WorldWideScience

Sample records for aphid herbivores unaffected

  1. Young aphids avoid erroneous dropping when evading mammalian herbivores by combining input from two sensory modalities.

    Directory of Open Access Journals (Sweden)

    Moshe Gish

    Full Text Available Mammalian herbivores may incidentally ingest plant-dwelling insects while foraging. Adult pea aphids (Acyrthosiphon pisum avoid this danger by dropping off their host plant after sensing the herbivore's warm and humid breath and the vibrations it causes while feeding. Aphid nymphs may also drop (to escape insect enemies, but because of their slow movement, have a lower chance of finding a new plant. We compared dropping rates of first-instar nymphs with those of adults, after exposing pea aphids to different combinations of simulated mammalian breath and vibrations. We hypothesized that nymphs would compensate for the greater risk they face on the ground by interpreting more conservatively the mammalian herbivore cues they perceive. Most adults dropped in response to breath alone, but nymphs rarely did so. Breath stimulus accompanied by one concurrent vibrational stimulus, caused a minor rise in adult dropping rates. Adding a second vibration during breath had no additional effect on adults. The nymphs, however, relied on a combination of the two types of stimuli, with a threefold increase in dropping rates when the breath was accompanied by one vibration, and a further doubling of dropping rates when the second vibration was added. The age-specificity of the aphids' herbivore detection mechanism is probably an adaptation to the different cost of dropping for the different age groups. Relying on a combination of stimuli from two sensory modalities enables the vulnerable nymphs to avoid costly mistakes. Our findings emphasize the importance of the direct trophic effect of mammalian herbivory for plant-dwelling insects.

  2. The effect of plant inbreeding and stoichiometry on interactions with herbivores in nature: Echinacea angustifolia and its specialist aphid.

    Directory of Open Access Journals (Sweden)

    Caroline E Ridley

    Full Text Available Fragmentation of once widespread communities may alter interspecific interactions by changing genetic composition of interacting populations as well as their abundances and spatial distributions. In a long-term study of a fragmented population of Echinacea angustifolia, a perennial plant native to the North American prairie, we investigated influences on its interaction with a specialist aphid and tending ants. We grew plant progeny of sib-matings (I, and of random pairings within (W and between (B seven remnants in a common field within 8 km of the source remnants. During the fifth growing season, we determined each plant's burden of aphids and ants, as well as its size and foliar elemental composition (C, N, P. We also assayed composition (C, N of aphids and ants. Early in the season, progeny from genotypic classes B and I were twice as likely to harbor aphids, and in greater abundance, than genotypic class W; aphid loads were inversely related to foliar concentration of P and positively related to leaf N and plant size. At the end of the season, aphid loads were indistinguishable among genotypic classes. Ant abundance tracked aphid abundance throughout the season but showed no direct relationship with plant traits. Through its potential to alter the genotypic composition of remnant populations of Echinacea, fragmentation can increase Echinacea's susceptibility to herbivory by its specialist aphid and, in turn, perturb the abundance and distribution of aphids.

  3. 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.

  4. Toward a mechanistic understanding of competition in vascular-feeding herbivores: an empirical test of the sink competition hypothesis.

    Science.gov (United States)

    Kaplan, Ian; Sardanelli, Sandra; Rehill, Brian J; Denno, Robert F

    2011-07-01

    Recent evidence suggests that competitive interactions among herbivores are mostly indirect and mediated by plant responses to herbivory. Most studies, however, emphasize chewing insects and secondary chemistry, thus ignoring the diverse group of vascular-parasites that may be more likely to compete through induced changes in phytonutrients. Using an aboveground phloem-feeding aphid (Myzus persicae) and a belowground gall-forming nematode (Meloidogyne incognita) on tobacco plants, we assessed the importance of competition via induced host-plant sinks. In a series of experimental trials, nematode root herbivory caused 55 and 72% declines in the growth and fecundity of aphids, respectively. Aphids, on the other hand, did not impact nematode performance. Therefore, we predicted that nematodes out-compete M. persicae by attenuating the magnitude of aphid-induced sinks. Through a combination of invertase enzyme measurements and stable isotope ((13)C and (15)N) enrichment, we found evidence that both herbivores act as mobilizing sinks. Aphids attracted photoassimilates to feeding aggregations on leaves and nematode galls accumulated resources in the roots. Levels of invertase enzymes, for example, were more than fourfold higher in nematode galls than in surrounding root tissue. Yet we found no evidence supporting a sink competition model for aphid-nematode interactions. The strength of aphid-induced leaf sinks was entirely unaffected by nematode presence, and vice versa. Thus, induced host-plant sinks appear to be a common strategy employed by vascular parasites to manipulate the physiology of their host, but multi-sink competition may be limited to herbivores that co-occur on the same tissue type and/or plants under growth-limited abiotic conditions. PMID:21181415

  5. Rag1 aphid resistant soybeans alter the movement and distribution of soybean aphid (Hemiptera: Aphididae).

    Science.gov (United States)

    Whalen, Rebecca; Harmon, Jason P

    2012-12-01

    Herbivorous insects often move and distribute according to the quality of the plant they are on, and this behavior could influence interactions with plants bred for herbivore resistance. However, when an insect is normally considered sedentary, less is known about the potential importance of movement. We performed experiments to determine if a resistant soybean variety alters the movement and distribution, both within and between plants, of the soybean aphid Aphis glycines Matsumura. We did this by counting apterous aphids on leaves of resistant and susceptible soybean plants across several days. In individual plant tests aphid distribution was different between susceptible and resistant soybeans. Most notably aphids on resistant plants were quickly found off the original leaf on which they were placed and were ultimately distributed throughout the resistant soybean. Aphids on susceptible plants, however, tended to stay on their initial leaf of placement. Follow up experiments indicated this was primarily because of the movement of individuals and not differential demography on various plant parts. In experiments where aphids were able to walk to an adjacent plant there appeared to be a net movement of aphids off resistant plants and on to susceptible plants. Aphid populations on susceptible plants were higher when the plant was adjacent to a resistant plant than when adjacent to another susceptible plant. The effect of resistant plants on aphid movement and distribution could lead to unintended side-effects such as greater spread of plant viruses or altered effectiveness of biological control agents.

  6. Root-Lesion Nematodes Suppress Cabbage Aphid Population Development by Reducing Aphid Daily Reproduction.

    Science.gov (United States)

    Hol, W H G; Raaijmakers, Ciska E; Mons, Ilse; Meyer, Katrin M; van Dam, Nicole M

    2016-01-01

    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 modeling approach to analyze 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 female(-1) day(-1)) in comparison to both uninfested plants and plants with Meloidogyne spp. (3.50 offspring female(-1) day(-1)). 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.

  7. Nickel hyperaccumulation as an elemental defense of Streptanthus polygaloides (Brassicaceae): influence of herbivore feeding mode.

    Science.gov (United States)

    Jhee, Edward M; Boyd, Robert S; Eubanks, Micky D

    2005-11-01

    No study of a single nickel (Ni) hyperaccumulator species has investigated the impact of hyperaccumulation on herbivores representing a variety of feeding modes. Streptanthus polygaloides plants were grown on high- or low-Ni soils and a series of no-choice and choice feeding experiments was conducted using eight arthropod herbivores. Herbivores used were two leaf-chewing folivores (the grasshopper Melanoplus femurrubrum and the lepidopteran Evergestis rimosalis), a dipteran rhizovore (the cabbage maggot Delia radicum), a xylem-feeder (the spittlebug Philaenus spumarius), two phloem-feeders (the aphid, Lipaphis erysimi and the spidermite Trialeurodes vaporariorum) and two cell-disruptors (the bug Lygus lineolaris and the whitefly Tetranychus urticae). Hyperaccumulated Ni significantly decreased survival of the leaf-chewers and rhizovore, and significantly reduced population growth of the whitefly cell-disruptor. However, vascular tissue-feeding insects were unaffected by hyperaccumulated Ni, as was the bug cell-disruptor. We conclude that Ni can defend against tissue-chewing herbivores but is ineffective against vascular tissue-feeding herbivores. The effects of Ni on cell-disruptors varies, as a result of either variation of insect Ni sensitivity or the location of Ni in S. polygaloides cells and tissues.

  8. Early interactions during the encounter of plants, aphids and arboviruses.

    Science.gov (United States)

    Bak, Aurélie; Martinière, Alexandre; Blanc, Stéphane; Drucker, Martin

    2013-06-01

    Aphids infest many plants and cause damage by depriving them of nutrients and by transmitting many viral diseases. Aphid infestation and arbovirus transmission are controlled by establishment (or not) of a compatible reaction between the insects and the plants. This reaction is the result of defense reactions of the plant and counter-defense reactions of the parasite. Contrarily to plant-bacteria, plant-fungi and plant-herbivorous insects pathosystems, the plant-aphid pathosystem is understudied, although recent advances have begun to uncover some of its details. Especially the very early steps in plant-aphid interactions are hardly known. We here resume the present knowledge of these interactions. We discuss further how an aphid-transmitted plant virus that is transmitted during the first moments of the plant-aphid encounter, might help to study the very early plant aphid interactions.

  9. 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.

  10. Plant-mediated 'apparent effects' between mycorrhiza and insect herbivores.

    Science.gov (United States)

    Gilbert, Lucy; Johnson, David

    2015-08-01

    Plants mediate indirect 'apparent' effects between above-ground herbivores and below-ground mutualistic mycorrhizal fungi. The herbivore-plant-mycorrhiza continuum is further complicated because signals produced by plants in response to herbivores can be transmitted to other plants via shared fungal networks below ground. Insect herbivores, such as aphids, probably affect the functioning of mycorrhizal fungi by changing the supply of recent photosynthate from plants to mycorrhizas, whereas there is evidence that mycorrhizas affect aphid fitness by changing plant signalling pathways, rather than only through improved nutrition. New knowledge of the transfer of signals through fungal networks between plant species means we now need a better understanding of how this process occurs in relation to the feeding preferences of herbivores to shape plant community composition and herbivore behaviour in nature.

  11. Downstairs drivers--root herbivores shape communities of above-ground herbivores and natural enemies via changes in plant nutrients.

    Science.gov (United States)

    Johnson, Scott N; Mitchell, Carolyn; McNicol, James W; Thompson, Jacqueline; Karley, Alison J

    2013-09-01

    1. Terrestrial food webs are woven from complex interactions, often underpinned by plant-mediated interactions between herbivores and higher trophic groups. Below- and above-ground herbivores can influence one another via induced changes to a shared host plant, potentially shaping the wider community. However, empirical evidence linking laboratory observations to natural field populations has so far been elusive. 2. This study investigated how root-feeding weevils (Otiorhynchus sulcatus) influence different feeding guilds of herbivore (phloem-feeding aphids, Cryptomyzus galeopsidis, and leaf-chewing sawflies, Nematus olfaciens) in both controlled and field conditions. 3. We hypothesized that root herbivore-induced changes in plant nutrients (C, N, P and amino acids) and defensive compounds (phenolics) would underpin the interactions between root and foliar herbivores, and ultimately populations of natural enemies of the foliar herbivores in the field. 4. Weevils increased field populations of aphids by ca. 700%, which was followed by an increase in the abundance of aphid natural enemies. Weevils increased the proportion of foliar essential amino acids, and this change was positively correlated with aphid abundance, which increased by 90% on plants with weevils in controlled experiments. 5. In contrast, sawfly populations were 77% smaller during mid-June and adult emergence delayed by >14 days on plants with weevils. In controlled experiments, weevils impaired sawfly growth by 18%, which correlated with 35% reductions in leaf phosphorus caused by root herbivory, a previously unreported mechanism for above-ground-below-ground herbivore interactions. 6. This represents a clear demonstration of root herbivores affecting foliar herbivore community composition and natural enemy abundance in the field via two distinct plant-mediated nutritional mechanisms. Aphid populations, in particular, were initially driven by bottom-up effects (i.e. plant-mediated effects of root

  12. Inter-varietal interactions among plants in genotypically diverse mixtures tend to decrease herbivore performance.

    Science.gov (United States)

    Grettenberger, Ian M; Tooker, John F

    2016-09-01

    Much research has explored the effects of plant species diversity on herbivore populations, but far less has considered effects of plant genotypic diversity, or how abiotic stressors, like drought, can modify effects. Mechanisms by which plant genotypic diversity affects herbivore populations remain largely unresolved. We used greenhouse studies with a model system of wheat (Triticum aestivum L.) and bird cherry-oat aphid (Rhopalosiphum padi L.) to determine whether the genotypic diversity of a plant's neighborhood influences performance and fitness of herbivores on a focal plant and if drought changes the influence of neighborhood diversity. Taken across all varieties we tested, plant-plant interactions in diverse neighborhoods reduced aphid performance and generated associational resistance, although effects on aphids depended on variety identity. In diverse mixtures, drought stress greatly diminished the genotypic diversity-driven reduction in aphid performance. Neighborhood diversity influenced mother aphid size, and appeared to partially explain how plant-plant interactions reduced the number of offspring produced in mixtures. Plant size did not mediate effects on aphid performance, although neighborhood diversity reduced plant mass across varieties and watering treatments. Our results suggest inter-varietal interactions in genotypic mixtures can affect herbivore performance in the absence of herbivore movement and that abiotic stress may diminish any effects. Accounting for how neighborhood diversity influences resistance of an individual plant to herbivores will help aid development of mixtures of varieties for managing insect pests and clarify the role of plant genotypic diversity in ecosystems. PMID:27170329

  13. Antagonistic effects of soybean viruses on soybean aphid performance.

    Science.gov (United States)

    Donaldson, Jack R; Gratton, Claudio

    2007-08-01

    Although there is long-standing recognition that pest complexes require different management approaches than individual pests, relatively little research has explored how pests interact. In particular, little is known of how herbivorous insects and plant pathogens interact when sharing the same host plant. The soybean aphid, Aphis glycines Mastumura, a recently introduced pest of soybean in the upper midwestern United States, and a complex of plant viruses vectored to soybean by insects have become a major concern for growers in the region. Given the abundance of soybean aphid and the increase in virus incidence in recent years, soybean aphids often use soybean infected by plant viral pathogens. We tested the hypothesis that soybean aphid performance is affected by virus infection of soybean plants. We conducted a series of field and laboratory experiments that examined how infection of soybeans with the common plant viruses, alfalfa mosaic, soybean mosaic, and bean pod mottle viruses, influenced soybean aphid performance. Soybean plants (in the field and laboratory) were hand inoculated with individual viruses, and aphids were allowed to colonize plants naturally in field experiments or added to the plants in clip-cages or within mesh bags in laboratory assays. In the field, aphid density on uninfected control soybean plants was nearly double that on infected plants. In laboratory assays, aphid population growth rates were on average 20% lower for aphids on virus infected compared with uninfected plants. Life table analyses showed that increased mortality on virus-infected plants likely explain differences in aphid population growth. Although there was some heterogeneity in the significance of treatment effects among different experiments, when independent experiments are taken together, there is on average an overall negative effect of these viruses on soybean aphids. PMID:17716484

  14. Complex effects of fertilization on plant and herbivore performance in the presence of a plant competitor and activated carbon.

    Directory of Open Access Journals (Sweden)

    Nafiseh Mahdavi-Arab

    Full Text Available Plant-herbivore interactions are influenced by host plant quality which in turn is affected by plant growth conditions. Competition is the major biotic and nutrient availability a major abiotic component of a plant's growth environment. Yet, surprisingly few studies have investigated impacts of competition and nutrient availability on herbivore performance and reciprocal herbivore effects on plants. We studied growth of the specialist aphid, Macrosiphoniella tanacetaria, and its host plant tansy, Tanacetum vulgare, under experimental addition of inorganic and organic fertilizer crossed with competition by goldenrod, Solidago canadensis. Because of evidence that competition by goldenrod is mediated by allelopathic compounds, we also added a treatment with activated carbon. Results showed that fertilization increased, and competition with goldenrod decreased, plant biomass, but this was likely mediated by resource competition. There was no evidence from the activated carbon treatment that allelopathy played a role which instead had a fertilizing effect. Aphid performance increased with higher plant biomass and depended on plant growth conditions, with fertilization and AC increasing, and plant competition decreasing aphid numbers. Feedbacks of aphids on plant performance interacted with plant growth conditions in complex ways depending on the relative magnitude of the effects on plant biomass and aphid numbers. In the basic fertilization treatment, tansy plants profited from increased nutrient availability by accumulating more biomass than they lost due to an increased number of aphids under fertilization. When adding additional fertilizer, aphid numbers increased so high that tansy plants suffered and showed reduced biomass compared with controls without aphids. Thus, the ecological cost of an infestation with aphids depends on the balance of effects of growth conditions on plant and herbivore performance. These results emphasize the importance

  15. Complex effects of fertilization on plant and herbivore performance in the presence of a plant competitor and activated carbon.

    Science.gov (United States)

    Mahdavi-Arab, Nafiseh; Meyer, Sebastian T; Mehrparvar, Mohsen; Weisser, Wolfgang W

    2014-01-01

    Plant-herbivore interactions are influenced by host plant quality which in turn is affected by plant growth conditions. Competition is the major biotic and nutrient availability a major abiotic component of a plant's growth environment. Yet, surprisingly few studies have investigated impacts of competition and nutrient availability on herbivore performance and reciprocal herbivore effects on plants. We studied growth of the specialist aphid, Macrosiphoniella tanacetaria, and its host plant tansy, Tanacetum vulgare, under experimental addition of inorganic and organic fertilizer crossed with competition by goldenrod, Solidago canadensis. Because of evidence that competition by goldenrod is mediated by allelopathic compounds, we also added a treatment with activated carbon. Results showed that fertilization increased, and competition with goldenrod decreased, plant biomass, but this was likely mediated by resource competition. There was no evidence from the activated carbon treatment that allelopathy played a role which instead had a fertilizing effect. Aphid performance increased with higher plant biomass and depended on plant growth conditions, with fertilization and AC increasing, and plant competition decreasing aphid numbers. Feedbacks of aphids on plant performance interacted with plant growth conditions in complex ways depending on the relative magnitude of the effects on plant biomass and aphid numbers. In the basic fertilization treatment, tansy plants profited from increased nutrient availability by accumulating more biomass than they lost due to an increased number of aphids under fertilization. When adding additional fertilizer, aphid numbers increased so high that tansy plants suffered and showed reduced biomass compared with controls without aphids. Thus, the ecological cost of an infestation with aphids depends on the balance of effects of growth conditions on plant and herbivore performance. These results emphasize the importance to investigate both

  16. Relationships Between Aphids (Insecta: Homoptera: Aphididae) and Slugs (Gastropoda: Stylommatophora: Agriolimacidae) Pests of Legumes (Fabaceae: Lupinus).

    Science.gov (United States)

    Kozłowski, Jan; Strażyński, Przemysław; Jaskulska, Monika; Kozłowska, Maria

    2016-01-01

    Lupin plants are frequently damaged by various herbivorous invertebrates. Significant among these are slugs and aphids, which sometimes attack the same plants. Relationships between aphids, slugs and food plant are very interesting. Grazing by these pests on young plants can lead to significant yield losses. There is evidence that the alkaloids present in some lupin plants may reduce grazing by slugs, aphids and other invertebrates. In laboratory study was analyzed the relationships between aphid Aphis craccivora and slug Deroceras reticulatum pests of legumes Lupinus angustifolius. It was found that the presence of aphids significantly reduced slug grazing on the plants. The lupin cultivars with high alkaloid content were found to be less heavily damaged by D. reticulatum, and the development of A. craccivora was found to be inhibited on such plants. PMID:27324580

  17. 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.

  18. Arabidopsis thaliana—Aphid Interaction

    OpenAIRE

    Louis, Joe; Singh, Vijay,; Shah, Jyoti

    2012-01-01

    Aphids are important pests of plants that use their stylets to tap into the sieve elements to consume phloem sap. Besides the removal of photosynthates, aphid infestation also alters source-sink patterns. Most aphids also vector viral diseases. In this chapter, we will summarize on recent significant findings in plant-aphid interaction, and how studies involving Arabidopsis thaliana and Myzus persicae (Sülzer), more commonly known as the green peach aphid (GPA), are beginning to provide impor...

  19. Feeding behaviour and performance of different populations of the black currant-lettuce aphid, Nasonovia ribisnigri, on resistant and susceptible lettuce

    NARCIS (Netherlands)

    Broeke, ten C.J.M.; Dicke, M.; Loon, van J.J.A.

    2013-01-01

    When crops are bred for resistance to herbivores, these herbivores are under strong selection pressure to overcome this resistance, which may result in the emergence of virulent biotypes. This is a growing problem for crop species attacked by aphids. The Nr-gene in lettuce confers near-complete resi

  20. Volatiles from Plants Induced by Multiple Aphid Attacks Promote Conidial Performance of Lecanicillium lecanii.

    Science.gov (United States)

    Lin, Yongwen; Hussain, Mubasher; Avery, Pasco Bruce; Qasim, Muhammad; Fang, Dalin; Wang, Liande

    2016-01-01

    Herbivore-induced plant volatiles (HIPVs) are clues that help predatory insects search for food. The hypothesis that entomopathogenic fungi, which protect plants, benefit from the release of HIPVs was tested. The plant Arabidopsis thaliana was used as the source of HIPVs. The insect herbivore Lipaphis erysimi (Kaltenbach) was used as the inducer, and the fungal pathogen of the aphid Lecanicillium lecanii was exposed to HIPVs to test our hypothesis. When exposed to aphid-induced A. thaliana volatiles, the mortality of aphids pre-treated with a conidial suspension of L. lecanii, the conidial germination and the appressorial formation were significantly increased compared with the control. The decan-3-ol and 4-methylpentyl isothiocyanate that were detected in the headspace seemed to have positive and negative affection, respectively. Moreover, HIPVs generated from groups of eight aphids per plant promoted significantly increased conidial germination and appressorial formation compared with HIPVs from groups of one, two and four aphids per plant. Our results demonstrated that the pathogenicity of the entomopathogenic fungus L. lecanii was enhanced when exposed to HIPVs and that the HIPVs were affected by the number of insect herbivores that induced them. PMID:26999795

  1. Volatiles from Plants Induced by Multiple Aphid Attacks Promote Conidial Performance of Lecanicillium lecanii.

    Directory of Open Access Journals (Sweden)

    Yongwen Lin

    Full Text Available Herbivore-induced plant volatiles (HIPVs are clues that help predatory insects search for food. The hypothesis that entomopathogenic fungi, which protect plants, benefit from the release of HIPVs was tested. The plant Arabidopsis thaliana was used as the source of HIPVs. The insect herbivore Lipaphis erysimi (Kaltenbach was used as the inducer, and the fungal pathogen of the aphid Lecanicillium lecanii was exposed to HIPVs to test our hypothesis. When exposed to aphid-induced A. thaliana volatiles, the mortality of aphids pre-treated with a conidial suspension of L. lecanii, the conidial germination and the appressorial formation were significantly increased compared with the control. The decan-3-ol and 4-methylpentyl isothiocyanate that were detected in the headspace seemed to have positive and negative affection, respectively. Moreover, HIPVs generated from groups of eight aphids per plant promoted significantly increased conidial germination and appressorial formation compared with HIPVs from groups of one, two and four aphids per plant. Our results demonstrated that the pathogenicity of the entomopathogenic fungus L. lecanii was enhanced when exposed to HIPVs and that the HIPVs were affected by the number of insect herbivores that induced them.

  2. Heterodera schachtii nematodes interfere with aphid-plant relations on Brassica oleracea

    NARCIS (Netherlands)

    Hol, W.H.G.; Boer, de W.; Termorshuizen, A.J.; Meyer, K.M.; Schneider, J.H.M.; Putten, van der W.H.; Dam, N.M.

    2013-01-01

    Aboveground and belowground herbivore species modify plant defense responses differently. Simultaneous attack can lead to non-additive effects on primary and secondary metabolite composition in roots and shoots. We previously found that aphid (Brevicoryne brassicae) population growth on Brassica ole

  3. Aphid and ladybird beetle abundance depend on the interaction of spatial effects and genotypic diversity.

    Science.gov (United States)

    Genung, Mark A; Crutsinger, Gregory M; Bailey, Joseph K; Schweitzer, Jennifer A; Sanders, Nathan J

    2012-01-01

    Intraspecific variation and genotypic diversity of host-plants can affect the structure of associated arthropod communities and the dynamics of populations. Similarly, neighboring plants can also affect interactions between host-plants and their associated arthropods. However, most studies on the effects of host-plant genotypes have largely ignored the potential effects of neighboring host-plants on arthropod communities. In this study, we used a common garden experiment to ask how spatial effects of neighboring patches, along with genotype identity and genotypic diversity in tall goldenrod (Solidago altissima), affect the abundances of a common goldenrod herbivore (Uroleucon nigrotuberculatum) and their dominant predator (Harmonia axyridis, a ladybird beetle). Aphid abundance varied 80-fold among genotypes, while ladybird beetle abundance was not affected by genotype identity. Additionally, there were strong effects of neighboring plots: aphid abundance in a focal plot was positively correlated to aphid abundance in nearby plots, suggesting strong spatial patterning in the abundance of aphids. Neither aphid nor ladybird beetle abundance was affected by genotypic diversity. However, focal plot genotypic diversity mediated the strength of the neighborhood effect (i.e., strong effects for genotype polyculture focal plots and weak effects for genotype monoculture focal plots). Our results show that aphids were directly influenced by host-plant genotype identity while ladybird beetles responded mainly to prey abundance, and suggest that genotypic diversity can influence the effects of spatial processes on the plant-herbivore interactions. PMID:21805301

  4. Drought and root herbivory interact to alter the response of above-ground parasitoids to aphid infested plants and associated plant volatile signals

    OpenAIRE

    Muhammad Tariq; Wright, Denis J.; Bruce, Toby J. A.; Staley, Joanna T.

    2013-01-01

    Multitrophic interactions are likely to be altered by climate change but there is little empirical evidence relating the responses of herbivores and parasitoids to abiotic factors. Here we investigated the effects of drought on an above/below-ground system comprising a generalist and a specialist aphid species (foliar herbivores), their parasitoids, and a dipteran species (root herbivore).We tested the hypotheses that: (1) high levels of drought stress and below-ground herbivory interact to r...

  5. Genetic mapping shows intraspecific variation and transgressive segregation for caterpillar-induced aphid resistance in maize.

    Science.gov (United States)

    Tzin, Vered; Lindsay, Penelope L; Christensen, Shawn A; Meihls, Lisa N; Blue, Levi B; Jander, Georg

    2015-11-01

    Plants in nature have inducible defences that sometimes lead to targeted resistance against particular herbivores, but susceptibility to others. The metabolic diversity and genetic resources available for maize (Zea mays) make this a suitable system for a mechanistic study of within-species variation in such plant-mediated interactions between herbivores. Beet armyworms (Spodoptera exigua) and corn leaf aphids (Rhopalosiphum maidis) are two naturally occurring maize herbivores with different feeding habits. Whereas chewing herbivore-induced methylation of 2,4-dihydroxy-7-methoxy-1,4-benzoxazin-3-one glucoside (DIMBOA-Glc) to form 2-hydroxy-4,7-dimethoxy-1,4-benzoxazin-3-one glucoside (HDMBOA-Glc) promotes caterpillar resistance, lower DIMBOA-Glc levels favour aphid reproduction. Thus, caterpillar-induced DIMBOA-Glc methyltransferase activity in maize is predicted to promote aphid growth. To test this hypothesis, the impact of S. exigua feeding on R. maidis progeny production was assessed using seventeen genetically diverse maize inbred lines. Whereas aphid progeny production was increased by prior caterpillar feeding on lines B73, Ki11, Ki3 and Tx303, it decreased on lines Ky21, CML103, Mo18W and W22. Genetic mapping of this trait in a population of B73 × Ky21 recombinant inbred lines identified significant quantitative trait loci on maize chromosomes 1, 7 and 10. There is a transgressive segregation for aphid resistance, with the Ky21 alleles on chromosomes 1 and 7 and the B73 allele on chromosome 10 increasing aphid progeny production. The chromosome 1 QTL coincides with a cluster of three maize genes encoding benzoxazinoid O-methyltransferases that convert DIMBOA-Glc to HDMBOA-Glc. Gene expression studies and benzoxazinoid measurements indicate that S. exigua -induced responses in this pathway differentially affect R. maidis resistance in B73 and Ky21. PMID:26462033

  6. Avoidance and tolerance to avian herbivores in aquatic plants

    OpenAIRE

    Hidding, A.

    2009-01-01

    Tolerance and avoidance are the two contrasting strategies that plants may adopt to cope with herbivores. Tolerance traits define the degree to which communities remain unaffected by herbivory. Trade-offs between herbivore avoidance and competitive strength and between avoidance and colonization ability may shape population traits and communities under herbivory. In this thesis I present comparative and experimental studies on populations and communities of aquatic plants and how they deal wi...

  7. Effects of elevated temperature and CO2 on aboveground-belowground systems: a case study with plants, their mutualistic bacteria and root / shoot herbivores

    Directory of Open Access Journals (Sweden)

    James Michael William Ryalls

    2013-11-01

    Full Text Available Interactions between above- and belowground herbivores have been prominent in the field of aboveground-belowground ecology from the outset, although little is known about how climate change affects these organisms when they share the same plant. Additionally, the interactive effects of multiple factors associated with climate change such as elevated temperature (eT and elevated atmospheric carbon dioxide (eCO2 are untested. We investigated how eT and eCO2 affected larval development of the lucerne weevil (Sitona discoideus and colonisation by the pea aphid (Acyrthosiphon pisum, on three cultivars of a common host plant, lucerne (Medicago sativa. Sitona discoideus larvae feed on root nodules housing N2-fixing rhizobial bacteria, allowing us to test the effects of eT and eCO2 on three trophic levels. Moreover, we assessed the influence of these factors on plant growth. eT increased plant growth rate initially (6, 8 and 10 weeks after sowing, with cultivar ‘Sequel’ achieving the greatest height. Inoculation with aphids, however, reduced plant growth at week 14. eT severely reduced root nodulation by 43%, whereas eCO2 promoted nodulation by 56%, but only at ambient temperatures. Weevil presence increased net root biomass and nodulation, by 31 and 45%, respectively, showing an overcompensatory plant growth response. Effects of eT and eCO2 on root nodulation were mirrored by weevil larval development; eT and eCO2 reduced and increased larval development, respectively. Contrary to expectations, aphid colonisation was unaffected by eT or eCO2, but there was a near-significant 10% reduction in colonisation rates on plants with weevils present belowground. The contrasting effects of eT and eCO2 on weevils potentially occurred through changes in root nodulation patterns.

  8. 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. PMID:27536306

  9. Pea aphid promotes amino acid metabolism both in Medicago truncatula and bacteriocytes to favor aphid population growth under elevated CO2.

    Science.gov (United States)

    Guo, Huijuan; Sun, Yucheng; Li, Yuefei; Tong, Bin; Harris, Marvin; Zhu-Salzman, Keyan; Ge, Feng

    2013-10-01

    Rising atmospheric CO(2) levels can dilute the nitrogen (N) resource in plant tissue, which is disadvantageous to many herbivorous insects. Aphids appear to be an exception that warrants further study. The effects of elevated CO(2) (750 ppm vs. 390 ppm) were evaluated on N assimilation and transamination by two Medicago truncatula genotypes, a N-fixing-deficient mutant (dnf1) and its wild-type control (Jemalong), with and without pea aphid (Acyrthosiphon pisum) infestation. Elevated CO(2) increased population abundance and feeding efficiency of aphids fed on Jemalong, but reduced those on dnf1. Without aphid infestation, elevated CO(2) increased photosynthetic rate, chlorophyll content, nodule number, biomass, and pod number for Jemalong, but only increased pod number and chlorophyll content for dnf1. Furthermore, aphid infested Jemalong plants had enhanced activities of N assimilation-related enzymes (glutamine synthetase, Glutamate synthase) and transamination-related enzymes (glutamate oxalate transaminase, glutamine phenylpyruvate transaminase), which presumably increased amino acid concentration in leaves and phloem sap under elevated CO(2). In contrast, aphid infested dnf1 plants had decreased activities of N assimilation-related enzymes and transmination-related enzymes and amino acid concentrations under elevated CO(2). Furthermore, elevated CO(2) up-regulated expression of genes relevant to amino acid metabolism in bacteriocytes of aphids associated with Jemalong, but down-regulated those associated with dnf1. Our results suggest that pea aphids actively elicit host responses that promote amino acid metabolism in both the host plant and in its bacteriocytes to favor the population growth of the aphid under elevated CO(2).

  10. 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.

  11. Reciprocal interactions between native and introduced populations of common milkweed, Asclepias syriaca, and the specialist aphid, Aphis nerii

    NARCIS (Netherlands)

    Bukovinszky, T.; Gols, R.; Agrawal, A.A.; Roge, C.; Bezemer, T.M.; Biere, A.; Harvey, J.A.

    2014-01-01

    Following its introduction into Europe (EU), the common milkweed (Asclepias syriaca) has been free of most specialist herbivores that are present in its native North American (NA) range, except for the oleander aphid Aphis nerii. We compared EU and NA populations of A. nerii on EU and NA milkweed po

  12. Effect of herbivore damage on broad leaf motion in wind

    Science.gov (United States)

    Burnett, Nicholas; Kothari, Adit

    2015-11-01

    Terrestrial plants regularly experience wind that imposes aerodynamic forces on the plants' leaves. Passive leaf motion (e.g. fluttering) and reconfiguration (e.g. rolling into a cone shape) in wind can affect the drag on the leaf. In the study of passive leaf motion in wind, little attention has been given to the effect of herbivory. Herbivores may alter leaf motion in wind by making holes in the leaf. Also, a small herbivore (e.g. snail) on a leaf can act as a point mass, thereby affecting the leaf's motion in wind. Conversely, accelerations imposed on an herbivore sitting on a leaf by the moving leaf may serve as a defense by dislodging the herbivore. In the present study, we investigated how point masses (>1 g) and holes in leaves of the tuliptree affected passive leaf motion in turbulent winds of 1 and 5 m s-1. Leaf motion was unaffected by holes in the leaf surface (about 10% of leaf area), but an herbivore's mass significantly damped the accelerations of fluttering leaves. These results suggest that an herbivore's mass, but not the damage it inflicts, can affect leaf motion in the wind. Furthermore, the damping of leaf fluttering from an herbivore's mass may prevent passive leaf motions from being an effective herbivore defense.

  13. Sink-source interactions between a galling aphid and its narrowleaf cottonwood host: Within and between plant variation

    International Nuclear Information System (INIS)

    The authors examined within and between plant variation in the capacity of the leaf gallin aphid, Pemphigus betae, to manipulate the sink-source translocation patterns of its host, narrowleaf cottonwood (Populus angustifolia). Within a plant, a series of 14C-labeling experiments showed that P. betae actively manipulated host translocation patterns by acting as a strong sink and fed on assimilates produced in surrounding plant tissues serving as sources. Food resources drawn into the galled leaf from storage tissues in the stem and from surrounding leaves were a major resource for this herbivore in addition to resources from the galled leaf blade. Aphids compete for resources with natural plant sinks, such as developing fruits. In common gardens containing aphid resistant and aphid susceptible clones, I tested the hypothesis that aphid gall success on resistant trees is limited by competition between aphid-induced sinks and the plant's natural sinks, and that the intensity of intraplant competition was determined by the genetically determined architecture of the tree. Through bud removal, a resistant clone could be given the architecture of a susceptible clone. Aphid survival was increased two fold on architecturally modified resistant clones

  14. Contrasting effects of large herbivore grazing on smaller herbivores

    NARCIS (Netherlands)

    Bakker, E. S.; Olff, H.; Gleichman, J. M.

    2009-01-01

    Assemblages of large herbivores may compete For food or facilitate one another. However, small vertebrate herbivore species co-occurring with large herbivores may be affected by large herbivore grazing through changes in plant species composition, nutrient content and vegetation structure. These cha

  15. Leaf Colour as a Signal of Chemical Defence to Insect Herbivores in Wild Cabbage (Brassica oleracea).

    Science.gov (United States)

    Green, Jonathan P; Foster, Rosie; Wilkins, Lucas; Osorio, Daniel; Hartley, Susan E

    2015-01-01

    Leaf colour has been proposed to signal levels of host defence to insect herbivores, but we lack data on herbivory, leaf colour and levels of defence for wild host populations necessary to test this hypothesis. Such a test requires measurements of leaf spectra as they would be sensed by herbivore visual systems, as well as simultaneous measurements of chemical defences and herbivore responses to leaf colour in natural host-herbivore populations. In a large-scale field survey of wild cabbage (Brassica oleracea) populations, we show that variation in leaf colour and brightness, measured according to herbivore spectral sensitivities, predicts both levels of chemical defences (glucosinolates) and abundance of specialist lepidopteran (Pieris rapae) and hemipteran (Brevicoryne brassicae) herbivores. In subsequent experiments, P. rapae larvae achieved faster growth and greater pupal mass when feeding on plants with bluer leaves, which contained lower levels of aliphatic glucosinolates. Glucosinolate-mediated effects on larval performance may thus contribute to the association between P. rapae herbivory and leaf colour observed in the field. However, preference tests found no evidence that adult butterflies selected host plants based on leaf coloration. In the field, B. brassicae abundance varied with leaf brightness but greenhouse experiments were unable to identify any effects of brightness on aphid preference or performance. Our findings suggest that although leaf colour reflects both levels of host defences and herbivore abundance in the field, the ability of herbivores to respond to colour signals may be limited, even in species where performance is correlated with leaf colour.

  16. 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

    using these endophytes for the biological control of aphids and other herbivores under greenhouse and field conditions.

  17. Enemy-free space promotes maintenance of host races in an aphid species.

    Science.gov (United States)

    Vosteen, Ilka; Gershenzon, Jonathan; Kunert, Grit

    2016-07-01

    The enormous biodiversity of herbivorous insects may arise from ecological speciation via continuous host-plant switches. Whether such switches are successful depends on the trade-off between different selection pressures that act on herbivores. Decreased herbivore performance due to suboptimal nutrition might be compensated for by a reduced natural enemy pressure. As a consequence, an "enemy-free space" on a certain plant might facilitate host-plant switches and maintain biotypes. To test this hypothesis, we used the pea aphid (Acyrthosiphon pisum) complex, which consists of at least 11 genetically distinct host races that are native to specific legume host plants but can all develop on the universal host plant Vicia faba. Three A. pisum host races native to Trifolium pratense, Pisum sativum, and Medicago sativa were investigated in experiments on their respective host plants and on the universal host plant V. faba. We found that hoverflies preferred to oviposit on P. sativum and the universal host V. faba. Since feeding by hoverfly larvae suppressed aphid population growth on these host plants, the native hosts M. sativa and T. pratense provided enemy-free space for the respective A. pisum races. Mobile predators, such as ants and ladybird beetles, preferred Pisum race aphids on V. faba over P. sativum. Thus, all three of the native host plants studied supply enemy-free space for A. pisum compared to the universal host V. faba. Reducing encounters between aphid races on V. faba would reduce gene flow among them and could contribute to maintaining the host races.

  18. Enemy-free space promotes maintenance of host races in an aphid species.

    Science.gov (United States)

    Vosteen, Ilka; Gershenzon, Jonathan; Kunert, Grit

    2016-07-01

    The enormous biodiversity of herbivorous insects may arise from ecological speciation via continuous host-plant switches. Whether such switches are successful depends on the trade-off between different selection pressures that act on herbivores. Decreased herbivore performance due to suboptimal nutrition might be compensated for by a reduced natural enemy pressure. As a consequence, an "enemy-free space" on a certain plant might facilitate host-plant switches and maintain biotypes. To test this hypothesis, we used the pea aphid (Acyrthosiphon pisum) complex, which consists of at least 11 genetically distinct host races that are native to specific legume host plants but can all develop on the universal host plant Vicia faba. Three A. pisum host races native to Trifolium pratense, Pisum sativum, and Medicago sativa were investigated in experiments on their respective host plants and on the universal host plant V. faba. We found that hoverflies preferred to oviposit on P. sativum and the universal host V. faba. Since feeding by hoverfly larvae suppressed aphid population growth on these host plants, the native hosts M. sativa and T. pratense provided enemy-free space for the respective A. pisum races. Mobile predators, such as ants and ladybird beetles, preferred Pisum race aphids on V. faba over P. sativum. Thus, all three of the native host plants studied supply enemy-free space for A. pisum compared to the universal host V. faba. Reducing encounters between aphid races on V. faba would reduce gene flow among them and could contribute to maintaining the host races. PMID:26520659

  19. Ant larval demand reduces aphid colony growth rates in an ant-aphid interaction

    OpenAIRE

    Cook, James M.; Leather, Simon R; Oliver, Tom H.

    2012-01-01

    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 exper...

  20. New Records of Aphid Fauna in Turkey

    OpenAIRE

    Kaygin, Azize Toper; Gorur, Gazi; Cota, Figen

    2010-01-01

    Three aphid species were identified as new records for Turkey aphid fauna from Bartin province. These species are Ceruraphis viburnicola (Gillette) (Hemiptera: Aphididae), Dysaphis apiifolia (Theobald) (Hemiptera: Aphididae) and Macrosiphum mordvilkoi Miyazaki (Hemiptera: Aphididae). These records increase the recorded aphid-fauna of Turkey to 433 species.

  1. 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

  2. Elevated CO2 decreases the response of the ethylene signaling pathway in Medicago truncatula and increases the abundance of the pea aphid.

    Science.gov (United States)

    Guo, Huijuan; Sun, Yucheng; Li, Yuefei; Liu, Xianghui; Zhang, Wenhao; Ge, Feng

    2014-01-01

    The performance of herbivorous insects is greatly affected by plant nutritional quality and resistance, which are likely to be altered by rising concentrations of atmospheric CO2 . We previously reported that elevated CO2 enhanced biological nitrogen (N) fixation of Medicago truncatula, which could result in an increased supply of amino acids to the pea aphid (Acyrthosiphon pisum). The current study examined the N nutritional quality and aphid resistance of sickle, an ethylene-insensitive mutant of M. truncatula with supernodulation, and its wild-type control A17 under elevated CO2 in open-top field chambers. Regardless of CO2 concentration, growth and amino acid content were greater and aphid resistance was lower in sickle than in A17. Elevated CO2 up-regulated N assimilation and transamination-related enzymes activities and increased phloem amino acids in both genotypes. Furthermore, elevated CO2 down-regulated expression of 1-amino-cyclopropane-carboxylic acid (ACC), sickle gene (SKL) and ethylene response transcription factors (ERF) genes in the ethylene signaling pathway of A17 when infested by aphids and decreased resistance against aphids in terms of lower activities of superoxide dismutase (SOD), peroxidase (POD), and polyphenol oxidase (PPO). Our results suggest that elevated CO2 suppresses the ethylene signaling pathway in M. truncatula, which results in an increase in plant nutritional quality for aphids and a decrease in plant resistance against aphids.

  3. Drought and root herbivory interact to alter the response of above-ground parasitoids to aphid infested plants and associated plant volatile signals.

    Directory of Open Access Journals (Sweden)

    Muhammad Tariq

    Full Text Available Multitrophic interactions are likely to be altered by climate change but there is little empirical evidence relating the responses of herbivores and parasitoids to abiotic factors. Here we investigated the effects of drought on an above/below-ground system comprising a generalist and a specialist aphid species (foliar herbivores, their parasitoids, and a dipteran species (root herbivore.We tested the hypotheses that: (1 high levels of drought stress and below-ground herbivory interact to reduce the performance of parasitoids developing in aphids; (2 drought stress and root herbivory change the profile of volatile organic chemicals (VOCs emitted by the host plant; (3 parasitoids avoid ovipositing in aphids feeding on plants under drought stress and root herbivory. We examined the effect of drought, with and without root herbivory, on the olfactory response of parasitoids (preference, plant volatile emissions, parasitism success (performance, and the effect of drought on root herbivory. Under drought, percentage parasitism of aphids was reduced by about 40-55% compared with well watered plants. There was a significant interaction between drought and root herbivory on the efficacy of the two parasitoid species, drought stress partially reversing the negative effect of root herbivory on percent parasitism. In the absence of drought, root herbivory significantly reduced the performance (e.g. fecundity of both parasitoid species developing in foliar herbivores. Plant emissions of VOCs were reduced by drought and root herbivores, and in olfactometer experiments parasitoids preferred the odour from well-watered plants compared with other treatments. The present work demonstrates that drought stress can change the outcome of interactions between herbivores feeding above- and below-ground and their parasitoids, mediated by changes in the chemical signals from plants to parasitoids. This provides a new insight into how the structure of terrestrial

  4. Drought and root herbivory interact to alter the response of above-ground parasitoids to aphid infested plants and associated plant volatile signals.

    Science.gov (United States)

    Tariq, Muhammad; Wright, Denis J; Bruce, Toby J A; Staley, Joanna T

    2013-01-01

    Multitrophic interactions are likely to be altered by climate change but there is little empirical evidence relating the responses of herbivores and parasitoids to abiotic factors. Here we investigated the effects of drought on an above/below-ground system comprising a generalist and a specialist aphid species (foliar herbivores), their parasitoids, and a dipteran species (root herbivore).We tested the hypotheses that: (1) high levels of drought stress and below-ground herbivory interact to reduce the performance of parasitoids developing in aphids; (2) drought stress and root herbivory change the profile of volatile organic chemicals (VOCs) emitted by the host plant; (3) parasitoids avoid ovipositing in aphids feeding on plants under drought stress and root herbivory. We examined the effect of drought, with and without root herbivory, on the olfactory response of parasitoids (preference), plant volatile emissions, parasitism success (performance), and the effect of drought on root herbivory. Under drought, percentage parasitism of aphids was reduced by about 40-55% compared with well watered plants. There was a significant interaction between drought and root herbivory on the efficacy of the two parasitoid species, drought stress partially reversing the negative effect of root herbivory on percent parasitism. In the absence of drought, root herbivory significantly reduced the performance (e.g. fecundity) of both parasitoid species developing in foliar herbivores. Plant emissions of VOCs were reduced by drought and root herbivores, and in olfactometer experiments parasitoids preferred the odour from well-watered plants compared with other treatments. The present work demonstrates that drought stress can change the outcome of interactions between herbivores feeding above- and below-ground and their parasitoids, mediated by changes in the chemical signals from plants to parasitoids. This provides a new insight into how the structure of terrestrial communities may be

  5. Efficacy of Chemical Mimicry by Aphid Predators Depends on Aphid-Learning by Ants.

    Science.gov (United States)

    Hayashi, Masayuki; Nomura, Masashi; Nakamuta, Kiyoshi

    2016-03-01

    Chemical mimicry is an effective strategy when signal receivers recognize and discriminate models by relying on chemical cues. Some aphid enemies mimic the cuticular chemicals of aphids through various means thus avoiding detection and attack by aphid-tending ants. However, because ants have been reported to learn the chemical signatures of aphids in order to distinguish the aphids, the efficacy of chemical mimicry is predicted to depend on the experience of the ants that had tended aphids. The present study tested this hypothesis using two predator species: larvae of the green lacewing Mallada desjardinsi, and larvae of the ladybeetle Scymnus posticalis. Lacewing larvae carry the carcasses of aphids on which they have preyed upon their backs, and these function via chemical camouflage to reduce the aggressiveness of aphid-tending ants toward the larvae. Ladybeetle larvae reportedly produce a covering of wax structures, and their chemicals appear to attenuate ant aggression. We examined whether the behavior of the ant Tetramorium tsushimae toward these predators changed depending on their aphid-tending experience. Ants moderated their aggressiveness toward both predators when they had previously tended aphids, indicating that chemical mimicry by both aphid predators is dependent on previous experience of the ants in tending aphids. Chemical mimicry by the predators of ant-tended aphids is therefore considered to exploit learning-dependent aphid recognition systems of ants.

  6. Role of terpenes from aphid-infested potato on searching and oviposition behavior of Episyrphus balteatus

    Institute of Scientific and Technical Information of China (English)

    NICOLAS HARMEL; RAKI ALMOHAMAD; MARIE-LAURE FAUCONNIER; PATRICK DU JARDIN; FRANCO IS VERHEGGEN; MICHEL MARLIER; ERIC HAUBRUGE; FR(E)D(E)RIC FRANCIS

    2007-01-01

    To cope with pathogen and insect attacks, plants develop different mechanismsof defence, in both direct (physical and chemical) and indirect ways (attractive volatiles toentomophagous beneficials). Plants are then able to express traits that facilitate "top-down"control of pests by attracting herbivore predators. Here we investigate the indirect defencemechanism of potato plants by analyzing the volatile patterns of both healthy and aphidinfested plants. Important changes in the emitted terpene pattern by the Myzus persicaeinfested host plant were observed. Using Solid Phase MicroExtraction (SPME) and GC-MS,the (E)-β-farnesene (EBF) appeared to be emitted by aphid-infested potato and not byhealthy plants. To assess the infochemical role of these volatile releases after aphid damageon the aphidophagous predators Episyrphus balteatus, the hoverfly foraging behavior wasassessed using the Observer 5.0 software (Noldus, Wageningen, The Netherlands). Aphidfree potato plants were also used as a control volatile source in the predator behavioral study.While aphid-infested plants induced efficient searching and acceptation behaviors leadingto egg-laying, no kairomonal effect of healthy potato plants was observed, leading to longerimmobility durations and shorter searching periods in the net cage. High oviposition rate ofE. balteatus was observed when aphid-infested potato was used (mean of 48.9 eggs perlaying and per female). On the other hand, no egg was produced by the hoverfly on healthyaphid-free plants. The E. balteatus foraging and reproductive behaviors according to thevolatile emission from aphid-infested plants are discussed in relation to the potential use ofactive infochemical molecules in integrated aphid pest management.

  7. Priming of anti-herbivore defence in Nicotiana attenuata by insect oviposition: herbivore-specific effects.

    Science.gov (United States)

    Bandoly, Michele; Grichnik, Roland; Hilker, Monika; Steppuhn, Anke

    2016-04-01

    Oviposition by Spodoptera exigua on Nicotiana attenuata primes plant defence against its larvae that consequently suffer reduced performance. To reveal whether this is a general response of tobacco to insect oviposition or species-specific, we investigated whether also Manduca sexta oviposition primes N. attenuata's anti-herbivore defence. The plant response to M. sexta and S. exigua oviposition overlapped in the egg-primed feeding-induced production of the phenylpropanoid caffeoylputrescine. While M. sexta larvae were unaffected in their performance, they showed a novel response to the oviposition-mediated plant changes: a reduced antimicrobial activity in their haemolymph. In a cross-resistance experiment, S. exigua larvae suffered reduced performance on M. sexta-oviposited plants like they did on S. exigua-oviposited plants. The M. sexta oviposition-mediated plant effects on the S. exigua larval performance and on M. sexta larval immunity required expression of the NaMyb8 transcription factor that is governing biosynthesis of phenylpropanoids such as caffeoylputrescine. Thus, NaMyb8-dependent defence traits mediate the effects that oviposition by both lepidopteran species exerts on the plant's anti-herbivore defence. These results suggest that oviposition by lepidopteran species on N. attenuata leaves may generally prime the feeding-induced production of certain plant defence compounds but that different herbivore species show different susceptibility to egg-primed plant effects. PMID:26566692

  8. Stylet penetration activities by aphids

    NARCIS (Netherlands)

    Tjallingii, W.F.

    1985-01-01

    The composition of stylet penetration behaviour in aphids and its possible role in food-plant selection is the subject of these studies. Evidence is presented that the labium is devoid of external chemoreceptors (Chapter 1). In addition to other morphological data (Wensler & Filshie, 1969; Wensler,

  9. Infestation of transgenic powdery mildew-resistant wheat by naturally occurring insect herbivores under different environmental conditions.

    Directory of Open Access Journals (Sweden)

    Fernando Álvarez-Alfageme

    Full Text Available A concern associated with the growing of genetically modified (GM crops is that they could adversely affect non-target organisms. We assessed the impact of several transgenic powdery mildew-resistant spring wheat lines on insect herbivores. The GM lines carried either the Pm3b gene from hexaploid wheat, which confers race-specific resistance to powdery mildew, or the less specific anti-fungal barley seed chitinase and β-1,3-glucanase. In addition to the non-transformed control lines, several conventional spring wheat varieties and barley and triticale were included for comparison. During two consecutive growing seasons, powdery mildew infection and the abundance of and damage by naturally occurring herbivores were estimated under semi-field conditions in a convertible glasshouse and in the field. Mildew was reduced on the Pm3b-transgenic lines but not on the chitinase/glucanase-expressing lines. Abundance of aphids was negatively correlated with powdery mildew in the convertible glasshouse, with Pm3b wheat plants hosting significantly more aphids than their mildew-susceptible controls. In contrast, aphid densities did not differ between GM plants and their non-transformed controls in the field, probably because of low mildew and aphid pressure at this location. Likewise, the GM wheat lines did not affect the abundance of or damage by the herbivores Oulema melanopus (L. and Chlorops pumilionis Bjerk. Although a previous study has revealed that some of the GM wheat lines show pleiotropic effects under field conditions, their effect on herbivorous insects appears to be low.

  10. Evidence for the establishment of aphid-eubacterium endosymbiosis in an ancestor of four aphid families.

    OpenAIRE

    Munson, M. A.; Baumann, P.; Clark, M A; Baumann, L; Moran, N A; Voegtlin, D J; Campbell, B C

    1991-01-01

    Aphids (superfamily Aphidoidea) contain eubacterial endosymbionts localized within specialized cells (mycetocytes). The endosymbionts are essential for the survival of the aphid hosts. Sequence analyses of the 16S rRNAs from endosymbionts of 11 aphid species from seven tribes and four families have indicated that the endosymbionts are monophyletic. Furthermore, phylogenetic relationships within the symbiont clade parallel the relationships of the corresponding aphid hosts. Our findings sugges...

  11. AphidBase: A centralized bioinformatic resource for annotation of the pea aphid genome

    OpenAIRE

    Legeai, Fabrice; Shigenobu, Shuji; Gauthier, Jean-Pierre; Colbourne, John; Rispe, Claude; Collin, Olivier; Richards, Stephen; Wilson, Alex C. C.; Tagu, Denis

    2010-01-01

    AphidBase is a centralized bioinformatic resource that was developed to facilitate community annotation of the pea aphid genome by the International Aphid Genomics Consortium (IAGC). The AphidBase Information System designed to organize and distribute genomic data and annotations for a large international community was constructed using open source software tools from the Generic Model Organism Database (GMOD). The system includes Apollo and GBrowse utilities as well as a wiki, blast search c...

  12. 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

  13. Root Herbivores Drive Changes to Plant Primary Chemistry, but Root Loss Is Mitigated under Elevated Atmospheric CO2

    Science.gov (United States)

    McKenzie, Scott W.; Johnson, Scott N.; Jones, T. Hefin; Ostle, Nick J.; Hails, Rosemary S.; Vanbergen, Adam J.

    2016-01-01

    Above- and belowground herbivory represents a major challenge to crop productivity and sustainable agriculture worldwide. How this threat from multiple herbivore pests will change under anthropogenic climate change, via altered trophic interactions and plant response traits, is key to understanding future crop resistance to herbivory. In this study, we hypothesized that atmospheric carbon enrichment would increase the amount (biomass) and quality (C:N ratio) of crop plant resources for above- and belowground herbivore species. In a controlled environment facility, we conducted a microcosm experiment using the large raspberry aphid (Amphorophora idaei), the root feeding larvae of the vine weevil (Otiorhynchus sulcatus), and the raspberry (Rubus idaeus) host-plant. There were four herbivore treatments (control, aphid only, weevil only and a combination of both herbivores) and an ambient (aCO2) or elevated (eCO2) CO2 treatment (390 versus 650 ± 50 μmol/mol) assigned to two raspberry cultivars (cv Glen Ample or Glen Clova) varying in resistance to aphid herbivory. Contrary to our predictions, eCO2 did not increase crop biomass or the C:N ratio of the plant tissues, nor affect herbivore abundance either directly or via the host-plant. Root herbivory reduced belowground crop biomass under aCO2 but not eCO2, suggesting that crops could tolerate attack in a CO2 enriched environment. Root herbivory also increased the C:N ratio in leaf tissue at eCO2, potentially due to decreased N uptake indicated by lower N concentrations found in the roots. Root herbivory greatly increased root C concentrations under both CO2 treatments. Our findings confirm that responses of crop biomass and biochemistry to climate change need examining within the context of herbivory, as biotic interactions appear as important as direct effects of eCO2 on crop productivity. PMID:27379129

  14. Root Herbivores Drive Changes to Plant Primary Chemistry, but Root Loss Is Mitigated under Elevated Atmospheric CO2.

    Science.gov (United States)

    McKenzie, Scott W; Johnson, Scott N; Jones, T Hefin; Ostle, Nick J; Hails, Rosemary S; Vanbergen, Adam J

    2016-01-01

    Above- and belowground herbivory represents a major challenge to crop productivity and sustainable agriculture worldwide. How this threat from multiple herbivore pests will change under anthropogenic climate change, via altered trophic interactions and plant response traits, is key to understanding future crop resistance to herbivory. In this study, we hypothesized that atmospheric carbon enrichment would increase the amount (biomass) and quality (C:N ratio) of crop plant resources for above- and belowground herbivore species. In a controlled environment facility, we conducted a microcosm experiment using the large raspberry aphid (Amphorophora idaei), the root feeding larvae of the vine weevil (Otiorhynchus sulcatus), and the raspberry (Rubus idaeus) host-plant. There were four herbivore treatments (control, aphid only, weevil only and a combination of both herbivores) and an ambient (aCO2) or elevated (eCO2) CO2 treatment (390 versus 650 ± 50 μmol/mol) assigned to two raspberry cultivars (cv Glen Ample or Glen Clova) varying in resistance to aphid herbivory. Contrary to our predictions, eCO2 did not increase crop biomass or the C:N ratio of the plant tissues, nor affect herbivore abundance either directly or via the host-plant. Root herbivory reduced belowground crop biomass under aCO2 but not eCO2, suggesting that crops could tolerate attack in a CO2 enriched environment. Root herbivory also increased the C:N ratio in leaf tissue at eCO2, potentially due to decreased N uptake indicated by lower N concentrations found in the roots. Root herbivory greatly increased root C concentrations under both CO2 treatments. Our findings confirm that responses of crop biomass and biochemistry to climate change need examining within the context of herbivory, as biotic interactions appear as important as direct effects of eCO2 on crop productivity. PMID:27379129

  15. The tri-trophic interactions hypothesis: interactive effects of host plant quality, diet breadth and natural enemies on herbivores.

    Directory of Open Access Journals (Sweden)

    Kailen A Mooney

    Full Text Available Several influential hypotheses in plant-herbivore and herbivore-predator interactions consider the interactive effects of plant quality, herbivore diet breadth, and predation on herbivore performance. Yet individually and collectively, these hypotheses fail to address the simultaneous influence of all three factors. Here we review existing hypotheses, and propose the tri-trophic interactions (TTI hypothesis to consolidate and integrate their predictions. The TTI hypothesis predicts that dietary specialist herbivores (as compared to generalists should escape predators and be competitively dominant due to faster growth rates, and that such differences should be greater on low quality (as compared to high quality host plants. To provide a preliminary test of these predictions, we conducted an empirical study comparing the effects of plant (Baccharis salicifolia quality and predators between a specialist (Uroleucon macolai and a generalist (Aphis gossypii aphid herbivore. Consistent with predictions, these three factors interactively determine herbivore performance in ways not addressed by existing hypotheses. Compared to the specialist, the generalist was less fecund, competitively inferior, and more sensitive to low plant quality. Correspondingly, predator effects were contingent upon plant quality only for the generalist. Contrary to predictions, predator effects were weaker for the generalist and on low-quality plants, likely due to density-dependent benefits provided to the generalist by mutualist ants. Because the TTI hypothesis predicts the superior performance of specialists, mutualist ants may be critical to A. gossypii persistence under competition from U. macolai. In summary, the integrative nature of the TTI hypothesis offers novel insight into the determinants of plant-herbivore and herbivore-predator interactions and the coexistence of specialist and generalist herbivores.

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

    Directory of Open Access Journals (Sweden)

    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.

  17. The impact of domestication on resistance to two generalist herbivores across 29 independent domestication events.

    Science.gov (United States)

    Turcotte, Martin M; Turley, Nash E; Johnson, Marc T J

    2014-11-01

    The domestication of crops is among the most important innovations in human history. Here, we test the hypothesis that cultivation and artificial selection for increased productivity of crops reduced plant defenses against herbivores. We compared the performance of two economically important generalist herbivores - the leaf-chewing beet armyworm (Spodoptera exigua) and the phloem-feeding green peach aphid (Myzus persicae) - across 29 crop species and their closely related wild relatives. We also measured putative morphological and chemical defensive traits and correlated them with herbivore performance. We show that, on average, domestication significantly reduced resistance to S. exigua, but not M. persicae, and that most independent domestication events did not cause differences in resistance to either herbivore. In addition, we found that multiple plant traits predicted resistance to S. exigua and M. persicae, and that domestication frequently altered the strength and direction of correlations between these traits and herbivore performance. Our results show that domestication can alter plant defenses, but does not cause strong allocation tradeoffs as predicted by plant defense theory. These results have important implications for understanding the evolutionary ecology of species interactions and for the search for potential resistance traits to be targeted in crop breeding.

  18. The impact of domestication on resistance to two generalist herbivores across 29 independent domestication events.

    Science.gov (United States)

    Turcotte, Martin M; Turley, Nash E; Johnson, Marc T J

    2014-11-01

    The domestication of crops is among the most important innovations in human history. Here, we test the hypothesis that cultivation and artificial selection for increased productivity of crops reduced plant defenses against herbivores. We compared the performance of two economically important generalist herbivores - the leaf-chewing beet armyworm (Spodoptera exigua) and the phloem-feeding green peach aphid (Myzus persicae) - across 29 crop species and their closely related wild relatives. We also measured putative morphological and chemical defensive traits and correlated them with herbivore performance. We show that, on average, domestication significantly reduced resistance to S. exigua, but not M. persicae, and that most independent domestication events did not cause differences in resistance to either herbivore. In addition, we found that multiple plant traits predicted resistance to S. exigua and M. persicae, and that domestication frequently altered the strength and direction of correlations between these traits and herbivore performance. Our results show that domestication can alter plant defenses, but does not cause strong allocation tradeoffs as predicted by plant defense theory. These results have important implications for understanding the evolutionary ecology of species interactions and for the search for potential resistance traits to be targeted in crop breeding. PMID:25039644

  19. Relative importance of biotic and abiotic soil components to plant growth and insect herbivore population dynamics.

    Directory of Open Access Journals (Sweden)

    Martijn L Vandegehuchte

    Full Text Available BACKGROUND: Plants are affected by several aspects of the soil, which have the potential to exert cascading effects on the performance of herbivorous insects. The effects of biotic and abiotic soil characteristics have however mostly been investigated in isolation, leaving their relative importance largely unexplored. Such is the case for the dune grass Ammophila, whose decline under decreasing sand accretion is argued to be caused by either biotic or abiotic soil properties. METHODOLOGY/PRINCIPAL FINDINGS: By manipulating dune soils from three different regions, we decoupled the contributions of region, the abiotic and biotic soil component to the variation in characteristics of Ammophila arenaria seedlings and Schizaphis rufula aphid populations. Root mass fraction and total dry biomass of plants were affected by soil biota, although the latter effect was not consistent across regions. None of the measured plant properties were significantly affected by the abiotic soil component. Aphid population characteristics all differed between regions, irrespective of whether soil biota were present or absent. Hence these effects were due to differences in abiotic soil properties between regions. Although several chemical properties of the soil mixtures were measured, none of these were consistent with results for plant or aphid traits. CONCLUSIONS/SIGNIFICANCE: Plants were affected more strongly by soil biota than by abiotic soil properties, whereas the opposite was true for aphids. Our results thus demonstrate that the relative importance of the abiotic and biotic component of soils can differ for plants and their herbivores. The fact that not all effects of soil properties could be detected across regions moreover emphasizes the need for spatial replication in order to make sound conclusions about the generality of aboveground-belowground interactions.

  20. Transparency Master: The Annual Aphid Cycle.

    Science.gov (United States)

    Sessions, Mary Lynne

    1983-01-01

    Aphids, often referred to as plant lice, can be found in great numbers on stems, leaves, and flowers of many plants. In many cases these organisms are potentially harmful to their plant hosts. Provided is a description of the annual life cycle of the aphid and an accompanying transparency master. (Author/JN)

  1. Plant defense against insect herbivores

    DEFF Research Database (Denmark)

    Fürstenberg-Hägg, Joel; Zagrobelny, Mika; Bak, Søren

    2013-01-01

    , defense compounds. These bioactive specialized plant defense compounds may repel or intoxicate insects, while defense proteins often interfere with their digestion. Volatiles are released upon herbivory to repel herbivores, attract predators or for communication between leaves or plants, and to induce...... defense responses. Plants also apply morphological features like waxes, trichomes and latices to make the feeding more difficult for the insects. Extrafloral nectar, food bodies and nesting or refuge sites are produced to accommodate and feed the predators of the herbivores. Meanwhile, herbivorous insects...

  2. Caterpillar mimicry by plant galls as a visual defense against herbivores.

    Science.gov (United States)

    Yamazaki, Kazuo

    2016-09-01

    Plant galls, induced by arthropods and various other organisms have an intimate relationship with host plants, and gall-inducers have limited mobility. In addition to their own photosynthesis, galls are resource sinks rich with nutrients, with neighboring plant organs commonly serving as external photosynthate sources. Galls, if not well defended, may therefore be attractive food sources for herbivores. Galls produced by some aphids, jumping plant lice, thrips, and gall midges in Japan, Palearctic region and in the Middle East visually resemble lepidopteran caterpillars. I propose that such visual resemblance may reduce herbivory of galls and surrounding plant tissues, resulting in an increase in galler survival due to reduced gall damage and in enhanced galler growth due to improved nutrient inflow to the galls, when herbivores avoid colonizing or consuming plant parts that look as if they have been occupied by other herbivores. Potential predators and parasitoids of caterpillars may be attracted to the caterpillar-like galls and then attack real caterpillars and other invertebrate herbivores, which would also be beneficial for both gallers and their hosts. PMID:27220745

  3. Glucosinolates from Host Plants Influence Growth of the Parasitic Plant Cuscuta gronovii and Its Susceptibility to Aphid Feeding.

    Science.gov (United States)

    Smith, Jason D; Woldemariam, Melkamu G; Mescher, Mark C; Jander, Georg; De Moraes, Consuelo M

    2016-09-01

    Parasitic plants acquire diverse secondary metabolites from their hosts, including defense compounds that target insect herbivores. However, the ecological implications of this phenomenon, including the potential enhancement of parasite defenses, remain largely unexplored. We studied the translocation of glucosinolates from the brassicaceous host plant Arabidopsis (Arabidopsis thaliana) into parasitic dodder vines (Convolvulaceae; Cuscuta gronovii) and its effects on the parasite itself and on dodder-aphid interactions. Aliphatic and indole glucosinolates reached concentrations in parasite tissues higher than those observed in corresponding host tissues. Dodder growth was enhanced on cyp79B2 cyp79B3 hosts (without indole glucosinolates) but inhibited on atr1D hosts (with elevated indole glucosinolates) relative to wild-type hosts, which responded to parasitism with localized elevation of indole and aliphatic glucosinolates. These findings implicate indole glucosinolates in defense against parasitic plants. Rates of settling and survival on dodder vines by pea aphids (Acyrthosiphon pisum) were reduced significantly when dodder parasitized glucosinolate-producing hosts (wild type and atr1D) compared with glucosinolate-free hosts (cyp79B2 cyp79B3 myb28 myb29). However, settling and survival of green peach aphids (Myzus persicae) were not affected. M. persicae population growth was actually reduced on dodder parasitizing glucosinolate-free hosts compared with wild-type or atr1D hosts, even though stems of the former contain less glucosinolates and more amino acids. Strikingly, this effect was reversed when the aphids fed directly upon Arabidopsis, which indicates an interactive effect of parasite and host genotype on M. persicae that stems from host effects on dodder. Thus, our findings indicate that glucosinolates may have both direct and indirect effects on dodder-feeding herbivores. PMID:27482077

  4. Ethylene Contributes to maize insect resistance1-Mediated Maize Defense against the Phloem Sap-Sucking Corn Leaf Aphid.

    Science.gov (United States)

    Louis, Joe; Basu, Saumik; Varsani, Suresh; Castano-Duque, Lina; Jiang, Victoria; Williams, W Paul; Felton, Gary W; Luthe, Dawn S

    2015-09-01

    Signaling networks among multiple phytohormones fine-tune plant defense responses to insect herbivore attack. Previously, it was reported that the synergistic combination of ethylene (ET) and jasmonic acid (JA) was required for accumulation of the maize insect resistance1 (mir1) gene product, a cysteine (Cys) proteinase that is a key defensive protein against chewing insect pests in maize (Zea mays). However, this study suggests that mir1-mediated resistance to corn leaf aphid (CLA; Rhopalosiphum maidis), a phloem sap-sucking insect pest, is independent of JA but regulated by the ET-signaling pathway. Feeding by CLA triggers the rapid accumulation of mir1 transcripts in the resistant maize genotype, Mp708. Furthermore, Mp708 provided elevated levels of antibiosis (limits aphid population)- and antixenosis (deters aphid settling)-mediated resistance to CLA compared with B73 and Tx601 maize susceptible inbred lines. Synthetic diet aphid feeding trial bioassays with recombinant Mir1-Cys Protease demonstrates that Mir1-Cys Protease provides direct toxicity to CLA. Furthermore, foliar feeding by CLA rapidly sends defensive signal(s) to the roots that trigger belowground accumulation of the mir1, signifying a potential role of long-distance signaling in maize defense against the phloem-feeding insects. Collectively, our data indicate that ET-regulated mir1 transcript accumulation, uncoupled from JA, contributed to heightened resistance to CLA in maize. In addition, our results underscore the significance of ET acting as a central node in regulating mir1 expression to different feeding guilds of insect herbivores. PMID:26253737

  5. Categorizing sugarcane cultivar resistance to the sugarcane aphid and yellow sugarcane aphid (Hemiptera: Aphididae).

    Science.gov (United States)

    Akbar, W; Showler, A T; Reagan, T E; White, W H

    2010-08-01

    Sugarcane (Saccharum spp.) in Louisiana is colonized by two aphid species, the sugarcane aphid, Melanaphis sacchari (Zehntner), and the yellow sugarcane aphid, Sipha flava (Forbes) (Hemiptera: Aphididae). The main problem associated with M. sacchari is transmission of sugarcane yellow leaf virus, a casual agent of yellow leaf disease whose absence has been added to certification standards for micropropagated sugarcane in Louisiana. Greenhouse studies were conducted to categorize dominant commercial sugarcane cultivars for their ability to tolerate aphid injury and to express antixenotic or antibiotic effects on both aphid species. Antixenosis tests showed no preference among cultivars by either aphid species. Loss of chlorophyll content in tolerance tests also did not show differences among cultivars for both aphid species. However, antibiosis tests revealed that life history parameters such as the duration of the reproductive period and fecundity of both aphid species were negatively affected on 'HoCP 91-555' compared with 'L 97-128'. Estimation of demographic statistics indicated that both aphid species exhibited a significantly lower intrinsic rate of increase (1.8-2.8-fold) and longer doubling time (1.7-3.1-fold) on HoCP 91-555 relative to L 97-128. From these tests, cultivars in the current study can be ranked from most to the least susceptible as L 97-128 > 'LCP 85-384' > 'HoCP 96-540' > 'Ho 95-988' > HoCP 91-555 for M. sacchari and L 97-128 > LCP 85-384 > HoCP 91-555 for S. flava. Therefore, antibiosis is an important category of resistance in sugarcane to both aphid species, and HoCP 91-555 might provide useful germplasm for developing aphid resistant cultivars. PMID:20857758

  6. Characterisation of aphid myrosinase and degradation studies of glucosinolates.

    Science.gov (United States)

    Francis, Frédéric; Lognay, Georges; Wathelet, Jean-Paul; Haubruge, Eric

    2002-08-01

    Myrosinase from Brevicoryne brassicae was purified by ammonium sulfate fractionation, dialysis, and chromatography on a DEAE column. The chromatography yielded a single peak and a 115.6-fold purification. Further FPLC gel filtration gave a single peak at 120 kDa. Denaturing SDS/PAGE of the protein revealed a single band at 60 kDa, indicating that the native B. brassicae myrosinase is a dimer. Kinetic parameters towards 8 glucosinolates were calculated. Strong differences of V(max) and K(m) were observed depending on the substrate. Degradation products of each glucosinolate were identified and quantified by GC-MS and GLC-FID, respectively. Using both crude aphid homogenates and purified myrosinase, two unique hydroxyglucosinolates, 3-butenyl- and benzyl-isothiocyanates were identified from progoitrin ((2S)-2-hydroxybut-3-enyl-glucosinolate) and sinalbin (4-hydroxybenzyl-glucosinolate) degradation respectively. Addition of ascorbic acid to the reaction mixtures containing sinalbin and progoitrin caused the production of hydroxylated degradation products usually associated with plant myrosinase metabolisation. The occurrence of the myrosinase system in B. brassicae is discussed in terms of similar allelochemical adaptation between the herbivore and its host plant. PMID:12125058

  7. Reciprocal responses in the interaction between Arabidopsis and the cell-content-feeding chelicerate herbivore spider mite.

    Science.gov (United States)

    Zhurov, Vladimir; Navarro, Marie; Bruinsma, Kristie A; Arbona, Vicent; Santamaria, M Estrella; Cazaux, Marc; Wybouw, Nicky; Osborne, Edward J; Ens, Cherise; Rioja, Cristina; Vermeirssen, Vanessa; Rubio-Somoza, Ignacio; Krishna, Priti; Diaz, Isabel; Schmid, Markus; Gómez-Cadenas, Aurelio; Van de Peer, Yves; Grbic, Miodrag; Clark, Richard M; Van Leeuwen, Thomas; Grbic, Vojislava

    2014-01-01

    Most molecular-genetic studies of plant defense responses to arthropod herbivores have focused on insects. However, plant-feeding mites are also pests of diverse plants, and mites induce different patterns of damage to plant tissues than do well-studied insects (e.g. lepidopteran larvae or aphids). The two-spotted spider mite (Tetranychus urticae) is among the most significant mite pests in agriculture, feeding on a staggering number of plant hosts. To understand the interactions between spider mite and a plant at the molecular level, we examined reciprocal genome-wide responses of mites and its host Arabidopsis (Arabidopsis thaliana). Despite differences in feeding guilds, we found that transcriptional responses of Arabidopsis to mite herbivory resembled those observed for lepidopteran herbivores. Mutant analysis of induced plant defense pathways showed functionally that only a subset of induced programs, including jasmonic acid signaling and biosynthesis of indole glucosinolates, are central to Arabidopsis's defense to mite herbivory. On the herbivore side, indole glucosinolates dramatically increased mite mortality and development times. We identified an indole glucosinolate dose-dependent increase in the number of differentially expressed mite genes belonging to pathways associated with detoxification of xenobiotics. This demonstrates that spider mite is sensitive to Arabidopsis defenses that have also been associated with the deterrence of insect herbivores that are very distantly related to chelicerates. Our findings provide molecular insights into the nature of, and response to, herbivory for a representative of a major class of arthropod herbivores.

  8. Seasonal Abundance of Aphids and Aphidophagous Insects in Pecan

    OpenAIRE

    Ghulam Abbas; Dutcher, James D.; Haider Karar

    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 ove...

  9. Community-wide impact of an exotic aphid on introduced tall goldenrod

    OpenAIRE

    Ando, Yoshino; Utsumi, Shunsuke; Ohgushi, Takayuki

    2011-01-01

    1. The aphid Uroleucon nigrotuberculatum Olive, which is specialised to the tall goldenrod, Solidago altissima L., in its native range, has become a dominant species on the introduced tall goldenrod in Japan. How this exotic aphid influenced arthropod communities on the introduced tall goldenrod in aphid-present (spring) and aphid-absent (autumn) seasons was examined, using an aphid removal experiment. 2. In spring, aphid presence increased ant abundance because aphid honeydew attracted fo...

  10. 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

  11. Aphid-AutoEPG software for analysing electrically monitored feeding behaviour of aphids

    Directory of Open Access Journals (Sweden)

    Toni Prüfer

    2014-06-01

    Full Text Available Aphid-AutoEPG is a new software program, developed to acquire and automatically analyse electrical penetration graph (EPG signals used for monitoring plant penetration by aphids. Characteristically EPG signals include waveforms that allow one to study the effects of plants on the acquisition and transmission of viruses, plant protection substances on pests and identify the location of resistance in plants to aphids. The success of electrical monitoring arises from the fact that different species of aphids generate similar EPG patterns. But the visual analysis of EPG waveforms in recorded signals is very time consuming, which has greatly hampered the wider application of EPG technology. To overcome this Aphid-AutoEPG software was developed, which has been extensively tested using data files for several different species of aphids, M. persicae, A. frangulae gossypii, M. albifrons, S. avenae, B. brassicae and N. ribis-nigri. The results have also been compared with visual analyses using Stylet+ software. When used in combination with the user friendly correction options Aphid-AutoEPG is not only easy to use but can also result in a considerable saving in terms of time.

  12. Influences of elevated CO2 and pest damage on the allocation of plant defense compounds in Bt-transgenic cotton and enzymatic activity of cotton aphid

    Institute of Scientific and Technical Information of China (English)

    Gang Wu; Fa-Jun Chen; Neng-Wen Xiao; Feng Ge

    2011-01-01

    Plant allocation to defensive compounds by elevated CO2-grown nontransgenic and transgenic Bt cotton in response to infestation by cotton aphid,Aphis gossypii (Glover) in open-top chambers under elevated CO2 were studied.The results showed that significantly lower foliar nitrogen concentration and Bt toxin protein occurred in transgenic Bt cotton with and without cotton aphid infestation under elevated CO2.However,significantly higher carbon/nitrogen ratio,condensed tannin and gossypol were observed in transgenic Bt cotton "GK-12" and non-transgenic Bt cotton ‘Simian-3' under elevated CO2.The CO2 level and cotton variety significantly influenced the foliar nitrogen,condensed tannin and gossypol concentrations in the plant leaves after feeding by A.gossypii.The interaction between CO2 level × infestation time (24 h,48 h and 72 h)showed a significant increase in cotton condensed tannin concentrations,while the interaction between CO2 level × cotton variety significantly decreased the true choline esterase (TChE) concentration in the body ofA.gossypi.This study exemplified the complexities of predicting how transgenic and non-transgenic plants will allocate defensive compounds in response to herbivorous insects under differing climatic conditions.Plant defensive compound allocation patterns and aphid enzyme changes observed in this study appear to be broadly applicable across a range of plant and herbivorous insect interactions as CO2 atmosphere rises.

  13. Increased resistance to a generalist herbivore in a salinity-stressed non-halophytic plant.

    Science.gov (United States)

    Renault, Sylvie; Wolfe, Scott; Markham, John; Avila-Sakar, Germán

    2016-01-01

    Plants often grow under the combined stress of several factors. Salinity and herbivory, separately, can severely hinder plant growth and reproduction, but the combined effects of both factors are still not clearly understood. Salinity is known to reduce plant tissue nitrogen content and growth rates. Since herbivores prefer tissues with high N content, and biochemical pathways leading to resistance are commonly elicited by salt-stress, we hypothesized that plants growing in saline conditions would have enhanced resistance against herbivores. The non-halophyte, Brassica juncea, and the generalist herbivore Trichoplusia ni were used to test the prediction that plants subjected to salinity stress would be both more resistant and more tolerant to herbivory than those growing without salt stress. Plants were grown under different NaCl levels, and either exposed to herbivores and followed by removal of half of their leaves, or left intact. Plants were left to grow and reproduce until senescence. Tissue quality was assessed, seeds were counted and biomass of different organs measured. Plants exposed to salinity grew less, had reduced tissue nitrogen, protein and chlorophyll content, although proline levels increased. Specific leaf area, leaf water content, transpiration and root:shoot ratio remained unaffected. Plants growing under saline condition had greater constitutive resistance than unstressed plants. However, induced resistance and tolerance were not affected by salinity. These results support the hypothesis that plants growing under salt-stress are better defended against herbivores, although in B. juncea this may be mostly through resistance, and less through tolerance. PMID:27169610

  14. 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. PMID:25197882

  15. Pan trapping soybean aphids (Hemiptera: Aphididae) using attractants.

    Science.gov (United States)

    Behrens, Nicholas S; Zhu, Junwei; Coats, Joel R

    2012-06-01

    Since its introduction into the United States in the past 10 yr, soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), has been a damaging pest to soybean, Glycine max (L.) Merrill. During 2008 and 2009, fields in central and north central Iowa experienced pockets of high soybean aphid populations. Electroantennograms have shown that soybean aphid alatae are capable of detecting host plant volatiles and sex pheromones. Here, we evaluated baited pan traps as a potential soybean aphid attractant. Yellow pan traps were placed in soybean fields after planting along with lures that contained plant volatiles and sex pheromones in 2008 or sex pheromones only in 2009. Pan trap contents were collected weekly, and plant counts also were conducted. Aphids were identified, and soybean aphids were counted to determine whether one chemical lure was more attractive to spring migrants than other lures. In both years, soybean aphids collected in pan traps with lures were not significantly different from the other products tested. PMID:22812127

  16. Symbiotic bacterium modifies aphid body color.

    Science.gov (United States)

    Tsuchida, Tsutomu; Koga, Ryuichi; Horikawa, Mitsuyo; Tsunoda, Tetsuto; Maoka, Takashi; Matsumoto, Shogo; Simon, Jean-Christophe; Fukatsu, Takema

    2010-11-19

    Color variation within populations of the pea aphid influences relative susceptibility to predators and parasites. We have discovered that infection with a facultative endosymbiont of the genus Rickettsiella changes the insects' body color from red to green in natural populations. Approximately 8% of pea aphids collected in Western Europe carried the Rickettsiella infection. The infection increased amounts of blue-green polycyclic quinones, whereas it had less of an effect on yellow-red carotenoid pigments. The effect of the endosymbiont on body color is expected to influence prey-predator interactions, as well as interactions with other endosymbionts. PMID:21097935

  17. Light, nutrients, and herbivore growth in oligotrophic streams

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Walter R [ORNL; Smith, John G [ORNL; Stewart, Arthur J [ORNL

    2010-02-01

    The light : nutrient hypothesis posits that herbivore growth is increasingly constrained by low food quality as the ratio of light to nutrients increases in aquatic ecosystems. We tested predictions of this hypothesis by examining the effects of large seasonal cycles in light and nutrients on the mineral content of periphyton and the growth rate of a dominant herbivore (the snail Elimia clavaeformis) in two oligotrophic streams. Streambed irradiances in White Oak Creek and Walker Branch (eastern Tennessee, USA) varied dramatically on a seasonal basis due to leaf phenology in the surrounding deciduous forests and seasonal changes in sun angle. Concentrations of dissolved nutrients varied inversely with light, causing light : nitrate and light : phosphate to range almost 100-fold over the course of any individual year. Periphyton nitrogen and phosphorus concentrations were much lower than the concentrations of these elements in snails, and they bottomed out in early spring when streambed irradiances were highest. Snail growth, however, peaked in early spring when light:nutrient ratios were highest and periphyton nutrient concentrations were lowest, Growth was linearly related to primary production (accounting for up to 85% of growth variance in individual years), which in turn was driven by seasonal variation in light. Conceptual models of herbivore growth indicate that growth should initially increase as increasing light levels stimulate primary production, but then level off, and then decrease as the negative effects of decreasing algal nutrient content override the positive effects of increased food production. Our results showed no evidence of an inflection point where increasing ratios of light to nutrients negatively affected growth. Snail growth in these intensively grazed streams is probably unaffected by periphyton nutrient content because exploitative competition for food reduces growth rates to levels where the demand for nitrogen and phosphorus is small

  18. Genotypic variation in yellow autumn leaf colours explains aphid load in silver birch.

    Science.gov (United States)

    Sinkkonen, Aki; Somerkoski, Eeva; Paaso, Ulla; Holopainen, Jarmo K; Rousi, Matti; Mikola, Juha

    2012-07-01

    • It has been suggested that autumn-migrating insects drive the evolution of autumn leaf colours. However, evidence of genetic variation in autumn leaf colours in natural tree populations and the link between the genetic variation and herbivore abundances has been lacking. • Here, we measured the size of the whole aphid community and the development of green-yellow leaf colours in six replicate trees of 19 silver birch (Betula pendula) genotypes at the beginning, in the middle and at the end of autumn colouration. We also calculated the difference between green leaf and leaf litter nitrogen (N) and estimated the changes in phloem sap N loading. • Autumn leaf colouration had significant genetic variation. During the last survey, genotypes that expressed the strongest leaf reflectance 2-4 wk earlier had an abundance of egg-laying Euceraphis betulae females. Surprisingly, the aphid community size during the first surveys explained N loss by the litter of different birch genotypes. • Our results are the first evidence at the tree intrapopulation genotypic level that autumn-migrating pests have the potential to drive the evolution of autumn leaf colours. They also stress the importance of recognizing the role of late-season tree-insect interactions in the evolution of herbivory resistance. PMID:22548444

  19. National Plant Diagnostic Network, Taxonomic training videos: Introduction to Aphids - Part 1

    Science.gov (United States)

    Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides visual instruction on important subject areas for aphid examination and identification. Aphid topics such as classification, morphology, plant disease transmission, and references are discussed. This dis...

  20. Locomotion in Stroke Subjects: Interactions between Unaffected and Affected Sides

    Science.gov (United States)

    Kloter, Evelyne; Wirz, Markus; Dietz, Volker

    2011-01-01

    The aim of this study was to evaluate the sensorimotor interactions between unaffected and affected sides of post-stroke subjects during locomotion. In healthy subjects, stimulation of the tibial nerve during the mid-stance phase is followed by electromyography responses not only in the ipsilateral tibialis anterior, but also in the proximal arm…

  1. Infestation and natural parasitism of aphids in single and mixed pastures of black oats and ryegrass

    OpenAIRE

    Vinícius Soares Sturza; Sônia Poncio; Aline Bosak dos Santos; Marcelo Lopes-da-Silva

    2012-01-01

    Some species of aphids are major pests on cereal crops and grass pastures. Usually these pests are not adequately controlled in pasture lands that become sources of aphid infestations to cereal crops. The dynamics of aphids and the incidence of natural enemies are less known in pasture systems than in cereal fields. The objective of this work was to assess the aphid infestation and natural aphid parasitism in different pasture composition. Three hypotheses were tested: 1- the aphid species co...

  2. Effects of quantitative variation in allelochemicals in Plantago lanceolata on development of a generalist and a specialist herbivore and their endoparasitoids.

    Science.gov (United States)

    Harvey, Jeffrey A; van Nouhuys, Saskya; Biere, Arjen

    2005-02-01

    Studies in crop species show that the effect of plant allelochemicals is not necessarily restricted to herbivores, but can extend to (positive as well as negative) effects on performance at higher trophic levels, including the predators and parasitoids of herbivores. We examined how quantitative variation in allelochemicals (iridoid glycosides) in ribwort plantain, Plantago lanceolata, affects the development of a specialist and a generalist herbivore and their respective specialist and generalist endoparasitoids. Plants were grown from two selection lines that differed ca. 5-fold in the concentration of leaf iridoid glycosides. Development time of the specialist herbivore, Melitaea cinxia, and its solitary endoparasitoid, Hyposoter horticola, proceeded most rapidly when reared on the high iridoid line, whereas pupal mass in M. cinxia and adult mass in H. horticola were unaffected by plant line. Cotesia melitaearum, a gregarious endoparasitoid of M. cinxia, performed equally well on hosts feeding on the two lines of P. lanceolata. In contrast, the pupal mass of the generalist herbivore, Spodoptera exigua, and the emerging adult mass of its solitary endoparasitoid, C. marginiventris, were significantly lower when reared on the high line, whereas development time was unaffected. The results are discussed with regards to (1) differences between specialist and generalist herbivores and their natural enemies to quantitative variation in plant secondary chemistry, and (2) potentially differing selection pressures on plant defense. PMID:15856784

  3. Birds exploit herbivore-induced plant volatiles to locate herbivorous prey

    NARCIS (Netherlands)

    Amo, L.; Jansen, J.J.; Dam, van N.M.; Dicke, M.; Visser, M.E.

    2013-01-01

    Arthropod herbivory induces plant volatiles that can be used by natural enemies of the herbivores to find their prey. This has been studied mainly for arthropods that prey upon or parasitise herbivorous arthropods but rarely for insectivorous birds, one of the main groups of predators of herbivorous

  4. Molecular sabotage of plant defense by aphid saliva

    OpenAIRE

    Will, T; Tjallingii, W.F.; Thönnessen, A.; Bel,, T.

    2007-01-01

    Aphids, which constitute one of the most important groups of agricultural pests, ingest nutrients from sieve tubes, the photoassimilate transport conduits in plants. Aphids are able to successfully puncture sieve tubes with their piercing mouthparts (stylets) and ingest phloem sap without eliciting the sieve tubes' normal occlusion response to injury. Occlusion mechanisms are calcium-triggered and may be prevented by chemical constituents in aphid saliva injected into sieve tubes before and d...

  5. Life-history strategies affect aphid preference for yellowing leaves

    OpenAIRE

    Holopainen, Jarmo K.; Semiz, Gürkan; Blande, James D

    2009-01-01

    According to the nutrient-translocation hypothesis, yellowing tree leaves are colonized by aphids at the end of the growing season owing to improved availability of nutrients in the phloem sap after chlorophyll degradation. We measured aphid densities on potted Betula pendula seedlings in a field site where a small proportion of foliage rapidly turned yellow before normal autumn coloration as a consequence of root anoxia. The number of adults and nymphs of the birch-feeding specialist aphids ...

  6. Effects of herbivores on grassland plant diversity

    NARCIS (Netherlands)

    Olff, Han; Ritchie, Mark E.

    1998-01-01

    The role of herbivores in controlling plant species richness is a critical issue in the conservation and management of grassland biodiversity. Numerous field experiments in grassland plant communities show that herbivores often, but not always, increase plant diversity. Recent work suggests that the

  7. Effects of herbivores on grassland plant diversity.

    NARCIS (Netherlands)

    Olff, H.; Ritchie, M.E.

    1998-01-01

    The role of herbivores in controlling plant species richness is a critical issue in the conservation and management of grassland biodiversity. Numerous field experiments in grassland plant communities show that herbivores often, but not always, increase plant diversity. Recent work suggests that the

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

    NARCIS (Netherlands)

    Hol, W.H.G.; Raaijmakers, C.E.; Mons, Ilse; Meyer, Katrin M.; van Dam, N.M.

    2016-01-01

    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

  9. Detection is unaffected by the deployment of focal attention

    Directory of Open Access Journals (Sweden)

    Jeff eMoher

    2013-05-01

    Full Text Available There has been much debate regarding how much information humans can extract from their environment without the use of limited attentional resources. In a recent study, Theeuwes, Van der Burg, and Belopolsky (2008 argued that even detection of simple feature targets is not possible without selection by focal attention. Supporting this claim, they found response time benefits in a simple feature (color detection task when a target letter’s identity was repeated on consecutive trials, suggesting that the letter was selected by focal attention and identified prior to detection. This intertrial repetition benefit remained even when observers were required to simultaneously identify a central digit. However, we found that intertrial repetition benefits disappeared when a simple color target was presented among a heterogeneously (rather than homogeneously colored set of distractors, thus reducing its bottom-up salience. Still, detection performance remained high. Thus, detection performance was unaffected by whether a letter was focally attended and identified prior to detection or not. Intertrial identity repetition benefits also disappeared when observers were required to perform a simultaneous, attention-demanding central task (Experiment 2, or when unfamiliar Chinese characters were used (Experiment 3. Together, these results suggest that while shifts of focal attention can be affected by target salience, by the availability of excess cognitive resources, and by target familiarity, detection performance itself is unaffected by these manipulations and is thus unaffected by the deployment of focal attention.

  10. Taxonomy Icon Data: pea aphid [Taxonomy Icon

    Lifescience Database Archive (English)

    Full Text Available pea aphid Acyrthosiphon pisum Arthropoda Acyrthosiphon_pisum_L.png Acyrthosiphon_pisum_NL.png Acyrthosiph...on_pisum_S.png Acyrthosiphon_pisum_NS.png http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Acyrthosiph...on+pisum&t=L http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Acyrthosiphon+pisum&t=NL http:...//biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Acyrthosiphon+pisum&t=S http://biosciencedbc.jp/taxonomy_icon/icon.cgi?i=Acyrthosiphon+pisum&t=NS ...

  11. Crop association to improve aphid biological control

    OpenAIRE

    Chevalier Mendes Lopes, Thomas; Bosquée, Emilie; Bodson, Bernard; Francis, Frédéric

    2014-01-01

    This research focused on the development of sustainable alternative methods to control aphids, giving special emphasis on cultural practices and plant management systems. Increasing the diversity within crops may have several beneficial effects on pest control, creating attractive habitats for indigenous beneficial fauna and simultaneously deterring pests (“push-pull” approach). In this field study, two wheat/pea associations (mixed cropping and strip cropping) where compared to monocultures ...

  12. Experimental infection of plants with an herbivore-associated bacterial endosymbiont influences herbivore host selection behavior.

    Directory of Open Access Journals (Sweden)

    Thomas Seth Davis

    Full Text Available Although bacterial endosymbioses are common among phloeophagous herbivores, little is known regarding the effects of symbionts on herbivore host selection and population dynamics. We tested the hypothesis that plant selection and reproductive performance by a phloem-feeding herbivore (potato psyllid, Bactericera cockerelli is mediated by infection of plants with a bacterial endosymbiont. We controlled for the effects of herbivory and endosymbiont infection by exposing potato plants (Solanum tuberosum to psyllids infected with "Candidatus Liberibacter solanacearum" or to uninfected psyllids. We used these treatments as a basis to experimentally test plant volatile emissions, herbivore settling and oviposition preferences, and herbivore population growth. Three important findings emerged: (1 plant volatile profiles differed with respect to both herbivory and herbivory plus endosymbiont infection when compared to undamaged control plants; (2 herbivores initially settled on plants exposed to endosymbiont-infected psyllids but later defected and oviposited primarily on plants exposed only to uninfected psyllids; and (3 plant infection status had little effect on herbivore reproduction, though plant flowering was associated with a 39% reduction in herbivore density on average. Our experiments support the hypothesis that plant infection with endosymbionts alters plant volatile profiles, and infected plants initially recruited herbivores but later repelled them. Also, our findings suggest that the endosymbiont may not place negative selection pressure on its host herbivore in this system, but plant flowering phenology appears correlated with psyllid population performance.

  13. National Plant Diagnostic Network, Taxonomic training videos: Introduction to Aphids - Part 2

    Science.gov (United States)

    Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides visual instruction on important subject areas for aphid regulatory issues. Here the subject of aphids as they relate to disease transmission, biology, identification, and pathways is addressed. Aphid topi...

  14. Herbivore space use influences coral reef recovery.

    Science.gov (United States)

    Eynaud, Yoan; McNamara, Dylan E; Sandin, Stuart A

    2016-06-01

    Herbivores play an important role in marine communities. On coral reefs, the diversity and unique feeding behaviours found within this functional group can have a comparably diverse set of impacts in structuring the benthic community. Here, using a spatially explicit model of herbivore foraging, we explore how the spatial pattern of grazing behaviours impacts the recovery of a reef ecosystem, considering movements at two temporal scales-short term (e.g. daily foraging patterns) and longer term (e.g. monthly movements across the landscape). Model simulations suggest that more spatially constrained herbivores are more effective at conferring recovery capability by providing a favourable environment to coral recruitment and growth. Results also show that the composition of food available to the herbivore community is linked directly to the pattern of space use by herbivores. To date, most studies of variability among the impacts of herbivore species have considered the diversity of feeding modes and mouthparts. Our work provides a complementary view of spatial patterns of foraging, revealing that variation in movement behaviours alone can affect patterns of benthic change, and thus broadens our view of realized links between herbivore diversity and reef recovery. PMID:27429784

  15. Herbivore space use influences coral reef recovery

    Science.gov (United States)

    Eynaud, Yoan; McNamara, Dylan E.; Sandin, Stuart A.

    2016-01-01

    Herbivores play an important role in marine communities. On coral reefs, the diversity and unique feeding behaviours found within this functional group can have a comparably diverse set of impacts in structuring the benthic community. Here, using a spatially explicit model of herbivore foraging, we explore how the spatial pattern of grazing behaviours impacts the recovery of a reef ecosystem, considering movements at two temporal scales—short term (e.g. daily foraging patterns) and longer term (e.g. monthly movements across the landscape). Model simulations suggest that more spatially constrained herbivores are more effective at conferring recovery capability by providing a favourable environment to coral recruitment and growth. Results also show that the composition of food available to the herbivore community is linked directly to the pattern of space use by herbivores. To date, most studies of variability among the impacts of herbivore species have considered the diversity of feeding modes and mouthparts. Our work provides a complementary view of spatial patterns of foraging, revealing that variation in movement behaviours alone can affect patterns of benthic change, and thus broadens our view of realized links between herbivore diversity and reef recovery. PMID:27429784

  16. Molecular sabotage of plant defense by aphid saliva

    NARCIS (Netherlands)

    Will, T.; Tjallingii, W.F.; Thönnessen, A.; Bel, van A.J.E.

    2007-01-01

    Aphids, which constitute one of the most important groups of agricultural pests, ingest nutrients from sieve tubes, the photoassimilate transport conduits in plants. Aphids are able to successfully puncture sieve tubes with their piercing mouthparts (stylets) and ingest phloem sap without eliciting

  17. 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.

  18. 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

  19. Genome-wide association mapping of soybean aphid resistance traits

    Science.gov (United States)

    Soybean aphid is the most damaging insect pest of soybean in the Upper Midwest and is primarily controlled by insecticides. Soybean aphid resistance (i.e., Rag genes) has been documented in some soybean lines at chromosomes 6, 7, 13, and 16, but more sources of resistance are needed. Genome-wide ass...

  20. Breeding for resistance to the sugarcane aphid [Melanaphis sacchari (Zehntner)

    Science.gov (United States)

    The sugarcane aphid [Melanaphis sacchari] (SCA) was first reported to damage sorghum [Sorghum bicolor (L.) Moench] in the United States in Louisiana and Texas in 2013, and was subsequently detected in Oklahoma and the Mississippi Delta. In 2014, the aphid spread and was eventually reported in state...

  1. Anomalous stylet punctures of phloem sieve elements by aphids

    NARCIS (Netherlands)

    Tjallingii, W.F.; Gabrys, B.

    1999-01-01

    A deviating type of potential drop (pd), i.e. the electrically recorded intracellular punctures during the pathway phase of plant penetration by aphids, is described and discussed. This so-called repetitive pd (R-pd) has been observed in 4 aphid species, two on herbs and two on sycamore. Apart from

  2. 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 tax

  3. Predator efficiency reconsidered for a ladybird-aphid system

    Directory of Open Access Journals (Sweden)

    Pavel eKindlmann

    2015-03-01

    Full Text Available Some experiments indicate that ladybirds can significantly suppress aphid abundance. For example, exclusion of predators by caging aphid-infested plants repeatedly results in higher aphid populations and faster aphid population growth rates. However, aphidophagous ladybirds have never proved effective in controlling aphid populations in the field, which is consistent with the theoretical prediction that long-lived predators cannot be effective in controlling a short-lived prey (the generation time ratio hypothesis, GTR. To resolve this paradox, field experiments, involving two species of ladybirds, Coccinella septempunctata bruckii and Harmonia axyridis were used to determine their efficiency in suppressing populations of the aphid, Aphis gossypii, on small shrubs of Hibiscus syriacus under natural conditions. Instead of by caging, the effect of each ladybird species on aphid population dynamics was determined by removing all the eggs of C. septempunctata from 8 shrubs, those of H. axyridis from a further 8 shrubs, all those of both species from an additional 12 shrubs and leaving the eggs on 6 control shrubs. These predators did not have a negative effect on the peak numbers of the aphids. Thus one should be cautious when interpreting the results of cage experiments, used to assess the efficiency of predators in reducing the abundance of their prey.

  4. Detection of novel QTLs for foxglove aphid resistance in soybean

    Science.gov (United States)

    Foxglove aphid, Aulacorthum solani (Kaltenbach), is a Hemipteran insect that infected a wide variety of plants worldwide and caused serious yield losses in crops. The objective of this study was to identify the putative QTL for foxglove aphid resistance in wild soybean, PI 366121, (Glycine soja Sieb...

  5. Keystone Herbivores and the Evolution of Plant Defenses

    NARCIS (Netherlands)

    Poelman, Erik H.; Kessler, André

    2016-01-01

    Plants need to defend themselves against a diverse and dynamic herbivore community. Such communities may be shaped by keystone herbivores that through their feeding alter the plant phenotype as well as the likelihood of attack by other herbivores. Here, we discuss such herbivores that have a larg

  6. Cognitive functions in neurofibromatosis type 1 patients and unaffected siblings.

    Science.gov (United States)

    Erdoğan-Bakar, Emel; Cinbiş, Mine; Ozyürek, Hamit; Kiriş, Nurcihan; Altunbaşak, Sakir; Anlar, Banu

    2009-01-01

    Attention, learning, and perceptual problems have been reported at various degrees and rates in neurofibromatosis type 1 (NF1). We aimed to define the cognitive profiles frequently associated with NF1. Children and adolescents with NF1 (n=58) were tested using Wechsler Intelligence Scales for Children-Revised (WISC-R), Judgment of Line Orientation, and Bender Visual-Motor Gestalt tests. Comparison groups were unaffected siblings of NF1 patients (n=20), children with attention deficit and hyperactivity disorder (ADHD, n=40), and normal children (n=40). No difference was found between familial or sporadic NF1 cases. Seventeen/58 (29%) of NF1 cases had a full scale IQ80 (n=27) scored lower in WISC-R subtests measuring visual perception when compared to a healthy control group of similar intelligence, and lower in arithmetic but better in Bender-Gestalt and Judgment of Line Orientation tests when compared to an ADHD group of similar intelligence. These results indicate a high prevalence of mental retardation in a clinical NF1 series. NF1 patients who have normal intelligence may have impaired visual perception, but their visual perceptual problems are less than in ADHD. The tendency of unaffected siblings of NF1 patients to have mildly but consistently low test scores compared to healthy controls needs to be studied further for underlying genetic or environmental factors.

  7. Executive functioning in anorexia nervosa patients and their unaffected relatives.

    Science.gov (United States)

    Galimberti, Elisa; Fadda, Emma; Cavallini, Maria Cristina; Martoni, Riccardo Maria; Erzegovesi, Stefano; Bellodi, Laura

    2013-08-15

    Formal genetic studies suggested a substantial genetic influence for anorexia nervosa (AN), but currently results are inconsistent. The use of the neurocognitive endophenotype approach may facilitate our understanding of the AN pathophysiology. We investigated decision-making, set-shifting and planning in AN patients (n=29) and their unaffected relatives (n=29) compared to healthy probands (n=29) and their relatives (n=29). The Iowa Gambling Task (IGT), the Tower of Hanoi (ToH) and the Wisconsin Card Sorting Test (WCST) were administered. Concordance rates and heritability indices were also calculated in probands/relatives. Impaired performance on the IGT and the WCST were found in both AN probands and their relatives, although planning appeared to be preserved. The IGT heritability index suggested the presence of genetic effects that influence this measure. No evidence for genetic effects was found for the WCST. The results suggest the presence of a shared dysfunctional executive profile in women with AN and their unaffected relatives, characterized by deficient decision-making and set-shifting. Concordance analysis strongly suggests that these impairments aggregate in AN families, supporting the hypothesis that they may constitute biological markers for AN. Decision-making impairment presents a moderate heritability, suggesting that decision-making may be a candidate endophenotype for AN. PMID:23122554

  8. Tracking the global dispersal of a cosmopolitan insect pest, the peach potato aphid

    OpenAIRE

    Kasprowicz Louise; Margaritopoulos John T; Malloch Gaynor L; Fenton Brian

    2009-01-01

    Abstract Background Global commerce and human transportation are responsible for the range expansion of various insect pests such as the plant sucking aphids. High resolution DNA markers provide the opportunity to examine the genetic structure of aphid populations, identify aphid genotypes and infer their evolutionary history and routes of expansion which is of value in developing management strategies. One of the most widespread aphid species is the peach-potato aphid Myzus persicae, which i...

  9. Transitive inference deficits in unaffected biological relatives of schizophrenia patients.

    Science.gov (United States)

    Onwuameze, Obiora E; Titone, Debra; Ho, Beng-Choon

    2016-08-01

    Currently available treatments have limited efficacy in remediating cognitive impairment in schizophrenia. Efforts to facilitate cognition-enhancing drug discovery recommend the use of varied experimental cognitive paradigms (including relational memory) as assessment tools in clinical drug trials. Although relational memory deficits are increasingly being recognized as a reliable cognitive marker of schizophrenia, relational memory performance among unaffected biological relatives remains unknown. Therefore, we evaluated 73 adolescents or young adults (22 first- and 26 second-degree relatives of schizophrenia patients and 25 healthy controls (HC)) using a well-validated transitive inference (TI) experimental paradigm previously used to demonstrate relational memory impairment in schizophrenia. We found that TI deficits were associated with schizophrenia risk with first-degree relatives showing greater impairment than second-degree relatives. First-degree relatives had poorer TI performance with significantly lower accuracy and longer response times than HC when responding to TI probe pairs. Second-degree relatives had significantly quicker response times than first-degree relatives and were more similar to HC in TI performance. We further explored the relationships between TI performance and neurocognitive domains implicated in schizophrenia. Among HC, response times were inversely correlated with FSIQ, verbal learning, processing speed, linguistic abilities and working memory. In contrast, relatives (first-degree in particular) had a differing pattern of TI-neurocognition relationships, which suggest that different brain circuits may be used when relatives encode and retrieve relational memory. Our finding that unaffected biological relatives of schizophrenia patients have TI deficits lends further support for the use of relational memory construct in future pro-cognition drug studies. PMID:27050477

  10. 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.

  11. Life-history strategies affect aphid preference for yellowing leaves.

    Science.gov (United States)

    Holopainen, Jarmo K; Semiz, Gürkan; Blande, James D

    2009-10-23

    According to the nutrient-translocation hypothesis, yellowing tree leaves are colonized by aphids at the end of the growing season owing to improved availability of nutrients in the phloem sap after chlorophyll degradation. We measured aphid densities on potted Betula pendula seedlings in a field site where a small proportion of foliage rapidly turned yellow before normal autumn coloration as a consequence of root anoxia. The number of adults and nymphs of the birch-feeding specialist aphids Euceraphis betulae, Betulaphis brevipilosa and Callipterinella tuberculata were counted from leaves on each of the 222 plants. Aphids were detected on 19 per cent of green leaves and on 41 per cent of yellow leaves. There was no indication of aphid avoidance of yellow leaves, and the number of winged (alate) viviparous E. betulae adults and their nymphs were significantly higher on yellow leaves than on green leaves, while the numbers of apterous B. brevipilosa and C. tuberculata did not differ between the leaf colour types. Our result suggests that only aphid species with alate generation during colour change can take advantage of yellowing leaves. This may explain the exceptional abundance of E. betulae compared with other aphid species on birches. PMID:19535364

  12. Color polymorphism in an aphid is maintained by attending ants.

    Science.gov (United States)

    Watanabe, Saori; Murakami, Taiga; Yoshimura, Jin; Hasegawa, Eisuke

    2016-09-01

    The study of polymorphisms is particularly informative for enhancing our understanding of phenotypic and genetic diversity. The persistence of polymorphism in a population is generally explained by balancing selection. Color polymorphisms that are often found in many insects and arthropods are prime examples of the maintenance of polymorphisms via balancing selection. In some aphids, color morphs are maintained through frequency-dependent predation by two predatory insects. However, the presence of color polymorphism in ant-attended aphids cannot be explained by traditional balancing selection because these aphids are free from predation. We examined the selective advantages of the existence of two color (red and green) morphs in the ant-attended aphid, Macrosiphoniella yomogicola, in fields. We measured the degree of ant attendance on aphid colonies with different proportions of color morphs. The results show that the ants strongly favor aphid colonies with intermediate proportions of the two color morphs. The relationship between the degree of ant attendance and the proportion of color morphs in the field is convex when aphid colony size and ant colony size are controlled. This function has a peak of approximately 65% of green morphs in a colony. This system represents the first case of a balancing polymorphism that is not maintained by opposing factors but by a symbiotic relationship. PMID:27617289

  13. 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.

  14. Aphids (Hemiptera, Aphididae on ornamental plants in greenhouses in Bulgaria

    Directory of Open Access Journals (Sweden)

    Mariya Yovkova

    2013-07-01

    Full Text Available Investigations on the species composition and host range of aphids on ornamental greenhouse plants in Bulgaria was conducted over a period of five years, from 2008 to 2012. Twenty greenhouses, growing ornamentals for landscaping, plant collections and other purposes were observed. They were located in the regions of Sofia, Plovdiv, Smolyan, Pavlikeni, Varna and Burgas. The total number of collected aphid samples was 279. Their composition included 33 aphid species and one subspecies from 13 genera and 5 subfamilies. Twenty-eight species were found to belong to subfamily Aphidinae. Almost 70 % of all recorded species were polyphagous. The most widespread aphid species was Myzus persicae, detected in 13 greenhouses all year round, followed by Aulacorthum solani (10 greenhouses and Aphis gossypii (9 greenhouses. The widest host range was shown by Myzus persicae (43 hosts, Aulacorthum solani (32 hosts and Aulacorthum circumflexum (23 hosts.The list of host plants includes 114 species from 95 genera and 58 families. The greatest variety of aphid species was detected on Hibiscus (9 species. Out of all aphid samples 12.9 % were collected on Hibiscus and 6.8 %, on Dendranthema. The greatest variety of aphid species was detected on Hibiscus (9 species.Periphyllus californiensis and Aphis (Aphis fabae mordvilkoi are reported for the first time for Bulgaria. Furthermore, Aphis spiraecola has been found in new localities and has widened its host range in this country.

  15. Bacterial communities of two parthenogenetic aphid species cocolonizing two host plants across the Hawaiian Islands.

    Science.gov (United States)

    Jones, Ryan T; Bressan, Alberto; Greenwell, April M; Fierer, Noah

    2011-12-01

    Aphids (Hemiptera: Aphididae) have been the focus of several studies with respect to their interactions with inherited symbionts, but bacterial communities of most aphid species are still poorly characterized. In this research, we used bar-coded pyrosequencing to characterize bacterial communities in aphids. Specifically, we examined the diversity of bacteria in two obligately parthenogenetic aphid species (the melon aphid, Aphis gossypii, and the cardamom aphid, Pentalonia caladii) cocolonizing two plant species (taro, Colocasia esculenta, and ginger, Alpinia purpurata) across four Hawaiian Islands (Hawaii, Kauai, Maui, and Oahu). Results from this study revealed that heritable symbionts dominated the bacterial communities for both aphid species. The bacterial communities differed significantly between the two species, and A. gossypii harbored a more diverse bacterial community than P. caladii. The bacterial communities also differed across aphid populations sampled from the different islands; however, communities did not differ between aphids collected from the two host plants. PMID:21965398

  16. The specificity of herbivore-induced plant volatiles in attracting herbivore enemies.

    Science.gov (United States)

    Clavijo McCormick, Andrea; Unsicker, Sybille B; Gershenzon, Jonathan

    2012-05-01

    Plants respond to herbivore attack by emitting complex mixtures of volatile compounds that attract herbivore enemies, both predators and parasitoids. Here, we explore whether these mixtures provide significant value as information cues in herbivore enemy attraction. Our survey indicates that blends of volatiles released from damaged plants are frequently specific depending on the type of herbivore and its age, abundance and feeding guild. The sensory perception of plant volatiles by herbivore enemies is also specific, according to the latest evidence from studies of insect olfaction. Thus, enemies do exploit the detailed information provided by plant volatile mixtures in searching for their prey or hosts, but this varies with the diet breadth of the enemy.

  17. Environmental RNAi in herbivorous insects.

    Science.gov (United States)

    Ivashuta, Sergey; Zhang, Yuanji; Wiggins, B Elizabeth; Ramaseshadri, Partha; Segers, Gerrit C; Johnson, Steven; Meyer, Steve E; Kerstetter, Randy A; McNulty, Brian C; Bolognesi, Renata; Heck, Gregory R

    2015-05-01

    Environmental RNAi (eRNAi) is a sequence-specific regulation of endogenous gene expression in a receptive organism by exogenous double-stranded RNA (dsRNA). Although demonstrated under artificial dietary conditions and via transgenic plant presentations in several herbivorous insects, the magnitude and consequence of exogenous dsRNA uptake and the role of eRNAi remains unknown under natural insect living conditions. Our analysis of coleopteran insects sensitive to eRNAi fed on wild-type plants revealed uptake of plant endogenous long dsRNAs, but not small RNAs. Subsequently, the dsRNAs were processed into 21 nt siRNAs by insects and accumulated in high quantities in insect cells. No accumulation of host plant-derived siRNAs was observed in lepidopteran larvae that are recalcitrant to eRNAi. Stability of ingested dsRNA in coleopteran larval gut followed by uptake and transport from the gut to distal tissues appeared to be enabling factors for eRNAi. Although a relatively large number of distinct coleopteran insect-processed plant-derived siRNAs had sequence complementarity to insect transcripts, the vast majority of the siRNAs were present in relatively low abundance, and RNA-seq analysis did not detect a significant effect of plant-derived siRNAs on insect transcriptome. In summary, we observed a broad genome-wide uptake of plant endogenous dsRNA and subsequent processing of ingested dsRNA into 21 nt siRNAs in eRNAi-sensitive insects under natural feeding conditions. In addition to dsRNA stability in gut lumen and uptake, dosage of siRNAs targeting a given insect transcript is likely an important factor in order to achieve measurable eRNAi-based regulation in eRNAi-competent insects that lack an apparent silencing amplification mechanism.

  18. Climate warming and predation risk during herbivore ontogeny.

    Science.gov (United States)

    Barton, Brandon T

    2010-10-01

    Phenological effects of climate change are expected to differ among species, altering interactions within ecological communities. However, the nature and strength of these effects can vary during ontogeny, so the net community-level effects will be the result of integration over an individual's lifetime. I resolved the mechanism driving the effects of warming and spider predation risk on a generalist grasshopper herbivore at each ontogenetic stage and quantified the treatment effects on a measure of reproductive fitness. Spiders caused nymphal grasshoppers to increase the proportion of herbs in their diet, thus having a positive indirect effect on grasses and a negative indirect effect on herbs. Warming strengthened the top-down effect by affecting spiders and grasshoppers differently. In cooler, ambient conditions, grasshoppers and spiders had a high degree of spatial overlap within the plant canopy. Grasshopper position was unaffected by temperature, but spiders moved lower in the canopy in response to warming. This decreased the spatial overlap between predator and prey, allowing nymphal grasshoppers to increase daily feeding time. While spiders decreased grasshopper growth and reproductive fitness in ambient conditions, spiders had no effect on grasshopper fitness in warmed treatments. The study demonstrates the importance of considering the ontogeny of behavior when examining the effects of climate change on trophic interactions. PMID:21058542

  19. 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

    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...... 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...... benefitting the domesticated aphids as long as their clone-mates reproduce successfully. The cost-benefit logic of this type of polyculture husbandry has striking analogies with human farming practices based on slaughtering young animals for meat to maximize milk-production by a carefully regulated adult...

  20. Identification of Soybean Resources of Resistance to Aphids

    Institute of Scientific and Technical Information of China (English)

    WU Tian-long; MA Xiao-hong; YAO Lu-ming; WANG Biao

    2009-01-01

    Four soybean [Glycine max (L.) Merr.] cultivars with soybean aphid resistance (Aphis glycines Matsmura), P189, P203, P574,and P746, were identified in field test, choice test, and non-choice test. The grade of resistance to aphids and the damage index of P189, P203, and P746 were significantly different from the susceptible cultivars (P=0.05). P574 and P746 showed antibiosis resistance, preventing aphids from reproducing on the plants. P203 showed antixenosis resistance, preventing aphids from reproducing in field test and choice test, but susceptible in non-choice test. Population development on plants was significantly different in field test, choice test, and non-choice test, which was caused by different selective pressures.

  1. Genome sequence of the pea aphid Acyrthosiphon pisum

    DEFF Research Database (Denmark)

    Richards, S.; Gibbs, R. A.; Gerardo, N. M.;

    2010-01-01

    Aphids are important agricultural pests and also biological models for studies of insect-plant interactions, symbiosis, virus vectoring, and the developmental causes of extreme phenotypic plasticity. Here we present the 464 Mb draft genome assembly of the pea aphid Acyrthosiphon pisum. This first...... published whole genome sequence of a basal hemimetabolous insect provides an outgroup to the multiple published genomes of holometabolous insects. Pea aphids are host-plant specialists, they can reproduce both sexually and asexually, and they have coevolved with an obligate bacterial symbiont. Here we...... include genes involved in chromatin modification, miRNA synthesis, and sugar transport. Gene losses include genes central to the IMD immune pathway, selenoprotein utilization, purine salvage, and the entire urea cycle. The pea aphid genome reveals that only a limited number of genes have been acquired...

  2. Venomous protease of aphid soldier for colony defense

    OpenAIRE

    Kutsukake, Mayako; Shibao, Harunobu; Nikoh, Naruo; Morioka, Mizue; Tamura, Tomohiro; Hoshino, Tamotsu; Ohgiya, Satoru; Fukatsu, Takema

    2004-01-01

    In social aphids, morphological, behavioral, and physiological differences between soldiers and normal insects are attributed to differences in gene expression between them, because they are clonal offspring parthenogenetically produced by the same mothers. By using cDNA subtraction, we identified a soldier-specific cysteine protease of the family cathepsin B in a social aphid, Tuberaphis styraci, with a second-instar soldier caste. The cathepsin B gene was specifically expressed in soldiers ...

  3. Artificial nighttime light changes aphid-parasitoid population dynamics

    OpenAIRE

    Dirk Sanders; Rachel Kehoe; Katie Tiley; Jonathan Bennie; Dave Cruse; Davies, Thomas W; F J Frank van Veen; Gaston, Kevin J

    2015-01-01

    Artificial light at night (ALAN) is recognized as a widespread and increasingly important anthropogenic environmental pressure on wild species and their interactions. Understanding of how these impacts translate into changes in population dynamics of communities with multiple trophic levels is, however, severely lacking. In an outdoor mesocosm experiment we tested the effect of ALAN on the population dynamics of a plant-aphid-parasitoid community with one plant species, three aphid species an...

  4. Spontaneous electrical activity recorded from the aphid central nervous system

    OpenAIRE

    Nguyen, Dan-Thanh T.; Blacker, Melissa J.; Goodchild, James A.

    2012-01-01

    Whilst many classes of insecticides target the insect central nervous system (CNS), their effects in the CNS of pest aphids have not been demonstrated. In this report, we describe an electrophysiological method for recording spontaneous neuronal activity from the giant willow aphid (Tuberolachnus salignus). Using extracellular recording electrodes and two analysis methods (threshold and template search), spontaneous spike activity was shown to exhibit sensitivity to the neuroexcitatory insect...

  5. New data about the Costa Rican aphid fauna (Hemiptera, Aphididae)

    OpenAIRE

    Zamora Mejías, D.; Pérez Hidalgo, N.; W. Villalobos; Hanson, P

    2012-01-01

    Aphids were collected from 39 locations throughout Costa Rica, representing a wide altitudinal range, and from both crops and native plants. In total, 48 species of aphids were identified, associated with 62 families and 111 species of plants, many of these representing new host plant records. Aphis nasturtii Kaltenbach, 1843 is reported here for the first time in Central America and Trichosiphonaphis (Xenomyzus) polygoni (van der Goot, 1917) for the ...

  6. 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.......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....

  7. Changes in motor function in the unaffected hand of stroke patients should not be ignored

    Institute of Scientific and Technical Information of China (English)

    Lingli Zhang; Peihong Li; Zhibang Mao; Xiang Qi; Jun Zou; Zhusheng Yu

    2014-01-01

    Motor function changes in the unaffected hand of stroke patients with hemiplegia. These chang-es are often ignored by clinicians owing to the extent of motor disability of the affected hand. Finger tapping frequency and Lind-mark hand function score showed that the motor function of unaffected hands in stroke patients was poorer than that of a healthy control hand. After 2 weeks of rehabilitation treatment, motor function of the unaffected hand of stroke patients was obviously improved. Therefore, attention should also be paid to motor function in the unaffect-ed hand of stroke patients with hemiplegia during rehabilitation.

  8. Ecology of herbivorous arthropods in urban landscapes.

    Science.gov (United States)

    Raupp, Michael J; Shrewsbury, Paula M; Herms, Daniel A

    2010-01-01

    Urbanization affects communities of herbivorous arthropods and provides opportunities for dramatic changes in their abundance and richness. Underlying these changes are creation of impervious surfaces; variation in the density, diversity, and complexity of vegetation; and maintenance practices including pulsed inputs of fertilizers, water, and pesticides. A rich body of knowledge provides theoretical underpinnings for predicting and understanding impacts of urbanization on arthropods. However, relatively few studies have elucidated mechanisms that explain patterns of insect and mite abundance and diversity across urbanization gradients. Published accounts suggest that responses to urbanization are often taxon specific, highly variable, and linked to properties of urbanization that weaken top-down and/or bottom-up processes, thereby destabilizing populations of herbivores and their natural enemies. In addition to revealing patterns in diversity and abundance of herbivores across urbanization gradients, a primary objective of this review is to examine mechanisms underlying these patterns and to identify potential hypotheses for future testing.

  9. Stylet penetration behaviors of the cotton aphid Aphis gossypii on transgenic Bt cotton

    Institute of Scientific and Technical Information of China (English)

    Kun Xue; Xiao-Ying Wang; Cui-Hong Huang; Rong-Jiang Wang; Biao Liu; Feng-Ming Yan; Chong-Ren Xu

    2009-01-01

    Stylet penetration behaviors of cotton aphids Aphis gossypii Glover on a tmnsgenic cotton line "GK-12" expressing Bt toxic protein ofCry1A (Bt cotton) and a non-Bt conventional cotton line "Simian-3" (CK cotton) were recorded with the direct current electrical penetration graph (DC-EPG) technique. Cotton aphids reared on Bt cotton (abbreviated as Bt-aphids) and its parental non-Bt control line (CK-aphids) for more than 20 generations each, were used for recordings on two cotton lines. Among 47 selected parameters reflecting the activities of aphid stylets within plant tissues, there were eight parameters of CK-aphids showing significant differences between the performances of CK-aphids on Bt cotton and CK cotton, while for Bt-aphids, all the parameters were statistically equal between the performances on the two cotton lines. All parameters with significant differences indicated that CK-aphids could penetrate into Bt cotton more easily, but the phloem saps of Bt cotton were not as good as those of regular cotton for CK-aphids. Based on the present results, we concluded that there were some factors in Bt cotton affecting penetration behaviors of CK-aphids, but it just took several generations for CK-aphids to completely adapt Bt cotton, and Bt-aphids could feed on two cotton lines without difficulty.

  10. Do plant viruses facilitate their aphid vectors by inducing symptoms that alter behavior and performance?

    Science.gov (United States)

    Hodge, Simon; Powell, Glen

    2008-12-01

    Aphids can respond both positively and negatively to virus-induced modifications of the shared host plant. It can be speculated that viruses dependent on aphids for their transmission might evolve to induce changes in the host plant that attract aphids and improve their performance, subsequently enhancing the success of the pathogen itself. We studied how pea aphids [Acyrthosiphon pisum (Harris)] responded to infection of tic beans (Vicia faba L.) by three viruses with varying degrees of dependence on this aphid for their transmission: pea enation mosaic virus (PEMV), bean yellow mosaic virus (BYMV), and broad bean mottle virus (BBMV). BYMV has a nonpersistent mode of transmission by aphids, whereas PEMV is transmitted in a circulative-persistent manner. BBMV is not aphid transmitted. When reared on plants infected by PEMV, no changes in aphid survival, growth, or reproductive performance were observed, whereas infection of beans by the other aphid-dependent virus, BYMV, actually caused a reduction in aphid survival in some assays. None of the viruses induced A. pisum to increase production of winged progeny, and aphids settled preferentially on leaf tissue from plants infected by all three viruses, the likely mechanism being visual responses to yellowing of foliage. Thus, in this system, the attractiveness of an infected host plant and its quality in terms of aphid growth and reproduction were not related to the pathogen's dependence on the aphid for transmission to new hosts. PMID:19161702

  11. The abundance of herbivorous fish on an inshore Red Sea reef following a mass coral bleaching event

    KAUST Repository

    Khalil, Maha T.

    2013-01-08

    A healthy herbivore community is critical for the ability of a reef to resist and recover from severe disturbances and to regain lost coral cover (i.e., resilience). The densities of the two major herbivorous fish groups (the family Acanthuridae and scarine labrids) were comparatively studied for an inshore reef that was severely impacted by a mass coral bleaching event in 2010 and an unaffected reef within the same region. Densities were found to be significantly higher on the affected reef, most likely due to the high algal densities on that reef. However, densities of herbivores on both reefs were found to be on average about 1-2 orders of magnitude lower than previously published reports from some Pacific reefs and from Red Sea reefs in the Gulf of Aqaba and only slightly higher than Caribbean reefs. Thus, it is predicted that recovery for this reef and similarly affected reefs may be very slow. The protection of herbivores from overfishing and the introduction of other management strategies that maximize reef resilience in Saudi Arabian waters are highly recommended. © 2013 Springer Science+Business Media Dordrecht.

  12. Alien interference: disruption of infochemical networks by invasive insect herbivores

    NARCIS (Netherlands)

    Desurmont, Gaylord A.; Harvey, Jeff A.; van Dam, Nicole M.; Cristescu, Simona M.; Schiestl, Florian P.; Cozzolino, Salvatore; Anderson, Peter; Larsson, Mattias C.; Kindlmann, Pavel; Danner, Holger; Turlings, Ted C. J.

    2014-01-01

    Insect herbivores trigger various biochemical changes in plants, and as a consequence, affect other organisms that are associated with these plants. Such plant-mediated indirect effects often involve herbivore-induced plant volatiles (HIPVs) that can be used as cues for foraging herbivores and their

  13. 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, ...

  14. Warming strengthens an herbivore-plant interaction.

    Science.gov (United States)

    O'Connor, Mary I

    2009-02-01

    Temperature has strong, predictable effects on metabolism. Through this mechanism, environmental temperature affects individuals and populations of poikilotherms by determining rates of resource use, growth, reproduction, and mortality. Predictable variation in metabolic processes such as growth and reproduction could affect the strength of species interactions, but the community-level consequences of metabolic temperature dependence are virtually unexplored. I experimentally tested the hypothesis that plant-herbivore interaction strength increases with temperature using a common species of marine macroalga (Sargassum filipendula) and the grazing amphipod Ampithoe longimana. Increasing temperature increased per capita interaction strength in two independent experiments and reversed a positive effect of temperature on plant growth. Temperature did not alter palatability of plant tissue to herbivores or average herbivore feeding rate. A predictable effect of temperature on herbivore-plant interaction strength could provide key information toward understanding local food web responses to changing temperatures at different spatial and temporal scales. Efforts to extend the effects of physiological mechanisms to larger scale patterns, including projections of the ecological effects of climate change, must be expanded to include the effects of changing conditions on trophic interactions. PMID:19323223

  15. The Enigmatic Universe of the Herbivore Gut.

    Science.gov (United States)

    Glass, N Louise

    2016-07-01

    The herbivore gut is a fascinating ecosystem exquisitely adapted to plant biomass degradation. Within this ecosystem, anaerobic fungi invade biomass and secrete hydrolytic enzymes. In a recent study, Solomon et al. characterized three anaerobic fungi by transcriptomics, proteomics, and functional analyses to identify novel components essential for plant biomass deconstruction.

  16. Experimental support of the stress-gradient hypothesis in herbivore-herbivore interactions

    OpenAIRE

    Dangles, Olivier; Herrera, M; Anthelme, Fabien

    2013-01-01

    The stress-gradient hypothesis (SGH) postulates an increase in the frequency of positive species interactions at increasing amounts of stress. While the SGH has been extensively tested in plant-plant interactions along abiotic stresses, it remains unclear whether this hypothesis could apply to higher trophic levels, such as herbivores, along biotic stress gradients. To address this issue, we investigated how the interaction between two potato herbivores may change along a stress gradient crea...

  17. 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.

  18. Aphidius gifuensis: a promising parasitoid for biological control of two important aphid species in sweet pepper

    NARCIS (Netherlands)

    Messelink, G.J.; Bloemhard, C.M.J.; Hoogerbrugge, H.; Schelt, van J.

    2011-01-01

    The parasitoid Aphidius gifuensis is able to parasitize both the green peach aphid Myzus persicae and the foxglove aphid Aulacorthum solani in sweet pepper. In a greenhouse experiment we showed that rates of parasitism on green peach aphids alone were equal to the commonly used Aphidius colemani, bu

  19. 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....

  20. National Plant Diagnostic Network, Taxonomic training videos: Introduction to AphID

    Science.gov (United States)

    Training is a critical part of aphid (Hemiptera: Aphididae) identification. This video provides visual instruction on the use of the expert system, AphID, for aphid examination and identification. The video demonstrates the use of different training modules that allow the user to gain familiarity wi...

  1. Multi-factor climate change effects on insect herbivore performance

    DEFF Research Database (Denmark)

    Scherber, Christoph; Gladbach, David J; Stevnbak, Karen;

    2013-01-01

    The impact of climate change on herbivorous insects can have far-reaching consequences for ecosystem processes. However, experiments investigating the combined effects of multiple climate change drivers on herbivorous insects are scarce. We independently manipulated three climate change drivers (CO......, nitrogen, and water content. Overall, drought was the most important factor for this insect herbivore. Our study shows that weight and survival of insect herbivores may decline under future climate. The complexity of insect herbivore responses increases with the number of combined climate change drivers....

  2. Predicting the occurrence of alate aphids in Brassicaceae

    Directory of Open Access Journals (Sweden)

    Francisco Jorge Cividanes

    2012-04-01

    Full Text Available The objective of this work was to predict the occurrence of alates of Brevicoryne brassicae, Lipaphis erysimi, and Myzus persicae (Hemiptera, Aphididae in Brassicaceae. The alate aphids were collected in yellow water traps from July 1997 to August 2005. Aphid population peaks were predicted using a degree‑day model. The meteorological factors, temperature, air relative humidity, rainfall, and sunshine hours, were used to provide precision indexes to evaluate the best predictor for the date of the first capture of alate aphids by the traps. The degree‑day model indicated that the peak population of the evaluated aphid species can be predicted using one of the following biofix dates: January 1st, June 1st, and the date of the first capture of the alate aphid species by the yellow water traps. The best predictor of B. brassicae occurrence is the number of days with minimum temperature >15°C, and of L. erysimi and M. persicae, the number of days with rainfall occurrence.

  3. Functional genomics of Buchnera and the ecology of aphid hosts.

    Science.gov (United States)

    Moran, Nancy A; Degnan, Patrick H

    2006-04-01

    In many animal groups, mutualistic bacterial symbionts play a central role in host ecology, by provisioning rare nutrients and thus enabling specialization on restricted diets. Among such symbionts, genomic studies are most advanced for Buchnera, the obligate symbiont of aphids, which feed on phloem sap. The contents of the highly reduced Buchnera genomes have verified its role in aphid nutrition. Comparisons of Buchnera gene sets indicate ongoing, irreversible gene losses that are expected to affect aphid nutritional needs. Furthermore, almost all regulatory genes have been eliminated, raising the question of whether and how gene expression responds to environmental change. Microarray studies on genome-wide expression indicate that Buchnera has evolved some constitutive changes in gene expression: homologues of heat stress genes have elevated transcript levels in Buchnera (relative to other bacteria) even in the absence of stress. Additionally, the microarray results indicate that responses to heat stress and to amino acid availability are both few and modest. Observed responses are consistent with control by the few ancestral regulators retained in the genome. Initial studies on the role of host genes in mediating the symbiosis reveal distinctive expression patterns in host cells harbouring Buchnera. In the near future, a complete genome of pea aphid will accelerate progress in understanding the functional integration of aphid and Buchnera genomes. Although information for other insect symbioses is relatively limited, studies on symbionts of carpenter ants and tsetse flies indicate many similarities to Buchnera. PMID:16626452

  4. Relationship of soybean aphid (Hemiptera: Aphididae) to soybean plant nutrients, landscape structure, and natural enemies.

    Science.gov (United States)

    Noma, Takuji; Gratton, Claudio; Colunga-Garcia, Manuel; Brewer, Michael J; Mueller, Emily E; Wyckhuys, Kris A G; Heimpel, George E; O'Neal, Matthew E

    2010-02-01

    In the north central United States, populations of the exotic soybean aphid, Aphis glycines Matsumura (Hemiptera: Aphididae), are highly variable across space, complicating effective aphid management. In this study we examined relationships of plant nutrients, landscape structure, and natural enemies with soybean aphid abundance across Iowa, Michigan, Minnesota, and Wisconsin, representing the range of conditions where soybean aphid outbreaks have occurred since its introduction. We sampled soybean aphid and its natural enemies, quantified vegetation land cover and measured soybean nutrients (potassium [K] and nitrogen [N]) in 26 soybean sites in 2005 and 2006. Multiple regression models found that aphid abundance was negatively associated with leaf K content in 2005, whereas it was negatively associated with habitat diversity (Simpson's index) and positively associated with leaf N content in 2006. These variables accounted for 25 and 27% of aphid variability in 2005 and 2006, respectively, suggesting that other sources of variability are also important. In addition, K content of soybean plants decreased with increasing prevalence of corn-soybean cropland in 2005, suggesting that landscapes that have a high intensification of agriculture (as indexed by increasing corn and soybean) are more likely to have higher aphid numbers. Soybean aphid natural enemies, 26 species of predators and parasitoids, was positively related to aphid abundance; however, enemy-to-aphid abundance ratios were inversely related to aphid density, suggesting that soybean aphids are able to escape control by resident natural enemies. Overall, soybean aphid abundance was most associated with soybean leaf chemistry and landscape heterogeneity. Agronomic options that can ameliorate K deficiency and maintaining heterogeneity in the landscape may reduce aphid risk.

  5. Virulent Diuraphis noxia Aphids Over-Express Calcium Signaling Proteins to Overcome Defenses of Aphid-Resistant Wheat Plants.

    Science.gov (United States)

    Sinha, Deepak K; Chandran, Predeesh; Timm, Alicia E; Aguirre-Rojas, Lina; Smith, C Michael

    2016-01-01

    The Russian wheat aphid, Diuraphis noxia, an invasive phytotoxic pest of wheat, Triticum aestivum, and barley, Hordeum vulgare, causes huge economic losses in Africa, South America, and North America. Most acceptable and ecologically beneficial aphid management strategies include selection and breeding of D. noxia-resistant varieties, and numerous D. noxia resistance genes have been identified in T. aestivum and H. vulgare. North American D. noxia biotype 1 is avirulent to T. aestivum varieties possessing Dn4 or Dn7 genes, while biotype 2 is virulent to Dn4 and avirulent to Dn7. The current investigation utilized next-generation RNAseq technology to reveal that biotype 2 over expresses proteins involved in calcium signaling, which activates phosphoinositide (PI) metabolism. Calcium signaling proteins comprised 36% of all transcripts identified in the two D. noxia biotypes. Depending on plant resistance gene-aphid biotype interaction, additional transcript groups included those involved in tissue growth; defense and stress response; zinc ion and related cofactor binding; and apoptosis. Activation of enzymes involved in PI metabolism by D. noxia biotype 2 aphids allows depletion of plant calcium that normally blocks aphid feeding sites in phloem sieve elements and enables successful, continuous feeding on plants resistant to avirulent biotype 1. Inhibition of the key enzyme phospholipase C significantly reduced biotype 2 salivation into phloem and phloem sap ingestion.

  6. Virulent Diuraphis noxia Aphids Over-Express Calcium Signaling Proteins to Overcome Defenses of Aphid-Resistant Wheat Plants.

    Directory of Open Access Journals (Sweden)

    Deepak K Sinha

    Full Text Available The Russian wheat aphid, Diuraphis noxia, an invasive phytotoxic pest of wheat, Triticum aestivum, and barley, Hordeum vulgare, causes huge economic losses in Africa, South America, and North America. Most acceptable and ecologically beneficial aphid management strategies include selection and breeding of D. noxia-resistant varieties, and numerous D. noxia resistance genes have been identified in T. aestivum and H. vulgare. North American D. noxia biotype 1 is avirulent to T. aestivum varieties possessing Dn4 or Dn7 genes, while biotype 2 is virulent to Dn4 and avirulent to Dn7. The current investigation utilized next-generation RNAseq technology to reveal that biotype 2 over expresses proteins involved in calcium signaling, which activates phosphoinositide (PI metabolism. Calcium signaling proteins comprised 36% of all transcripts identified in the two D. noxia biotypes. Depending on plant resistance gene-aphid biotype interaction, additional transcript groups included those involved in tissue growth; defense and stress response; zinc ion and related cofactor binding; and apoptosis. Activation of enzymes involved in PI metabolism by D. noxia biotype 2 aphids allows depletion of plant calcium that normally blocks aphid feeding sites in phloem sieve elements and enables successful, continuous feeding on plants resistant to avirulent biotype 1. Inhibition of the key enzyme phospholipase C significantly reduced biotype 2 salivation into phloem and phloem sap ingestion.

  7. Virulent Diuraphis noxia Aphids Over-Express Calcium Signaling Proteins to Overcome Defenses of Aphid-Resistant Wheat Plants.

    Science.gov (United States)

    Sinha, Deepak K; Chandran, Predeesh; Timm, Alicia E; Aguirre-Rojas, Lina; Smith, C Michael

    2016-01-01

    The Russian wheat aphid, Diuraphis noxia, an invasive phytotoxic pest of wheat, Triticum aestivum, and barley, Hordeum vulgare, causes huge economic losses in Africa, South America, and North America. Most acceptable and ecologically beneficial aphid management strategies include selection and breeding of D. noxia-resistant varieties, and numerous D. noxia resistance genes have been identified in T. aestivum and H. vulgare. North American D. noxia biotype 1 is avirulent to T. aestivum varieties possessing Dn4 or Dn7 genes, while biotype 2 is virulent to Dn4 and avirulent to Dn7. The current investigation utilized next-generation RNAseq technology to reveal that biotype 2 over expresses proteins involved in calcium signaling, which activates phosphoinositide (PI) metabolism. Calcium signaling proteins comprised 36% of all transcripts identified in the two D. noxia biotypes. Depending on plant resistance gene-aphid biotype interaction, additional transcript groups included those involved in tissue growth; defense and stress response; zinc ion and related cofactor binding; and apoptosis. Activation of enzymes involved in PI metabolism by D. noxia biotype 2 aphids allows depletion of plant calcium that normally blocks aphid feeding sites in phloem sieve elements and enables successful, continuous feeding on plants resistant to avirulent biotype 1. Inhibition of the key enzyme phospholipase C significantly reduced biotype 2 salivation into phloem and phloem sap ingestion. PMID:26815857

  8. Infestation and natural parasitism of aphids in single and mixed pastures of black oats and ryegrass

    Directory of Open Access Journals (Sweden)

    Vinícius Soares Sturza

    2012-09-01

    Full Text Available Some species of aphids are major pests on cereal crops and grass pastures. Usually these pests are not adequately controlled in pasture lands that become sources of aphid infestations to cereal crops. The dynamics of aphids and the incidence of natural enemies are less known in pasture systems than in cereal fields. The objective of this work was to assess the aphid infestation and natural aphid parasitism in different pasture composition. Three hypotheses were tested: 1- the aphid species composition in pastures may vary according to the cereal species in the field; 2- the mixture of two plant species can modify the amount and diversity of aphids; 3- the plant species composition of pasture fields influences the parasitism of aphids. Empirical data were obtained from three Poaceae fields: black oats (Avena strigosa L., ryegrass (Lolium multiflorum L., and a mixed field of black oats and ryegrass. The most abundant aphid species was Rhopalosiphum padi followed by Sitobion avenae. Plant species composition increases the amount and the parasitism rates of aphids. The mixture of heavily infested black oats with a poorly infested ryegrass resulted in reduction of aphid infestation in comparison with heavily-infested single plant species field. This is possible because the conditions are favorable for the development of parasitoid populations. Aphidius colemani was the main parasitoid found in these areas.

  9. Olfactory responses of Aphidius gifuensis to odors of host plants and aphid-plant complexes

    Institute of Scientific and Technical Information of China (English)

    Song Yang; Rui Xu; Shuo-Yuan Yang; Rong-Ping Kuang

    2009-01-01

    The olfactory responses of Aphidius gifuensis to odors from two host plants (Nicotiana tabacum and Brassica napus ssp.) and their complexes with different infestation levels of two host aphids (Myzus persicae and Lipaphis erysimi) were respectively examined in an olfactometer. The results showed that female A. gifuensis did not respond to odors of undamaged or mechanically damaged host plants, but significantly responded to odors of aphid/plant complexes. Moreover, A. gifuensis responded significantly to odors of both M persicae and L. erysimi/plant complexes when host plants were infested by high levels of aphids, suggesting that quantity of aphid-induced volatiles could be important for attracting A. gifuensis. When tested between aphid/plant complexes, A. gifuensis did not show its preference for either complex. The efficiency of A. gifuensis against aphids in open fields potentially could be improved by using its olfactory response to aphid/plant complexes.

  10. The fungal endophyte Chaetomium globosum negatively affects both above- and belowground herbivores in cotton.

    Science.gov (United States)

    Zhou, Wenqing; Starr, James L; Krumm, Janice L; Sword, Gregory A

    2016-10-01

    Mutualistic plant-endophyte symbioses can benefit plants by increasing host fitness through reductions in herbivory. The fungus, Chaetomium globosum strain TAMU 520, was previously isolated as an endophyte from cotton (Gossypium hirsutum) and can be re-inoculated to systemically colonize cotton plants via seed treatment. We evaluated the potential impacts of the endophyte in cotton on plant parasitic nematodes belowground, along with piercing-sucking and chewing insects aboveground. Endophytic C. globosum inhibited root-knot nematode (Meloidogyne incognita) infection and reduced female reproduction belowground. To confirm the endophytic effect of C. globosum on root-knot nematode, a contact fungicide was applied to remove soil-borne and epiphytic C. globosum Consistent inhibition of nematode activity was observed post-fungicide treatment, with positive C. globosum colonization confirmed within plant tissues. Aboveground, endophytic C. globosum also negatively affected the fecundity of both cotton aphids (Aphis gossypii) and beet armyworms (Spodoptera exigua). Faster development rates and smaller head capsule of beet armyworm larvae were observed when fed Chaetomium-colonized plants. However, no larval weight difference was found between Chaetomium-colonized and control plants. No consistent effect on plant performance was found across experiments. Our findings illustrate how a single facultative fungal endophyte can increase plant systemic resistance against a range of invertebrate herbivores in a major crop. PMID:27451418

  11. 42 CFR 35.52 - Delivery of possession only; title unaffected.

    Science.gov (United States)

    2010-10-01

    ... 42 Public Health 1 2010-10-01 2010-10-01 false Delivery of possession only; title unaffected. 35... Patients § 35.52 Delivery of possession only; title unaffected. Except for delivery of effects to... possession and is not intended to affect in any manner the title to such money, effects, or proceeds....

  12. Host-plant-mediated effects of Nadefensin on herbivore and pathogen resistance in Nicotiana attenuata

    Directory of Open Access Journals (Sweden)

    Baldwin Ian T

    2008-10-01

    Full Text Available Abstract Background The adage from Shakespeare, "troubles, not as single spies, but in battalions come," holds true for Nicotiana attenuata, which is commonly attacked by both pathogens (Pseudomonas spp. and herbivores (Manduca sexta in its native habitats. Defense responses targeted against the pathogens can directly or indirectly influence the responses against the herbivores. Nadefensin is an effective induced defense gene against the bacterial pathogen Pseudomonas syringae pv tomato (PST DC3000, which is also elicited by attack from M. sexta larvae, but whether this defense protein influences M. sexta's growth and whether M. sexta-induced Nadefensin directly or indirectly influences PST DC3000 resistance are unknown. Results M. sexta larvae consumed less on WT and on Nadefensin-silenced N. attenuata plants that had previously been infected with PST DC3000 than on uninfected plants. WT plants infected with PST DC3000 showed enhanced resistance to PST DC3000 and decreased leaf consumption by M. sexta larvae, but larval mass gain was unaffected. PST DC3000-infected Nadefensin-silenced plants were less resistant to subsequent PST DC3000 challenge, and on these plants, M. sexta larvae consumed less and gained less mass. WT and Nadefensin-silenced plants previously damaged by M. sexta larvae were better able to resist subsequent PST DC3000 challenges than were undamaged plants. Conclusion These results demonstrate that Na-defensin directly mediates defense against PST DC3000 and indirectly against M. sexta in N. attenuata. In plants that were previously infected with PST DC3000, the altered leaf chemistry in PST DC3000-resistant WT plants and PST DC3000-susceptible Nadefensin-silenced plants differentially reduced M. sexta's leaf consumption and mass gain. In plants that were previously damaged by M. sexta, the combined effect of the altered host plant chemistry and a broad spectrum of anti-herbivore induced metabolomic responses was more

  13. 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

  14. Alien interference: disruption of infochemical networks by invasive insect herbivores.

    Science.gov (United States)

    Desurmont, Gaylord A; Harvey, Jeff; van Dam, Nicole M; Cristescu, Simona M; Schiestl, Florian P; Cozzolino, Salvatore; Anderson, Peter; Larsson, Mattias C; Kindlmann, Pavel; Danner, Holger; Turlings, Ted C J

    2014-08-01

    Insect herbivores trigger various biochemical changes in plants, and as a consequence, affect other organisms that are associated with these plants. Such plant-mediated indirect effects often involve herbivore-induced plant volatiles (HIPVs) that can be used as cues for foraging herbivores and their natural enemies, and are also known to affect pollinator attraction. In tightly co-evolved systems, the different trophic levels are expected to display adaptive response to changes in HIPVs caused by native herbivores. But what if a new herbivore invades such a system? Current literature suggests that exotic herbivores have the potential to affect HIPV production, and that plant responses to novel herbivores are likely to depend on phylogenetic relatedness between the invader and the native species. Here we review the different ways exotic herbivores can disrupt chemically mediated interactions between plants and the key users of HIPVs: herbivores, pollinators, and members of the third (i.e. predators and parasitoids) and fourth (i.e. hyperparasitoids) trophic levels. Current theory on insect invasions needs to consider that disruptive effects of invaders on infochemical networks can have a short-term impact on the population dynamics of native insects and plants, as well as exerting potentially negative consequences for the functioning of native ecosystems.

  15. Optimal control and cold war dynamics between plant and herbivore.

    Science.gov (United States)

    Low, Candace; Ellner, Stephen P; Holden, Matthew H

    2013-08-01

    Herbivores eat the leaves that a plant needs for photosynthesis. However, the degree of antagonism between plant and herbivore may depend critically on the timing of their interactions and the intrinsic value of a leaf. We present a model that investigates whether and when the timing of plant defense and herbivore feeding activity can be optimized by evolution so that their interactions can move from antagonistic to neutral. We assume that temporal changes in environmental conditions will affect intrinsic leaf value, measured as potential carbon gain. Using optimal-control theory, we model herbivore evolution, first in response to fixed plant strategies and then under coevolutionary dynamics in which the plant also evolves in response to the herbivore. In the latter case, we solve for the evolutionarily stable strategies of plant defense induction and herbivore hatching rate under different ecological conditions. Our results suggest that the optimal strategies for both plant and herbivore are to avoid direct conflict. As long as the plant has the capability for moderately lethal defense, the herbivore will modify its hatching rate to avoid plant defenses, and the plant will never have to use them. Insights from this model offer a possible solution to the paradox of sublethal defenses and provide a mechanism for stable plant-herbivore interactions without the need for natural enemy control.

  16. 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)

    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., ...

  17. 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...

  18. Dropping Behavior in the Pea Aphid (Hemiptera: Aphididae): How Does Environmental Context Affect Antipredator Responses?

    Science.gov (United States)

    Harrison, Katharine V; Preisser, Evan L

    2016-01-01

    The pea aphid Acyrthosiphon pisum : Harris (Hemiptera: Aphididae) is a phloem-feeding insect whose antipredator defenses include kicking, walking away, and dropping from the plant. Aphid dropping, a risky and energetically costly antipredator behavior, can be increased by the release of aphid alarm pheromone; there is also evidence that insect density and plant health can affect the likelihood of aphids engaging in this behavior. We investigated whether interactions between alarm cues, insect density, and plant health can alter the dropping behavior of aphids in response to an artificial disturbance. The presence of the alarm pheromone E-β-farnesene resulted in a nearly 15-fold increase in aphid dropping behavior; the other two factors, however, did not affect dropping and none of the two- or three-way interactions were significant. This was surprising because aphids affected plant health: production of new plant biomass after 5 d of exposure to high aphid densities was 50% lower than in the control treatment. This research adds to our understanding of the factors affecting aphid antipredator behavior; the fact that neither aphid density nor feeding period impacted dropping may reflect the high energetic costs of this activity and an unwillingness to use it in any but the riskiest situations. PMID:27638950

  19. High susceptibility of Bt maize to aphids enhances the performance of parasitoids of lepidopteran pests.

    Directory of Open Access Journals (Sweden)

    Cristina A Faria

    Full Text Available Concerns about possible undesired environmental effects of transgenic crops have prompted numerous evaluations of such crops. So-called Bt crops receive particular attention because they carry bacteria-derived genes coding for insecticidal proteins that might negatively affect non-target arthropods. Here we show a remarkable positive effect of Bt maize on the performance of the corn leaf aphid Rhopalosiphum maidis, which in turn enhanced the performance of parasitic wasps that feed on aphid honeydew. Within five out of six pairs that were evaluated, transgenic maize lines were significantly more susceptible to aphids than their near-isogenic equivalents, with the remaining pair being equally susceptible. The aphids feed from the phloem sieve element content and analyses of this sap in selected maize lines revealed marginally, but significantly higher amino acid levels in Bt maize, which might partially explain the observed increased aphid performance. Larger colony densities of aphids on Bt plants resulted in an increased production of honeydew that can be used as food by beneficial insects. Indeed, Cotesia marginiventris, a parasitoid of lepidopteran pests, lived longer and parasitized more pest caterpillars in the presence of aphid-infested Bt maize than in the presence of aphid-infested isogenic maize. Hence, depending on aphid pest thresholds, the observed increased susceptibility of Bt maize to aphids may be either a welcome or an undesirable side effect.

  20. Associations of wheat with pea can reduce aphid infestations.

    Science.gov (United States)

    Lopes, T; Bodson, B; Francis, F

    2015-06-01

    Increasing plant diversity within crops can be beneficial for pest control. In this field study, the effects of two wheat and pea associations (mixed cropping and strip cropping) on aphid populations were compared with pure stands of both crops by observations on tillers and plants. Pea was more susceptible to infestations than wheat. As expected, the density of aphid colonies was significantly higher in pure stands during the main occurrence periods, compared with associations. Additionally, flying beneficials, such as not only aphidophagous adult ladybirds but also parasitoid, hoverfly and lacewing species that feed on aphids at the larval stage, were monitored using yellow pan traps. At specific times of the sampling season, ladybirds and hoverflies were significantly more abundant in the pure stand of pea and wheat, respectively, compared with associations. Few parasitoids and lacewings were trapped. This study showed that increasing plant diversity within crops by associating cultivated species can reduce aphid infestations, since host plants are more difficult to locate. However, additional methods are needed to attract more efficiently adult beneficials into wheat and pea associations. PMID:26013274

  1. Sugarcane aphid resistance in sorghum and a host range

    Science.gov (United States)

    The sugarcane aphid (SCA), Melanaphis sacchari, has been present in the United States primarily on sugarcane in Florida, Hawaii, and Louisiana until 2013 where it was found on grain sorghum near Beaumont, Texas. Since 2013, the SCA has been rapidly spreading and overwintering. Depending on the plant...

  2. Sugarcane aphid in Oklahoma: Responding to a new pest

    Science.gov (United States)

    The sugarcane aphid (SCA) was first found in Oklahoma in 2013, and quickly became a major threat to grain sorghum production. Scientists at Oklahoma State University and the USDA's Wheat, Peanut and Other Field Crops Research Lab in Stillwater, working with cooperators in other sorghum producing st...

  3. Catalog of the Aphid Genera Described from the New World

    Science.gov (United States)

    This manuscript presents a synthesis and catalogue of the genera of New World aphids (sensu stricto) from 1758 to 2004. It includes information on 215 generic and subgeneric names, type localities, bibliographic information, etymology, as well as synonymic and other nomenclatural data. Two nomencl...

  4. Differential effects of weather and natural enemies on coexisting aphid populations.

    Science.gov (United States)

    Alyokhin, Andrei; Drummond, Francis A; Sewell, Gary; Storch, Richard H

    2011-06-01

    Study of mechanisms responsible for regulating populations of living organisms is essential for a better comprehension of the structure of biological communities and evolutionary forces in nature. Aphids (Hemiptera: Sternorrhyncha) comprise a large and economically important group of phytophagous insects distributed worldwide. Previous studies determined that density-dependent mechanisms play an important role in regulating their populations. However, only a few of those studies identified specific factors responsible for the observed regulation. Time series data used in this study originated from the untreated control plots that were a part of potato (Solanum tuberosum L.) insecticide trials in northern Maine from 1971 to 2004. The data set contained information on population densities of three potato-colonizing aphid species (buckthorn aphid, Aphis nasturtii; potato aphid, Macrosiphum euphorbiae; and green peach aphid, Myzus persicae) and their natural enemies. We used path analysis to explore effects of weather and natural enemies on the intrinsic growth rates of aphid populations. Weather factors considered in our analyses contributed to the regulation of aphid populations, either directly or through natural enemies. However, direct weather effects were in most cases detectable only at P ≤ 0.10. Potato aphids were negatively affected by both fungal disease and predators, although buckthorn aphids were negatively affected by predators only. Parasitoids did not have a noticeable effect on the growth of any of the three aphid species. Growth of green peach aphid populations was negatively influenced by interspecific interactions with the other two aphid species. Differential population regulation mechanisms detected in the current study might at least partially explain coexistence of three ecologically similar aphid species sharing the same host plant.

  5. [Population dynamics and control techniques of aphids on honeysuckle].

    Science.gov (United States)

    Sun, Ying; Xue, Ming; Zhang, Xiao; Zhao, Hai-Peng; Li, Zhao-Xia

    2013-11-01

    The objective of this study is to define the population dynamics of Semiaphis heraclei in the main-producing district of Lonicera japonica in Shandong, and screen for highly efficient, safety control technique. Through fixed field investigation, we tested the toxicity of eight kinds of insecticides by using dipping methods, and carried out the field experiment. The results showed that the aphids' emergence peak appeared in May. The aphids on the Sijihua variety of L. japonica was more susceptible and the peak was also seven days earlier than Damao variety of L. japonica. The aphid populations on Sijihua were 1 fold than those on the Daomao in happened peak. Comparing the eight kinds of insecticides, the LC50 of lambda-cyhaothrin, abamectin, imidacloprid and pyrethrin to wingless aphids were 1.494, 1.690, 2.840, 2.861 mg x L(-1), respectively, whose toxicity were higher, the toxicity of matrine, pymetrozine and azadirachtin were also high. The field efficacy trials indicated that during the period of aphids occurred, 25% imidacloprid wettable powder, 1.8% abamectin missible oil, 2.5% lambda-cyhaothrin missible oil, 25% pymetrozine wettable powder, 5% pyrethrin missible oil, 1% matrine water aqua were sprayed at concentrations of 20,000, 2,000, 2,500, 5,000, 500 and 50 times, respectively,the control effect achieved 91.69%, 98.90%, 96.18%, 95.06%, 99.24%, 90.10%, respectively, after 5 days. During the growing period of L. japonica in spring, application of thiamethoxam, thiacloprid, pymetrozine and imidacloprid, all of the control effect against aphids achieved above 98.88% after 50 days. The result indicated that May was the S. heraclei Takahashi's emergence peak in Pingyi, Shandong. The efficient safety and environmentally friendly insecticides by spraying and systemic insecticide of pymetrozine and imidacloprid by root application were all efficient controlled aphids. These insecticides were long for controlling S. heraclei Takahashi and worthy of being widely

  6. Circulative Nonpropagative Aphid Transmission of Nanoviruses: an Oversimplified View

    Science.gov (United States)

    Sicard, Anne; Zeddam, Jean-Louis; Yvon, Michel; Michalakis, Yannis; Gutiérrez, Serafin

    2015-01-01

    ABSTRACT Plant virus species of the family Nanoviridae have segmented genomes with the highest known number of segments encapsidated individually. They thus likely represent the most extreme case of the so-called multipartite, or multicomponent, viruses. All species of the family are believed to be transmitted in a circulative nonpropagative manner by aphid vectors, meaning that the virus simply crosses cellular barriers within the aphid body, from the gut to the salivary glands, without replicating or even expressing any of its genes. However, this assumption is largely based on analogy with the transmission of other plant viruses, such as geminiviruses or luteoviruses, and the details of the molecular and cellular interactions between aphids and nanoviruses are poorly investigated. When comparing the relative frequencies of the eight genome segments in populations of the species Faba bean necrotic stunt virus (FBNSV) (genus Nanovirus) within host plants and within aphid vectors fed on these plants, we unexpectedly found evidence of reproducible changes in the frequencies of some specific segments. We further show that these changes occur within the gut during early stages of the virus cycle in the aphid and not later, when the virus is translocated into the salivary glands. This peculiar observation, which was similarly confirmed in three aphid vector species, Acyrthosiphon pisum, Aphis craccivora, and Myzus persicae, calls for revisiting of the mechanisms of nanovirus transmission. It reveals an unexpected intimate interaction that may not fit the canonical circulative nonpropagative transmission. IMPORTANCE A specific mode of interaction between viruses and arthropod vectors has been extensively described in plant viruses in the three families Luteoviridae, Geminiviridae, and Nanoviridae, but never in arboviruses of animals. This so-called circulative nonpropagative transmission contrasts with the classical biological transmission of animal arboviruses in that

  7. High throughput phenotyping for aphid resistance in large plant collections

    Directory of Open Access Journals (Sweden)

    Chen Xi

    2012-08-01

    Full Text Available Abstract Background Phloem-feeding insects are among the most devastating pests worldwide. They not only cause damage by feeding from the phloem, thereby depleting the plant from photo-assimilates, but also by vectoring viruses. Until now, the main way to prevent such problems is the frequent use of insecticides. Applying resistant varieties would be a more environmental friendly and sustainable solution. For this, resistant sources need to be identified first. Up to now there were no methods suitable for high throughput phenotyping of plant germplasm to identify sources of resistance towards phloem-feeding insects. Results In this paper we present a high throughput screening system to identify plants with an increased resistance against aphids. Its versatility is demonstrated using an Arabidopsis thaliana activation tag mutant line collection. This system consists of the green peach aphid Myzus persicae (Sulzer and the circulative virus Turnip yellows virus (TuYV. In an initial screening, with one plant representing one mutant line, 13 virus-free mutant lines were identified by ELISA. Using seeds produced from these lines, the putative candidates were re-evaluated and characterized, resulting in nine lines with increased resistance towards the aphid. Conclusions This M. persicae-TuYV screening system is an efficient, reliable and quick procedure to identify among thousands of mutated lines those resistant to aphids. In our study, nine mutant lines with increased resistance against the aphid were selected among 5160 mutant lines in just 5 months by one person. The system can be extended to other phloem-feeding insects and circulative viruses to identify insect resistant sources from several collections, including for example genebanks and artificially prepared mutant collections.

  8. Differential reactions of soybean isolines with combinations of aphid resistance genes Rag1, Rag2, and Rag3 to four soybean aphid biotypes

    Science.gov (United States)

    With the discovery of the soybean aphid (Aphis glycines Matsumura) as a devastating insect pest of soybean (Glycine max (L.) Merr.) in the United States, host resistance was recognized as an important management option. However, the identification of soybean aphid isolates exhibiting strong virulenc...

  9. Transcriptomic responses of the aphid Myzus persicae nicotianae Blackman (Hemiptera: Aphididae to insecticides: Analyses in the single Chilean clone of the tobacco aphid

    Directory of Open Access Journals (Sweden)

    Marco Cabrera-Brandt

    2014-04-01

    Full Text Available The tobacco aphid Myzus persicae nicotianae Blackman is a subspecies of the highly polyphagous and agricultural pest Myzus persicae (Sulzer. For its control, insecticide applications are widely used, but resistance to numerous molecules has been reported, displaying at least three insecticide resistance mechanisms, including: (i elevated carboxylesterases (E-Carb, (ii modification of the acetylcholinesterase (MACE, and (iii kdr and super-kdr insensitivity mutations. In Chile, populations of the tobacco aphid are characterized by the presence of a single predominant clone, which is also present in high proportions in other countries of the Americas. This aphid clone exhibits low levels of carboxylesterase activity and is kdr susceptible, but the MACE mechanism of insecticide resistance has not been studied. In order to characterize the tobacco aphid in terms of the MACE mechanism and to identify a preliminary group of aphid genes putatively involved in insecticide resistance, a cDNA microarray was used to study the transcriptomic responses when aphids are sprayed with a carbamate insecticide. The single Chilean clone of the tobacco aphid was characterized as MACE susceptible, but we found 38 transcripts significantly regulated by insecticide exposure (13 up- and 25 down-regulated genes. The expression of six of them was validated by qRT-PCR experiments at several time points (6, 12, 18, 24, 30, 36, and 42 h after insecticide application. This mutational and transcriptomic characterization of the tobacco aphid responding to insecticide spray opens new hypotheses in the understanding of the molecular mechanisms underlying insecticide resistance.

  10. Gene expression analysis of parthenogenetic embryonic development of the pea aphid, Acyrthosiphon pisum, suggests that aphid parthenogenesis evolved from meiotic oogenesis.

    Directory of Open Access Journals (Sweden)

    Dayalan G Srinivasan

    Full Text Available Aphids exhibit a form of phenotypic plasticity, called polyphenism, in which genetically identical females reproduce sexually during one part of the life cycle and asexually (via parthenogenesis during the remainder of the life cycle. The molecular basis for aphid parthenogenesis is unknown. Cytological observations of aphid parthenogenesis suggest that asexual oogenesis evolved either through a modification of meiosis or from a mitotic process. As a test of these alternatives, we assessed the expression levels and expression patterns of canonical meiotic recombination and germline genes in the sexual and asexual ovaries of the pea aphid, Acyrthosiphon pisum. We observed expression of all meiosis genes in similar patterns in asexual and sexual ovaries, with the exception that some genes encoding Argonaute-family members were not expressed in sexual ovaries. In addition, we observed that asexual aphid tissues accumulated unspliced transcripts of Spo11, whereas sexual aphid tissues accumulated primarily spliced transcripts. In situ hybridization revealed Spo11 transcript in sexual germ cells and undetectable levels of Spo11 transcript in asexual germ cells. We also found that an obligately asexual strain of pea aphid produced little spliced Spo11 transcript. Together, these results suggest that parthenogenetic oogenesis evolved from a meiosis-like, and not a mitosis-like, process and that the aphid reproductive polyphenism may involve a modification of Spo11 gene activity.

  11. Plant-herbivore interactions mediated by plant toxicity

    Science.gov (United States)

    Feng, Z.; Liu, R.; DeAngelis, D.L.

    2008-01-01

    We explore the impact of plant toxicity on the dynamics of a plant-herbivore interaction, such as that of a mammalian browser and its plant forage species, by studying a mathematical model that includes a toxin-determined functional response. In this functional response, the traditional Holling Type 2 response is modified to include the negative effect of toxin on herbivore growth, which can overwhelm the positive effect of biomass ingestion at sufficiently high plant toxicant concentrations. Two types of consumption decisions of the herbivore are considered. One of these (Case 1) incorporates the adaptation of the herbivore to control its rate of consumption of plant items when that is likely to lead to levels of toxicity that more than offset the marginal gain to the herbivore of consuming more plant biomass, while the other (Case 2) simply assumes that, although the herbivore's rate of ingestion of plant biomass is negatively affected by increasing ingestion of toxicant relative to the load it can safely deal with, the herbivore is not able to prevent detrimental or even lethal levels of toxicant intake. A primary result of this work is that these differences in behavior lead to dramatically different outcomes, summarized in bifurcation diagrams. In Case 2, a wide variety of dynamics may occur due to the interplay of Holling Type 2 dynamics and the effect of the plant toxicant. These dynamics include the occurrence of bistability, in which both a periodic solution and the herbivore-extinction equilibrium are attractors, as well the possibility of a homoclinic bifurcation. Whether the herbivore goes to extinction in the bistable case depends on initial conditions of herbivore and plant biomasses. For relatively low herbivore resource acquisition rates, the toxicant effect increases the likelihood of 'paradox of enrichment' type limit cycle oscillations, but at higher resource acquisition rates, the toxicant may decrease the likelihood of these cycles. ?? 2007

  12. 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...... C. obscurus and N. fresenii were sporadically present on a limited number of aphid species. This study is the first survey on ecological host range of entomophthoralean fungi in Tunisia, and the first documentation of C. obscurus and N. fresenii to occur in Tunisia and Maghreb Region....

  13. 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.

  14. Enhanced ERPs to visual stimuli in unaffected male siblings of ASD children.

    Science.gov (United States)

    Anzures, Gizelle; Goyet, Louise; Ganea, Natasa; Johnson, Mark H

    2016-01-01

    Autism spectrum disorders are characterized by deficits in social and communication abilities. While unaffected relatives lack severe deficits, milder impairments have been reported in some first-degree relatives. The present study sought to verify whether mild deficits in face perception are evident among the unaffected younger siblings of children with ASD. Children between 6-9 years of age completed a face-recognition task and a passive viewing ERP task with face and house stimuli. Sixteen children were typically developing with no family history of ASD, and 17 were unaffected children with an older sibling with ASD. Findings indicate that, while unaffected siblings are comparable to controls in their face-recognition abilities, unaffected male siblings in particular show relatively enhanced P100 and P100-N170 peak-to-peak amplitude responses to faces and houses. Enhanced ERPs among unaffected male siblings is discussed in relation to potential differences in neural network recruitment during visual and face processing. PMID:25506753

  15. Metabolite Profiling Reveals a Specific Response in Tomato to Predaceous Chrysoperla carnea Larvae and Herbivore(s)-Predator Interactions with the Generalist Pests Tetranychus urticae and Myzus persicae.

    Science.gov (United States)

    Errard, Audrey; Ulrichs, Christian; Kühne, Stefan; Mewis, Inga; Mishig, Narantuya; Maul, Ronald; Drungowski, Mario; Parolin, Pia; Schreiner, Monika; Baldermann, Susanne

    2016-01-01

    The spider mite Tetranychus urticae Koch and the aphid Myzus persicae (Sulzer) both infest a number of economically significant crops, including tomato (Solanum lycopersicum). Although used for decades to control pests, the impact of green lacewing larvae Chrysoperla carnea (Stephens) on plant biochemistry was not investigated. Here, we used profiling methods and targeted analyses to explore the impact of the predator and herbivore(s)-predator interactions on tomato biochemistry. Each pest and pest-predator combination induced a characteristic metabolite signature in the leaf and the fruit thus, the plant exhibited a systemic response. The treatments had a stronger impact on non-volatile metabolites including abscisic acid and amino acids in the leaves in comparison with the fruits. In contrast, the various biotic factors had a greater impact on the carotenoids in the fruits. We identified volatiles such as myrcene and α-terpinene which were induced by pest-predator interactions but not by single species, and we demonstrated the involvement of the phytohormone abscisic acid in tritrophic interactions for the first time. More importantly, C. carnea larvae alone impacted the plant metabolome, but the predator did not appear to elicit particular defense pathways on its own. Since the presence of both C. carnea larvae and pest individuals elicited volatiles which were shown to contribute to plant defense, C. carnea larvae could therefore contribute to the reduction of pest infestation, not only by its preying activity, but also by priming responses to generalist herbivores such as T. urticae and M. persicae. On the other hand, the use of C. carnea larvae alone did not impact carotenoids thus, was not prejudicial to the fruit quality. The present piece of research highlights the specific impact of predator and tritrophic interactions with green lacewing larvae, spider mites, and aphids on different components of the tomato primary and secondary metabolism for the first

  16. Metabolite Profiling Reveals a Specific Response in Tomato to Predaceous Chrysoperla carnea Larvae and Herbivore(s)-Predator Interactions with the Generalist Pests Tetranychus urticae and Myzus persicae.

    Science.gov (United States)

    Errard, Audrey; Ulrichs, Christian; Kühne, Stefan; Mewis, Inga; Mishig, Narantuya; Maul, Ronald; Drungowski, Mario; Parolin, Pia; Schreiner, Monika; Baldermann, Susanne

    2016-01-01

    The spider mite Tetranychus urticae Koch and the aphid Myzus persicae (Sulzer) both infest a number of economically significant crops, including tomato (Solanum lycopersicum). Although used for decades to control pests, the impact of green lacewing larvae Chrysoperla carnea (Stephens) on plant biochemistry was not investigated. Here, we used profiling methods and targeted analyses to explore the impact of the predator and herbivore(s)-predator interactions on tomato biochemistry. Each pest and pest-predator combination induced a characteristic metabolite signature in the leaf and the fruit thus, the plant exhibited a systemic response. The treatments had a stronger impact on non-volatile metabolites including abscisic acid and amino acids in the leaves in comparison with the fruits. In contrast, the various biotic factors had a greater impact on the carotenoids in the fruits. We identified volatiles such as myrcene and α-terpinene which were induced by pest-predator interactions but not by single species, and we demonstrated the involvement of the phytohormone abscisic acid in tritrophic interactions for the first time. More importantly, C. carnea larvae alone impacted the plant metabolome, but the predator did not appear to elicit particular defense pathways on its own. Since the presence of both C. carnea larvae and pest individuals elicited volatiles which were shown to contribute to plant defense, C. carnea larvae could therefore contribute to the reduction of pest infestation, not only by its preying activity, but also by priming responses to generalist herbivores such as T. urticae and M. persicae. On the other hand, the use of C. carnea larvae alone did not impact carotenoids thus, was not prejudicial to the fruit quality. The present piece of research highlights the specific impact of predator and tritrophic interactions with green lacewing larvae, spider mites, and aphids on different components of the tomato primary and secondary metabolism for the first

  17. Metabolite profiling reveals a specific response in tomato to predaceous Chrysoperla carnea larvae and herbivore(s-predator interactions with the generalist pests Tetranychus urticae and Myzus persicae

    Directory of Open Access Journals (Sweden)

    Audrey Errard

    2016-08-01

    Full Text Available The spider mite Tetranychus urticae Koch and the aphid Myzus persicae (Sulzer both infest a number of economically significant crops, including tomato (Solanum lycopersicum. Although used for decades to control pests, the impact of green lacewing larvae Chrysoperla carnea (Stephens on plant biochemistry was not investigated. Here we used profiling methods and targeted analyses to explore the impact of the predator and herbivore(s-predator interactions on tomato biochemistry. Each pest and pest-predator combination induced a characteristic metabolite signature in the leaf and the fruit thus, the plant exhibited a systemic response. The treatments had a stronger impact on non-volatile metabolites including abscisic acid and amino acids in the leaves in comparison with the fruits. In contrast, the various biotic factors had a greater impact on the carotenoids in the fruits. We identified volatiles such as myrcene and α-terpinene which were induced by pest-predator interactions but not by single species, and we demonstrated the involvement of the phytohormone abscisic acid in tritrophic interactions for the first time. More importantly, C. carnea larvae alone impacted the plant metabolome, but the predator did not appear to elicit particular defense pathways on its own. Since the presence of both C. carnea larvae and pest individuals elicited volatiles which were shown to contribute to plant defense, C. carnea larvae could therefore contribute to the reduction of pest infestation, not only by its preying activity, but also by priming responses to generalist herbivores such as T. urticae and M. persicae. On the other hand, the use of C. carnea larvae alone did not impact carotenoids thus, was not prejudicial to the fruit quality. The present piece of research highlights the specific impact of predator and tritrophic interactions with green lacewing larvae, spider mites and aphids on different components of the tomato primary and secondary metabolism

  18. Metabolite Profiling Reveals a Specific Response in Tomato to Predaceous Chrysoperla carnea Larvae and Herbivore(s)-Predator Interactions with the Generalist Pests Tetranychus urticae and Myzus persicae

    Science.gov (United States)

    Errard, Audrey; Ulrichs, Christian; Kühne, Stefan; Mewis, Inga; Mishig, Narantuya; Maul, Ronald; Drungowski, Mario; Parolin, Pia; Schreiner, Monika; Baldermann, Susanne

    2016-01-01

    The spider mite Tetranychus urticae Koch and the aphid Myzus persicae (Sulzer) both infest a number of economically significant crops, including tomato (Solanum lycopersicum). Although used for decades to control pests, the impact of green lacewing larvae Chrysoperla carnea (Stephens) on plant biochemistry was not investigated. Here, we used profiling methods and targeted analyses to explore the impact of the predator and herbivore(s)-predator interactions on tomato biochemistry. Each pest and pest-predator combination induced a characteristic metabolite signature in the leaf and the fruit thus, the plant exhibited a systemic response. The treatments had a stronger impact on non-volatile metabolites including abscisic acid and amino acids in the leaves in comparison with the fruits. In contrast, the various biotic factors had a greater impact on the carotenoids in the fruits. We identified volatiles such as myrcene and α-terpinene which were induced by pest-predator interactions but not by single species, and we demonstrated the involvement of the phytohormone abscisic acid in tritrophic interactions for the first time. More importantly, C. carnea larvae alone impacted the plant metabolome, but the predator did not appear to elicit particular defense pathways on its own. Since the presence of both C. carnea larvae and pest individuals elicited volatiles which were shown to contribute to plant defense, C. carnea larvae could therefore contribute to the reduction of pest infestation, not only by its preying activity, but also by priming responses to generalist herbivores such as T. urticae and M. persicae. On the other hand, the use of C. carnea larvae alone did not impact carotenoids thus, was not prejudicial to the fruit quality. The present piece of research highlights the specific impact of predator and tritrophic interactions with green lacewing larvae, spider mites, and aphids on different components of the tomato primary and secondary metabolism for the first

  19. A Coevolutionary Arms Race: Understanding Plant-Herbivore Interactions

    Science.gov (United States)

    Becklin, Katie M.

    2008-01-01

    Plants and insects share a long evolutionary history characterized by relationships that affect individual, population, and community dynamics. Plant-herbivore interactions are a prominent feature of this evolutionary history; it is by plant-herbivore interactions that energy is transferred from primary producers to the rest of the food web. Not…

  20. Global environmental controls of diversity in large herbivores

    NARCIS (Netherlands)

    Olff, Han; Ritchie, Mark E.; Prins, Herbert H.T.

    2002-01-01

    Large mammalian herbivores occupy half of the earth's land surface and are important both ecologically and economically, but their diversity is threatened by human activities. We investigated how the diversity of large herbivores changes across gradients of global precipitation and soil fertility. H

  1. The global distribution of diet breadth in insect herbivores.

    Science.gov (United States)

    Forister, Matthew L; Novotny, Vojtech; Panorska, Anna K; Baje, Leontine; Basset, Yves; Butterill, Philip T; Cizek, Lukas; Coley, Phyllis D; Dem, Francesca; Diniz, Ivone R; Drozd, Pavel; Fox, Mark; Glassmire, Andrea E; Hazen, Rebecca; Hrcek, Jan; Jahner, Joshua P; Kaman, Ondrej; Kozubowski, Tomasz J; Kursar, Thomas A; Lewis, Owen T; Lill, John; Marquis, Robert J; Miller, Scott E; Morais, Helena C; Murakami, Masashi; Nickel, Herbert; Pardikes, Nicholas A; Ricklefs, Robert E; Singer, Michael S; Smilanich, Angela M; Stireman, John O; Villamarín-Cortez, Santiago; Vodka, Stepan; Volf, Martin; Wagner, David L; Walla, Thomas; Weiblen, George D; Dyer, Lee A

    2015-01-13

    Understanding variation in resource specialization is important for progress on issues that include coevolution, community assembly, ecosystem processes, and the latitudinal gradient of species richness. Herbivorous insects are useful models for studying resource specialization, and the interaction between plants and herbivorous insects is one of the most common and consequential ecological associations on the planet. However, uncertainty persists regarding fundamental features of herbivore diet breadth, including its relationship to latitude and plant species richness. Here, we use a global dataset to investigate host range for over 7,500 insect herbivore species covering a wide taxonomic breadth and interacting with more than 2,000 species of plants in 165 families. We ask whether relatively specialized and generalized herbivores represent a dichotomy rather than a continuum from few to many host families and species attacked and whether diet breadth changes with increasing plant species richness toward the tropics. Across geographic regions and taxonomic subsets of the data, we find that the distribution of diet breadth is fit well by a discrete, truncated Pareto power law characterized by the predominance of specialized herbivores and a long, thin tail of more generalized species. Both the taxonomic and phylogenetic distributions of diet breadth shift globally with latitude, consistent with a higher frequency of specialized insects in tropical regions. We also find that more diverse lineages of plants support assemblages of relatively more specialized herbivores and that the global distribution of plant diversity contributes to but does not fully explain the latitudinal gradient in insect herbivore specialization. PMID:25548168

  2. Comparative transcriptome analysis of Gossypium hirsutum L. in response to sap sucking insects: aphid and whitefly

    OpenAIRE

    Dubey, Neeraj Kumar; Goel, Ridhi; Ranjan, Alok; Idris, Asif; Singh, Sunil Kumar; Bag, Sumit K; Chandrashekar, Krishnappa; Pandey, Kapil Deo; Singh, Pradhyumna Kumar; Sawant, Samir V.

    2013-01-01

    Background Cotton (Gossypium hirsutum L.) is a major fiber crop that is grown worldwide; it faces extensive damage from sap-sucking insects, including aphids and whiteflies. Genome-wide transcriptome analysis was performed to understand the molecular details of interaction between Gossypium hirsutum L. and sap-sucking pests, namely Aphis gossypii (Aphid) and Bemisia tabacci (Whiteflies). Roche’s GS-Titanium was used to sequence transcriptomes of cotton infested with aphids and whiteflies for ...

  3. In vitro interactions of the aphid endosymbiotic SymL chaperonin with barley yellow dwarf virus.

    OpenAIRE

    Filichkin, S A; Brumfield, S; Filichkin, T P; Young, M. J.

    1997-01-01

    Barley yellow dwarf virus (BYDV)-vector relationships suggest that there are specific interactions between BYDV virions and the aphid's cellular components. However, little is known about vector factors that mediate virion recognition, cellular trafficking, and accumulation within the aphid. Symbionins are molecular chaperonins produced by intracellular endosymbiotic bacteria and are the most abundant proteins found in aphids. To elucidate the potential role of symbionins in BYDV transmission...

  4. Distribution, host plants and natural enemies of sugar beet root aphid (Pemphigus fuscicornis) In Slovakia

    OpenAIRE

    Tóth Peter; Tancik Ján I.; Tóthová Monika; Pačuta Vladimir

    2006-01-01

    During 2003-2004, field surveys were realized to observe the distribution of sugar beet aphid, Pemphigus fuscicornis (K o c h) (Sternorrhyncha Pemphigidae) in southwestern Slovakia. The research was carried out at 60 different localities with altitudes 112-220 m a. s. l. Sugar beet root aphid was recorded at 30 localities. The aphid was recorded in Slovakia for the first time, but its occurrence was predicted and symptoms and harmfulness overlooked by now. The presence of P. fuscicornis was i...

  5. Changes in the Russian Wheat Aphid (Hemiptera: Aphididae) Biotype Complex in South Africa.

    Science.gov (United States)

    Jankielsohn, Astrid

    2016-04-01

    Russian wheat aphid Diuraphis noxia (Kurdjumov) has spread from its native area in central Asia to all the major wheat-producing countries in the world to become an international wheat pest. Because the Russian wheat aphid is a serious threat to the wheat industry in South Africa, it is important to investigate the key factors involved in the distribution of Russian wheat aphid biotypes and in the changes of the Russian wheat aphid biotype complex in South Africa. There are currently four known Russian wheat aphid biotypes occurring in South Africa. Russian wheat aphid samples were collected from 2011 to 2014 during the wheat-growing season in spring and summer and these samples were screened to determine the biotype status. RWASA1 occurred predominantly in the Western Cape, while RWASA2 and RWASA3 occurred predominantly in the Eastern Free State. Following the first record of RWASA4 in 2011, this biotype was restricted to the Eastern Free State. The surveys suggest that the Russian wheat aphid bioype complex was more diverse in the Eastern Free State than in the other wheat production areas. There was also a shift in Russian wheat aphid biotype composition over time. The Russian wheat aphid biotype complex is dynamic, influenced by environmental factors such as host plants, altitude, and climate, and it can change and diversify over time causing fluctuation in populations over sites and years. This dynamic nature of the Russian wheat aphid will continue to challenge the development of Russian wheat aphid-resistant wheat cultivars in South Africa, and the continued monitoring of the biotypic and genetic structure, to determine genetic relatedness and variation in different biotypes, of Russian wheat aphid populations is important for protecting wheat.

  6. New additions and invasive aphids for Turkey’s aphidofauna (Hemiptera: Aphidoidea)

    OpenAIRE

    Şenol, Özhan; BEĞEN, Hayal AKYILDIRIM; Görür, Gazi; DEMİRTAŞ, Emin

    2015-01-01

    This study was carried out in order to determine aphid species in the Inner Western Anatolian Subregion of Turkey. Nineteen aphid species are reported as new to the Turkish aphid fauna. These species are Aphis eryngiiglomerata Bozhko, 1963; Aphis glareosae Bozhko, 1959; Capitophorus eniwanus Miyazaki, 1971; Chaitophorus indicus A.K. Ghosh, M.R. Ghosh & D.N. Raychaudhuri, 1970; Chaitophorus ramicola (Börner, 1949); Cinara indica Verma, 1970; Cinara juniperensis (Gillette & Palmer, 1925...

  7. New Additions and Invasive Aphids for Turkey’s Aphidofauna (Hemiptera: Aphidoidea)

    OpenAIRE

    Şenol, Özhan; Akyıldırım, Hayal; Görür, Gazi; Demirtaş, Emin

    2015-01-01

    This study was carried out in order to determine aphid species in the Inner Western Anatolian Subregion of Turkey. Nineteen aphid species are reported as new to the Turkish aphid fauna. These species are Aphis eryngiiglomerata Bozhko, 1963; Aphis glareosae Bozhko, 1959; Capitophorus eniwanus Miyazaki, 1971; Chaitophorus indicus A.K. Ghosh, M.R. Ghosh & D.N. Raychaudhuri, 1970; Chaitophorus ramicola (Börner, 1949); Cinara indica Verma, 1970; Cinara juniperensis (Gillette & Palmer, 1925); Cinar...

  8. Neonicotinoid Binding, Toxicity and Expression of Nicotinic Acetylcholine Receptor Subunits in the Aphid Acyrthosiphon pisum

    OpenAIRE

    Taillebois, Emiliane; Beloula, Abdelhamid; Quinchard, Sophie; Jaubert-Possamai, Stéphanie; Daguin, Antoine; Servent, Denis; Tagu, Denis; Thany, Steeve H.; Tricoire-Leignel, Helene

    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 ...

  9. Changes in the Russian Wheat Aphid (Hemiptera: Aphididae) Biotype Complex in South Africa.

    Science.gov (United States)

    Jankielsohn, Astrid

    2016-04-01

    Russian wheat aphid Diuraphis noxia (Kurdjumov) has spread from its native area in central Asia to all the major wheat-producing countries in the world to become an international wheat pest. Because the Russian wheat aphid is a serious threat to the wheat industry in South Africa, it is important to investigate the key factors involved in the distribution of Russian wheat aphid biotypes and in the changes of the Russian wheat aphid biotype complex in South Africa. There are currently four known Russian wheat aphid biotypes occurring in South Africa. Russian wheat aphid samples were collected from 2011 to 2014 during the wheat-growing season in spring and summer and these samples were screened to determine the biotype status. RWASA1 occurred predominantly in the Western Cape, while RWASA2 and RWASA3 occurred predominantly in the Eastern Free State. Following the first record of RWASA4 in 2011, this biotype was restricted to the Eastern Free State. The surveys suggest that the Russian wheat aphid bioype complex was more diverse in the Eastern Free State than in the other wheat production areas. There was also a shift in Russian wheat aphid biotype composition over time. The Russian wheat aphid biotype complex is dynamic, influenced by environmental factors such as host plants, altitude, and climate, and it can change and diversify over time causing fluctuation in populations over sites and years. This dynamic nature of the Russian wheat aphid will continue to challenge the development of Russian wheat aphid-resistant wheat cultivars in South Africa, and the continued monitoring of the biotypic and genetic structure, to determine genetic relatedness and variation in different biotypes, of Russian wheat aphid populations is important for protecting wheat. PMID:26803815

  10. Aphids (Homoptera, Aphidodea inhabiting the trees Crataegus x media Bechst. in the urban green area. Part II. Domination and frequency of aphids, their enemies and the damage caused by aphids

    Directory of Open Access Journals (Sweden)

    Aneta Sławińska

    2013-12-01

    Full Text Available The studies were conducted in Lublin in the years 1999-2001 in two sites (street and park ones on the trees Crataegus x inedia Bechst. The purpose was to determine the domination and frequency of particular aphid species, their effect on the decorative character of plants as well as the occurrence of the aphidophagous in aphid colonies. It was found out that A. pomi was the dominating species in both sites. The decorative character of the studied trees was lowered by aphids A. pomi and aphids from the genus Dysaphis. Aphids from the genus Dysaphis also caused changes in the chemical composition of the injured plant parts. The presence of predatory arthropods was observed in aphid colonies occurring on hawthorn. The most numerous of these were the larvae of Syrphidae and Coccinellidae. The culture of parasitized aphids gave numerous flights of parasitoids and hyperparasitoids. Greater number of both predators and parasitoids of I and II grades were observed in the street site as compared to the park site.

  11. Economy Unaffected

    Institute of Scientific and Technical Information of China (English)

    2015-01-01

    The recent stock market turbulence wil.t not have a major spil.tover effect on China's rear economg, global, rating agency Moody's said on Jury 16. The equity market turmoil, does not warrant a change in the agency's Fore-cast that China's rear economic growth will reach 6.5 to 7.5 percent this year and 6 to 7 percent in 2016, Moody's Investors Service said in a report.

  12. Modification of non-vector aphid feeding behavior on virus-infected host plant.

    Science.gov (United States)

    Hu, Zuqing; Zhao, Huiyan; Thieme, Thomas

    2013-01-01

    Virus-infected host plants can have positive, neutral or negative effects on vector aphids. Even though the proportion of non-vector aphids associated with a plant far exceeds that of vector species, little is known about the effect of virus-infected plants on non-vector aphids. In the present study, the English grain aphid Sitobion avenae (Fabricius) (Hemiptera: Aphididae), a non-vector of Wheat dwarf virus (WDV) and Cereal yellow dwarf virus-RPV (CYDV-RPV), was monitored on, virus-infected, virus-free and leafhopper/aphid-infested, and virus- and insect-free (control) barley, Hordeum vulgare L. (Poales: Poaceae), plants. Electrical penetration graph recordings were performed. Compared with the control plants, S. avenae on infected plants exhibited reduced non-probing and pathway phase, and increased phloem sap ingestion phase, and more aphids reached sustained phloem ingestion. However, the electrical penetration graph parameters described above showed no significant differences in aphid feeding behavior on virus-free and vector pre-infested plants and the control barley plants during S. avenae feeding. The results suggest that WDV/CYDV-RPV-infected host plants positively affected the feeding behavior of the non-vector aphid S. avenae. Based on these results, the reasons and trends among the virus-infected host plants' effects on the feeding behavior of non-vector aphids are discussed. PMID:23902296

  13. 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.

  14. Herbivore-induced plant responses in Brassica oleracea prevail over effects of constitutive resistance and result in enhanced herbivore attack

    NARCIS (Netherlands)

    Poelman, E.H.; Loon, van J.J.A.; Dam, van N.M.; Vet, L.E.M.; Dicke, M.

    2010-01-01

    2. Here we studied the effect of early-season herbivory by caterpillars of Pieris rapae on the composition of the insect herbivore community on domesticated Brassica oleracea plants. We compared the effect of herbivory on two cultivars that differ in the degree of susceptibility to herbivores to ana

  15. Treatment by glyphosate-based herbicide alters life history parameters of the rose-grain aphid Metopolophium dirhodum

    Science.gov (United States)

    Saska, Pavel; Skuhrovec, Jiří; Lukáš, Jan; Chi, Hsin; Tuan, Shu-Jen; Honěk, Alois

    2016-01-01

    Glyphosate is the number one herbicide in the world. We investigated the sub-lethal effects of this herbicide on the aphid Metopolophium dirhodum (Walker), using an age-stage, two-sex life table approach. Three concentrations of the herbicide (low - 33.5, medium - 66.9 and high - 133.8 mmol dm−3 of active ingredient) and distilled water as the control were used. The LC50 of the IPA salt of glyphosate on M. dirhodum was equivalent to 174.9 mmol dm−3 of the active ingredient (CI95: 153.0, 199.0). The population parameters were significantly negatively affected by herbicide application, and this negative effect was progressive with the increasing concentration of the herbicide. A difference of two orders of magnitude existed in the predicted population development of M. dirhodum between the high concentration of the herbicide and the control. This is the first study that comprehensively documents such a negative effect on the population of an herbivorous insect. PMID:27302015

  16. Cross-tolerance to biotic and abiotic stresses in plants: a focus on resistance to aphid infestation.

    Science.gov (United States)

    Foyer, Christine H; Rasool, Brwa; Davey, Jack W; Hancock, Robert D

    2016-03-01

    Plants co-evolved with an enormous variety of microbial pathogens and insect herbivores under daily and seasonal variations in abiotic environmental conditions. Hence, plant cells display a high capacity to respond to diverse stresses through a flexible and finely balanced response network that involves components such as reduction-oxidation (redox) signalling pathways, stress hormones and growth regulators, as well as calcium and protein kinase cascades. Biotic and abiotic stress responses use common signals, pathways and triggers leading to cross-tolerance phenomena, whereby exposure to one type of stress can activate plant responses that facilitate tolerance to several different types of stress. While the acclimation mechanisms and adaptive responses that facilitate responses to single biotic and abiotic stresses have been extensively characterized, relatively little information is available on the dynamic aspects of combined biotic/abiotic stress response. In this review, we consider how the abiotic environment influences plant responses to attack by phloem-feeding aphids. Unravelling the signalling cascades that underpin cross-tolerance to biotic and abiotic stresses will allow the identification of new targets for increasing environmental resilience in crops.

  17. Treatment by glyphosate-based herbicide alters life history parameters of the rose-grain aphid Metopolophium dirhodum

    Science.gov (United States)

    Saska, Pavel; Skuhrovec, Jiří; Lukáš, Jan; Chi, Hsin; Tuan, Shu-Jen; Honěk, Alois

    2016-06-01

    Glyphosate is the number one herbicide in the world. We investigated the sub-lethal effects of this herbicide on the aphid Metopolophium dirhodum (Walker), using an age-stage, two-sex life table approach. Three concentrations of the herbicide (low - 33.5, medium - 66.9 and high - 133.8 mmol dm‑3 of active ingredient) and distilled water as the control were used. The LC50 of the IPA salt of glyphosate on M. dirhodum was equivalent to 174.9 mmol dm‑3 of the active ingredient (CI95: 153.0, 199.0). The population parameters were significantly negatively affected by herbicide application, and this negative effect was progressive with the increasing concentration of the herbicide. A difference of two orders of magnitude existed in the predicted population development of M. dirhodum between the high concentration of the herbicide and the control. This is the first study that comprehensively documents such a negative effect on the population of an herbivorous insect.

  18. Treatment by glyphosate-based herbicide alters life history parameters of the rose-grain aphid Metopolophium dirhodum.

    Science.gov (United States)

    Saska, Pavel; Skuhrovec, Jiří; Lukáš, Jan; Chi, Hsin; Tuan, Shu-Jen; Honěk, Alois

    2016-01-01

    Glyphosate is the number one herbicide in the world. We investigated the sub-lethal effects of this herbicide on the aphid Metopolophium dirhodum (Walker), using an age-stage, two-sex life table approach. Three concentrations of the herbicide (low - 33.5, medium - 66.9 and high - 133.8 mmol dm(-3) of active ingredient) and distilled water as the control were used. The LC50 of the IPA salt of glyphosate on M. dirhodum was equivalent to 174.9 mmol dm(-3) of the active ingredient (CI95: 153.0, 199.0). The population parameters were significantly negatively affected by herbicide application, and this negative effect was progressive with the increasing concentration of the herbicide. A difference of two orders of magnitude existed in the predicted population development of M. dirhodum between the high concentration of the herbicide and the control. This is the first study that comprehensively documents such a negative effect on the population of an herbivorous insect. PMID:27302015

  19. Attention, memory and verbal learning and their relation to schizotypal traits in unaffected parents of schizophrenic patients

    OpenAIRE

    Beatriz Caparrós; Neus Barrantes-Vidal; Ferran Viñas; Jordi Obiols

    2007-01-01

    The main objective of this ex post facto study is to compare the differences in cognitive functions and their relation to schizotypal personality traits between a group of unaffected parents of schizophrenic patients and a control group. A total of 52 unaffected biological parents of schizophrenic patients and 52 unaffected parents of unaffected subjects were assessed in measures of attention (Continuous Performance Test- Identical Pairs Version, CPT-IP), memory and verbal learning (Californi...

  20. Genomic evidence for complementary purine metabolism in the pea aphid, Acyrthosiphon pisum, and its symbiotic bacterium Buchnera aphidicola.

    Science.gov (United States)

    Ramsey, J S; MacDonald, S J; Jander, G; Nakabachi, A; Thomas, G H; Douglas, A E

    2010-03-01

    The purine salvage pathway recycles purines to nucleotides, promoting efficient utilization of purine nucleotides. Exceptionally among animals with completely sequenced genomes, the pea aphid lacks key purine recycling genes that code for purine nucleoside phosphorylase and adenosine deaminase, indicating that the aphid can neither metabolize nucleosides to the corresponding purines, nor adenosine to inosine. Purine metabolism genes in the symbiotic bacterium Buchnera complement aphid genes, and Buchnera can meet its nucleotide requirement from aphid-derived guanosine. Buchnera demand for nucleosides may have relaxed the selection for purine recycling in the aphid, leading to the loss of key aphid purine salvage genes. Further, the coupled purine metabolism of aphid and Buchnera could contribute to the dependence of the pea aphid on this symbiosis.

  1. Herbivore preference for native vs. exotic plants: generalist herbivores from multiple continents prefer exotic plants that are evolutionarily naive.

    Directory of Open Access Journals (Sweden)

    Wendy E Morrison

    Full Text Available Enemy release and biotic resistance are competing, but not mutually exclusive, hypotheses addressing the success or failure of non-native plants entering a new region. Enemy release predicts that exotic plants become invasive by escaping their co-adapted herbivores and by being unrecognized or unpalatable to native herbivores that have not been selected to consume them. In contrast, biotic resistance predicts that native generalist herbivores will suppress exotic plants that will not have been selected to deter these herbivores. We tested these hypotheses using five generalist herbivores from North or South America and nine confamilial pairs of native and exotic aquatic plants. Four of five herbivores showed 2.4-17.3 fold preferences for exotic over native plants. Three species of South American apple snails (Pomacea sp. preferred North American over South American macrophytes, while a North American crayfish Procambarus spiculifer preferred South American, Asian, and Australian macrophytes over North American relatives. Apple snails have their center of diversity in South America, but a single species (Pomacea paludosa occurs in North America. This species, with a South American lineage but a North American distribution, did not differentiate between South American and North American plants. Its preferences correlated with preferences of its South American relatives rather than with preferences of the North American crayfish, consistent with evolutionary inertia due to its South American lineage. Tests of plant traits indicated that the crayfish responded primarily to plant structure, the apple snails primarily to plant chemistry, and that plant protein concentration played no detectable role. Generalist herbivores preferred non-native plants, suggesting that intact guilds of native, generalist herbivores may provide biotic resistance to plant invasions. Past invasions may have been facilitated by removal of native herbivores, introduction of

  2. Host Plant Specialization in the Sugarcane Aphid Melanaphis sacchari.

    Directory of Open Access Journals (Sweden)

    Samuel Nibouche

    Full Text Available Most aphids are highly specialized on one or two related plant species and generalist species often include sympatric populations adapted to different host plants. Our aim was to test the hypothesis of the existence of host specialized lineages of the aphid Melanaphis sacchari in Reunion Island. To this end, we investigated the genetic diversity of the aphid and its association with host plants by analyzing the effect of wild sorghum Sorghum bicolor subsp. verticilliflorum or sugarcane as host plants on the genetic structuring of populations and by performing laboratory host transfer experiments to detect trade-offs in host use. Genotyping of 31 samples with 10 microsatellite loci enabled identification of 13 multilocus genotypes (MLG. Three of these, Ms11, Ms16 and Ms15, were the most frequent ones. The genetic structure of the populations was linked to the host plants. Ms11 and Ms16 were significantly more frequently observed on sugarcane, while Ms15 was almost exclusively collected in colonies on wild sorghum. Laboratory transfer experiments demonstrated the existence of fitness trade-offs. An Ms11 isofemale lineage performed better on sugarcane than on sorghum, whereas an Ms15 lineage developed very poorly on sugarcane, and two Ms16 lineages showed no significant difference in performances between both hosts. Both field and laboratory results support the existence of host plant specialization in M. sacchari in Reunion Island, despite low genetic differentiation. This study illustrates the ability of asexual aphid lineages to rapidly undergo adaptive changes including shifting from one host plant to another.

  3. Theoretical and experimental studies on behavioral syndromes in aphids

    OpenAIRE

    Simon, Franz Wesley

    2014-01-01

    Individuals’ behaviors can be correlated across time and contexts, in a phenomenon now known as behavioral syndromes. Using an experimental approach, I demonstrate that genetically identical pea aphids are highly repeatable in multiple behavioral traits, however these behaviors are uncorrelated. Then using a state variable model I show that asymmetries in size can maintain a hierarchy between least and most bold individuals in foraging intensity across development. However, individuals tha...

  4. Orange oil effect in the control of fennel aphid

    Directory of Open Access Journals (Sweden)

    Ivanildo Cavalcanti de Albuquerque

    2009-08-01

    Full Text Available In the properties where fennel is grown, in the states of Bahia, Sergipe, Pernambuco and Paraiba, at the Northeast of Brazil, a high rate of usage of pesticides in the crop, aiming to control the aphid Hyadaphis foeniculi. The purpose of this study was to evaluate the effect of orange oil Prev-Am (sodium tetraborohydrate decahydrate, in the control of H. foeniculi aphid of the fennel crop. The trial was conducted in a fennel field located in Lagoa Seca Experimental Station, belonging to the EMEPA-PB. Forty-eight hours after the product has been sprayed, one flower of the umbel was collected and removed her aphids, which were placed in a "petri" plate from 9cm in diameter. As a following step, the insects were counted as part of two groups, considering the number of insects dead and alive, being tabulated for later analysis. The data were subjected to analysis of variance, using the experimental design of randomized blocks composed of six treatments (doses of 0.3, 0.4, 0.5, 0.6, 0.7% of orange oil (Prev-am and pure water as check, with five repetitions. The data were submitted to the regression analysis. The orange oil (Prev-am controls effectively H. foeniculi at the concentration of 0.3%, increasing the control up to concentrations of 0.6 and 0.7%. The product does not kill ladybugs (Cycloneda sanguinea and can be used in programs for integrated pest management.Keywords: Foeniculum vulgare, aphid, vegetable oil, ladybug, umbel.

  5. The Process of Aphid Egg-Laying and the Little Known Role of the Coccinellidae in Aphid Egg Destruction in Poland – Preliminary Results

    Directory of Open Access Journals (Sweden)

    Lubiarz Magdalena

    2014-07-01

    Full Text Available No detailed studies have been conducted in Poland with regard to aphid eggs or egg survival in particular. So far, no studies have been conducted concerning the role of ladybird beetles in reducing the number of aphid eggs in spring, before the development of leaves, and in autumn, after the leaves have been shed. At these times, other developmental stages of aphids are unavailable as food for the ladybirds. The paper presents the preliminary results of a three-year study on the process of aphid egg-laying (especially Chaetosiphon tetrarhodum, Macrosiphum rosae, Metopolophium dirhodum, and Maculolachnus submacula. The paper also deals with the little known role of ladybirds in aphid egg destruction. Research was conducted in Otrębusy (Western Mazovia, Poland, in the years 2008-2010, on the rugosa rose and on the dog rose. In the years 2011-2013, in Otrębusy, the occurrence of M. submacula was also observed on the ornamental grandiflora rose. Furthermore, in the years 2003-2004, observations were conducted on the pedunculate oak in Polesie National Park and in the town of Puławy (Lublin Region, Poland. The observations which took place in Puławy focused on egglaying of aphids representing the genera Phylloxera and Lachnus. The study investigated aphid oviposition sites. Data was collected on the number of aphid eggs noted on the studied plants. The study also showed, that sometimes winter eggs of aphids could provide nutrition for ladybirds. This was especially true in autumn when ladybird beetles were preparing for hibernation.

  6. Detecting changes in insect herbivore communities along a pollution gradient

    International Nuclear Information System (INIS)

    The forests surrounding the urban areas of the Los Angeles basin are impacted by ozone and nitrogen pollutants arising from urban areas. We examined changes in the herbivore communities of three prominent plant species (ponderosa pine, California black oak and bracken fern) at six sites along an air pollution gradient. Insects were extracted from foliage samples collected in spring, as foliage reached full expansion. Community differences were evaluated using total herbivore abundance, richness, Shannon-Weiner diversity, and discriminant function analysis. Even without conspicuous changes in total numbers, diversity or richness of herbivores, herbivore groups showed patterns of change that followed the air pollution gradient that were apparent through discriminant function analysis. For bracken fern and oak, chewing insects were more dominant at high pollution sites. Oak herbivore communities showed the strongest effect. These changes in herbivore communities may affect nutrient cycling in forest systems. - Differences in insect herbivore communities were associated with an ambient air pollution gradient in the mixed conifer forest outside the Los Angeles area

  7. 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

    ... the Biological Control of the Soybean Aphid in the Continental United States; Availability of an... release of Aphelinus glycinis for the biological control of the soybean aphid, Aphis glycines, in the...-2323. SUPPLEMENTARY INFORMATION: Background The soybean aphid, Aphis glycinis, which is native to...

  8. Impact of aphid alarm pheromone release on virus transmission efficiency: When pest control strategy could induce higher virus dispersion.

    Science.gov (United States)

    Lin, Fang-Jing; Bosquée, Emilie; Liu, Ying-Jie; Chen, Ju-Lian; Yong, Liu; Francis, Frédéric

    2016-09-01

    Aphids cause serious damages to crops not only by tacking sap but also by transmitting numerous viruses. To develop biological control, the aphid alarm pheromone, namely E-β-farnesene (EβF), has been demonstrated to be efficient to repel aphids and as attract beneficials, making it a potential tool to control aphid pests. Considering aphids also as virus vectors, changes of their behavior could also interfere with the virus acquisition and transmission process. Here, a combination of two aphid species and two potato virus models were selected to test the influence of EβF release on aphid and virus dispersion under laboratory conditions. EβF release was found to significantly decrease the population of Myzus persicae and Macrosiphum euphorbiae around the infochemical releaser but simultaneously also increasing the dispersal of Potato Virus Y (PVY). At the opposite, no significant difference for Potato Leaf Roll Virus (PLRV) transmission efficiency was observed with similar aphid alarm pheromone releases for none of the aphid species. These results provide some support to carefully consider infochemical releasers not only for push-pull strategy and pest control but also to include viral disease in a the plant protection to aphids as they are also efficient virus vectors. Impact of aphid kinds and transmission mechanisms will be discussed according to the large variation found between persistent and non persistent potato viruses and interactions with aphids and related infochemicals.

  9. The Process of Aphid Egg-Laying and the Little Known Role of the Coccinellidae in Aphid Egg Destruction in Poland – Preliminary Results

    OpenAIRE

    Lubiarz Magdalena; Cichocka Elżbieta

    2014-01-01

    No detailed studies have been conducted in Poland with regard to aphid eggs or egg survival in particular. So far, no studies have been conducted concerning the role of ladybird beetles in reducing the number of aphid eggs in spring, before the development of leaves, and in autumn, after the leaves have been shed. At these times, other developmental stages of aphids are unavailable as food for the ladybirds. The paper presents the preliminary results of a three-year study on the process of ap...

  10. Impact of herbivores on nitrogen cycling : contrasting effects of small and large species

    NARCIS (Netherlands)

    Bakker, ES; Olff, H; Boekhoff, M; Gleichman, JM; Berendse, F

    2004-01-01

    Herbivores are reported to slow down as well as enhance nutrient cycling in grasslands. These conflicting results may be explained by differences in herbivore type. In this study we focus on herbivore body size as a factor that causes differences in herbivore effects on N cycling. We used an exclosu

  11. Impact of herbivores on nitrogen cycling: contrasting effects of small and large species

    NARCIS (Netherlands)

    Bakker, E.S.; Olff, H.; Boekhoff, M.; Gleichman, J.M.; Berendse, F.

    2004-01-01

    Herbivores are reported to slow down as well as enhance nutrient cycling in grasslands. These conflicting results may be explained by differences in herbivore type. In this study we focus on herbivore body size as a factor that causes differences in herbivore effects on N cycling. We used an exclosu

  12. Similar and different grey matter deficits in schizophrenia patients and their unaffected biological relatives

    Directory of Open Access Journals (Sweden)

    Yuan eXiao

    2013-11-01

    Full Text Available Neuroimaging studies have revealed significant reductions in the grey matter of several brain regions in patients with schizophrenia, a neuropsychiatric disorder with high hereditability. However, it is unclear whether unaffected relatives have grey matter abnormalities in common with their affected relatives, which may relate to susceptibility to developing schizophrenia. To address this issue, we conducted two separate meta-analyses of voxel-based morphometry to investigate grey matter abnormalities in schizophrenia patients and their unaffected relatives. One meta-analysis compared a patient group with healthy controls, whereas the other meta-analysis compared the unaffected relatives with healthy controls. Eight studies comprising 495 patients with schizophrenia, 584 unaffected relatives of patients and 596 healthy controls were systematically included in the present study. Compared to healthy controls, the patient group showed decreased grey matter in the right cuneus, the right superior frontal gyrus, the right insula and the left claustrum and increased grey matter in the bilateral putamen, the right parahippocampal gyrus, the left precentral gyrus, the left inferior temporal gyri and the right cerebellar tonsil. The comparison between unaffected relatives and healthy controls showed a grey matter reduction in the left claustrum, the bilateral parahippocampal gyri, the left fusiform gyrus, the right inferior temporal gyrus, and the bilateral medial prefrontal cortices, whereas increased grey matter was observed in the right hippocampus, the right fusiform gyrus, the right precentral gyrus and the right precuneus. Thus, our meta-analyses show that the grey matter changes in schizophrenia patients and their unaffected relatives are largely different, although there is subtle overlap in some regions.

  13. Striatal morphology correlates with sensory abnormalities in unaffected relatives of cervical dystonia patients.

    LENUS (Irish Health Repository)

    Walsh, Richard A

    2012-02-01

    Structural grey matter abnormalities have been described in adult-onset primary torsion dystonia (AOPTD). Altered spatial discrimination thresholds are found in familial and sporadic AOPTD and in some unaffected relatives who may be non-manifesting gene carriers. Our hypothesis was that a subset of unaffected relatives with abnormal spatial acuity would have associated structural abnormalities. Twenty-eight unaffected relatives of patients with familial cervical dystonia, 24 relatives of patients with sporadic cervical dystonia and 27 control subjects were recruited. Spatial discrimination thresholds (SDTs) were determined using a grating orientation task. High-resolution magnetic resonance imaging (MRI) images (1.5 T) were analysed using voxel-based morphometry. Unaffected familial relatives with abnormal SDTs had reduced caudate grey matter volume (GMV) bilaterally relative to those with normal SDTs (right Z = 3.45, left Z = 3.81), where there was a negative correlation between SDTs and GMV (r = -0.76, r(2) = 0.58, p < 0.0001). Familial relatives also had bilateral sensory cortical expansion relative to unrelated controls (right Z = 4.02, left Z = 3.79). Unaffected relatives of patients with sporadic cervical dystonia who had abnormal SDTs had reduced putaminal GMV bilaterally compared with those with normal SDTs (right Z = 3.96, left Z = 3.45). Sensory abnormalities in some unaffected relatives correlate with a striatal substrate and may be a marker of genetic susceptibility in these individuals. Further investigation of grey matter changes as a candidate endophenotype may assist future genetic studies of dystonia.

  14. Responsiveness of arthropod herbivores and their natural enemies to modified weed management in corn.

    Science.gov (United States)

    Albajes, Ramon; Lumbierres, Belén; Pons, Xavier

    2009-06-01

    Alteration of weed flora as consequence of the deployment of genetically modified herbicide-tolerant crops may affect higher trophic levels in agrosystems. A 4-yr study is being conducted in Spain to investigate interrelations between weeds and associated arthropods in corn fields. In a first step, the work aimed to detect the most responsive arthropods to weed management changes. To identify the most responsive arthropods, arthropod composition and abundance in herbicide-tolerant corn plots treated twice with glyphosate and untreated plots were compared for 2 yr. Plots were sampled seven times during the season by visual inspection and pitfall and yellow sticky traps to estimate abundance and activity of the main arthropod herbivores, predators, and parasitoids. As intended, the abundance and composition of weed flora was strongly altered by the differential herbicide treatments. Several groups of arthropods responded to the weed changes but in variable directions. Whereas leafhoppers and aphids were more abundant on herbicide-treated plots, the contrary was found for phytophagous thrips. Among predators, Orius sp., spiders, and trombidids were more abundant on treated plots, whereas nabids and carabids were more abundant in untreated plots; the same case was found for carabids and spiders caught in pitfall traps. Among parasitoids, ichneumonids were more abundant in untreated plots and mymarids in treated plots. These results cannot be interpreted in terms of nontarget effects of postemergence treatments with broad-spectrum herbicides; for this, a comparison with conventional weed management practices should be done and this is the current step in the study. PMID:19508806

  15. A Novel Study on Natural Robotic Rehabilitation Exergames Using the Unaffected Arm of Stroke Patients

    OpenAIRE

    2015-01-01

    We design and implement a low-cost rehabilitation glove to meet the needs of those patients who have paralysis in their affected hand. The novelty of this glove is that it is to be worn on the unaffected hand which acts as a natural robotic arm during the rehabilitation session. The glove is equipped with FSR sensors that measure the forces exerted by the affected hand on the unaffected hand. A virtual reality rehabilitation game is developed using Microsoft Kinect to facilitate the exercises...

  16. 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 the haemo

  17. 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

  18. 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.

  19. GroEL from the endosymbiont Buchnera aphidicola betrays the aphid by triggering plant defense.

    Science.gov (United States)

    Chaudhary, Ritu; Atamian, Hagop S; Shen, Zhouxin; Briggs, Steven P; Kaloshian, Isgouhi

    2014-06-17

    Aphids are sap-feeding plant pests and harbor the endosymbiont Buchnera aphidicola, which is essential for their fecundity and survival. During plant penetration and feeding, aphids secrete saliva that contains proteins predicted to alter plant defenses and metabolism. Plants recognize microbe-associated molecular patterns and induce pattern-triggered immunity (PTI). No aphid-associated molecular pattern has yet been identified. By mass spectrometry, we identified in saliva from potato aphids (Macrosiphum euphorbiae) 105 proteins, some of which originated from Buchnera, including the chaperonin GroEL. Because GroEL is a widely conserved bacterial protein with an essential function, we tested its role in PTI. Applying or infiltrating GroEL onto Arabidopsis (Arabidopsis thaliana) leaves induced oxidative burst and expression of PTI early marker genes. These GroEL-induced defense responses required the known coreceptor BRASSINOSTEROID INSENSITIVE 1-ASSOCIATED RECEPTOR KINASE 1. In addition, in transgenic Arabidopsis plants, inducible expression of groEL activated PTI marker gene expression. Moreover, Arabidopsis plants expressing groEL displayed reduced fecundity of the green peach aphid (Myzus persicae), indicating enhanced resistance against aphids. Furthermore, delivery of GroEL into tomato (Solanum lycopersicum) or Arabidopsis through Pseudomonas fluorescens, engineered to express the type III secretion system, also reduced potato aphid and green peach aphid fecundity, respectively. Collectively our data indicate that GroEL is a molecular pattern that triggers PTI. PMID:24927572

  20. Aphidoletes aphidimyza oviposition behaviour when multiple aphid pests are present in the greenhouse

    Science.gov (United States)

    The generalist aphid predator Aphidoletes aphidimyza was investigated for oviposition behaviour on the pest aphids Myzus persicae and Aulacorthum solani in greenhouse trials. Oviposition was significantly lower on A. solani than M. persicae. Myzus persicae were concentrated at the growing points of ...

  1. 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...

  2. 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...

  3. 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...

  4. Parasitoids and hyperparasitoids (Hymenoptera) on aphids (Hemiptera) infesting citrus in east Mediterranean region of Turkey.

    Science.gov (United States)

    Satar, Serdar; Satar, Gül; Karacaoğlu, Mehmet; Uygun, Nedim; Kavallieratos, Nickolas G; Starý, Petr; Athanassiou, Christos G

    2014-01-01

    The aphids, aphid parasitoids, and hyperparasitoids found in citrus orchards, the parasitoids' and hyperparasitoids' seasonal abundance, and the plant-aphid-parasitoid relationships in Hatay, Osmaniye, Adana, and Mersin provinces of the east Mediterranean region of Turkey are presented in the present 2-yr study. Aphidius colemani Viereck, Binodoxys angelicae (Haliday), and Lysiphlebus confusus Tremblay and Eady (Hymenoptera: Braconidae: Aphidiinae) were encountered as the most common parasitoids among 10 identified aphidiine and aphelinid taxa on different citrus species. Hyperparasitoids belonging to the genera Alloxysta, Phaenoglyphis, Asaphes, Pachyneuron, Syrphophagus, and Dendrocerus are reported for the first time emerging from aphids feeding on citrus in Turkey. Among them, Asaphes spp., Pachyneuron spp., and Syrphophagus spp. were recorded as the most common ones. Citrus reticulata Blanco and Citrus limon (L.) Burm. fil. were recorded as main hosts for the aphid parasitoids and their hyperparasitoids. PMID:25480969

  5. Reliable screening technique for evaluation of wild crucifers against mustard aphid Lipaphis erysimi (Kalt.).

    Science.gov (United States)

    Singh, S P; Kumar, Sandeep; Singh, Y P; Singh, Ram

    2014-12-01

    Wild crucifers namely Arabidopsis thaliana, Brassica fruticulosa, B. rugosa, B. spinescens, B. tournefortii, Camelina sativa, Capsella bursa-pastoris, Crambe abysinnica, Cronopus didymus, Diplotaxis assurgens, D. gomez-campoi, D. muralis, D. siettiana, D. tenuisiliqua, Enatharocarpus lyratus, Lepidium sativum and Sinapis alba along with five cultivated Brassica species including B. rapa (BSH-1), B. juncea (Rohini), B. napus (GSC-6), B. carinata (DLSC-2) and Eruca sativa (T-27) were screened against mustard aphid Lipaphis erysimi (Kalt.) with a standardized technique under definite level of aphid pressure developed using specially designed cages. Observations have revealed that B. fruticulosa, B. spinescens, Camelina sativa, Crambe abysinnica and Lepidium sativum were resistant to mustard aphid L. erysimi with aphid infestation index (AII) ≤ 1. Capsella bursa-pastoris was highly susceptible to bean aphid, Aphis fabae during its vegetative stage (with 100% mortality). Other genotypes were found in the range of 'susceptible' to 'highly susceptible' with AII ranging 3-5.

  6. Herbivores and nutrients control grassland plant diversity via light limitation.

    Science.gov (United States)

    Borer, Elizabeth T; Seabloom, Eric W; Gruner, Daniel S; Harpole, W Stanley; Hillebrand, Helmut; Lind, Eric M; Adler, Peter B; Alberti, Juan; Anderson, T Michael; Bakker, Jonathan D; Biederman, Lori; Blumenthal, Dana; Brown, Cynthia S; Brudvig, Lars A; Buckley, Yvonne M; Cadotte, Marc; Chu, Chengjin; Cleland, Elsa E; Crawley, Michael J; Daleo, Pedro; Damschen, Ellen I; Davies, Kendi F; DeCrappeo, Nicole M; Du, Guozhen; Firn, Jennifer; Hautier, Yann; Heckman, Robert W; Hector, Andy; HilleRisLambers, Janneke; Iribarne, Oscar; Klein, Julia A; Knops, Johannes M H; La Pierre, Kimberly J; Leakey, Andrew D B; Li, Wei; MacDougall, Andrew S; McCulley, Rebecca L; Melbourne, Brett A; Mitchell, Charles E; Moore, Joslin L; Mortensen, Brent; O'Halloran, Lydia R; Orrock, John L; Pascual, Jesús; Prober, Suzanne M; Pyke, David A; Risch, Anita C; Schuetz, Martin; Smith, Melinda D; Stevens, Carly J; Sullivan, Lauren L; Williams, Ryan J; Wragg, Peter D; Wright, Justin P; Yang, Louie H

    2014-04-24

    Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light. PMID:24670649

  7. Herbivores and nutrients control grassland plant diversity via light limitation

    Science.gov (United States)

    Borer, Elizabeth T.; Seabloom, Eric W.; Gruner, Daniel S.; Harpole, W. Stanley; Hillebrand, Helmut; Lind, Eric M.; Alder, Peter B.; Alberti, Juan; Anderson, T. Michael; Bakker, Jonathan D.; Biederman, Lori; Blumenthal, Dana; Brown, Cynthia S.; Brudvig, Lars A.; Buckley, Yvonne M.; Cadotte, Marc; Chu, Cheng-Jin; Cleland, Elsa E.; Crawley, Michael J.; Daleo, Pedro; Damschen, Ellen Ingman; Davies, Kendi F.; DeCrappeo, Nicole M.; Du, Guozhen; Firn, Jennifer; Hautier, Yann; Heckman, Robert W.; Hector, Andy; HilleRisLambers, Janneke; Iribarne, Oscar; Klein, Julia A.; Knops, Johannes M.H.; La Pierre, Kimberly J.; Leakey, Andrew D.B.; Li, Wei; MacDougall, Andrew S.; McCulley, Rebecca L.; Melbourne, Brett A.; Mitchell, Charles E.; Moore, Joslin L.; Mortensen, Brent; O'Halloran, Lydia R.; Orrock, John L.; Pascual, Jesús; Prober, Suzanne M.; Pyke, David A.; Risch, Anita C.; Schuetz, Martin; Smith, Melinda D.; Stevens, Carly J.; Sullivan, Lauren L.; Williams, Ryan J.; Wragg, Peter D.; Wright, Justin P.; Yang, Louie H.

    2014-01-01

    Human alterations to nutrient cycles and herbivore communities are affecting global biodiversity dramatically. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.

  8. The dilemma of foraging herbivores: dealing with food and fear.

    Science.gov (United States)

    McArthur, Clare; Banks, Peter B; Boonstra, Rudy; Forbey, Jennifer Sorensen

    2014-11-01

    For foraging herbivores, both food quality and predation risk vary across the landscape. Animals should avoid low-quality food patches in favour of high-quality ones, and seek safe patches while avoiding risky ones. Herbivores often face the foraging dilemma, however, of choosing between high-quality food in risky places or low-quality food in safe places. Here, we explore how and why the interaction between food quality and predation risk affects foraging decisions of mammalian herbivores, focusing on browsers confronting plant toxins in a landscape of fear. We draw together themes of plant-herbivore and predator-prey interactions, and the roles of animal ecophysiology, behaviour and personality. The response of herbivores to the dual costs of food and fear depends on the interplay of physiology and behaviour. We discuss detoxification physiology in dealing with plant toxins, and stress physiology associated with perceived predation risk. We argue that behaviour is the interface enabling herbivores to stay or quit food patches in response to their physiological tolerance to these risks. We hypothesise that generalist and specialist herbivores perceive the relative costs of plant defence and predation risk differently and intra-specifically, individuals with different personalities and physiologies should do so too, creating individualised landscapes of food and fear. We explore the ecological significance and emergent impacts of these individual-based foraging outcomes on populations and communities, and offer predictions that can be clearly tested. In doing so, we provide an integrated platform advancing herbivore foraging theory with food quality and predation risk at its core.

  9. Hindgut Fermentation in Three Species of Marine Herbivorous Fish

    OpenAIRE

    Mountfort, Douglas O.; Campbell, Jane; Clements, Kendall D.

    2002-01-01

    Symbioses with gut microorganisms provides a means by which terrestrial herbivores are able to obtain energy. These microorganisms ferment cell wall materials of plants to short-chain fatty acids (SCFA), which are then absorbed and used by the host animal. Many marine herbivorous fishes contain SCFA (predominantly acetate) in their hindgut, indicative of gut microbial activity, but rates of SCFA production have not been measured. Such information is an important prerequisite to understanding ...

  10. Plant invasions, generalist herbivores, and novel defense weapons

    OpenAIRE

    Schaffner, Urs; Ridenour, Wendy M.; Wolf, Vera C.; Bassett, Thomas; Müller, Caroline; Müller-Schärer, Heinz; Sutherland, Steve; Lortie, Christopher J.; Callaway, Ragan M.

    2011-01-01

    One commonly accepted mechanism for biological invasions is that species, after introduction to a new region, leave behind their natural enemies and therefore increase in distribution and abundance. However, which enemies are escaped remains unclear. Escape from specialist invertebrate herbivores has been examined in detail, but despite the profound effects of generalist herbivores in natural communities their potential to control invasive species is poorly understood. We carried out parallel...

  11. 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. PMID:25290653

  12. Musculoskeletal ultrasonographic findings of the affected and unaffected shoulders in hemiplegic patients

    Directory of Open Access Journals (Sweden)

    Fatma Ali

    2016-01-01

    Conclusion Hemiplegic stroke Results in injury to the affected shoulder and the shoulder on the unaffected side. Musculoskeletal ultrasonography is an essential method in the evaluation of poststroke painful hemiplegic shoulder. However, the US grades did not correlate with the stages of motor recovery.

  13. Magnetic resonance imaging of boys with attention-deficit/hyperactivity disorder and their unaffected siblings

    NARCIS (Netherlands)

    Durston, S; Pol, HEH; Schnack, HG; Buitelaar, JK; Steenhuis, MP; Minderaa, RB; Kahn, RS; van Engeland, H

    2004-01-01

    Objective: To study the influence of increased familial risk for attention-deficit/hyperactivity disorder (ADHD) on brain morphology. Method: Volumetric cerebral measures based on whole brain magnetic resonance imaging scans from 30 boys with ADHD, 30 of their unaffected siblings, and 30 matched con

  14. Visuospatial Working Memory in ADHD Patients, Unaffected Siblings, and Healthy Controls

    NARCIS (Netherlands)

    van Ewijk, Hanneke; Heslenfeld, Dirk J.; Luman, Marjolein; Rommelse, Nanda N.; Hartman, Catharina A.; Hoekstra, Pieter; Franke, Barbara; Buitelaar, Jan K.; Oosterlaan, Jaap

    2014-01-01

    Objective: The aim of this study was to (a) test the usefulness of visuospatial working memory (VSWM) as an endophenotype for ADHD and (b) study the developmental trajectory of VSWM in ADHD. Method: A total of 110 ADHD patients, 60 unaffected siblings, and 109 controls, aged 8 to 29 years, were asse

  15. Spastic paretic stiff-legged gait: biomechanics of the unaffected limb.

    Science.gov (United States)

    Kerrigan, D C; Frates, E P; Rogan, S; Riley, P O

    1999-01-01

    A concern for individuals with hemiparesis affecting their gait, which heretofore has never been studied, is the possibility that various compensations occurring in the unaffected limb may strain or fatigue the muscles or ligaments and/or predispose to joint injury in that limb. We studied the biomechanics of the unaffected limb during walking in 20 subjects with hemiparesis who had stiff-legged gait as a result of stroke. An optoelectronic motion analysis and force platform system was used to estimate torques in all three planes about the hip, knee, and ankle. Sagittal plane joint motion and power about the unaffected hip, knee, and ankle were also studied. Data were compared with control walking data collected from 20 able-bodied controls. On average, peak torques and powers were all either reduced or the same compared with controls, even though in some instances values were >2 standard deviations (SD) above the control means. Our findings suggest that on average the probability of excessive muscular-tendon effort and the risk for biomechanical injury in the unaffected limb are minimal compared with able-bodied, walking controls. However, given individual variability, we recommend routine clinical gait analysis for all people with stiff-legged gait to eliminate excessive values in certain biomechanical parameters, which could, if not addressed, predispose to muscle-tendon strain or joint or ligamentous injury.

  16. Unaffected Arm Muscle Hypercatabolism in Dysphagic Subacute Stroke Patients: The Effects of Essential Amino Acid Supplementation

    Directory of Open Access Journals (Sweden)

    Roberto Aquilani

    2014-01-01

    Full Text Available Alterations in muscle protein turnover of the unaffected side of stroke patients could contribute to physical disability. We investigated whether hypercatabolic activity occurred in unaffected arm muscle and whether supplemented essential amino acids (EAAs could limit muscle hypercatabolism (MH. Thirty-eight dysphagic subacute stroke subjects (<3 months after acute event (29 males + 9 females; 69.7 ± 11.4 yrs were enrolled and randomized to receive 8 g/day EAAs (n = 19; EAA group or isocaloric placebo (maltodextrin; n = 19, Plac group. Before randomization, all patients had their arterial (A and venous (V amino acids measured and muscle (A − V differences calculated in the unaffected arm. Eight matched and healthy subjects served as controls. When compared to healthy controls, the entire stroke population showed significant muscle release (= negative value A − V of the amino acid phenylalanine (phenyl- indicating a prevalence of MH. Moreover, randomized EAA and Plac groups had similar rates of MH. After 38 days from the start of the protocol, the EAA group but not the Plac group had MH converted to balanced protein turnover or anabolic activity. We concluded that muscle protein metabolism of the unaffected arm of dysphagic subacute stroke individuals could be characterized by MH which can be corrected by supplemented EAAs.

  17. Unaffected Arm Muscle Hypercatabolism in Dysphagic Subacute Stroke Patients: The Effects of Essential Amino Acid Supplementation

    Science.gov (United States)

    Aquilani, Roberto; Boselli, Mirella; D'Antona, Giuseppe; Baiardi, Paola; Boschi, Federica; Viglio, Simona; Iadarola, Paolo; Pasini, Evasio; Barbieri, Annalisa; Dossena, Maurizia; Bongiorno, Andria Innocenza; Verri, Manuela

    2014-01-01

    Alterations in muscle protein turnover of the unaffected side of stroke patients could contribute to physical disability. We investigated whether hypercatabolic activity occurred in unaffected arm muscle and whether supplemented essential amino acids (EAAs) could limit muscle hypercatabolism (MH). Thirty-eight dysphagic subacute stroke subjects (<3 months after acute event) (29 males + 9 females; 69.7 ± 11.4 yrs) were enrolled and randomized to receive 8 g/day EAAs (n = 19; EAA group) or isocaloric placebo (maltodextrin; n = 19, Plac group). Before randomization, all patients had their arterial (A) and venous (V) amino acids measured and muscle (A − V) differences calculated in the unaffected arm. Eight matched and healthy subjects served as controls. When compared to healthy controls, the entire stroke population showed significant muscle release (= negative value A − V) of the amino acid phenylalanine (phenyl-) indicating a prevalence of MH. Moreover, randomized EAA and Plac groups had similar rates of MH. After 38 days from the start of the protocol, the EAA group but not the Plac group had MH converted to balanced protein turnover or anabolic activity. We concluded that muscle protein metabolism of the unaffected arm of dysphagic subacute stroke individuals could be characterized by MH which can be corrected by supplemented EAAs. PMID:25431770

  18. Neurocognitive functions in obsessive-compulsive disorder patients and their unaffected first-degree relatives

    Institute of Scientific and Technical Information of China (English)

    张龙

    2012-01-01

    Objective To find the common neurocognitive deficits in patients with obsessive-compulsive disorder (OCD) and their unaffected first-degree relatives (UFDR) and to identify neurocognitive endophenotypes for OCD. Methods Forty patients with OCD,forty UFDR of OCD probands and forty healthy

  19. Social motor coordination in unaffected relatives of schizophrenia patients: A potential intermediate phenotype

    Directory of Open Access Journals (Sweden)

    Jonathan eDel-Monte

    2013-10-01

    Full Text Available Intermediate endophenotypes emerge as an important concept in the study of schizophrenia. Although research on phenotypes mainly investigated cognitive, metabolic or neurophysiological markers so far, some authors also examined the motor behaviour anomalies as potential trait-marker of the disease. However, none of them investigated social motor coordination despite the importance of their anomalies in schizophrenia. The aim of this study was thus to determine whether coordination modifications previously demonstrated in schizophrenia are trait-markers that might be associated with the risk for this pathology. Interpersonal motor coordination in 27 unaffected first-degree relatives of schizophrenia patients and 27 healthy controls was assessed using a hand-held pendulum task to examine the presence of interpersonal coordination impairments in individuals at risk for the disorder. Measures of neurologic soft signs, clinical variables and neurocognitive functions were collected to assess the cognitive and clinical correlates of social coordination impairments in at-risk relatives. After controlling for potential confounding variables, unaffected relatives of schizophrenia patients had impaired intentional interpersonal coordination compared to healthy controls while unintentional interpersonal coordination was preserved. More specifically, in intentional coordination, the unaffected relatives of schizophrenia patients exhibited coordination patterns that had greater variability and in which relatives did not lead the coordination. These results show that unaffected relatives of schizophrenia patients also present deficits in intentional interpersonal coordination. For the first time, these results suggest that intentional interpersonal coordination impairments might be a potential motor intermediate endophenotype of schizophrenia opening new perspectives for early diagnosis.

  20. Weed Host Specificity of the Aphid, Aphis spiraecola: Developmental and Reproductive Performance of Aphids in Relation to Plant Growth and Leaf Chemicals of the Siam Weed, Chromolaena odorata

    OpenAIRE

    Agarwala, B. K.; Das, Jhuma

    2012-01-01

    Density, distribution, and nutritional quality of plants are the causal basis of host plant selection in aphids. Nutritional qualities of a plant vary according to its growth stage and also in response to seasonal variation. How host plant growth stages shape aphid performance was studied in Aphis spiraecola Patch (Homoptera: Aphididae) on the perennial Siam weed, Chromolaena odorata (L.) King and Robinson (Asterales: Asteraceae). This plant species is the preferred host in the hot and humid ...

  1. 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

    OpenAIRE

    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

    Background 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. Methods 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 ide...

  2. Functional reorganization of human motor cortex after unaffected side C7 nerve root transposition

    International Nuclear Information System (INIS)

    Objective: To assess the characteristics of neuronal activity in human motor cortex after the seventh cervical nerve root transposition of the unaffected side by using functional MRI (fMRI). Methods: Thirteen patients who accepted the seventh cervical nerve root transposition of the unaffected side, due to total brachial plexus traction injury diagnosed by manifestation and operation, were examined retrospectively by using fMRI. 10 patients were injured on the left side and 3 on the right side. According to functional recovery of the affected hand, all subjects can be divided into 2 groups. The patients of the first group could not move the affected hand voluntarily. The patients of the second group could move the affected hand self-determined. 12 healthy volunteer's were also involved in this study as control. The fMRI examinations were performed by using echo-planer BOLD sequence. Then the SPM 99 software was used for post-processing. Results: The neuronal activation induced by the movement of both unaffected and affected upper' limb was seen in the contralateral PMC in all patients; Neuronal activation in the ipsilateral PMC evoked by movement of the unaffected extremity was seen in 10 cases, and induced by movement of the affected limb was seen in 7 cases. In the first group, the sharp of clusters in the contralateral PMC resulted by movement of the unaffected extremity showed normal in 9 eases, the average size of clusters resulted by the unaffected hand was 3159 (voxel), and resulted by the unaffected shoulder was 1746(voxel). The sharp of clusters in the contralateral PMC resulted by the affected shoulder or hand were revealed enlargement in 6 cases of each. In the second group, 1 case showed neuronal activation induced by movement of the affected limb in the PMC in both sides of motor cortex, and 2 cases showed neuronal activation in the contralateral PMC. Conclusions: Peripheral nerve injury was able to cause changes of motor cortex in human brain

  3. Feeding by the aphid Sipha flava produces a reddish spot on leaves of Sorghum halepense: an induced defense?

    Science.gov (United States)

    Costa-Arbulú, C; Gianoli, E; Gonzáles, W L; Niemeyer, H M

    2001-02-01

    Feeding by the aphid Sipha flava produces a reddish spot on mature leaves of Sorghum halepense. The present work is aimed at determining whether this plant response entails induced resistance against the aphid. Old and young leaves showed the same response to aphid feeding (reddish coloration). Water-stressed plants displayed a similar reddish coloration to aphid-infested plants. This was verified by evaluation of absorbance peaks of the respective leaf extracts. Aphid fecundity was reduced on previously infested (and hence reddish colored) leaves. However, aphid fecundity was not affected on water stressed plants. Furthermore, aphid survival was not different on artificial diets containing increasing concentrations of the reddish pigment. It is concluded that the reddish spot is correlated with, but is not itself responsible for, the observed induced resistance of S. halepense against S. flava.

  4. Influence of global atmospheric change on the feeding behavior and growth performance of a mammalian herbivore, Microtus ochrogaster.

    Directory of Open Access Journals (Sweden)

    Christopher W Habeck

    Full Text Available Global atmospheric change is influencing the quality of plants as a resource for herbivores. We investigated the impacts of elevated carbon dioxide (CO2 and ozone (O3 on the phytochemistry of two forbs, Solidago canadensis and Taraxacum officinale, and the subsequent feeding behavior and growth performance of weanling prairie voles (Microtus ochrogaster feeding on those plants. Plants for the chemical analyses and feeding trials were harvested from the understory of control (ambient air, elevated CO2 (560 µl CO2 l(-1, and elevated O3 (ambient × 1.5 rings at the Aspen FACE (Free Air CO2 Enrichment site near Rhinelander, Wisconsin. We assigned individual voles to receive plants from only one FACE ring and recorded plant consumption and weanling body mass for seven days. Elevated CO2 and O3 altered the foliar chemistry of both forbs, but only female weanling voles on the O3 diet showed negative responses to these changes. Elevated CO2 increased the fiber fractions of both plant species, whereas O3 fumigation elicited strong responses among many phytochemical components, most notably increasing the carbon-to-nitrogen ratio by 40% and decreasing N by 26%. Consumption did not differ between plant species or among fumigation treatments. Male voles were unaffected by the fumigation treatments, whereas female voles grew 36% less than controls when fed O3-grown plants. These results demonstrate that global atmospheric change has the potential to affect the performance of a mammalian herbivore through changes in plant chemistry.

  5. The genomewide transcriptional response underlying the pea aphid wing polyphenism.

    Science.gov (United States)

    Vellichirammal, Neetha N; Madayiputhiya, Nandakumar; Brisson, Jennifer A

    2016-09-01

    Phenotypic plasticity is a key life history strategy used by many plants and animals living in heterogeneous environments. A multitude of studies have investigated the costs and limits of plasticity, as well as the conditions under which it evolves. Much less well understood are the molecular genetic mechanisms that enable an organism to sense its environment and respond in a plastic manner. The pea aphid wing polyphenism is a compelling laboratory model to study these mechanisms. In this polyphenism, environmental stressors like high density cause asexual, viviparous adult female aphids to change the development of their embryos from wingless to winged morphs. The life history trade-offs between the two morphs have been intensively studied, but the molecular mechanisms underlying this process remain largely unknown. We therefore performed a genomewide study of the maternal transcriptome at two time points with and without a crowding stress to discover the maternal molecular changes that lead to the development of winged vs. wingless offspring. We observed significant transcriptional changes in genes associated with odorant binding, neurotransmitter transport, hormonal activity and chromatin remodelling in the maternal transcriptome. We also found that titres of serotonin, dopamine and octopamine were higher in solitary compared to crowded aphids. We use these results to posit a model for how maternal signals inform a developing embryo to be winged or wingless. Our findings add significant insights into the identity of the molecular mechanisms that underlie environmentally induced morph determination and suggest a possible role for biogenic amine regulation in polyphenisms generally. PMID:27393739

  6. Herbivore-induced volatile emission in black poplar: regulation and role in attracting herbivore enemies.

    Science.gov (United States)

    Clavijo McCormick, Andrea; Irmisch, Sandra; Reinecke, Andreas; Boeckler, G Andreas; Veit, Daniel; Reichelt, Michael; Hansson, Bill S; Gershenzon, Jonathan; Köllner, Tobias G; Unsicker, Sybille B

    2014-08-01

    After herbivory, plants release volatile organic compounds from damaged foliage as well as from nearby undamaged leaves that attract herbivore enemies. Little is known about what controls the volatile emission differences between damaged and undamaged tissues and how these affect the orientation of herbivore enemies. We investigated volatile emission from damaged and adjacent undamaged foliage of black poplar (Populus nigra) after herbivory by gypsy moth (Lymantria dispar) caterpillars and determined the compounds mediating the attraction of the gypsy moth parasitoid Glyptapanteles liparidis (Braconidae). Female parasitoids were more attracted to gypsy moth-damaged leaves than to adjacent non-damaged leaves. The most characteristic volatiles of damaged versus neighbouring undamaged leaves included terpenes, green leaf volatiles and nitrogen-containing compounds, such as aldoximes and nitriles. Electrophysiological recordings and olfactometer bioassays demonstrated the importance of nitrogenous volatiles. Under field conditions, parasitic Hymenoptera were more attracted to traps baited with these substances than most other compounds. The differences in volatile emission profiles between damaged and undamaged foliage appear to be regulated by jasmonate signalling and the local activation of volatile biosynthesis. We conclude that characteristic volatiles from damaged black poplar foliage are essential cues enabling parasitoids to find their hosts.

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

    Directory of Open Access Journals (Sweden)

    Eduardo Hatano

    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.

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

    Directory of Open Access Journals (Sweden)

    Hubert Sytykiewicz

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

    International Nuclear Information System (INIS)

    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)

  10. Studies on the Host Biotypes and Its Cause of Cotton Aphid in Nanjing, China

    Institute of Scientific and Technical Information of China (English)

    LIU Xiang-dong; ZHAI Bao-ping; ZHANG Xiao-xi

    2002-01-01

    The fitness of cotton aphid, Aphis gossypii Glover, on different host plants was studied. The results showed that the cotton aphid population in Nanjing formed host preference bio-types on cucumber and cotton. The aphids from cotton and cucumber could not inter-transplant successfully between the two host plants. The apterous and alate offspring of stem mother from hibiscus could not survive, reproduce and form population normally when they were transplanted to cucumber and water melon, but they could form normally when transplanted to cotton and muskmelon. There was no significant difference between the stylet length of cotton aphids from cucumber and cotton, so the stylet length was not the cause of the host preference. When the aphids originated on hibiscus were transplanted to cotton, water melon and muskmelon, the stylet could reach host phloem to absorb host plant's nutrients, but it couldn't when transplanted to cucumber. Cotton aphid can feed on muskmelon without secretion of water-soluble saliva. It could be concluded that the two host biotypes of cotton aphid came from different winter host plants.

  11. Small herbivores suppress algal accumulation on Agatti atoll, Indian Ocean

    Science.gov (United States)

    Cernohorsky, Nicole H.; McClanahan, Timothy R.; Babu, Idrees; Horsák, Michal

    2015-12-01

    Despite large herbivorous fish being generally accepted as the main group responsible for preventing algal accumulation on coral reefs, few studies have experimentally examined the relative importance of herbivore size on algal communities. This study used exclusion cages with two different mesh sizes (1 × 1 cm and 6 × 6 cm) to investigate the impact of different-sized herbivores on algal accumulation rates on the shallow (herbivores, which had rapid and lasting effects on the benthic communities, and, after 127 d of deployment, there was a visible and significant increase in algae (mainly macroalgae) with algal volume being 13 times greater than in adjacent open areas. The coarse-mesh cages excluded larger fishes (>8 cm body depth) while allowing smaller fishes to access the plots. In contrast to the conclusions of most previous studies, the exclusion of large herbivores had no significant effect on the accumulation of benthic algae and the amount of algae present within the coarse-mesh cages was relatively consistent throughout the experimental period (around 50 % coverage and 1-2 mm height). The difference in algal accumulation between the fine-mesh and coarse-mesh cages appears to be related to the actions of small individuals from 12 herbivorous fish species (0.17 ind. m-2 and 7.7 g m-2) that were able to enter through the coarse mesh. Although restricted to a single habitat, these results suggest that when present in sufficient densities and diversity, small herbivorous fishes can prevent the accumulation of algal biomass on coral reefs.

  12. Evaluating herbivore management outcomes and associated vegetation impacts

    Directory of Open Access Journals (Sweden)

    Rina C.C. Grant

    2011-05-01

    Full Text Available African savannas are characterised by temporal and spatial fluxes that are linked to fluxes in herbivore populations and vegetation structure and composition. We need to be concerned about these fluxes only when management actions cause the system to shift towards a less desired state. Large herbivores are a key attribute of African savannas and are important for tourism and biodiversity. Large protected areas such as the Kruger National Park (KNP manage for high biodiversity as the desired state, whilst private protected areas, such as those adjacent to the KNP, generally manage for high income. Biodiversity, sustainability and economic indicators are thus required to flag thresholds of potential concern (TPCs that may result in a particular set of objectives not being achieved. In large conservation areas such as the KNP, vegetation changes that result from herbivore impact, or lack thereof, affect biodiversity and TPCs are used to indicate unacceptable change leading to a possible loss of biodiversity; in private protected areas the loss of large herbivores is seen as an important indicator of economic loss. Therefore, the first-level indicators aim to evaluate the forage available to sustain grazers without deleteriously affecting the vegetation composition, structure and basal cover. Various approaches to monitoring for these indicators were considered and the importance of the selection of sites that are representative of the intensity of herbivore use is emphasised. The most crucial step in the adaptive management process is the feedback of information to inform management decisions and enable learning. Feedback loops tend to be more efficient where the organisation’s vision is focused on, for example, economic gain, than in larger protected areas, such as the KNP, where the vision to conserve biodiversity is broader and more complex.Conservation implications: In rangeland, optimising herbivore numbers to achieve the management

  13. 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. PMID:26313961

  14. Musculoskeletal ultrasonographic findings of the affected and unaffected shoulders in hemiplegic patients

    OpenAIRE

    Fatma Ali; Mona Hamdy; Rasha A Abdel-Magied; Mostafa M Elian

    2016-01-01

    Background There are many sonographic changes in affected and unaffected shoulders in patients with established hemiplegia. Aim The aim of this study was to evaluate the sonographic findings of hemiplegic shoulder in patients after acute stroke and the detection of the correlation between the physical or sonographic findings and early-onset hemiplegic shoulder pain. Patients and methods Shoulders of 30 patients with cerebrovascular stroke (six male and 24 female patients), 18...

  15. Changes in activity of lysine decarboxylase in winter triticale in response to grain aphid feeding.

    Science.gov (United States)

    Sempruch, C; Leszczyński, B; Wójcicka, Agnieszka; Makosz, M; Matok, H; Chrzanowski, G

    2010-12-01

    Changes in lysine decarboxylase (LDC) activity caused by Sitobion avenae (F.) feeding on two winter triticale cultivars (cvs) were studied. The aphid fecundity and values of intrinsic rate of natural increase showed that cv Witon was less susceptible to S. avenae than cv Tornado. The grain aphid feeding on more susceptible triticale caused a decrease in the LDC activity, with exceptions of root tissues after two weeks of the feeding. In case of less susceptible cv Witon reduction of the LDC activity was observed only during initial period of S. avenae feeding. Later the aphid infestation induced activity of the LDC within tissues of cv Witon. PMID:21112841

  16. Familial idiopathic pulmonary fibrosis. Evidence of lung inflammation in unaffected family members

    International Nuclear Information System (INIS)

    We evaluated 17 clinically unaffected members of three families with an autosomal dominant form of idiopathic pulmonary fibrosis for evidence of alveolar inflammation. Each person in the study was examined by gallium-67 scanning for a general estimate of pulmonary inflammation, and by bronchoalveolar lavage for characterization of the types of recovered cells and their state of activation. Eight of the 17 subjects had evidence of alveolar inflammation on the lavage studies. Supporting data included increased numbers of neutrophils and activated macrophages that released one or more neutrophil chemoattractants, and growth factors for lung fibroblasts--findings similar to those observed in patients with overt idiopathic pulmonary fibrosis. Four of these eight also had a positive gallium scan; in all the other clinically unaffected subjects the scan was normal. During a follow-up of two to four years in seven of the eight subjects who had evidence of inflammation, no clinical evidence of pulmonary fibrosis has appeared. These results indicate that alveolar inflammation occurs in approximately half the clinically unaffected family members at risk of inheriting autosomal dominant idiopathic pulmonary fibrosis. Whether these persons with evidence of pulmonary inflammation but no fibrosis will proceed to have clinically evident pulmonary fibrosis is not yet known

  17. Parasitism overrides herbivore identity allowing hyperparasitoids to locate their parasitoid host using herbivore-induced plant volatiles.

    Science.gov (United States)

    Zhu, Feng; Broekgaarden, Colette; Weldegergis, Berhane T; Harvey, Jeffrey A; Vosman, Ben; Dicke, Marcel; Poelman, Erik H

    2015-06-01

    Foraging success of predators profoundly depends on reliable and detectable cues indicating the presence of their often inconspicuous prey. Carnivorous insects rely on chemical cues to optimize foraging efficiency. Hyperparasitoids that lay their eggs in the larvae or pupae of parasitic wasps may find their parasitoid hosts developing in different herbivores. They can use herbivore-induced plant volatiles (HIPVs) to locate parasitized caterpillars. Because different herbivore species induce different HIPV emission from plants, hyperparasitoids may have to deal with large variation in volatile information that indicates host presence. In this study, we used an ecogenomics approach to first address whether parasitized caterpillars of two herbivore species (Pieris rapae and P. brassicae) induce similar transcriptional and metabolomic responses in wild Brassica oleracea plants and, second, whether hyperparasitoids Lysibia nana are able to discriminate between these induced plant responses to locate their parasitoid host in different herbivores under both laboratory and field conditions. Our study revealed that both herbivore identity and parasitism affect plant transcriptional and metabolic responses to herbivory. We also found that hyperparasitoids are able to respond to HIPVs released by wild B. oleracea under both laboratory and field conditions. In addition, we observed stronger attraction of hyperparasitoids to HIPVs when plants were infested with parasitized caterpillars. However, hyperparasitoids were equally attracted to plants infested by either herbivore species. Our results indicate that parasitism plays a major role in HIPV-mediated plant-hyperparasitoid interactions. Furthermore, these findings also indicate that plant trait-mediated indirect interaction networks play important roles in community-wide species interactions. PMID:25789566

  18. Host settling behavior, reproductive performance, and effects on plant growth of an exotic cereal aphid, Metopolophium festucae subsp. cerealium (Hemiptera: Aphididae).

    Science.gov (United States)

    Davis, T S; Wu, Y; Eigenbrode, S D

    2014-06-01

    The cereal aphid Metopolophium festucae subsp. cerealium (Stroyan) is a recent addition to North America, but little is known about this species in its exotic habitat. We surveyed aphid populations for 3 years (2011-2013) to investigate changes in aphid density in the Pacific Northwest United States. We tested aphid host settling preference and fecundity on eight grass species, four native grasses (bluebunch wheatgrass, blue wild rye, Idaho fescue, and rough fescue) and four cereal crops (corn, wheat, barley, and oat), and evaluated the effects of aphid feeding on plant biomass. Four important findings emerged: 1) aphid prevalence in sweep net samples increased from 2011 to 2012, but remained stable from 2012 to 2013; 2) aphids preferentially settled on wheat and avoided corn, but aphids did not discriminate between barley, oat, and native grasses; 3) aphid fecundity was high on wheat and barley, intermediate on oat and blue wild rye, low on Idaho fescue, rough fescue, and bluebunch wheatgrass, and aphids did not reproduce at all on corn; and 4) barley, corn, oats, Idaho fescue, and blue wild rye were not susceptible to aphid feeding damage, but wheat, rough fescue, and bluebunch wheatgrass were susceptible to aphid feeding damage. Our results suggest that wheat and barley are preferred by M. festucae cerealium, and that aphids reproduce most rapidly on these hosts and cause significant reductions in wheat but not barley growth. Also, M. festucae cerealium appears capable of surviving on native grasses, although only bluebunch wheatgrass and rough fescue were susceptible to aphid feeding damage.

  19. Powdery mildew suppresses herbivore-induced plant volatiles and interferes with parasitoid attraction in Brassica rapa.

    Science.gov (United States)

    Desurmont, Gaylord A; Xu, Hao; Turlings, Ted C J

    2016-09-01

    The co-occurrence of different antagonists on a plant can greatly affect infochemicals with ecological consequences for higher trophic levels. Here we investigated how the presence of a plant pathogen, the powdery mildew Erysiphe cruciferarum, on Brassica rapa affects (1) plant volatiles emitted in response to damage by a specialist herbivore, Pieris brassicae; (2) the attraction of the parasitic wasp Cotesia glomerata and (3) the performance of P. brassicae and C. glomerata. Plant volatiles were significantly induced by herbivory in both healthy and mildew-infected plants, but were quantitatively 41% lower for mildew-infected plants compared to healthy plants. Parasitoids strongly preferred Pieris-infested plants to dually-infested (Pieris + mildew) plants, and preferred dually infested plants over only mildew-infected plants. The performance of P. brassicae was unaffected by powdery mildew, but C. glomerata cocoon mass was reduced when parasitized caterpillars developed on mildew-infected plants. Thus, avoidance of mildew-infested plants may be adaptive for C. glomerata parasitoids, whereas P. brassicae caterpillars may suffer less parasitism on mildew-infected plants in nature. From a pest management standpoint, the concurrent presence of multiple plant antagonists can affect the efficiency of specific natural enemies, which may in turn have a negative impact on the regulation of pest populations. PMID:27043839

  20. [UV-induced DNA mutation of peach aphid].

    Science.gov (United States)

    Du, Erxia; Guo, Jianwen; Zhao, Huiyan

    2006-07-01

    By using PCR technique and microsatellite marks, this paper studied the DNA polymorphism of peach aphid (Myzus persicae) under UV-radiation. The fragments of three primers were amplified, and the gene diversity and the rate of loci polymorphisms of their genomic DNA, which could reflect the damage degree of DNA after UV-radiation, were measured. The results revealed that after treated with different radiation intensity (15, 30, 45 W) and duration (2, 4, 6 h) , the UV-induced DNA mutations were genetic and could be delivered to F2 generation. The mutations depended on the interaction of radiation intensity and duration. Variance analysis on the gene diversity and the rate of loci polymorphisms showed that there existed a significant difference between UV-treated and control groups, except the rate of loci polymorphisms under 2 h radiation. The average value of the control was higher than that of 2 h radiation treatment. According to the cluster analysis of the genetic distance, the aphids were divided into three groups, i. e., control group, 2 h (15, 30 W) treatment group, and the other, which was consistent with the result of variance analysis.

  1. Preference for outbred host plants and positive effects of inbreeding on egg survival in a specialist herbivore

    OpenAIRE

    Kalske, Aino; Muola, Anne; Mutikainen, Pia; Leimu, Roosa

    2014-01-01

    Inbreeding can profoundly affect the interactions of plants with herbivores as well as with the natural enemies of the herbivores. We studied how plant inbreeding affects herbivore oviposition preference, and whether inbreeding of both plants and herbivores alters the probability of predation or parasitism of herbivore eggs. In a laboratory preference test with the specialist herbivore moth Abrostola asclepiadis and inbred and outbred Vincetoxicum hirundinaria plants, we discovered that herbi...

  2. Gut microbes of mammalian herbivores facilitate intake of plant toxins.

    Science.gov (United States)

    Kohl, Kevin D; Weiss, Robert B; Cox, James; Dale, Colin; Dearing, M Denise

    2014-10-01

    The foraging ecology of mammalian herbivores is strongly shaped by plant secondary compounds (PSCs) that defend plants against herbivory. Conventional wisdom holds that gut microbes facilitate the ingestion of toxic plants; however, this notion lacks empirical evidence. We investigated the gut microbiota of desert woodrats (Neotoma lepida), some populations of which specialise on highly toxic creosote bush (Larrea tridentata). Here, we demonstrate that gut microbes are crucial in allowing herbivores to consume toxic plants. Creosote toxins altered the population structure of the gut microbiome to facilitate an increase in abundance of genes that metabolise toxic compounds. In addition, woodrats were unable to consume creosote toxins after the microbiota was disrupted with antibiotics. Last, ingestion of toxins by naïve hosts was increased through microbial transplants from experienced donors. These results demonstrate that microbes can enhance the ability of hosts to consume PSCs and therefore expand the dietary niche breadth of mammalian herbivores.

  3. Multi-factor climate change effects on insect herbivore performance

    DEFF Research Database (Denmark)

    Scherber, Christoph; Gladbach, David J; Stevnbak, Karen;

    2013-01-01

    The impact of climate change on herbivorous insects can have far-reaching consequences for ecosystem processes. However, experiments investigating the combined effects of multiple climate change drivers on herbivorous insects are scarce. We independently manipulated three climate change drivers (CO...... the drought treatment, and there was a three-way interaction between time, CO2, and drought. Survival was lowest when drought, warming, and elevated CO2 were combined. Effects of climate change drivers depended on other co-acting factors and were mediated by changes in plant secondary compounds, nitrogen...... suturalis Thomson), an important herbivore on heather, to ambient versus elevated drought, temperature, and CO2 (plus all combinations) for 5 weeks. Larval weight and survival were highest under ambient conditions and decreased significantly with the number of climate change drivers. Weight was lowest under...

  4. Arabidopsis thaliana Responses to Aphid Infestation

    OpenAIRE

    Kusnierczyk, Anna

    2008-01-01

    Interactions between plants and herbivorous insects, as they are shaped today, result from a long process of evolutionary adaptation. A whole arsenal of defence mechanisms has been developed to protect plants from a variety of enemies. Some of them are general and provide protection from a wide range of insects, whereas others are more specific against particular types of attackers. Plants are equipped with systems for perception of attack which trigger activation of signalling pathways and i...

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

    Science.gov (United States)

    Song, Nan; Zhang, Hao; Li, Hu; Cai, Wanzhi

    2016-01-01

    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. PMID:27314587

  6. 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.

  7. Distance and sex determine host plant choice by herbivorous beetles.

    Directory of Open Access Journals (Sweden)

    Daniel J Ballhorn

    Full Text Available BACKGROUND: Plants respond to herbivore damage with the release of volatile organic compounds (VOCs. This indirect defense can cause ecological costs when herbivores themselves use VOCs as cues to localize suitable host plants. Can VOCs reliably indicate food plant quality to herbivores? METHODOLOGY: We determined the choice behavior of herbivorous beetles (Chrysomelidae: Gynandrobrotica guerreroensis and Cerotoma ruficornis when facing lima bean plants (Fabaceae: Phaseolus lunatus with different cyanogenic potential, which is an important constitutive direct defense. Expression of inducible indirect defenses was experimentally manipulated by jasmonic acid treatment at different concentrations. The long-distance responses of male and female beetles to the resulting induced plant volatiles were investigated in olfactometer and free-flight experiments and compared to the short-distance decisions of the same beetles in feeding trials. CONCLUSION: Female beetles of both species were repelled by VOCs released from all induced plants independent of the level of induction. In contrast, male beetles were repelled by strongly induced plants, showed no significant differences in choice behavior towards moderately induced plants, but responded positively to VOCs released from little induced plants. Thus, beetle sex and plant VOCs had a significant effect on host searching behavior. By contrast, feeding behavior of both sexes was strongly determined by the cyanogenic potential of leaves, although females again responded more sensitively than males. Apparently, VOCs mainly provide information to these beetles that are not directly related to food quality. Being induced by herbivory and involved in indirect plant defense, such VOCs might indicate the presence of competitors and predators to herbivores. We conclude that plant quality as a food source and finding a potentially enemy-free space is more important for female than for male insect herbivores

  8. Characterisation and cross-amplification of polymorphic microsatellite loci in ant-associated root-aphids

    DEFF Research Database (Denmark)

    Ivens, A.B.F.; Kronauer, Daniel Jan Christoph; Boomsma, J.J.

    2011-01-01

    Twenty-six polymorphic microsatellite loci were developed for four species of ant-associated root-aphids: Geoica utricularia, Forda marginata, Tetraneura ulmi and Anoecia corni. We found up to 9 alleles per locus, with an average of 4.8. We also report polymorphic cross-amplification of eleven...... of these markers between different pairs of study species. Furthermore, we tested previously published aphid microsatellites and found one locus developed for Pemphigus bursarius to be polymorphic in G. utricularia. These microsatellite markers will be useful to study the population structure of aphids associated...... with the ant Lasius flavus and possibly other ants. Such studies are relevant because: 1. L. flavus mounds and their associated flora and fauna are often key components in protected temperate grasslands, and 2. L. flavus and its diverse community of root-aphids provide an interesting model system for studying...

  9. Natural enemies of woolly apple aphid (Hemiptera: Aphididae) in Washington State.

    Science.gov (United States)

    Gontijo, Lessando M; Cockfield, Stephen D; Beers, Elizabeth H

    2012-12-01

    Woolly apple aphid, Eriosoma lanigerum (Hausmann), has become a pest of increasing importance in Washington apple orchards in the past decade. The increase in aphid outbreaks appears to be associated with changes in pesticide programs and disruption of biological control. We sampled woolly apple aphid colonies in central Washington apple orchards for natural enemies of this pest from 2006 to 2008. The most common predators encountered were Syrphidae (Syrphus opinator Osten Sacken, Eupeodes fumipennis Thomson, and Eupeodes americanus Wiedemann); Chrysopidae (Chrysopa nigricornis Burmeister); and Coccinellidae (Coccinella transversoguttata Brown and Hippodamia convergens Guérin-Méneville). The specialist syrphid Heringia calcarata Loew was recorded for the first time occurring in Washington apple orchards. The only parasitoid found in aerial colonies of woolly apple aphid was Aphelinus mali Haldeman; root colonies, however, were not parasitized. Identification of important natural enemies provides a better basis for conservation biological control of this pest.

  10. 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

    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...... 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....... ulmi) occurred within a few km of the study population. We discuss the extent to which obligate ant-tending and absence of primary hosts may have affected selection for permanent parthenogenesis, and we highlight the need for further study of these aphids in Southern Europe where primary hosts may occur close...

  11. Kaolin particle films suppress many apple pests, disrupt natural enemies and promote woolly apple aphid

    NARCIS (Netherlands)

    Markó, V.; Blommers, L.H.M.; Bogya, S.; Helsen, H.H.M.

    2008-01-01

    Multiple applications of hydrophobic kaolin particle film in apple orchards suppressed numbers of blossom weevil (Anthonomus pomorum), brown leaf weevil (Phyllobius oblongus), attelabid weevil (Caenorhinus pauxillus), leafhoppers (Empoasca vitis and Zygina flammigera) and green apple aphid (Aphis po

  12. Herbivore effects on productivity vary by guild: cattle increase mean productivity while wildlife reduce variability

    Science.gov (United States)

    Ungulate wild herbivores and livestock share the majority of rangelands worldwide; yet few controlled experiments have addressed their individual, additive, and interactive impacts on ecosystem function and productivity. While ungulate herbivores generally reduce standing biomass, their effects on a...

  13. Herbaceous forage and selection patterns by ungulates across varying herbivore assemblages in a South African savanna

    NARCIS (Netherlands)

    Treydte, A.C.; Baumgartner, S.; Heitkonig, I.M.A.; Grant, C.C.; Getz, W.M.

    2013-01-01

    Herbivores generally have strong structural and compositional effects on vegetation, which in turn determines the plant forage species available. We investigated how selected large mammalian herbivore assemblages use and alter herbaceous vegetation structure and composition in a southern African sav

  14. Fish, Benthic and Urchin Survey Data from Kahekili Herbivore Fisheries Management Area (HFMA), Maui since 2008

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2009, the state of Hawaii established the Kahekili Herbivore Fisheries Management Area (KHFMA) in West Maui. Fishing for herbivores (parrotfishes, surgeonfishes,...

  15. Vegetation factors influencing density and distribution of wild large herbivores in a southern African savannah

    NARCIS (Netherlands)

    Gandiwa, E.

    2014-01-01

    Understanding factors influencing large herbivore densities and distribution in terrestrial ecosystems is a fundamental goal of ecology. This study examined environmental factors influencing the density and distribution of wild large herbivores in Gonarezhou National Park, Zimbabwe. Vegetation and s

  16. Above- and belowground insect herbivores differentially affect soil nematode communities in species-rich plant communities

    NARCIS (Netherlands)

    Deyn, de G.B.; Ruijven, van J.; Raaijmakers, C.E.; Ruiter, de P.C.; Putten, van der W.H.

    2007-01-01

    Interactions between above- and belowground invertebrate herbivores alter plant diversity, however, little is known on how these effects may influence higher trophic level organisms belowground. Here we explore whether above- and belowground invertebrate herbivores which alter plant community divers

  17. Selenium hyperaccumulation offers protection from cell disruptor herbivores

    Directory of Open Access Journals (Sweden)

    Quinn Colin F

    2010-08-01

    Full Text Available Abstract Background Hyperaccumulation, the rare capacity of certain plant species to accumulate toxic trace elements to levels several orders of magnitude higher than other species growing on the same site, is thought to be an elemental defense mechanism against herbivores and pathogens. Previous research has shown that selenium (Se hyperaccumulation protects plants from a variety of herbivores and pathogens. Selenium hyperaccumulating plants sequester Se in discrete locations in the leaf periphery, making them potentially more susceptible to some herbivore feeding modes than others. In this study we investigate the protective function of Se in the Se hyperaccumulators Stanleya pinnata and Astragalus bisulcatus against two cell disrupting herbivores, the western flower thrips (Frankliniella occidentalis and the two-spotted spider mite (Tetranychus urticae. Results Astragalus bisulcatus and S. pinnata with high Se concentrations (greater than 650 mg Se kg-1 were less subject to thrips herbivory than plants with low Se levels (less than 150 mg Se kg-1. Furthermore, in plants containing elevated Se levels, leaves with higher concentrations of Se suffered less herbivory than leaves with less Se. Spider mites also preferred to feed on low-Se A. bisulcatus and S. pinnata plants rather than high-Se plants. Spider mite populations on A. bisulcatus decreased after plants were given a higher concentration of Se. Interestingly, spider mites could colonize A. bisulcatus plants containing up to 200 mg Se kg-1 dry weight, concentrations which are toxic to many other herbivores. Selenium distribution and speciation studies using micro-focused X-ray fluorescence (μXRF mapping and Se K-edge X-ray absorption spectroscopy revealed that the spider mites accumulated primarily methylselenocysteine, the relatively non-toxic form of Se that is also the predominant form of Se in hyperaccumulators. Conclusions This is the first reported study investigating the

  18. Niche Segregation between Wild and Domestic Herbivores in Chilean Patagonia

    OpenAIRE

    Esperanza C Iranzo; Juan Traba; Pablo Acebes; Benito A González; Cristina Mata; Estades, Cristián F.; Malo, Juan E.

    2013-01-01

    Competition arises when two co-occuring species share a limiting resource. Potential for competition is higher when species have coexisted for a short time, as it is the case for herbivores and livestock introduced in natural systems. Sheep, introduced in the late 19(th) century in Patagonia, bear a great resemblance in size and diet to the guanaco, the main native herbivore in Patagonia. In such circumstances, it could be expected that the two species compete and one of them could be displac...

  19. Tracking the global dispersal of a cosmopolitan insect pest, the peach potato aphid

    Directory of Open Access Journals (Sweden)

    Kasprowicz Louise

    2009-05-01

    Full Text Available Abstract Background Global commerce and human transportation are responsible for the range expansion of various insect pests such as the plant sucking aphids. High resolution DNA markers provide the opportunity to examine the genetic structure of aphid populations, identify aphid genotypes and infer their evolutionary history and routes of expansion which is of value in developing management strategies. One of the most widespread aphid species is the peach-potato aphid Myzus persicae, which is considered as a serious pest on various crops in many parts of the world. The present study examined the genetic variation of this aphid at a world scale and then related this to distribution patterns. In particular, 197 aphid parthenogenetic lineages from around the world were analysed with six microsatellite loci. Results Bayesian clustering and admixture analysis split the aphid genotypes into three genetic clusters: European M. persicae persicae, New Zealand M. persicae persicae and Global M. persicae nicotianae. This partition was supported by FST and genetic distance analyses. The results showed two further points, a possible connection between genotypes found in the UK and New Zealand and globalization of nicotianae associated with colonisation of regions where tobacco is not cultivated. In addition, we report the presence of geographically widespread clones and for the first time the presence of a nicotianae genotype in the Old and New World. Lastly, heterozygote deficiency was detected in some sexual and asexual populations. Conclusion The study revealed important genetic variation among the aphid populations we examined and this was partitioned according to region and host-plant. Clonal selection and gene flow between sexual and asexual lineages are important factors shaping the genetic structure of the aphid populations. In addition, the results reflected the globalization of two subspecies of M. persicae with successful clones being spread at

  20. Tracking the global dispersal of a cosmopolitan insect pest, the peach potato aphid

    Science.gov (United States)

    Margaritopoulos, John T; Kasprowicz, Louise; Malloch, Gaynor L; Fenton, Brian

    2009-01-01

    Background Global commerce and human transportation are responsible for the range expansion of various insect pests such as the plant sucking aphids. High resolution DNA markers provide the opportunity to examine the genetic structure of aphid populations, identify aphid genotypes and infer their evolutionary history and routes of expansion which is of value in developing management strategies. One of the most widespread aphid species is the peach-potato aphid Myzus persicae, which is considered as a serious pest on various crops in many parts of the world. The present study examined the genetic variation of this aphid at a world scale and then related this to distribution patterns. In particular, 197 aphid parthenogenetic lineages from around the world were analysed with six microsatellite loci. Results Bayesian clustering and admixture analysis split the aphid genotypes into three genetic clusters: European M. persicae persicae, New Zealand M. persicae persicae and Global M. persicae nicotianae. This partition was supported by FST and genetic distance analyses. The results showed two further points, a possible connection between genotypes found in the UK and New Zealand and globalization of nicotianae associated with colonisation of regions where tobacco is not cultivated. In addition, we report the presence of geographically widespread clones and for the first time the presence of a nicotianae genotype in the Old and New World. Lastly, heterozygote deficiency was detected in some sexual and asexual populations. Conclusion The study revealed important genetic variation among the aphid populations we examined and this was partitioned according to region and host-plant. Clonal selection and gene flow between sexual and asexual lineages are important factors shaping the genetic structure of the aphid populations. In addition, the results reflected the globalization of two subspecies of M. persicae with successful clones being spread at various scales throughout the

  1. Population dynamics of rose aphid Macrosiphum rosae L. on different cultivars of Rosa indica L. in Pakistan

    International Nuclear Information System (INIS)

    The research was carried out at the Pir Mehr Ali Shah-Arid Agriculture University, Rawalpindi research field area on rose plants for rose aphid populations during 2008-09. Data were recorded on weekly basis. Nymphs, winged and wingless adults were counted from leaves (upper, middle and lower leaves), buds and flowers by visual observation from tagged plants. Aphid populations start to develop in November and its population decline with decline in temperature in December. While its population started rising again at the end of February. Significantly more aphid populations were observed on Perfecta than other varieties; however, significantly few aphids were observed on Christan Diar. These studies revealed that farmers growing roses on a commercial scale should grow Christan Diar to avoid aphid attack. Maximum average number of aphid nymph, winged and wingeless adults on leaves, buds and flowers were 11.11, 4.97 and 10.13, respectively observed on Perfecta variety. (author)

  2. Aphids (Homoptera, Aphidodea inhabiting the trees Crataegus x media Bechst. in the urban green area. Part I. The population dynamics

    Directory of Open Access Journals (Sweden)

    Bożena Jaśkiwicz

    2013-12-01

    Full Text Available The studies were conducted in the years 1999-2001 in the green areas of Lublin, on the trees of Crataegus x media Bechst. The purpose of the studies was to establish the species composition and the population dynamics of aphids inhabiting hawthorn in the street and park sites. The studies found out the presence of four aphid species on the examined trees, namely Aphis pomi De Geer, aphids from the genus Dysaphis Börn., Ovatus crataegarius (Walk. and Rhopalosiphum insertum (Walk.. More aphid species and bigger populations were found in the street site (A as compa red with the park site (B.The weather conditions (air temperatures of over 30°C and stormy rainfalls limited the population of all aphid species. On the other hand, a mild winter and a warm spring with the rainfalls within the norm caused that the number of aphids decreased considerably.

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

    OpenAIRE

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

    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 ...

  4. Sugarcane Aphid (Hemiptera: Aphididae): Host Range and Sorghum Resistance Including Cross-Resistance From Greenbug Sources.

    Science.gov (United States)

    Armstrong, J Scott; Rooney, William L; Peterson, Gary C; Villenueva, Raul T; Brewer, Michael J; Sekula-Ortiz, Danielle

    2015-04-01

    The graminous host range and sources of sorghum [Sorghum bicolor (L.) Moench.] plant resistance, including cross-resistance from greenbug, Schizaphis graminum (Rondani), were studied for the newly emerging sugarcane aphid, Melanaphis sacchari (Zehntner), in greenhouse no-choice experiments and field evaluations. The sugarcane aphid could not survive on field corn, Zea mays (L.), Teff grass, Eragrostis tef (Zucc.), proso millet, Panicum miliaceum L., barley, Hordeum vulgare L., and rye, Secale cereale L. Only sorghum genotypes served as hosts including Johnsongrass, Sorghum halepense (L.), a highly suitable noncrop host that generates high numbers of sugarcane aphid and maintains moderate phenotypic injury. The greenbug-resistant parental line RTx2783 that is resistant to greenbug biotypes C and E was resistant to sugarcane aphid in both greenhouse and field tests, while PI 55607 greenbug resistant to biotypes B, C, and E was highly susceptible. PI 55610 that is greenbug resistant to biotypes B, C, and E maintained moderate resistance to the sugarcane aphid, while greenbug-resistant PI 264453 was highly susceptible to sugarcane aphid. Two lines and two hybrids from the Texas A&M breeding program B11070, B11070, AB11055-WF1-CS1/RTx436, and AB11055-WF1-CS1/RTx437 were highly resistant to sugarcane aphid, as were parental types SC110, SC170, and South African lines Ent62/SADC, (Macia/TAM428)-LL9, (SV1*Sima/IS23250)-LG15. Tam428, a parental line that previously showed moderate resistance in South Africa and India, also showed moderate resistance in these evaluations. Overall, 9 of 20 parental sorghum entries tested for phenotypic damage in the field resulted in good resistance to the sugarcane aphid and should be utilized in breeding programs that develop agronomically acceptable sorghums for the southern regions of the United States.

  5. Species diversity and abundance of aphids and their natural enemies in a crop association

    OpenAIRE

    Chevalier Mendes Lopes, Thomas; Hatt, Séverin; Starý, Petr; JAPOSHVILI, George; Francis, Frédéric

    2015-01-01

    Crop associations can be efficient to reduce aphid populations, by disrupting the visual and olfactory location of host plants. However, increasing the chemical and structural complexity of vegetation can also decrease the searching efficiency of predators and parasitoids, which are not always more abundant in complex habitats. Using attractive semiochemicals such as methyl salicylate (MeSA) combined with a crop association seems promising to maximise aphid control. We compared the abundances...

  6. Selective and Irreversible Inhibitors of Aphid Acetylcholinesterases: Steps Toward Human-Safe Insecticides

    OpenAIRE

    Yuan-Ping Pang; Singh, Sanjay K.; Yang Gao; T Leon Lassiter; MISHRA, Rajesh K.; Kun Yan Zhu; Stephen Brimijoin

    2009-01-01

    Aphids, among the most destructive insects to world agriculture, are mainly controlled by organophosphate insecticides that disable the catalytic serine residue of acetylcholinesterase (AChE). Because these agents also affect vertebrate AChEs, they are toxic to non-target species including humans and birds. We previously reported that a cysteine residue (Cys), found at the AChE active site in aphids and other insects but not mammals, might serve as a target for insect-selective pesticides. Ho...

  7. Deep sequencing of the transcriptomes of soybean aphid and associated endosymbionts.

    Directory of Open Access Journals (Sweden)

    Sijun Liu

    Full Text Available BACKGROUND: The soybean aphid has significantly impacted soybean production in the U.S. Transcriptomic analyses were conducted for further insight into leads for potential novel management strategies. METHODOLOGY/PRINCIPAL FINDINGS: Transcriptomic data were generated from whole aphids and from 2,000 aphid guts using an Illumina GAII sequencer. The sequence data were assembled de novo using the Velvet assembler. In addition to providing a general overview, we demonstrate (i the use of the Multiple-k/Multiple-C method for de novo assembly of short read sequences, followed by BLAST annotation of contigs for increased transcript identification: From 400,000 contigs analyzed, 16,257 non-redundant BLAST hits were identified; (ii analysis of species distributions of top non-redundant hits: 80% of BLAST hits (minimum e-value of 1.0-E3 were to the pea aphid or other aphid species, representing about half of the pea aphid genes; (iii comparison of relative depth of sequence coverage to relative transcript abundance for genes with high (membrane alanyl aminopeptidase N or low transcript abundance; (iv analysis of the Buchnera transcriptome: Transcripts from 57.6% of the genes from Buchnera aphidicola were identified; (v identification of Arsenophonus and Wolbachia as potential secondary endosymbionts; (vi alignment of full length sequences from RNA-seq data for the putative salivary gland protein C002, the silencing of which has potential for aphid management, and the putative Bacillus thuringiensis Cry toxin receptors, aminopeptidase N and alkaline phosphatase. CONCLUSIONS/SIGNIFICANCE: THIS STUDY PROVIDES THE MOST COMPREHENSIVE DATA SET TO DATE FOR SOYBEAN APHID GENE EXPRESSION: This work also illustrates the utility of short-read transcriptome sequencing and the Multiple-k/Multiple-C method followed by BLAST annotation for rapid identification of target genes for organisms for which reference genome sequences are not available, and extends the utility

  8. Distributional congruence of mammalian herbivores in the Trans-Himalayan Mountains

    OpenAIRE

    Namgail, T.; Wieren, van, S.E.; Prins, H.H.T

    2013-01-01

    Large-scale distribution and diversity patterns of mammalian herbivores, especially less charismatic species in alpine environments remain little understood. We studied distributional congruence of mammalian herbivores in the Trans-Himalayan region of Ladakh to see if the distributions of less prominent and smaller herbivores can be determined from those of larger and more prominent herbivores like ungulates. Using a similarity index, we assessed shared distributions of species in 20x20 km2 g...

  9. Influence of polyploidy on insect herbivores of native and invasive genotypes of Solidago gigantea (Asteraceae)

    OpenAIRE

    Helen M. Hull-Sanders; Johnson, Robert H.; Owen, Heather A.; Meyer, Gretchen A.

    2009-01-01

    Herbivores are sensitive to the genetic structure of plant populations, as genetics underlies plant phenotype and host quality. Polyploidy is a widespread feature of angiosperm genomes, yet few studies have examined how polyploidy influences herbivores. Introduction to new ranges, with consequent changes in selective regimes, can lead to evolution of changes in plant defensive characteristics and also affect herbivores. Here, we examine how insect herbivores respond to polyploidy in Solidago ...

  10. Community- Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance

    OpenAIRE

    Ilja Sonnemann; Hans Pfestorf; Florian Jeltsch; Susanne Wurst

    2015-01-01

    Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calc...

  11. The importance of phenology in studies of plant-herbivore-parasitoid interactions

    OpenAIRE

    Fei, Minghui

    2016-01-01

    Thesis title: The importance of phenology in studies of plant-herbivore-parasitoid interactions Author: Minghui Fei Abstract As food resources of herbivorous insects, the quality and quantity of plants can directly affect the performance of herbivorous insects and indirectly affect the performance of natural enemies of the herbivorous insects. In nature, plant quality and quantity are dynamic and can change in individual plants over the course of a single growing season. Many multivoltine ins...

  12. Methodology of rearing of viruliferous population of aphid Rhopalosiphum padi, as a vector of Barley yellow dwarf virus (BYDV)

    OpenAIRE

    Štolcová, Jindra; Červená, Zuzana; Bártová, Šárka; Chrpová, Jana; Kumar, Jiban

    2012-01-01

    The methodology describes innovative procedures of rearing virulent population of Rhopalosiphum padi aphids, as a vector of Barley yellow dwarf virus (BYDV), for artificial infections of cereals. The method is a modification of existing procedure used in our laboratory for this purpose. The advantage of present methodology includes more abundance of viruliferous aphids within shorter period and effective control against aphid predators than the earlier used methodology.

  13. Biological control of aphids in wheat and vegetable crops : a multi-approach case study in Shandong province (China)

    OpenAIRE

    Chevalier Mendes Lopes, Thomas; Bosquée, Emilie; Chen, Julian; Yong, Liu; Bragard, Claude; Francis, Frédéric

    2014-01-01

    This multi-approach study was conducted in the Shandong province (China) to assess the effectiveness of different biological control methods against aphids in wheat and vegetable crops. Three approaches were tested: (1) wheat/oilseed rape and wheat/pea associations, (2) potatoes/peas association, and (3) E-β-farnesene (aphid alarm pheromone) releasers in squashes under plastic tunnels. Aphids and aphidophagous beneficials were monitored by observations on plants. Wheat associations and E-β-fa...

  14. Richness and diversity of aphids (Homoptera, Aphididae) along an altitudinal gradient in the Serra do Mar, Paraná, Brazil

    OpenAIRE

    Crisleide Maria Lazzarotto; Sonia Maria Noemberg Lázzari

    1998-01-01

    The lack of bioecological studies on aphids in regions with complex floristic and faunistic structure, such as the Atlantic Tropical Rain Forest, lead to the initiation of this research. The objectives were to determine species richness and diversity of aphids and to investigate the influence of altitude and environmental perturbations on aphid populations. The collections were made with yellow pan traps at 11 sites with altitudes from -10 m to 1000 m above sea level (a.s.l.), in the Serra do...

  15. A new approach for the identification of aphid vectors (Hemiptera: Aphididae) of potato virus Y.

    Science.gov (United States)

    Pelletier, Y; Nie, X; Giguère, M A; Nanayakkara, U; Maw, E; Foottit, R

    2012-12-01

    Potato virus Y (PVY) is one of the most economically important viruses affecting potato crops worldwide. PVY can be transmitted from potato to potato by several aphid species, most of which do not colonize the potato crop. New methods including preservation of viral RNA on stylets of aphids collected from yellow pan trap samples, polymerase chain reaction detection of PVY from the stylets of one aphid, and aphid identification using DNA barcoding were used to identify possible PVY vectors from field samples. In total, 65 aphid taxa were identified from the samples that tested positive for PVY. Among those, 45 taxa had never been evaluated for their ability to transmit PVY, and 7 were previously labeled as nonvectors. These results demonstrated that the list of PVY vectors is likely longer than previously reported and that most (if not all) species of aphids could be considered as potential vectors. This premise has important implications in the management of PVY in seed potato production. PMID:23356053

  16. Activation of defense mechanism in wheat by polyphenol oxidase from aphid saliva.

    Science.gov (United States)

    Ma, Rui; Chen, Ju-Lian; Cheng, Deng-Fa; Sun, Jing-Rui

    2010-02-24

    The saliva of two cereal aphids, Sitobion avenae and Schizaphis graminum in third-instar nymphs, was collected after 24 h of feeding by 30 aphids, separately, on artificial diet sachets, and the salivary enzymes were determined. The result showed that polyphenol oxidase (PPO) existed in the saliva of both aphid species, and the enzymatic activities were 6.2 x 10(-3) U/g for S. avenae and 2.37 x 10(-1) U/g for S. graminum, revealing a 38-fold higher activity in the saliva of S. graminum than in the saliva of S. avenae. It was speculated that the higher PPO activity in S. graminum saliva was a contributing factor to the light yellow spot left on the feeding site of the wheat leaf by S. graminum; no such spot was left by S. avenae. After treatment of a wheat seedling with the saliva of S. avenae and S. graminum and PPO at the concentration of aphid saliva, transcript profiling data showed that aphid saliva and PPO significantly induced expression of the genes aos and fps. Because genes aos and fps encode the key enzymes in the defense signal pathways jasmonic acid and terpene signal pathways, respectively, it was deduced that PPO from aphid saliva, as the main elicitor, triggers an appropriate defense response in wheat through jasmonic acid and terpene signal pathways. PMID:20112908

  17. Winged Pea Aphids Can Modify Phototaxis in Different Development Stages to Assist Their Host Distribution.

    Science.gov (United States)

    Zhang, Yi; Wang, Xing-Xing; Jing, Xiangfeng; Tian, Hong-Gang; Liu, Tong-Xian

    2016-01-01

    The pea aphid, Acyrthosiphon pisum (Harris) (Hemiptera: Aphididae), shows wing polyphenism (winged and wingless morphs) in its life cycle. The winged morph is adapted for dispersal; its two developmental adult stages (for dispersal and reproduction) are based on its breeding periods. The two morphs show different phototactic behavior and the winged can change its preference to light according to the developmental stages. To determine the mechanism and ecological functions of phototaxis for A. pisum, we first investigated the phototaxis of the two aphid morphs at different stages and analyzed the phototactic response to lights of different wavelengths; the correlation between alate fecundity and their phototactic behaviors were then studied. Finally, we focused on the possible functions of phototaxis in aphid host location and distribution in combination with gravitaxis behaviors. Negative phototaxis was found for breeding winged adults but all the other stages of both winged and wingless morphs showed positive phototaxis. The reactions of the aphids to different wavelengths were also different. Nymph production in winged adults showed negative correlation to phototaxis. The dopamine pathway was possibly involved in these behavior modifications. We speculated that winged adults can use light for dispersal in the early dispersal stage and for position holding in the breeding stage. Based on our results, we assume that light signals are important for aphid dispersal and distribution, and are also essential for the pea aphids to cope with environmental changes. PMID:27531980

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

    Directory of Open Access Journals (Sweden)

    Hubert Sytykiewicz

    Full Text Available 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.

  19. 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

  20. In vitro interactions of the aphid endosymbiotic SymL chaperonin with barley yellow dwarf virus.

    Science.gov (United States)

    Filichkin, S A; Brumfield, S; Filichkin, T P; Young, M J

    1997-01-01

    Barley yellow dwarf virus (BYDV)-vector relationships suggest that there are specific interactions between BYDV virions and the aphid's cellular components. However, little is known about vector factors that mediate virion recognition, cellular trafficking, and accumulation within the aphid. Symbionins are molecular chaperonins produced by intracellular endosymbiotic bacteria and are the most abundant proteins found in aphids. To elucidate the potential role of symbionins in BYDV transmission, we have isolated and characterized two new symbionin symL genes encoded by the endosymbionts which are harbored by the BYDV aphid vectors Rhopalosiphum padi and Sitobion avenae. Endosymbiont symL-encoded proteins have extensive homology with the pea aphid SymL and Escherichia coli GroEL chaperonin. Recombinant and native SymL proteins can be assembled into oligomeric complexes which are similar to the GroEL oligomer. R. padi SymL protein demonstrates an in vitro binding affinity for BYDV and its recombinant readthrough polypeptide. In contrast to the R. padi SymL, the closely related GroEL does not exhibit a significant binding affinity either for BYDV or for its recombinant readthrough polypeptide. Comparative sequence analysis between SymL and GroEL was used to identify potential SymL-BYDV binding sites. Affinity binding of SymL to BYDV in vitro suggests a potential involvement of endosymbiotic chaperonins in interactions with virions during their trafficking through the aphid. PMID:8985385

  1. Impact of different-sized herbivores on recruitment opportunities for subordinate herbs in grasslands

    NARCIS (Netherlands)

    Bakker, Elisabeth S.; Olff, Han

    2003-01-01

    Potential effects of herbivores on plant species diversity depend on herbivore size, species and density. In this study we examine the effect of different-sized herbivores (cattle and rabbits) on recruitment of subordinate herbs in grasslands. We show that in a grazed floodplain, grassland plant spe

  2. Unbiased Transcriptional Comparisons of Generalist and Specialist Herbivores Feeding on Progressively Defenseless Nicotiana attenuata Plants

    NARCIS (Netherlands)

    G. Govind; O. Mittapalli; T. Griebel; S. Allmann; S. Böcker; I.T. Baldwin

    2010-01-01

    Background Herbivore feeding elicits dramatic increases in defenses, most of which require jasmonate (JA) signaling, and against which specialist herbivores are thought to be better adapted than generalist herbivores. Unbiased transcriptional analyses of how neonate larvae cope with these induced pl

  3. Intraspecific variation in a generalist herbivore accounts for differential induction and impact of host plant defences

    NARCIS (Netherlands)

    M.R. Kant; M.W. Sabelis; M.A. Haring; R.C. Schuurink

    2008-01-01

    Plants and herbivores are thought to be engaged in a coevolutionary arms race: rising frequencies of plants with anti-herbivore defences exert pressure on herbivores to resist or circumvent these defences and vice versa. Owing to its frequency-dependent character, the arms race hypothesis predicts t

  4. Alternaria toxin-induced resistance against rose aphids and olfactory response of aphids to toxin-induced volatiles of rose plants

    Institute of Scientific and Technical Information of China (English)

    Fa-zhong YANG; Li LI; Bin YANG

    2012-01-01

    The search for active toxins for managing weeds or plant diseases is believed to be a promising avenue of investigation.However,the effects of Alternaria toxins on insects have just begun to be investigated.Bioactivities of toxins from four strains of Alternaria alternata on Rosa chinensis and rose aphid Macrosiphum rosivorum were tested in the present study.At a concentration of 50.0 μg/ml,the crude extract (toxin) of strain 7484 was found not to be harmful to rose plants with excised leaf-puncture method (P≥0.079),and rose plants showed enhanced resistance to rose aphids when this Alternaria toxin was sprayed on the plants (P≤0.001).However,this toxin caused no detrimental effects on aphids in insecticidal bioassay at a concentration of 10.0 to 160.0 μg/ml (P≥0.096).Therefore,the Alternaria toxin had significantly induced the resistance of rose plants against rose aphids,demonstrating that the resistance mechanism triggered by the Altemaria toxin in the rose plant may also be used by the plant to defend itself against insects.Further bioassays aimed to discover the olfactory responses of aphids to the toxin-induced volatiles of host plants.The aphids were significantly more attracted to both volatiles emitted and collected from control rose plants than to both volatiles emitted and collected from the toxin-treated rose plants (P≤0.014).This result showed that the toxin-induced resistance related to the volatile changes of host plants.

  5. Hoverfly preference for high honeydew amounts creates enemy-free space for aphids colonizing novel host plants.

    Science.gov (United States)

    Vosteen, Ilka; Gershenzon, Jonathan; Kunert, Grit

    2016-09-01

    The existence of an enemy-free space can play an important role in aphid host race formation processes, but little is known about the mechanisms that create an area of low predation pressure on particular host plants. In this paper, we identify a mechanism generating lower predation pressure that promotes the maintenance of the different host races of the pea aphid (Acyrthosiphon pisum) complex, a well-studied model for ecological speciation. The pea aphid consists of at least 15 genetically distinct host races which are native to specific host plants of the legume family, but can all develop on the universal host plant Vicia faba. Previous work showed that hoverfly (Episyrphus balteatus) oviposition preferences contribute to the enemy-free space that helps to maintain the different pea aphid host races, and that higher amounts of honeydew are more attractive to ovipositing hoverflies. Here we demonstrated that aphid honeydew is produced in large amounts when aphid reproduction rate was highest, and is an important oviposition cue for hoverflies under field conditions. However, on less suitable host plants, where honeydew production is reduced, pea aphids enjoy lower predation rates. A reduction in enemy pressure can mitigate the performance disadvantages of aphids colonizing a novel host and probably plays an important role in pea aphid host race formation. PMID:27328648

  6. Characterization of the natural enemy community attacking cotton aphid in the Bt cotton ecosystem in Northern China.

    Science.gov (United States)

    Ali, Abid; Desneux, Nicolas; Lu, Yanhui; Liu, Bing; Wu, Kongming

    2016-01-01

    Planting Bt cotton in China since 1997 has led to important changes in the natural enemy communities occurring in cotton, however their specific effect on suppressing the cotton aphids (being notorious in conventional cotton ecosystem) has not been fully documented yet. We observed strong evidence for top-down control of the aphid population, e.g. the control efficiency of natural enemies on cotton aphid increased significantly in open field cages compared to exclusion cages, accounted for 60.2, 87.2 and 76.7% in 2011, 2012 and 2013 season, respectively. The cotton aphid populations peaked in early June to late July (early and middle growth stages) in open field cotton survey from 2011 to 2013. The population densities of cotton aphids and natural enemies were highest on middle growth stage while lowest densities were recorded on late stage for aphids and on early plant stage for natural enemies. Aphid parasitoids (Trioxys spp., Aphidius gifuensis), coccinellids and spiders were key natural enemies of cotton aphid. Briefly, natural enemies can suppress aphid population increase from early to middle plant growth stages by providing biocontrol services in Chinese Bt cotton. PMID:27075171

  7. Hoverfly preference for high honeydew amounts creates enemy-free space for aphids colonizing novel host plants.

    Science.gov (United States)

    Vosteen, Ilka; Gershenzon, Jonathan; Kunert, Grit

    2016-09-01

    The existence of an enemy-free space can play an important role in aphid host race formation processes, but little is known about the mechanisms that create an area of low predation pressure on particular host plants. In this paper, we identify a mechanism generating lower predation pressure that promotes the maintenance of the different host races of the pea aphid (Acyrthosiphon pisum) complex, a well-studied model for ecological speciation. The pea aphid consists of at least 15 genetically distinct host races which are native to specific host plants of the legume family, but can all develop on the universal host plant Vicia faba. Previous work showed that hoverfly (Episyrphus balteatus) oviposition preferences contribute to the enemy-free space that helps to maintain the different pea aphid host races, and that higher amounts of honeydew are more attractive to ovipositing hoverflies. Here we demonstrated that aphid honeydew is produced in large amounts when aphid reproduction rate was highest, and is an important oviposition cue for hoverflies under field conditions. However, on less suitable host plants, where honeydew production is reduced, pea aphids enjoy lower predation rates. A reduction in enemy pressure can mitigate the performance disadvantages of aphids colonizing a novel host and probably plays an important role in pea aphid host race formation.

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

    Directory of Open Access Journals (Sweden)

    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.

  9. A Study of Tapping by the Unaffected Finger of Patients Presenting with Central and Peripheral Nerve Damage

    Directory of Open Access Journals (Sweden)

    Lingli eZhang

    2015-05-01

    Full Text Available Aim: Whether the unaffected function of the hand of patients presenting with nerve injury is affected remains inconclusive. We aimed to evaluate whether there are differences in finger tapping following central or peripheral nerve injury compared with the unaffected hand and the ipsilateral hand of a healthy subject.Methods: 30 right brain stroke patients with hemiplegia, 30 left arm peripheral nerve injury cases and 60 healthy people were selected. We tested finger tapping of the right hands, and each subject performed the test twice.Results: Finger tapping following peripheral nerve injury as compared with the unaffected hand and the dominant hand of a healthy person was significantly higher than was found for central nerve injury (P<0.05. Finger tapping of the male peripheral group’s unaffected hand and the control group’s dominant hand was significantly higher than the central group (P<0.001. However, finger tapping of the female control group’s dominant hand was markedly higher than the central group’s unaffected hand (P<0.01, P=0.002, the peripheral group’s unaffected hand (P<0.05, P=0.034. Conclusion: The unaffected function of the hand of patients with central and peripheral nerve injury was different as compared with the ipsilateral hand of healthy individuals. The rehabilitation therapist should intensify the practice of normal upper limb fine activities and coordination of the patient.

  10. Aquatic herbivores facilitate the emission of methane from wetlands

    NARCIS (Netherlands)

    Dingemans, B.J.J.; Bakker, E.S.; Bodelier, P.L.E.

    2011-01-01

    Wetlands are significant sources of atmospheric methane. Methane produced by microbes enters roots and escapes to the atmosphere through the shoots of emergent wetland plants. Herbivorous birds graze on helophytes, but their effect on methane emission remains unknown. We hypothesized that grazing on

  11. Herbivores and nutrients control grassland plant diversity via light limitation.

    Energy Technology Data Exchange (ETDEWEB)

    Borer, Elizabeth T. [Department of Ecology, Evolution, and Behavior, University of Minnesota; et al, et al

    2014-01-01

    Human alterations to nutrient cycles1,2 and herbivore communities3–7 are affecting global biodiversity dramatically2. Ecological theory predicts these changes should be strongly counteractive: nutrient addition drives plant species loss through intensified competition for light, whereas herbivores prevent competitive exclusion by increasing ground-level light, particularly in productive systems8,9. Here we use experimental data spanning a globally relevant range of conditions to test the hypothesis that herbaceous plant species losses caused by eutrophication may be offset by increased light availability due to herbivory. This experiment, replicated in 40 grasslands on 6 continents, demonstrates that nutrients and herbivores can serve as counteracting forces to control local plant diversity through light limitation, independent of site productivity, soil nitrogen, herbivore type and climate. Nutrient addition consistently reduced local diversity through light limitation, and herbivory rescued diversity at sites where it alleviated light limitation. Thus, species loss from anthropogenic eutrophication can be ameliorated in grasslands where herbivory increases ground-level light.

  12. African Wildlife Policy : Protecting Wildlife Herbivores on Private Game Ranches

    NARCIS (Netherlands)

    Kinyua, P.; Kooten, van G.C.; Bulte, E.H.

    2000-01-01

    In large parts of Africa, wildlife herbivores spill over onto private lands, competing with domestic livestock for forage resources. To encourage private landowners to take into account the externality benefits of wildlife, game cropping is increasingly considered as an important component of conser

  13. Plant-carnivore mutualism through herbivore-induced carnivore attractants.

    NARCIS (Netherlands)

    Takabayashi, J.; Dicke, M.

    1996-01-01

    Plants and carnivorous arthropods can interact mutualistically. A recent discovery is that such mutualisms can be mediated by volatile compounds — produced by plants in response to herbivore damage — that attract carnivores. However, after emission of these attractants, the plant has no control over

  14. Are exotic herbivores better competitors? A meta-analysis.

    Science.gov (United States)

    Radville, Laura; Gonda-King, Liahna; Gómez, Sara; Kaplan, Ian; Preisser, Evan L

    2014-01-01

    Competition plays an important role in structuring the community dynamics of phytophagous insects. As the number and impact of biological invasions increase, it has become increasingly important to determine whether competitive differences exist between native and exotic insects. We conducted a meta-analysis to test the hypothesis that native/ exotic status affects the outcome of herbivore competition. Specifically, we used data from 160 published studies to assess plant-mediated competition in phytophagous insects. For each pair of competing herbivores, we determined the native range and coevolutionary history of each herbivore and host plant. Plant-mediated competition occurred frequently, but neither native nor exotic insects were consistently better competitors. Spatial separation reduced competition in native insects but showed little effect on exotics. Temporal separation negatively impacted native insects but did not affect competition in exotics. Insects that coevolved with their host plant were more affected by interspecific competition than herbivores that lacked a coevolutionary history. Insects that have not coevolved with their host plant may be at a competitive advantage if they overcome plant defenses. As native/exotic status does not consistently predict outcomes of competitive interactions, plant-insect coevolutionary history should be considered in studies of competition.

  15. Herbivore-induced resistance against microbial pathogens in Arabidopsis

    NARCIS (Netherlands)

    Vos, de M.; Zaanen, van W.; Koornneef, A.; Korzelius, J.P.; Dicke, M.; Loon, van L.C.; Pieterse, C.M.J.

    2006-01-01

    Caterpillars of the herbivore Pieris rapae stimulate the production of jasmonic acid (JA) and ethylene (ET) in Arabidopsis (Arabidopsis thaliana) and trigger a defense response that affects insect performance on systemic tissues. To investigate the spectrum of effectiveness of P. rapae-induced resis

  16. Maintenance of genetic diversity through plant-herbivore interactions

    OpenAIRE

    Gloss, Andrew D.; Dittrich, Anna C. Nelson; Goldman-Huertas, Benjamin; Whiteman, Noah K.

    2013-01-01

    Identifying the factors governing the maintenance of genetic variation is a central challenge in evolutionary biology. New genomic data, methods and conceptual advances provide increasing evidence that balancing selection, mediated by antagonistic species interactions, maintains functionally-important genetic variation within species and natural populations. Because diverse interactions between plants and herbivorous insects dominate terrestrial communities, they provide excellent systems to ...

  17. Resilience in plant-herbivore networks during secondary succession.

    Directory of Open Access Journals (Sweden)

    Edith Villa-Galaviz

    Full Text Available Extensive land-use change in the tropics has produced a mosaic of successional forests within an agricultural and cattle-pasture matrix. Post-disturbance biodiversity assessments have found that regeneration speed depends upon propagule availability and the intensity and duration of disturbance. However, reestablishment of species interactions is still poorly understood and this limits our understanding of the anthropogenic impacts upon ecosystem resilience. This is the first investigation that evaluates plant-herbivore interaction networks during secondary succession. In particular we investigated succession in a Mexican tropical dry forest using data of caterpillar associations with plants during 2007-2010. Plant-herbivore networks showed high resilience. We found no differences in most network descriptors between secondary and mature forest and only recently abandoned fields were found to be different. No significant nestedness or modularity network structure was found. Plant-herbivore network properties appear to quickly reestablish after perturbation, despite differences in species richness and composition. This study provides some valuable guidelines for the implement of restoration efforts that can enhance ecological processes such as the interaction between plants and their herbivores.

  18. Genomics of adaptation to host-plants in herbivorous insects.

    Science.gov (United States)

    Simon, Jean-Christophe; d'Alençon, Emmanuelle; Guy, Endrick; Jacquin-Joly, Emmanuelle; Jaquiéry, Julie; Nouhaud, Pierre; Peccoud, Jean; Sugio, Akiko; Streiff, Réjane

    2015-11-01

    Herbivorous insects represent the most species-rich lineages of metazoans. The high rate of diversification in herbivorous insects is thought to result from their specialization to distinct host-plants, which creates conditions favorable for the build-up of reproductive isolation and speciation. These conditions rely on constraints against the optimal use of a wide range of plant species, as each must constitute a viable food resource, oviposition site and mating site for an insect. Utilization of plants involves many essential traits of herbivorous insects, as they locate and select their hosts, overcome their defenses and acquire nutrients while avoiding intoxication. Although advances in understanding insect-plant molecular interactions have been limited by the complexity of insect traits involved in host use and the lack of genomic resources and functional tools, recent studies at the molecular level, combined with large-scale genomics studies at population and species levels, are revealing the genetic underpinning of plant specialization and adaptive divergence in non-model insect herbivores. Here, we review the recent advances in the genomics of plant adaptation in hemipterans and lepidopterans, two major insect orders, each of which includes a large number of crop pests. We focus on how genomics and post-genomics have improved our understanding of the mechanisms involved in insect-plant interactions by reviewing recent molecular discoveries in sensing, feeding, digesting and detoxifying strategies. We also present the outcomes of large-scale genomics approaches aimed at identifying loci potentially involved in plant adaptation in these insects.

  19. A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack

    NARCIS (Netherlands)

    Huber, M.; Epping, Janina; Schulze Gronover, C.; Fricke, Julia; Aziz, Zohra; Brillatz, Théo; Swyers, Michael; Kollner, T.G.; Vogel, H.; Hammerbacher, Almuth; Triebwasser-Freese, Daniella; Robert, Christelle A.M.; Verhoeven, K.J.F.; Preite, V.; Gershenzon, J.; Erb, M.

    2016-01-01

    Plants produce large amounts of secondary metabolites in their shoots and roots and store them in specialized secretory structures. Although secondary metabolites and their secretory structures are commonly assumed to have a defensive function, evidence that they benefit plant fitness under herbivor

  20. Nitrogen transfer between herbivores and their forage species

    NARCIS (Netherlands)

    Sjogersten, Sofie; Kuijper, Dries P. J.; van der Wal, Rene; Loonen, Maarten J. J. E.; Huiskes, Ad H. L.; Woodin, Sarah J.

    2010-01-01

    Herbivores may increase the productivity of forage plants; however, this depends on the return of nutrients from faeces to the forage plants. The aim of this study was to test if nitrogen (N) from faeces is available to forage plants and whether the return of nutrients differs between plant species

  1. Recognition of facial emotion and affective prosody in children with ASD (+ADHD) and their unaffected siblings.

    Science.gov (United States)

    Oerlemans, Anoek M; van der Meer, Jolanda M J; van Steijn, Daphne J; de Ruiter, Saskia W; de Bruijn, Yvette G E; de Sonneville, Leo M J; Buitelaar, Jan K; Rommelse, Nanda N J

    2014-05-01

    Autism is a highly heritable and clinically heterogeneous neuropsychiatric disorder that frequently co-occurs with other psychopathologies, such as attention-deficit/hyperactivity disorder (ADHD). An approach to parse heterogeneity is by forming more homogeneous subgroups of autism spectrum disorder (ASD) patients based on their underlying, heritable cognitive vulnerabilities (endophenotypes). Emotion recognition is a likely endophenotypic candidate for ASD and possibly for ADHD. Therefore, this study aimed to examine whether emotion recognition is a viable endophenotypic candidate for ASD and to assess the impact of comorbid ADHD in this context. A total of 90 children with ASD (43 with and 47 without ADHD), 79 ASD unaffected siblings, and 139 controls aged 6-13 years, were included to test recognition of facial emotion and affective prosody. Our results revealed that the recognition of both facial emotion and affective prosody was impaired in children with ASD and aggravated by the presence of ADHD. The latter could only be partly explained by typical ADHD cognitive deficits, such as inhibitory and attentional problems. The performance of unaffected siblings could overall be considered at an intermediate level, performing somewhat worse than the controls and better than the ASD probands. Our findings suggest that emotion recognition might be a viable endophenotype in ASD and a fruitful target in future family studies of the genetic contribution to ASD and comorbid ADHD. Furthermore, our results suggest that children with comorbid ASD and ADHD are at highest risk for emotion recognition problems.

  2. Three dysconnectivity patterns in treatment-resistant schizophrenia patients and their unaffected siblings

    Directory of Open Access Journals (Sweden)

    Jicai Wang

    2015-01-01

    Full Text Available Among individuals diagnosed with schizophrenia, approximately 20%–33% are recognized as treatment-resistant schizophrenia (TRS patients. These TRS patients suffer more severely from the disease but struggle to benefit from existing antipsychotic treatments. A few recent studies suggested that schizophrenia may be caused by impaired synaptic plasticity that manifests as functional dysconnectivity in the brain, however, few of those studies focused on the functional connectivity changes in the brains of TRS groups. In this study, we compared the whole brain connectivity variations in TRS patients, their unaffected siblings, and healthy controls. Connectivity network features between and within the 116 automated anatomical labeling (AAL brain regions were calculated and compared using maps created with three contrasts: patient vs. control, patient vs. sibling, and sibling vs. control. To evaluate the predictive power of the selected features, we performed a multivariate classification approach. We also evaluated the influence of six important clinical measures (e.g. age, education level on the connectivity features. This study identified abnormal significant connectivity changes of three patterns in TRS patients and their unaffected siblings: 1 69 patient-specific connectivity (PCN; 2 102 shared connectivity (SCN; and 3 457 unshared connectivity (UCN. While the first two patterns were widely reported by previous non-TRS specific studies, we were among the first to report widespread significant connectivity differences between TRS patient groups and their healthy sibling groups. Observations of this study may provide new insights for the understanding of the neurophysiological mechanisms of TRS.

  3. The root herbivore history of the soil affects the productivity of a grassland plant community and determines plant response to new root herbivore attack.

    Directory of Open Access Journals (Sweden)

    Ilja Sonnemann

    Full Text Available Insect root herbivores can alter plant community structure by affecting the competitive ability of single plants. However, their effects can be modified by the soil environment. Root herbivory itself may induce changes in the soil biota community, and it has recently been shown that these changes can affect plant growth in a subsequent season or plant generation. However, so far it is not known whether these root herbivore history effects (i are detectable at the plant community level and/or (ii also determine plant species and plant community responses to new root herbivore attack. The present greenhouse study determined root herbivore history effects of click beetle larvae (Elateridae, Coleoptera, genus Agriotes in a model grassland plant community consisting of six common species (Achillea millefolium, Plantago lanceolata, Taraxacum officinale, Holcus lanatus, Poa pratensis, Trifolium repens. Root herbivore history effects were generated in a first phase of the experiment by growing the plant community in soil with or without Agriotes larvae, and investigated in a second phase by growing it again in the soils that were either Agriotes trained or not. The root herbivore history of the soil affected plant community productivity (but not composition, with communities growing in root herbivore trained soil producing more biomass than those growing in untrained soil. Additionally, it influenced the response of certain plant species to new root herbivore attack. Effects may partly be explained by herbivore-induced shifts in the community of arbuscular mycorrhizal fungi. The root herbivore history of the soil proved to be a stronger driver of plant growth on the community level than an actual root herbivore attack which did not affect plant community parameters. History effects have to be taken into account when predicting the impact of root herbivores on grasslands.

  4. Herbivore Preference for Native vs. Exotic Plants: Generalist Herbivores from Multiple Continents Prefer Exotic Plants That Are Evolutionarily Naïve

    OpenAIRE

    Wendy E Morrison; Mark E Hay

    2011-01-01

    Enemy release and biotic resistance are competing, but not mutually exclusive, hypotheses addressing the success or failure of non-native plants entering a new region. Enemy release predicts that exotic plants become invasive by escaping their co-adapted herbivores and by being unrecognized or unpalatable to native herbivores that have not been selected to consume them. In contrast, biotic resistance predicts that native generalist herbivores will suppress exotic plants that will not have bee...

  5. Water stress modulates soybean aphid performance, feeding behavior and virus transmission in soybean

    Directory of Open Access Journals (Sweden)

    Punya eNachappa

    2016-04-01

    Full Text Available Little is known about how water stress including drought and flooding modifies the ability of plants to resist simultaneous attack by insect feeding and transmission of insect-vectored pathogen. We analyzed insect population growth, feeding behaviors, virus transmission, and plant amino acid profiles and defense gene expression to characterize mechanisms underlying the interaction between water stress, soybean aphid and aphid-transmitted, Soybean mosaic virus, on soybean plants. Population growth of non-viruliferous aphids was reduced under drought stress and saturation, likely because the aphids spent less time feeding from the sieve element on these plants compared to well-watered plants. Water stress did not impact population growth of viruliferous aphids. However, virus incidence and transmission rate was lowest under drought stress and highest under saturated conditions since viruliferous aphids took the greatest amount time to puncture cells and transmit the virus under saturated conditions and lowest time under drought stress. Petiole exudates from drought-stressed plants had the highest level of total free amino acids including asparagine and valine that are critical for aphid performance. Aphids did not benefit from improved phloem sap quality as indicated by their lower densities on drought-stressed plants. Saturation, on the other hand, resulted in low amino acid content compared to all of the other treatments. Drought and saturation had significant and opposing effects on expression of marker genes involved in abscisic acid (ABA signaling. Drought alone significantly increased expression of ABA marker genes, which likely led to suppression of salicylic acid (SA- and jasmonic acid (JA-related genes. In contrast, ABA marker genes were down-regulated under saturation, while expression of SA- and JA-related genes was up-regulated. We propose that the apparent antagonism between ABA and SA/JA signaling pathways contributed to an increase

  6. Water Stress Modulates Soybean Aphid Performance, Feeding Behavior, and Virus Transmission in Soybean.

    Science.gov (United States)

    Nachappa, Punya; Culkin, Christopher T; Saya, Peter M; Han, Jinlong; Nalam, Vamsi J

    2016-01-01

    Little is known about how water stress including drought and flooding modifies the ability of plants to resist simultaneous attack by insect feeding and transmission of insect-vectored pathogen. We analyzed insect population growth, feeding behaviors, virus transmission, and plant amino acid profiles and defense gene expression to characterize mechanisms underlying the interaction between water stress, soybean aphid and aphid-transmitted, Soybean mosaic virus, on soybean plants. Population growth of non-viruliferous aphids was reduced under drought stress and saturation, likely because the aphids spent less time feeding from the sieve element on these plants compared to well-watered plants. Water stress did not impact population growth of viruliferous aphids. However, virus incidence and transmission rate was lowest under drought stress and highest under saturated conditions since viruliferous aphids took the greatest amount time to puncture cells and transmit the virus under saturated conditions and lowest time under drought stress. Petiole exudates from drought-stressed plants had the highest level of total free amino acids including asparagine and valine that are critical for aphid performance. Aphids did not benefit from improved phloem sap quality as indicated by their lower densities on drought-stressed plants. Saturation, on the other hand, resulted in low amino acid content compared to all of the other treatments. Drought and saturation had significant and opposing effects on expression of marker genes involved in abscisic acid (ABA) signaling. Drought alone significantly increased expression of ABA marker genes, which likely led to suppression of salicylic acid (SA)- and jasmonic acid (JA)-related genes. In contrast, ABA marker genes were down-regulated under saturation, while expression of SA- and JA-related genes was up-regulated. We propose that the apparent antagonism between ABA and SA/JA signaling pathways contributed to an increase in aphid

  7. Pest trade-offs in technology: reduced damage by caterpillars in Bt cotton benefits aphids

    OpenAIRE

    Hagenbucher, Steffen; Felix L Wäckers; Wettstein, Felix E.; Olson, Dawn M.; Ruberson, John R.; Romeis, Jörg

    2013-01-01

    The rapid adoption of genetically engineered (GE) plants that express insecticidal Cry proteins derived from Bacillus thuringiensis (Bt) has raised concerns about their potential impact on non-target organisms. This includes the possibility that non-target herbivores develop into pests. Although studies have now reported increased populations of non-target herbivores in Bt cotton, the underlying mechanisms are not fully understood. We propose that lack of herbivore-induced secondary metabolit...

  8. Potato tuber herbivory increases resistance to aboveground lepidopteran herbivores.

    Science.gov (United States)

    Kumar, Pavan; Ortiz, Erandi Vargas; Garrido, Etzel; Poveda, Katja; Jander, Georg

    2016-09-01

    Plants mediate interactions between aboveground and belowground herbivores. Although effects of root herbivory on foliar herbivores have been documented in several plant species, interactions between tuber-feeding herbivores and foliar herbivores are rarely investigated. We report that localized tuber damage by Tecia solanivora (Guatemalan tuber moth) larvae reduced aboveground Spodoptera exigua (beet armyworm) and Spodoptera frugiperda (fall armyworm) performance on Solanum tuberosum (potato). Conversely, S. exigua leaf damage had no noticeable effect on belowground T. solanivora performance. Tuber infestation by T. solanivora induced systemic plant defenses and elevated resistance to aboveground herbivores. Lipoxygenase 3 (Lox3), which contributes to the synthesis of plant defense signaling molecules, had higher transcript abundance in T. solanivora-infested leaves and tubers than in equivalent control samples. Foliar expression of the hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase (HQT) and 3-hydroxy-3-methylglutaryl CoA reductase I (HMGR1) genes, which are involved in chlorogenic acid and steroidal glycoalkaloid biosynthesis, respectively, also increased in response to tuber herbivory. Leaf metabolite profiling demonstrated the accumulation of unknown metabolites as well as the known potato defense compounds chlorogenic acid, α-solanine, and α-chaconine. When added to insect diet at concentrations similar to those found in potato leaves, chlorogenic acid, α-solanine, and α-chaconine all reduced S. exigua larval growth. Thus, despite the fact that tubers are a metabolic sink tissue, T. solanivora feeding elicits a systemic signal that induces aboveground resistance against S. exigua and S. frugiperda by increasing foliar abundance of defensive metabolites.

  9. Potato tuber herbivory increases resistance to aboveground lepidopteran herbivores.

    Science.gov (United States)

    Kumar, Pavan; Ortiz, Erandi Vargas; Garrido, Etzel; Poveda, Katja; Jander, Georg

    2016-09-01

    Plants mediate interactions between aboveground and belowground herbivores. Although effects of root herbivory on foliar herbivores have been documented in several plant species, interactions between tuber-feeding herbivores and foliar herbivores are rarely investigated. We report that localized tuber damage by Tecia solanivora (Guatemalan tuber moth) larvae reduced aboveground Spodoptera exigua (beet armyworm) and Spodoptera frugiperda (fall armyworm) performance on Solanum tuberosum (potato). Conversely, S. exigua leaf damage had no noticeable effect on belowground T. solanivora performance. Tuber infestation by T. solanivora induced systemic plant defenses and elevated resistance to aboveground herbivores. Lipoxygenase 3 (Lox3), which contributes to the synthesis of plant defense signaling molecules, had higher transcript abundance in T. solanivora-infested leaves and tubers than in equivalent control samples. Foliar expression of the hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase (HQT) and 3-hydroxy-3-methylglutaryl CoA reductase I (HMGR1) genes, which are involved in chlorogenic acid and steroidal glycoalkaloid biosynthesis, respectively, also increased in response to tuber herbivory. Leaf metabolite profiling demonstrated the accumulation of unknown metabolites as well as the known potato defense compounds chlorogenic acid, α-solanine, and α-chaconine. When added to insect diet at concentrations similar to those found in potato leaves, chlorogenic acid, α-solanine, and α-chaconine all reduced S. exigua larval growth. Thus, despite the fact that tubers are a metabolic sink tissue, T. solanivora feeding elicits a systemic signal that induces aboveground resistance against S. exigua and S. frugiperda by increasing foliar abundance of defensive metabolites. PMID:27147449

  10. Pollinator and herbivore attraction to cucurbita floral volatiles.

    Science.gov (United States)

    Andrews, Elizabeth S; Theis, Nina; Adler, Lynn S

    2007-09-01

    Mutualists and antagonists may place conflicting selection pressures on plant traits. For example, the evolution of floral traits is typically studied in the context of attracting pollinators, but traits may incur fitness costs if they are also attractive to antagonists. Striped cucumber beetles (Acalymma vittatum) feed on cucurbits and are attracted to several volatiles emitted by Cucurbita blossoms. However, the effect of these volatiles on pollinator attraction is unknown. Our goal was to determine whether pollinators were attracted to the same or different floral volatiles as herbivorous cucumber beetles. We tested three volatiles previously found to attract cucumber beetles in a factorial design to determine attraction of squash bees (Peponapis pruinosa), the specialist pollinators of cucurbita species, as well as the specialist herbivore A. vittatum. We found that 1,2,4-trimethoxybenzene was attractive to both the pollinator and the herbivore, indole was attractive only to the herbivore, and (E)-cinnamaldehyde was attractive only to the pollinator. There were no interactions among volatiles on attraction of squash bees or cucumber beetles. Our results suggest that reduced indole emission could benefit plants by reducing herbivore attraction without loss of pollination, and that 1,2,4-trimethoxybenzene might be under conflicting selection pressure from mutualists and antagonists. By examining the attraction of both mutualists and antagonists to Cucurbita floral volatiles, we have demonstrated the potential for some compounds to influence only one type of interaction, while others may affect both interactions and possibly result in tradeoffs. These results shed light on the potential evolution of fragrance in native Cucurbita, and may have consequences for yield in agricultural settings.

  11. Modulation of plant defense responses to herbivores by simultaneous recognition of different herbivore-associated elicitors in rice.

    Science.gov (United States)

    Shinya, Tomonori; Hojo, Yuko; Desaki, Yoshitake; Christeller, John T; Okada, Kazunori; Shibuya, Naoto; Galis, Ivan

    2016-01-01

    Induced plant defense responses against insect herbivores are triggered by wounding and/or perception of herbivore elicitors from their oral secretions (OS) and/or saliva. In this study, we analyzed OS isolated from two rice chewing herbivores, Mythimna loreyi and Parnara guttata. Both types of crude OS had substantial elicitor activity in rice cell system that allowed rapid detection of early and late defense responses, i.e. accumulation of reactive oxygen species (ROS) and defense secondary metabolites, respectively. While the OS from M. loreyi contained large amounts of previously reported insect elicitors, fatty acid-amino acid conjugates (FACs), the elicitor-active P. guttata's OS contained no detectable FACs. Subsequently, elicitor activity associated with the high molecular mass fraction in OS of both herbivores was identified, and shown to promote ROS and metabolite accumulations in rice cells. Notably, the application of N-linolenoyl-Gln (FAC) alone had only negligible elicitor activity in rice cells; however, the activity of isolated elicitor fraction was substantially promoted by this FAC. Our results reveal that plants integrate various independent signals associated with their insect attackers to modulate their defense responses and reach maximal fitness in nature. PMID:27581373

  12. Herbivore defense responses and associated herbivore defense mechanism as revealed by comparing a resistant wild soybean with a susceptible cultivar

    Directory of Open Access Journals (Sweden)

    Xiaoyi Wang

    2015-12-01

    Full Text Available Plants have evolved sophisticated defense mechanisms against herbivores to help them adapt to the environment. Understanding the defense mechanisms in plants can help us control insects in a more effective manner. In this study, we found that compared with Tianlong 2 (a cultivated soybean with insect susceptibility, ED059 (a wild soybean line with insect resistance contains sharper pubescence tips, as well as lower transcript levels of wound-induced protein kinase (WIPK and salicylic acid-induced protein kinase (SIPK, which are important mitogen-activated protein kinases involved in early defense response to herbivores. The observed lower transcript levels of WIPK and SIPK induced higher levels of jasmonic acid (JA, JA biosynthesis enzymes (AOC3 and some secondary metabolites in ED059. Functional analysis of the KTI1 gene via Agrobacterium-mediated transformation in Arabidopsis thaliana indicated that it plays an important role in herbivore defense in ED059. We further investigated the molecular response of third-instar Helicoverpa armigera (Hübner larvae to Tianlong 2 and ED059. We found apoptotic cells only in the midguts of larvae that fed on ED059. Compared with larvae reared on the susceptible cultivar Tianlong 2, transcript levels of catalase (CAT and glutathione S-transferase (GST were up-regulated, whereas those of CAR, CHSB, and TRY were down-regulated in larvae that fed on the highly resistant variety ED059. We propose that these differences underlie the different herbivore defense responses of ED059 and Tianlong 2.

  13. Quantification of insecticide resistance in the tobacco-adapted form of the green peach aphid, Myzus persicae (Sulzer)(Hemiptera: Aphididae)

    OpenAIRE

    Srigiriraju, Lakshmipathi

    2008-01-01

    The tobacco-adapted form of the green peach aphid, Myzus persicae (Sulzer), is one of the most important insect pests of tobacco in the United States and around the world. Insecticides play a major role in controlling the aphid on tobacco because natural enemies usually fail to maintain its populations below damaging levels. The aphid has a history of developing resistance to many insecticides. Therefore, baseline information on the aphidâ s susceptibility to imidacloprid and other insect...

  14. Shallot aphids, Myzus ascalonicus, in strawberry: biocontrol potential of three predators and three parasitoids.

    Science.gov (United States)

    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 assays, both Aphidius colemani Viereck (Hymenoptera: Aphidiidae) and A. ervi Haliday readily stung shallot aphids, with no significant difference in stinging frequency between the two species. A. ervi induced a significantly higher mortality (79.0 ± 7.2%) in terms of stung aphids compared with A. colemani (55.3 ± 4.1%); however, only a minor fraction (2.7 ± 1.8% and 7.1 ± 3.1%, respectively) of the killed aphids resulted in formation of mummies, presumably due to a physiological response to parasitism. The low percentage of mummification precludes the use of either Aphidius species in anything but inundative biocontrol. In similar set-ups, Aphelinus abdominalis (Dalman) (Hymenoptera: Aphelinidae) killed almost half (49.6 ± 5.3%) of the exposed aphids through host feeding. In addition, 23.2 ± 7.3% of non-host-fed aphids developed into mummified aphids, and 38.1 ± 13.2% of non-host-fed aphids died from 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: Chrysopidae), the two-spotted lady beetle, Adalia bipunctata L. (Coleoptera: Coccinellidae), and the gall midge Aphidoletes aphidimyza (Rondani) (Diptera: Cecidomyiidae). Third instars of all 3 predators readily preyed upon the shallot aphid in Petri dish set-ups with significant differences in daily

  15. Responses of Herbivorous Fishes and Benthos to 6 Years of Protection at the Kahekili Herbivore Fisheries Management Area, Maui.

    Science.gov (United States)

    Williams, Ivor D; White, Darla J; Sparks, Russell T; Lino, Kevin C; Zamzow, Jill P; Kelly, Emily L A; Ramey, Hailey L

    2016-01-01

    In response to concerns about declining coral cover and recurring macroalgal blooms, in 2009 the State of Hawaii established the Kahekili Herbivore Fisheries Management Area (KHFMA). Within the KHFMA, herbivorous fishes and sea urchins are protected, but other fishing is allowed. As part of a multi-agency monitoring effort, we conducted surveys at KHFMA and comparison sites around Maui starting 19 months before closure, and over the six years since implementation of herbivore protection. Mean parrotfish and surgeonfish biomass both increased within the KHFMA (by 139% [95%QR (quantile range): 98-181%] and 28% [95%QR: 3-52%] respectively). Most of those gains were of small-to-medium sized species, whereas large-bodied species have not recovered, likely due to low levels of poaching on what are preferred fishery targets in Hawaii. Nevertheless, coincident with greater biomass of herbivores within the KHFMA, cover of crustose coralline algae (CCA) has increased from ~2% before closure to ~ 15% in 2015, and macroalgal cover has remained low throughout the monitoring period. Strong evidence that changes in the KHFMA were a consequence of herbivore management are that (i) there were no changes in biomass of unprotected fish families within the KHFMA; and that (ii) there were no similar changes in parrotfish or CCA at comparison sites around Maui. It is not yet clear how effective herbivore protection might eventually be for the KHFMA's ultimate goal of coral recovery. Coral cover declined over the first few years of surveys-from 39.6% (SE 1.4%) in 2008, to 32.9% (SE 0.8%) in 2012, with almost all of that loss occurring by 2010 (1 year after closure), i.e. before meaningful herbivore recovery had occurred. Coral cover subsequently stabilized and may have slightly increased from 2012 through early 2015. However, a region-wide bleaching event in 2015 had already led to some coral mortality by the time surveys were conducted in late 2015, at which time cover had dropped back

  16. Responses of Herbivorous Fishes and Benthos to 6 Years of Protection at the Kahekili Herbivore Fisheries Management Area, Maui.

    Directory of Open Access Journals (Sweden)

    Ivor D Williams

    Full Text Available In response to concerns about declining coral cover and recurring macroalgal blooms, in 2009 the State of Hawaii established the Kahekili Herbivore Fisheries Management Area (KHFMA. Within the KHFMA, herbivorous fishes and sea urchins are protected, but other fishing is allowed. As part of a multi-agency monitoring effort, we conducted surveys at KHFMA and comparison sites around Maui starting 19 months before closure, and over the six years since implementation of herbivore protection. Mean parrotfish and surgeonfish biomass both increased within the KHFMA (by 139% [95%QR (quantile range: 98-181%] and 28% [95%QR: 3-52%] respectively. Most of those gains were of small-to-medium sized species, whereas large-bodied species have not recovered, likely due to low levels of poaching on what are preferred fishery targets in Hawaii. Nevertheless, coincident with greater biomass of herbivores within the KHFMA, cover of crustose coralline algae (CCA has increased from ~2% before closure to ~ 15% in 2015, and macroalgal cover has remained low throughout the monitoring period. Strong evidence that changes in the KHFMA were a consequence of herbivore management are that (i there were no changes in biomass of unprotected fish families within the KHFMA; and that (ii there were no similar changes in parrotfish or CCA at comparison sites around Maui. It is not yet clear how effective herbivore protection might eventually be for the KHFMA's ultimate goal of coral recovery. Coral cover declined over the first few years of surveys-from 39.6% (SE 1.4% in 2008, to 32.9% (SE 0.8% in 2012, with almost all of that loss occurring by 2010 (1 year after closure, i.e. before meaningful herbivore recovery had occurred. Coral cover subsequently stabilized and may have slightly increased from 2012 through early 2015. However, a region-wide bleaching event in 2015 had already led to some coral mortality by the time surveys were conducted in late 2015, at which time cover had

  17. Positive interactions between large herbivores and grasshoppers, and their consequences for grassland plant diversity.

    Science.gov (United States)

    Zhong, Zhiwei; Wang, Deli; Zhu, Hui; Wang, Ling; Feng, Chao; Wang, Zhongnan

    2014-04-01

    Although the influence of positive interactions on plant and sessile communities has been well documented, surprisingly little is known about their role in structuring terrestrial animal communities. We evaluated beneficial interactions between two distantly related herbivore taxa, large vertebrate grazers (sheep) and smaller insect grazers (grasshoppers), using a set of field experiments in eastern Eurasian steppe of China. Grazing by large herbivores caused significantly higher grasshopper density, and this pattern persisted until the end of the experiment. Grasshoppers, in turn, increased the foraging time of larger herbivores, but such response occurred only during the peak of growing season (August). These reciprocal interactions were driven by differential herbivore foraging preferences for plant resources; namely, large herbivores preferred Artemisia forbs, whereas grasshoppers preferred Leymus grass. The enhancement of grasshopper density in areas grazed by large herbivores likely resulted from the selective consumption of Artemisia forbs by vertebrate grazers, which may potentially improve the host finding of grasshoppers. Likewise, grasshoppers appeared to benefit large herbivores by decreasing the cover and density of the dominant grass Leymus chinensis, which hampers large herbivores' access to palatable forbs. Moreover, we found that large herbivores grazing alone may significantly decrease plant diversity, yet grasshoppers appeared to mediate such negative effects when they grazed with large herbivores. Our results suggest that the positive, reciprocal interactions in terrestrial herbivore communities may be more prevalent and complex than previously thought.

  18. The ethylene response factor Pti5 contributes to potato aphid resistance in tomato independent of ethylene signalling.

    Science.gov (United States)

    Wu, Chengjun; Avila, Carlos A; Goggin, Fiona L

    2015-02-01

    Ethylene response factors (ERFs) comprise a large family of transcription factors that regulate numerous biological processes including growth, development, and response to environmental stresses. Here, we report that Pti5, an ERF in tomato [Solanum lycopersicum (Linnaeus)] was transcriptionally upregulated in response to the potato aphid Macrosiphum euphorbiae (Thomas), and contributed to plant defences that limited the population growth of this phloem-feeding insect. Virus-induced gene silencing of Pti5 enhanced aphid population growth on tomato, both on an aphid-susceptible cultivar and on a near-isogenic genotype that carried the Mi-1.2 resistance (R) gene. These results indicate that Pti5 contributes to basal resistance in susceptible plants and also can synergize with other R gene-mediated defences to limit aphid survival and reproduction. Although Pti5 contains the ERF motif, induction of this gene by aphids was independent of ethylene, since the ACC deaminase (ACD) transgene, which inhibits ethylene synthesis, did not diminish the responsiveness of Pti5 to aphid infestation. Furthermore, experiments with inhibitors of ethylene synthesis revealed that Pti5 and ethylene have distinctly different roles in plant responses to aphids. Whereas Pti5 contributed to antibiotic plant defences that limited aphid survival and reproduction on both resistant (Mi-1.2+) and susceptible (Mi-1.2-) genotypes, ethylene signalling promoted aphid infestation on susceptible plants but contributed to antixenotic defences that deterred the early stages of aphid host selection on resistant plants. These findings suggest that the antixenotic defences that inhibit aphid settling and the antibiotic defences that depress fecundity and promote mortality are regulated through different signalling pathways. PMID:25504643

  19. The influence of virus-induced changes in plants on aphid vectors: insights from luteovirus pathosystems.

    Science.gov (United States)

    Bosque-Pérez, Nilsa A; Eigenbrode, Sanford D

    2011-08-01

    Plant virus infection can alter the suitability of host plants for their aphid vectors. Most reports indicate that virus-infected plants are superior hosts for vectors compared to virus-free plants with respect to vector growth rates, fecundity and longevity. Some aphid vectors respond preferentially to virus-infected plants compared to virus-free ones, while others avoid infected plants that are inferior hosts. Thus, it appears vectors can exploit changes in host plant quality associated with viral infection. Enhanced vector performance and preference for virus-infected plants might also be advantageous for viruses by promoting their spread and possibly enhancing their fitness. Our research has focused on two of the most important luteoviruses that infect wheat (Barley yellow dwarf virus), or potato (Potato leafroll virus), and their respective aphid vectors, the bird-cherry oat aphid, Rhopalosiphum padi, and the green peach aphid, Myzus persicae. The work has demonstrated that virus infection of host plants enhances the life history of vectors. Additionally, it has shown that virus infection alters the concentration and relative composition of volatile organic compounds in host plants, that apterae of each vector species settle preferentially on virus-infected plants, and that such responses are mediated by volatile organic compounds. The findings also indicate that plants respond heterogeneously to viral infection and as a result different plant parts change in attractiveness to vectors during infection and vector responses to virus-infected plants are dynamic. Such dynamic responses could enhance or reduce the probability of virus acquisition by individual aphids searching among plants. Finally, our work indicates that compared to non-viruliferous aphids, viruliferous ones are less or not responsive to virus-induced host plant volatiles. Changes in vector responsiveness to plants after vectors acquire virus could impact virus epidemiology by influencing virus

  20. Aphid populations (Hemiptera: Aphidoidea depend of mulching in watermelon production in the Mediterranean region of Croatia

    Directory of Open Access Journals (Sweden)

    K. Zanic

    2013-10-01

    Full Text Available Winged morphs of aphids were investigated under field conditions during 2008, 2010 and 2011 in the Mediterranean region of Croatia. Field experiments were conducted to record aphid diversity and compare polyethylene black mulch to straw mulch and bare soil in terms of their attractiveness to aphid species in a watermelon crop. Aphids were collected weekly using yellow water metal traps from May to July. During the study, 44 species in 31 genera were detected; 36 species in 24 genera were identified in 2008, 18 species in 15 genera were identified in 2010, and 34 species in 25 genera were identified in 2011. The overall seasonal percentage composition showed that Aphis fabae Scopoli and Myzus persicae (Sulzer were consistently eudominant species, whereas Acyrtosiphon pisum (Harris was consistently dominant. Cabbage aphid Brevicoryne brassicae (L. was determined as the dominant species in 2008 and as eudominant species in 2011. Additionally, Macrosiphum rosae (L. was twice recorded as the dominant species, whereas Aphis gossipii Glover was dominant once, and Phorodon humuli (Schrank was eudominant once. Our study also demonstrated that mulching sporadically affected the abundance of individual species. The attractiveness of mulching for aphid species differed between the treatments. It was found that bare soil was attractive to A. pisum and M. rosae, black mulch was attractive to B. helichrysi and P. humuli, and straw mulch was attractive to four aphid species, of which two were eudominant, A. fabae and M. persicae. The presented species are mostly polyphagous, and their preference for certain mulches can be used in crop protection management.

  1. 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.

  2. The physiology of sterol nutrition in the pea aphid Acyrthosiphon pisum.

    Science.gov (United States)

    Bouvaine, Sophie; T Behmer, Spencer; Lin, George G; Faure, Marie-Line; Grebenok, Robert J; Douglas, Angela E

    2012-11-01

    The phloem sap of fava bean (Vicia faba) plants utilized by the pea aphid Acyrthosiphon pisum contains three sterols, cholesterol, stigmasterol and sitosterol, in a 2:2:1 ratio. To investigate the nutritional value of these sterols, pea aphids were reared on chemically-defined diets containing each sterol at 0.1, 1 and 10μgml(-1) with a sterol-free diet as control. Larval growth rate and aphid lifespan did not vary significantly across the diets, indicating that sterol reserves can buffer some performance indices against a shortfall in dietary sterol over at least one generation. However, lifetime reproductive output was depressed in aphids on diets containing stigmasterol or no sterol, relative to diets supplemented with cholesterol or sitosterol. The cholesterol density of embryos in teneral adults was significantly higher than in the total body; and the number and biomass of embryos in aphids on diets with stigmasterol and no sterols were reduced relative to diets with cholesterol or sitosterol, indicating that the reproductive output of the pea aphid can be limited by the amount and composition of dietary sterol. In a complementary RNA-seq analysis of pea aphids reared on plants and diets with different sterol contents, 7.6% of the 17,417 detected gene transcripts were differentially expressed. Transcript abundance of genes with annotated function in sterol utilization did not vary significantly among treatments, suggesting that the metabolic response to dietary sterol may be mediated primarily at the level of enzyme function or metabolite concentration. PMID:22878342

  3. [Obtainment of transgenic wheat with the insecticidal lectin from snowdrop (Galanthus nivalis agglutinin; GNA) gene and analysis of resistance to aphid].

    Science.gov (United States)

    Liang, Hui; Zhu, Yin-Feng; Zhu, Zhen; Sun, Dong-Fa; Jia, Xu

    2004-02-01

    Snowdrop lectin (Galanthus nivalis agglutinin; GNA) is toxic to sap sucking injurious insects of Homopteran. A new gna gene has been transferred into common spring wheat Zhong60634 and winter wheat Yumai66 with high yield by using the biolistic transformation method. Transgenic wheat plants have been obtained in both of the two varieties. Two transgenic plants (T0) have been obtained from the bombarded 535 immature embryos of Zhong60634. Bioassay results show that the development of aphid could be slowed down and the survival rate of young aphid could be reduced by gna gene. Seventeen transgenic plants (T0) were obtained from the bombarded 4636 immature embryos of Yumai66. Twenty plantlets with good resistance to Rhopalosiphum padi and Macrosiphum avenae, which are mainly aphid in north wheat area, were identified from the transgenic plants of T1 generation that came from 8 T0 transgenic plants with good resistance to aphid. The anti-aphid bioassay shows that resistance to the different grain aphid is not the same in transgenic wheat plants. To Rhopalosiphum padi, the rate of survival aphid 8 days after exposing transgenic plants to aphids is significantly lower than that of nontransgenic plants. To Macrosiphum avenae, growth speed of aphids is slowed down but not killed. At the same time, the death rate of young aphids is increased. Anyway, feeding of the two kinds of aphids has been controlled in a certain degree by gna gene when aphids can free to move in plants.

  4. Reflex sympathetic dystrophy: the significance of differing plasma catecholamine concentrations in affected and unaffected limbs.

    Science.gov (United States)

    Drummond, P D; Finch, P M; Smythe, G A

    1991-10-01

    In 26 patients with features of reflex sympathetic dystrophy, venous blood was collected from painful and unaffected limbs. Levels of plasma adrenaline, noradrenaline and its intracellular metabolite, 3,4-dihydroxyphenylethyleneglycol (DHPG), were measured by combined gas chromatography/mass spectrometry. Plasma DHPG was lower on the painful side. Concentration of plasma noradrenaline was also lower on the painful side in patients with widespread allodynia, and in those with hyperhidrosis in the affected hand or foot. These findings do not support the widely held view that autonomic disturbances in reflex sympathetic dystrophy are due to sympathetic overactivity. Rather, they suggest that sweating and changes in peripheral blood flow result from supersensitivity to sympathetic neurotransmitters. After injury, supersensitivity to noradrenaline may also contribute to spontaneous pain and allodynia by disrupting efferent sympathetic modulation of sensation. This would explain why pain and allodynia are relieved by sympathetic blockade, and why noradrenaline rekindles pain in sympathectomized skin. PMID:1933231

  5. Weed host specificity of the aphid, Aphis spiraecola: developmental and reproductive performance of aphids in relation to plant growth and leaf chemicals of the Siam weed, Chromolaena odorata.

    Science.gov (United States)

    Agarwala, B K; Das, Jhuma

    2012-01-01

    Density, distribution, and nutritional quality of plants are the causal basis of host plant selection in aphids. Nutritional qualities of a plant vary according to its growth stage and also in response to seasonal variation. How host plant growth stages shape aphid performance was studied in Aphis spiraecola Patch (Homoptera: Aphididae) on the perennial Siam weed, Chromolaena odorata (L.) King and Robinson (Asterales: Asteraceae). This plant species is the preferred host in the hot and humid tropical parts of northeast and southern India. Variations in developmental and reproductive performances in apterous viviparous female aphids were recorded in relation to differences in leaf chemicals in different growth stages of C. odorata. Aphids reproduced at higher rates in the vegetative stage of C. odorata when developmental time was shortest, and fecundity was higher in a longer reproductive time. Intrinsic rate of increase and net reproductive rate were also recorded to be higher in the vegetative stage of the weed host. In the vegetative stage, leaves contained higher quantity of proteins and nitrogen, which are vital for insect reproduction. Results of this study have demonstrated that A spiraecola showed synchronization of its developmental and reproductive performances to growth stages of C. odorata, which occur in high abundance in the study area. PMID:22950746

  6. Potential exposure of a classical biological control agent of the soybean aphid, Aphis glycines, on non-target aphids in North America

    Science.gov (United States)

    In summer 2007, the Asian parasitoid Binodoxys communis (Hymenoptera: Braconidae) was released in North America for control of the exotic soybean aphid, Aphis glycines (Homoptera: Aphididae). Despite its comparatively narrow host range, releases of B. communis may still constitute a risk to native a...

  7. Spondyloepiphseal dysplasia congenita in siblings born to unaffected parents: ? germ line mosaicism

    Energy Technology Data Exchange (ETDEWEB)

    Mulla, W.; McDonald-McGinn, D.; Zackai, E. [Univ. of Pennsylvania School of Medicine, Philadelphia, PA (United States)] [and others

    1994-09-01

    Germ line mosaicism has been used to explain the birth of more than one child affected with a dominantly inherited disorder born to unaffected parents. Furthermore, it has been confirmed clinically in families where recurrence in siblings was originally thought to be autosomal recessive, but were affected individuals have reproduced affected offspring. Firm evidence of germ line mosaicism using mutation analysis by molecular methods exists for some autosomal disorders. We present two siblings with spondyloepipheseal dysplasia congenita (SEDC) born to unaffected parents. This suggests the presence of germ line mosaicism in this entity. Patient 1 was born at 32 weeks gestation to a G1P1 Puerto Rican mother. The pregnancy was complicated by polyhydramnios. The neonate, a short-limbed dwarf, died at 15 hours of age from respiratory distress and a compromised thoracic cavity. Patient 2, the sibling of patient 1 was born at 37 weeks gestation after a pregnancy complicated by polyhydramnios and prenatal ultrasound diagnosis of short-limbed dwarfism. The diagnosis of SEDC was made and, after review of the sibling`s postmortem X-rays, it was felt that she was similarly affected. The family history reveals no history of dwarfism or consanguinity. The SEDC is described as an autosomal dominant form of dwarfism with variable presentation including some cases that have been lethal in the neonatal period. SEDC is now believed to represent a family of collagen II mutations. Sporadic cases that have arisen in families with no history have been ascribed to new heterozygous mutations. Other families in which SEDC and SEMD recurred without a family history most likely represent germ line mosaicism. In these cases molecular studies should be pursued to document a collagen II mutation. We believe that germ line mosaicism is the most plausible explanation for recurrence in our family.

  8. Serotonergic antidepressants decrease hedonic signals but leave learning signals in the nucleus accumbens unaffected.

    Science.gov (United States)

    Graf, Heiko; Metzger, Coraline D; Walter, Martin; Abler, Birgit

    2016-01-01

    Investigating the effects of serotonergic antidepressants on neural correlates of visual erotic stimulation revealed decreased reactivity within the dopaminergic reward network along with decreased subjective sexual functioning compared with placebo. However, a global dampening of the reward system under serotonergic drugs is not intuitive considering clinical observations of their beneficial effects in the treatment of depression. Particularly, learning signals as coded in prediction error processing within the dopaminergic reward system can be assumed to be rather enhanced as antidepressant drugs have been demonstrated to facilitate the efficacy of psychotherapeutic interventions relying on learning processes. Within the same study sample, we now explored the effects of serotonergic and dopaminergic/noradrenergic antidepressants on prediction error signals compared with placebo by functional MRI. A total of 17 healthy male participants (mean age: 25.4 years) were investigated under the administration of paroxetine, bupropion and placebo for 7 days each within a randomized, double-blind, within-subject cross-over design. During functional MRI, we used an established monetary incentive task to explore neural prediction error signals within the bilateral nucleus accumbens as region of interest within the dopaminergic reward system. In contrast to diminished neural activations and subjective sexual functioning under the serotonergic agent paroxetine under visual erotic stimulation, we revealed unaffected or even enhanced neural prediction error processing within the nucleus accumbens under this antidepressant along with unaffected behavioural processing. Our study provides evidence that serotonergic antidepressants facilitate prediction error signalling and may support suggestions of beneficial effects of these agents on reinforced learning as an essential element in behavioural psychotherapy. PMID:26555033

  9. Population fluctuation and faunal indices of aphids (Hemiptera, Aphididae) in peach orchards in Araucária, PR.

    Science.gov (United States)

    Schuber, J M; Monteiro, L B; Poltronieri, A S; Carvalho, R C Z; Zawadneak, M A C

    2009-08-01

    Aphids are sap-sucking insects that mainly attack shoots and young leaves of peach trees and many other plant species; however, knowledge of the Brazilian aphid fauna is scant. The objective of this study was to identify aphid species collected in peach orchards (Prunus persica Batsch) and to determine their faunal indices for occurrence and dominance. The experiment was conducted from July 2005 to September 2006 in six Chimarrita peach orchards in the municipality of Araucária, PR, Brazil. The survey of aphid species was conducted by visual samplings on peach trees and using Möericke-type yellow traps containing water. A faunal analysis was made using aphid occurrence and dominance indices. Brachycaudus persicae (Passerini, 1860) was the only aphid species that was found colonizing peach in Araucária/PR. Although most aphids collected were classified as rare, some can be considered potential peach colonizers, such as Myzus persicae (Sulzer, 1776) which was given the status of common or intermediate in some of the orchards studied. The population fluctuation of aphids showed a negative correlation with rainfall and positive correlation with temperature and relative humidity. PMID:19802456

  10. Biological control of cotton aphid (Aphis gossypii Glover) in cotton (inter)cropping systems in China; a simulation study.

    NARCIS (Netherlands)

    Xia, J.

    1997-01-01

    Cotton aphid ( Aphis gossypii Glover) is the key insect pest of seedling cotton ( Gossypium hirsutum L. ) in China, particularly in the North China cotton region. The resulting annual losses amount to 10-15% of the attainable yield. Sole reliance on insecticides against the cotton aphid in the past

  11. Using multispectral imagery to compare the spatial pattern of injury to wheat caused by Russian wheat aphid and greenbug

    Science.gov (United States)

    The Russian wheat aphid, Diuraphis noxia (Mordvilko), and greenbug, Schizaphis graminum (Rondani), are important aphid pests of wheat. Outbreaks of both pests in commercial wheat fields occur almost every year in the Great Plains of the United States. Infestations of both pests in wheat fields are...

  12. Peripheral odour perception by adult aphid forms with the same genotype but different host-plant preferences

    NARCIS (Netherlands)

    Hardie, J.; Visser, J.H.; Piron, P.G.M.

    1995-01-01

    As adults, the summer (alate virginopara) and autumn (gynopara) winged forms of the black bean aphid, Aphis fabae, utilise different host plants, the bean Vicia faba, and the spindle tree, Euonymus europaeus, respectively. Electroantennograms (EAGs) were recorded from the antennae of these aphid for

  13. Coupling genetics and proteomics to identify aphid proteins associated with vector-specific transmission of Polerovirus (Luteoviridae)

    Science.gov (United States)

    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 endocyto...

  14. Land-use history alters contemporary insect herbivore community composition and decouples plant-herbivore relationships.

    Energy Technology Data Exchange (ETDEWEB)

    Hahn, Philip G. [University of Wisconsin; Orrock, John L. [University of Wisconsin

    2015-04-01

    1. Past land use can create altered soil conditions and plant communities that persist for decades, although the effects of these altered conditions on consumers are rarely investigated. 2. Using a large-scale field study at 36 sites in longleaf pine (Pinus palustris) woodlands, we examined whether historic agricultural land use leads to differences in the abundance and community composition of insect herbivores (grasshoppers, families Acrididae and Tettigoniidae). 3. We measured the cover of six plant functional groups and several environmental variables to determine whether historic agricultural land use affects the relationships between plant cover or environmental conditions and grasshopper assemblages. 4. Land-use history had taxa-specific effects and interacted with herbaceous plant cover to alter grasshopper abundances, leading to significant changes in community composition. Abundance of most grasshopper taxa increased with herbaceous cover in woodlands with no history of agriculture, but there was no relationship in post-agricultural woodlands. We also found that grasshopper abundance was negatively correlated with leaf litter cover. Soil hardness was greater in post-agricultural sites (i.e. more compacted) and was associated with grasshopper community composition. Both herbaceous cover and leaf litter cover are influenced by fire frequency, suggesting a potential indirect role of fire on grasshopper assemblages. 5. Our results demonstrate that historic land use may create persistent differences in the composition of grasshopper assemblages, while contemporary disturbances (e.g. prescribed fire) may be important for determining the abundance of grasshoppers, largely through the effect of fire on plants and leaf litter. Therefore, our results suggest that changes in the contemporary management regimes (e.g. increasing prescribed fire) may not be sufficient to shift the structure of grasshopper communities in post-agricultural sites towards communities in

  15. Aphid salivary proteases are capable of degrading sieve-tube proteins.

    Science.gov (United States)

    Furch, Alexandra C U; van Bel, Aart J E; Will, Torsten

    2015-02-01

    Sieve tubes serve as transport conduits for photo-assimilates and other resources in angiosperms and are profitable targets for piercing-sucking insects such as aphids. Sieve-tube sap also contains significant amounts of proteins with diverse functions, for example in signalling, metabolism, and defence. The identification of salivary proteases in Acyrthosiphon pisum led to the hypothesis that aphids might be able to digest these proteins and by doing so suppress plant defence and access additional nitrogen sources. Here, the scarce knowledge of proteases in aphid saliva is briefly reviewed. In order to provide a better platform for discussion, we conducted a few tests on in vitro protease activity and degradation of sieve-tube sap proteins of Cucurbita maxima by watery saliva. Inhibition of protein degradation by EDTA indicates the presence of different types of proteases (e.g. metalloproteses) in saliva of A. pisum. Proteases in the watery saliva from Macrosiphum euphorbiae and A. pisum were able to degrade the most abundant phloem protein, which is phloem protein 1. Our results provide support for the breakdown of sieve-element proteins by aphid saliva in order to suppress/neutralize the defence responses of the plant and to make proteins of sieve-tube sap accessible as a nitrogen source, as is discussed in detail. Finally, we discuss whether glycosylation of sieve-element proteins and the presence of protease inhibitors may confer partial protection against the proteolytic activity of aphid saliva. PMID:25540441

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

    Directory of Open Access Journals (Sweden)

    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.

  17. Distribution, host plants and natural enemies of sugar beet root aphid (Pemphigus fuscicornis In Slovakia

    Directory of Open Access Journals (Sweden)

    Tóth Peter

    2006-01-01

    Full Text Available During 2003-2004, field surveys were realized to observe the distribution of sugar beet aphid, Pemphigus fuscicornis (K o c h (Sternorrhyncha Pemphigidae in southwestern Slovakia. The research was carried out at 60 different localities with altitudes 112-220 m a. s. l. Sugar beet root aphid was recorded at 30 localities. The aphid was recorded in Slovakia for the first time, but its occurrence was predicted and symptoms and harmfulness overlooked by now. The presence of P. fuscicornis was investigated on roots of various plants from Chenopodiaceae. The most important host plants were various species of lambsquarters (above all Chenopodium album. Furthermore sugar beet (Beta vulgaris provar. altissima, red beet (B. vulgaris provar. conditiva and oraches (Atriplex spp act as host plants. Infestation of sugar beet by P. fuscicornis never exceeded 5% at single locality in Slovakia. Dry and warm weather create presumptions for strong harmfulness. In Slovakia, Chenopodium album is a very important indicator of sugar beet aphid presence allowing evaluation of control requirements. During the study, the larvae of Thaumatomyia glabra (Diptera: Chloropidae were detected as important natural enemies of sugar beet aphid. The species occurred at each location evaluated.

  18. Returns to integrated pest management research and outreach for soybean aphid.

    Science.gov (United States)

    Song, Feng; Swinton, Scott M

    2009-12-01

    Soybean aphid, Aphis glycines Matsumura, is a major invasive pest that has caused substantial yield loss and increased insecticide use in the United States since its discovery in 2000. Using the economic surplus approach, we estimate the economic benefits of U.S. research and outreach for integrated pest management (IPM) of soybean aphid. We calculate ex ante net benefits from adoption of an IPM economic threshold (ET). The ET triggers insecticide application only if the value of predicted yield damage from pest scouting is expected to exceed the cost of pest control. Our research finds that gradual adoption of an ET for soybean aphid management will generate a projected economic net benefit of $1.3 billion, for an internal rate of return of 124%, over the 15 yr since soybean aphid IPM research began in 2003. Lower and upper bound sensitivity analysis brackets the estimated net benefit to U.S. consumers and soybean, Glycine max (L.) Merr., growers in the range of $0.6 to $2.6 billion in 2005 dollars. If a 10% rate of return is attributed to IPM applied research and outreach on soybean aphid, that would leave nearly $800 million to compensate prior activities that contribute to the development and adoption of IPM.

  19. Annotated expressed sequence tags and xenobiotic detoxification in the aphid Myzus persicae (Sulzer)

    Institute of Scientific and Technical Information of China (English)

    C.C. FIGUEROA; N. PRUNIER-LETERME; C. RISPE; F. SEPULVEDA; E. FUENTES-CONTRERAS; B. SABATER-MUNOZ; J.-C. SIMON; D. TAGU

    2007-01-01

    Aphids (Hemiptera: Aphididae) are phytophagous insects that are importantagricultural pests. The enormous negative economic impacts caused by aphids worldwide arewell known, and are mostly due to their high multiplication rate and the transmission ofphytopathogenic viruses. Aphid management strategies mainly involve chemical treatmentswhich are pollutants and are increasingly inefficient, since aphids have developed multipleinsecticide-resistant mechanisms. Among the most economically important species is thegreen peach aphid Myzuspersicae Sulzer (Aphididae: Macrosiphini), which is able to colonizea wide range of host plants belonging to many different families, and transmits numerous plantviruses. Because of its large prevalence, M. persicae has been the target of massive insecticidetreatments; consequently, it has evolved several insecticide-resistant mechanisms. In thiswork, a collection of expressed genes from M. persicae is presented in order to identify putativegenes involved in xenobiotic detoxification. After cDNA cloning and sequencing, 959expressed sequence tags (EST) were annotated. Most sequences matched known genescorresponded to metabolism proteins (26%), ribosomal proteins (23%) and structural proteins(8%). Among them, several sequences corresponded to proteins putatively involved in sensing,degradation or detoxification of plant xenobiotic products.

  20. 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.

  1. New insight into the RNA interference response against cathepsin-L gene in the pea aphid, Acyrthosiphon pisum

    DEFF Research Database (Denmark)

    Sapountzis, Panagiotis; Duport, Gabrielle; Balmand, Séverine;

    2014-01-01

    RNA interference (RNAi) has been widely and successfully used for gene inactivation in insects, including aphids, where dsRNA administration can be performed either by feeding or microinjection. However, several aspects related to the aphid response to RNAi, as well as the influence......-L gene in the pea aphid, Acyrthosiphon pisum. In order to maximize the possibility of discovering specific phenotypes, the effect of the treatment was analyzed in single individual aphids at the level of five body compartments: the bacteriocytes, the gut, the embryonic chains, the head and the remaining...... body carcass. Our analysis revealed that gene expression knockdown effect in each single body compartment was dependent on the administration method used, and allowed us to discover new functions for the cathepsin-L gene in aphids. Injection of cathepsin-L dsRNA was much more effective on carcass...

  2. 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...

  3. A simple wax-embedding method for isolation of aphid hemolymph for detection of luteoviruses in the hemocoel.

    Science.gov (United States)

    Liu, Sijun; Bonning, Bryony C; Allen Miller, W

    2006-03-01

    A protocol for isolating hemolymph from viruliferous aphids has been developed. This method uses warm melted wax to immobilize the aphid. Following removal of a hind leg, the hemolymph can be collected readily. Flushing with RNase-free water allows for collection of sufficient hemolymph for RNA extraction from individual aphids. The extracted RNA was successfully used for detection of barley yellow dwarf virus (BYDV) and pea enation mosaic virus (PEMV) from individual viruliferous Rhopalosiphum padi and Acyrthosiphon pisum aphids, respectively. A TaqMan real-time RT-PCR protocol for quantitation of PEMV in the hemolymph of individual aphids was developed. The wax-embedding hemolymph collection technique provides a useful tool for studying molecular interactions between persistent and circulative plant viruses and their insect vectors. PMID:16307802

  4. Combined effects of arthropod herbivores and phytopathogens on plant performance

    DEFF Research Database (Denmark)

    Hauser, Thure Pavlo; Christensen, Stina; Heimes, Christine;

    2013-01-01

    1. Many plants are simultaneously attacked by arthropod herbivores and phytopathogens. These may affect each other directly and indirectly, enhancing or reducing the amount of plant resources they each consume. Ultimately, this may reduce or enhance plant performance relative to what should be ex....... However, as interactive impacts also differed among environments and parasite manipulation methods, this suggests that the ability of plants to compensate such losses may depend on environmental conditions and probably also overall infection load......., the patterns we found were related to plant traits and experimental conditions. 5. Our results suggest that immediate loss of resources from interactions between arthropod herbivores and pathogens is generally moderated by compensation to an extent where there are no interactive effects on plant performance...

  5. Associations among coral reef macroalgae influence feeding by herbivorous fishes

    Science.gov (United States)

    Loffler, Z.; Bellwood, D. R.; Hoey, A. S.

    2015-03-01

    Benthic macroalgae often occur in close association with other macroalgae, yet the implications of such associations on coral reefs are unclear. We selected three pairs of commonly associated macroalgae on inshore reefs of the Great Barrier Reef and exposed them, either independently or paired, to herbivore assemblages. Pairing the palatable alga Acanthophora with the calcified and chemically defended Galaxaura resulted in a 69 % reduction in the consumption of Acanthophora, but had no effect on the consumption of Galaxaura. The reduced consumption of Acanthophora was related to 53-85 % reductions in the feeding rates of two herbivorous fish species, Kyphosus vaigiensis and Siganus doliatus. Neither Acanthophora nor Sargassum were afforded protection when paired with the brown macroalga Turbinaria. Although limited to one of the three species pairings, such associations between algae may allow the ecological persistence of palatable species in the face of intense herbivory, enhancing macroalgal diversity on coral reefs.

  6. Community-Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance.

    Directory of Open Access Journals (Sweden)

    Ilja Sonnemann

    Full Text Available Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae larvae (43% in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive- and vegetative plant height, and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio. Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of

  7. Community-Weighted Mean Plant Traits Predict Small Scale Distribution of Insect Root Herbivore Abundance.

    Science.gov (United States)

    Sonnemann, Ilja; Pfestorf, Hans; Jeltsch, Florian; Wurst, Susanne

    2015-01-01

    Small scale distribution of insect root herbivores may promote plant species diversity by creating patches of different herbivore pressure. However, determinants of small scale distribution of insect root herbivores, and impact of land use intensity on their small scale distribution are largely unknown. We sampled insect root herbivores and measured vegetation parameters and soil water content along transects in grasslands of different management intensity in three regions in Germany. We calculated community-weighted mean plant traits to test whether the functional plant community composition determines the small scale distribution of insect root herbivores. To analyze spatial patterns in plant species and trait composition and insect root herbivore abundance we computed Mantel correlograms. Insect root herbivores mainly comprised click beetle (Coleoptera, Elateridae) larvae (43%) in the investigated grasslands. Total insect root herbivore numbers were positively related to community-weighted mean traits indicating high plant growth rates and biomass (specific leaf area, reproductive- and vegetative plant height), and negatively related to plant traits indicating poor tissue quality (leaf C/N ratio). Generalist Elaterid larvae, when analyzed independently, were also positively related to high plant growth rates and furthermore to root dry mass, but were not related to tissue quality. Insect root herbivore numbers were not related to plant cover, plant species richness and soil water content. Plant species composition and to a lesser extent plant trait composition displayed spatial autocorrelation, which was not influenced by land use intensity. Insect root herbivore abundance was not spatially autocorrelated. We conclude that in semi-natural grasslands with a high share of generalist insect root herbivores, insect root herbivores affiliate with large, fast growing plants, presumably because of availability of high quantities of food. Affiliation of insect root

  8. Contrasting effects of different mammalian herbivores on sagebrush plant communities.

    Science.gov (United States)

    Veblen, Kari E; Nehring, Kyle C; McGlone, Christopher M; Ritchie, Mark E

    2015-01-01

    Herbivory by both grazing and browsing ungulates shapes the structure and functioning of terrestrial ecosystems worldwide, and both types of herbivory have been implicated in major ecosystem state changes. Despite the ecological consequences of differences in diets and feeding habits among herbivores, studies that experimentally distinguish effects of grazing from spatially co-occurring, but temporally segregated browsing are extremely rare. Here we use a set of long-term exclosures in northern Utah, USA, to determine how domestic grazers vs. wild ungulate herbivores (including browsers and mixed feeders) affect sagebrush-dominated plant communities that historically covered ~62 million ha in North America. We sampled plant community properties and found that after 22 years grazing and browsing elicited perceptible changes in overall plant community composition and distinct responses by individual plant species. In the woody layer of the plant community, release from winter and spring wild ungulate herbivory increased densities of larger Wyoming big sagebrush (Artemisia tridentata, ssp. wyomingensis) at the expense of small sagebrush, while disturbance associated with either cattle or wild ungulate activity alone was sufficient to increase bare ground and reduce cover of biological soil crusts. The perennial bunchgrass, bottlebrush squirretail (Elymus elymoides), responded positively to release from summer cattle grazing, and in turn appeared to competitively suppress another more grazing tolerant perennial grass, Sandberg's blue grass (Poa secunda). Grazing by domestic cattle also was associated with increased non-native species biomass. Together, these results illustrate that ungulate herbivory has not caused sagebrush plant communities to undergo dramatic state shifts; however clear, herbivore-driven shifts are evident. In a dry, perennial-dominated system where plant community changes can occur very slowly, our results provide insights into potential long

  9. Aquatic herbivores facilitate the emission of methane from wetlands

    OpenAIRE

    Dingemans, B.J.J.; Bakker, E.S.; Bodelier, P.L.E.

    2011-01-01

    Wetlands are significant sources of atmospheric methane. Methane produced by microbes enters roots and escapes to the atmosphere through the shoots of emergent wetland plants. Herbivorous birds graze on helophytes, but their effect on methane emission remains unknown. We hypothesized that grazing on shoots of wetland plants can modulate methane emission from wetlands. Diffusive methane emission was monitored inside and outside bird exclosures, using static flux chambers placed over whole vege...

  10. Migratory herbivorous waterfowl track satellite-derived green wave index.

    Directory of Open Access Journals (Sweden)

    Mitra Shariatinajafabadi

    Full Text Available Many migrating herbivores rely on plant biomass to fuel their life cycles and have adapted to following changes in plant quality through time. The green wave hypothesis predicts that herbivorous waterfowl will follow the wave of food availability and quality during their spring migration. However, testing this hypothesis is hampered by the large geographical range these birds cover. The satellite-derived normalized difference vegetation index (NDVI time series is an ideal proxy indicator for the development of plant biomass and quality across a broad spatial area. A derived index, the green wave index (GWI, has been successfully used to link altitudinal and latitudinal migration of mammals to spatio-temporal variations in food quality and quantity. To date, this index has not been used to test the green wave hypothesis for individual avian herbivores. Here, we use the satellite-derived GWI to examine the green wave hypothesis with respect to GPS-tracked individual barnacle geese from three flyway populations (Russian n = 12, Svalbard n = 8, and Greenland n = 7. Data were collected over three years (2008-2010. Our results showed that the Russian and Svalbard barnacle geese followed the middle stage of the green wave (GWI 40-60%, while the Greenland geese followed an earlier stage (GWI 20-40%. Despite these differences among geese populations, the phase of vegetation greenness encountered by the GPS-tracked geese was close to the 50% GWI (i.e. the assumed date of peak nitrogen concentration, thereby implying that barnacle geese track high quality food during their spring migration. To our knowledge, this is the first time that the migration of individual avian herbivores has been successfully studied with respect to vegetation phenology using the satellite-derived GWI. Our results offer further support for the green wave hypothesis applying to long-distance migrants on a larger scale.

  11. How generalist herbivores exploit belowground plant diversity in temperate grasslands.

    Science.gov (United States)

    Wallinger, Corinna; Staudacher, Karin; Schallhart, Nikolaus; Mitterrutzner, Evi; Steiner, Eva-Maria; Juen, Anita; Traugott, Michael

    2014-08-01

    Belowground herbivores impact plant performance, thereby inducing changes in plant community composition, which potentially leads to cascading effects onto higher trophic levels and ecosystem processes and productivity. Among soil-living insects, external root-chewing generalist herbivores have the strongest impact on plants. However, the lack of knowledge on their feeding behaviour under field conditions considerably hampers achieving a comprehensive understanding of how they affect plant communities. Here, we address this gap of knowledge by investigating the feeding behaviour of Agriotes click beetle larvae, which are common generalist external root-chewers in temperate grassland soils. Utilizing diagnostic multiplex PCR to assess the larval diet, we examined the seasonal patterns in feeding activity, putative preferences for specific plant taxa, and whether species identity and larval instar affect food choices of the herbivores. Contrary to our hypothesis, most of the larvae were feeding-active throughout the entire vegetation period, indicating that the grassland plants are subjected to constant belowground feeding pressure. Feeding was selective, with members of Plantaginaceae and Asteraceae being preferred; Apiaceae were avoided. Poaceae, although assumed to be most preferred, had an intermediate position. The food preferences exhibited seasonal changes, indicating a fluctuation in plant traits important for wireworm feeding choice. Species- and instar-specific differences in dietary choice of the Agriotes larvae were small, suggesting that species and larval instars occupy the same trophic niche. According to the current findings, the food choice of these larvae is primarily driven by plant identity, exhibiting seasonal changes. This needs to be considered when analysing soil herbivore-plant interactions. PMID:24188592

  12. Contrasting effects of different mammalian herbivores on sagebrush plant communities.

    Directory of Open Access Journals (Sweden)

    Kari E Veblen

    Full Text Available Herbivory by both grazing and browsing ungulates shapes the structure and functioning of terrestrial ecosystems worldwide, and both types of herbivory have been implicated in major ecosystem state changes. Despite the ecological consequences of differences in diets and feeding habits among herbivores, studies that experimentally distinguish effects of grazing from spatially co-occurring, but temporally segregated browsing are extremely rare. Here we use a set of long-term exclosures in northern Utah, USA, to determine how domestic grazers vs. wild ungulate herbivores (including browsers and mixed feeders affect sagebrush-dominated plant communities that historically covered ~62 million ha in North America. We sampled plant community properties and found that after 22 years grazing and browsing elicited perceptible changes in overall plant community composition and distinct responses by individual plant species. In the woody layer of the plant community, release from winter and spring wild ungulate herbivory increased densities of larger Wyoming big sagebrush (Artemisia tridentata, ssp. wyomingensis at the expense of small sagebrush, while disturbance associated with either cattle or wild ungulate activity alone was sufficient to increase bare ground and reduce cover of biological soil crusts. The perennial bunchgrass, bottlebrush squirretail (Elymus elymoides, responded positively to release from summer cattle grazing, and in turn appeared to competitively suppress another more grazing tolerant perennial grass, Sandberg's blue grass (Poa secunda. Grazing by domestic cattle also was associated with increased non-native species biomass. Together, these results illustrate that ungulate herbivory has not caused sagebrush plant communities to undergo dramatic state shifts; however clear, herbivore-driven shifts are evident. In a dry, perennial-dominated system where plant community changes can occur very slowly, our results provide insights into

  13. Chemically rich seaweeds poison corals when not controlled by herbivores

    OpenAIRE

    Rasher, Douglas B; Hay, Mark E.

    2010-01-01

    Coral reefs are in dramatic global decline, with seaweeds commonly replacing corals. It is unclear, however, whether seaweeds harm corals directly or colonize opportunistically following their decline and then suppress coral recruitment. In the Caribbean and tropical Pacific, we show that, when protected from herbivores, ~40 to 70% of common seaweeds cause bleaching and death of coral tissue when in direct contact. For seaweeds that harmed coral tissues, their lipid-soluble extracts also prod...

  14. A Latex Metabolite Benefits Plant Fitness under Root Herbivore Attack.

    Directory of Open Access Journals (Sweden)

    Meret Huber

    2016-01-01

    Full Text Available Plants produce large amounts of secondary metabolites in their shoots and roots and store them in specialized secretory structures. Although secondary metabolites and their secretory structures are commonly assumed to have a defensive function, evidence that they benefit plant fitness under herbivore attack is scarce, especially below ground. Here, we tested whether latex secondary metabolites produced by the common dandelion (Taraxacum officinale agg. decrease the performance of its major native insect root herbivore, the larvae of the common cockchafer (Melolontha melolontha, and benefit plant vegetative and reproductive fitness under M. melolontha attack. Across 17 T. officinale genotypes screened by gas and liquid chromatography, latex concentrations of the sesquiterpene lactone taraxinic acid β-D-glucopyranosyl ester (TA-G were negatively associated with M. melolontha larval growth. Adding purified TA-G to artificial diet at ecologically relevant concentrations reduced larval feeding. Silencing the germacrene A synthase ToGAS1, an enzyme that was identified to catalyze the first committed step of TA-G biosynthesis, resulted in a 90% reduction of TA-G levels and a pronounced increase in M. melolontha feeding. Transgenic, TA-G-deficient lines were preferred by M. melolontha and suffered three times more root biomass reduction than control lines. In a common garden experiment involving over 2,000 T. officinale individuals belonging to 17 different genotypes, high TA-G concentrations were associated with the maintenance of high vegetative and reproductive fitness under M. melolontha attack. Taken together, our study demonstrates that a latex secondary metabolite benefits plants under herbivore attack, a result that provides a mechanistic framework for root herbivore driven natural selection and evolution of plant defenses below ground.

  15. Contrasting Effects of Different Mammalian Herbivores on Sagebrush Plant Communities

    OpenAIRE

    Kari E Veblen; Nehring, Kyle C.; McGlone, Christopher M.; Ritchie, Mark E.

    2015-01-01

    Herbivory by both grazing and browsing ungulates shapes the structure and functioning of terrestrial ecosystems worldwide, and both types of herbivory have been implicated in major ecosystem state changes. Despite the ecological consequences of differences in diets and feeding habits among herbivores, studies that experimentally distinguish effects of grazing from spatially co-occurring, but temporally segregated browsing are extremely rare. Here we use a set of long-term exclosures in northe...

  16. Spatially Heterogeneous Perturbations Homogenize the Regulation of Insect Herbivores.

    Science.gov (United States)

    Harvey, Eric; MacDougall, Andrew S

    2015-11-01

    Anthropogenic influences on resources and consumers can affect food web regulation, with impacts on trophic structure and ecosystem processes. Identifying how these impacts unfold is challenging because alterations to one or both resources and consumers can similarly transform community structure, especially for intermediate consumers. To date, empirical testing of perturbations on trophic regulation has been limited by the difficulty in separating the direct effect of perturbations on species composition and diversity from those unfolding indirectly via altered feeding pathways. Moreover, disentangling the independent and interactive impacts of covarying stressors that characterize human-altered systems has been an ongoing analytical challenge. We used a large-scale metacommunity experiment in grasslands to test how resource inputs, stand perturbation, and spatial factors affect regulation of insect herbivores in tritrophic grassland food webs. Using path-model comparisons, we observed significant simplification of food web regulation on insect herbivores, shifting from mixed predator-resource regulation in unaltered mainland areas to strictly resource-based regulation with landscape perturbation and fragmentation. Most changes were attributed to homogenization of plant community caused by landscape fragmentation and the deterministic influence of eutrophication that reduced among-patch beta diversity. This led to a simplified food web dominated by fewer but more abundant herbivore taxa. Our work implies that anthropogenic perturbation relating to resources and spatial isolation can transform the regulation of food web diversity, structure, and function.

  17. Spatially Heterogeneous Perturbations Homogenize the Regulation of Insect Herbivores.

    Science.gov (United States)

    Harvey, Eric; MacDougall, Andrew S

    2015-11-01

    Anthropogenic influences on resources and consumers can affect food web regulation, with impacts on trophic structure and ecosystem processes. Identifying how these impacts unfold is challenging because alterations to one or both resources and consumers can similarly transform community structure, especially for intermediate consumers. To date, empirical testing of perturbations on trophic regulation has been limited by the difficulty in separating the direct effect of perturbations on species composition and diversity from those unfolding indirectly via altered feeding pathways. Moreover, disentangling the independent and interactive impacts of covarying stressors that characterize human-altered systems has been an ongoing analytical challenge. We used a large-scale metacommunity experiment in grasslands to test how resource inputs, stand perturbation, and spatial factors affect regulation of insect herbivores in tritrophic grassland food webs. Using path-model comparisons, we observed significant simplification of food web regulation on insect herbivores, shifting from mixed predator-resource regulation in unaltered mainland areas to strictly resource-based regulation with landscape perturbation and fragmentation. Most changes were attributed to homogenization of plant community caused by landscape fragmentation and the deterministic influence of eutrophication that reduced among-patch beta diversity. This led to a simplified food web dominated by fewer but more abundant herbivore taxa. Our work implies that anthropogenic perturbation relating to resources and spatial isolation can transform the regulation of food web diversity, structure, and function. PMID:26655775

  18. Herbivorous ecomorphology and specialization patterns in theropod dinosaur evolution.

    Science.gov (United States)

    Zanno, Lindsay E; Makovicky, Peter J

    2011-01-01

    Interpreting key ecological parameters, such as diet, of extinct organisms without the benefit of direct observation or explicit fossil evidence poses a formidable challenge for paleobiological studies. To date, dietary categorizations of extinct taxa are largely generated by means of modern analogs; however, for many species the method is subject to considerable ambiguity. Here we present a refined approach for assessing trophic habits in fossil taxa and apply the method to coelurosaurian dinosaurs--a clade for which diet is particularly controversial. Our findings detect 21 morphological features that exhibit statistically significant correlations with extrinsic fossil evidence of coelurosaurian herbivory, such as stomach contents and a gastric mill. These traits represent quantitative, extrinsically founded proxies for identifying herbivorous ecomorphology in fossils and are robust despite uncertainty in phylogenetic relationships among major coelurosaurian subclades. The distribution of these features suggests that herbivory was widespread among coelurosaurians, with six major subclades displaying morphological evidence of the diet, and that contrary to previous thought, hypercarnivory was relatively rare and potentially secondarily derived. Given the potential for repeated, independent evolution of herbivory in Coelurosauria, we also test for repetitive patterns in the appearance of herbivorous traits within sublineages using rank concordance analysis. We find evidence for a common succession of increasing specialization to herbivory in the subclades Ornithomimosauria and Oviraptorosauria, perhaps underlain by intrinsic functional and/or developmental constraints, as well as evidence indicating that the early evolution of a beak in coelurosaurians correlates with an herbivorous diet. PMID:21173263

  19. Transcriptome Analysis of Green Peach Aphid (Myzus persicae): Insight into Developmental Regulation and Inter-Species Divergence

    Science.gov (United States)

    Ji, Rui; Wang, Yujun; Cheng, Yanbin; Zhang, Meiping; Zhang, Hong-Bin; Zhu, Li; Fang, Jichao; Zhu-Salzman, Keyan

    2016-01-01

    Green peach aphid (Myzus persicae) and pea aphid (Acyrthosiphon pisum) are two phylogenetically closely related agricultural pests. While pea aphid is restricted to Fabaceae, green peach aphid feeds on hundreds of plant species from more than 40 families. Transcriptome comparison could shed light on the genetic factors underlying the difference in host range between the two species. Furthermore, a large scale study contrasting gene expression between immature nymphs and fully developed adult aphids would fill a previous knowledge gap. Here, we obtained transcriptomic sequences of green peach aphid nymphs and adults, respectively, using Illumina sequencing technology. A total of 2244 genes were found to be differentially expressed between the two developmental stages, many of which were associated with detoxification, hormone production, cuticle formation, metabolism, food digestion, and absorption. When searched against publically available pea aphid mRNA sequences, 13,752 unigenes were found to have no homologous counterparts. Interestingly, many of these unigenes that could be annotated in other databases were involved in the “xenobiotics biodegradation and metabolism” pathway, suggesting the two aphids differ in their adaptation to secondary metabolites of host plants. Conversely, 3989 orthologous gene pairs between the two species were subjected to calculations of synonymous and nonsynonymous substitutions, and 148 of the genes potentially evolved in response to positive selection. Some of these genes were predicted to be associated with insect-plant interactions. Our study has revealed certain molecular events related to aphid development, and provided some insight into biological variations in two aphid species, possibly as a result of host plant adaptation.

  20. 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.

  1. Changes in monoterpene emission rates of Quercus ilex infested by aphids tended by native or invasive Lasius ant species.

    Science.gov (United States)

    Paris, Carolina I; Llusia, Joan; Peñuelas, Josep

    2010-07-01

    The emission of volatile organic compounds (VOCs) depends on temperature and light. Other factors such as insect herbivory also may modify VOC emission. In particular, aphid feeding promotes the release of new compounds and changes the composition of plant volatile blends. Given that some aphids are tended by ants, we investigated whether ants change the emission of VOCs indirectly through attendance on aphids. The effect of Lachnus roboris aphids and two different tending ant species on terpene emission rates of 4-year-old holm oak (Quercus ilex) saplings was investigated during a field experiment. There were five treatments: saplings alone (T1), saplings infested with L. roboris aphids (T2), saplings infested with aphids tended by the local ant Lasius grandis (T3), those tended by small colonies of the invasive ant Lasius neglectus (T4), and those tended by large colonies of the same invasive ant species (T5). The infestation by L. roboris elicited the emission of Delta(3)-carene and increased the emission of myrcene and gamma-terpinene. Terpene emissions were modified depending on the tending ant species. Attendance by the local ant L. grandis increased alpha and beta-pinene and sabinene. Attendance by the invasive ant L. neglectus only decreased significantly the emission of myrcene, one of the major compounds of the Q. ilex blend. Aphid abundance decreased with time for all treatments, but there was no difference in aphid abundance among treatments. Total terpene emission rates were not correlated with aphid abundance. These results highlight that aphids and tending ants may change terpene emission rates, depending on the ant species. PMID:20549328

  2. Herbivore preference for native vs. exotic plants: generalist herbivores from multiple continents prefer exotic plants that are evolutionarily naïve.

    Science.gov (United States)

    Morrison, Wendy E; Hay, Mark E

    2011-01-01

    Enemy release and biotic resistance are competing, but not mutually exclusive, hypotheses addressing the success or failure of non-native plants entering a new region. Enemy release predicts that exotic plants become invasive by escaping their co-adapted herbivores and by being unrecognized or unpalatable to native herbivores that have not been selected to consume them. In contrast, biotic resistance predicts that native generalist herbivores will suppress exotic plants that will not have been selected to deter these herbivores. We tested these hypotheses using five generalist herbivores from North or South America and nine confamilial pairs of native and exotic aquatic plants. Four of five herbivores showed 2.4-17.3 fold preferences for exotic over native plants. Three species of South American apple snails (Pomacea sp.) preferred North American over South American macrophytes, while a North American crayfish Procambarus spiculifer preferred South American, Asian, and Australian macrophytes over North American relatives. Apple snails have their center of diversity in South America, but a single species (Pomacea paludosa) occurs in North America. This species, with a South American lineage but a North American distribution, did not differentiate between South American and North American plants. Its preferences correlated with preferences of its South American relatives rather than with preferences of the North American crayfish, consistent with evolutionary inertia due to its South American lineage. Tests of plant traits indicated that the crayfish responded primarily to plant structure, the apple snails primarily to plant chemistry, and that plant protein concentration played no detectable role. Generalist herbivores preferred non-native plants, suggesting that intact guilds of native, generalist herbivores may provide biotic resistance to plant invasions. Past invasions may have been facilitated by removal of native herbivores, introduction of non

  3. EVALUATION OF DIFFERENT SYNTHETIC AND BOTANICAL INSECTICIDE AGAINST APHID, APHIS GOSSYPII GLOVER INFESTING ISABGOL CROP

    Directory of Open Access Journals (Sweden)

    B. R. PATEL

    2013-01-01

    Full Text Available An investigation was carried out during 2008-09 to evaluate the different insecticides against aphid, Aphisgossypii Glover infesting isabgol (Plantago ovata crop under field condition at Sardarkrushinagar, S. D. A. U.,Dantiwada. The result of the field study revealed that, among all the chemical and botanical insecticides used,carbosulfan @ 0.05 per cent was found to be most effective by recording lowest population of aphid as per aphidindexing method (0.99 A. I. with the highest seed yield, 11.24 q/ha and neem oil @ 0.5 per cent was superiorthan other botanical recording (1.83 A. I. with a maximum 7.21 q/ha seed yield. Thus, from the overall resultsit can be concluded that the carbosulfan @ 0.05 and neem oil 0.5 per cent proved most effective for themanagement of aphid A. gossypii in isabgol crop.

  4. Bad housekeeping: why do aphids leave their exuviae inside the colony?

    Directory of Open Access Journals (Sweden)

    Boivin Guy

    2008-12-01

    Full Text Available Abstract Background Animals can gain protection against predators and parasites by living in groups. The encounter-dilution effect provides protection when the probability of detection of a group does not increase in proportion to group size (i.e. encounter effect, so that predators do not offset the encounter effect by attacking more members of the group (i.e. dilution effect. In this paper, we propose a novel mechanism by which prey insects could gain by producing decoys that act as multiple targets for predators or parasitoids if these decoys are recognised as preys or hosts and negatively affect the patch foraging strategy of these predators and parasitoids. Such a decoy mechanism could be present in aphid colonies in which aphid exuviae are recognised and attacked by Aphidiine wasps. Results We conducted a behavioural study to evaluate the effect of exuviae on parasitoid patch residence time and egg allocation in experimental aphid patches with or without exuviae. We showed that exuviae are recognised and attacked at the same level as aphids when both are present in the patch. While parasitism rate was not significantly lower in patches with exuviae when the parasitoid left the patch, the time wasted by parasitoids to handle exuviae did influence the patch residence time. As a consequence, the attack rate on the live aphids was lower in patches that contain exuviae. Conclusion Aphids had more time available to flee and thus each individual might gain protection against parasitoids by leaving their exuviae near and within the colony. These results demonstrate that the encounter-dilution effect provided by living in a group can be enhanced by extra-materials that act as decoy for natural enemies.

  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. Natural enemies act faster than endophytic fungi in population control of cereal aphids.

    Science.gov (United States)

    Härri, Simone A; Krauss, Jochen; Müller, Christine B

    2008-05-01

    1. Fast-growing populations of phytophagous insects can be limited by the presence of natural enemies and by alkaloids that are produced by symbiotic associations of many temperate grass species with endophytic fungi. It is unclear if and how acquired plant defences derived from endophytic fungi interact with natural enemies to affect phytophagous insect populations. 2. To assess the relative importance of endophytic fungi compared to that of natural enemies on the population dynamics of phytophagous insects, we carried out a fully factorial field experiment, in which the presence of natural enemies and the presence of endophytic fungi were manipulated simultaneously. Target colonies of aphids were monitored for 8 weeks starting from their natural appearance in the field to the end of the aphid season. 3. We show that on Lolium perenne increased natural enemy densities reduced the individual numbers of two common cereal aphids, Rhopalosiphum padi and Metopolophium festucae. 4. The presence of the endophytic fungi Neotyphodium lolii reduced the number of M. festucae but did not affect the number of R. padi. The reduction in R. padi numbers by predators and parasitoids was not influenced by the presence of endophytes. For adult M. festucae, however, the negative effects of natural enemies were significant only in the absence of endophytes. 5. Over the duration of the experiment, the effect of natural enemies on aphid colony growth was much stronger than the effect of the endophytic fungi N. lolii, presumably because predator and parasitoid action on aphid colonies is much faster than any effects of endophytes. 6. Our results demonstrate that with simultaneous action of acquired endosymbionts and natural enemies, both factors can control aphid colony growth but they generally act independently of each other.

  7. Adaptation of a polyphagous herbivore to a novel host plant extensively shapes the transcriptome of herbivore and host.

    Science.gov (United States)

    Wybouw, Nicky; Zhurov, Vladimir; Martel, Catherine; Bruinsma, Kristie A; Hendrickx, Frederik; Grbić, Vojislava; Van Leeuwen, Thomas

    2015-09-01

    Generalist arthropod herbivores rapidly adapt to a broad range of host plants. However, the extent of transcriptional reprogramming in the herbivore and its hosts associated with adaptation remains poorly understood. Using the spider mite Tetranychus urticae and tomato as models with available genomic resources, we investigated the reciprocal genomewide transcriptional changes in both spider mite and tomato as a consequence of mite's adaptation to tomato. We transferred a genetically diverse mite population from bean to tomato where triplicated populations were allowed to propagate for 30 generations. Evolving populations greatly increased their reproductive performance on tomato relative to their progenitors when reared under identical conditions, indicative of genetic adaptation. Analysis of transcriptional changes associated with mite adaptation to tomato revealed two main components. First, adaptation resulted in a set of mite genes that were constitutively downregulated, independently of the host. These genes were mostly of an unknown function. Second, adapted mites mounted an altered transcriptional response that had greater amplitude of changes when re-exposed to tomato, relative to nonadapted mites. This gene set was enriched in genes encoding detoxifying enzymes and xenobiotic transporters. Besides the direct effects on mite gene expression, adaptation also indirectly affected the tomato transcriptional responses, which were attenuated upon feeding of adapted mites, relative to the induced responses by nonadapted mite feeding. Thus, constitutive downregulation and increased transcriptional plasticity of genes in a herbivore may play a central role in adaptation to host plants, leading to both a higher detoxification potential and reduced production of plant defence compounds. PMID:26211543

  8. Synaptic Vesicle Recycling Is Unaffected in the Ts65Dn Mouse Model of Down Syndrome.

    Science.gov (United States)

    Marland, Jamie R K; Smillie, Karen J; Cousin, Michael A

    2016-01-01

    Down syndrome (DS) is the most common genetic cause of intellectual disability, and arises from trisomy of human chromosome 21. Accumulating evidence from studies of both DS patient tissue and mouse models has suggested that synaptic dysfunction is a key factor in the disorder. The presence of several genes within the DS trisomy that are either directly or indirectly linked to synaptic vesicle (SV) endocytosis suggested that presynaptic dysfunction could underlie some of these synaptic defects. Therefore we determined whether SV recycling was altered in neurons from the Ts65Dn mouse, the best characterised model of DS to date. We found that SV exocytosis, the size of the SV recycling pool, clathrin-mediated endocytosis, activity-dependent bulk endocytosis and SV generation from bulk endosomes were all unaffected by the presence of the Ts65Dn trisomy. These results were obtained using battery of complementary assays employing genetically-encoded fluorescent reporters of SV cargo trafficking, and fluorescent and morphological assays of fluid-phase uptake in primary neuronal culture. The absence of presynaptic dysfunction in central nerve terminals of the Ts65Dn mouse suggests that future research should focus on the established alterations in excitatory / inhibitory balance as a potential route for future pharmacotherapy.

  9. Synaptic Vesicle Recycling Is Unaffected in the Ts65Dn Mouse Model of Down Syndrome.

    Directory of Open Access Journals (Sweden)

    Jamie R K Marland

    Full Text Available Down syndrome (DS is the most common genetic cause of intellectual disability, and arises from trisomy of human chromosome 21. Accumulating evidence from studies of both DS patient tissue and mouse models has suggested that synaptic dysfunction is a key factor in the disorder. The presence of several genes within the DS trisomy that are either directly or indirectly linked to synaptic vesicle (SV endocytosis suggested that presynaptic dysfunction could underlie some of these synaptic defects. Therefore we determined whether SV recycling was altered in neurons from the Ts65Dn mouse, the best characterised model of DS to date. We found that SV exocytosis, the size of the SV recycling pool, clathrin-mediated endocytosis, activity-dependent bulk endocytosis and SV generation from bulk endosomes were all unaffected by the presence of the Ts65Dn trisomy. These results were obtained using battery of complementary assays employing genetically-encoded fluorescent reporters of SV cargo trafficking, and fluorescent and morphological assays of fluid-phase uptake in primary neuronal culture. The absence of presynaptic dysfunction in central nerve terminals of the Ts65Dn mouse suggests that future research should focus on the established alterations in excitatory / inhibitory balance as a potential route for future pharmacotherapy.

  10. First record of the adventive oriental aphid Schizaphis piricola (Matsumura, 1917 (Hemiptera, Aphididae in Europe

    Directory of Open Access Journals (Sweden)

    Nicolás Pérez-Hidalgo

    2011-04-01

    Full Text Available The oriental aphid Schizaphis piricola Matsumura, is recorded for the first time in Europe, on the ornamental pear tree Pyrus calleryana in landscaped areas in Madrid (Spain. Data on the morphology of the primary host (apterous and alate fundatrigeniae and fundatrices, and their biology and distribution are given. The keys for identifying species of Schizaphis (Schizaphis in the Iberian Peninsula are updated. Two species of aphids are also recorded for the first time on Pyrus calleryana: S. piricola and Aphis pomi.

  11. 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. .

  12. Comparative analysis of Solanum stoloniferum responses to probing by the green peach aphid Myzus persicae and the potato aphid Macrosiphum euphorbiae

    Institute of Scientific and Technical Information of China (English)

    Adriana E.Alvarez; Viviana G.Broglia; Anahí M.Alberti D'Amato; Doret Wouters; Edwin van der Vossen; Elisa Garzo; W.Fred Tjallingii

    2013-01-01

    Plants protect themselves against aphid attacks by species-specific defense mechanisms.Previously,we have shown that Solanum stoloniferum Schlechtd has resistance factors to Myzus persicae Sulzer (Homoptera:Aphididae) at the epidermal/mesophyll level that are not effective against Macrosiphum euphorbiae Thomas (Homoptera:Aphididae).Here,we compare the nymphal mortality,the pre-reproductive development time,and the probing behavior of M.persicae and M.euphorbiae on S.stoloniferum and Solanum tuberosum L.Furthermore,we analyze the changes in gene expression in S.stoloniferum 96 hours post infestation by either aphid species.Although the M.euphorbiae probing behavior shows that aphids encounter more probing constrains on phloem activities-longer probing and salivation time-on S.stoloniferum than on S.tuberosum,the aphids succeeded in reaching a sustained ingestion of phloem sap on both plants.Probing by M.persicae on S.stoloniferum plants resulted in limited feeding only.Survival of M.euphorbiae and M.persicae was affected on young leaves,but not on senescent leaves of S.stoloniferum.Infestation by M.euphorbiae changed the expression of more genes than M.persicae did.At the systemic level both aphids elicited a weak response.Infestation of S.stoloniferum plants with a large number ofM.persicae induced morphological changes in the leaves,leading to the development of pustules that were caused by disrupted vascular parenchyma and surrounding tissue.In contrast,an infestation by M.euphorbiae had no morphological effects.Both plant species can be regarded as good host for M.euphorbiae,whereas only S.tuberosum is a good host for Mo persicae and S.stoloniferum is not.Infestation of S.stoloniferum by M.persicae or M.euphorbiae changed the expression of a set of plant genes specific for each of the aphids as well as a set of common genes.

  13. 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)

    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)

  14. Mammalian Herbivores Alter the Population Growth and Spatial Establishment of an Early-Establishing Grassland Species.

    Science.gov (United States)

    Sullivan, Lauren L; Danielson, Brent J; Harpole, W Stanley

    2016-01-01

    Plant-herbivore interactions influence the establishment context of plant species, as herbivores alter the community context in which individual species establish, and the spatial relationship between individuals and their source population as plants invade. This relationship can be described using an establishment kernel, which takes into account movement through seed dispersal, and subsequent establishment of adults. Mammalian herbivores are hypothesized to influence plant population growth and establishment through a combination of consumption of seeds and seedlings, and movement of seeds. While the movement abilities of plants are well known, we have very few empirical mechanistic tests of how biotic factors like mammalian herbivores influence this spread potential. As herbivores of all sizes are abundant on the landscape, we asked the question, how do mammalian herbivores influence the population growth, spatial establishment, and the community establishment context of an early-recruiting native prairie legume, Chamaecrista fasciculata? We planted C. fasciculata in source populations within a four-acre tallgrass prairie restoration in plots with and without herbivores, and monitored its establishment with respect to distance from the source populations. We found that herbivores decreased population growth, and decreased the mean and range establishment distance. Additionally, C. fasciculata established more often without herbivores, and when surrounded by weedy, annual species. Our results provide insight into how the interactions between plants and herbivores can alter the spatial dynamics of developing plant communities, which is vital for colonization and range spread with fragmentation and climate change. Mammalian herbivores have the potential to both slow rates of establishment, but also determine the types of plant communities that surround invading species. Therefore, it is essential to consider the herbivore community when attempting to restore

  15. Below-ground herbivory limits induction of extrafloral nectar by above-ground herbivores

    OpenAIRE

    Huang, Wei; Siemann, Evan; Carrillo, Juli; Ding, Jianqing

    2015-01-01

    Background and Aims Many plants produce extrafloral nectar (EFN), and increase production following above-ground herbivory, presumably to attract natural enemies of the herbivores. Below-ground herbivores, alone or in combination with those above ground, may also alter EFN production depending on the specificity of this defence response and the interactions among herbivores mediated through plant defences. To date, however, a lack of manipulative experiments investigating EFN production induc...

  16. Colimitation of a freshwater herbivore by sterols and polyunsaturated fatty acids

    OpenAIRE

    Martin-Creuzburg, Dominik; Sperfeld, Erik; Wacker, Alexander

    2009-01-01

    Empirical data providing evidence for a colimitation of an herbivore by two or more essential nutrients are scarce, particularly in regard to biochemical resources. Here, a graphical model is presented, which describes the growth of an herbivore in a system with two potentially limiting resources. To verify this model, life-history experiments were conducted with the herbivore Daphnia magna feeding on the picocyanobacterium Synechococcus elongatus, which was supplemented with increasing amoun...

  17. Can the Evolution of Plant Defense Lead to Plant-Herbivore Mutualism?

    OpenAIRE

    de Mazancourt, C; Loreau, M; Dieckmann, U

    2001-01-01

    Moderate rates of herbivory can enhance primary production. This hypothesis has led to a controversy as to whether such positive effects can result in mutualistic interactions between plants and herbivores. We present a model for the ecology and evolution of plant-herbivore systems to address this question. In this model, herbivores have a positive indirect effect on plants through recycling of a limiting nutrient. Plants can evolve but are constrained by a trade-off between growth and antihe...

  18. Voxel-based morphometry analysis reveals frontal brain differences in participants with ADHD and their unaffected siblings

    Science.gov (United States)

    Bralten, Janita; Greven, Corina U.; Franke, Barbara; Mennes, Maarten; Zwiers, Marcel P.; Rommelse, Nanda N.J.; Hartman, Catharina; van der Meer, Dennis; O’Dwyer, Laurence; Oosterlaan, Jaap; Hoekstra, Pieter J.; Heslenfeld, Dirk; Arias-Vasquez, Alejandro; Buitelaar, Jan K.

    2016-01-01

    Background Data on structural brain alterations in patients with attention-deficit/hyperactivity disorder (ADHD) have been inconsistent. Both ADHD and brain volumes have a strong genetic loading, but whether brain alterations in patients with ADHD are familial has been underexplored. We aimed to detect structural brain alterations in adolescents and young adults with ADHD compared with healthy controls. We examined whether these alterations were also found in their unaffected siblings, using a uniquely large sample. Methods We performed voxel-based morphometry analyses on MRI scans of patients with ADHD, their unaffected siblings and typically developing controls. We identified brain areas that differed between participants with ADHD and controls and investigated whether these areas were different in unaffected siblings. Influences of medication use, age, sex and IQ were considered. Results Our sample included 307 patients with ADHD, 169 unaffected siblings and 196 typically developing controls (mean age 17.2 [range 8–30] yr). Compared with controls, participants with ADHD had significantly smaller grey matter volume in 5 clusters located in the precentral gyrus, medial and orbitofrontal cortex, and (para)cingulate cortices. Unaffected siblings showed intermediate volumes significantly different from controls in 4 of these clusters (all except the precentral gyrus). Medication use, age, sex and IQ did not have an undue influence on the results. Limitations Our sample was heterogeneous, most participants with ADHD were taking medication, and the comparison was cross-sectional. Conclusion Brain areas involved in decision making, motivation, cognitive control and motor functioning were smaller in participants with ADHD than in controls. Investigation of unaffected siblings indicated familiality of 4 of the structural brain differences, supporting their potential in molecular genetic analyses in ADHD research. PMID:26679925

  19. The impact of plant chemical diversity on plant-herbivore interactions at the community level.

    Science.gov (United States)

    Salazar, Diego; Jaramillo, Alejandra; Marquis, Robert J

    2016-08-01

    Understanding the role of diversity in ecosystem processes and species interactions is a central goal of ecology. For plant-herbivore interactions, it has been hypothesized that when plant species diversity is reduced, loss of plant biomass to herbivores increases. Although long-standing, this hypothesis has received mixed support. Increasing plant chemical diversity with increasing plant taxonomic diversity is likely to be important for plant-herbivore interactions at the community level, but the role of chemical diversity is unexplored. Here we assess the effect of volatile chemical diversity on patterns of herbivore damage in naturally occurring patches of Piper (Piperaceae) shrubs in a Costa Rican lowland wet forest. Volatile chemical diversity negatively affected total, specialist, and generalist herbivore damage. Furthermore, there were differences between the effects of high-volatility and low-volatility chemical diversity on herbivore damage. High-volatility diversity reduced specialist herbivory, while low-volatility diversity reduced generalist herbivory. Our data suggest that, although increased plant diversity is expected to reduce average herbivore damage, this pattern is likely mediated by the diversity of defensive compounds and general classes of anti-herbivore traits, as well as the degree of specialization of the herbivores attacking those plants. PMID:27129320

  20. Use of slow-release plant infochemicals to control aphids: a first investigation in a Belgian wheat field.

    Science.gov (United States)

    Zhou, Haibo; Chen, Longsheng; Liu, Yong; Chen, Julian; Francis, Frédéric

    2016-01-01

    Using infochemicals to develop a push-pull strategy in pest control is a potential way to promote sustainable crop production. Infochemicals from plant essential oils were mixed with paraffin oil for slow release in field experiments on wheat to control the population density of cereal aphids and to enhance their natural enemies. (Z)-3-Hexenol (Z3H) attracted Metopolophum dirhodum and Sitobion avenae, the predominant species on wheat in Belgium, and may be a useful infochemical for aphid control by attracting aphids away from field plots. Release of (E)-β-farnesene (EBF) or a garlic extract (GE) led to a significant decrease in the abundance of wheat aphids. The main natural enemies of cereal aphids found were lacewings (47.8%), hoverflies (39.4%), and ladybirds (12.8%). Ladybird abundance varied little before the end of the wheat-growing season. Our results suggest that these chemicals can form the basis of a "push-pull" strategy for aphid biological control, with GE and EBF acting as a pest- and beneficial-pulling stimulus and Z3H for aphid pulling. PMID:27530318

  1. 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.

  2. 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.

  3. Use of slow-release plant infochemicals to control aphids: a first investigation in a Belgian wheat field.

    Science.gov (United States)

    Zhou, Haibo; Chen, Longsheng; Liu, Yong; Chen, Julian; Francis, Frédéric

    2016-08-17

    Using infochemicals to develop a push-pull strategy in pest control is a potential way to promote sustainable crop production. Infochemicals from plant essential oils were mixed with paraffin oil for slow release in field experiments on wheat to control the population density of cereal aphids and to enhance their natural enemies. (Z)-3-Hexenol (Z3H) attracted Metopolophum dirhodum and Sitobion avenae, the predominant species on wheat in Belgium, and may be a useful infochemical for aphid control by attracting aphids away from field plots. Release of (E)-β-farnesene (EBF) or a garlic extract (GE) led to a significant decrease in the abundance of wheat aphids. The main natural enemies of cereal aphids found were lacewings (47.8%), hoverflies (39.4%), and ladybirds (12.8%). Ladybird abundance varied little before the end of the wheat-growing season. Our results suggest that these chemicals can form the basis of a "push-pull" strategy for aphid biological control, with GE and EBF acting as a pest- and beneficial-pulling stimulus and Z3H for aphid pulling.

  4. Use of slow-release plant infochemicals to control aphids: a first investigation in a Belgian wheat field

    Science.gov (United States)

    Zhou, Haibo; Chen, Longsheng; Liu, Yong; Chen, Julian; Francis, Frédéric

    2016-01-01

    Using infochemicals to develop a push–pull strategy in pest control is a potential way to promote sustainable crop production. Infochemicals from plant essential oils were mixed with paraffin oil for slow release in field experiments on wheat to control the population density of cereal aphids and to enhance their natural enemies. (Z)-3-Hexenol (Z3H) attracted Metopolophum dirhodum and Sitobion avenae, the predominant species on wheat in Belgium, and may be a useful infochemical for aphid control by attracting aphids away from field plots. Release of (E)-β-farnesene (EBF) or a garlic extract (GE) led to a significant decrease in the abundance of wheat aphids. The main natural enemies of cereal aphids found were lacewings (47.8%), hoverflies (39.4%), and ladybirds (12.8%). Ladybird abundance varied little before the end of the wheat-growing season. Our results suggest that these chemicals can form the basis of a “push–pull” strategy for aphid biological control, with GE and EBF acting as a pest- and beneficial-pulling stimulus and Z3H for aphid pulling. PMID:27530318

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

    Science.gov (United States)

    Rausch, Michael A; Chougule, Nanasaheb P; Deist, Benjamin R; Bonning, Bryony C

    2016-01-01

    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. PMID:27171411

  6. Identification of Critical Conditions for Immunostaining in the Pea Aphid Embryos: Increasing Tissue Permeability and Decreasing Background Staining.

    Science.gov (United States)

    Lin, Gee-Way; Chang, Chun-che

    2016-01-01

    The pea aphid Acyrthosiphon pisum, with a sequenced genome and abundant phenotypic plasticity, has become an emerging model for genomic and developmental studies. Like other aphids, A. pisum propagate rapidly via parthenogenetic viviparous reproduction, where the embryos develop within egg chambers in an assembly-line fashion in the ovariole. Previously we have established a robust platform of whole-mount in situ hybridization allowing detection of mRNA expression in the aphid embryos. For analyzing the expression of protein, though, established protocols for immunostaining the ovarioles of asexual viviparous aphids did not produce satisfactory results. Here we report conditions optimized for increasing tissue permeability and decreasing background staining, both of which were problems when applying established approaches. Optimizations include: (1) incubation of proteinase K (1 µg/ml, 10 min), which was found essential for antibody penetration in mid- and late-stage aphid embryos; (2) replacement of normal goat serum/bovine serum albumin with a blocking reagent supplied by a Digoxigenin (DIG)-based buffer set and (3) application of methanol rather hydrogen peroxide (H2O2) for bleaching endogenous peroxidase; which significantly reduced the background staining in the aphid tissues. These critical conditions optimized for immunostaining will allow effective detection of gene products in the embryos of A. pisum and other aphids. PMID:26862939

  7. Identification of histological patterns in clinically affected and unaffected palm regions in dupuytren's disease.

    Directory of Open Access Journals (Sweden)

    Camilo-Andrés Alfonso-Rodríguez

    Full Text Available Dupuytren's disease is a fibro-proliferative disease characterized by a disorder of the extracellular matrix (ECM and high myofibroblast proliferation. However, studies failed to determine if the whole palm fascia is affected by the disease. The objective of this study was to analyze several components of the extracellular matrix of three types of tissues-Dupuytren's diseased contracture cords (DDC, palmar fascia clinically unaffected by Dupuytren's disease contracture (NPF, and normal forehand fascia (NFF. Histological analysis, quantification of cells recultured from each type of tissue, mRNA microarrays and immunohistochemistry for smooth muscle actin (SMA, fibrillar ECM components and non-fibrillar ECM components were carried out. The results showed that DDC samples had abundant fibrosis with reticular fibers and few elastic fibers, high cell proliferation and myofibroblasts, laminin and glycoproteins, whereas NFF did not show any of these findings. Interestingly, NPF tissues had more cells showing myofibroblasts differentiation and more collagen and reticular fibers, laminin and glycoproteins than NFF, although at lower level than DDC, with similar elastic fibers than DDC. Immunohistochemical expression of decorin was high in DDC, whereas versican was highly expressed NFF, with no differences for aggrecan. Cluster analysis revealed that the global expression profile of NPF was very similar to DDC, and reculturing methods showed that cells corresponding to DDC tissues proliferated more actively than NPF, and NPF more actively than NFF. All these results suggest that NPF tissues may be affected, and that a modification of the therapeutic approach used for the treatment of Dupuytren's disease should be considered.

  8. 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

    Full Text Available 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.

  9. Increased temperature reduces herbivore host-plant quality.

    Science.gov (United States)

    Bauerfeind, Stephanie S; Fischer, Klaus

    2013-11-01

    Globally increasing temperatures may strongly affect insect herbivore performance, as their growth and development is directly linked to ambient temperature as well as host-plant quality. In contrast to direct effects of temperature on herbivores, indirect effects mediated via thermal effects on host-plant quality are only poorly understood, despite having the potential to substantially impact performance and thereby to alter responses to the changing climatic conditions. We here use a full-factorial design to explore the direct (larvae were reared at 17 °C or 25 °C) and indirect effects (host plants were reared at 17 °C or 25 °C) of temperature on larval growth and life-history traits in the temperate-zone butterfly Pieris napi. Direct temperature effects reflected the common pattern of prolonged development and increased body mass at lower temperatures. At the higher temperature, efficiency of converting food into body matter was much reduced being accompanied by an increased food intake, suggesting compensatory feeding. Indirect temperature effects were apparent as reduced body mass, longer development time, an increased food intake, and a reduced efficiency of converting food into body matter in larvae feeding on plants grown at the higher temperature, thus indicating poor host-plant quality. The effects of host-plant quality were more pronounced at the higher temperature, at which compensatory feeding was much less efficient. Our results highlight that temperature-mediated changes in host-plant quality are a significant, but largely overlooked source of variation in herbivore performance. Such effects may exaggerate negative effects of global warming, which should be considered when trying to forecast species' responses to climate change.

  10. 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

  11. Reciprocal assistance for aphid transmission between non-transmissible strains of zucchini yellow mosaic potyvirus in mixed infections. Brief report.

    Science.gov (United States)

    Desbiez, C; Wipf-Scheibel, C; Lecoq, H

    1999-01-01

    Several aphid non-transmissible strains of zucchini yellow mosaic potyvirus (ZYMV) have been described, in relation with mutations in the two viral proteins required for transmissibility, coat protein and helper component. Assistance mechanisms were previously shown to allow transmission of such strains when functional proteins are provided in trans. In this paper, we used monoclonal antibodies to allow a specific detection of two aphid non-transmissible strains of ZYMV and we revealed that reciprocal assistance mechanisms can mediate simultaneous aphid transmission of these deficient strains. Potential epidemiological and evolutive consequences of such assistance mechanisms between variants in complex virus populations are discussed. PMID:10603175

  12. 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

  13. Parasitoids (Hymenoptera: Braconidae: Aphidiinae) of northeastern Iran: aphidiine-aphid-plant associations, key and description of a new species.

    Science.gov (United States)

    Rakhshani, Ehsan; Kazemzadeh, Sedigheh; Starý, Petr; Barahoei, Hossein; Kavallieratos, Nickolas G; Ćetković, Aleksandar; Popović, Anđelka; Bodlah, Lmran; Tomanović, Željko

    2012-01-01

    Aphid parasitoids of the subfamily Aphidiinae (Hymenoptera: Braconidae) of northeastern Iran were studied in this paper. A total of 29 species are keyed and illustrated with line drawings. The aphidiines presented in this work have been reared from 42 aphid host taxa occurring on 49 plant taxa from a total of 33 sampling sites. Sixty-six aphidiine-aphid-plant associations are presented. Trioxys metacarpalis sp. nov. from Chaitaphis tenuicaudata Nevsky (Hemiptera: Aphididae) on Kochia scoparia, is described. The species diversity based on the comparative faunistic analysis is discussed. PMID:23463939

  14. Shallot Aphids, Myzus ascalonicus, in Strawberry: Biocontrol Potential of Three Predators and Three Parasitoids

    DEFF Research Database (Denmark)

    Enkegaard, Annie; Sigsgaard, Lene; Kristensen, Kristian

    2013-01-01

    or sweet pepper leaves. The aphid species and the plant species did not, however, have a significant influence on the number of females laying eggs, the average number of eggs laid during the first day being 6.37±1.28 per female. Adult lady beetles had a significant preference for odor from controls...... without plants over odors from uninfested strawberry or pepper plants, but they showed no preference for either of the plant species, whether infested with aphids or not. The predation capacity of A. bipunctata on shallot aphids holds promise for its use in inundative biocontrol, and the results on egg...

  15. Energy budgets of the Chinese green lacewing (Neuroptera: Chrysopidae) and its potential for biological control of the cotton aphid (Homoptera: Aphididae)

    Institute of Scientific and Technical Information of China (English)

    FENG GAO; XIANG-HUI LIU; FENG GE

    2007-01-01

    Energy budgets of larval stages of the Chinese green lacewing, Chrysopa sinica (Tjeder) (Neuroptera: Chrysopidae) were determined under laboratory conditions at photoperiod of 14:10 L:D, 27±1℃ and 75%±2% RH. The energy used as ingestion,assimilation, respiration, productivity and feces was constructed for each developmental stage. In addition, under these experimental conditions, the potential of C.sinica as a biological control agent was evaluated according to the ingestion by this predator and the energy content of cotton aphid, Aphis gossypii (Glover) (Homoptera: Aphididae). The larval stage of C. sinica was able to consume 1281.4 1-day-old aphids, 1018.7 2-day-old aphids,626.9 3-day-old aphids, 393.5 4-day-old aphids, 312.1 5-day-old aphids or 203.5 9-day-old aphids, respectively. No significant difference was detected between the estimated number of aphids consumed by the lacewings using energetic methods and the actual number of aphids consumed by the lacewings in this experiment. Our results showed that C. sinica is an important natural enemy of the cotton aphid, and energetic methods are very useful to quantify biological control efficacy of natural enemies.

  16. Metabolic Engineering of Plant-derived (E)-β-farnesene Synthase Genes for a Novel Type of Aphid-resistant Genetically Modified Crop Plants

    Institute of Scientific and Technical Information of China (English)

    Xiu-Dao Yu; John Pickett; You-Zhi Ma; Toby Bruce; Johnathan Napier; Huw D.Jones; Lan-Qin Xia

    2012-01-01

    Aphids are major agricultural pests that cause significant yield losses of crop plants each year.Excessive dependence on insecticides for long-term aphid control is undesirable because of the development of insecticide resistance,the potential negative effects on non-target organisms and environmental pollution.Transgenic crops engineered for resistance to aphids via a non-toxic mode of action could be an efficient alternative strategy.(E)-β-Farnesene (EβF) synthases catalyze the formation of EβF,which for many pest aphids is the main component of the alarm pheromone involved in the chemical communication within these species.EβF can also be synthesized by certain plants but is then normally contaminated with inhibitory compounds.Engineering of crop plants capable of synthesizing and emitting EβF could cause repulsion of aphids and also the attraction of natural enemies that use EβF as a foraging cue,thus minimizing aphid infestation.In this review,the effects of aphids on host plants,plants' defenses against aphid herbivory and the recruitment of natural enemies for aphid control in an agricultural setting are briefly introduced.Furthermore,the plant-derived EβF synthase genes cloned to date along with their potential roles in generating novel aphid resistance via genetically modified approaches are discussed.

  17. First Complete Genome Sequence of Suakwa aphid-borne yellows virus from East Timor.

    Science.gov (United States)

    Maina, Solomon; Edwards, Owain R; de Almeida, Luis; Ximenes, Abel; Jones, Roger A C

    2016-01-01

    We present here the first complete genomic RNA sequence of the polerovirus Suakwa aphid-borne yellows virus (SABYV), from East Timor. The isolate sequenced came from a virus-infected pumpkin plant. The East Timorese genome had a nucleotide identity of 86.5% with the only other SABYV genome available, which is from Taiwan. PMID:27469955

  18. Registration of ‘Wyandot-14’ soybean with resistance to soybean aphid and powdery mildew

    Science.gov (United States)

    ‘Wyandot-14’ soybean [Glycine max (L.) Merr.] with resistance to soybean aphid biotypes 1 and 2 and resistance to powdery mildew was jointly released by the USDA-Agricultural Research Service and The Ohio Agricultural Research and Development Center (OARDC) as a late maturity group (MG) II (2.9) foo...

  19. The aphid Melanaphis sacchari and the weed Sorghum almum – Partners in crime

    Science.gov (United States)

    Sugarcane yellow leaf virus (SCYLV), the causal agent of yellow leaf disease of sugarcane, is widespread in Florida and vectored by the aphid Melanaphis sacchari. Sugarcane was the only known natural host of SCYLV in the USA until 2015 when a new natural host was found for this virus in Florida: Sor...

  20. Which shrubs and trees can conserve natural enemies of aphids in spring?

    NARCIS (Netherlands)

    P.C.J. van Rijn

    2014-01-01

    Habitats with shrubs and trees within the agricultural landscape may contribute to the maintenance of natural enemies of pests. Aphids and flowers are important resources for beneficial natural enemies such as ladybeetles, hoverflies and lacewings. Woody plants are the most likely candidates to prov

  1. Changes in large-scale climate alter spatial synchrony of aphid pests

    Science.gov (United States)

    Sheppard, Lawrence W.; Bell, James R.; Harrington, Richard; Reuman, Daniel C.

    2016-06-01

    Spatial synchrony, the tendency of distant populations to fluctuate similarly, is a major concern in ecology. Except in special circumstances, researchers historically had difficulty identifying drivers of synchrony in field systems. Perhaps for this reason, the possibility that changes in large-scale climatic drivers may modify synchrony, thereby impacting ecosystems and human concerns, has been little examined. Here, we use wavelets to determine environmental drivers of phenological synchrony across Britain for 20 aphid species, most major crop pests. Consistently across species, changes in drivers produced large changes in aphid synchrony. Different drivers acted on different timescales: using a new wavelet analogue of the Moran theorem, we show that on long timescales (>4 years), 80% of synchrony in aphid first flights is due to synchrony in winter climate; but this explanation accounts for less short-timescale (Changes in aphid synchrony over time also differed by timescale: long-timescale synchrony fell from before 1993 to after, caused by similar changes in winter climate; whereas short-timescale synchrony increased. Shifts in winter climate are attributable to the North Atlantic Oscillation, an important climatic phenomenon, so effects described here may influence other taxa. This study documents a new way that climatic changes influence populations, through altered Moran effects.

  2. Evaluation and reselection of wheat resistance to Russian wheat aphid biotype 2

    Science.gov (United States)

    Russian wheat aphid (RWA, Diuraphis noxia, Mordvilko) biotype 2 (RWA2) is virulent to most known RWA resistance genes and severely threatens wheat production in the hard winter wheat area of the US western Great Plains. We determined RWA2 reactions of 386 cultivars from China, 227 advanced breeding...

  3. Reproduction and Population Dynamics as Biotypic Markers of Russian Wheat Aphid Diuraphis noxia (Kurdjumov

    Directory of Open Access Journals (Sweden)

    Watson Ngenya

    2016-04-01

    Full Text Available Russian wheat aphid Diuraphis noxia (Kurdjumov is widely established in wheat-growing countries where it causes significant economic losses. The development and use of Russian wheat aphid (RWA-resistant wheat varieties has been constrained by the variation in resident RWA populations and the evolution of virulent biotypes. An experiment was set up at the Kenya Agricultural and Livestock Research Organization (KALRO, Njoro, to characterize RWA populations based on phenotypic characteristics of reproduction, development and population dynamics. RWA populations from the regions of Eldoret, Mau Narok and Njoro were used in the study. A factorial experiment was set up in randomized complete block design replicated eleven times. A single day-old nymph was placed on a new, fully-open leaf in a 0.5 cm-diameter clear plastic straw leaf cage and observed daily for its entire lifetime. The results showed that there were variations in aphid lifespan, reproductive longevity and aphid fecundity between populations, indicating that the phenotypic markers used to determine biotypes were good enough to show distinct biotypes among populations of the RWA in Kenya. Further, the study concluded that the use of phenotypic life and reproductive markers was a valid way of characterizing biotypes of RWA worldwide.

  4. Why the aphid Aphis spiraecola is more abundant on clementine tree than Aphis gossypii?

    Science.gov (United States)

    Mostefaoui, Houda; Allal-Benfekih, Leila; Djazouli, Zahr-Eddine; Petit, Daniel; Saladin, Gaëlle

    2014-02-01

    Aphis spiraecola and Aphis gossypii cause harmful damages on clementine tree orchards. Weekly surveys measured the abundance of aphids (larvae, winged and wingless adults) as well as of auxiliary insects and parameters of energy metabolism. Correlatively, soluble carbohydrates, total free amino acids, free proline and condensed tannins were quantified in control and infested leaves. Both aphid species showed parallel temporal variations, but A. spiraecola was consistently more abundant regardless of the stage. Amino acids had a positive effect on both aphid species abundance, but neither condensed tannins nor auxiliary insects seemed to modulate aphid populations. Interestingly, the leaf carbohydrate content was positively correlated with the abundance of A. spiraecola, but not with that of A. gossypii. Moreover, A. gossypii's abundance was significantly down-regulated by high proline concentrations. Thus, the higher abundance of A. spiraecola could be explained by a better tolerance to high proline contents and a better conversion of foliar energy metabolites.

  5. Enhancement of resistance to aphids by introducing the snowdrop lectin gene gna into maize plants.

    Science.gov (United States)

    Wang, Zhaoyu; Zhang, Kewei; Sun, Xiaofen; Tang, Kexuan; Zhang, Juren

    2005-12-01

    In order to enhance the resistance to pests, transgenic maize (Zea mays L.) plants from elite inbred lines containing the gene encoding snowdrop lectin (Galanthus nivalis L. agglutinin; GNA) under control of a phloem-specific promoter were generated through the Agrobacterium tumefaciens-mediated method. The toxicity of GNA-expressing plants to aphids has also been studied. The independently derived plants were subjected to molecular analyses. Polymerase chain reaction (PCR) and Southern blot analyses confirmed that the gna gene was integrated into maize genome and inherited to the following generations. The typical Mendelian patterns of inheritance occurred in most cases. The level of GNA expression at 0.13%-0.28% of total soluble protein was observed in different transgenic plants. The progeny of nine GNA-expressing independent transformants that were derived separately from the elite inbred lines DH4866, DH9942, and 8902, were selected for examination of resistance to aphids. These plants synthesized GNA at levels above 0.22% total soluble protein, and enhanced resistance to aphids was demonstrated by exposing the plants to corn leaf aphid (Rhopalosiphum maidis Fitch) under greenhouse conditions. The nymph production was significantly reduced by 46.9% on GNA-expressing plants. Field evaluation of the transgenic plants supported the results from the inoculation trial. After a series of artificial self-crosses, some homozygous transgenic maize lines expressing GNA were obtained. In the present study, we have obtained new insect-resistant maize material for further breeding work.

  6. [Study on transformation of snowdrop lectin gene to chrysanthemum and aphid resistance of the transgenic plants].

    Science.gov (United States)

    Wang, Guan-Lin; Liu, Yan-Hong; Guo, Shao-Hua; Wang, Yu; Ji, Yan; Fang, Hong-Jun

    2004-12-01

    Agrobacterium-mediated transformation in chrysanthemum was studied to prevent the insect pest of aphid (Mizus persicae). The gna gene was successfully transferred into chrysanthemum by leaf dish, and 93 transgenic clones were obtained. The highest transformation frequency 11.21% was achieved on the optimization facts, which were medium YEB with pH5.6, bacterial concentration OD600 = 0.4, precultivation for one day, cocultivation for four days, the cocultivation media supplemented with GA3 0.5 mg/L and leaf explants growed for 45 days. The results from PCR and FQ-PCR analysis confirmed that gna gene was integrated into the genome of chrysanthemum plants. The insect bioassay with aphid showed that the aphid resistance of different transgenic plants was difference, and the rate of aphid population inhibition of them were from 10% to 84% with an average rate of 39.4%. The leaf-extracts from different transgenic plants showed varying actinties in red-blood cell bioassay.

  7. A possible novel black aphid control approach using plant growth regulators

    Science.gov (United States)

    The black pecan aphid, Melanocallis caryaefoliae (Davis) (Hemiptera: Aphididae), elicits localized chlorotic injury to pecan foliage in order to feed, thereby accelerating leaf senescence and defoliation. The action of certain plant growth regulators (i.e., forchlorfenuron, gibberellic acid and avi...

  8. Reproduction and Population Dynamics as Biotypic Markers of Russian Wheat Aphid Diuraphis noxia (Kurdjumov).

    Science.gov (United States)

    Ngenya, Watson; Malinga, Joyce; Tabu, Isaiah; Masinde, Emily

    2016-01-01

    Russian wheat aphid Diuraphis noxia (Kurdjumov) is widely established in wheat-growing countries where it causes significant economic losses. The development and use of Russian wheat aphid (RWA)-resistant wheat varieties has been constrained by the variation in resident RWA populations and the evolution of virulent biotypes. An experiment was set up at the Kenya Agricultural and Livestock Research Organization (KALRO), Njoro, to characterize RWA populations based on phenotypic characteristics of reproduction, development and population dynamics. RWA populations from the regions of Eldoret, Mau Narok and Njoro were used in the study. A factorial experiment was set up in randomized complete block design replicated eleven times. A single day-old nymph was placed on a new, fully-open leaf in a 0.5 cm-diameter clear plastic straw leaf cage and observed daily for its entire lifetime. The results showed that there were variations in aphid lifespan, reproductive longevity and aphid fecundity between populations, indicating that the phenotypic markers used to determine biotypes were good enough to show distinct biotypes among populations of the RWA in Kenya. Further, the study concluded that the use of phenotypic life and reproductive markers was a valid way of characterizing biotypes of RWA worldwide. PMID:27049398

  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. Registration of 'Stoneham' spring feed barley resistant to Russian wheat aphid

    Science.gov (United States)

    'Stoneham' (REG. No.; PI 641940) a Russian wheat aphid (RWA, Diuraphis noxia Kurdjumov)-resistant, spring, two-rowed, feed barley (Hordeum vulgare) tested as 97BX 27-132, was developed and released by the USDA-ARS, Stillwater, OK and Aberdeen, ID; Colorado State University; and the University of Neb...

  11. Response of Green Peach Aphids and Other Arthropods to Garlic Intercropped with Tobacco

    NARCIS (Netherlands)

    Lai, R.; You, M.; Lotz, L.A.P.; Vasseur, L.

    2011-01-01

    The green peach aphid, Myzus persicae (Sulzer), is an insect pest that causes extensive damage to tobacco (Nicotiana tabacum L.) in China. Field trials were conducted in 2008 and 2009 at Longyan in the Fujian Province (China) to evaluate the effects of garlic (Allium sativum L.) as a deterrent to gr

  12. Evaluation of mirid predatory bugs and release strategy for aphid control in sweet pepper

    NARCIS (Netherlands)

    Messelink, G.J.; Bloemhard, C.M.J.; Hoogerbrugge, H.; Schelt, van J.; Ingegno, B.L.; Tavella, L.

    2015-01-01

    Zoophytophagous predators of the family Miridae (Heteroptera), which feed both on plant and prey, often maintain a close relationship with certain host plants. In this study, we aimed to select a suitable mirid predatory bug for aphid control in sweet pepper. Four species were compared: Macrolophus

  13. Adaptive significance of gall formation for a gall-inducing aphids on Japanese elm trees.

    Science.gov (United States)

    Takei, Mami; Yoshida, Sayaka; Kawai, Takashi; Hasegawa, Morifumi; Suzuki, Yoshihito

    2015-01-01

    Insect galls are abnormal plant tissues induced by external stimuli from parasitizing insects. It has been suggested that the stimuli include phytohormones such as auxin and cytokinins produced by the insects. In our study on the role of hormones in gall induction by the aphid Tetraneura nigriabdominalis, it was found that feedback regulation related to auxin and cytokinin activity is absent in gall tissues, even though the aphids contain higher concentrations of those phytohormones than do plant tissues. Moreover, jasmonic acid signaling appears to be compromised in gall tissue, and consequently, the production of volatile organic compounds, which are a typical defense response of host plants to herbivory, is diminished. These findings suggest that these traits of the gall tissue benefit aphids, because the gall tissue is highly sensitive to auxin and cytokinin, which induce and maintain it. The induced defenses against aphid feeding are also compromised. The abnormal responsiveness to phytohormones is regarded as a new type of extended phenotype of gall-inducing insects. PMID:25437243

  14. 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. PMID:27289084

  15. Subcellular location of the helper component-proteinase of Cowpea Aphid-Borne Mosaic Virus

    NARCIS (Netherlands)

    Mlotshwa, S.; Verver, J.; Sithole-Niang, I.; Gopinath, K.; Carette, J.; Kammen, van A.; Wellink, J.

    2002-01-01

    The helper component-proteinase (HC-Pro) of Cowpea aphid-borne mosaic virus (CABMV) was expressed in Escherichia coli and used to obtain HC-Pro antiserum that was used as an analytical tool for HC-Pro studies. The antiserum was used in immunofluorescence assays to study the subcellular location of H

  16. 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.

  17. Effects of Insecticides on Strawberry Aphid Chaetosiphon fragaefolii (Cockerell) on Resistant and Susceptible Strawberry Genotypes

    OpenAIRE

    Slobodan Milenković; Dejan Marčić; Pantelija Perić

    2011-01-01

    Strawberry aphid, Chaetosiphon fragaefolii (Cockerell), is the most important vector of strawberry virus. Breeding of genotypes resistant to this pest is an important preventive control measure, which can be compatible with rational insecticide application. The aim of the paper was to determine effects of dimethoate and deltamethrin on C. fragaefolii populations reared on two strawberry genotypes different in susceptibility: susceptible strawberry cultivar ...

  18. Proteins involved in attack and defence in Zygomycete-aphid interactions

    DEFF Research Database (Denmark)

    Grell, Morten Nedergaard; Jensen, Annette Bruun; Lange, Lene

    2009-01-01

    a secretome study of field collected grain aphids (Sitobion avenae) in early stages of infection with entomophthoralean fungi using the transposon assisted signal trapping (TAST) technology (Becker et al. 2004, J Microbiol Methods 57, 123-133), thereby discovering a series of secreted enzymes of the pathogens...

  19. Enhancement of resistance to aphids by introducing the snowdrop lectin gene gna into maize plants

    Indian Academy of Sciences (India)

    Zhaoyu Wang; Kewei Zhang; Xiaofen Sun; Kexuan Tang; Juren Zhang

    2005-12-01

    In order to enhance the resistance to pests, transgenic maize (Zea mays L.) plants from elite inbred lines containing the gene encoding snowdrop lectin (Galanthus nivalis L. agglutinin; GNA) under control of a phloemspecific promoter were generated through the Agrobacterium tumefaciens-mediated method. The toxicity of GNA-expressing plants to aphids has also been studied. The independently derived plants were subjected to molecular analyses. Polymerase chain reaction (PCR) and Southern blot analyses confirmed that the gna gene was integrated into maize genome and inherited to the following generations. The typical Mendelian patterns of inheritance occurred in most cases. The level of GNA expression at 0.13%–0.28% of total soluble protein was observed in different transgenic plants. The progeny of nine GNA-expressing independent transformants that were derived separately from the elite inbred lines DH4866, DH9942, and 8902, were selected for examination of resistance to aphids. These plants synthesized GNA at levels above 0.22% total soluble protein, and enhanced resistance to aphids was demonstrated by exposing the plants to corn leaf aphid (Rhopalosiphum maidis Fitch) under greenhouse conditions. The nymph production was significantly reduced by 46.9% on GNA-expressing plants. Field evaluation of the transgenic plants supported the results from the inoculation trial. After a series of artificial self-crosses, some homozygous transgenic maize lines expressing GNA were obtained. In the present study, we have obtained new insect-resistant maize material for further breeding work.

  20. MRI-based brain structure volumes in temporal lobe epilepsy patients and their unaffected siblings: a preliminary study.

    LENUS (Irish Health Repository)

    Scanlon, Cathy

    2013-01-01

    Investigating the heritability of brain structure may be useful in simplifying complicated genetic studies in temporal lobe epilepsy (TLE). A preliminary study is presented to determine if volume deficits of candidate brain structures present at a higher rate in unaffected siblings than controls subjects.

  1. Altered neural connectivity during response inhibition in adolescents with attention-deficit/hyperactivity disorder and their unaffected siblings

    Directory of Open Access Journals (Sweden)

    Daan van Rooij

    2015-01-01

    Discussion: Subjects with ADHD fail to integrate activation within the response inhibition network and to inhibit connectivity with task-irrelevant regions. Unaffected siblings show similar alterations only during failed stop trials, as well as unique suppression of motor areas, suggesting compensatory strategies. These findings support the role of altered functional connectivity in understanding the neurobiology and familial transmission of ADHD.

  2. Does trocar-guided tension-free vaginal mesh (Prolift) repair provoke prolapse of the unaffected compartments?

    NARCIS (Netherlands)

    Withagen, M.I.J.; Vierhout, M.E.; Milani, A.L.

    2010-01-01

    INTRODUCTION AND HYPOTHESIS: The objective of this study was to assess the effect of the tension-free vaginal mesh (Prolift) procedure on the non-treated and initially unaffected vaginal compartments. METHODS: This prospective observational cohort study involved 150 patients who underwent a Prolift

  3. High Levels of Proinflammatory Cytokines, but Not Markers of Tissue Injury, in Unaffected Intestinal Areas from Patients with IBD

    Directory of Open Access Journals (Sweden)

    Alberto J. León

    2009-01-01

    Full Text Available Intestinal alterations in IBD are triggered and maintained by an overexpression of proinflammatory cytokines. Additionally, increased immune activation has been found in the adjacent intestinal areas without displaying any apparent histological alterations, however, the regulatory environment is not well established. Biopsy specimens from patients with ulcerative colitis (UC and Crohn's disease (CD, from both affected and unaffected areas, and also from a group of colonic biopsies from healthy controls, were included in our study. Cytokines and markers of mucosal damage were analyzed by real-time PCR, and some of the results confirmed by western-blot and ELISA. Levels of IFNγ, TNFα, IL-6, IL-15, IL-18, and IL-23 were increased (above healthy controls in both affected and unaffected areas from IBD. IL-1β, IL-6, IL-12, and IL-27 were higher in affected areas compared to unaffected ones in UC but not CD. In general, a correlation was observed between mRNA levels of these cytokines and both iNOS and Granzyme B. SOCS-2 and SOCS-3 were also increased in the affected areas. In conclusion, the unaffected areas from IBD show increased levels of a restricted set of cytokines that may exert immune activating roles in these areas without being able to trigger tissue damage.

  4. Wild tomato leaf extracts for spider mite and cowpea aphid control.

    Science.gov (United States)

    Antonious, George F; Kamminga, Katherine; Snyder, John C

    2014-01-01

    Glandular trichomes on the leaves of wild tomato, L. hirsutum f. hirsutum Mull, also known as Solanum habrochaites (Solanaceae), synthesize and accumulate high levels of methyl ketones (MKs). L. hirsutum accession LA 407, having high concentration of MKs, was grown from seeds under greenhouse conditions. Four MKs (2-undecanone, 2-dodecanone, 2-tridecanone, and 2-pentadecanone) were screened for their toxicity to spider mites, Tetranychus urticae Koch and cowpea aphids, Aphis craccivora Koch. The objectives of this investigation were to: (1) develop a bioassay for testing MKs on spider mite and cowpea aphid mortality and (2) compare the efficacies of wild tomato leaf crude extracts and pure standard materials of MKs against spider mite and cowpea aphid mortality. Our results revealed that spider mites are most sensitive to 2-tridecanone (LC50 = 0.08 μmole cm(-2) of treated leaf surface) and least sensitive to 2-undecanone (LC50 = 1.5 μmole cm(-2) of treated leaf surface) 4 h after treatment. Similarly, 2-tridecanone caused greatest mortality (LC50 = 0.2 μmole cm(-2) of treated leaf surface), whereas 2-undecanone caused the lowest morality (LC50 = 0.48 μmole cm(-2) of treated surface) of cowpea aphid. We concluded that all MKs tested in this investigation are toxic to spider mites and aphids. 2-Tridecanone is more effective in killing mites and aphids compared to other MKs. Toxicity of crude extracts, prepared from the leaves of L. hirsutum accession LA 407, to spider mites and cowpea aphids revealed greater mortality compared to a combined mixture of MKs standard material (used at the same concentration as found on LA 407 leaves). This indicates that in addition to MKs, other unidentified compounds in LA 407 leaf extract also have pesticidal properties. Accordingly, leaf extracts of LA 407 could be explored in crop protection, and they might open a new area of MK formulations and discovery of biorational alternatives for pest control in agricultural fields. PMID

  5. Wild tomato leaf extracts for spider mite and cowpea aphid control.

    Science.gov (United States)

    Antonious, George F; Kamminga, Katherine; Snyder, John C

    2014-01-01

    Glandular trichomes on the leaves of wild tomato, L. hirsutum f. hirsutum Mull, also known as Solanum habrochaites (Solanaceae), synthesize and accumulate high levels of methyl ketones (MKs). L. hirsutum accession LA 407, having high concentration of MKs, was grown from seeds under greenhouse conditions. Four MKs (2-undecanone, 2-dodecanone, 2-tridecanone, and 2-pentadecanone) were screened for their toxicity to spider mites, Tetranychus urticae Koch and cowpea aphids, Aphis craccivora Koch. The objectives of this investigation were to: (1) develop a bioassay for testing MKs on spider mite and cowpea aphid mortality and (2) compare the efficacies of wild tomato leaf crude extracts and pure standard materials of MKs against spider mite and cowpea aphid mortality. Our results revealed that spider mites are most sensitive to 2-tridecanone (LC50 = 0.08 μmole cm(-2) of treated leaf surface) and least sensitive to 2-undecanone (LC50 = 1.5 μmole cm(-2) of treated leaf surface) 4 h after treatment. Similarly, 2-tridecanone caused greatest mortality (LC50 = 0.2 μmole cm(-2) of treated leaf surface), whereas 2-undecanone caused the lowest morality (LC50 = 0.48 μmole cm(-2) of treated surface) of cowpea aphid. We concluded that all MKs tested in this investigation are toxic to spider mites and aphids. 2-Tridecanone is more effective in killing mites and aphids compared to other MKs. Toxicity of crude extracts, prepared from the leaves of L. hirsutum accession LA 407, to spider mites and cowpea aphids revealed greater mortality compared to a combined mixture of MKs standard material (used at the same concentration as found on LA 407 leaves). This indicates that in addition to MKs, other unidentified compounds in LA 407 leaf extract also have pesticidal properties. Accordingly, leaf extracts of LA 407 could be explored in crop protection, and they might open a new area of MK formulations and discovery of biorational alternatives for pest control in agricultural fields.

  6. Coral Reef Ecosystem Data from the 2010-2011 Kahekili Herbivore Fisheries Management Area, West Maui, Herbivore Enhancement as a Tool for Reef Restoration Project (NODC Accession 0082869)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This research targets the Hawaii Coral Reef Initiative (HCRI) Priority Area A: Kahekili, Maui: Herbivore Fisheries Management Area (KHFMA). The project goal was to...

  7. Seasonal Changes in the Endosymbiotic Consortia of Aphids from the Genus Cinara

    Science.gov (United States)

    Martínez-Díaz, Vanesa; Latorre, Amparo; Gil, Rosario

    2016-01-01

    Buchnera aphidicola is the primary endosymbiont of aphids with which it maintains an obligate mutualistic symbiotic relationship. Insects also maintain facultative symbiotic relationships with secondary symbionts, and Serratia symbiotica is the most common in aphids. The presence of both symbionts in aphids of the subfamily Lachninae has been widely studied by our group. We examined two closely related aphids, Cinara tujafilina and C. cedri in the present study. Even though both B. aphidicola strains have similar genome sizes and gene contents, the genomes of the two S. symbiotica strains were markedly different. The SCc strain has the smallest genome known for this species, while SCt possesses a larger genome in an intermediate stage between the facultative S. symbiotica of Acyrthosiphon pisum (SAp) and the co-obligate S. symbiotica SCc. Aphids are vulnerable to high temperatures. Previous studies indicated that S. symbiotica SAp confers resistance to heat-shock stress. In order to clarify whether S. symbiotica strains from genus Cinara also play a role in heat stress protection, we performed a quantitative determination of the consortium Buchnera/Serratia from two geographically close populations, each of which belonged to the Cinara species examined, over two years in natural environments. We found no variation in the consortium from our C. cedri population, but a positive correlation between both endosymbiont densities and average daily temperatures in the C. tujafilina population. Even though S. symbiotica SCt may retain some protective role against heat stress, this does not appear to be due to the release of protective metabolites by cell lysis. PMID:27297891

  8. 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 laboratory and long-term field experiments in targeted planting

  9. Does plant trait diversity reduce the ability of herbivores to defend against predators? The plant variability-gut acclimation hypothesis.

    Science.gov (United States)

    Wetzel, William C; Thaler, Jennifer S

    2016-04-01

    Variability in plant chemistry has long been believed to suppress populations of insect herbivores by constraining herbivore resource selection behavior in ways that make herbivores more vulnerable to predation. The focus on behavior, however, overlooks the pervasive physiological effects of plant variability on herbivores. Here we propose the plant variability-gut acclimation hypothesis, which posits that plant chemical variability constrains herbivore anti-predator defenses by frequently requiring herbivores to acclimate their guts to changing plant defenses and nutrients. Gut acclimation, including changes to morphology and detoxification enzymes, requires time and nutrients, and we argue these costs will constrain how and when herbivores can mount anti-predator defenses. A consequence of this hypothesis is stronger top-down control of herbivores in heterogeneous plant populations. PMID:27436643

  10. Can plants use an entomopathogenic virus as a defense against herbivores?

    NARCIS (Netherlands)

    Munster, van M.; Janssen, A.; Clerivet, A.; Heuvel, van den J.

    2005-01-01

    It is by now well established that plants use various strategies to defend themselves against herbivores. Besides conventional weapons such as spines and stinging hairs and sophisticated chemical defenses, plants can also involve the enemies of the herbivores in their defense. It has been suggested

  11. Copper Contamination Impairs Herbivore Initiation of Seaweed Inducible Defenses and Decreases Their Effectiveness.

    Directory of Open Access Journals (Sweden)

    Alexandria M Warneke

    Full Text Available Seaweed-herbivore interactions are often mediated by environmental conditions, yet the roles of emerging anthropogenic stressors on these interactions are poorly understood. For example, chemical contaminants have unknown consequences on seaweed inducible resistance and herbivore response to these defenses despite known deleterious effects of contaminants on animal inducible defenses. Here, we investigated the effect of copper contamination on the interactions between a snail herbivore and a brown seaweed that displays inducible resistance to grazing. We examined seaweed inducible resistance and its effectiveness for organisms exposed to copper at two time points, either during induction or after herbivores had already induced seaweed defenses. Under ambient conditions, non-grazed tissues were more palatable than grazed tissues. However, copper additions negated the preference for non-grazed tissues regardless of the timing of copper exposure, suggesting that copper decreased both how herbivores initiated these inducible defenses and their subsequent effectiveness. Copper decreased stimulation of defenses, at least in part, by suppressing snail grazing pressure-the cue that turns inducible defenses on. Copper decreased effectiveness of defenses by preventing snails from preferentially consuming non-grazed seaweed. Thus, contaminants can potentially stress communities by changing seaweed-herbivore interactions mediated via inducible defenses. Given the ubiquity of seaweed inducible resistance and their potential influence on herbivores, we hypothesize that copper contamination may change the impact of these resistant traits on herbivores.

  12. Distributional congruence of mammalian herbivores in the Trans-Himalayan Mountains

    Institute of Scientific and Technical Information of China (English)

    Tsewang NAMGAIL; Sipke E.van WIEREN; Herbert H.T.PRINS

    2013-01-01

    Large-scale distribution and diversity patterns of mammalian herbivores,especially less charismatic species in alpine environments remain little understood.We studied distributional congruence of mammalian herbivores in the Trans-Himalayan region of Ladakh to see if the distributions of less prominent and smaller herbivores can be determined from those of larger and more prominent herbivores like ungulates.Using a similarity index,we assessed shared distributions of species in 20×20 km2 grid-cells in an area of about 80,000 kn2.We used the Unweighted Pair-Group Method with Arithmetic Average (UPGMA) to classify mammalian herbivores into groups with similar distributions.We then used the G-test of independence to look for statistical significance of the groups obtained.We identified six groups of mammalian herbivores with distributions more similar than expected at random.The largest group was composed of nine species whereas the other large group comprised six species.Canonical Correspondence Analysis (CCA),used to relate the groups with environmental features,showed that the largest group occurred in higher and flatter areas,while the other large group occurred in lower and steeper areas.Large herbivores like ungulates can be used as surrogate for less prominent small herbivores while identifying areas for latter's protection in the inaccessible mountainous regions of the Trans-Himalaya [Current Zoology 59 (1):116-124,2013].

  13. Attracting pollinators and avoiding herbivores: insects influence plant traits within and across years.

    Science.gov (United States)

    Buchanan, Amanda Lynn; Underwood, Nora

    2013-10-01

    Perennial plants interact with herbivores and pollinators across multiple growing seasons, and thus may respond to herbivores and pollinators both within and across years. Joint effects of herbivores and pollinators influence plant traits, but while some of the potential interactions among herbivory, pollination, plant size, and plant reproductive traits have been well studied, others are poorly understood. This is particularly true for perennial plants where effects of herbivores and pollinators may manifest across years. Here, we describe two experiments addressing the reciprocal interactions of plant traits with herbivore damage and pollination across 2 years using the perennial plant Chamerion angustifolium. We measured (1) plant responses to manipulation of damage and pollination in the year of treatment and the subsequent season, (2) damage and pollination responses to manipulation of plant size and flowering traits in the year of treatment, and (3) plant-mediated indirect interactions between herbivores and pollinators. We found that plant traits had little effect on damage and pollination, but damage and pollination affected plant traits in both the treatment year and the subsequent year. We found evidence of indirect effects between leaf herbivores and pollinators in both directions; indirect effects of pollinators on leaf herbivores have not been previously demonstrated. Our results indicate that pollen receipt results in shorter plants with fewer stems but does not change flower number, while leaf herbivory results in taller plants with fewer flowers. Together, herbivory and pollination may contribute to intermediate plant height and plants with fewer stems and flowers in our system.

  14. Top-down control of small herbivores on salt-marsh vegetation along a productivity gradient

    NARCIS (Netherlands)

    Kuijper, DPJ; Bakker, JP; Pennings, S.C.

    2005-01-01

    Exploitation theory predicts strongest plant-herbivore interactions at sites of intermediate productivity. Recent studies illustrate the importance of top-down effects by small to intermediate-sized herbivores in structuring salt-marsh communities. How long-term effects of herbivory are modified by

  15. Differences in effects of pyrrolizidine alkaloids on five generalist insect herbivore species

    NARCIS (Netherlands)

    Macel, M.; Bruinsma, M.; Dijkstra, S.M.; Ooijendijk, T.; Niemeyer, T.; Klinkhamer, P.G.L.

    2005-01-01

    The evolution of the diversity in plant secondary compounds is often thought to be driven by insect herbivores, although there is little empirical evidence for this assumption. To investigate whether generalist insect herbivores could play a role in the evolution of the diversity of related compound

  16. Do large herbivores select a diet that maximizes short-term intake rate?

    NARCIS (Netherlands)

    Wieren, van S.E.

    1996-01-01

    Using field data on diet composition, diet quality and eating behaviour of three species of herbivores (red deer, Highland cattle and Konik ponies) it was tested if herbivores select their diet according to the intake rate maximizing principle. The digestible organic matter intake rate (DOMIR) was u

  17. Contrasting patterns of herbivore and predator pressure on invasive and native plants

    NARCIS (Netherlands)

    Engelkes, T.; Wouters, B.; Bezemer, T.M.; Harvey, J.A.; Putten, van der W.H.

    2012-01-01

    Invasive non-native plant species often harbor fewer herbivorous insects than related native plant species. However, little is known about how herbivorous insects on non-native plants are exposed to carnivorous insects, and even less is known on plants that have recently expanded their ranges within

  18. Herbivory in global climate change research: direct effects of rising temperature on insect herbivores

    NARCIS (Netherlands)

    Bale, J.S.; Masters, G.J.; Hodkinson, I.D.; Awmack, C.; Bezemer, T.M.; Brown, V.K.; Butterfield, J.; Buse, A.; Coulson, J.C.; Farrar, J.; Good, J.E.G.; Harrington, R.; Hartley, S.; Jones, T.H.; Lindroth, R.L.; Press, M.C.; Symrnioudis, I.; Watt, A.D.; Whittaker, J.B.

    2002-01-01

    This review examines the direct effects of climate change on insect herbivores. Temperature is identified as the dominant abiotic factor directly affecting herbivorous insects. There is little evidence of any direct effects Of CO2 or UVB. Direct impacts of precipitation have been largely neglected i

  19. The evolutionary context for herbivore-induced plant volatiles: beyond the ‘cry for help’

    NARCIS (Netherlands)

    Dicke, M.; Baldwin, I.T.

    2010-01-01

    Attacks by herbivores elicit changes in the bouquet of volatiles released by plants. These herbivore-induced plant volatiles (HIPVs) have been interpreted as being indirect defenses. However, given that no studies have yet investigated whether HIPVs benefit the fitness of a plant, their defensive fu

  20. Landscape-scale analyses suggest both nutrient and antipredator advantages to Serengeti herbivore hotspots

    NARCIS (Netherlands)

    Anderson, T. Michael; Hopcraft, J. Grant C.; Eby, Stephanie; Ritchie, Mark; Grace, James B.; Olff, Han; Young, T.P.

    2010-01-01

    Mechanistic explanations of herbivore spatial distribution have focused largely on either resource-related (bottom-up) or predation-related (top-down) factors. We studied direct and indirect influences on the spatial distributions of Serengeti herbivore hotspots, defined as temporally stable areas i

  1. Challenges in the nutrition and management of herbivores in the temperate zone

    NARCIS (Netherlands)

    Vuuren, van A.M.; Chilibroste, P.

    2013-01-01

    The expected higher global demand for animal proteins and the competition for starch and sugars between food, fuel and feed seem to favour herbivores that convert solar energy captured in fibrous plants into animal products. However, the required higher production level of herbivores questions the s

  2. Plant chemical defense against herbivores and pathogens: generalized defense or trade-offs?

    NARCIS (Netherlands)

    Biere, A.; Marak, H.B.; Van Damme, J.M.M.

    2004-01-01

    Plants are often attacked by multiple enemies, including pathogens and herbivores. While many plant secondary metabolites show specific effects toward either pathogens or herbivores, some can affect the performance of both these groups of natural enemies and are considered to be generalized defense

  3. Plant defense against herbivorous pests: exploiting resistance and tolerance traits for sustainable crop protection

    Directory of Open Access Journals (Sweden)

    Carolyn Mitchell

    2016-07-01

    Full Text Available Interactions between plants and insect herbivores are important determinants of plant productivity in managed and natural vegetation. In response to attack, plants have evolved a range of defenses to reduce the threat of injury and loss of productivity. Crop losses from damage caused by arthropod pests can exceed 15% annually. Crop domestication and selection for improved yield and quality can alter the defensive capability of the crop, increasing reliance on artificial crop protection. Sustainable agriculture, however, depends on reduced chemical inputs. There is an urgent need, therefore, to identify plant defensive traits for crop improvement. Plant defense can be divided into resistance and tolerance strategies. Plant traits that confer herbivore resistance typically prevent or reduce herbivore damage through expression of traits that deter pests from settling, attaching to surfaces, feeding and reproducing, or that reduce palatability. Plant tolerance of herbivory involves expression of traits that limit the negative impact of herbivore damage on productivity and yield. Identifying the defensive traits expressed by plants to deter herbivores or limit herbivore damage, and understanding the underlying defense mechanisms, is crucial for crop scientists to exploit plant defensive traits in crop breeding. In this review, we assess the traits and mechanisms underpinning herbivore resistance and tolerance, and conclude that physical defense traits, plant vigor and herbivore-induced plant volatiles show considerable utility in pest control, along with mixed species crops. We highlight emerging approaches for accelerating the identification of plant defensive traits and facilitating their deployment to improve the future sustainability of crop protection.

  4. Plant Defense against Herbivorous Pests: Exploiting Resistance and Tolerance Traits for Sustainable Crop Protection.

    Science.gov (United States)

    Mitchell, Carolyn; Brennan, Rex M; Graham, Julie; Karley, Alison J

    2016-01-01

    Interactions between plants and insect herbivores are important determinants of plant productivity in managed and natural vegetation. In response to attack, plants have evolved a range of defenses to reduce the threat of injury and loss of productivity. Crop losses from damage caused by arthropod pests can exceed 15% annually. Crop domestication and selection for improved yield and quality can alter the defensive capability of the crop, increasing reliance on artificial crop protection. Sustainable agriculture, however, depends on reduced chemical inputs. There is an urgent need, therefore, to identify plant defensive traits for crop improvement. Plant defense can be divided into resistance and tolerance strategies. Plant traits that confer herbivore resistance typically prevent or reduce herbivore damage through expression of traits that deter pests from settling, attaching to surfaces, feeding and reproducing, or that reduce palatability. Plant tolerance of herbivory involves expression of traits that limit the negative impact of herbivore damage on productivity and yield. Identifying the defensive traits expressed by plants to deter herbivores or limit herbivore damage, and understanding the underlying defense mechanisms, is crucial for crop scientists to exploit plant defensive traits in crop breeding. In this review, we assess the traits and mechanisms underpinning herbivore resistance and tolerance, and conclude that physical defense traits, plant vigor and herbivore-induced plant volatiles show considerable utility in pest control, along with mixed species crops. We highlight emerging approaches for accelerating the identification of plant defensive traits and facilitating their deployment to improve the future sustainability of crop protection.

  5. Integrating Studies on Plant-Pollinator and Plant-Herbivore Interactions

    NARCIS (Netherlands)

    Lucas-Barbosa, Dani

    2016-01-01

    Research on herbivore-induced plant defence and research on pollination ecology have had a long history of separation. Plant reproduction of most angiosperm species is mediated by pollinators, and the effects of herbivore-induced plant defences on pollinator behaviour have been largely neglected.

  6. Among rodents and rhinos: interplay between small mammals and large herbivores in a South African savanna

    NARCIS (Netherlands)

    Hagenah, N.

    2006-01-01

    Keywords:African savanna, biodiversity, Dichrostachys cinerea , different-sized herbivores, fire, herbivore interactions, murid rodents, spatial heterogeneity

    Mankind has cause

  7. Herbivore impact on moss depth, soil temperature and arctic plant growth

    NARCIS (Netherlands)

    van der Wal, R; Loonen, MJJE

    2001-01-01

    We provide evidence for a mechanism by which herbivores may influence plant abundance in arctic ecosystems, These systems are commonly dominated by mosses, the thickness of which influences the amount of heat reaching the soil surface. Herbivores can reduce the thickness of the moss layer by means o

  8. Plant Defense against Herbivorous Pests: Exploiting Resistance and Tolerance Traits for Sustainable Crop Protection

    Science.gov (United States)

    Mitchell, Carolyn; Brennan, Rex M.; Graham, Julie; Karley, Alison J.

    2016-01-01

    Interactions between plants and insect herbivores are important determinants of plant productivity in managed and natural vegetation. In response to attack, plants have evolved a range of defenses to reduce the threat of injury and loss of productivity. Crop losses from damage caused by arthropod pests can exceed 15% annually. Crop domestication and selection for improved yield and quality can alter the defensive capability of the crop, increasing reliance on artificial crop protection. Sustainable agriculture, however, depends on reduced chemical inputs. There is an urgent need, therefore, to identify plant defensive traits for crop improvement. Plant defense can be divided into resistance and tolerance strategies. Plant traits that confer herbivore resistance typically prevent or reduce herbivore damage through expression of traits that deter pests from settling, attaching to surfaces, feeding and reproducing, or that reduce palatability. Plant tolerance of herbivory involves expression of traits that limit the negative impact of herbivore damage on productivity and yield. Identifying the defensive traits expressed by plants to deter herbivores or limit herbivore damage, and understanding the underlying defense mechanisms, is crucial for crop scientists to exploit plant defensive traits in crop breeding. In this review, we assess the traits and mechanisms underpinning herbivore resistance and tolerance, and conclude that physical defense traits, plant vigor and herbivore-induced plant volatiles show considerable utility in pest control, along with mixed species crops. We highlight emerging approaches for accelerating the identification of plant defensive traits and facilitating their deployment to improve the future sustainability of crop protection. PMID:27524994

  9. Plant Volatiles Induced by Herbivore Egg Deposition Affect Insects of Different Trophic Levels

    NARCIS (Netherlands)

    Fatouros, N.E.; Lucas-Barbosa, D.; Weldegergis, B.T.; Pashalidou, F.G.; Loon, van J.J.A.; Dicke, M.; Harvey, J.A.; Gols, R.; Huigens, M.E.

    2012-01-01

    Plants release volatiles induced by herbivore feeding that may affect the diversity and composition of plant-associated arthropod communities. However, the specificity and role of plant volatiles induced during the early phase of attack, i.e. egg deposition by herbivorous insects, and their conseque

  10. Troublesome toxins: Time to re-think plant-herbivore interactions in vertebrate ecology

    Science.gov (United States)

    Swihart, R.K.; DeAngelis, D.L.; Feng, Z.; Bryant, J.P.

    2009-01-01

    Earlier models of plant-herbivore interactions relied on forms of functional response that related rates of ingestion by herbivores to mechanical or physical attributes such as bite size and rate. These models fail to predict a growing number of findings that implicate chemical toxins as important determinants of plant-herbivore dynamics. Specifically, considerable evidence suggests that toxins set upper limits on food intake for many species of herbivorous vertebrates. Herbivores feeding on toxin-containing plants must avoid saturating their detoxification systems, which often occurs before ingestion rates are limited by mechanical handling of food items. In light of the importance of plant toxins, a new approach is needed to link herbivores to their food base. We discuss necessary features of such an approach, note recent advances in herbivore functional response models that incorporate effects of plant toxins, and mention predictions that are consistent with observations in natural systems. Future ecological studies will need to address explicitly the importance of plant toxins in shaping plant and herbivore communities.

  11. Confounded winter and spring phenoclimatology on large herbivore ranges

    Science.gov (United States)

    Christianson, David; Klaver, Robert W.; Middleton, Arthur; Kauffman, Matthew

    2013-01-01

    Annual variation in winter severity and growing season vegetation dynamics appear to influence the demography of temperate herbivores but parsing winter from spring effects requires independent metrics of environmental conditions specific to each season. We tested for independence in annual variation amongst four common metrics used to describe winter severity and early growing season vegetation dynamics across the entire spatial distribution of elk (Cervus elaphus) in Wyoming from 1989 to 2006. Winter conditions and early growing season dynamics were correlated in a specific way. Winters with snow cover that ended early tended to be followed by early, but slow, rises in the normalized difference vegetation index (NDVI), while long winters with extended periods of snow cover were often followed by late and rapid rises in NDVI. Across the 35 elk ranges, 0.4–86.8 % of the variation in the rate of increase in NDVI’s in spring was explained by the date snow cover disappeared from SNOTEL stations. Because phenoclimatological metrics are correlated across seasons and shifting due to climate change, identifying environmental constraints on herbivore fitness, particularly migratory species, is more difficult than previously recognized.

  12. Cycads: their evolution, toxins, herbivores and insect pollinators

    Science.gov (United States)

    Schneider, Dietrich; Wink, Michael; Sporer, Frank; Lounibos, Philip

    2002-06-01

    Palaeobiological evidence indicates that gymnosperms were wind-pollinated and that insect pollination began in angiosperms in the Lower Cretaceous (ca. 135 mya) leading to close associations between higher plants and their pollinators. Cycads, which were widespread and pervasive throughout the Mesozoic (250-65 mya) are among the most primitive living seed-plants found today. Because pollination by beetles and by thrips has now been detected in several modern cycads, it is attractive to speculate that some insects and cycads had already developed similar mutualistic interactions in the Triassic (250-205 mya), long before the advent of angiosperms. We also draw attention to another key factor in this insect-plant relationship, namely secondary, defensive plant substances which must always have controlled interspecific interactions. Cycads mainly produce toxic azoglucosides and neurotoxic non-protein amino acids (e.g. BMAA), which apparently are crucial elements in the development and maintenance of mutualism (pollination) and parasitism (herbivory) by cycad-linked herbivores. We now add new results on the uptake and storage of the main toxin, cycasin, of the Mexican cycad Zamia furfuracea by its pollinator, the weevil Rhopalotria mollis, and by a specialist herbivore of Zamia integrifolia, the aposematic Atala butterfly Eumaeus atala.

  13. Where do herbivore-induced plant volatiles go?

    Directory of Open Access Journals (Sweden)

    Jarmo K. Holopainen

    2013-06-01

    Full Text Available Herbivore induced plant volatiles (HIPV are specific volatile organic compounds (VOC that a plant produces in response to herbivory. Some HIPVs are only produced after damage, while others are also produced by intact plants, but in lower quantities. Among the known functions of HIPVs are within plant volatile signalling to activate systemic plant defences, the priming and activation of defences in neighbouring plants and the attraction of natural enemies of herbivores. When released into the atmosphere a plant’s control over the produced compounds ends. However, many of the HIPVs are highly reactive with atmospheric oxidants and their atmospheric life times could be relatively short, often only a few minutes. We summarise the potential ecological and atmospheric processes that involve the reaction products of HIPVs in their gaseous, liquid and solid secondary organic aerosol (SOA forms, both in the atmosphere and after deposition on plant surfaces. A potential negative feedback loop, based on the reactions forming SOA from HIPV and the associated stimulation of sun screening cloud formation is presented. This hypothesis is based on recent field surveys in the geographical areas facing greatest degree of global warming and insect outbreaks. Furthermore, we discuss how these processes could benefit the individual plant or conspecifics that originally released the HIPVs into the atmosphere. Further ecological studies should aim to elucidate the possible reasons for biosynthesis of short-lived volatile compounds to have evolved as a response to external biotic damage to plants.

  14. Niche Segregation between Wild and Domestic Herbivores in Chilean Patagonia

    Science.gov (United States)

    Iranzo, Esperanza C.; Traba, Juan; Acebes, Pablo; González, Benito A.; Mata, Cristina; Estades, Cristián F.; Malo, Juan E.

    2013-01-01

    Competition arises when two co-occuring species share a limiting resource. Potential for competition is higher when species have coexisted for a short time, as it is the case for herbivores and livestock introduced in natural systems. Sheep, introduced in the late 19th century in Patagonia, bear a great resemblance in size and diet to the guanaco, the main native herbivore in Patagonia. In such circumstances, it could be expected that the two species compete and one of them could be displaced. We investigated spatial overlap and habitat selection by coexisting sheep and guanaco in winter and in summer. Additionally, we studied habitat selection of the guanaco in a control situation free from sheep, both in summer and winter. We also determined overlap between species in areas with different intensity of use (named preferred and marginal areas) in order to further detect the potential level of competition in the case of overlapping. Guanaco and sheep showed significantly different habitat preferences through all seasons, in spite of their spatial overlap at landscape scale. Additionally, the habitat used by guanaco was similar regardless of the presence or absence of livestock, which further indicates that sheep is not displacing guanaco where they coexist. These results suggest that habitat segregation between guanaco and sheep is due to a differential habitat selection and not to a competitive displacement process. Therefore, the potential for competition is considered low, contrary to what has been previously observed, although this could be a density-dependent result. PMID:23555656

  15. Niche segregation between wild and domestic herbivores in Chilean Patagonia.

    Directory of Open Access Journals (Sweden)

    Esperanza C Iranzo

    Full Text Available Competition arises when two co-occuring species share a limiting resource. Potential for competition is higher when species have coexisted for a short time, as it is the case for herbivores and livestock introduced in natural systems. Sheep, introduced in the late 19(th century in Patagonia, bear a great resemblance in size and diet to the guanaco, the main native herbivore in Patagonia. In such circumstances, it could be expected that the two species compete and one of them could be displaced. We investigated spatial overlap and habitat selection by coexisting sheep and guanaco in winter and in summer. Additionally, we studied habitat selection of the guanaco in a control situation free from sheep, both in summer and winter. We also determined overlap between species in areas with different intensity of use (named preferred and marginal areas in order to further detect the potential level of competition in the case of overlapping. Guanaco and sheep showed significantly different habitat preferences through all seasons, in spite of their spatial overlap at landscape scale. Additionally, the habitat used by guanaco was similar regardless of the presence or absence of livestock, which further indicates that sheep is not displacing guanaco where they coexist. These results suggest that habitat segregation between guanaco and sheep is due to a differential habitat selection and not to a competitive displacement process. Therefore, the potential for competition is considered low, contrary to what has been previously observed, although this could be a density-dependent result.

  16. Effects of termites (Macrotermes) and large Herbivores on exotic and native tre species in Lake Mburo National Park, Uganda

    OpenAIRE

    Jessen, Malin

    2014-01-01

    Both termites and large herbivores are important to ecological processes in the African savannah. Termites and large herbivores contribute to spatial heterogeneity in distinct ways. Large herbivores facilitate tree regeneration through feeding preferences, thereby causing reduced competition between grasses and woody plants. Herbivores also act as predators on tree seedlings, thus reducing seedling growth and survival. Termites of the genus Macrotermes are considered pests in plantation sites...

  17. Virus infection decreases the attractiveness of white clover plants for a non-vectoring herbivore

    DEFF Research Database (Denmark)

    van Mölken, Tamara; Caluwe, Hannie de; Hordijk, Cornelis A.;

    2012-01-01

    Plant pathogens and insect herbivores are prone to share hosts under natural conditions. Consequently, pathogen-induced changes in the host plant can affect herbivory, and vice versa. Even though plant viruses are ubiquitous in the field, little is known about plant-mediated interactions between...... viruses and non-vectoring herbivores. We investigated the effects of virus infection on subsequent infestation by a non-vectoring herbivore in a natural genotype of Trifolium repens (white clover). We tested whether infection with White clover mosaic virus (WClMV) alters (1) the effects of fungus gnat....... This suggests that virus infections may contribute to protecting their hosts by decreasing herbivore infestation rates. Consequently, it is conceivable that viruses play a more beneficial role in plant-herbivore interactions than generally thought....

  18. Anomalous dependence of population growth on the birth rate in the plant-herbivore system

    Energy Technology Data Exchange (ETDEWEB)

    Cui, Xue M. [Chungbuk National University, Cheongju (Korea, Republic of); Yanbian University, Yanji (China); Han, Seung K.; Chung, Jean S. [Chungbuk National University, Cheongju (Korea, Republic of)

    2010-12-15

    We performed a simulation of the two-species plant-herbivore system by using the agent-based NetLogo program and constructed a dynamic model of populations consistent with the simulation results. The dynamic model is a three-dimensional system including the mean energy of the herbivore in addition to two variables denoting the populations of plants and herbivores. A steady-state analysis of the dynamic model shows that the dependence of the herbivore population on the birth and the death rates observed from the agent model is consistent with the prediction of the dynamic model. Especially, the anomalous dependence of the herbivore population on the birth rate, where the population decreases with the birth rate for small death rate, is consistently explained by a phase plane analysis of the dynamic model.

  19. Eco-evolutionary dynamics of plant-herbivore communities: incorporating plant phenotypic plasticity.

    Science.gov (United States)

    Ohgushi, Takayuki

    2016-04-01

    The interplay between evolution and ecological communities is critical for the integration of different levels of biological organization. Recent work has begun to unveil the importance of plant phenotypic plasticity and plant-herbivore (co)evolution to link plant evolution and associated insect communities. Specifically, herbivore-induced plant traits (i.e., plastic phenotypes) have significant effects on the structure and diversity of herbivore communities, which can in turn promote the evolution of not only the focal plant but also insect community members. Here, I will provide a conceptual framework on the eco-evolutionary dynamics of plant-herbivore communities to understand how biological organizations are integrated in plant-insect interactions. Research on eco-evolutionary dynamics of plant-herbivore communities will undoubtedly enrich understanding of a wide range of plant-insect interactions. PMID:27436645

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

    Science.gov (United States)

    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). Virtually al...

  1. 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

  2. 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....

  3. 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....... rapae as a biocontrol agent of Brevicoryne brassicae at different temperatures.......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...

  4. QTL Mapping by SLAF-seq and Expression Analysis of Candidate Genes for Aphid Resistance in Cucumber.

    Science.gov (United States)

    Liang, Danna; Chen, Minyang; Qi, Xiaohua; Xu, Qiang; Zhou, Fucai; Chen, Xuehao

    2016-01-01

    Cucumber, a very important vegetable crop worldwide, is easily damaged by pests. Aphid is one of the most serious cucumber pests and frequently cause severe damage to commercially produced crops. Understanding the genetic mechanisms underlying pest resistance is important for aphid-resistant cucumber varieties breeding. In this study, two parental cucumber lines, JY30 (aphid susceptible) and EP6392 (aphid resistant), and pools of resistant and susceptible (n = 50 each) plants from 1000 F2 individuals derived from crossing JY30 with EP6392, were used to detect genomic regions associated with aphid resistance in cucumbers. The analysis was performed using specific length amplified fragment sequencing (SLAF-seq), bulked segregant analysis (BSA), and single nucleotide polymorphism index (SNP-index) methods. A main effect QTL (quantitative trait locus) of 0.31 Mb on Chr5, including 43 genes, was identified by association analysis. Sixteen of the 43 genes were identified as potentially associated with aphid resistance through gene annotation analysis. The effect of aphid infestation on the expression of these candidate genes screened by SLAF-seq was investigated in EP6392 plants by qRT-PCR. The results indicated that seven genes including encoding transcription factor MYB59-like (Csa5M641610.1), auxin transport protein BIG-like (Csa5M642140.1), F-box/kelch-repeat protein At5g15710-like (Csa5M642160.1), transcription factor HBP-1a-like (Csa5M642710.1), beta-glucan-binding protein (Csa5M643380.1), endo-1,3(4)-beta-glucanase 1-like (Csa5M643880.1), and proline-rich receptor-like protein kinase PERK10-like (Csa5M643900.1), out of the 16 genes were down regulated after aphid infestation, whereas 5 genes including encoding probable leucine-rich repeat (LRR) receptor-like serine/threonine-protein kinase At5g15730-like (Csa5M642150.1), Stress-induced protein KIN2 (Csa5M643240.1 and Csa5M643260.1), F-box family protein (Csa5M643280.1), F-box/kelch-repeat protein (Csa5M643290

  5. QTL Mapping by SLAF-seq and Expression Analysis of Candidate Genes for Aphid Resistance in Cucumber

    Directory of Open Access Journals (Sweden)

    Danna Liang

    2016-07-01

    Full Text Available Cucumber, a very important vegetable crop worldwide, is easily damaged by pests. Aphid is one of the most serious cucumber pests and frequently cause severe damage to commercially produced crops. Understanding the genetic mechanisms underlying pest resistance is important for aphid-resistant cucumber varieties breeding. In this study, two parental cucumber lines, JY30 (aphid susceptible and EP6392 (aphid resistant, and pools of resistant and susceptible (n = 50 each plants from 1000 F2 individuals derived from crossing JY30 with EP6392, were used to detect genomic regions associated with aphid resistance in cucumbers. The analysis was performed using specific length amplified fragment sequencing (SLAF-seq, bulked segregant analysis (BSA and single nucleotide polymorphism index (SNP-index methods. A main effect QTL (quantitative trait locus of 0.31 Mb on Chr5, including 43 genes, was identified by association analysis. Sixteen of the 43 genes were identified as potentially associated with aphid resistance through gene annotation analysis. The effect of aphid infestation on the expression of these candidate genes screened by SLAF-seq was investigated in EP6392 plants by qRT-PCR. The results indicated that 7 genes including encoding transcription factor MYB59-like (Csa5M641610.1, auxin transport protein BIG-like (Csa5M642140.1, F-box/kelch-repeat protein At5g15710-like (Csa5M642160.1, transcription factor HBP-1a-like (Csa5M642710.1, beta-glucan-binding protein (Csa5M643380.1, endo-1,3(4-beta-glucanase 1-like (Csa5M643880.1, and proline-rich receptor-like protein kinase PERK10-like (Csa5M643900.1, out of the 16 genes were down regulated after aphid infestation, whereas 5 genes including encoding probable leucine-rich repeat receptor-like serine/threonine-protein kinase At5g15730-like (Csa5M642150.1, Stress-induced protein KIN2 (Csa5M643240.1 and Csa5M643260.1, F-box family protein (Csa5M643280.1, F-box/kelch-repeat protein (Csa5M643290.1, were up

  6. A reinvestigation provides no evidence for sugar residues on structural proteins of poleroviruses and argues against a role for glycosylation of virus structural proteins in aphid transmission.

    Science.gov (United States)

    Revollon, S; Strub, J M; Fitchette, A-C; Wiss, L; Gomord, V; Van Dorsselaer, A; Brault, V

    2010-07-01

    Poleroviruses are strictly transmitted by aphids. Glycosylation of Turnip yellows virus (TuYV) was previously reported and this modification was supposed to be required for aphid transmission. Using different approaches based on (i) a lectin-binding assay, (ii) use of specific complex glycan antibodies and (iii) mass spectrometry, we found no evidence that the structural proteins of TuYV and Cucurbit aphid-borne yellow virus (CABYV) carry glycan residues. Moreover, mutation of each of the four potential N-glycosylation sites of the structural protein sequences of CABYV indicated that, unless more than one site on the structural protein is glycosylated, N-glycosylation is not involved in aphid transmission. These results did not corroborate the previous hypothesis for the role of glycosylation in aphid transmission. They, however, revealed the presence of a glycosylated plant protein in purified polerovirus suspensions, whose function in aphid transmission should be further investigated. PMID:20416918

  7. The spatial distribution of African savannah herbivores: species associations and habitat occupancy in a landscape context.

    Science.gov (United States)

    Anderson, T Michael; White, Staci; Davis, Bryant; Erhardt, Rob; Palmer, Meredith; Swanson, Alexandra; Kosmala, Margaret; Packer, Craig

    2016-09-19

    Herbivores play an important role in determining the structure and function of tropical savannahs. Here, we (i) outline a framework for how interactions among large mammalian herbivores, carnivores and environmental variation influence herbivore habitat occupancy in tropical savannahs. We then (ii) use a Bayesian hierarchical model to analyse camera trap data to quantify spatial patterns of habitat occupancy for lions and eight common ungulates of varying body size across an approximately 1100 km(2) landscape in the Serengeti ecosystem. Our results reveal strong positive associations among herbivores at the scale of the entire landscape. Lions were positively associated with migratory ungulates but negatively associated with residents. Herbivore habitat occupancy differed with body size and migratory strategy: large-bodied migrants, at less risk of predation and able to tolerate lower quality food, were associated with high NDVI, while smaller residents, constrained to higher quality forage, avoided these areas. Small herbivores were strongly associated with fires, likely due to the subsequent high-quality regrowth, while larger herbivores avoided burned areas. Body mass was strongly related to herbivore habitat use, with larger species more strongly associated with riverine and woodlands than smaller species. Large-bodied migrants displayed diffuse habitat occupancy, whereas smaller species demonstrated fine-scale occupancy reflecting use of smaller patches of high-quality habitat. Our results demonstrate the emergence of strong positive spatial associations among a diverse group of savannah herbivores, while highlighting species-specific habitat selection strongly determined by herbivore body size.This article is part of the themed issue 'Tropical grassy biomes: linking ecology, human use and conservation'. PMID:27502379

  8. Herbivore trampling as an alternative pathway for explaining differences in nitrogen mineralization in moist grasslands.

    Science.gov (United States)

    Schrama, Maarten; Heijning, Pieter; Bakker, Jan P; van Wijnen, Harm J; Berg, Matty P; Olff, Han

    2013-05-01

    Studies addressing the role of large herbivores on nitrogen cycling in grasslands have suggested that the direction of effects depends on soil fertility. Via selection for high quality plant species and input of dung and urine, large herbivores have been shown to speed up nitrogen cycling in fertile grassland soils while slowing down nitrogen cycling in unfertile soils. However, recent studies show that large herbivores can reduce nitrogen mineralization in some temperate fertile soils, but not in others. To explain this, we hypothesize that large herbivores can reduce nitrogen mineralization in loamy or clay soils through soil compaction, but not in sandy soils. Especially under wet conditions, strong compaction in clay soils can lead to periods of soil anoxia, which reduces decomposition of soil organic matter and, hence, N mineralization. In this study, we use a long-term (37-year) field experiment on a salt marsh to investigate the hypothesis that the effect of large herbivores on nitrogen mineralization depends on soil texture. Our results confirm that the presence of large herbivores decreased nitrogen mineralization rate in a clay soil, but not in a sandy soil. By comparing a hand-mown treatment with a herbivore-grazed treatment, we show that these differences can be attributed to herbivore-induced changes in soil physical properties rather than to above-ground biomass removal. On clay soil, we find that large herbivores increase the soil water-filled porosity, induce more negative soil redox potentials, reduce soil macrofauna abundance, and reduce decomposition activity. On sandy soil, we observe no changes in these variables in response to grazing. We conclude that effects of large herbivores on nitrogen mineralization cannot be understood without taking soil texture, soil moisture, and feedbacks through soil macrofauna into account. PMID:23271034

  9. Cross-site comparison of herbivore impact on nitrogen availability in grasslands: the role of plant nitrogen concentration

    NARCIS (Netherlands)

    Bakker, E.S.; Knops, J.M.H.; Milchunas, D.G.; Ritchie, M.E.; Olff, H.

    2009-01-01

    Herbivores may influence the nitrogen (N) recycling rates and consequently increase or decrease the productivity of grasslands. Plant N concentration emerged as a critical parameter to explain herbivore effects from several conceptual models, which predict that herbivores decrease soil N availabilit

  10. Information use by the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae), a specialised natural enemy of herbivorous spider mites

    NARCIS (Netherlands)

    Boer, de J.G.; Dicke, M.

    2005-01-01

    Plants can respond to infestation by herbivores with the emission of specific herbivore-induced plant volatiles. Many carnivorous arthropods that feed on herbivorous prey use these volatiles to locate their prey. Despite the growing amount of research papers on the interactions in tritrophic systems

  11. Spatial organization of the glucosinolate-myrosinase system in brassica specialist aphids is similar to that of the host plant.

    OpenAIRE

    Bridges, Matthew; Jones, Alexandra M. E.; Bones, Atle M.; Hodgson, Chris; Cole, Rosemary; Bartlet, Elspeth; Wallsgrove, Roger; Karapapa, Vassiliki K; Watts, Nigel; Rossiter, John T.

    2002-01-01

    Secondary metabolites are important in plant defence against pests and diseases. Similarly, insects can use plant secondary metabolites in defence and, in some cases, synthesize their own products. The paper describes how two specialist brassica feeders, Brevicoryne brassicae (cabbage aphid) and Lipaphis erysimi (turnip aphid) can sequester glucosinolates (thioglucosides) from their host plants, yet avoid the generation of toxic degradation products by compartmentalizing myrosinase (thiogluco...

  12. 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. PMID:27178208

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

    OpenAIRE

    Rausch, Michael A.; Nanasaheb P Chougule; Deist, Benjamin R.; Bonning, Bryony C.

    2016-01-01

    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 cathep...

  14. Effects of autumn kaolin treatments on the rosy apple aphid Dysaphis planaginea (Pass.) and possible modes of action.

    OpenAIRE

    Bürgel, K.; Daniel, Claudia; Wyss, Eric

    2005-01-01

    Autumn applications of the repellent processed-kaolin particle film (Surround ® WP) might be an alternative to the insecticides commonly used in spring to control the rosy apple aphid, Dysaphis plantaginea (Pass.) (Hom., Aphididae). To assess the mode of action and the impact of kaolin on autumn forms of D. plantaginea, trials were conducted in field cages and in open-fields in autumn 2003. Choice and no-choice experiments in field cages showed that winged aphids landed in significantly lower...

  15. Development and characterization of Brassica juncea – fruticulosa introgression lines exhibiting resistance to mustard aphid (Lipaphis erysimi Kalt

    Directory of Open Access Journals (Sweden)

    Atri Chhaya

    2012-11-01

    Full Text Available Abstract Background Mustard aphid is a major pest of Brassica oilseeds. No source for aphid resistance is presently available in Brassica juncea . A wild crucifer, Brassica fruticulosa is known to be resistant to mustard aphid. An artificially synthesized amphiploid, AD-4 (B. fruticulosa × B. rapa var. brown sarson was developed for use as a bridge species to transfer fruticulosa resistance to B. juncea. Using the selfed backcross we could select a large number of lines with resistance to mustard aphid. This paper reports cytogenetic stability of introgression lines, molecular evidence for alien introgression and their reaction to mustard aphid infestation. Results Majority of introgression lines had expected euploid chromosome number(2n= 36, showed normal meiosis and high pollen grain fertility. Well-distributed and transferable simple-sequence repeats (SSR markers for all the 18 B. juncea chromosomes helped to characterize introgression events. Average proportions of recipient and donor genome in the substitution lines were 49.72 and 35.06%, respectively. Minimum alien parent genome presence (27.29% was observed in the introgression line, Ad3K-280 . Introgressed genotypes also varied for their resistance responses to mustard aphid infestations under artificial release conditions for two continuous seasons. Some of the test genotypes showed consistent resistant reaction. Conclusions B.juncea-fruticulosa introgression set may prove to be a very powerful breeding tool for aphid resistance related QTL/gene discovery and fine mapping of the desired genes/QTLs to facilitate marker assisted transfer of identified gene(s for mustard aphid resistance in the background of commercial mustard genotypes.

  16. Localization, Concentration, and Transmission Efficiency of Banana bunchy top virus in Four Asexual Lineages of Pentalonia aphids

    OpenAIRE

    Alberto Bressan; Shizu Watanabe; April M. Greenwell

    2013-01-01

    Banana bunchy top virus (BBTV) is the most destructive pathogenic virus of banana plants worldwide. The virus is transmitted in a circulative non-propagative manner by the banana aphid, Pentalonia nigronervosa Coquerel. In this work, we examined the localization, accumulation, and transmission efficiency of BBTV in four laboratory-established lineages of Pentalonia aphids derived from four different host plants: taro (Colocasia esculenta), heliconia (Heliconia spp.), red ginger (Alpinia purpu...

  17. Alternation in F-wave parameters of median nerve from unaffected extremity in stroke patients with hemiplegia under dynamic state

    Institute of Scientific and Technical Information of China (English)

    Hang Zhao; Yong Lin; Wenhua Qi; Shuping Yin; Jiachun Feng

    2006-01-01

    BACKGROUND: For many years, the extremities of stroke patients are divided into affected side and unaffected side according to clinical symptoms and body signs. Moreover, previous rehabilitation function training is developed simply aiming to the dysfunction manifested by unaffected extremity. Problems of unaffected extremity are always ignored, such as left- and right- side connection dysfunction, abnormal muscular tension of unaffected side and so on.OBJECTIVE: To observe neurophysiological change characteristics of unaffected extremity of stroke patients with hemiplegia by electromyographical method.DESIGN: Case-control observation.SETTING: First Hospital, Jilin University.PARTICIPANTS: Eighty stroke patients with hemiplegia confirmed by skull CT or MRI, who firstly hospitalized in the Department of Neurology, First Hospital, Jilin University between July 2004 and March 2005, were retrieved. They were scored > 8 points in Glasgow Coma Scale and had stable vital sign. Nineteen normal persons who received healthy examination in the clinic were involved in normal control group. Following the classification criteria of Brunnstrom's Recovery Stages of Stroke (BRSS), 80 stroke patients with hemiplegia were assigned into 3 groups: BRSS Ⅰ -Ⅱ group (n =36), BRSS Ⅲ-Ⅳ group (n =23) and BRSSⅤ-Ⅵ (n=21).METHODS: F-wave parameters of median nerve of unaffected extremity were detected by electromyographical technique. The recording electrode (muscular belly of abductor pollicis brevis) and reference electrode (first finger bone) were connected with grounding electrode. Stimulating electrode was placed in the median part of wrist joint with stimulation intensity of 130% that of threshold stimulation, stimulation frequency of 2 Hz, current pulse width of 0.2 ms, time course of 5 ms and sensitivity of 2 mV. The F-wave of median nerve of affected extremity under the resting stage (static status) and that of unaffected extremity under the maximum resistant contracted

  18. Effect of sowing date and straw mulch on virus incidence and aphid infestation in organic faba-beans (Vicia faba L.)

    OpenAIRE

    Saucke, H; Juergens, M.; Döring, Th. F.; Lesemann, D.E.; Fittje, S.; Vetten, H.-J.

    2009-01-01

    The effect of sowing date on aphid infestation and the incidence of aphid-transmitted viruses were investigated in organically managed, small-scale field experiments with two faba bean cultivars over 3 years (2002–04). As an additional factor, strawmulchwas applied in 2 of the 3 years shortly before the start of vector activity in May. Virus incidence was determined using enzyme-linked immunosorbent assay and immunoelectron microscopy. Aphid flight activity was monitored using standard yellow...

  19. Interactions between a luteovirus and the GroEL chaperonin protein of the symbiotic bacterium Buchnera aphidicola of aphids.

    Science.gov (United States)

    Bouvaine, Sophie; Boonham, Neil; Douglas, Angela E

    2011-06-01

    Luteoviruses and poleroviruses are important plant viruses transmitted exclusively by aphids in a circulative manner via the aphid haemolymph. A chaperonin protein, GroEL, synthesized in aphids by a symbiotic bacterium, Buchnera aphidicola, is hypothesized to bind to virus particles in the haemolymph, thereby promoting transmission. To investigate this hypothesis, the GroEL-binding site for barley yellow dwarf virus (BYDV) was determined in vitro, and the abundance of GroEL protein in different aphid tissues was investigated. Virus binding to a peptide library representing the full GroEL molecule revealed a single binding site that coincides with the site that anchors two GroEL rings to form the native GroEL tetradecamer. In the functional form of the GroEL protein, virus binding would compete with the formation of the two GroEL rings. Using a mAb raised against a Buchnera-specific GroEL epitope, GroEL was detected in Buchnera cells by immunoblotting and immunocytochemistry, but not in the aphid haemolymph, fat body or gut. From the prediction here that GroEL-virus interactions are probably severely limited by competition with other GroEL molecules, and the evidence that GroEL is not available to interact with virus particles in vivo, it is concluded that GroEL-virus interactions are unlikely to contribute to virus transmission by aphids. PMID:21346031

  20. 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.