN 0013-8746 R&D Projects: GA AV ČR IBS5007102 Grant - others:The Ministry of Science and Environment Protection(CS) 143006B Institutional research plan: CEZ:AV0Z50070508 Keywords : Aphidiinae * aphids * Solanaceae Subject RIV: EH - Ecology, Behaviour Impact factor: 1.031, year: 2010

  3. Coupling Genetics and Proteomics To Identify Aphid Proteins Associated with Vector-Specific Transmission of Polerovirus (Luteoviridae)▿

    Science.gov (United States)

    Yang, Xiaolong; Thannhauser, T. W.; Burrows, Mary; Cox-Foster, Diana; Gildow, Fred E.; Gray, Stewart M.

    2008-01-01

    Cereal yellow dwarf virus-RPV (CYDV-RPV) is transmitted specifically by the aphids Rhopalosiphum padi and Schizaphis graminum in a circulative nonpropagative manner. The high level of vector specificity results from the vector aphids having the functional components of the receptor-mediated endocytotic pathways to allow virus to transverse the gut and salivary tissues. Studies of F2 progeny from crosses of vector and nonvector genotypes of S. graminum showed that virus transmission efficiency is a heritable trait regulated by multiple genes acting in an additive fashion and that gut- and salivary gland-associated factors are not genetically linked. Utilizing two-dimensional difference gel electrophoresis to compare the proteomes of vector and nonvector parental and F2 genotypes, four aphid proteins (S4, S8, S29, and S405) were specifically associated with the ability of S. graminum to transmit CYDV-RPV. The four proteins were coimmunoprecipitated with purified RPV, indicating that the aphid proteins are capable of binding to virus. Analysis by mass spectrometry identified S4 as a luciferase and S29 as a cyclophilin, both of which have been implicated in macromolecular transport. Proteins S8 and S405 were not identified from available databases. Study of this unique genetic system coupled with proteomic analysis indicated that these four virus-binding aphid proteins were specifically inherited and conserved in different generations of vector genotypes and suggests that they play a major role in regulating polerovirus transmission. PMID:17959668

  4. Responses to ozone pollution of alfalfa exposed to increasing salinity levels

    Energy Technology Data Exchange (ETDEWEB)

    Maggio, Albino; Chiaranda, Fabrizio Quaglietta; Cefariello, Roberto [DIAAT, Naples University Federico II, via Universita 100, 80055 Portici (Italy); Fagnano, Massimo, E-mail: fagnano@unina.i [DIAAT, Naples University Federico II, via Universita 100, 80055 Portici (Italy)

    2009-05-15

    Stomatal closure and biosynthesis of antioxidant molecules are two fundamental components of the physiological machinery that lead to stress adaptation during plant's exposure to salinity. Since high stomatal resistance may also contribute in counteracting O{sub 3} damages, we hypothesized that soil salinization may increase O{sub 3} tolerance of crops. An experiment was performed with alfalfa grown in filtered (AOT40 = 0 in both years) and non-filtered (AOT40 = 9.7 in 2005 and 6.9 ppm h in 2006) open-top chambers. Alfalfa yield was reduced by O{sub 3} (-33%) only in plants irrigated with salt-free water, while the increasing levels of soil salinity until 1.06 dS m{sup -1} reduced both stomatal conductance and plant O{sub 3} uptake, thus linearly reducing O{sub 3} effects on yield. Therefore a reliable flux-based model for assessing the effects of O{sub 3} on crop yield should take into account soil salinity. - Moderate saline stress can reduce ozone uptake and yield losses in alfalfa plants.

  5. Infestation of potato (Solanum tuberosum L.) by the peach-potato aphid (Myzus persicae Sulzer) alters cellular redox status and is influenced by ascorbate.

    Science.gov (United States)

    Kerchev, Pavel I; Fenton, Brian; Foyer, Christine H; Hancock, Robert D

    2012-02-01

    The peach-potato aphid (Myzus persicae Sulzer) is a major pest of potato (Solanum tuberosum L.) but the molecular characterization of this interaction particularly with regard to oxidants and antioxidants remains to be undertaken. Aphid colonies reared on potato leaves containing high ascorbate were twice the size of those grown on leaves with low ascorbate. Infestation-dependent decreases in the abundance of key transcripts such as chloroplastic FeSOD, peroxisomal catalase 2, PR1 and JAZ1 preceded detectable leaf H(2)O(2) or polyphenol accumulation. The leaf glutathione pool was increased 48 h after infestation, but the amount of ascorbate was unchanged. The ascorbate/dehydroacorbate (DHA) ratio was lower at 48 h but the ratio of reduced glutathione (GSH) to oxidized glutathione (GSSG) was unchanged. While DHA reductase and GSSG reductase activities were unaffected by aphid feeding, non-specific peroxidase activities were enhanced 48 h following aphid infestation. Brown ethanol-insoluble deposits were observed close to leaf veins following aphid infestation. Taken together, the results demonstrate that high ascorbate favours aphid colony expansion and that perturbations in the leaf antioxidant system are intrinsic to the potato leaf response to aphids. Moreover, these changes together with the induction of hormone-related transcripts precede the deposition of defence-associated oxidized polyphenols along the stylet track. © 2011 Blackwell Publishing Ltd.

  6. Non-pathogenic rhizobacteria interfere with the attraction of parasitoids to aphid-induced plant volatiles via jasmonic acid signalling.

    Science.gov (United States)

    Pineda, Ana; Soler, Roxina; Weldegergis, Berhane T; Shimwela, Mpoki M; VAN Loon, Joop J A; Dicke, Marcel

    2013-02-01

    Beneficial soil-borne microbes, such as mycorrhizal fungi or rhizobacteria, can affect the interactions of plants with aboveground insects at several trophic levels. While the mechanisms of interactions with herbivorous insects, that is, the second trophic level, are starting to be understood, it remains unknown how plants mediate the interactions between soil microbes and carnivorous insects, that is, the third trophic level. Using Arabidopsis thaliana Col-0 and the aphid Myzus persicae, we evaluate here the underlying mechanisms involved in the plant-mediated interaction between the non-pathogenic rhizobacterium Pseudomonas fluorescens and the parasitoid Diaeretiella rapae, by combining ecological, chemical and molecular approaches. Rhizobacterial colonization modifies the composition of the blend of herbivore-induced plant volatiles. The volatile blend from rhizobacteria-treated aphid-infested plants is less attractive to an aphid parasitoid, in terms of both olfactory preference behaviour and oviposition, than the volatile blend from aphid-infested plants without rhizobacteria. Importantly, the effect of rhizobacteria on both the emission of herbivore-induced volatiles and parasitoid response to aphid-infested plants is lost in an Arabidopsis mutant (aos/dde2-2) that is impaired in jasmonic acid production. By modifying the blend of herbivore-induced plant volatiles that depend on the jasmonic acid-signalling pathway, root-colonizing microbes interfere with the attraction of parasitoids of leaf herbivores. © 2012 Blackwell Publishing Ltd.

  7. Photosynthate partitioning in alfalfa before harvest and during regrowth

    International Nuclear Information System (INIS)

    Cralle, H.T.; Heichel, G.H.

    1988-01-01

    During the harvest regrowth cycle of alfalfa (Medicago sativa L.) plants, factors such as source to sink distance, sink size, and inter-organ competition continually change. However, consequent changes in the pattern of photosynthate partitioning from leaves to other organs are poorly understood. The authors objective was to examine photosynthate partitioning from upper and lower alfalfa leaves at intervals before herbage harvest and during regrowth after harvest. The uppermost or lowest fully expanded leaf on the longest or dominant stem was labeled with 14 CO 2 . After a 24-h translocation period, the plants were divided into various organs to determine distribution of the radiocarbon. At that time, the upper leaf preferentially partitioned photosynthate to the shoot apex, unexpanded leaves and auxillary shoots of the dominant shoot, whereas the lower leaf preferentially distributed photosynthate to the crown shoots, crown, root, and nodules. Expressions of 14 C partitioning were affected differently by organ mass. While the smallest organs such as nodules and unexpanded leaves always ranked higher for 14 C based on relative specific activity, the largest organs such as roots and crown shoots accumulated the largest percentage of total plant recovered radioactivity. The results illustrate the importance of growth stage and leaf position in photosynthate partitioning in alfalfa and the dominance of herbage meristems for current photosynthate during regrowth

  8. Neonicotinoid binding, toxicity and expression of nicotinic acetylcholine receptor subunits in the aphid Acyrthosiphon pisum.

    Directory of Open Access Journals (Sweden)

    Emiliane Taillebois

    Full Text Available Neonicotinoid insecticides act on nicotinic acetylcholine receptor and are particularly effective against sucking pests. They are widely used in crops protection to fight against aphids, which cause severe damage. In the present study we evaluated the susceptibility of the pea aphid Acyrthosiphon pisum to the commonly used neonicotinoid insecticides imidacloprid (IMI, thiamethoxam (TMX and clothianidin (CLT. Binding studies on aphid membrane preparations revealed the existence of high and low-affinity binding sites for [3H]-IMI (Kd of 0.16 ± 0.04 nM and 41.7 ± 5.9 nM and for the nicotinic antagonist [125I]-α-bungarotoxin (Kd of 0.008 ± 0.002 nM and 1.135 ± 0.213 nM. Competitive binding experiments demonstrated that TMX displayed a higher affinity than IMI for [125I]-α-bungarotoxin binding sites while CLT affinity was similar for both [125I]-α-bungarotoxin and [3H]-IMI binding sites. Interestingly, toxicological studies revealed that at 48 h, IMI (LC50 = 0.038 µg/ml and TMX (LC50 = 0.034 µg/ml were more toxic than CLT (LC50 = 0.118 µg/ml. The effect of TMX could be associated to its metabolite CLT as demonstrated by HPLC/MS analysis. In addition, we found that aphid larvae treated either with IMI, TMX or CLT showed a strong variation of nAChR subunit expression. Using semi-quantitative PCR experiments, we detected for all insecticides an increase of Apisumα10 and Apisumβ1 expressions levels, whereas Apisumβ2 expression decreased. Moreover, some other receptor subunits seemed to be differently regulated according to the insecticide used. Finally, we also demonstrated that nAChR subunit expression differed during pea aphid development. Altogether these results highlight species specificity that should be taken into account in pest management strategies.

  9. Ultrastructure of compatible and incompatible interactions in phloem sieve elements during the stylet penetration by cotton aphids in melon

    NARCIS (Netherlands)

    Garzo, E.; Fernández-Pascual, Mercedes; Morcillo, Cesar; Fereres, Alberto; Gómez-Guillamón, M.L.; Tjallingii, W.F.

    2017-01-01

    Resistance of the melon line TGR-1551 to the aphid Aphis gossypii is based on preventing aphids from ingesting phloem sap. In electrical penetration graphs (EPGs), this resistance has been characterized with A. gossypii showing unusually long phloem salivation periods (waveform E1) mostly

  10. Efficacy of mineral oil combined with insecticides for the control of aphid virus vectors to reduce potato virus Y infections in seed potatoes (Solanum tuberosum)

    DEFF Research Database (Denmark)

    Hansen, Lars M.; Nielsen, Steen L.

    2012-01-01

    Aphids are major vectors of plant viruses. Potato virus Y (PVY) is the most important aphid-transmitted virus affecting potato crops in Denmark. Because of a changed seed potato growing strategy, the seed potato area in Denmark is changing from regions with a low average temperature to regions...... with a higher average temperature. This means that the aphids may infest the potato crops earlier and the population development of the aphids may be faster, and consequently PVY may more easily become epidemic in seed potato crops. With a view to reducing the spread of PVY a 3-year experiment was carried out...... with a combination of mineral oil and insecticides. In 2005 and 2007 when a very high number of aphids were present, nearly all plants were infected with PVY. In 2006 with a lower number of aphids a smaller proportion of the plants were infected, and a tendency to a lower PVY incidence in mineral-oil treated plots...

  11. First report of Fusarium wilt of alfalfa caused by Fusarium oxysporum f. sp. medicaginis in Wisconsin

    Science.gov (United States)

    Fusarium wilt, caused by Fusarium oxysporum f. sp. medicaginis, is an economically important vascular disease of alfalfa (Medicago sativa) throughout the world. Alfalfa plants with foliar wilt symptoms and reddish-brown arcs in roots consistent with Fusarium wilt were observed in disease assessment ...

  12. A comparison of ground beetle assemblages (Coleoptera: Carabidae in conventionally and ecologically managed alfalfa fields

    Directory of Open Access Journals (Sweden)

    P. Kolařík

    2014-12-01

    Full Text Available From 2007-2011, the occurrence of ground beetles (Coleoptera: Carabidae was studied using emergence traps in two differently managed alfalfa fields in the Czech Republic - a conventional and an ecological production system. In total, 784 specimens of ground beetles representing 58 species were trapped in these two alfalfa fields in South Moravia. A slightly higher number of specimens were trapped in the conventionally managed than in the ecological alfalfa stand (404 vs 380, respectively. In the conventionally managed alfalfa stand, the number of species was also higher than in the ecological stand (45 vs 40, respectively. With the exception of 2007 and 2009, Simpson’s indices of diversity were higher in the conventional stand than in the ecological in all study years. Shannon’s index was higher in the conventional alfalfa field in 2008, 2009, and 2011. Regarding distribution, species classified into group E (i.e., those without special demands on the type and quality of their habitat dominated in both types of management throughout the experimental period. The incidence of species classified into group R (i.e., those with narrow ecological amplitude was very low; i.e., only four species. These ground beetle species are included in the Red List of Threatened Species of the Czech Republic, and all of them (i.e. Acupalpus suturalis, Calosoma auropunctatum, Cicindela germanica and Ophonus cribricollis are listed as vulnerable.

  13. 7 CFR 202.44 - Proceedings under section 305(b) to determine whether foreign alfalfa or red clover seed is not...

    Science.gov (United States)

    2010-01-01

    ... foreign alfalfa or red clover seed is not adapted for general agricultural use in the United States. 202... Proceedings under section 305(b) to determine whether foreign alfalfa or red clover seed is not adapted for... for the purpose of determining whether seed of alfalfa or red clover from any foreign country or...

  14. Overexpression of GsZFP1 enhances salt and drought tolerance in transgenic alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Tang, Lili; Cai, Hua; Ji, Wei; Luo, Xiao; Wang, Zhenyu; Wu, Jing; Wang, Xuedong; Cui, Lin; Wang, Yang; Zhu, Yanming; Bai, Xi

    2013-10-01

    GsZFP1 encodes a Cys2/His2-type zinc-finger protein. In our previous study, when GsZFP1 was heterologously expressed in Arabidopsis, the transgenic Arabidopsis plants exhibited enhanced drought and cold tolerance. However, it is still unknown whether GsZFP1 is also involved in salt stress. GsZFP1 is from the wild legume Glycine soja. Therefore, the aims of this study were to further elucidate the functions of the GsZFP1 gene under salt and drought stress in the forage legume alfalfa and to investigate its biochemical and physiological functions under these stress conditions. Our data showed that overexpression of GsZFP1 in alfalfa resulted in enhanced salt tolerance. Under high salinity stress, greater relative membrane permeability and malondialdehyde (MDA) content were observed and more free proline and soluble sugars accumulated in transgenic alfalfa than in the wild-type (WT) plants; in addition, the transgenic lines accumulated less Na(+) and more K(+) in both the shoots and roots. Overexpression of GsZFP1 also enhanced the drought tolerance of alfalfa. The fold-inductions of stress-responsive marker gene expression, including MtCOR47, MtRAB18, MtP5CS, and MtRD2, were greater in transgenic alfalfa than those of WT under drought stress conditions. In conclusion, the transgenic alfalfa plants generated in this study could be used for farming in salt-affected as well as arid and semi-arid areas. Copyright © 2013 Elsevier Masson SAS. All rights reserved.

  15. Pepo aphid-borne yellows virus: a new species in the genus Polerovirus.

    Science.gov (United States)

    Ibaba, Jacques D; Laing, Mark D; Gubba, Augustine

    2017-02-01

    Pepo aphid-borne yellows virus (PABYV) has been proposed as a putative representative of a new species in the genus Polerovirus in the family Luteoviridae. The genomes of two South African (SA) isolates of cucurbit-infecting PABYV were described in this record. Total RNA, extracted from a pattypan (Cucurbita pepo L.) and a baby marrow (C. pepo L.) leaf samples, was subjected to next-generation sequencing (NGS) on the HiSeq Illumina platform. Sanger sequencing was subsequently used to authenticate the integrity of PABYV's genome generated from de novo assembly of the NGS data. PABYV genome of SA isolates consists of 5813 nucleotides and displays an organisation typical of poleroviruses. Genome sequence comparisons of the SA PABYV isolates to other poleroviruses support the classification of PABYV as a new species in the genus Polerovirus. Recombination analyses showed that PABYV and Cucurbit aphid-borne yellows virus (CABYV) shared the same ancestor for the genome part situated between breaking points. Phylogenetic analyses of the RNA-dependent RNA polymerase and the coat protein genes showed that SA PABYV isolates shared distant relationship with CABYV and Suakwa aphid-borne yellows virus. Based on our results, we propose that PABYV is a distinct species in the genus Polerovirus.

  16. Expression of an (E-β-farnesene synthase gene from Asian peppermint in tobacco affected aphid infestation

    Directory of Open Access Journals (Sweden)

    Xiudao Yu

    2013-10-01

    Full Text Available Aphids are major agricultural pests that cause significant yield losses in crop plants each year. (E-β-farnesene (EβF is the main or only component of an alarm pheromone involved in chemical communication within aphid species and particularly in the avoidance of predation. EβF also occurs in the essential oil of some plant species, and is catalyzed by EβF synthase. By using oligonucleotide primers designed from the known sequence of an EβF synthase gene from black peppermint (Mentha × piperita, two cDNA sequences, MaβFS1 and MaβFS2, were isolated from Asian peppermint (Mentha asiatica. Expression pattern analysis showed that the MaβFS1 gene exhibited higher expression in flowers than in roots, stems and leaves at the transcriptional level. Overexpression of MaβFS1 in tobacco plants resulted in emission of pure EβF ranging from 2.62 to 4.85 ng d− 1 g− 1 of fresh tissue. Tritrophic interactions involving peach aphids (Myzus persicae, and predatory lacewing (Chrysopa septempunctata larvae demonstrated that transgenic tobacco expressing MaβFS1 had lower aphid infestation. This result suggested that the EβF synthase gene from Asian peppermint could be a good candidate for genetic engineering of agriculturally important crop plants.

  17. Selective lignin downregulation leads to constitutive defense response expression in alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Gallego-Giraldo, Lina; Jikumaru, Yusuke; Kamiya, Yuji; Tang, Yuhong; Dixon, Richard A

    2011-05-01

    • Downregulation of hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase (HCT) in alfalfa (Medicago sativa) reduces lignin levels and improves forage quality and saccharification efficiency for bioethanol production. However, the plants have reduced stature. It was previously reported that HCT-down-regulated Arabidopsis have impaired auxin transport, but this has recently been disproved. • To address the basis for the phenotypes of lignin-modified alfalfa, we measured auxin transport, profiled a range of metabolites including flavonoids and hormones, and performed in depth transcriptome analyses. • Auxin transport is unaffected in HCT antisense alfalfa despite increased flavonoid biosynthesis. The plants show increased cytokinin and reduced auxin levels, and gibberellin levels and sensitivity are both reduced. Levels of salicylic, jasmonic and abscisic acids are elevated, associated with massive upregulation of pathogenesis and abiotic stress-related genes and enhanced tolerance to fungal infection and drought. • We suggest that HCT downregulated alfalfa plants exhibit constitutive activation of defense responses, triggered by release of bioactive cell wall fragments and production of hydrogen peroxide as a result of impaired secondary cell wall integrity. © 2011 The Authors. New Phytologist © 2011 New Phytologist Trust.

  18. Development of glyphosate-resistant alfalfa (Medicago sativa L.) upon transformation with the GR79Ms gene encoding 5-enolpyruvylshikimate-3-phosphate synthase.

    Science.gov (United States)

    Yi, Dengxia; Ma, Lin; Lin, Min; Li, Cong

    2018-07-01

    The glyphosate-resistant gene, GR79Ms, was successfully introduced into the genome of alfalfa. The transgenic events may serve as novel germplasm resources in alfalfa breeding. Weed competition can reduce the alfalfa yield, generating new alfalfa germplasm with herbicide resistance is essential. To obtain transgenic alfalfa lines with glyphosate resistance, a new synthetic glyphosate-resistant gene GR79Ms encoding 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) was introduced into alfalfa germplasm by Agrobacterium tumefaciens-mediated transformation. In total, 67 transformants were obtained. PCR and Southern blot analyses confirmed that GR79Ms was successfully inserted into the genome of alfalfa. Reverse transcription-PCR and western blot analyses further demonstrated the expression of GR79Ms and its product, GR79Ms EPSPS. Moreover, two homozygous transgenic lines were developed in the T 2 generation by means of molecular-assisted selection. Herbicide tolerance spray tests showed that the transgenic plants T 0 -GR1, T 0 -GR2, T 0 -GR3 and two homozygous lines were able to tolerate fourfold higher commercial usage of glyphosate than non-transgenic plants.

  19. How the use of nitrogen fertiliser may switch plant suitability for aphids: the case of Miscanthus, a promising biomass crop, and the aphid pest Rhopalosiphum maidis.

    Science.gov (United States)

    Bogaert, Florent; Chesnais, Quentin; Catterou, Manuella; Rambaud, Caroline; Doury, Géraldine; Ameline, Arnaud

    2017-08-01

    The use of nitrogen fertiliser in agrosystems can alter plant nitrogen and consequently improve nutrient availability for herbivores, potentially leading to better performance for herbivores and higher pest pressure in the field. We compared, in laboratory conditions, the effects of nitrogen fertilisation on a promising biomass crop, Miscanthus × giganteus, and its parents M. sinensis and M. sacchariflorus. The plant-mediated effects were compared on the second trophic level, the green corn leaf aphid Rhopalosiphum maidis. Results showed that the biomass and leaf C:N ratio of M. sinensis plants treated with nitrogen fertiliser were significantly greater than those of non-treated plants. As regards M. × giganteus and M. sacchariflorus, the only reported change was a significantly smaller leaf C:N ratio for treated M. sacchariflorus compared with non-treated plants. Surprisingly, nitrogen fertilisation had opposite effects on plant-herbivore interactions. Following nitrogen treatments, M. sinensis was less suitable in terms of intrinsic rate of increase for R. maidis, the feeding behaviour of which was negatively affected, while M. sacchariflorus and M. × giganteus exhibited greater suitability in terms of aphid weight. Nitrogen fertilisation had contrasting effects on the three species of Miscanthus plants. These effects cascaded up to the second trophic level, R. maidis aphid pests, either through a modification of their weight or demographic parameters. The implications of these results were discussed in the context of agricultural sustainability and intensive production practices. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

  20. Population Dynamics of Empoasca fabae (Hemiptera: Cicadellidae) in Central Iowa Alfalfa Fields

    Science.gov (United States)

    Weiser Erlandson, L. A.; Obrycki, J. J.

    2015-01-01

    Adults and nymphs of Empoasca fabae Harris (Hemiptera: Cicadellidae) and adults of predatory species in the families Coccinellidae, Anthocoridae, Nabidae, Chrysopidae, and Hemerobiidae were sampled in Iowa alfalfa fields from June to September in 1999 and 2000. The relationship between each predatory taxa and E. fabae was examined using regression analysis. In 2000, all predators were found to be positively correlated with the presence of E. fabae during all periods sampled and most likely contributed to mortality. Orius insidiosus (Say) (Hemiptera: Anthoridae) was the most numerous insect predatory species; population numbers ranged from 0 to 1 and 0.1 to 3.7 adults per 0.25 m2 in 1999 and 2000, respectively. Partial life tables were constructed for E. fabae nymphs for two alfalfa-growing periods. Nymphs were grouped into three age intervals: first and second, third and fourth, and fifth instars. For the first alfalfa growing period examined, E. fabae nymphal mortality was 70% in 1999 and 49% in 2000. During the last growing period of each season (August–September), total nymphal mortality was relatively low (<25%). Adult E. fabae density ranged from 5.4 to 25.6 and 1.4–9.2 per 0.25 m2 in 1999 and 2000, respectively. E. fabae population peaks were similar for each age interval in all growing periods. This study provides further information on the population dynamics of E. fabae and its relationship with select predatory species in Iowa alfalfa fields. PMID:26320260

  1. Potential of plant growth regulator and chlormequat chloride on alfalfa seed components

    International Nuclear Information System (INIS)

    Chen, J. S.; Lin, H.; Han, W.

    2016-01-01

    The use of plant growth regulators (PGRs) has opened new prospects for increased seed production in grasses and legumes, but little information is available on the effects of PGRs combination with chlormequat chloride (CCC) on alfalfa (Medicago sativa L.) seed yield components. This study was conducted to evaluate the effects of applying chlormequat chloride in combination with three PGRs (Naphthylacetic acid (NAA), gibberellic acid 3 (GA), and brassinolide (BR)) on seed yield, aboveground biomass, plant height, lodging, yield components. CCC was applied annually at the stooling stage while three PGRs were applied twice each year at the stages of flower bud formation and peak flowering. Results provides evidence that: (i) each PGR consistently increased seed yields, and the numbers of seeds per stem compared to untreated plants; (ii) CCC treatment reduced plant height and lodging, but also significantly decreased seed yield and did not affect aboveground biomass. (iii) effectiveness of CCC application depends on climatic conditions, especially in North-east China. (iiii) the optimum combination of CCC with a PGR to increase alfalfa seed production was failed to identify. (iiiii) no interactions between PGRs and CCC on seed yield were observed and neither the PGRs nor the CCC. But alfalfa seed yield could be improved by combining a PGR such as NAA. Our Results suggest that these PGRs could be used in alfalfa breeding to increase seed yield while maintaining high seed quality. (author)

  2. Releases of a natural flightless strain of the ladybird beetle Adalia bipunctata reduce aphid-born honeydew beneath urban lime trees

    NARCIS (Netherlands)

    Lommen, S.T.E.; Holness, T.C.; Kuik, van A.J.; Jong, de P.W.; Brakefield, P.M.

    2013-01-01

    Aphids can cause major environmental problems in urban areas. One important problem is the annual outbreaks of lime aphid, Eucallipterus tiliae (L.) (Hemiptera: Aphididae), which spoil the surroundings of lime trees by depositing honeydew. To date no environmentally friendly method has been

  3. Tools for evaluating Lipolexis oregmae (Hymenoptera: Aphidiidae) in the field: Effects of host aphid and host plant on mummy location and color plus improved methods for obtaining adults

    International Nuclear Information System (INIS)

    Singh, R.; Hoy, M.A.

    2007-01-01

    Lipolexis oregmae Gahan was introduced into Florida in a classical biological control program directed against the brown citrus aphid, Toxoptera citricida (Kirkaldy), on citrus. Prior to evaluating distribution, host range, and potential nontarget effects of L. oregmae in Florida, we evaluated the role of other potential host aphids and host plants on mummy production and location. Under laboratory conditions, this parasitoid produced the most progeny on the target pest, the brown citrus aphid on citrus. This parasitoid, unlike the majority of aphidiids, did not produce mummies on any of the host plants tested when reared in black citrus aphid T. aurantii (Boyer de Fonscolombe) on grapefruit, spirea aphid Aphis spiraecola Patch on grapefruit and pittosporum, cowpea aphid A. craccivora Koch on grapefruit and cowpeas, or melon aphid A. gossypii Glover on grapefruit and cucumber. Thus, sampling for L. oregmae mummies of these host aphids and host plants must involve holding foliage in the laboratory until mummies are produced. This parasitoid requires high relative humidity to produce adults because no adults emerged when mummies were held in gelatin capsules, but high rates of emergence were observed when mummies were held on 1.5% agar plates. In addition, we compared the color of 6 aphid hosts and the color of mummies produced by L. oregmae when reared in them to determine if color of mummies could be used to identify L. oregmae . Mummy color varied between aphid hosts and tested host plants, and is not a useful tool for identifying L. oregmae for nontarget effects. (author) [es

  4. The Role of Proanthocyanidins Complex in Structure and Nutrition Interaction in Alfalfa Forage

    OpenAIRE

    Jonker, Arjan; Yu, Peiqiang

    2016-01-01

    Alfalfa (Medicago sativa L.) is one of the main forages grown in the world. Alfalfa is a winter hardy, drought tolerant, N-fixing legume with a good longevity, high yield, high nutrient levels, high digestibility, unique structural to non-structural components ratio, high dry matter intake, and high animal productivity per hectare. However, its main limitation is its excessively rapid initial rate of protein degradation in the rumen, which results in pasture bloat and inefficient use of prote...

  5. Nitrogen replacement value of alfalfa to corn and wheat under irrigated Mediterranean conditions

    OpenAIRE

    Ballesta, A.; Lloveras, J.

    2010-01-01

    In crop rotations that include alfalfa (Medicago sativa L.), agronomic and environmental concerns mean that it is important to determine the N fertilizer contribution of this legume for subsequent crops in order to help to increase the sustainability of cropping systems. To determine the N fertilizer replacement value (FRV) of a 2-yr alfalfa crop on subsequent crops of corn (Zea mays L.) followed by wheat (Triticum aestivum L.) under irrigated Mediterranean conditions, two 4-yr rotations (alf...

  6. [Natural nucleotide polymorphism of the Srlk gene that determines salt stress tolerance in alfalfa (Medicago sativa L)].

    Science.gov (United States)

    Vishnevskaia, M S; Pavlov, A V; Dziubenko, E A; Dziubenko, N I; Potokina, E K

    2014-04-01

    Based on legume genome syntheny, the nucleotide sequence of Srlk gene, key role of which in response to salt stress was demonstrated for the model species Medicago truncatula, was identified in the major forage and siderate crop alfalfa (Medicago sativa). In twelve alfalfa samples originating from regions with contrasting growing conditions, 19 SNPs were revealed in the Srlk gene. For two nonsynonymous SNPs, molecular markers were designed that could be further used to analyze the association between Srlk gene nucleotide polymorphism and the variability in salt stress tolerance among alfalfa cultivars.

  7. Alfalfa response to irrigation from limited water supplies

    Science.gov (United States)

    A five-year field study (2007-2011) of irrigated alfalfa production with a limited water supply was conducted in southwest Kansas with two years of above-average precipitation, one year of average precipitation, and two years of below-average precipitation. The irrigation treatments were designed to...

  8. Monolignol biosynthesis in microsomal preparations from lignifying stems of alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Guo, Dianjing; Chen, Fang; Dixon, Richard A

    2002-11-01

    Microsomal preparations from lignifying stems of alfalfa (Medicago sativa L.) contained coniferaldehyde 5-hydroxylase activity and immunodetectable caffeic acid 3-O-methyltransferase (COMT), and catalyzed the S-adenosyl L-methionine (SAM) dependent methylation of caffeic acid, caffeyl aldehyde and caffeyl alcohol. When supplied with NADPH and SAM, the microsomes converted caffeyl aldehyde to coniferaldehyde, 5-hydroxyconiferaldehyde, and traces of sinapaldehyde. Coniferaldehyde was a better precursor of sinapaldehyde than was 5-hydroxyconiferaldehyde. The alfalfa microsomes could not metabolize 4-coumaric acid, 4-coumaraldehyde, 4-coumaroyl CoA, or ferulic acid. No metabolism of monolignol precursors was observed in microsomal preparations from transgenic alfalfa down-regulated in COMT expression. In most microsomal preparations, the level of the metabolic conversions was independent of added recombinant COMT. Taken together, the data provide only limited support for the concept of metabolic channeling in the biosynthesis of S monolignols via coniferaldehyde.

  9. Flavonoids released naturally from alfalfa promote development of symbiotic glomus spores in vitro.

    Science.gov (United States)

    Tsai, S M; Phillips, D A

    1991-05-01

    Because flavonoids from legumes induce transcription of nodulation genes in symbiotic rhizobial bacteria, it is reasonable to test whether these compounds alter the development of vesicular-arbuscular mycorrhizal (VAM) fungi that infect those plants. Quercetin-3-O-galactoside, the dominant flavonoid released naturally from alfalfa (Medicago sativa L.) seeds, promoted spore germination of Glomus etunicatum and Glomus macrocarpum in vitro. Quercetin produced the maximum increases in spore germination, hyphal elongation, and hyphal branching in G. etunicatum at 1 to 2.5 muM concentrations. Two flavonoids exuded from alfalfa roots, 4',7-dihydroxyflavone and 4',7-dihydroxyflavanone, also enhanced spore germination of this fungal species. Formononetin, an isoflavone that is released from stressed alfalfa roots, inhibited germination of both Glomus species. These in vitro results suggest that plant flavonoids may facilitate or regulate the development of VAM symbioses and offer new hope for developing pure, plant-free cultures of VAM fungi.

  10. Effects of cold plasma treatment on alfalfa seed growth under simulated drought stress

    Science.gov (United States)

    Jinkui, FENG; Decheng, WANG; Changyong, SHAO; Lili, ZHANG; Xin, TANG

    2018-03-01

    The effect of different cold plasma treatments on the germination and seedling growth of alfalfa (Medicago sativa L.) seeds under simulated drought stress conditions was investigated. Polyethyleneglycol-6000 (PEG 6000)with the mass fraction of 0% (purified water), 5%, 10%, and 15% were applied to simulate the drought environment. The alfalfa seeds were treated with 15 different power levels ranged between 0-280 W for 15 s. The germination potential, germination rate, germination index, seedling root length, seedling height, and vigor index were investigated. Results indicated significant differences between treated with proper power and untreated alfalfa seeds. With the increase of treatment power, these indexes mentioned above almost presented bimodal curves. Under the different mass fractions of PEG 6000, results showed that the lower power led to increased germination, and the seedlings presented good adaptability to different drought conditions. Meanwhile, higher power levels resulted in a decreased germination rate. Seeds treated with 40 W resulted in higher germination potential, germination rate, seedling height, root length, and vigor index. Vigor indexes of the treated seeds under different PEG 6000 stresses increased by 38.68%, 43.91%, 74.34%, and 39.20% respectively compared to CK0-0, CK5-0, CK10-0, and CK15-0 (the control sample under 0%, 5%, 10%, and 15% PEG 6000). Therefore, 40 W was regarded as the best treatment in this research. Although the trend indexes of alfalfa seeds treated with the same power were statistically the same under different PEG 6000 stresses, the cold plasma treatment had a significant effect on the adaptability of alfalfa seeds in different drought environments. Thus, this kind of treatment is worth implementing to promote seed growth under drought situations.

  11. Contrasting Strategies of Alfalfa Stem Elongation in Response to Fall Dormancy in Early Growth Stage: The Tradeoff between Internode Length and Internode Number

    Science.gov (United States)

    Wang, Zongli; Sun, Qizhong

    2015-01-01

    Fall dormancy (FD) in alfalfa (Medicago sativa L.) can be described using 11 FD ratings, is widely used as an important indicator of stress resistance, productive performance and spring growth. However, the contrasting growth strategies in internode length and internode number in alfalfa cultivars with different FD rating are poorly understood. Here, a growth chamber study was conducted to investigate the effect of FD on plant height, aboveground biomass, internode length, and internode number in alfalfa individuals in the early growth stages. In order to simulate the alfalfa growth environment in the early stage, 11 alfalfa cultivars with FD ratings from one to 11 were chosen and seeded at the greenhouse, and then were transplanted into an artificial growth chamber. The experimental design was a randomized complete block in a split-plot arrangement with three replicates. Plant height, above-ground biomass, internode length, and internode number were measured in early growth stage in all individuals. Our findings showed that plant height and the aboveground biomass of alfalfa did not significantly differ among 11 different FD rated cultivars. Also, internode length and internode number positively affected plant height and the aboveground biomass of alfalfa individuals and the average internode length significantly increased with increasing FD rating. However, internode number tended to sharply decline when the FD rating increased. Moreover, there were no correlations, slightly negative correlations, and strongly negative correlations between internode length and internode number in alfalfa individuals among the three scales, including within-FD ratings, within-FD categories and inter-FD ratings, respectively. Therefore, our results highlighted that contrasting growth strategies in stem elongation were adopted by alfalfa with different FD ratings in the early growth stage. Alfalfa cultivars with a high FD rating have longer internodes, whereas more dormant alfalfa

  12. First report of race 2 of Colletotrichum trifolii causing anthracnose on alfalfa (Medicago sativa) in Wisconsin

    Science.gov (United States)

    Anthracnose of alfalfa (Medicago sativa), caused by Colletotrichum trifolii, is widespread in the United States. Three physiological races have been described. Race 1 is reported to be the dominant race that is present wherever alfalfa is grown, while race 2 was reported in a limited area in the Mid...

  13. Preliminary Study on Effect of Herbicides on Alfalfa Yield and Weed Community Characteristics in Yellow River Delta, China

    Directory of Open Access Journals (Sweden)

    WANG Guo-liang

    2016-05-01

    Full Text Available Alfalfa(Medicago sativa is one of important legume forages worldwide. However, weed is the main factor limiting alfalfa production. Biomass quality and yield and stability of dry matter production during cultivation are directly associated with the interference of weeds which compete with alfalfa for water, light and nutrients. The use of herbicides is a good alternative for weed control. In order to control weed in alfalfa field with suitable herbicide in Yellow River delta, the effect of four herbicides(imazethapyr, quizalofop-p-ethyl, haloxyfop-r-methyl and oxyfluorfen with different concentration on afalfal yield and weed community characteristics were studied. The results showed that both imazethapyr and haloxyfop-r-methyl treatments could increase alfalfa yield, and the best herbicide application concentration was imazethapyr with 2 000 mL·hm-2 and haloxyfop-r-methyl with 700 mL·hm-2, but oxyfluorfen treatment would limit alfalfa growth significantly. Weed species numbers in the treatments of imazethapyr, quizalofop-p-ethyl and oxyfluorfen decreased significantly. Digitariasanguinalis, Portulacaoleracea and Echinochloacrusgalli were more difficult to control from specie important value in all treatments. Species diversity index decreased with higher herbicide concentration in all treatments. From this study, herbicide imazethapyr with 2 000 mL·hm-2 application concentration was the best weed control method, and the second one was haloxyfop-r-methyl with 700 mL·hm-2 application concentration.

  14. Crystal Structures and Binding Dynamics of Odorant-Binding Protein 3 from two aphid species Megoura viciae and Nasonovia ribisnigri.

    Science.gov (United States)

    Northey, Tom; Venthur, Herbert; De Biasio, Filomena; Chauviac, Francois-Xavier; Cole, Ambrose; Ribeiro, Karlos Antonio Lisboa; Grossi, Gerarda; Falabella, Patrizia; Field, Linda M; Keep, Nicholas H; Zhou, Jing-Jiang

    2016-04-22

    Aphids use chemical cues to locate hosts and find mates. The vetch aphid Megoura viciae feeds exclusively on the Fabaceae, whereas the currant-lettuce aphid Nasonovia ribisnigri alternates hosts between the Grossulariaceae and Asteraceae. Both species use alarm pheromones to warn of dangers. For N. ribisnigri this pheromone is a single component (E)-β-farnesene but M. viciae uses a mixture of (E)-β-farnesene, (-)-α-pinene, β-pinene, and limonene. Odorant-binding proteins (OBP) are believed to capture and transport such semiochemicals to their receptors. Here, we report the first aphid OBP crystal structures and examine their molecular interactions with the alarm pheromone components. Our study reveals some unique structural features: 1) the lack of an internal ligand binding site; 2) a striking groove in the surface of the proteins as a putative binding site; 3) the N-terminus rather than the C-terminus occupies the site closing off the conventional OBP pocket. The results from fluorescent binding assays, molecular docking and dynamics demonstrate that OBP3 from M. viciae can bind to all four alarm pheromone components and the differential ligand binding between these very similar OBP3s from the two aphid species is determined mainly by the direct π-π interactions between ligands and the aromatic residues of OBP3s in the binding pocket.

  15. Relationship of red and photographic infrared spectral radiances to alfalfa biomass, forage water content, percentage canopy cover, and severity of drought stress

    Science.gov (United States)

    Tucker, C. J.; Elgin, J. H., Jr.; Mcmurtrey, J. E., III

    1979-01-01

    Red and photographic infrared spectral data were collected using a handheld radiometer for two cuttings of alfalfa. Significant linear and non-linear correlation coefficients were found between the spectral variables and plant height, biomass, forage water content, and estimated canopy cover for the earlier alfalfa cutting. The alfalfa of later cutting experienced a period of severe drought stress which limited growth. The spectral variables were found to be highly correlated with the estimated drought scores for this alfalfa cutting.

  16. Genetic relationships among alfalfa gemplasms resistant to common ...

    African Journals Online (AJOL)

    Jane

    2011-10-03

    Oct 3, 2011 ... ... and is the autotetraploid that is naturally outcrossing, and thus is susceptible to inbreeding depression. So, the great majority of alfalfa cultivars are synthetic populations that have been developed from successive generations of random mating of selected. *Corresponding author. E-mail: lxl@caas.net.cn.

  17. The helper component-proteinase of cowpea aphid-borne mosaic virus

    NARCIS (Netherlands)

    Mlotshwa, S.

    2000-01-01

    Cowpea aphid-borne mosaic potyvirus causes severe yield losses in cowpea, an important legume crop in semi-arid regions of Africa. We have elucidated the genomic sequence of the virus and subsequently focused our attention on the so-called helper component-proteinase (HC-Pro), a

  18. Concurrent synthesis and release of nod-gene-inducing flavonoids from alfalfa roots

    International Nuclear Information System (INIS)

    Maxwell, C.A.; Phillips, D.A.

    1990-01-01

    Flavonoid signals from alfalfa (Medicago sativa L.) induce transcription of nodulation (nod) genes in Rhizobium meliloti. Alfalfa roots release three major nod-gene inducers: 4',7-dihydroxyflavanone, 4',7-dihydroxyflavone, and 4,4'-dihydroxy-2'-methoxychalcone. The objective of the present study was to define temporal relationships between synthesis and exudation for those flavonoids. Requirements for concurrent flavonoid biosynthesis were assessed by treating roots of intact alfalfa seedlings with [U- 14 C]-L-phenylalanine in the presence or absence of the phenylalanine ammonia-lyase inhibitor L-2-aminoxy-3-phenylpropionic acid (AOPP). In the absence of AOPP, each of the three flavonoids in exudates contained 14 C. In the presence of AOPP, 14 C labeling and release of all the exuded nod-gene inducers were reduced significantly. AOPP inhibited labeling and release of the strongest nod-gene inducer, methoxychalcone, by more than 90%. The release process responsible for exudation of nod-gene inducers appears to be specific rather than a general phenomenon such as a sloughing off of cells during root growth

  19. APHiD: Hierarchical Task Placement to Enable a Tapered Fat Tree Topology for Lower Power and Cost in HPC Networks

    Energy Technology Data Exchange (ETDEWEB)

    Michelogiannakis, George; Ibrahim, Khaled Z.; Shalf, John; Wilke, Jeremiah J.; Knight, Samuel; Kenny, Joseph P.

    2017-05-14

    The power and procurement cost of bandwidth in system-wide networks has forced a steady drop in the byte/flop ratio. This trend of computation becoming faster relative to the network is expected to hold. In this paper, we explore how cost-oriented task placement enables reducing the cost of system-wide networks by enabling high performance even on tapered topologies where more bandwidth is provisioned at lower levels. We describe APHiD, an efficient hierarchical placement algorithm that uses new techniques to improve the quality of heuristic solutions and reduces the demand on high-level, expensive bandwidth in hierarchical topologies. We apply APHiD to a tapered fat-tree, demonstrating that APHiD maintains application scalability even for severely tapered network configurations. Using simulation, we show that for tapered networks APHiD improves performance by more than 50% over random placement and even 15% in some cases over costlier, state-of-the-art placement algorithms.

  20. Resistance source to cowpea aphid (Aphis craccivora Koch) in ...

    African Journals Online (AJOL)

    STORAGESEVER

    2008-07-18

    Jul 18, 2008 ... The present study evaluated the resistance of 7 varieties of the broad bean Vicia faba L. to cowpea aphid, Aphis craccivora Koch, 1854. These landraces from the region of Biskra (in the south of Algeria) were selected in an initial field trial and subjected to further testing in the greenhouse. Landrace V51.

  1. Elucidating the resistance response of irradiated banana cv. Lakatan to banana bunchy top virus (BBTV) infection transmitted by the banana aphid Pentalonia nigronervosa Coquerol

    International Nuclear Information System (INIS)

    Dela Cueva, F.M.; Sison, M.L.J.; Dinglasan, E.G.; Damasco, O.P.

    2014-01-01

    Development of banana bunchy top virus (BBTV)-resistant banana variety Lakatan through gamma-irradiation had been successfully done as part of integrated management strategies against the disease. Ten irradiated Lakatan lines exhibited resistance to BBTV. Resistance of these lines was evaluated based on symptomatology and host-virus relationship. Insect colony development on Lakatan banana irradiated lines was monitored by artificially inoculating viruliferous banana aphids, Pentalonia nigronervosa, and counting the resulting number of aphids per plant at weekly intervals. Resistance to virus multiplication of Lakatan irradiated lines was characterized by quantifying the virus titer through Enzyme-Linked Immunosorbent Assay (ELISA). Results showed that not all lines were suitable as hosts in establishing aphid population. The reaction of the mutant lines to the vector and the pathogen varied to some extent. Disease incidence in some cases was correlated with aphid preference. Disease incidence was significantly higher (50%) on lines that were preferred by aphids and lower (50%) in those that were not colonized. Some mutant lines with very low aphid colony count, however showed high BBTV incidence. Variability in the results could be affected by other factors such as the developmental stage of the plant and prevailing environmental conditions during the conduct of the experiment. Virus titer was also reduced on these mutant lines, thus reduced virus multiplication. Non-irradiated (control) Lakatan banana had comparably high population of aphids, high disease incidence, and high virus titer

  2. Association Mapping of Biomass Yield and Stem Composition in a Tetraploid Alfalfa Breeding Population

    Directory of Open Access Journals (Sweden)

    Xuehui Li

    2011-03-01

    Full Text Available Alfalfa ( L., an important forage crop that is also a potential biofuel crop, has advantages of high yield, high lignocellulose concentration in stems, and has low input costs. In this study, we investigated population structure and linkage disequilibrium (LD patterns in a tetraploid alfalfa breeding population using genome-wide simple sequence repeat (SSR markers and identified markers related to yield and cell wall composition by association mapping. No obvious population structure was found in our alfalfa breeding population, which could be due to the relatively narrow genetic base of the founders and/or due to two generations of random mating. We found significant LD ( 10% alleles across the 71 SSR markers, 15 showed strong association ( < 0.005 with yield in at least one of five environments, and most of the 15 alleles were identified in multiple environments. Only one allele showed strong association with acid detergent fiber (ADF and one allele with acid detergent lignin (ADL. Alleles associated with traits could be directly applied in a breeding program using marker-assisted selection. However, based on our estimated LD level, we would need about 1000 markers to explore the whole alfalfa genome for association between markers and traits.

  3. Boosting Alfalfa (Medicago sativa L. Production With Rhizobacteria From Various Plants in Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Ihsanullah Daur

    2018-04-01

    Full Text Available This study focused on rhizobacteria to promote sustainable crop production in arid regions of Saudi Arabia. The study isolated 17 tightly root-adhering rhizobacteria from various plants at Hada Al Sham in Saudi Arabia. All 17 rhizobacterial isolates were confirmed as plant growth promoting rhizobacteria by classical biochemical tests. Using 16S rDNA gene sequence analyses, the strains were identified as Bacillus, Acinetobacter and Enterobacter. Subsequently, the strains were assessed for their ability to improve the physiology, nutrient uptake, growth, and yield of alfalfa plants grown under desert agriculture conditions. The field trials were conducted in a randomized complete block design. Inoculation of alfalfa with any of these 17 strains improved the relative water content; chlorophyll a; chlorophyll b; carotenoid contents; nitrogen (N, phosphorus, and potassium contents; plant height; leaf-to-stem ratio; and fresh and dry weight. Acinetobacter pittii JD-14 was most effective to increase fresh and dry weight of alfalfa by 41 and 34%, respectively, when compared to non-inoculated control plants. Nevertheless, all strains enhanced crop traits when compared to controls plants, indicating that these desert rhizobacterial strains could be used to develop an eco-friendly biofertilizer for alfalfa and possibly other crop plants to enhance sustainable production in arid regions.

  4. Boosting Alfalfa (Medicago sativa L.) Production With Rhizobacteria From Various Plants in Saudi Arabia

    KAUST Repository

    Daur, Ihsanullah; Saad, Maged; Eida, Abdul Aziz; Ahmad, Shakeel; Shah, Zahid Hussain; Ihsan, Muhammad Z.; Muhammad, Yasir; Sohrab, Sayed S.; Hirt, Heribert

    2018-01-01

    This study focused on rhizobacteria to promote sustainable crop production in arid regions of Saudi Arabia. The study isolated 17 tightly root-adhering rhizobacteria from various plants at Hada Al Sham in Saudi Arabia. All 17 rhizobacterial isolates were confirmed as plant growth promoting rhizobacteria by classical biochemical tests. Using 16S rDNA gene sequence analyses, the strains were identified as Bacillus, Acinetobacter and Enterobacter. Subsequently, the strains were assessed for their ability to improve the physiology, nutrient uptake, growth, and yield of alfalfa plants grown under desert agriculture conditions. The field trials were conducted in a randomized complete block design. Inoculation of alfalfa with any of these 17 strains improved the relative water content; chlorophyll a; chlorophyll b; carotenoid contents; nitrogen (N), phosphorus, and potassium contents; plant height; leaf-to-stem ratio; and fresh and dry weight. Acinetobacter pittii JD-14 was most effective to increase fresh and dry weight of alfalfa by 41 and 34%, respectively, when compared to non-inoculated control plants. Nevertheless, all strains enhanced crop traits when compared to controls plants, indicating that these desert rhizobacterial strains could be used to develop an eco-friendly biofertilizer for alfalfa and possibly other crop plants to enhance sustainable production in arid regions.

  5. Boosting Alfalfa (Medicago sativa L.) Production With Rhizobacteria From Various Plants in Saudi Arabia.

    Science.gov (United States)

    Daur, Ihsanullah; Saad, Maged M; Eida, Abdul Aziz; Ahmad, Shakeel; Shah, Zahid Hussain; Ihsan, Muhammad Z; Muhammad, Yasir; Sohrab, Sayed S; Hirt, Heribert

    2018-01-01

    This study focused on rhizobacteria to promote sustainable crop production in arid regions of Saudi Arabia. The study isolated 17 tightly root-adhering rhizobacteria from various plants at Hada Al Sham in Saudi Arabia. All 17 rhizobacterial isolates were confirmed as plant growth promoting rhizobacteria by classical biochemical tests. Using 16S rDNA gene sequence analyses, the strains were identified as Bacillus, Acinetobacter and Enterobacter . Subsequently, the strains were assessed for their ability to improve the physiology, nutrient uptake, growth, and yield of alfalfa plants grown under desert agriculture conditions. The field trials were conducted in a randomized complete block design. Inoculation of alfalfa with any of these 17 strains improved the relative water content; chlorophyll a; chlorophyll b; carotenoid contents; nitrogen (N), phosphorus, and potassium contents; plant height; leaf-to-stem ratio; and fresh and dry weight. Acinetobacter pittii JD-14 was most effective to increase fresh and dry weight of alfalfa by 41 and 34%, respectively, when compared to non-inoculated control plants. Nevertheless, all strains enhanced crop traits when compared to controls plants, indicating that these desert rhizobacterial strains could be used to develop an eco-friendly biofertilizer for alfalfa and possibly other crop plants to enhance sustainable production in arid regions.

  6. Fiber length and pulping characteristics of switchgrass, alfalfa stems, hybrid poplar and willow biomasses.

    Science.gov (United States)

    Ai, Jun; Tschirner, Ulrike

    2010-01-01

    Switchgrass (Panicum virgatum), alfalfa stems (Medicago sativa), second year growth hybrid poplar (Populus) and willow (Salix spp.) were examined to determine fiber characteristics, pulping behavior and paper properties. Alfalfa stems and switchgrass both showed length weighted average fiber length (LWW) of 0.78 mm, a very narrow fiber length distribution and high fines content. Willow and hybrid poplar have lower fines content but a very low average fiber length (0.42 and 0.48 mm LWW). In addition, the four biomass species showed distinctly different chemical compositions. Switchgrass was defibered successfully using Soda and Soda Anthraquinone (AQ) pulping and demonstrated good paper properties. Both fast-growing wood species pulped well using the Kraft process, and showed acceptable tensile strength, but low tear strength. Alfalfa stems reacted very poorly to Soda and Soda AQ pulping but responded well to Kraft and Kraft AQ. Pulps with tensile and tear strength considerably higher than those found for commercial aspen pulps were observed for alfalfa. All four biomass species examined demonstrated low pulp yield. The highest yields were obtained with poplar and switchgrass (around 43%). Considering the short fibers and low yields, all four biomass types will likely only be used in paper manufacturing if they offer considerable economic advantage over traditional pulp wood.

  7. Boosting Alfalfa (Medicago sativa L.) Production With Rhizobacteria From Various Plants in Saudi Arabia

    KAUST Repository

    Daur, Ihsanullah

    2018-04-04

    This study focused on rhizobacteria to promote sustainable crop production in arid regions of Saudi Arabia. The study isolated 17 tightly root-adhering rhizobacteria from various plants at Hada Al Sham in Saudi Arabia. All 17 rhizobacterial isolates were confirmed as plant growth promoting rhizobacteria by classical biochemical tests. Using 16S rDNA gene sequence analyses, the strains were identified as Bacillus, Acinetobacter and Enterobacter. Subsequently, the strains were assessed for their ability to improve the physiology, nutrient uptake, growth, and yield of alfalfa plants grown under desert agriculture conditions. The field trials were conducted in a randomized complete block design. Inoculation of alfalfa with any of these 17 strains improved the relative water content; chlorophyll a; chlorophyll b; carotenoid contents; nitrogen (N), phosphorus, and potassium contents; plant height; leaf-to-stem ratio; and fresh and dry weight. Acinetobacter pittii JD-14 was most effective to increase fresh and dry weight of alfalfa by 41 and 34%, respectively, when compared to non-inoculated control plants. Nevertheless, all strains enhanced crop traits when compared to controls plants, indicating that these desert rhizobacterial strains could be used to develop an eco-friendly biofertilizer for alfalfa and possibly other crop plants to enhance sustainable production in arid regions.

  8. Toxicological responses in alfalfa ( Medicago sativa ) under joint ...

    African Journals Online (AJOL)

    Joint effects of Cd2+ and napropamide in seeds, roots or leaves of alfalfa were investigated under different treatments. It was shown that single stress of Cd2+ or napropamide decreased chlorophyll content after 30 days of treatment in different concentrations. The decrease in chlorophyll content became insignificant under ...

  9. Relationships among alfalfa resistance to Sclerotinia crown and ...

    African Journals Online (AJOL)

    Zilvinas

    2012-09-06

    Sep 6, 2012 ... MATERIALS AND METHODS. Experimental site and plant material. The experiments were carried out at the Institute of Agriculture, during the period of 2009 to 2011. The alfalfa material was subjected for investigation of resistance to S. trifoliorum, OA under laboratory and resistance to SCSR under field ...

  10. Neonicotinoid Binding, Toxicity and Expression of Nicotinic Acetylcholine Receptor Subunits in the Aphid Acyrthosiphon pisum

    Science.gov (United States)

    Taillebois, Emiliane; Beloula, Abdelhamid; Quinchard, Sophie; Jaubert-Possamai, Stéphanie; Daguin, Antoine; Servent, Denis; Tagu, Denis

    2014-01-01

    Neonicotinoid insecticides act on nicotinic acetylcholine receptor and are particularly effective against sucking pests. They are widely used in crops protection to fight against aphids, which cause severe damage. In the present study we evaluated the susceptibility of the pea aphid Acyrthosiphon pisum to the commonly used neonicotinoid insecticides imidacloprid (IMI), thiamethoxam (TMX) and clothianidin (CLT). Binding studies on aphid membrane preparations revealed the existence of high and low-affinity binding sites for [3H]-IMI (Kd of 0.16±0.04 nM and 41.7±5.9 nM) and for the nicotinic antagonist [125I]-α-bungarotoxin (Kd of 0.008±0.002 nM and 1.135±0.213 nM). Competitive binding experiments demonstrated that TMX displayed a higher affinity than IMI for [125I]-α-bungarotoxin binding sites while CLT affinity was similar for both [125I]-α-bungarotoxin and [3H]-IMI binding sites. Interestingly, toxicological studies revealed that at 48 h, IMI (LC50 = 0.038 µg/ml) and TMX (LC50 = 0.034 µg/ml) were more toxic than CLT (LC50 = 0.118 µg/ml). The effect of TMX could be associated to its metabolite CLT as demonstrated by HPLC/MS analysis. In addition, we found that aphid larvae treated either with IMI, TMX or CLT showed a strong variation of nAChR subunit expression. Using semi-quantitative PCR experiments, we detected for all insecticides an increase of Apisumα10 and Apisumβ1 expressions levels, whereas Apisumβ2 expression decreased. Moreover, some other receptor subunits seemed to be differently regulated according to the insecticide used. Finally, we also demonstrated that nAChR subunit expression differed during pea aphid development. Altogether these results highlight species specificity that should be taken into account in pest management strategies. PMID:24801634

  11. Weaned beef calves fed selenium-biofortified alfalfa hay have an enriched nasal microbiota compared with healthy controls.

    Science.gov (United States)

    Hall, Jean A; Isaiah, Anitha; Estill, Charles T; Pirelli, Gene J; Suchodolski, Jan S

    2017-01-01

    Selenium (Se) is an essential trace mineral important for immune function and overall health of cattle. The nasopharyngeal microbiota in cattle plays an important role in overall respiratory health, especially when stresses associated with weaning, transport, and adaptation to a feedlot affect the normal respiratory defenses. Recent evidence suggests that cattle diagnosed with bovine respiratory disease complex have significantly less bacterial diversity. The objective of this study was to determine whether feeding weaned beef calves Se-enriched alfalfa (Medicago sativa) hay for 9 weeks in a preconditioning program prior to entering the feedlot alters nasal microbiota. Recently weaned beef calves (n = 45) were blocked by sex and body weight, randomly assigned to 3 treatment groups with 3 pens of 5 calves per treatment group, and fed an alfalfa hay based diet for 9 weeks. Alfalfa hay was harvested from fields fertilized with sodium selenate at a rate of 0, 45.0 or 89.9 g Se/ha. Blood samples were collected biweekly and analyzed for whole-blood Se concentrations. Nasal swabs were collected during week 9 from one or two calves from each pen (total n = 16). Calculated Se intake from dietary sources was 3.0, 15.6, and 32.2 mg Se/head/day for calves consuming alfalfa hay with Se concentrations of 0.34 to 2.42 and 5.17 mg Se/kg dry matter, respectively. Whole-blood Se concentrations after 8 weeks of feeding Se-fertilized alfalfa hay were dependent upon Se-application rates (0, 45.0, or 89.9 g Se/ha) and were 155, 345, and 504 ng/mL (PLinear Microbial DNA was extracted from nasal swabs and amplified and sequenced. Alpha rarefaction curves comparing the species richness (observed OTUs) and overall diversity (Chao1, Observed OTU, and Shannon index) between calves fed selenium-biofortified alfalfa hay compared with control calves showed that Se-supplementation tended to be associated with an enriched nasal microbiota. ANOSIM of unweighted UniFrac distances showed that calves

  12. Weaned beef calves fed selenium-biofortified alfalfa hay have an enriched nasal microbiota compared with healthy controls

    Science.gov (United States)

    Hall, Jean A.; Isaiah, Anitha; Estill, Charles T.; Pirelli, Gene J.; Suchodolski, Jan S.

    2017-01-01

    Selenium (Se) is an essential trace mineral important for immune function and overall health of cattle. The nasopharyngeal microbiota in cattle plays an important role in overall respiratory health, especially when stresses associated with weaning, transport, and adaptation to a feedlot affect the normal respiratory defenses. Recent evidence suggests that cattle diagnosed with bovine respiratory disease complex have significantly less bacterial diversity. The objective of this study was to determine whether feeding weaned beef calves Se-enriched alfalfa (Medicago sativa) hay for 9 weeks in a preconditioning program prior to entering the feedlot alters nasal microbiota. Recently weaned beef calves (n = 45) were blocked by sex and body weight, randomly assigned to 3 treatment groups with 3 pens of 5 calves per treatment group, and fed an alfalfa hay based diet for 9 weeks. Alfalfa hay was harvested from fields fertilized with sodium selenate at a rate of 0, 45.0 or 89.9 g Se/ha. Blood samples were collected biweekly and analyzed for whole-blood Se concentrations. Nasal swabs were collected during week 9 from one or two calves from each pen (total n = 16). Calculated Se intake from dietary sources was 3.0, 15.6, and 32.2 mg Se/head/day for calves consuming alfalfa hay with Se concentrations of 0.34 to 2.42 and 5.17 mg Se/kg dry matter, respectively. Whole-blood Se concentrations after 8 weeks of feeding Se-fertilized alfalfa hay were dependent upon Se-application rates (0, 45.0, or 89.9 g Se/ha) and were 155, 345, and 504 ng/mL (PLinear calves fed selenium-biofortified alfalfa hay compared with control calves showed that Se-supplementation tended to be associated with an enriched nasal microbiota. ANOSIM of unweighted UniFrac distances showed that calves fed high Se-biofortified alfalfa hay clustered separately when compared with control calves in the PCoA plot (R = 0.216, P = 0.04). The bacterial orders Lactobacillales and Flavobacteriales were increased in healthy

  13. Female-induced increase of host-plant volatiles enhance specific attraction of aphid male Dysaphis plantaginea (Homoptera: Aphididae) to the sex pheromone

    NARCIS (Netherlands)

    Tol, van R.W.H.M.; Helsen, H.H.M.; Griepink, F.C.; Kogel, de W.J.

    2009-01-01

    All aphid species studied so far share the same sex pheromone components, nepetalactol and nepetalactone. Variation by different enantiomers and blends of the two components released by different aphid species are limited and can only partially explain species-specific attraction of males to

  14. Molecular evolution of aphids and their primary ( Buchnera sp.) and secondary endosymbionts: implications for the role of symbiosis in insect evolution.

    NARCIS (Netherlands)

    Sabater-Munoz, B.; Ham, van R.C.H.J.; Martinez-Torres, D.; Silva, F.J.; Latorre, A.; Moya, A.

    2001-01-01

    Aphids maintain an obligate, endosymbiotic association with Buchnera sp., a bacterium closely related to Escherichia coli. Bacteria are housed in specialized cells of organ-like structures called bacteriomes in the hemocoel of the aphid and are maternally transmitted. Phylogenetic studies have shown

  15. Chemical research of lipophilic fractions of sickle alfalfa herbs

    Directory of Open Access Journals (Sweden)

    S. V. Kovalev

    2013-06-01

    Full Text Available Lipophilic fraction (LF of known medicinal plants are still less studied, despite the fact that they have a unique group of biological active compounds (BAC. The main active substances of LF are chlorophylls, carotenoids, tocopherols, sterols, unsaturated fatty acids, phospholipids, and other bioactive substances that exhibit a wide spectrum of pharmacological action. In this regard, a comprehensive study of advanced plant of flora of Ukraine to increase the assortments of herbal remedies is an urgent problem. The aim of this work was to obtain and chemical research of lipophilic fractions of sickle alfalfa herbs. The alfalfa herb harvested throughout the growing season in Kharkov and Poltava regions in 2011-2012. Lipophilic fraction was obtained by extraction with chloroform in a Soxhlet apparatus. Detection of carotenoids and chlorophylls by thin layer chromatography (TLC on plates of "Silufol" in one-dimensional and two-dimensional variants, the solvent system were: hexane: acetone (6:2 - I way, hexane-acetone (6:4 - II way. Assay of the lipophilic fraction by three-dimensional fluorescence spectroscopy (3DF-spectroscopy was used for the analysis of mixtures containing fluorescent components. 3DF-spectres, that have the appearance of the surface, are characterized by a functions I = f (λexc, λem, recorded in the ultraviolet and visible ranges. Assay of the carotenoids and chlorophylls carried out by spectrophotometry. The reference solution was chloroform. Assay of fatty acids was performed by gas-liquid chromatography (GLC of methyl esters of fatty acids via chromatograph with flame ionization detector "Shimadzu GC-14B". 20.0 g crushed sickle alfalfa herbs were exhaustively extracted with chloroform in a Soxhlet apparatus for produce a lipophilic fractions. The chloroform extract was evaporated in order to remove the extractant. The percentage of lipophilic fraction in the herbs was 7.5%. Quantity of the carotenoids and chlorophylls

  16. Bacterial population dynamics during the ensiling of Medicago sativa (alfalfa) and subsequent exposure to air.

    Science.gov (United States)

    McGarvey, J A; Franco, R B; Palumbo, J D; Hnasko, R; Stanker, L; Mitloehner, F M

    2013-06-01

    To describe, at high resolution, the bacterial population dynamics and chemical transformations during the ensiling of alfalfa and subsequent exposure to air. Samples of alfalfa, ensiled alfalfa and silage exposed to air were collected and their bacterial population structures compared using 16S rRNA gene libraries containing approximately 1900 sequences each. Cultural and chemical analyses were also performed to complement the 16S gene sequence data. Sequence analysis revealed significant differences (P alfalfa-derived library contained mostly sequences associated with the Gammaproteobacteria (including the genera: Enterobacter, Erwinia and Pantoea); the ensiled material contained mostly sequences associated with the lactic acid bacteria (LAB) (including the genera: Lactobacillus, Pediococcus and Lactococcus). Exposure to air resulted in even greater percentages of LAB, especially among the genus Lactobacillus, and a significant drop in bacterial diversity. In-depth 16S rRNA gene sequence analysis revealed significant bacterial population structure changes during ensiling and again during exposure to air. This in-depth description of the bacterial population dynamics that occurred during ensiling and simulated feed out expands our knowledge of these processes. © 2013 The Society for Applied Microbiology No claim to US Government works.

  17. Evaluation of two supplements for the prevention of alfalfa bloat.

    Science.gov (United States)

    Hall, J W; Walker, I; Majak, W

    1994-11-01

    Poloxalene and a mineral mixture feed supplement patented for the treatment of emphysema, polyarthritis, and other pectin related diseases were tested in two trials for their ability to prevent bloat in cattle fed fresh alfalfa. Each trial had a crossover design using three Jersey steers with rumen fistulas per group. Each trial period continued until the total number of cases of bloat reached > or = 24. Treatments were given at 0800 each day. The mineral mixture was given at 100 g/d and 190 mg/kg body weight per day in the first and second trials, respectively. Poloxalene, which was tested only in the second trial, was given at 23 mg/kg body weight per day. Each group of steers was then fed 200 kg of freshly harvested alfalfa in the vegetative to early bloom stages of growth at 0830. In the first trial, only 69% as many cases of bloat occurred on the mineral mixture as on the control treatment, but no significant difference was detected in the second trial. The potency of the alfalfa may have been higher in the second trial, when forage dry matter was lower, magnesium and soluble nitrogen were higher, and bloat occasionally occurred twice a day. Bloat did not occur when the steers were treated with poloxalene. In these trials, poloxalene was completely effective in preventing bloat, but the mineral mixture was only partially so.

  18. Effect of absorbed dose and storage length on electron paramagnetic resonance (EPR) signal strength in irradiated alfalfa seeds

    International Nuclear Information System (INIS)

    Li Naining

    2006-01-01

    A kind of alfalfa seeds was irradiated by 1, 2, 3, 4 and 5 kGy at a dose rate of 6.288 kGy·h -1 in a self-shielded irradiator of 137 Cs gamma rays. The EPR spectra, which were measured subsequently between 0.3401 and 0.3501 T, showed that there was a direct proportional relationship between the EPR signal strength of free radicals produced by gamma irradiation in the alfalfa seeds and absorbed dose. The first derivative EPR spectra of the alfalfa seeds were very clear and easy to identify. However, the EPR signal strength of the peak-to-peak amplitude decreased rapidly and most of them decayed beyond 50% within 3 days after the seeds were irradiated. It tended to stabilize after half a month since the seeds were irradiated. the differences of the EPR signal strength between the irradiated and unirradiated alfalfa seeds still remained. All seeds were stored at ambient temperature for more than 3 months. Therefore, using EPR spectrometry technique to measure free radicals in alfalfa seeds as a means to determine whether the seeds have been irradiated or not is feasible, relatively fast and simple. (authors)

  19. Transgenic expression of a functional fragment of harpin protein Hpa1 in wheat induces the phloem-based defence against English grain aphid

    Science.gov (United States)

    Fu, Maoqiang; Xu, Manyu; Zhang, Chunling

    2014-01-01

    The harpin protein Hpa1 has multiple beneficial effects in plants, promoting plant growth and development, increasing crop yield, and inducing resistance to pathogens and insect pests. For these effects, the 10–40 residue fragment (Hpa110–42) isolated from the Hpa1 sequence is 1.3- to 7.5-fold more effective than the full-length protein. Here it is reported that the expression of Hpa110–42 under the direction of an insect-induced promoter induces the phloem-based defence to English grain aphid, a dominant species of wheat aphids. The expression of Hpa110–42 was found to compromise the colonization preference of aphids on the plant and further inhibit aphid reproduction in leaf colonies. In Hpa110–42-expressing wheat lines, moreover, aphid feeding from the phloem was repressed in correlation with the phloem-based defence. This defensive mechanism was shown as enhanced expression of wheat genes encoding phloem lectin proteins (PP2-A1 and PP2-A2) and β-1,3-glucan synthase-like enzymes (GSL2, GSL10, and GSL12). Both PP2-A and β-1,3-glucan formed high molecular mass polymers to block phloem sieve plate pores and therefore impede aphid feeding from the phloem. However, the phloem-based defence was impaired by treating plants with ethylene signalling inhibitors, suggesting the requirement for the ethylene signalling pathway. In addition, if Hpa110–42-expressing plants were subjected to attack by a small number of aphids, they newly acquired agriculturally beneficial characters, such as enhanced vegetative growth and increased tiller numbers and grain output values. These results suggest that the defensive and developmental roles of Hpa110–42 can be integrated into the germplasm of this agriculturally significant crop. PMID:24676030

  20. Plant-derived differences in the composition of aphid honeydew and their effects on colonies of aphid-tending ants

    Science.gov (United States)

    Pringle, Elizabeth G; Novo, Alexandria; Ableson, Ian; Barbehenn, Raymond V; Vannette, Rachel L

    2014-01-01

    In plant–ant–hemipteran interactions, ants visit plants to consume the honeydew produced by phloem-feeding hemipterans. If genetically based differences in plant phloem chemistry change the chemical composition of hemipteran honeydew, then the plant's genetic constitution could have indirect effects on ants via the hemipterans. If such effects change ant behavior, they could feed back to affect the plant itself. We compared the chemical composition of honeydews produced by Aphis nerii aphid clones on two milkweed congeners, Asclepias curassavica and Asclepias incarnata, and we measured the responses of experimental Linepithema humile ant colonies to these honeydews. The compositions of secondary metabolites, sugars, and amino acids differed significantly in the honeydews from the two plant species. Ant colonies feeding on honeydew derived from A. incarnata recruited in higher numbers to artificial diet, maintained higher queen and worker dry weight, and sustained marginally more workers than ants feeding on honeydew derived from A. curassavica. Ants feeding on honeydew from A. incarnata were also more exploratory in behavioral assays than ants feeding from A. curassavica. Despite performing better when feeding on the A. incarnata honeydew, ant workers marginally preferred honeydew from A. curassavica to honeydew from A. incarnata when given a choice. Our results demonstrate that plant congeners can exert strong indirect effects on ant colonies by means of plant-species-specific differences in aphid honeydew chemistry. Moreover, these effects changed ant behavior and thus could feed back to affect plant performance in the field. PMID:25505534

  1. Interspecific Associations between Cycloneda sanguinea and Two Aphid Species (Aphis gossypii and Hyadaphis foeniculi) in Sole-Crop and Fennel-Cotton Intercropping Systems.

    Science.gov (United States)

    Fernandes, Francisco S; Ramalho, Francisco S; Malaquias, José B; Godoy, Wesley A C; Santos, Bárbara Davis B

    2015-01-01

    Aphids cause significant damage to crop plants. Studies regarding predator-prey relationships in fennel (Foeniculum vulgare Mill.) and cotton (Gossypium hirsutum L.) crops are important for understanding essential ecological interactions in the context of intercropping and for establishing pest management programs for aphids. This study evaluated the association among Hyadaphis foeniculi (Passerini) (Hemiptera: Aphididae), Aphis gossypii Glover (Hemiptera: Aphididae) and Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae) in cotton with coloured fibres, fennel and cotton intercropped with fennel. Association analysis was used to investigate whether the presence or absence of prey and predator species can indicate possible interactions between aphids and ladybugs. Significant associations among both apterous and alate H. foeniculi and C. sanguinea were observed in both the fennel and fennel-cotton intercropping systems. The similarity analysis showed that the presence of aphids and ladybugs in the same system is significantly dependent on the type of crop. A substantial amount of evidence indicates that the presence of the ladybug C. sanguinea, is associated with apterous or alate A. gossypii and H. foeniculi in fennel-cotton intercropping system. We recommend that future research vising integrated aphid management taking into account these associations for take decisions.

  2. Evaluation of the Susceptibility of the Pea Aphid, Acyrthosiphon pisum, to a Selection of Novel Biorational Insecticides using an Artificial Diet

    Science.gov (United States)

    Sadeghi, Amin; Van Damme, Els J.M.; Smagghe, Guy

    2009-01-01

    An improved technique was developed to assay the toxicity of insecticides against aphids using an artificial diet. The susceptibility of the pea aphid Acyrthosiphon pisum (Harris) (Hemiptera: Aphidoidea) was determined for a selection of novel biorational insecticides, each representing a novel mode of action. Flonicamid, a novel systemic insecticide with selective activity as feeding blocker against sucking insects, showed high toxicity against first-instar A. pisum nymphs with an LC50 of 20.4 μg/ml after 24 h, and of 0.24 µg/ml after 72 h. The toxicity was compared with another feeding blocker, pymetrozine, and the neonicotinoid, imidacloprid. In addition, four insect growth regulators were tested. The chitin synthesis inhibitor flufenoxuron, the juvenile hormone analogue pyriproxyfen, and the azadirachtin compound Neem Azal-T/S showed strong effects and reduced the aphid population by 50% after 3 days of treatment at a concentration of 7–9 µg/ml. The ecdysone agonist tested, halofenozide, was less potent. In conclusion, the improved aphid feeding apparatus can be useful as a miniature screening device for insecticides against different aphid pests. The present study demonstrated rapid and strong toxicity of flonicamid, and other biorational insecticides towards A. pisum. PMID:20053120

  3. Transgenic plants expressing the coat protein gene of cowpea aphid ...

    African Journals Online (AJOL)

    Cowpea aphid-borne mosaic virus (CABMV) is a potyvirus that infects cowpea causing significant yield reduction. However, there is no durable natural resistance to the virus within the crop and genetic engineering for virus resistance was not possible because of a lack of an efficient, reliable and reproducible cowpea ...

  4. Phenotypic plasticity in the response of aphids to host plant quality

    Czech Academy of Sciences Publication Activity Database

    Thieme, T.; Truberg, B.; Dixon, Anthony F. G.

    2014-01-01

    Roč. 4, č. 2 (2014), s. 92-96 ISSN 1805-0174 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0073 Institutional support: RVO:67179843 Keywords : lupin * alkaloids * aphids * Macrosiphum albifrons * biological performance Subject RIV: EH - Ecology, Behaviour

  5. Transgene silencing of sucrose synthase in alfalfa (Medicago sativa L.) stem vascular tissue suggests a role for invertase in cell wall cellulose synthesis

    Science.gov (United States)

    Alfalfa (Medicago sativa L.) plants were transformed with two constructs: (1) a truncated phosphoenolpyruvate carboxylase promoter isolated from alfalfa nodules (PEPC-4) fused to GUS; and (2) PEPC-4 fused with sucrose synthase (SUS) isolated from alfalfa nodules. Histochemical staining for GUS in st...

  6. Interactions among the predatory midge Aphidoletes aphidimyza (Diptera: Cecidomyiidae), the fungal pathogen Metarhizium brunneum (Ascomycota: Hypocreales), and maize-infesting aphids in greenhouse mesocosms

    DEFF Research Database (Denmark)

    Campos de Azevedo, Ana Gorete; Steinwender, Bernhardt Michael; Eilenberg, Jørgen

    2017-01-01

    , the interaction between these two biological control organisms and how it may affect the biological control of aphids awaits further investigation. As part of the EU-supported project INBIOSOIL, this study was conducted in greenhouse conditions to assess the possible effects of combining both biological control...... by treatment. Aphidoletes aphidimyza applied alone suppressed the aphid population more effectively than M. brunneum applied alone. Additionally, the aphid population was most suppressed when both agents were combined, though the suppression was less than additive....

  7. Interactions among the Predatory Midge Aphidoletes aphidimyza (Diptera: Cecidomyiidae, the Fungal Pathogen Metarhizium brunneum (Ascomycota: Hypocreales, and Maize-Infesting Aphids in Greenhouse Mesocosms

    Directory of Open Access Journals (Sweden)

    Ana Gorete Campos de Azevedo

    2017-04-01

    Full Text Available The generalist entomopathogenic fungus, Metarhizium brunneum, has proved to have great potential as a versatile biological pest control agent. The gall midge Aphidoletes aphidimyza is a specialist predator that occurs naturally in Europe and has been successfully used for aphid suppression. However, the interaction between these two biological control organisms and how it may affect the biological control of aphids awaits further investigation. As part of the EU-supported project INBIOSOIL, this study was conducted in greenhouse conditions to assess the possible effects of combining both biological control agents. In a randomized complete block design, sweet corn (Zea mays var. saccharata plants were grown in large pots filled with natural soil or natural soil inoculated with M. brunneum. At the third leaf stage, before being individually caged, plants were infested with Rhopalosiphum padi and A. aphidimyza pupae were introduced in the soil. Aphidoletes aphidimyza midge emergence, number of living midges and number of aphids were recorded daily. The presence of conidia in the soil and on leaves was assessed during the experiment. At the conclusion of the experiment, the number of live aphids and their developmental stage, consumed aphids, and A. aphidimyza eggs was assessed under stereomicroscope. This study’s findings showed that the presence of M. brunneum did not affect A. aphidimyza midge emergence. However, longevity was significantly affected. As the study progressed, significantly fewer predatory midges were found in cages treated with M. brunneum compared to untreated cages. Furthermore, by the end of the study, the number of predatory midges found in the Metarhizium-treated cages was four times lower than in the untreated cages. Both daily and final count of aphids were significantly affected by treatment. Aphidoletes aphidimyza applied alone suppressed the aphid population more effectively than M. brunneum applied alone. Additionally

  8. Scaling up population dynamic processes in a ladybird–aphid

    Czech Academy of Sciences Publication Activity Database

    Houdková, Kateřina; Kindlmann, Pavel

    2006-01-01

    Roč. 48, - (2006), s. 323-332 ISSN 1438-3896 R&D Projects: GA ČR(CZ) GEDIV/06/E013; GA MŠk(CZ) LC06073; GA AV ČR(CZ) IAA6087301; GA ČR(CZ) GD206/03/H034 Keywords : Aphids * Egg window * Ladybirds * Metapopulation * Model * Population dynamics Subject RIV: EH - Ecology, Behaviour Impact factor: 1.534, year: 2006

  9. Distribution of hydrogen-metabolizing bacteria in alfalfa field soil

    International Nuclear Information System (INIS)

    Cunningham, S.D.; Kapulnik, Y.; Phillips, D.A.

    1986-01-01

    H 2 evolved by alfalfa root nodules during the process of N 2 fixation may be an important factor influencing the distribution of soil bacteria. To test this hypothesis under field conditions, over 700 bacterial isolates were obtained from fallow soil or from the 3-mm layer of soil surrounding alfalfa (Medicago sativa L.) root nodules, alfalfa roots, or bindweed (Convolvulus arvensis L.) roots. Bacteria were isolated under either aerobic or microaerophilic conditions and were tested for their capacity to metabolize H 2 . Isolates showing net H 2 uptake and 3 H 2 incorporation activity under laboratory conditions were assigned a Hup + phenotype, whereas organisms with significant H 2 output capacity were designated as a Hout + phenotype. Under aerobic isolation conditions two Hup + isolates were obtained, whereas under microaerophilic conditions five Hup + and two Hout + isolates were found. The nine isolates differed on the basis of 24 standard bacteriological characteristics or fatty acid composition. Five of the nine organisms were isolated from soil around root nodules, whereas the other four were found distributed among the other three soil environments. On the basis of the microaerophilic isolations, 4.8% of the total procaryotic isolates from soil around root nodules were capable of oxidizing H 2 , and 1.2% could produce H 2 . Two of the Hup + isolates were identified as Rhizobium meliloti by root nodulation tests, but the fact that none of the isolates reduced C 2 H 2 under the assay conditions suggested that the H 2 metabolism traits were associated with various hydrogenase systems rather than with nitrogenase activity

  10. Extending ALFALFA in the Direction of the Pisces-Perseus Supercluster with the Arecibo L-Band Wide Receiver

    Science.gov (United States)

    O'Donoghue, Aileen A.; Haynes, Martha P.; Koopmann, Rebecca A.; Jones, Michael G.; Hallenbeck, Gregory L.; Giovanelli, Riccardo; Hoffman, Lyle; Craig, David W.; Undergraduate ALFALFA Team

    2017-01-01

    We have completed three “Harvesting ALFALFA” Arecibo observing programs in the direction of the Pisces-Perseus Supercluster (PPS) since ALFALFA observations were finished in 2012. The first was to perform follow-up observations on high signal-to-noise (S/N > 6.5) ALFALFA detections needing confirmation and low S/N sources lacking optical counterparts. A few more high S/N objects were observed in the second program along with targets visually selected from the Sloan Digital Sky Survey (SDSS). The third program included low S/N ALFALFA sources having optical counterparts with redshifts that were unknown or differed from the ALFALFA observations. It also included more galaxies selected from SDSS by eye and by Structured Query Language (SQL) searches with parameters intended to select galaxies at the distance of the PPS (~6,000 km/s). We used pointed basic Total-Power Position-Switched Observations in the 1340 - 1430 MHz ALFALFA frequency range. For sources of known redshift, we used the Wideband Arecibo Pulsar Processors (WAPP’s) , while for sources of unknown redshift we utilized a hybrid/dual bandwidth Doppler tracking mode using the Arecibo Interim 50-MHz Correlator with 9-level sampling.Results confirmed that a few high S/N ALFALFA sources are spurious as expected from the work of Saintonge (2007), low S/N ALFALA sources lacking an optical counterpart are all likely to be spurious, but low S/N sources with optical counterparts are generally reliable. Of the optically selected sources, about 80% were detected and tended to be near the distance of the PPS.This work has been supported by NSF grant AST-1211005.

  11. Use of electrical penetration graphs (EPG) and quantitative PCR to evaluate the relationship between feeding behaviour and Pandora neoaphidis infection levels in green peach aphid, Myzus persicae.

    Science.gov (United States)

    Chen, Chun; Ye, Sudan; Hu, Huajun; Xue, Chengmei; Yu, Xiaoping

    2018-01-01

    A real-time qPCR method was developed, validated, and used to quantity the fungal pathogen, P. neoaphidis, within aphids at different times during infection; colonization rate fitted the Gompertz model well (R 2  = 0.9356). Feeding behaviour of P. neoaphidis-infected and uninfected M. persicae were investigated, for the first time, using DC-electrical penetration graphs (DC-EPG) that characterized the waveforms made during different aphid stylet probing periods corresponding to epidermis penetration, salivation and ingestion. In the 6 h following the 12-h incubation period (to achieve infection), there were significant differences in the number of events of Np (non-probing) and C (stylet pathway) between infected and uninfected aphids. However, the difference between total duration of Np and C were not significantly different between infected and uninfected aphids. There were no significant differences in the number of events or total duration of E1 (phloem salivation) or E2 (phloem ingestion) between infected and uninfected aphids. There were significant differences in mean number of events and total duration of the pd waveform (intracellular punctures) in infected and uninfected aphids. In the 16 h prior to death, the same differences in behaviour were observed but they were even more obvious. Furthermore, the total duration time of E2 was significantly greater in uninfected aphids than infected aphids, a change that had not been observed in the first 6 h observation period. In conclusion, qPCR quantification demonstrated 'molecular' colonization levels throughout infection, and EPG data analysis during the two periods (during early infection and then during late infection just prior to death) demonstrated the actual physical effects of fungal infection on feeding behaviour of M. persicae; this has the potential to decrease the aphid's capacity of transmission and dispersal. These studies increase our understanding of the interaction between P

  12. Method To immobilize the aphid-pathogenic fungus erynia neoaphidis in an alginate matrix for biocontrol

    Science.gov (United States)

    Shah; Aebi; Tuor

    1998-11-01

    Erynia neoaphidis is an important fungal pathogen of aphid pests worldwide. There have been few reported attempts to formulate this natural agent for use in biocontrol. In the current study, factors involved in the immobilization of E. neoaphidis hyphae in an alginate matrix were investigated. Hyphae of two isolates cultured in liquid medium were 220 to 620 &mgr;m in length and 7 to 19 &mgr;m in diameter with a 74 to 83% cytoplasmic content. The optimal concentration of low-viscosity sodium alginate for production of conidia from entrapped hyphae was 1.5% (wt/vol), and 0.1 and 0.25 M calcium chloride were equally suitable for use as the gelling solution. Alginate beads were rinsed with 10% sucrose after gelling. However, beads should not be left for longer than 40 min in 0.1 M calcium chloride or 10% sucrose to prevent a 10% loss in conidial production. A 40% (vol/vol) concentration of fungal biomass produced significantly more conidia than either 20% or the standard concentration of 10%. This effect persisted even after beads were dried overnight in a laminar flow hood and stored at 4 degreesC for 4 days. Conidia from freshly produced alginate beads caused 27 to 32% infection in Pea aphids as determined by standardized laboratory bioassays. This finding was not significantly different from infections in aphids inoculated with fresh mycelial mats or plugs from Petri dish cultures. In conclusion, algination appears to be a promising technique for utilizing E. neoaphidis in the biocontrol of aphid pests.

  13. Rice-straw mulch reduces the green peach aphid, Myzus persicae (Hemiptera: Aphididae) populations on kale, Brassica oleracea var. acephala (Brassicaceae) plants.

    Science.gov (United States)

    Silva-Filho, Reinildes; Santos, Ricardo Henrique Silva; Tavares, Wagner de Souza; Leite, Germano Leão Demolin; Wilcken, Carlos Frederico; Serrão, José Eduardo; Zanuncio, José Cola

    2014-01-01

    Organic mulches, like peel and rice-straw, besides other materials affect the UV and temperature, which cause a reduction in the aphid arrival. The aim was to evaluate the effect of covering the soil with straw on the populations of the green peach aphid, Myzus persicae on the kale, Brassica oleracea var. acephala plants. The first experiment evaluated the direct effect of the rice-straw mulch and the second its indirect effect on aphid immigration, testing the plant characteristics that could lead to the landing preference of this insect. The third experiment evaluated the direct effect of the mulch on the aphid population. In the second and third experiments, four plants, each in a 14 L polyethylene pot with holes at the bottom, were used in areas with and without soil mulching. These pots were changed between areas, after seven days, to evaluate the effects of this change on the arrival of the winged aphids to the plants. Each plant was covered with anti-aphid gauze and inoculated with one winged M. persicae. Winged and apterous adults of this insect were counted per plant after 15 days. The temperature increased in the mulched plots to a maximum of 21-36°C and to 18-32°C in the plots with or without soil covering, respectively. Plant growth reduced the numbers of the winged aphids landing before and after they were moved to the bare soil plots. The nutrient content was similar in plants in both the mulched and no mulched plots. The population growth of M. persicae was higher in the control than in the mulched plots. This was partially due to temperatures close to 30°C in these plots and changes in the plant physiology. The soil mulching with rice-straw decreased the M. persicae landing, increased the plot temperatures and improved the vegetative growth of the kale plants.

  14. Rice-straw mulch reduces the green peach aphid, Myzus persicae (Hemiptera: Aphididae populations on kale, Brassica oleracea var. acephala (Brassicaceae plants.

    Directory of Open Access Journals (Sweden)

    Reinildes Silva-Filho

    Full Text Available Organic mulches, like peel and rice-straw, besides other materials affect the UV and temperature, which cause a reduction in the aphid arrival. The aim was to evaluate the effect of covering the soil with straw on the populations of the green peach aphid, Myzus persicae on the kale, Brassica oleracea var. acephala plants. The first experiment evaluated the direct effect of the rice-straw mulch and the second its indirect effect on aphid immigration, testing the plant characteristics that could lead to the landing preference of this insect. The third experiment evaluated the direct effect of the mulch on the aphid population. In the second and third experiments, four plants, each in a 14 L polyethylene pot with holes at the bottom, were used in areas with and without soil mulching. These pots were changed between areas, after seven days, to evaluate the effects of this change on the arrival of the winged aphids to the plants. Each plant was covered with anti-aphid gauze and inoculated with one winged M. persicae. Winged and apterous adults of this insect were counted per plant after 15 days. The temperature increased in the mulched plots to a maximum of 21-36°C and to 18-32°C in the plots with or without soil covering, respectively. Plant growth reduced the numbers of the winged aphids landing before and after they were moved to the bare soil plots. The nutrient content was similar in plants in both the mulched and no mulched plots. The population growth of M. persicae was higher in the control than in the mulched plots. This was partially due to temperatures close to 30°C in these plots and changes in the plant physiology. The soil mulching with rice-straw decreased the M. persicae landing, increased the plot temperatures and improved the vegetative growth of the kale plants.

  15. Development of simple sequence repeat markers and diversity analysis in alfalfa (Medicago sativa L.).

    Science.gov (United States)

    Wang, Zan; Yan, Hongwei; Fu, Xinnian; Li, Xuehui; Gao, Hongwen

    2013-04-01

    Efficient and robust molecular markers are essential for molecular breeding in plant. Compared to dominant and bi-allelic markers, multiple alleles of simple sequence repeat (SSR) markers are particularly informative and superior in genetic linkage map and QTL mapping in autotetraploid species like alfalfa. The objective of this study was to enrich SSR markers directly from alfalfa expressed sequence tags (ESTs). A total of 12,371 alfalfa ESTs were retrieved from the National Center for Biotechnology Information. Total 774 SSR-containing ESTs were identified from 716 ESTs. On average, one SSR was found per 7.7 kb of EST sequences. Tri-nucleotide repeats (48.8 %) was the most abundant motif type, followed by di-(26.1 %), tetra-(11.5 %), penta-(9.7 %), and hexanucleotide (3.9 %). One hundred EST-SSR primer pairs were successfully designed and 29 exhibited polymorphism among 28 alfalfa accessions. The allele number per marker ranged from two to 21 with an average of 6.8. The PIC values ranged from 0.195 to 0.896 with an average of 0.608, indicating a high level of polymorphism of the EST-SSR markers. Based on the 29 EST-SSR markers, assessment of genetic diversity was conducted and found that Medicago sativa ssp. sativa was clearly different from the other subspecies. The high transferability of those EST-SSR markers was also found for relative species.

  16. No choice but to find resistance to soybean aphid biotype 4

    Science.gov (United States)

    Host plant resistance in soybean [Glycine max (L.) Merr] utilizes its natural defenses to limit soybean aphid (Aphis glycines Matsamura, SBA) injury, reducing insecticide reliance. Specific genes called Rag or Resistance to Aphis glycines are unfavorable to SBA and may suppress their development and...

  17. Two-year oscillation cycle in abundance of soybean aphid in Indiana

    Czech Academy of Sciences Publication Activity Database

    Rhainds, M.; Yoo, H. J. S.; Kindlmann, Pavel; Voegtlin, D.; Castillo, D.; Rutledge, C.; Sadof, C.; Yaninek, S.; O'Neil, R. J.

    2010-01-01

    Roč. 12, č. 3 (2010), s. 251-257 ISSN 1461-9555 Institutional research plan: CEZ:AV0Z60870520 Keywords : Aphididae * Aphis glycines * autumn migration * Hemiptera * heteroecy * Rhamnus * seesaw effect * soybean aphid Subject RIV: EH - Ecology, Behaviour Impact factor: 1.484, year: 2010

  18. Effect of Non Thermal Plasma on Alfalfa (Medicago sativa L.) Forage Production

    International Nuclear Information System (INIS)

    Abd El-Daem, G.A.N.A.; El-Aragi, G.M.; Tarrad, M.M.; Zayed, E.M.

    2013-01-01

    Field experiments were conducted at Atomic Energy Authority (AEA) Farm, at Inshas, Egypt during 2011–2012 on alfalfa. The aim of this investigation to caused mutation in alfalfa to obtain new variation. Seeds of the alfalfa were subjected to six doses of non-thermal plasma pulse. The plasma (consisting of ozone, UV and visible light) was injected into the seed samples for different durations or number of pulses. The doses used treatments were 2, 4, 6, 8, and 10 pulses (P) and non-treated control. The results showed difference seeds in both level field performances from cut 1st to cut 10th in the forage production. The results showed differences between the Control and treatment (number of pulses (P)) in each of all cuts for the productivity. The results showed the impact of plant height, Number of leaves/plant and number of branches/leaf and stem diameter as well as fresh weight of plant, fresh/weight (t/fed), dry yield (t/fed) in some cuts for Pulses 2, 4 and 10, and the ten pulses were the best for the majority of the qualities and cuts.

  19. De novo characterization of fall dormant and nondormant alfalfa (Medicago sativa L.) leaf transcriptome and identification of candidate genes related to fall dormancy.

    Science.gov (United States)

    Zhang, Senhao; Shi, Yinghua; Cheng, Ningning; Du, Hongqi; Fan, Wenna; Wang, Chengzhang

    2015-01-01

    Alfalfa (Medicago sativa L.) is one of the most widely cultivated perennial forage legumes worldwide. Fall dormancy is an adaptive character related to the biomass production and winter survival in alfalfa. The physiological, biochemical and molecular mechanisms causing fall dormancy and the related genes have not been well studied. In this study, we sequenced two standard varieties of alfalfa (dormant and non-dormant) at two time points and generated approximately 160 million high quality paired-end sequence reads using sequencing by synthesis (SBS) technology. The de novo transcriptome assembly generated a set of 192,875 transcripts with an average length of 856 bp representing about 165.1 Mb of the alfalfa leaf transcriptome. After assembly, 111,062 (57.6%) transcripts were annotated against the NCBI non-redundant database. A total of 30,165 (15.6%) transcripts were mapped to 323 Kyoto Encyclopedia of Genes and Genomes pathways. We also identified 41,973 simple sequence repeats, which can be used to generate markers for alfalfa, and 1,541 transcription factors were identified across 1,350 transcripts. Gene expression between dormant and non-dormant alfalfa at different time points were performed, and we identified several differentially expressed genes potentially related to fall dormancy. The Gene Ontology and pathways information were also identified. We sequenced and assembled the leaf transcriptome of alfalfa related to fall dormancy, and also identified some genes of interest involved in the fall dormancy mechanism. Thus, our research focused on studying fall dormancy in alfalfa through transcriptome sequencing. The sequencing and gene expression data generated in this study may be used further to elucidate the complete mechanisms governing fall dormancy in alfalfa.

  20. Weaned beef calves fed selenium-biofortified alfalfa hay have an enriched nasal microbiota compared with healthy controls.

    Directory of Open Access Journals (Sweden)

    Jean A Hall

    Full Text Available Selenium (Se is an essential trace mineral important for immune function and overall health of cattle. The nasopharyngeal microbiota in cattle plays an important role in overall respiratory health, especially when stresses associated with weaning, transport, and adaptation to a feedlot affect the normal respiratory defenses. Recent evidence suggests that cattle diagnosed with bovine respiratory disease complex have significantly less bacterial diversity. The objective of this study was to determine whether feeding weaned beef calves Se-enriched alfalfa (Medicago sativa hay for 9 weeks in a preconditioning program prior to entering the feedlot alters nasal microbiota. Recently weaned beef calves (n = 45 were blocked by sex and body weight, randomly assigned to 3 treatment groups with 3 pens of 5 calves per treatment group, and fed an alfalfa hay based diet for 9 weeks. Alfalfa hay was harvested from fields fertilized with sodium selenate at a rate of 0, 45.0 or 89.9 g Se/ha. Blood samples were collected biweekly and analyzed for whole-blood Se concentrations. Nasal swabs were collected during week 9 from one or two calves from each pen (total n = 16. Calculated Se intake from dietary sources was 3.0, 15.6, and 32.2 mg Se/head/day for calves consuming alfalfa hay with Se concentrations of 0.34 to 2.42 and 5.17 mg Se/kg dry matter, respectively. Whole-blood Se concentrations after 8 weeks of feeding Se-fertilized alfalfa hay were dependent upon Se-application rates (0, 45.0, or 89.9 g Se/ha and were 155, 345, and 504 ng/mL (PLinear < 0.0001. Microbial DNA was extracted from nasal swabs and amplified and sequenced. Alpha rarefaction curves comparing the species richness (observed OTUs and overall diversity (Chao1, Observed OTU, and Shannon index between calves fed selenium-biofortified alfalfa hay compared with control calves showed that Se-supplementation tended to be associated with an enriched nasal microbiota. ANOSIM of unweighted Uni