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Sample records for bt target herbivore

  1. Elevated atmospheric ozone increases concentration of insecticidal Bacillus thuringiensis (Bt) Cry1Ac protein in Bt Brassica napus and reduces feeding of a Bt target herbivore on the non-transgenic parent

    International Nuclear Information System (INIS)

    Sustained cultivation of Bacillus thuringiensis (Bt) transgenic crops requires stable transgene expression under variable abiotic conditions. We studied the interactions of Bt toxin production and chronic ozone exposure in Bt cry1Ac-transgenic oilseed rape and found that the insect resistance trait is robust under ozone elevations. Bt Cry1Ac concentrations were higher in the leaves of Bt oilseed rape grown under elevated ozone compared to control treatment, measured either per leaf fresh weight or per total soluble protein of leaves. The mean relative growth rate of a Bt target herbivore, Plutella xylostella L. larvae was negative on Bt plants in all ozone treatments. On the non-transgenic plants, larval feeding damage was reduced under elevated ozone. Our results indicate the need for monitoring fluctuations in Bt toxin concentrations to reveal the potential of ozone exposure for altering dosing of Bt proteins to target and non-target herbivores in field environments experiencing increasing ozone pollution. - Elevated atmospheric ozone can induce fluctuations in insecticidal protein concentrations in transgenic plants

  2. Elevated atmospheric ozone increases concentration of insecticidal Bacillus thuringiensis (Bt) Cry1Ac protein in Bt Brassica napus and reduces feeding of a Bt target herbivore on the non-transgenic parent

    Energy Technology Data Exchange (ETDEWEB)

    Himanen, Sari J. [University of Kuopio, Department of Environmental Science, P.O. Box 1627, FIN-70211 Kuopio (Finland)], E-mail: sari.himanen@uku.fi; Nerg, Anne-Marja [University of Kuopio, Department of Environmental Science, P.O. Box 1627, FIN-70211 Kuopio (Finland); Nissinen, Anne [University of Kuopio, Department of Environmental Science, P.O. Box 1627, FIN-70211 Kuopio (Finland); MTT Agrifood Research Finland, Plant Protection, FIN-31600 Jokioinen (Finland); Stewart, C. Neal [University of Tennessee, Department of Plant Sciences, Knoxville, TN 37996-4561 (United States); Poppy, Guy M. [University of Southampton, School of Biological Sciences, Southampton SO16 7PX (United Kingdom); Holopainen, Jarmo K. [University of Kuopio, Department of Environmental Science, P.O. Box 1627, FIN-70211 Kuopio (Finland)

    2009-01-15

    Sustained cultivation of Bacillus thuringiensis (Bt) transgenic crops requires stable transgene expression under variable abiotic conditions. We studied the interactions of Bt toxin production and chronic ozone exposure in Bt cry1Ac-transgenic oilseed rape and found that the insect resistance trait is robust under ozone elevations. Bt Cry1Ac concentrations were higher in the leaves of Bt oilseed rape grown under elevated ozone compared to control treatment, measured either per leaf fresh weight or per total soluble protein of leaves. The mean relative growth rate of a Bt target herbivore, Plutella xylostella L. larvae was negative on Bt plants in all ozone treatments. On the non-transgenic plants, larval feeding damage was reduced under elevated ozone. Our results indicate the need for monitoring fluctuations in Bt toxin concentrations to reveal the potential of ozone exposure for altering dosing of Bt proteins to target and non-target herbivores in field environments experiencing increasing ozone pollution. - Elevated atmospheric ozone can induce fluctuations in insecticidal protein concentrations in transgenic plants.

  3. Bt crop effects on functional guilds of non-target arthropods: a meta-analysis.

    Directory of Open Access Journals (Sweden)

    L LaReesa Wolfenbarger

    Full Text Available BACKGROUND: Uncertainty persists over the environmental effects of genetically-engineered crops that produce the insecticidal Cry proteins of Bacillus thuringiensis (Bt. We performed meta-analyses on a modified public database to synthesize current knowledge about the effects of Bt cotton, maize and potato on the abundance and interactions of arthropod non-target functional guilds. METHODOLOGY/PRINCIPAL FINDINGS: We compared the abundance of predators, parasitoids, omnivores, detritivores and herbivores under scenarios in which neither, only the non-Bt crops, or both Bt and non-Bt crops received insecticide treatments. Predators were less abundant in Bt cotton compared to unsprayed non-Bt controls. As expected, fewer specialist parasitoids of the target pest occurred in Bt maize fields compared to unsprayed non-Bt controls, but no significant reduction was detected for other parasitoids. Numbers of predators and herbivores were higher in Bt crops compared to sprayed non-Bt controls, and type of insecticide influenced the magnitude of the difference. Omnivores and detritivores were more abundant in insecticide-treated controls and for the latter guild this was associated with reductions of their predators in sprayed non-Bt maize. No differences in abundance were found when both Bt and non-Bt crops were sprayed. Predator-to-prey ratios were unchanged by either Bt crops or the use of insecticides; ratios were higher in Bt maize relative to the sprayed non-Bt control. CONCLUSIONS/SIGNIFICANCE: Overall, we find no uniform effects of Bt cotton, maize and potato on the functional guilds of non-target arthropods. Use of and type of insecticides influenced the magnitude and direction of effects; insecticde effects were much larger than those of Bt crops. These meta-analyses underscore the importance of using controls not only to isolate the effects of a Bt crop per se but also to reflect the replacement of existing agricultural practices. Results will

  4. The cultivation of Bt corn producing Cry1Ac toxins does not adversely affect non-target arthropods.

    Directory of Open Access Journals (Sweden)

    Yanyan Guo

    Full Text Available Transgenic corn producing Cry1Ac toxins from Bacillus thuringiensis (Bt provides effective control of Asian corn borer, Ostrinia furnacalis (Guenée, and thus reduces insecticide applications. However, whether Bt corn exerts undesirable effects on non-target arthropods (NTAs is still controversial. We conducted a 2-yr study in Shangzhuang Agricultural Experiment Station to assess the potential impact of Bt corn on field population density, biodiversity, community composition and structure of NTAs. On each sampling date, the total abundance, Shannon's diversity index, Pielou's evenness index and Simpson's diversity index were not significantly affected by Bt corn as compared to non-Bt corn. The "sampling dates" had a significant effect on these indices, but no clear tendencies related to "Bt corn" or "sampling dates X corn variety" interaction were recorded. Principal response curve analysis of variance indicated that Bt corn did not alter the distribution of NTAs communities. Bray-Curtis dissimilarity and distance analysis showed that Cry1Ac toxin exposure did not increase community dissimilarities between Bt and non-Bt corn plots and that the evolution of non-target arthropod community was similar on the two corn varieties. The cultivation of Bt corn failed to show any detrimental evidence on the density of non-target herbivores, predators and parasitoids. The composition of herbivores, predators and parasitoids was identical in Bt and non-Bt corn plots. Taken together, results from the present work support that Bt corn producing Cry1Ac toxins does not adversely affect NTAs.

  5. Impact of single-gene and dual-gene Bt broccoli on the herbivore Pieris rapae (Lepidoptera: Pieridae) and its pupal endoparasitoid Pteromalus puparum (Hymenoptera: Pteromalidae).

    Science.gov (United States)

    Chen, Mao; Zhao, Jian-zhou; Shelton, Anthony M; Cao, Jun; Earle, Elizabeth D

    2008-08-01

    Transgenic brassica crops producing insecticidal proteins from Bacillus thuringiensis (Bt) are being investigated as candidates for field release to control lepidopteran pests. Information on the potential impact of Bt brassica crops on pests and non-target natural enemies is needed as part of an environmental risk assessment prior to the commercial release. This first tier study provides insight into the tritrophic interactions among Bt broccoli plants, the herbivore Pieris rapae and its parasitoid Pteromalus puparum. We first evaluated the efficacy of three types of Bt broccoli plants, cry1Ac, cry1C and cry1Ac + cry1C, on different instars of P. rapae. Bt broccoli effectively controlled P. rapae larvae, although later instars were more tolerant. The efficacy of different Bt broccoli plants on P. rapae larvae was consistently cry1Ac > cry1Ac + cry1C > cry1C. When the parasitoid P. puparum developed in a P. rapae pupa (host) that had developed from Bt plant-fed older larvae, developmental time, total number and longevity of the P. puparum generated from the Bt plant-fed host were significantly affected compared with those generated from the non-Bt control plant-fed host. Simultaneously, negative effects on P. rapae pupae were found, i.e. pupal length, width and weight were significantly reduced after older P. rapae larvae fed on different Bt plants for 1 or 2 days. Cry1C toxin was detected using ELISA in P. rapae pupae after older larvae fed on cry1C broccoli. However, no Cry1C toxin was detected in newly emerged P. puparum adults developing in Bt-fed hosts. Only a trace amount of toxin was detected from entire P. puparum pupae dissected from the Bt plant-fed host. Moreover, no negative effect was found on the progeny of P. puparum developing from the Bt plant-fed host when subsequently supplied with a healthy host, P. rapae pupae. The reduced quality of the host appears to be the only reason for the observed deleterious effects on P. puparum. Our data suggest that

  6. Climate change and genetically modified insecticidal plants. Plant-herbivore interactions and secondary chemistry of Bt Cry1Ac-toxin producing oilseed rape (Brassica napus L.) under elevated CO{sub 2} or O{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Himanen, S.

    2008-07-01

    Transgenic insect-resistant plants producing Bacillus thuringiensis (Bt) crystalline endotoxins are the first commercial applications of genetically modified crops and their use has steadily expanded over the last ten years. Together with the expanding agricultural use of transgenic crops, climate change is predicted to be among the major factors affecting agriculture in the coming years. Plants, herbivores and insects of higher trophic levels are all predicted to be affected by the current atmospheric climate change. However, only very few studies to date have addressed the sustained use and herbivore interactions of Bt-producing plants under the influence of these abiotic factors. The main objective of this study was to comparatively assess the performance of a Bt Cry1Ac toxin-producing oilseed rape line and its non-transgenic parent line in terms of vegetative growth and allocation to secondary defence compounds (glucosinolates and volatile terpenoids), and the performance of Bt-target and nontarget insect herbivores as well as tritrophic interaction functioning on these lines. For this, several growth chamber experiments with vegetative stage non-Bt and Bt plants facing exposures to doubled atmospheric CO{sub 2} level alone or together with increased temperature and different regimes of elevated O{sub 3} were conducted. The main hypothesis of this work was that Bt-transgenic plants have reduced performance or allocation to secondary compounds due to the cost of producing Bt toxin under changed abiotic environments. The Bt-transgenic oilseed rape line exhibited slightly delayed vegetative growth and had increased nitrogen and reduced carbon content compared to the non-transgenic parent line, but the physiological responses (i.e. biomass gain and photosynthesis) of the plant lines to CO{sub 2} and O{sub 3} enhancements were equal. Two aphid species, non-susceptible to Bt Cry1Ac, showed equal performance and reproduction on both plant lines under elevated CO{sub 2

  7. Current situation of pests targeted by Bt crops in Latin America.

    Science.gov (United States)

    Blanco, C A; Chiaravalle, W; Dalla-Rizza, M; Farias, J R; García-Degano, M F; Gastaminza, G; Mota-Sánchez, D; Murúa, M G; Omoto, C; Pieralisi, B K; Rodríguez, J; Rodríguez-Maciel, J C; Terán-Santofimio, H; Terán-Vargas, A P; Valencia, S J; Willink, E

    2016-06-01

    Transgenic crops producing Bacillus thuringiensis- (Bt) insecticidal proteins (Bt crops) have provided useful pest management tools to growers for the past 20 years. Planting Bt crops has reduced the use of synthetic insecticides on cotton, maize and soybean fields in 11 countries throughout Latin America. One of the threats that could jeopardize the sustainability of Bt crops is the development of resistance by targeted pests. Governments of many countries require vigilance in measuring changes in Bt-susceptibility in order to proactively implement corrective measures before Bt-resistance is widespread, thus prolonging the usefulness of Bt crops. A pragmatic approach to obtain information on the effectiveness of Bt-crops is directly asking growers, crop consultants and academics about Bt-resistance problems in agricultural fields, first-hand information that not necessarily relies on susceptibility screens performed in laboratories. This type of information is presented in this report. Problematic pests of cotton and soybeans in five Latin American countries currently are effectively controlled by Bt crops. Growers that plant conventional (non-Bt) cotton or soybeans have to spray synthetic insecticides against multiple pests that otherwise are controlled by these Bt crops. A similar situation has been observed in six Latin American countries where Bt maize is planted. No synthetic insecticide applications are used to control corn pests because they are controlled by Bt maize, with the exception of Spodoptera frugiperda. While this insect in some countries is still effectively controlled by Bt maize, in others resistance has evolved and necessitates supplemental insecticide applications and/or the use of Bt maize cultivars that express multiple Bt proteins. Partial control of S. frugiperda in certain countries is due to its natural tolerance to the Bt bacterium. Of the 31 pests targeted and controlled by Bt crops in Latin America, only S. frugiperda has shown

  8. 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...

  9. Impact of Bt potatoes on non-target arthropods

    Czech Academy of Sciences Publication Activity Database

    Nedvěd, Oldřich; Spitzer, Lukáš; Kalushkov, P.

    České Budějovice: Biology Centre of Academy of Sciences of the Czech Republic, 2009 - (Sehnal, F.; Drobník, J.), s. 67-67 ISBN 978-80-86668-05-3 Institutional research plan: CEZ:AV0Z50070508 Keywords : Bt potatoes Subject RIV: GF - Plant Pathology, Vermin, Weed, Plant Protection

  10. Competitive release and outbreaks of non-target pests associated with transgenic Bt cotton.

    Science.gov (United States)

    Zeilinger, Adam R; Olson, Dawn M; Andow, David A

    2016-06-01

    The adoption of transgenic Bt cotton has, in some cases, led to environmental and economic benefits through reduced insecticide use. However, the distribution of these benefits and associated risks among cotton growers and cotton-growing regions has been uneven due in part to outbreaks of non-target or secondary pests, thereby requiring the continued use of synthetic insecticides. In the southeastern USA, Bt cotton adoption has resulted in increased abundance of and damage from stink bug pests, Euschistus servus and Nezara viridula (Heteroptera: Pentatomidae). While the impact of increased stink bug abundance has been well-documented, the causes have remained unclear. We hypothesize that release from competition with Bt-susceptible target pests may drive stink bug outbreaks in Bt cotton. We first examined the evidence for competitive release of stink bugs through meta-analysis of previous studies. We then experimentally tested if herbivory by Bt-susceptible Helicoverpa zea increases stink bug leaving rates and deters oviposition on non-Bt cotton. Consistent with previous studies, we found differences in leaving rates only for E servus, but we found that both species strongly avoided ovipositing on H. zea-damaged plants. Considering all available evidence, competitive release of stink bug populations in Bt cotton likely contributes to outbreaks, though the relative importance of competitive release remains an open question. Ecological risk assessments of Bt crops and other transgenic insecticidal crops would benefit from greater understanding of the ecological mechanisms underlying non-target pest outbreaks and greater attention to indirect ecological effects more broadly. PMID:27509747

  11. Bt Crop Effects on Functional Guilds of Non-target Arthropods: A Meta-Analysis

    Science.gov (United States)

    Uncertainty continues to persist over the potential environmental effects of crops genetically engineered to produce the insecticidal Cry toxins of Bacillus thuringiensis (Bt). Little work has examined broader impacts on ecological function of non-target species within agroecosystems. Here we use me...

  12. The Cultivation of Bt Corn Producing Cry1Ac Toxins Does Not Adversely Affect Non-Target Arthropods

    OpenAIRE

    Yanyan Guo; Yanjie Feng; Yang Ge; Guillaume Tetreau; Xiaowen Chen; Xuehui Dong; Wangpeng Shi

    2014-01-01

    Transgenic corn producing Cry1Ac toxins from Bacillus thuringiensis (Bt) provides effective control of Asian corn borer, Ostrinia furnacalis (Guenée), and thus reduces insecticide applications. However, whether Bt corn exerts undesirable effects on non-target arthropods (NTAs) is still controversial. We conducted a 2-yr study in Shangzhuang Agricultural Experiment Station to assess the potential impact of Bt corn on field population density, biodiversity, community composition and structure o...

  13. Extrapolating non-target risk of Bt crops from laboratory to field

    OpenAIRE

    Jian J Duan; Lundgren, Jonathan G.; Naranjo, Steve; Marvier, Michelle

    2009-01-01

    The tiered approach to assessing ecological risk of insect-resistant transgenic crops assumes that lower tier laboratory studies, which expose surrogate non-target organisms to high doses of insecticidal proteins, can detect harmful effects that might be manifested in the field. To test this assumption, we performed meta-analyses comparing results for non-target invertebrates exposed to Bacillus thuringiensis (Bt) Cry proteins in laboratory studies with results derived from independent field ...

  14. Identification of relevant non-target organisms exposed to weevil-resistant Bt sweetpotato in Uganda

    OpenAIRE

    Rukarwa, R. J.; Mukasa, S. B.; Odongo, B.; Ssemakula, G.; Ghislain, M.

    2013-01-01

    Assessment of the impact of transgenic crops on non-target organisms (NTO) is a prerequisite to their release into the target environment for commercial use. Transgenic sweetpotato varieties expressing Cry proteins (Bt sweetpotato) are under development to provide effective protection against sweetpotato weevils (Coleoptera) which cause severe economic losses in sub-Saharan Africa. Like any other pest control technologies, genetically engineered crops expressing insecticidal proteins need to ...

  15. Does Bt maize cultivation affect the non-target insect community in the agro ecosystem?

    Directory of Open Access Journals (Sweden)

    Daniela Chaves Resende

    2016-03-01

    Full Text Available ABSTRACT The cultivation of genetically modified crops in Brazil has led to the need to assess the impacts of this technology on non-target species. Under field conditions, the potential effect on insect biodiversity was evaluated by comparing a homogeneous corn field with conventional and transgenic maize, expressing different Bt proteins in seven counties of Minas Gerais, Brazil. The richness pattern of non-target insect species, secondary pests and natural enemies were observed. The results do not support the hypothesis that Bt protein affects insect biodiversity. The richness and diversity data of insects studied were dependent on the location and other factors, such as the use of insecticides, which may be a major factor where they are used.

  16. Bt crop effects on functional guilds of non-target arthropods: A meta-analysis (journal)

    Science.gov (United States)

    Background: Uncertainty persists over the environmental effects of genetically-engineered crops that produce the insecticidal Cry proteins of Bacillus thuringiensis (Bt). We performed meta-analyses on a modified public database to synthesize current knowledge about the effects of...

  17. Impact of Bt crops on non-target organisms – 3 systematic reviews

    Science.gov (United States)

    The cultivation of genetically modified (GM) crops producing Cry toxins, originating from the bacterium Bacillus thuringiensis (Bt), has raised environmental concerns over their sustainable use and consequences for biodiversity and ecosystem services in agricultural land. During the last two decades...

  18. Lack of effect of Bt-corn on the non-target arthropods

    Czech Academy of Sciences Publication Activity Database

    Habuštová, Oxana; Hussein, Hany; Doležal, Petr; Spitzer, Lukáš; Růžička, Vlastimil; Sehnal, František

    Durban: Entomological Society of Southern Africa, 2008. s. 5-5. ISBN N. [ICE 2008. International Congress of Entomology /23./. 06.07.2008-12.07.2008, Durban] Institutional research plan: CEZ:AV0Z50070508 Keywords : Bt-corn Subject RIV: GF - Plant Pathology, Vermin, Weed, Plant Protection

  19. Impacts of Bt crops on non-target organisms and insecticide use patterns

    Science.gov (United States)

    Bacillus thuringiensis (Bt), a bacterium capable of producing insecticidal proteins is ubiquitous in the environment, and the genes coding for these proteins are now becoming ubiquitous in major crop plants via recombinant DNA technology where they provide host plant resistance to major lepidopteran...

  20. Leaf surface factors of transgenic Bt cotton associated with the feeding behaviors of cotton aphids: A case study on non-target effects

    Institute of Scientific and Technical Information of China (English)

    XUE Kun; DENG Su; WANG RongJiang; YAN FengMing; XU ChongRen

    2008-01-01

    The present paper reports case study results of the risk assessment of transgenic Bt cotton on a non-target pest, cotton aphid, Aphis gossypii. Several types of techniques, i.e., electrical penetration graph (EPG), light and electron microscopy, bioessays and chemical analysis, were applied to investigate physical and chemical leaf factors of 2 transgenic Bt cotton lines(GK12 and GK19) and their parental non-Bt cotton line (Simian3) associated with searching and feeding behaviors of cotton aphids on leaves or leaf extracts of cotton plants. EPG results showed that there were some differences among behaviors of cotton aphids on 2 Bt cotton and 1 non-Bt cotton lines. Cotton aphids performed similarly to leaf surface extracts from 3 cotton lines; and leaf surface chemicals, mainly volatiles and waxes,were almost identical in the components and concentrations among the cotton lines. However, three cotton lines were quite different from each other in the densities of certain kinds of covering trichomes.Therefore, the relationships between the physical characteristics and the searching behaviors of cotton aphids on the three cotton lines were constructed as the regression equations. Glandular trichomes and covering trichomes with 5 branches Influenced the cotton aphids' searching behaviors effectively;and other trichomes with other branches affected aphids in varying ways. These results demonstrated that leaf surface physical factors of transgenic Bt cotton lines different from their parental non-Bt line could affect the penetration behaviors of non-target cotton aphids. Cotton aphids penetrate and feed more easily on two Bt cotton lines than on the non-Bt cotton line.

  1. Leaf surface factors of transgenic Bt cotton associated with the feeding behaviors of cotton aphids:A case study on non-target effects

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    The present paper reports case study results of the risk assessment of transgenic Bt cotton on a non-target pest, cotton aphid, Aphis gossypii. Several types of techniques, i.e., electrical penetration graph (EPG), light and electron microscopy, bioassays and chemical analysis, were applied to investigate physical and chemical leaf factors of 2 transgenic Bt cotton lines (GK12 and GK19) and their pa-rental non-Bt cotton line (Simian3) associated with searching and feeding behaviors of cotton aphids on leaves or leaf extracts of cotton plants. EPG results showed that there were some differences among behaviors of cotton aphids on 2 Bt cotton and 1 non-Bt cotton lines. Cotton aphids performed similarly to leaf surface extracts from 3 cotton lines; and leaf surface chemicals, mainly volatiles and waxes, were almost identical in the components and concentrations among the cotton lines. However, three cotton lines were quite different from each other in the densities of certain kinds of covering trichomes. Therefore, the relationships between the physical characteristics and the searching behaviors of cotton aphids on the three cotton lines were constructed as the regression equations. Glandular trichomes and covering trichomes with 5 branches influenced the cotton aphids’ searching behaviors effectively; and other trichomes with other branches affected aphids in varying ways. These results demonstrated that leaf surface physical factors of transgenic Bt cotton lines different from their parental non-Bt line could affect the penetration behaviors of non-target cotton aphids. Cotton aphids penetrate and feed more easily on two Bt cotton lines than on the non-Bt cotton line.

  2. Updating risk management recommendations to limit exposure of non-target Lepidoptera of conservation concern in protected habitats to Bt-maize pollen

    OpenAIRE

    Arpaia, Salvatore; Birch, Andrew Nicholas Edmund; Chesson, Andrew; Patrick du Jardin, Patrick; Gathmann, Achim; Gropp, Jürgen; Herman, Lieve; Hoen-Sorteberg, Hilde-Gunn; Jones, Huw; Kiss, József; Kleter, Gijs; Løvik, Martinus; Messéan, Antoine; Perry, Joe; Tebbe, Christoph

    2015-01-01

    Using mathematical modelling, the EFSA GMO Panel has previously quantified the risk to non-target (NT) Lepidoptera of conservation concern, potentially occurring within protected habitats, associated with the ingestion of Bt-maize pollen deposited on their host plants. To reduce the estimated larval mortality to a negligible level, an isolation distance of 20 and 30 m was recommended between protected habitats and the nearest fields of maize MON 810/Bt11 and 1507, respectively. Here, the EFSA...

  3. Acquisition of Cry1Ac Protein by Non-Target Arthropods in Bt Soybean Fields

    OpenAIRE

    Huilin Yu; Jörg Romeis; Yunhe Li; Xiangju Li; Kongming Wu

    2014-01-01

    Soybean tissue and arthropods were collected in Bt soybean fields in China at different times during the growing season to investigate the exposure of arthropods to the plant-produced Cry1Ac toxin and the transmission of the toxin within the food web. Samples from 52 arthropod species/taxa belonging to 42 families in 10 orders were analysed for their Cry1Ac content using enzyme-linked immunosorbent assay (ELISA). Among the 22 species/taxa for which three samples were analysed, toxin concentra...

  4. Risk assessment of Bt crops on the non-target plant-associated insects and soil organisms.

    Science.gov (United States)

    Yaqoob, Amina; Shahid, Ahmad Ali; Samiullah, Tahir Rehman; Rao, Abdul Qayyum; Khan, Muhammad Azmat Ullah; Tahir, Sana; Mirza, Safdar Ali; Husnain, Tayyab

    2016-06-01

    Transgenic plants containing Bacillus thuringiensis (Bt) genes are being cultivated worldwide to express toxic insecticidal proteins. However, the commercial utilisation of Bt crops greatly highlights biosafety issues worldwide. Therefore, assessing the risks caused by genetically modified crops prior to their commercial cultivation is a critical issue to be addressed. In agricultural biotechnology, the goal of safety assessment is not just to identify the safety of a genetically modified (GM) plant, rather to demonstrate its impact on the ecosystem. Various experimental studies have been made worldwide during the last 20 years to investigate the risks and fears associated with non-target organisms (NTOs). The NTOs include beneficial insects, natural pest controllers, rhizobacteria, growth promoting microbes, pollinators, soil dwellers, aquatic and terrestrial vertebrates, mammals and humans. To highlight all the possible risks associated with different GM events, information has been gathered from a total of 76 articles, regarding non-target plant and soil inhabiting organisms, and summarised in the form of the current review article. No significant harmful impact has been reported in any case study related to approved GM events, although critical risk assessments are still needed before commercialisation of these crops. © 2016 Society of Chemical Industry. PMID:26857894

  5. Transgenic cry1Ab/vip3H+epsps Rice with Insect and Herbicide Resistance Acted No Adverse Impacts on the Population Growth of a Non-Target Herbivore, the White-Backed Planthopper, Under Laboratory and Field Conditions

    Institute of Scientific and Technical Information of China (English)

    LU Zeng-bin; HAN Nai-shun; TIAN Jun-ce; PENG Yu-fa; HU Cui; GUO Yu-yuan; SHEN Zhi-cheng; YE Gong-yin

    2014-01-01

    Numerous Bt rice lines expressing Cry protein derived from Bacillus thuringiensis Berliner (Bt) have been developed since 1989. However, the potential risks posed by Bt rice on non-target organisms still remain debate. The white-backed planthopper (WBPH), Sogatella furcifera (Horváth), is one of the most economically important insect pests of rice in Asian countries and also one of the main non-target herbivores of transgenic rice. In the current study, impacts of transgenic cry1Ab/vip3H+epsps rice (G6H1) with both insect and herbicide resistance on WBPH were evaluated to ascertain whether this transgenic rice line had potential risks for this sap-sucking pest under laboratory and ifeld conditions. The laboratory results showed that no signiifcant difference in egg developmental duration, nymphal survival rate and female fecundity was found for WBPH between G6H1 and its non-transgenic isoline (XS110). However, the development duration of nymphs was signiifcantly shorter and female longevity signiifcantly longer when WBPH fed on G6H1 by comparison with those on its control. To verify the results found in laboratory, a 3-yr ifeld trial was conducted to monitor WBPH population using both the vacuum-suction machine and beat plate methods. Although the seasonal density of WBPH nymphs and total density of nymphs and adults were not signiifcantly affected by transgenic rice regardless of the sampling methods, the seasonal density of WBPH adults in transgenic rice plots was slightly lower than that in the control when using the vacuum-suction machine. Based on these results both from laboratory and ifeld, it is clear that our tested transgenic rice line will not lead higher population of WBPH. However, long-term ifeld experiments to monitor the population dynamics of WPBH at large scale need to be conducted to conifrm the present conclusions in future.

  6. Extrapolating non-target risk of Bt crops from laboratory to field

    Science.gov (United States)

    The tiered approach to assessing the ecological risk of insect-resistant transgenic crops rests on the assumption that lower-tier laboratory studies, which expose surrogate non-target organisms to insecticidal proteins, accurately predict the ecological effects of these crops under field conditions....

  7. Call for Papers--Bt Research (ISSN 1925-1939)

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Bt Research (ISSN 1925-1939) is a new launched, open access and peer-reviewed journal that disseminates significant creative reviews and opinions or innovative research work in the area of Bacillus thuringiensis, including the isolation and identification of novel Bt strains, identification of novel Bt toxic genes and their functions, the insecticidal mechanism Bt toxics, Bt genetic engineering, transgenic Bt plants, the resistance mechanism of target-insect to Bt toxins, and the development of novel experimental methods and techniques for Bt Research.

  8. The presence of Bt-transgenic oilseed rape in wild mustard populations affects plant growth.

    Science.gov (United States)

    Liu, Yongbo; Stewart, C Neal; Li, Junsheng; Huang, Hai; Zhang, Xitao

    2015-12-01

    The adventitious presence of transgenic plants in wild plant populations is of ecological and regulatory concern, but the consequences of adventitious presence are not well understood. Here, we introduced Bacillus thuringiensis Cry1Ac (Bt)-transgenic oilseed rape (Bt OSR, Brassica napus) with various frequencies into wild mustard (Brassica juncea) populations. We sought to better understand the adventitious presence of this transgenic insecticidal crop in a wild-relative plant population. We assessed the factors of competition, resource availability and diamondback moth (Plutella xylostella) infestation on plant population dynamics. As expected, Bt OSR performed better than wild mustard in mixed populations under herbivore attack in habitats with enough resources, whereas wild mustard had higher fitness when Bt OSR was rarer in habitats with limited resources. Results suggest that the presence of insect-resistant transgenic plants could decrease the growth of wild mustard and Bt OSR plants and their populations, especially under high herbivore pressure. PMID:26338267

  9. Quality of laboratory studies assessing effects of Bt-proteins on non-target organisms: minimal criteria for acceptability.

    Science.gov (United States)

    De Schrijver, Adinda; Devos, Yann; De Clercq, Patrick; Gathmann, Achim; Romeis, Jörg

    2016-08-01

    The potential risks that genetically modified plants may pose to non-target organisms and the ecosystem services they contribute to are assessed as part of pre-market risk assessments. This paper reviews the early tier studies testing the hypothesis whether exposure to plant-produced Cry34/35Ab1 proteins as a result of cultivation of maize 59122 is harmful to valued non-target organisms, in particular Arthropoda and Annelida. The available studies were assessed for their scientific quality by considering a set of criteria determining their relevance and reliability. As a case-study, this exercise revealed that when not all quality criteria are met, weighing the robustness of the study and its relevance for risk assessment is not obvious. Applying a worst-case expected environmental concentration of bioactive toxins equivalent to that present in the transgenic crop, confirming exposure of the test species to the test substance, and the use of a negative control were identified as minimum criteria to be met to guarantee sufficiently reliable data. This exercise stresses the importance of conducting studies meeting certain quality standards as this minimises the probability of erroneous or inconclusive results and increases confidence in the results and adds certainty to the conclusions drawn. PMID:26980555

  10. IT-BT convergence technology

    International Nuclear Information System (INIS)

    This book explains IT-BT convergence technology as the future technology, which includes a prolog, easy IT-BT convergence technology that has infinite potentials for new value, policy of IT-BT convergence technology showing the potential of smart Korea, IT-BT convergence opening happy future, for the new future of IT powerful nation Korea with IT-BT convergence technology and an epilogue. This book reveals the conception, policy, performance and future of IT-BT convergence technology.

  11. Bacillus thuringiensis (Bt)

    Science.gov (United States)

    2004-01-01

    Bacillus thuringiensis (Bt), a natural bacteria found all over the Earth, has a fairly novel way of getting rid of unwanted insects. Bt forms a protein substance (shown on the right) that is not harmful to humans, birds, fish or other vertebrates. When eaten by insect larvae the protein causes a fatal loss of appetite. For over 25 years agricultural chemical companies have relied heavily upon safe Bt pesticides. New space based research promises to give the insecticide a new dimension in effectiveness and applicability. Researchers from the Consortium for Materials Development in Space along with industrial affiliates such as Abott Labs and Pern State University flew Bt on a Space Shuttle mission in the fall of 1996. Researchers expect that the Shuttle's microgravity environment will reveal new information about the protein that will make it more effective against a wider variety of pests.

  12. Detection and monitoring of insect resistance to transgenic Bt crops

    Institute of Scientific and Technical Information of China (English)

    FANGNENG HUANG

    2006-01-01

    Transgenic crops expressing Bacillus thuringiensis (Bt) endotoxins have become one of the most important tools for managing corn and cotton insect pests in the US and other countries. The widespread adoption of transgenic Bt crops could place a high degree of selection pressure on the target insect populations and accelerate development of resistance, raising concerns about the long-term durability of Bt plants as an effective pest management tool. Conservation of Bt susceptibility in insects has become one of the most active research areas in modern agriculture. One of the key factors for a successful Bt resistance management plan is to have a cost-effective monitoring system that can provide information on: (i) the initial Bt resistance allele frequencies at low levels in field insect populations; and (ii) early shifts in Bt resistance allele frequencies so that proactive measures for managing resistance can be deployed well before field control failures. Developing such a monitoring program has been difficult because: (i) resistance traits that occur at very low frequencies are hard to detect; (ii) many factors affect the sensitivity and accuracy of a Bt resistance monitoring program; and (iii) monitoring resistance is costly. Several novel methods for detecting Bt resistance alleles developed during the last decade have made a cost-effective monitoring system possible. Future studies should focus on how to improve and standardize the methodologies for insect sampling and Bt resistance detection.

  13. Consequences for Protaphorura armata (Collembola: Onychiuridae) following exposure to genetically modified Bacillus thuringiensis (Bt) maize and non-Bt maize

    International Nuclear Information System (INIS)

    Studies on the effect of genetically modified Bacillus thuringiensis (Bt) crops on true soil dwelling non-target arthropods are scarce. The objective of this study was to assess the influence of a 4-week exposure to two Bt maize varieties (Cry1Ab) Cascade and MEB307 on the collembolan Protaphorura armata. For comparison three non-Bt maize varieties, Rivaldo (isogenic to Cascade), Monumental (isogenic to MEB307) and DK242, and two control diets based on baker's yeast (uncontaminated and contaminated with Bt toxin Cry1Ab) were also tested. Due to a lower C:N ratio, individuals reared on yeast performed significantly better in all of the measured endpoints than those reared on maize. P. armata performed equally well when reared on two Bt and three non-Bt maize varieties. Although there were no negative effects of Bt maize in this experiment, we recommend future studies on Bt crops to focus on species interactions in long-term, multi-species experiments. - Protaphorura armata performed equally well when reared on two Bt and three non-Bt maize varieties

  14. Paleobiology of Herbivorous Dinosaurs

    Science.gov (United States)

    Barrett, Paul M.

    2014-05-01

    Herbivorous dinosaurs were abundant, species-rich components of Late Triassic-Cretaceous terrestrial ecosystems. Obligate high-fiber herbivory evolved independently on several occasions within Dinosauria, through the intermediary step of omnivory. Anatomical character complexes associated with this diet exhibit high levels of convergence and morphological disparity, and may have evolved by correlated progression. Dinosaur faunas changed markedly during the Mesozoic, from early faunas dominated by taxa with simple, uniform feeding mechanics to Cretaceous biomes including diverse sophisticated sympatric herbivores; the environmental and biological drivers causing these changes remain unclear. Isotopic, taphonomic, and anatomical evidence implies that niche partitioning reduced competition between sympatric herbivores, via morphological differentiation, dietary preferences, and habitat selection. Large body size in dinosaur herbivores is associated with low plant productivity, and gave these animals prominent roles as ecosystem engineers. Although dinosaur herbivores lived through several major events in floral evolution, there is currently no evidence for plant-dinosaur coevolutionary interactions.

  15. Consequences for Protaphorura armata (Collembola: Onychiuridae) following exposure to genetically modified Bacillus thuringiensis (Bt) maize and non-Bt maize

    DEFF Research Database (Denmark)

    Heckmann, L.-H.; Griffiths, B. S.; Caul, S.;

    2006-01-01

    Studies on the effect of genetically modified Bacillus thuringiensis (Bt) crops on true soil dwelling non-target arthropods are scarce. The objective of this study was to assess the influence of a 4-week exposure to two Bt maize varieties (Cry1Ab) Cascade and MEB307 on the collembolan Protaphorura...

  16. Susceptibility of field populations of sugarcane borer from non-Bt and Bt maize plants to five individual Cry toxins

    Institute of Scientific and Technical Information of China (English)

    Fangneng Huang; Mukti N.Ghimire; B.Rogers Leonard; Yu-Cheng Zhu; Graham P.Head

    2012-01-01

    Sugarcane borer,Diatraea saccharalis (F.),is a major target of transgenic maize expressing Bacillus thuringiensis (Bt) proteins in South America and the US midsouth region.Resistance development in targct pest populations is a major threat to the sustainable use of Bt crops.In our field trials in 2009,a significant number of live borers and plant injury from D.saccharalis were observed in an experimental SmartStaxTM maize line.The objective of this study was to assess the relative susceptibility of two field populations ofD.saccharalis collected from non-Bt and Bt maize plants containing SmartStaxTM traits to five individual Cry proteins.The five Bt proteins included two proteins (Cry1A.105 and Cry2Ab2) that were expressed in SmartStaxTM maize plants and three other common Bt proteins (Cry1Aa,Cry1Ab and Cry1Ac) that were not produced in SmartStaxTM.Larval mortality and growth inhibition on Bt diet of the fourth gcneration after field collections were evaluated 7 days after release of neonates on the diet surface.The laboratory bioassays showed that 50% lethal concentration (LC50) values for Cry1 A.105 and Cry2Ab2 for the population originated from Bt plants were 3.55-and 1.34-fold greater,respectively,than those of the population collected from non-Bt plants.In contrast,relative to the population from non-Bt plants,the LC50 of the population sampled from Bt plants were 3.85-,2.5-and 1.64-fold more sensitive to Cry1Aa,Cry1Ab and Cry1Ac,respectively.The resuits did not provide clear evidence to conclude that the observed field survival of D.saccharalis on Bt plants was associated with increased levels of resistance.

  17. The effects of the presence of Bt-transgenic oilseed rape in wild mustard populations on the rhizosphere nematode and microbial communities.

    Science.gov (United States)

    Liu, Yongbo; Li, Junsheng; Stewart, C Neal; Luo, Zunlan; Xiao, Nengwen

    2015-10-15

    The adventitious presence of transgenic crops in wild plant populations is of ecological and regulatory concern. In this context, their effects on non-target, below-ground organisms are not well understood. Here, we introduced, at various frequencies, Bt-transgenic oilseed rape (OSR, Brassica napus) into wild mustard (Brassica juncea) populations in the presence and absence of the target herbivore (Plutella xylostella). The impacts on soil nematode and microbial communities were assessed in this system. There were no significant changes on the number of nematode genera and abundance in proportions of OSR with mustard. Nonetheless, the Shannon-Wiener and Pielou evenness index was lowest in plant stands containing 50% of Bt-transgenic OSR. Among treatments, there was no significant variation for culturable soil microbes. There was a positive association between foliar herbivory and the abundance of plant parasitic (PP) and cp-3 nematodes, whereas there was no association between herbivory and soil microbial populations. There was no direct effects of the presence of Bt-transgenic OSR in wild mustard populations on the rhizosphere nematode and microbial communities, whereas its indirect effects via aboveground herbivory might be important to consider for biosafety assessments. PMID:26047860

  18. Transgenic Bacillus thuringiensis (Bt rice is safer to aquatic ecosystems than its non-transgenic counterpart.

    Directory of Open Access Journals (Sweden)

    Guangsheng Li

    Full Text Available Rice lines genetically modified with the crystal toxin genes from Bacillus thuringiensis (Bt have experienced rapid development, with biosafety certificates for two Bt rice lines issued in 2009. There has still been no commercial release of these lines yet due to public concerns about human health and environmental risks. Some studies confirmed that Bt rice was as safe as conventional rice to non-target organisms when pesticides were not applied, however, pesticides are still required in Bt rice to control non-lepidopteran pests. In this study, we assessed the environmental effects of two Bt rice lines expressing either the cry1Ab/1Ac or cry2A genes, respectively, by using zooplanktons as indicator species under normal field management practices using pesticides when required. In the whole rice growing season, non-Bt rice was sprayed 5 times while Bt rice was sprayed 2 times, which ensured both rice achieved a normal yield. Field investigations showed that rice type (Bt and non-Bt significantly influenced zooplankton abundance and diversity, which were up to 95% and 80% lower in non-Bt rice fields than Bt rice fields. Laboratory rearing showed that water from non-Bt rice fields was significantly less suitable for the survival and reproduction of Daphnia magna and Paramecium caudatum in comparison with water from Bt rice fields. Higher pesticide residues were detected in the water from non-Bt than Bt rice fields, accounting for the bad performance of zooplankton in non-Bt field water. Our results demonstrate that Bt rice is safer to aquatic ecosystems than non-Bt rice, and its commercialization will be beneficial for biodiversity restoration in rice-based ecosystems.

  19. Target and non-target toxicity of botanical insecticide derived from Couroupita guianensis L. flower against generalist herbivore, Spodoptera litura Fab. and an earthworm, Eisenia foetida Savigny.

    Science.gov (United States)

    Ponsankar, Athirstam; Vasantha-Srinivasan, Prabhakaran; Senthil-Nathan, Sengottayan; Thanigaivel, Annamalai; Edwin, Edward-Sam; Selin-Rani, Selvaraj; Kalaivani, Kandaswamy; Hunter, Wayne B; Alessandro, Rocco T; Abdel-Megeed, Ahmed; Paik, Chae-Hoon; Duraipandiyan, Veeramuthu; Al-Dhabi, Naif Abdullah

    2016-11-01

    Botanical insecticides may provide alternatives to synthetic insecticides for controlling Spodoptera litura (F.) and they are target specific, biodegradable, and harmless to mammals. Eight natural chemical compounds with larvicidal activity were identified from fraction F6 of C. guianensis flower extract. Probit analysis of 95% confidence level exposed an LC50 of 223ppm against S. litura third instar larvae. The growth and development of S. litura was affected in sub-lethal concentrations of fraction F6 (50, 100, 150 and 200ppm) compared to controls. Similarly nutritional indices values decreased significantly compared to controls. Fraction F6 also damaged the gut epithelial layer and brush border membrane (BBM). This study also resolved the effects of toxicity to non-target earthworm treated with fraction F6 and chemical pesticides (monotrophos and cypermethrin) and the results showed that fraction F6 had no harmful effect on E. fetida. Further, fraction F6 was eluted and sub fractions F6c (50ppm) showed high mortality against S. litura third instar larvae. Octacosane from fraction F6c was established and confirmed using IR spectrum and HPLC. The time of retention of fraction F6c was confirmed with the octacosane standard. Fraction F6 of C. guianensis extract caused dose-dependent mortality towards S. litura. Octacosane in fraction F6c was establish to be the prominent chemical compound associated with causing mortality but other compounds present in the fraction F6 were shown to be associated with changes in development of S. litura at low dosages. S. litura at low dosage. Therefore, these findings suggest that octacosane may be one of the major insecticidal compounds affecting S. litura survival. PMID:27476000

  20. Effects of Transgenic Bt Cotton on Insecticide Use and Predatory Insect Abundance

    Science.gov (United States)

    Considerable effort has been expended to determine if crops genetically engineered to produce Bacillus thuringiensis (Bt) toxins harm non-target arthropods. However, if Bt crops kill target pests and thereby reduce insecticide use, this could benefit some non-target arthropods. We analyzed data fr...

  1. Biointensive Integrated Pest Management for Bt Cotton

    OpenAIRE

    N. Sathiah; Balagurunathan, R.; P.S. Shanmugam

    2006-01-01

    Biointensive Integrated Pest Management (BIPM) modules were compared with the Farmers` Package of Practices (FPP) for MECH 162 Bt and MECH 162 N Bt The incidence of leaf hopper, aphids, thrips and whiteflies in different modules was in the order of FPP-MECH 162 Bt > BIPM MECH 162 Bt > BIPM MECH 162 N Bt > FPP MECH 162 N Bt. Natural enemies population were more in BIPM modules than the FPP. Coccinellids such as Menochilus sexmaculatus, Coccinella transversalis and spiders Oxyopes spp., Argiope...

  2. Interaction Between Bt-Transgenic Cotton and the Whitefly’s Parasitoid, Encarsia Formosa (Hymenoptera: Aphelinidae

    Directory of Open Access Journals (Sweden)

    Azimi Solmaz

    2014-07-01

    Full Text Available Transgenic Bt cotton developed against lepidopteran pests may not be compatible with parasitoid of secondary pests such as Bemisia tabaci which attack many plants such as cotton. In this study, the effects of Bt cotton on the demographic parameters of Encarsia formosa, parasitoid of B. tabaci were assessed. The data were analysed using the age specific, two-sex life table parameters. The results indicated that pre-adult developmental time, the total preoviposition period (TPOP and the adult preoviposition period (APOP in the Bt cotton were significantly longer than in the non-Bt cotton. Also, fecundity and body size in both lines were significantly different. The fecundity was 23.64±0.73 and 43.75±0.89 eggs/females in the Bt and non-Bt cotton, respectively. All the population parameters were affected by the Bt cotton. The intrinsic rate of increase (r was 0.15 day-1 in the non-Bt cotton but it was 0.10 day-1 in the Bt cotton. The finite rate of increase (λ was 1.11 day-1 in the non-Bt cotton whilst it was 1.08 in the Bt cotton. The net reproductive rate (R0 in the non-Bt cotton was 36.75 but in the Bt cotton these parameters showed 19.62 offspring/individual. Also, the mean generation time (T in the non-Bt and Bt cotton was 22.69 and 27.79 days, respectively. The results illustrated, that although transgenic crops are effective tools for management of the target pests, they can adversely affect, either directly or indirectly, the natural enemies dependent on these plants.

  3. Decrease in catalase activity of Folsomia candida fed a Bt rice diet

    International Nuclear Information System (INIS)

    Here we report the effects of three Bt-rice varieties and their non-Bt conventional isolines on biological traits including survival, reproduction, and the activities of three antioxidant enzymes superoxide dismutase, catalase and peroxidase, in the Collembolan, Folsomia candida. The reproduction was significantly lower when fed Kemingdao and Huahui1 than those feeding on their non-GM near-isogenic varieties Xiushui and Minghui63 respectively, this can be explained by the differences of plant compositions depended on variety of rice. The catalase activity of F. candida was significantly lower when fed the Bt-rice variety Kemingdao compared to the near-isogenic non-Bt-rice variety Xiushui. This suggests that some Bt-rice varieties may impose environmental stress to collembolans. We emphasize that changes in activity of antioxidant enzymes of non-target organisms are important in understanding the ecological consequences for organisms inhabiting transgenic Bt-rice plantations. - Highlights: → We examine the effects of Bt-rice on Folsomia candida with laboratory test. → The reproduction of F. candida was decreased by two Bt-rice varieties. → Decreased reproduction caused by the differences of varieties or C/N ratio of rice. → The catalase activity was decreased by Bt-rice Kemingdao. → Some Bt-rice may impose environmental stress on NTOs. - The catalase of the collembolan (Folsomia candida) was decreased when fed Bt-rice, Kemingdao.

  4. Dominant inheritance of field-evolved resistance to Bt corn in Busseolafusca.

    Directory of Open Access Journals (Sweden)

    Pascal Campagne

    Full Text Available Transgenic crops expressing Bacillus thuringiensis (Bt toxins have been adopted worldwide, notably in developing countries. In spite of their success in controlling target pests while allowing a substantial reduction of insecticide use, the sustainable control of these pest populations is threatened by the evolution of resistance. The implementation of the "high dose/refuge" strategy for managing insect resistance in transgenic crops aims at delaying the evolution of resistance to Bt crops in pest populations by promoting survival of susceptible insects. However, a crucial condition for the "high dose/refuge" strategy to be efficient is that the inheritance of resistance should be functionally recessive. Busseolafusca developed high levels of resistance to the Bt toxin Cry 1Ab expressed in Bt corn in South Africa. To test whether the inheritance of B. fusca resistance to the Bt toxin could be considered recessive we performed controlled crosses with this pest and evaluated its survival on Bt and non-Bt corn. Results show that resistance of B. fusca to Bt corn is dominant, which refutes the hypothesis of recessive inheritance. Survival on Bt corn was not lower than on non-Bt corn for both resistant larvae and the F1 progeny from resistant × susceptible parents. Hence, resistance management strategies of B. fusca to Bt corn must address non-recessive resistance.

  5. Decrease in catalase activity of Folsomia candida fed a Bt rice diet

    Energy Technology Data Exchange (ETDEWEB)

    Yuan Yiyang, E-mail: yuanyy@ioz.ac.cn [State Key Laboratory of Integrated Management of Pest and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101 (China); Graduate School, Chinese Academy of Sciences, Beijing 100039 (China); Ke Xin, E-mail: xinke@sibs.ac.cn [Shanghai Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, 300 Fenglin Road, Shanghai 200032 (China); Chen Fajun, E-mail: fajunchen@njau.edu.cn [College of Plant Protection, Department of Entomology, Nanjing Agricultural University, Nanjing 210095 (China); Krogh, Paul Henning, E-mail: phk@dmu.dk [Department of Bioscience, University of Aarhus, P.O. Box 314, Vejlsoevej 25, DK-8600 Silkeborg (Denmark); Ge Feng, E-mail: gef@ioz.ac.cn [State Key Laboratory of Integrated Management of Pest and Rodents, Institute of Zoology, Chinese Academy of Sciences, 1 Beichen West Road, Chaoyang District, Beijing 100101 (China)

    2011-12-15

    Here we report the effects of three Bt-rice varieties and their non-Bt conventional isolines on biological traits including survival, reproduction, and the activities of three antioxidant enzymes superoxide dismutase, catalase and peroxidase, in the Collembolan, Folsomia candida. The reproduction was significantly lower when fed Kemingdao and Huahui1 than those feeding on their non-GM near-isogenic varieties Xiushui and Minghui63 respectively, this can be explained by the differences of plant compositions depended on variety of rice. The catalase activity of F. candida was significantly lower when fed the Bt-rice variety Kemingdao compared to the near-isogenic non-Bt-rice variety Xiushui. This suggests that some Bt-rice varieties may impose environmental stress to collembolans. We emphasize that changes in activity of antioxidant enzymes of non-target organisms are important in understanding the ecological consequences for organisms inhabiting transgenic Bt-rice plantations. - Highlights: > We examine the effects of Bt-rice on Folsomia candida with laboratory test. > The reproduction of F. candida was decreased by two Bt-rice varieties. > Decreased reproduction caused by the differences of varieties or C/N ratio of rice. > The catalase activity was decreased by Bt-rice Kemingdao. > Some Bt-rice may impose environmental stress on NTOs. - The catalase of the collembolan (Folsomia candida) was decreased when fed Bt-rice, Kemingdao.

  6. LOBI test BT-15/BT-16 pre-test calculation

    International Nuclear Information System (INIS)

    LOBI is a higher pressure, electrically heated integral system facility simulating a KWU 1300 MW PWR scaled 1:712 by volume, although full scale has been maintained in the vertical direction. In order to complete the test programme before the facility is closed in 1991 a number of tests have been performed in tandem, where the test procedures were compatible. BT-15/BT-16 is one such composite test. In their original form both tests BT-15 and BT-16 simulated a loss of main feedwater transient with delayed auxiliary feedwater injection, with the pumps running in BT-15 and tripped in BT-16. The aim of each test was to investigate the loss of primary/secondary heat transfer as the steam generator secondary sides boiled down, and the subsequent recovery of heat transfer as the auxiliary feedwater was tripped on. Due to a re-scheduling of the test programme there was insufficient time to perform sensitivity studies and so only one, base case, calculation is presented. (author)

  7. Biointensive Integrated Pest Management for Bt Cotton

    Directory of Open Access Journals (Sweden)

    N. Sathiah

    2006-01-01

    Full Text Available Biointensive Integrated Pest Management (BIPM modules were compared with the Farmers` Package of Practices (FPP for MECH 162 Bt and MECH 162 N Bt The incidence of leaf hopper, aphids, thrips and whiteflies in different modules was in the order of FPP-MECH 162 Bt > BIPM MECH 162 Bt > BIPM MECH 162 N Bt > FPP MECH 162 N Bt. Natural enemies population were more in BIPM modules than the FPP. Coccinellids such as Menochilus sexmaculatus, Coccinella transversalis and spiders Oxyopes spp., Argiope spp., Neoscona spp., Araenus spp. and Plexippus spp. were frequently observed in the field trials. Incidence of bollworm population was more in winter field trial than that in the summer field trials. Fruiting bodies damage, open boll, locule and inter locule damage in different modules was in the order of BIPM MECH 162 Bt > FPP MECH 162 Bt > BIPM MECH 162 N Bt > FPP MECH 162 N Bt. Seed cotton yield in BIPM MECH 162 Bt, BIPM MECH 162 N Bt, FPP MECH 162 Bt and FPP MECH 162 N Bt modules at Alandurai field trial were 1920, 1640, 1800 and 1440 kg ha-1. The results indicated the better performance of Bt cotton in both the modules. BIPM approach reduces the insecticide usage. The IPM approach is essential for gaining higher advantage from Bt cotton as it takes care of varying pest situation.

  8. Bt brinjal in India: a long way to go.

    Science.gov (United States)

    Kumar, Sandeep; Misra, Amita; Verma, Alok Kumar; Roy, Ruchi; Tripathi, Anurag; Ansari, Kausar M; Das, Mukul; Dwivedi, Premendra D

    2011-01-01

    Brinjal occupies the major proportion amongst all vegetable crops in India and is vulnerable to many diseases caused by insect-pests, fungus, bacteria and virus. Brinjal production is extensively affected by the insect brinjal fruit and shoot borer. Use of conventional chemical pesticides not only damage environment including the biotic and abiotic components but, also affect human health. Bt Brinjal was developed to combat brinjal fruit and shoot borer that has an advantage minimizing use of chemical pesticides. Extensive biosafety investigations, nutritional studies, substantial equivalence studies, relative toxicity and allergenicity assessment using animal models like Sprague Dawley rats, Brown Norway rats, rabbit, fish, chicken, goats, etc. revealed no significant differences between genetically modified brinjal and its native counterpart. Bt brinjal could effectively control the target pest and was found to be safe for environment and human health. In spite of all the scientific studies, release of Bt Brinjal has been put under moratorium. Indian government has constituted an expert committee to address this issue. In this review we have tried to explore the facts related to Bt Brinjal including its production, use of Bt toxin, use of chemical pesticides in controlling the FSB in native brinjal, along with perspective of public opinion and government initiatives. Key words: Bt Brinjal, agriculture, insecticides, GM foods, agrobacterium, transgenic crops. PMID:21865863

  9. Plant Fitness Assessment for Wild Relatives of Insect Resistant Bt-Crops

    Directory of Open Access Journals (Sweden)

    D. K. Letourneau

    2012-01-01

    Full Text Available When field tests of transgenic plants are precluded by practical containment concerns, manipulative experiments can detect potential consequences of crop-wild gene flow. Using topical sprays of bacterial Bacillus thuringiensis larvicide (Bt and larval additions, we measured fitness effects of reduced herbivory on Brassica rapa (wild mustard and Raphanus sativus (wild radish. These species represent different life histories among the potential recipients of Bt transgenes from Bt cole crops in the US and Asia, for which rare spontaneous crosses are expected under high exposure. Protected wild radish and wild mustard seedlings had approximately half the herbivore damage of exposed plants and 55% lower seedling mortality, resulting in 27% greater reproductive success, 14-day longer life-spans, and 118% more seeds, on average. Seed addition experiments in microcosms and in situ indicated that wild radish was more likely to spread than wild mustard in coastal grasslands.

  10. No direct effects of two transgenic Bt rice lines, T1C-19 and T2A-1, on the arthropod communities.

    Science.gov (United States)

    Lu, Z B; Tian, J C; Han, N S; Hu, C; Peng, Y F; Stanley, David; Ye, G Y

    2014-10-01

    A 2-yr field trial was conducted to assess the impacts of two new transgenic Bt rice lines, T1C-19 expressing Cry1C protein and T2A-1 expressing Cry2A protein, on the arthropod community sampled via vacuum. All the arthropods were classified into five guilds, including herbivores, parasitoids, predators, detritivores, and others. The seasonal density and dominance distribution of each guild and community-level indices (species richness, Shannon-Wiener diversity index, Simpson diversity index, and evenness index) were compared among rice types. Principal response curves were used to investigate the differences of entire arthropod community of Bt rice plots relative to non-Bt rice plots. The results showed no significant difference was detected in the community-level indices and dominance distribution of guilds between Bt and non-Bt rice plots. The seasonal density of herbivores, detritivores, and others as well as density of the arthropod overall community were also not significantly affected by rice types in either year, although the density of predators and parasitoids in Bt rice plots was significantly lower than those in non-Bt rice plots. The lower abundances of Braconidae, Eulophidae, Cyrtorhinus lividipennis (Reuter) (Hemiptera: Miridae), and Theridiidae in Bt rice plots are likely attributed to the lower abundances of prey species or hosts. Principal response curves revealed that arthropod community in Bt was similar with that in non-Bt rice plots. In conclusion, our findings indicate that these two tested Bt rice lines had no marked negative effects on the arthropod community in the paddy fields. PMID:25203669

  11. An Evaluation of Methods for Assessing the Impacts of Bt-maize on Non-target Organisms with Leafhoppers%利用叶蝉评价转基因玉米对非靶标生物的风险

    Institute of Scientific and Technical Information of China (English)

    冯艳杰; 葛阳; 谭树乾; 陈红星; 郭艳艳; 张恺祺; 石旺鹏

    2014-01-01

    The application of transgenic insect-resistant crops has been an important way to replace insecticides. But transgenic insect-resistant crops have potential negative effects, especially the effect on the non-target organisms and resistance to GM. Visual assessment and yellow traps were used for investigating the dynamic of leafhoppers and main arthropods in Cry1Ac transgenic insect-resistant corn field for two years. The study showed that planthoppers and leafhoppers were highly abundant and diverse in maize fields, their mid-term occurrence was 28.9%-43.1% of sucking pest insects, and the population dynamic had no significant difference between Bt-maize and the untreated near-isogenic maize. Leafhoppers were directly exposed to these entomotoxic proteins and could also serve as a source of Cry protein exposure to predatory arthropods. Therefore, it was reasonable to use Auchenorrhyncha in the risk assessment of GM corn. So the risk of Bt corn on non-target organisms could be evaluated using leafhoppers as an indicator species. The results in field tests showed that this method was feasible.%转基因抗虫作物应用是替代杀虫剂的重要途径。但转基因作物可能存负面效应,特别是对非靶标生物的影响及害虫产生抗性。采用直接和陷阱调查结合方法,连续多年对转Cry1Ac抗虫基因玉米实验田叶蝉和主要节肢动物数量动态跟踪调查,结果发现叶蝉是玉米田优势非靶标生物种群之一,中期发生比例占刺吸式害虫的28.9%~43.1%,且种群动态与主要非靶标节肢动物群落动态基本一致。又鉴于叶蝉直接刺吸接触到Bt杀虫蛋白,可直接反映转基因作物对非靶标生物的安全性,因此可利用叶蝉作为转基因抗虫玉米安全性评价指示生物来评价转基因玉米对非靶标生物群落风险,田间测试结果证明此方法是可行的。

  12. Effects of Bt-maize material on the life cycle of the land snail Cantareus aspersus

    DEFF Research Database (Denmark)

    Kramarz, Paulina; de Vaufleury, Annette; Gimbert, Frédéric;

    2009-01-01

    Insect resistant Bt-maize (MON 810) expresses active Cry1Ab endotoxin derived from Bacillus thuringiensis (Bt). Snails constitute non-target soil species potentially exposed to Bt-toxin through consumption of plant material and soil in fields where transgenic plants have been grown. We studied th...

  13. Does the growing of Bt maize change populations or ecological functions of non-target animals compared to the growing of conventional non-GM maize? A systematic review protocol

    Science.gov (United States)

    Since 1996, genetically modified (GM) crops have been grown on an ever increasing area worldwide. Maize producing a Cry protein from the bacterium Bacillus thuringiensis (Bt) was among the first GM crops released for commercial production and it is the only GM crop currently cultivated in Europe. A ...

  14. 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...

  15. Bacillus thuringiensis (Bt) toxin susceptibility and isolation of resistance mutants in the nematode Caenorhabditis elegans.

    Science.gov (United States)

    Marroquin, L D; Elyassnia, D; Griffitts, J S; Feitelson, J S; Aroian, R V

    2000-01-01

    The protein toxins produced by Bacillus thuringiensis (Bt) are the most widely used natural insecticides in agriculture. Despite successful and extensive use of these toxins in transgenic crops, little is known about toxicity and resistance pathways in target insects since these organisms are not ideal for molecular genetic studies. To address this limitation and to investigate the potential use of these toxins to control parasitic nematodes, we are studying Bt toxin action and resistance in Caenorhabditis elegans. We demonstrate for the first time that a single Bt toxin can target a nematode. When fed Bt toxin, C. elegans hermaphrodites undergo extensive damage to the gut, a decrease in fertility, and death, consistent with toxin effects in insects. We have screened for and isolated 10 recessive mutants that resist the toxin's effects on the intestine, on fertility, and on viability. These mutants define five genes, indicating that more components are required for Bt toxicity than previously known. We find that a second, unrelated nematicidal Bt toxin may utilize a different toxicity pathway. Our data indicate that C. elegans can be used to undertake detailed molecular genetic analysis of Bt toxin pathways and that Bt toxins hold promise as nematicides. PMID:10924467

  16. Use of Bt-resistant caterpillars to assess the effect of Cry proteins on beneficial natural enemies

    Science.gov (United States)

    A concern related to the use of insect-resistant Bt-transgenic plants is their potential to harm non-target organisms, especially natural enemies of important crop pests. A few studies purporting to show negative effects of Bt plants on non-target organisms had tremendous negative effects on the per...

  17. Early warning of cotton bollworm resistance associated with intensive planting of Bt cotton in China.

    Directory of Open Access Journals (Sweden)

    Haonan Zhang

    Full Text Available Transgenic crops producing Bacillus thuringiensis (Bt toxins kill some key insect pests, but evolution of resistance by pests can reduce their efficacy. The predominant strategy for delaying pest resistance to Bt crops requires refuges of non-Bt host plants to promote survival of susceptible pests. To delay pest resistance to transgenic cotton producing Bt toxin Cry1Ac, farmers in the United States and Australia planted refuges of non-Bt cotton, while farmers in China have relied on "natural" refuges of non-Bt host plants other than cotton. Here we report data from a 2010 survey showing field-evolved resistance to Cry1Ac of the major target pest, cotton bollworm (Helicoverpa armigera, in northern China. Laboratory bioassay results show that susceptibility to Cry1Ac was significantly lower in 13 field populations from northern China, where Bt cotton has been planted intensively, than in two populations from sites in northwestern China where exposure to Bt cotton has been limited. Susceptibility to Bt toxin Cry2Ab did not differ between northern and northwestern China, demonstrating that resistance to Cry1Ac did not cause cross-resistance to Cry2Ab, and implying that resistance to Cry1Ac in northern China is a specific adaptation caused by exposure to this toxin in Bt cotton. Despite the resistance detected in laboratory bioassays, control failures of Bt cotton have not been reported in China. This early warning may spur proactive countermeasures, including a switch to transgenic cotton producing two or more toxins distinct from Cry1A toxins.

  18. Characterization of NCAM expression and function in BT4C and BT4Cn glioma cells

    DEFF Research Database (Denmark)

    Andersson, A M; Moran, N; Gaardsvoll, H; Linnemann, D; Bjerkvig, R; Laerum, O D; Bock, Elisabeth Marianne

    1991-01-01

    The neural cell adhesion molecule, NCAM, plays an important role in cell-cell adhesion. Therefore, we have studied NCAM expression in the glioma cell lines BT4C and BT4Cn. We demonstrate that the 2 cell lines differ in their metastatic ability; while BT4C cells have a very low capacity for......-substratum binding assay in which the binding of BT4C and BT4Cn cells to NCAM immobilized to glass was assessed. We found thatBT4C cells adhere specifically to NCAM, and that adhesion is inhibited by anti-NCAM Fab'-fragments, while no specific binding of BT4Cn cells to NCAM was observed. The BT4C and BT4Cn cell...... lines thus constitute an important new model system for the study of tumor invasion and metastasis and of the role of cell adhesion molecules in these processes....

  19. The natural refuge policy for Bt cotton (Gossypium L. in Pakistan – a situation analysis

    Directory of Open Access Journals (Sweden)

    Muhammad Sajjad Ali

    2013-07-01

    Full Text Available Bt cotton (event Cry1Ac was formally commercialized in Pakistan in 2010. However, there has been an increasing trend of planting unauthorized Bt cotton germplasm in farmers' fields since 2003 with a high rate of adoption in the core cotton areas especially in the province Punjab. The transgenic cotton technology has provided the growers with substantial economic benefits and has reduced their dependence on pesticides for pest control, especially against Helicoverpa armigera (Hubner. However, keeping in view the capacity of this insect to develop resistance against novel chemical formulations, it is easily speculated that Bt toxin, too, is no exception. Refuge crop policy for mono transgenic crop events has helped in delaying the rate of resistance evolution in the target pests. Thus, in Pakistan, where planting of structured refuge crops along Bt cotton fields is not mandatory, the effectiveness and durability of Bt cotton technology may decrease due to a number of factors which are discussed in this review.

  20. Decrease in catalase activity of Folsomia candida fed a Bt rice diet

    DEFF Research Database (Denmark)

    Yuan, Yiyang; Ke, Xin; Chen, Fajun;

    2011-01-01

    Here we report the effects of three Bt-rice varieties and their non-Bt conventional isolines on biological traits including survival, reproduction, and the activities of three antioxidant enzymes superoxide dismutase, catalase and peroxidase, in the Collembolan, Folsomia candida. The reproduction...... was significantly lower when fed Kemingdao and Huahui1 than those feeding on their non-GM near-isogenic varieties Xiushui and Minghui63 respectively, this can be explained by the differences of plant compositions depended on variety of rice. The catalase activity of F. candida was significantly lower when fed...... the Bt-rice variety Kemingdao compared to the near-isogenic non-Bt-rice variety Xiushui. This suggests that some Bt-rice varieties may impose environmental stress to collembolans. We emphasize that changes in activity of antioxidant enzymes of non-target organisms are important in understanding...

  1. Resistance to Bt maize by western corn rootworm: insights from the laboratory and the field.

    Science.gov (United States)

    Gassmann, Aaron J

    2016-06-01

    Western corn rootworm is a serious pest of maize. Beginning in 2003, management of western corn rootworm included transgenic maize that produces insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt). The first Bt maize hybrids produced Cry3Bb1, but additional Bt toxins have since been introduced, including eCry3.1Ab, mCry3A and Cry34/35Ab1. Laboratory selection experiments found that western corn rootworm could develop resistance to all types of Bt maize following three to seven generations of selection. By 2009 cases of field-evolved resistance to Cry3Bb1 maize had been identified, with populations also showing cross-resistance to mCry3A maize. Factors likely contributing to resistance were the lack of a high dose of Bt toxin for maize targeting rootworm and minimal fitness costs of resistance. PMID:27436740

  2. 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. PMID:25802407

  3. Effects of Bt plants on the development and survival of the parasitoid Cotesia plutellae (Hymenoptera: Braconidae) in susceptible and Bt-resistant larvae of the diamondback moth, Plutella xylostella (Lepidoptera: Plutellidae).

    Science.gov (United States)

    Schuler, Tanja H; Denholm, Ian; Clark, Suzanne J; Stewart, C Neal; Poppy, Guy M

    2004-05-01

    A range of crops have been transformed with delta-endotoxin genes from Bacillus thuringiensis (Bt) to produce transgenic plants with high levels of resistance to lepidopteran pests. Parasitoids are important natural enemies of lepidopteran larvae and the effects of Bt plants on these non-target insects have to be investigated to avoid unnecessary disruption of biological control. This study investigated the effects of Cry1Ac-expressing transgenic oilseed rape (Brassica napus) on the solitary braconid endoparasitoid Cotesia plutellae in small-scale laboratory experiments. C. plutellae is an important natural enemy of the diamondback moth (Plutella xylostella), the most important pest of brassica crops world-wide. Bt oilseed rape caused 100% mortality of a Bt-susceptible P. xylostella strain but no mortality of the Bt-resistant P. xylostella strain NO-QA. C. plutellae eggs laid in Bt-susceptible hosts feeding on Bt leaves hatched but premature host mortality did not allow C. plutellae larvae to complete their development. In contrast, C. plutellae developed to maturity in Bt-resistant hosts fed on Bt oilseed rape leaves and there was no effect of Bt plants on percentage parasitism, time to emergence from hosts, time to adult emergence and percentage adult emergence from cocoons. Weights of female progeny after development in Bt-resistant hosts did not differ between plant types but male progeny was significantly heavier on wildtype plants in one of two experiments. The proportion of female progeny was significantly higher on Bt plants in the first experiment with Bt-resistant hosts but this effect was not observed again when the experiment was repeated. PMID:15121457

  4. A critical assessment of the effects of Bt transgenic plants on parasitoids.

    Science.gov (United States)

    Chen, Mao; Zhao, Jian-Zhou; Collins, Hilda L; Earle, Elizabeth D; Cao, Jun; Shelton, Anthony M

    2008-01-01

    The ecological safety of transgenic insecticidal plants expressing crystal proteins (Cry toxins) from the bacterium Bacillus thuringiensis (Bt) continues to be debated. Much of the debate has focused on nontarget organisms, especially predators and parasitoids that help control populations of pest insects in many crops. Although many studies have been conducted on predators, few reports have examined parasitoids but some of them have reported negative impacts. None of the previous reports were able to clearly characterize the cause of the negative impact. In order to provide a critical assessment, we used a novel paradigm consisting of a strain of the insect pest, Plutella xylostella (herbivore), resistant to Cry1C and allowed it to feed on Bt plants and then become parasitized by Diadegma insulare, an important endoparasitoid of P. xylostella. Our results indicated that the parasitoid was exposed to a biologically active form of the Cy1C protein while in the host but was not harmed by such exposure. Parallel studies conducted with several commonly used insecticides indicated they significantly reduced parasitism rates on strains of P. xylostella resistant to these insecticides. These results provide the first clear evidence of the lack of hazard to a parasitoid by a Bt plant, compared to traditional insecticides, and describe a test to rigorously evaluate the risks Bt plants pose to predators and parasitoids. PMID:18523682

  5. Increased frequency of pink bollworm resistance to Bt toxin Cry1Ac in China.

    Directory of Open Access Journals (Sweden)

    Peng Wan

    Full Text Available Transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt kill some key insect pests, but evolution of resistance by pests can reduce their efficacy. The main approach for delaying pest adaptation to Bt crops uses non-Bt host plants as "refuges" to increase survival of susceptible pests. To delay evolution of pest resistance to transgenic cotton producing Bt toxin Cry1Ac, the United States and some other countries have required refuges of non-Bt cotton, while farmers in China have relied on "natural" refuges of non-Bt host plants other than cotton. The "natural" refuge strategy focuses on cotton bollworm (Helicoverpa armigera, the primary target of Bt cotton in China that attacks many crops, but it does not apply to another major pest, pink bollworm (Pectinophora gossypiella, which feeds almost entirely on cotton in China. Here we report data showing field-evolved resistance to Cry1Ac by pink bollworm in the Yangtze River Valley of China. Laboratory bioassay data from 51 field-derived strains show that the susceptibility to Cry1Ac was significantly lower during 2008 to 2010 than 2005 to 2007. The percentage of field populations yielding one or more survivors at a diagnostic concentration of Cry1Ac increased from 0% in 2005-2007 to 56% in 2008-2010. However, the median survival at the diagnostic concentration was only 1.6% from 2008 to 2010 and failure of Bt cotton to control pink bollworm has not been reported in China. The early detection of resistance reported here may promote proactive countermeasures, such as a switch to transgenic cotton producing toxins distinct from Cry1A toxins, increased planting of non-Bt cotton, and integration of other management tactics together with Bt cotton.

  6. 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...

  7. Plant Defense against Insect Herbivores

    Directory of Open Access Journals (Sweden)

    Søren Bak

    2013-05-01

    Full Text Available Plants have been interacting with insects for several hundred million years, leading to complex defense approaches against various insect feeding strategies. Some defenses are constitutive while others are induced, although the insecticidal defense compound or protein classes are often similar. Insect herbivory induce several internal signals from the wounded tissues, including calcium ion fluxes, phosphorylation cascades and systemic- and jasmonate signaling. These are perceived in undamaged tissues, which thereafter reinforce their defense by producing different, mostly low molecular weight, 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 have adapted to resist plant defenses, and in some cases even sequester the compounds and reuse them in their own defense. Both plant defense and insect adaptation involve metabolic costs, so most plant-insect interactions reach a stand-off, where both host and herbivore survive although their development is suboptimal.

  8. The food and environmental safety of Bt crops

    OpenAIRE

    Koch, Michael S.; Jason M Ward; Levine, Steven L.; Baum, James A.; Vicini, John L.; Hammond, Bruce G.

    2015-01-01

    Bacillus thuringiensis (Bt) microbial pesticides have a 50-year history of safety in agriculture. Cry proteins are among the active insecticidal ingredients in these pesticides, and genes coding for Cry proteins have been introduced into agricultural crops using modern biotechnology. The Cry gene sequences are often modified to enable effective expression in planta and several Cry proteins have been modified to increase biological activity against the target pest(s). Additionally, the domains...

  9. The Food and Environmental Safety of Bt Crops

    OpenAIRE

    Michael Stephen Koch; Jason M Ward; Levine, Steven L.; Baum, James A.; Vicini, John L.; Hammond, Bruce G.

    2015-01-01

    Bt (Bacillus thuringiensis) microbial pesticides have a 50-year history of safe use in agriculture. Cry proteins are among the active insecticidal ingredients in these pesticides, and genes coding for Cry proteins have been introduced into agricultural crops using modern biotechnology. The Cry gene sequences are often modified to enable effective expression in planta and several Cry proteins have been modified to increase biological activity against the target pest(s). Additionally, the domai...

  10. Partnership and Workplace Learning at BT

    Science.gov (United States)

    Education & Training, 2002

    2002-01-01

    Explores BT's partnership with the Communication Workers' Union and London University's Queen Mary and Westfield College and examines its significance for the development of a degree level programme of workplace learning. Describes the programme's philosophy, aims, funding and effectiveness. Incorporates interviews with BT managers, trade union…

  11. 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.

  12. The Food and Environmental Safety of Bt Crops

    Directory of Open Access Journals (Sweden)

    Michael Stephen Koch

    2015-04-01

    Full Text Available Bt (Bacillus thuringiensis microbial pesticides have a 50-year history of safe use in agriculture. Cry proteins are among the active insecticidal ingredients in these pesticides, and genes coding for Cry proteins have been introduced into agricultural crops using modern biotechnology. The Cry gene sequences are often modified to enable effective expression in planta and several Cry proteins have been modified to increase biological activity against the target pest(s. Additionally, the domains of different but structurally conserved Cry proteins can be combined to produce chimeric proteins with enhanced insecticidal properties. Environmental studies are performed and include invertebrates, mammals and avian species. Mammalian studies used to support the food and feed safety assessment are also used to support the wild mammal assessment. In addition to the NTO assessment, the environmental assessment includes a comparative assessment between the Bt crop and the appropriate conventional control that is genetically similar but lacks the introduced trait to address unintended effects. Specific phenotypic, agronomic, and ecological characteristics are measured in the Bt crop and the conventional control to evaluate whether the introduction of the insect resistance has resulted in any changes that might cause ecological harm in terms of altered weed characteristics, susceptibility to pests, or adverse environmental impact. Additionally, environmental interaction data are collected in field experiments for Bt crop to evaluate potential adverse effects. Further to the agronomic and phenotypic evaluation, potential movement of transgenes from a genetically modified crop plants into wild relatives is assessed for a new pest resistance gene in a new crop. This review summarizes the evidence for safety of crops containing Cry proteins for humans, livestock, and other non-target organisms.

  13. The food and environmental safety of Bt crops.

    Science.gov (United States)

    Koch, Michael S; Ward, Jason M; Levine, Steven L; Baum, James A; Vicini, John L; Hammond, Bruce G

    2015-01-01

    Bacillus thuringiensis (Bt) microbial pesticides have a 50-year history of safety in agriculture. Cry proteins are among the active insecticidal ingredients in these pesticides, and genes coding for Cry proteins have been introduced into agricultural crops using modern biotechnology. The Cry gene sequences are often modified to enable effective expression in planta and several Cry proteins have been modified to increase biological activity against the target pest(s). Additionally, the domains of different but structurally conserved Cry proteins can be combined to produce chimeric proteins with enhanced insecticidal properties. Environmental studies are performed and include invertebrates, mammals, and avian species. Mammalian studies used to support the food and feed safety assessment are also used to support the wild mammal assessment. In addition to the NTO assessment, the environmental assessment includes a comparative assessment between the Bt crop and the appropriate conventional control that is genetically similar but lacks the introduced trait to address unintended effects. Specific phenotypic, agronomic, and ecological characteristics are measured in the Bt crop and the conventional control to evaluate whether the introduction of the insect resistance has resulted in any changes that might cause ecological harm in terms of altered weed characteristics, susceptibility to pests, or adverse environmental impact. Additionally, environmental interaction data are collected in field experiments for Bt crop to evaluate potential adverse effects. Further to the agronomic and phenotypic evaluation, potential movement of transgenes from a genetically modified crop plants into wild relatives is assessed for a new pest resistance gene in a new crop. This review summarizes the evidence for safety of crops containing Cry proteins for humans, livestock, and other non-target organisms. PMID:25972882

  14. Natural refuge crops, buildup of resistance, and zero-refuge strategy for Bt cotton in China

    Institute of Scientific and Technical Information of China (English)

    ROZELLE; Scott; WILEN; James

    2010-01-01

    In the context of genetically modified crops expressing the Bacillus thuringiensis (Bt) toxin, a ‘refuge’ refers to a crop of the same or a related species that is planted nearby to enable growth and reproduction of the target pest without the selection pres- sure imposed by the Bt toxin. The goal of this study is to discuss the role of natural refuge crops in slowing down the buildup of resistance of cotton bollworm (CBW), and to evaluate China’s no-refuge policy for Bt cotton. We describe in detail the dif- ferent factors that China should consider in relation to the refuge policy. Drawing on a review of scientific data, economic analyses of other cases, and a simulation exercise using a bio-economic model, we show that in the case of Bt cotton in China, the no-refuge policy is defensible.

  15. Mechanisms of plant defense against insect herbivores

    OpenAIRE

    War, Abdul Rashid; Paulraj, Michael Gabriel; Ahmad, Tariq; BUHROO, Abdul Ahad; Hussain, Barkat; Ignacimuthu, Savarimuthu; Sharma, Hari Chand

    2012-01-01

    Plants respond to herbivory through various morphological, biochemicals, and molecular mechanisms to counter/offset the effects of herbivore attack. The biochemical mechanisms of defense against the herbivores are wide-ranging, highly dynamic, and are mediated both by direct and indirect defenses. The defensive compounds are either produced constitutively or in response to plant damage, and affect feeding, growth, and survival of herbivores. In addition, plants also release volatile organic c...

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

    Science.gov (United States)

    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...

  17. 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

  18. BT799玉米对亚洲玉米螟抗性研究%Resistance of transgenic Bt corn variety BT799 to the Asian corn borer

    Institute of Scientific and Technical Information of China (English)

    王月琴; 何康来; 江帆; 王依冬; 张天涛; 王振营; 白树雄

    2014-01-01

    Objectives] To review the resistance of transgenic Bt corn to target pests which is one of the primarily steps for research and development of insect-resistant, transgenic corn. This review mainly evaluates the resistance of transgenic Cry1Ac gene corn variety BT799 to the Asian corn borer (ACB), Ostrinia furnacalis (Guenée), and measured the quantity of Cry1Ac protein expressed in corn plant tissues. [Methods] Enzyme-linked immunosorbent assays, laboratory bioassay and field studies with artificial infestation were employed in this study. [Results] The expression levels of Cry1Ac protein were 768.0 ng/g (protein/fresh leaves), 1452.8-2978.5 ng/g (protein/dry mass of silk, husk and young kernels). Leaf-feeding rates in field trials indicated that BT799 and CC-2XBT799 were highly resistant to ACB. The survival of ACB larvae feeding on Zhengdan 958K, a single cross hybrid containing BT799, was significantly lower (0-37.5%) than that of larvae that fed on non-Bt Zhengdan 958 (89.9%-100.0%). In addition, larval survival of Cry1Ac-, Cry1Ie-, and Cry1F-selected ACB strains (ACB-AcR, ACB-IeR and ACB-FR) were significantly different when fed on Zhengdan 958K. ACB-IeR had the lowest survival followed by ACB-FR, both of them had significantly lower survival than those that fed on the control Zhengdan 958. However, the survival of ACB-AcR was not significantly different from larvae feeding on the control Zhengdan 958. [Conclusion] These results suggests that the transgenic Bt corn variety BT799 is highly toxic to the ACB and can provide effective control for ACB in the field.%【目的】抗螟性鉴定是转基因抗虫玉米研发的重要一环。本文主要就转基因玉米BT799对亚洲玉米螟的抗性展开评价,同时测定了BT799植株组织中Cry1Ac蛋白的表达量。【方法】采用了酶联免疫吸附测定法(ELISA)、室内生测和田间人工接虫鉴定3种方法。【结果】转基因抗虫玉米BT799组织中Cry1Ac蛋白含量分别为768

  19. BT-blenderen - en undersøgelse af BT's videnskabsjournalistik mellem ideal og praksis

    OpenAIRE

    Høyberg Pedersen, Nanna; Sandfeld Hansen, Frederik; Holm Hansen, Puk; Anthon Sørensen, Kasper

    2012-01-01

    This paper concerns the Danish daily newspaper BT and investigates its take on science-journalism. Our main objective is to see how journalistic ideals are interpreted in the daily work of the science-journalists at the paper. The empirical data consists of interviews with two journalists and an editor from BT, an in-depth text-analysis of three articles from BT with popular scientific topics and four popular science articles written for BT by the students, as a means of reflecting on the pra...

  20. Binding of Bt Cry toxins to lepidopteran midgut aminopeptidase N and the relationship between their interactions with Bt resistance%鳞翅目昆虫氨肽酶N与Bt毒素的结合及其与Bt抗性的关系

    Institute of Scientific and Technical Information of China (English)

    马文静; 韩兰芝; 尹新明; 曹广春; 苏丽娟

    2011-01-01

    随着Bt Cry作物在我国的广泛应用和推广,靶标害虫对其抗性风险已成为Bt Cry作物生态安全研究的重要内容.氨肽酶N(Aminopeptidase N,APN)是位于昆虫中肠刷状缘膜囊泡(Brush Border Membrane Vesicles,BBMV)上Bt Cry毒素重要的受体蛋白之一,它与Bt Cry毒素的结合能力决定了Bt Cry毒素的杀虫活性及昆虫对Bt抗性的产生.本文从APN的结构特征与分类、APN与Bt Cry毒素的结合特异性、结合位点、结合过程中的分子互作机制及APN变异导致昆虫抗性产生几方面系统综述了鳞翅目昆虫中肠Bt Cry受体蛋白-氨肽酶N与Bt Cry 毒素的结合及其与Bt抗性关系的研究进展.%With the wide application and popularization of Bt Cry crop, the resistance of target pests a-gainst Bt Cry crop has become the focus of studies on its ecological safety. Aminopeptidase N (APN) is one of Bt-toxin receptor proteins located in brush border membrane vesicles ( BBMV) of insect midgut. Its binding capability with Bt Cry toxin determines the toxin's insecticidal spectrum and insect Bt resistance. This paper systemically reviews the progress of researches on APN structural characteristics and classfication, the binding feature, binding sites and interactions mechanism of Bt Cry toxin and APN as well as Bt resistance resulting from APN mutations.

  1. 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

  2. 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

  3. Effects of Bt-transgenic rice cultivation on planktonic communities in paddy fields and adjacent ditches.

    Science.gov (United States)

    Liu, Yongbo; Liu, Fang; Wang, Chao; Quan, Zhanjun; Li, Junsheng

    2016-09-15

    The non-target effects of transgenic plants are issues of concern; however, their impacts in cultivated agricultural fields and adjacent natural aquatic ecosystems are poorly understood. We conducted field experiments during two growing seasons to determine the effects of cultivating Bacillus thuringiensis (Bt)-transgenic rice on the phytoplankton and zooplankton communities in a paddy field and an adjacent ditch. Bt toxin was detected in soil but not in water. Water quality was not significantly different between non-Bt and Bt rice fields, but varied among up-, mid- and downstream locations in the ditch. Cultivation of Bt-transgenic rice had no effects on zooplankton communities. Phytoplankton abundance and biodiversity were not significantly different between transgenic and non-transgenic rice fields in 2013; however, phytoplankton were more abundant in the transgenic rice field than in the non-transgenic rice field in 2014. Water quality and rice type explained 65.9% and 12.8% of this difference in 2014, respectively. Phytoplankton and zooplankton were more abundant in mid- and downstream, than upstream, locations in the ditch, an effect that we attribute to water quality differences. Thus, the release of Bt toxins into field water during the cultivation of transgenic crops had no direct negative effects on plankton community composition, but indirect effects that alter environmental conditions should be taken into account during the processes of management planning and policymaking. PMID:27219503

  4. 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.

  5. Early Detection and Mitigation of Resistance to Bt Maize by Western Corn Rootworm (Coleoptera: Chrysomelidae).

    Science.gov (United States)

    Andow, David A; Pueppke, Steven G; Schaafsma, Arthur W; Gassmann, Aaron J; Sappington, Thomas W; Meinke, Lance J; Mitchell, Paul D; Hurley, Terrance M; Hellmich, Richard L; Porter, R Pat

    2016-02-01

    Transgenic Bt maize that produces less than a high-dose has been widely adopted and presents considerable insect resistance management (IRM) challenges. Western corn rootworm, Diabrotica virgifera virgifera LeConte, has rapidly evolved resistance to Bt maize in the field, leading to local loss of efficacy for some corn rootworm Bt maize events. Documenting and responding to this resistance has been complicated by a lack of rapid diagnostic bioassays and by regulatory triggers that hinder timely and effective management responses. These failures are of great concern to the scientific and agricultural community. Specific challenges posed by western corn rootworm resistance to Bt maize, and more general concerns around Bt crops that produce less than a high-dose of Bt toxin, have caused uncertainty around current IRM protocols. More than 15 years of experience with IRM has shown that high-dose and refuge-based IRM is not applicable to Bt crops that produce less than a high-dose. Adaptive IRM approaches and pro-active, integrated IRM-pest management strategies are needed and should be in place before release of new technologies that produce less than a high-dose. We suggest changes in IRM strategies to preserve the utility of corn rootworm Bt maize by 1) targeting local resistance management earlier in the sequence of responses to resistance and 2) developing area-wide criteria to address widespread economic losses. We also favor consideration of policies and programs to counteract economic forces that are contributing to rapid resistance evolution. PMID:26362989

  6. ISOLATION, CHARACTERIZATION OF PHYTASE PRODUCING BACILLUS SUBTILS BtRS2 FROM THE RHIZOSPHERE SOIL OF Bt COTTON FIELD

    OpenAIRE

    K. Usha Sri

    2013-01-01

    Soil samples of Bt Rhizosphere were collected from Bt cotton growing area of Andhra Pradesh, India and was used as a source material for isolation and screening of phytase producing bacteria. 19Bacteria were isolated from Bt Rhizosphere. Phytase enzyme activity of the cultures was screened on modified phytase solubulizing medium (MPSM). The result inferred that six isolates BtRS1 to BtRS6 were strongly positive in enzyme activity than six of other microorganisms while seven isolates were foun...

  7. Limites du riz Bt dans le contexte entomologique de la riziculture en Afrique sub-saharienne et à Madagascar (synthèse bibliographique

    Directory of Open Access Journals (Sweden)

    Silvie, P.

    2013-01-01

    Full Text Available Limitations of Bt rice in the entomological rice cropping context in sub-Saharan Africa and Madagascar. A review. In sub-Saharan African countries and Madagascar, rice crops host many insect species, which have been inventoried and studied for almost 40 years. Management of these rice pests using synthetic chemical pesticides is not common practice. In Asia, genetically modified rice varieties (Bt rice resistant to some insects were engineered in the 1990s. In 2009, two Bt rice varieties were authorized to be marketed in China. Bt rice is not grown in African countries. We therefore decided to analyze the published literature on Bt rice and to compare the findings with the current insect pest situation in African rice fields. The activity spectrum and the efficacy of Bt toxins represent the first limitation encountered in the use of currently available Bt rice varieties. For instance, the effect of Bt toxins against Diptera (Diopsidae species is unknown, since these species only occur in Africa. On the African continent and in Madagascar, it would be essential to enhance or promote taxonomic, biological and ecological knowledge concerning rice pests and to more accurately measure the impact of various insect species on crop yields. The broad range of rice insect pests, including insect vectors of disease, the risk of target insects developing resistance to Bt toxins and the lack of economic assessments suggest that, with the current state of knowledge in Africa, it would be inappropriate to introduce currently available Bt rice varieties there.

  8. 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.

  9. 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

  10. Bacillus thuringiensis (Bt) transgenic crop: an environment friendly insect-pest management strategy.

    Science.gov (United States)

    Kumar, Suresh; Chandra, Amaresh; Pandey, K C

    2008-09-01

    Introduction of DDT (dichloro-diphenyl-trichloroethane) and following move towards indiscriminate use of synthetic chemical insecticides led to the contamination of water and food sources, poisoning of non-target beneficial insects and development of insect-pests resistant to the chemical insecticides. Increased public concems about the adverse environmental effects of indiscriminate use of chemical insecticides prompted search of altemative methods for insect-pest control. One of the promising alternatives has been the use of biological control agents. There is well-documented history of safe application of Bt (B. thuringiensis, a gram positive soil bacterium) as effective biopesticides and a number of reports of expression of delta-endotoxin gene(s) in crop plants are available. Only a few insecticidal sprays are required on Bt transgenic crops, which not only save cost and time, but also reduce health risks. Insects exhibit remarkable ability to develop resistance to different insecticidal compounds, which raises concern about the unsystematic use of Bt transgenic technology also. Though resistance to Bt products among insect species under field conditions has been rare, laboratory studies show that insects are capable of developing high levels of resistance to one ormore Cry proteins. Now it is generally agreed that 'high-dose/refuge strategy' is the most promising and practical approach to prolong the effectiveness of Bt toxins. Although manybiosafety concerns, ethical and moral issues exist, area under Bt transgenic crops is rapidly increasing and they are cultivated on more than 32 million hectares world over Even after reservation of European Union (EU) for acceptance of geneticaly modified (GM) crops, 6 out of 25 countries have already adopted Bt crops and many otherindustrial countries will adopt Bt transgenic crops in near future. While the modem biotechnology has been recognized to have a great potential for the promotion of human well-being, adoption

  11. Influences of Soil Fertility on Spatial Patterns of Aphis Gossypii Glover (Homoptera: Aphididae) Occurred in Bt-cotton Plants

    OpenAIRE

    Zhi-Qiang Tan; Tian-Cheng Ai; Xiao-Zhen Lu; Qing-Nian Cai; Cong Liu

    2012-01-01

    With the widespread planting of bacterium Bacillus thuringiensis (Bt)-cotton, non-target piercing-sucking insects such as Aphis gossypii Glover (Homoptera: Aphididae) have become the main hazard of cotton. Fertilization influences the distribution and population dynamics of aphid seriously. In this study, the effects of Nitrogen (N) and Phosphorus (P) on aphid population density were investigated on Bt-cotton; the combinational impacts of nitrogen and potassium (K) fertilizers on the distribu...

  12. MORAL HAZARD AND BT CORN REFUGE

    OpenAIRE

    Mitchell, Paul D.; Zhu, En (John)

    2003-01-01

    Using a principal-agent model, we find the optimal subsidy contract that induces grower compliance with Bt corn refuge requirements for managing insect resistance when asymmetric information exists concerning grower behavior. The optimal contract balances the cost of monitoring and the benefit of reducing the likelihood of insect resistance.

  13. DECOMPOSITION OF BT COTTON AND NON BT COTTON RESIDUES UNDER VARIED SOIL TYPES

    Directory of Open Access Journals (Sweden)

    Sujata Kumari

    2014-04-01

    Full Text Available Use of the insecticidal cry proteins from the bacterium, Bacillus thuringiensis (Bt in cotton has raised a number of concerns, including the ecological impact on soil ecosystems.Greenhouse study was conducted during the 2011 wet season (March to August at the Institute of Agricultural Sciences of Banaras Hindu University. It was carried out on three different soil orders that includedentisol, inceptisol and alfisol. Bt cotton (var.NCS-138 and its non-transgenic isoline (var.NCS-138 were grown until maturity. A no crop pot was maintained for all the three soil orders. The highest rate of decomposition was found in alluvial soil compared to black and red soils in 50 days after incorporation (DAI. Thereafter the rate of decomposition was slowed downby100 DAI and the constant rate of decomposition was found in 150 DAI. The rate of decomposition was higher in non Bt than Bt crop residues.

  14. Soil microbial biomass and root growth in Bt and non-Bt cotton

    Science.gov (United States)

    Tan, D. K. Y.; Broughton, K.; Knox, O. G.; Hulugalle, N. R.

    2012-04-01

    The introduction of transgenic Bacillus thuringiensis (Bt) cotton (Gossypium hirsutum L.) has had a substantial impact on pest management in the cotton industry. While there has been substantial research done on the impact of Bt on the above-ground parts of the cotton plant, less is known about the effect of Bt genes on below ground growth of cotton and soil microbial biomass. The aim of this research was to test the hypothesis that Bt [Sicot 80 BRF (Bollgard II Roundup Ready Flex®)] and non-Bt [Sicot 80 RRF (Roundup Ready Flex®)] transgenic cotton varieties differ in root growth and root turnover, carbon indices and microbial biomass. A field experiment was conducted in Narrabri, north-western NSW. The experimental layout was a randomised block design and used minirhizotron and core break and root washing methods to measure cotton root growth and turnover during the 2008/09 season. Root growth in the surface 0-0.1 m of the soil was measured using the core break and root washing methods, and that in the 0.1 to 1 m depth was measured with a minirhizotron and an I-CAP image capture system. These measurements were used to calculate root length per unit area, root carbon added to the soil through intra-seasonal root death, carbon in roots remaining at the end of the season and root carbon potentially added to the soil. Microbial biomass was also measured using the ninhydrin reactive N method. Root length densities and length per unit area of non-Bt cotton were greater than Bt cotton. There were no differences in root turnover between Bt and non-Bt cotton at 0-1 m soil depth, indicating that soil organic carbon stocks may not be affected by cotton variety. Cotton variety did not have an effect on soil microbial biomass. The results indicate that while there are differences in root morphology between Bt and non-Bt cotton, these do not change the carbon turnover dynamics in the soil.

  15. Biological activity of Bt proteins expressed in different structures of transgenic corn against Spodoptera frugiperda

    Directory of Open Access Journals (Sweden)

    Daniel Bernardi

    2016-06-01

    Full Text Available ABSTRACT: Spodoptera frugiperda (J. E. Smith is the main target pest of Bt corn technologies, such as YieldGard VT PRO(tm (Cry1A.105/Cry2Ab2 and PowerCore(tm (Cry1A.105/Cry2Ab2/Cry1F. In this study, it was evaluated the biological activity of Bt proteins expressed in different plant structures of YieldGard VT PRO(tm and PowerCore(tm corn against S. frugiperda . Complete mortality of S. frugiperda neonates was observed on leaf-disc of both Bt corn technologies. However, the mortality in silks and grains was lower than 50 and 6%, respectively. In addition, more than 49% of the surviving larvae in silks and grains completed the biological cycle. However, all life table parameters were negatively affected in insects that developed in silks and grains of both Bt corn events. In summary, the low biological activity of Bt proteins expressed on silks and grains of YieldGard VT PRO(tm and PowerCore(tm corn can contribute to the resistance evolution in S. frugiperda populations.

  16. Arthropod communities in the Bt and non Bt potato and maize fields

    Czech Academy of Sciences Publication Activity Database

    Habuštová, Oxana; Nedvěd, Oldřich; Sehnal, František

    Ivanka pri Dunaji : Ústav experimentálnej fytopatológie a entomológie SAV, 2002. s. 135-136. ISBN 80-224-0745-3. [Ochrana rastlín v III. miléniu. 01.10.2002-02.10.2002, Smolenice] R&D Projects: GA ČR GA522/02/1507 Keywords : Bt and non Bt plants * arthropods Subject RIV: EH - Ecology, Behaviour

  17. Practice Tests for the TOEFL iBT

    CERN Document Server

    Stirling, Bruce

    2012-01-01

    Practice Tests for the TOEFL iBT contains four TOEFL tests, with answer keys. Perfect for self-study and classrooms. Each TOEFL iBT Practice Test...* reflects the design of the official TOEFL internet-based test* tests academic English-language proficiency expected of university students in the United States, Canada, Australia, New Zealand, Ireland, Scotland and England* provides extra practice before you take the official TOEFL iBT* will help you identify those areas of academic English you need to improve for a higher TOEFL iBT score* will give you an unofficial, TOEFL iBT range score within

  18. Bt resistance in Australian insect pest species.

    Science.gov (United States)

    Downes, Sharon; Walsh, Tom; Tay, Wee Tek

    2016-06-01

    Bt cotton was initially deployed in Australia in the mid-1990s to control the polyphagous pest Helicoverpa armigera (Hübner) which was intractably resistant to synthetic chemistries. A conservative strategy was enforced and resistance to first generation single toxin technology was managed. A decade later, shortly after the release of dual toxin cotton, high baseline frequencies of alleles conferring resistance to one of its components prompted a reassessment of the thinking behind the potential risks to this technology. Several reviews detail the characteristics of this resistance and the nuances of deploying first and second generation Bt cotton in Australia. Here we explore recent advances and future possibilities to estimate Bt resistance in Australian pest species and define what we see as the critical data for enabling effective pre-emptive strategies. We also foreshadow the imminent deployment of three toxin (Cry1Ac, Cry2Ab, Vip3A) Bollgard 3 cotton, and examine aspects of resistance to its novel component, Vip3A, that we believe may impact on its stewardship. PMID:27436735

  19. A case to study population dynamics of bemisia tabaci and thrips tabaci on bt and non-bt cotton genotypes

    International Nuclear Information System (INIS)

    Studies were conducted to investigate the performance of eight bt and five non-bt cotton genotypes against whitefly and thrips and impact of abiotic factors on the population fluctuation of these sucking pests, at cotton research station, multan, during 2010 and 2011. The results exhibited that bt genotypes found more susceptible host for the whitefly and thirps than non-bt genotypes, during the course of years of study. Among bt genotypes, maximum and minimum temperature showed significant and positive effect on whitefly population whereas relative humidity exerted negative effect during 2010. During 2011, the effect of all the factors was non significant. On cumulative basis, there was positive correlation between population of whitefly and minimum temperature. But in case of non-bt, it has negative with maximum temperature whereas relative humidity had a positive effect on whitefly population. similar trend was observed for thrips population on bt varieties during both years but on non-bt varieties only minimum temperature exerted strong positive impact on thrips population. Hierarchical regression models for whitefly and thrips revealed that minimum temperature was the most important factor (Bt and non-Bt varieties). Maximum temperature was the major contributing factor for whitefly fluctuation on bt varieties during 2010. (author)

  20. Adaptive evolution of threonine deaminase in plant defense against insect herbivores

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales-Vigil, Eliana; Bianchetti, Christopher M.; Phillips, Jr., George N.; Howe, Gregg A. (MSU); (UW)

    2011-11-07

    Gene duplication is a major source of plant chemical diversity that mediates plant-herbivore interactions. There is little direct evidence, however, that novel chemical traits arising from gene duplication reduce herbivory. Higher plants use threonine deaminase (TD) to catalyze the dehydration of threonine (Thr) to {alpha}-ketobutyrate and ammonia as the committed step in the biosynthesis of isoleucine (Ile). Cultivated tomato and related Solanum species contain a duplicated TD paralog (TD2) that is coexpressed with a suite of genes involved in herbivore resistance. Analysis of TD2-deficient tomato lines showed that TD2 has a defensive function related to Thr catabolism in the gut of lepidopteran herbivores. During herbivory, the regulatory domain of TD2 is removed by proteolysis to generate a truncated protein (pTD2) that efficiently degrades Thr without being inhibited by Ile. We show that this proteolytic activation step occurs in the gut of lepidopteran but not coleopteran herbivores, and is catalyzed by a chymotrypsin-like protease of insect origin. Analysis of purified recombinant enzymes showed that TD2 is remarkably more resistant to proteolysis and high temperature than the ancestral TD1 isoform. The crystal structure of pTD2 provided evidence that electrostatic interactions constitute a stabilizing feature associated with adaptation of TD2 to the extreme environment of the lepidopteran gut. These findings demonstrate a role for gene duplication in the evolution of a plant defense that targets and co-opts herbivore digestive physiology.

  1. 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

  2. Field-evolved resistance to Bt maize by western corn rootworm.

    Directory of Open Access Journals (Sweden)

    Aaron J Gassmann

    Full Text Available BACKGROUND: Crops engineered to produce insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt are planted on millions of hectares annually, reducing the use of conventional insecticides and suppressing pests. However, the evolution of resistance could cut short these benefits. A primary pest targeted by Bt maize in the United States is the western corn rootworm Diabrotica virgifera virgifera (Coleoptera: Chrysomelidae. METHODOLOGY/PRINCIPAL FINDINGS: We report that fields identified by farmers as having severe rootworm feeding injury to Bt maize contained populations of western corn rootworm that displayed significantly higher survival on Cry3Bb1 maize in laboratory bioassays than did western corn rootworm from fields not associated with such feeding injury. In all cases, fields experiencing severe rootworm feeding contained Cry3Bb1 maize. Interviews with farmers indicated that Cry3Bb1 maize had been grown in those fields for at least three consecutive years. There was a significant positive correlation between the number of years Cry3Bb1 maize had been grown in a field and the survival of rootworm populations on Cry3Bb1 maize in bioassays. However, there was no significant correlation among populations for survival on Cry34/35Ab1 maize and Cry3Bb1 maize, suggesting a lack of cross resistance between these Bt toxins. CONCLUSIONS/SIGNIFICANCE: This is the first report of field-evolved resistance to a Bt toxin by the western corn rootworm and by any species of Coleoptera. Insufficient planting of refuges and non-recessive inheritance of resistance may have contributed to resistance. These results suggest that improvements in resistance management and a more integrated approach to the use of Bt crops may be necessary.

  3. Larval development of Spodoptera eridania (Cramer fed on leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 proteins and its non-Bt isoline

    Directory of Open Access Journals (Sweden)

    Orcial Ceolin Bortolotto

    2015-03-01

    Full Text Available This study aimed to evaluate, in controlled laboratory conditions (temperature of 25±2 °C, relative humidity of 60±10%, and 14/10 h L/D photoperiod, the larval development of Spodoptera eridania (Cramer, 1784 (Lepidoptera, Noctuidae fed with leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 insecticide proteins and its non-Bt isoline. Maize leaves triggered 100% of mortality on S. eridania larvae independently of being Bt or non-Bt plants. However, it was observed that in overall Bt maize (expressing a single or pyramided protein slightly affects the larval development of S. eridania, even under reduced leaf consumption. Therefore, these results showed that Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 can affect the larval development of S. eridania, although it is not a target pest of this plant; however, more research is needed to better understand this evidence. Finally, this study confirms that non-Bt maize leaves are unsuitable food source to S. eridania larvae, suggesting that they are not a potential pest in maize fields.

  4. 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. PMID:19961321

  5. Plant defense against herbivores: chemical aspects.

    Science.gov (United States)

    Mithöfer, Axel; Boland, Wilhelm

    2012-01-01

    Plants have evolved a plethora of different chemical defenses covering nearly all classes of (secondary) metabolites that represent a major barrier to herbivory: Some are constitutive; others are induced after attack. Many compounds act directly on the herbivore, whereas others act indirectly via the attraction of organisms from other trophic levels that, in turn, protect the plant. An enormous diversity of plant (bio)chemicals are toxic, repellent, or antinutritive for herbivores of all types. Examples include cyanogenic glycosides, glucosinolates, alkaloids, and terpenoids; others are macromolecules and comprise latex or proteinase inhibitors. Their modes of action include membrane disruption, inhibition of nutrient and ion transport, inhibition of signal transduction processes, inhibition of metabolism, or disruption of the hormonal control of physiological processes. Recognizing the herbivore challenge and precise timing of plant activities as well as the adaptive modulation of the plants' metabolism is important so that metabolites and energy may be efficiently allocated to defensive activities. PMID:22404468

  6. The Cry1Ab Protein Has Minor Effects on the Arbuscular Mycorrhizal Fungal Communities after Five Seasons of Continuous Bt Maize Cultivation

    Science.gov (United States)

    Shu, Yinghua; Zhang, Yanyan; Feng, Yuanjiao; Wang, Jianwu

    2015-01-01

    The cultivation of genetically modified plants (GMP) has raised concerns regarding the plants’ ecological safety. A greenhouse experiment was conducted to assess the impact of five seasons of continuous Bt (Bacillus thuringiensis) maize cultivation on the colonisation and community structure of the non-target organisms arbuscular mycorrhizal fungi (AMF) in the maize roots, bulk soils and rhizospheric soils using the terminal restriction fragment length polymorphism (T-RFLP) analysis of the 28S ribosomal DNA and sequencing methods. AMF colonisation was significantly higher in the two Bt maize lines that express Cry1Ab, 5422Bt1 (event Bt11) and 5422CBCL (MON810) than in the non-Bt isoline 5422. No significant differences were observed in the diversity of the AMF community between the roots, bulk soils and rhizospheric soils of the Bt and non-Bt maize cultivars. The AMF genus Glomus was dominant in most of the samples, as detected by DNA sequencing. A clustering analysis based on the DNA sequence data suggested that the sample types (i.e., the samples from the roots, bulk soils or rhizospheric soils) might have greater influence on the AMF community phylotypes than the maize cultivars. This study indicated that the Cry1Ab protein has minor effects on the AMF communities after five seasons of continuous Bt maize cultivation. PMID:26717324

  7. The Cry1Ab Protein Has Minor Effects on the Arbuscular Mycorrhizal Fungal Communities after Five Seasons of Continuous Bt Maize Cultivation.

    Science.gov (United States)

    Zeng, Huilan; Tan, Fengxiao; Shu, Yinghua; Zhang, Yanyan; Feng, Yuanjiao; Wang, Jianwu

    2015-01-01

    The cultivation of genetically modified plants (GMP) has raised concerns regarding the plants' ecological safety. A greenhouse experiment was conducted to assess the impact of five seasons of continuous Bt (Bacillus thuringiensis) maize cultivation on the colonisation and community structure of the non-target organisms arbuscular mycorrhizal fungi (AMF) in the maize roots, bulk soils and rhizospheric soils using the terminal restriction fragment length polymorphism (T-RFLP) analysis of the 28S ribosomal DNA and sequencing methods. AMF colonisation was significantly higher in the two Bt maize lines that express Cry1Ab, 5422Bt1 (event Bt11) and 5422CBCL (MON810) than in the non-Bt isoline 5422. No significant differences were observed in the diversity of the AMF community between the roots, bulk soils and rhizospheric soils of the Bt and non-Bt maize cultivars. The AMF genus Glomus was dominant in most of the samples, as detected by DNA sequencing. A clustering analysis based on the DNA sequence data suggested that the sample types (i.e., the samples from the roots, bulk soils or rhizospheric soils) might have greater influence on the AMF community phylotypes than the maize cultivars. This study indicated that the Cry1Ab protein has minor effects on the AMF communities after five seasons of continuous Bt maize cultivation. PMID:26717324

  8. 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

  9. Solving the Problem of Sustainable Use of Bt Crops

    OpenAIRE

    Dun, Zhe; Mitchell, Paul D.

    2011-01-01

    Transgenic plants producing insecticidal protein derived from Bacillus thuringiensis (Bt) have been widely adopted since their commercial introduction in 1996. The widespread adoption of such plants has reduced use of conventional insecticides while attaining yield gains, thus providing economic, environmental and human health benefits. However, the benefits from Bt crops will be reduced or even eliminated if pests develop resistance to these toxins so that Bt crops are less or no longer effe...

  10. 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

  11. 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...

  12. Testing pollen of single and stacked insect-resistant Bt-maize on in vitro reared honey bee larvae.

    Science.gov (United States)

    Hendriksma, Harmen P; Härtel, Stephan; Steffan-Dewenter, Ingolf

    2011-01-01

    The ecologically and economic important honey bee (Apis mellifera) is a key non-target arthropod species in environmental risk assessment (ERA) of genetically modified (GM) crops. Honey bee larvae are directly exposed to transgenic products by the consumption of GM pollen. But most ERA studies only consider responses of adult bees, although Bt-proteins primarily affect the larval phases of target organisms. We adopted an in vitro larvae rearing system, to assess lethal and sublethal effects of Bt-pollen consumption in a standardized eco-toxicological bioassay. The effects of pollen from two Bt-maize cultivars, one expressing a single and the other a total of three Bt-proteins, on the survival and prepupae weight of honey bee larvae were analyzed. The control treatments included pollen from three non-transgenic maize varieties and of Heliconia rostrata. Three days old larvae were fed the realistic exposure dose of 2 mg pollen within the semi-artificial diet. The larvae were monitored over 120 h, until the prepupal stage, where larvae terminate feeding and growing. Neither single nor stacked Bt-maize pollen showed an adverse effect on larval survival and the prepupal weight. In contrast, feeding of H. rostrata pollen caused significant toxic effects. The results of this study indicate that pollen of the tested Bt-varieties does not harm the development of in vitro reared A. mellifera larvae. To sustain the ecosystem service of pollination, Bt-impact on A. mellifera should always be a crucial part of regulatory biosafety assessments. We suggest that our approach of feeding GM pollen on in vitro reared honey bee larvae is well suited of becoming a standard bioassay in regulatory risk assessments schemes of GM crops. PMID:22194811

  13. Testing pollen of single and stacked insect-resistant Bt-maize on in vitro reared honey bee larvae.

    Directory of Open Access Journals (Sweden)

    Harmen P Hendriksma

    Full Text Available The ecologically and economic important honey bee (Apis mellifera is a key non-target arthropod species in environmental risk assessment (ERA of genetically modified (GM crops. Honey bee larvae are directly exposed to transgenic products by the consumption of GM pollen. But most ERA studies only consider responses of adult bees, although Bt-proteins primarily affect the larval phases of target organisms. We adopted an in vitro larvae rearing system, to assess lethal and sublethal effects of Bt-pollen consumption in a standardized eco-toxicological bioassay. The effects of pollen from two Bt-maize cultivars, one expressing a single and the other a total of three Bt-proteins, on the survival and prepupae weight of honey bee larvae were analyzed. The control treatments included pollen from three non-transgenic maize varieties and of Heliconia rostrata. Three days old larvae were fed the realistic exposure dose of 2 mg pollen within the semi-artificial diet. The larvae were monitored over 120 h, until the prepupal stage, where larvae terminate feeding and growing. Neither single nor stacked Bt-maize pollen showed an adverse effect on larval survival and the prepupal weight. In contrast, feeding of H. rostrata pollen caused significant toxic effects. The results of this study indicate that pollen of the tested Bt-varieties does not harm the development of in vitro reared A. mellifera larvae. To sustain the ecosystem service of pollination, Bt-impact on A. mellifera should always be a crucial part of regulatory biosafety assessments. We suggest that our approach of feeding GM pollen on in vitro reared honey bee larvae is well suited of becoming a standard bioassay in regulatory risk assessments schemes of GM crops.

  14. Development and reproduction of Spodoptera eridania (Lepidoptera: Noctuidae) and its egg parasitoid Telenomus remus (Hymenoptera: Platygastridae) on the genetically modified soybean (Bt) MON 87701×MON 89788.

    Science.gov (United States)

    Bortolotto, O C; Silva, G V; de Freitas Bueno, A; Pomari, A F; Martinelli, S; Head, G P; Carvalho, R A; Barbosa, G C

    2014-12-01

    Genetically modified crops with insect resistance genes from Bacillus thuringiensis Berliner (Bt-plants) are increasingly being cultivated worldwide. Therefore, it is critical to improve our knowledge of their direct or indirect impact not only on target pests but also on non-target arthropods. Hence, this study evaluates comparative leaf consumption and performance of Spodoptera eridania (Cramer), a species that is tolerant of the Cry1Ac protein, fed with Bt soybean, MON 87701×MON 89788 or its near [corrected] non-Bt isoline. Using this species as a model, we assessed [corrected] the comparative performance of the egg parasitoid Telenomus remus Nixon on eggs of S. eridania produced from individuals that fed on these two soybean genotypes [corrected] as larvae. Results showed that Bt soybean did not affect pest foliage consumption, but did reduce larvel duration by two days despite larvae in both treatments having six instars. Nevertheless, survival of S. eridania larvae, pupal weight, sex ratio, fecundity and longevity of female moths, and egg viability did not differ between Bt and non-Bt soybeans. Adult longevity of S. eridania males was increased when caterpillars were fed with Bt soybean versus the near isoline. No adverse effects of this technology were observed for the egg parasitoid T. remus. [corrected]. PMID:25248849

  15. The development and status of Bt rice in China.

    Science.gov (United States)

    Li, Yunhe; Hallerman, Eric M; Liu, Qingsong; Wu, Kongming; Peng, Yufa

    2016-03-01

    Multiple lines of transgenic rice expressing insecticidal genes from the bacterium Bacillus thuringiensis (Bt) have been developed in China, posing the prospect of increases in production with decreased application of pesticides. We explore the issues facing adoption of Bt rice for commercial production in China. A body of safety assessment work on Bt rice has shown that Bt rice poses a negligible risk to the environment and that Bt rice products are as safe as non-Bt control rice products as food. China has a relatively well-developed regulatory system for risk assessment and management of genetically modified (GM) plants; however, decision-making regarding approval of commercial production has become politicized, and two Bt rice lines that otherwise were ready have not been allowed to enter the Chinese agricultural system. We predict that Chinese farmers would value the prospect of increased yield with decreased use of pesticide and would readily adopt production of Bt rice. That Bt rice lines may not be commercialized in the near future we attribute to social pressures, largely due to the low level of understanding and acceptance of GM crops by Chinese consumers. Hence, enhancing communication of GM crop science-related issues to the public is an important, unmet need. While the dynamics of each issue are particular to China, they typify those in many countries where adoption of GM crops has been not been rapid; hence, the assessment of these dynamics might inform resolution of these issues in other countries. PMID:26369652

  16. TMD factorization and evolution at large $b_T$

    CERN Document Server

    Collins, John

    2015-01-01

    In using transverse-momentum-dependent (TMD) parton densities and fragmentation functions, important non-perturbative information is at large transverse position $b_T$. This concerns both the TMD functions and their evolution. Fits to high energy data tend to predict too rapid evolution when extrapolated to low energies where larger values of $b_T$ dominate. I summarize a new analysis of the issues. It results in a proposal for much weaker $b_T$ dependence at large $b_T$ for the evolution kernel, while preserving the accuracy of the existing fits. The results are particularly important for using transverse-spin-dependent functions like the Sivers function.

  17. TMD factorization and evolution at large $b_T$

    Energy Technology Data Exchange (ETDEWEB)

    Collins, John [Pennsylvania State Univ., University Park, PA (United States); Rogers, Ted [Thomas Jefferson National Accelerator Facility (TJNAF), Newport News, VA (United States); Old Dominion Univ., Norfolk, VA (United States)

    2015-07-20

    In using transverse-momentum-dependent (TMD) parton densities and fragmentation functions, important non-perturbative information is at large transverse position $b_T$. This concerns both the TMD functions and their evolution. Fits to high energy data tend to predict too rapid evolution when extrapolated to low energies where larger values of $b_T$ dominate. I summarize a new analysis of the issues. It results in a proposal for much weaker $b_T$ dependence at large $b_T$ for the evolution kernel, while preserving the accuracy of the existing fits. The results are particularly important for using transverse-spin-dependent functions like the Sivers function.

  18. 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....

  19. Bt Crops and Invertebrate Non-target Effects – Revisited

    Science.gov (United States)

    Crops that have been transgenically engineered for resistance to select insect pests by the use of genes from a common soil bacteria (Bacillus thuringiensis) were grown on about 42 million hectares in 20 countries in 2007. Debate continues on the environmental risk of these crops. This short artic...

  20. ASSESSING POSSIBLE ECOLOGICAL RISKS OF GENETICALLY MODIFIED CROPS: GENE EXPRESSION ASSAYS AND GENETIC MONITORING OF NON-TARGET ORGANISMS

    Science.gov (United States)

    Widespread planting of genetically modified crops with the Bt transgene pesticide has led to concern over non-target effects of Bt compounds in agroecosystems. While some research suggests that non-target organisms exposed to Bt toxin exhibit reduced fecundity and increased morta...

  1. MONARCH BUTTERFLIES AND BT CORN POLLEN: PHENOLOGY AND MOVEMENT CONSIDERATIONS

    Science.gov (United States)

    Proven methods of risk assessment were used by a consortium of scientists to investigate the potential impact of Bt corn pollen on the monarch butterfly. Toxicity of Bt corn pollen and larval exposure to harmful levels of pollen were investigated. Research indicates that the potential risk to monarc...

  2. MONARCH BUTTERFLIES AND BT CORN: REPLACING HOOPLA WITH SCIENCE

    Science.gov (United States)

    Proven methods of risk assessment were used by a consortium of scientists to investigate the potential impact of Bacillus thuringiensis (Bt) corn pollen on the monarch butterfly. Toxicity of Bt corn pollen and larval exposure to harmful levels of pollen were investigated. Research indicates that the...

  3. Event-specific plasmid standards and real-time PCR methods for transgenic Bt11, Bt176, and GA21 maize and transgenic GT73 canola.

    Science.gov (United States)

    Taverniers, Isabel; Windels, Pieter; Vaïtilingom, Marc; Milcamps, Anne; Van Bockstaele, Erik; Van den Eede, Guy; De Loose, Marc

    2005-04-20

    Since the 18th of April 2004, two new regulations, EC/1829/2003 on genetically modified food and feed products and EC/1830/2003 on traceability and labeling of GMOs, are in force in the EU. This new, comprehensive regulatory framework emphasizes the need of an adequate tracing system. Unique identifiers, such as the transgene genome junction region or a specific rearrangement within the transgene DNA, should form the basis of such a tracing system. In this study, we describe the development of event-specific tracing systems for transgenic maize lines Bt11, Bt176, and GA21 and for canola event GT73. Molecular characterization of the transgene loci enabled us to clone an event-specific sequence into a plasmid vector, to be used as a marker, and to develop line-specific primers. Primer specificity was tested through qualitative PCRs and dissociation curve analysis in SYBR Green I real-time PCRs. The primers were then combined with event-specific TaqMan probes in quantitative real-time PCRs. Calibration curves were set up both with genomic DNA samples and the newly synthesized plasmid DNA markers. It is shown that cloned plasmid GMO target sequences are perfectly suitable as unique identifiers and quantitative calibrators. Together with an event-specific primer pair and a highly specific TaqMan probe, the plasmid markers form crucial components of a unique and straighforward tracing system for Bt11, Bt176, and GA21 maize and GT73 canola events. PMID:15826057

  4. When herbivores eat predators: predatory insects effectively avoid incidental ingestion by mammalian herbivores.

    Science.gov (United States)

    Ben-Ari, Matan; Inbar, Moshe

    2013-01-01

    The direct trophic links between mammalian herbivores and plant-dwelling insects have been practically ignored. Insects are ubiquitous on plants consumed by mammalian herbivores and are thus likely to face the danger of being incidentally ingested by a grazing mammal. A few studies have shown that some herbivorous hemipterans are able to avoid this peril by dropping to the ground upon detecting the heat and humidity on the mammal's breath. We hypothesized that if this risk affects the entire plant-dwelling insect community, other insects that share this habitat are expected to develop similar escape mechanisms. We assessed the ability of three species (adults and larvae) of coccinellid beetles, important aphid predators, to avoid incidental ingestion. Both larvae and adults were able to avoid incidental ingestion effectively by goats by dropping to the ground, demonstrating the importance of this behavior in grazed habitats. Remarkably, all adult beetles escaped by dropping off the plant and none used their functional wings to fly away. In controlled laboratory experiments, we found that human breath caused 60-80% of the beetles to drop. The most important component of mammalian herbivore breath in inducing adult beetles and larvae to drop was the combination of heat and humidity. The fact that the mechanism of dropping in response to mammalian breath developed in distinct insect orders and disparate life stages accentuates the importance of the direct influence of mammalian herbivores on plant-dwelling insects. This direct interaction should be given its due place when discussing trophic interactions. PMID:23424674

  5. Biosafety assessment of transgenic Bt cotton on model animals

    Directory of Open Access Journals (Sweden)

    Sadia Bano

    2016-05-01

    Full Text Available Abstract Background: To know the effects of transgenic crops on soil microorganisms, animals and other expected hazards due to the introduction of GM crops into the environment is critical both scientifically and environmentally. The work was conducted to study the effect of insecticidal Bt protein on Rats and Earthworms. Methods: For this purpose, animals like rat and soil organisms like Earthworm were selected. Rats were selected on the basis of its 95% homology on genomic, cellular and enzymatic level with human while earthworm were preferred on the basis of their direct contact with soil to evaluate the impact of Bt (Cry1AC crop field soil on earthworm, secreted by root exudates of Bt cotton. Several physical, molecular, biochemical and histological analyses were performed on both Rats/Earthworms fed on standard diet (control group as well containing Bt protein (experimental group. Results: Molecular analyses such as immune Dot blot, SDS-PAGE, ELISA and PCR, confirmed the absence of Cry1Ac protein in blood and urine samples of rats, which were fed with Bt protein in their diet. Furthermore, histological studies showed that there was no difference in cellular architecture in liver, heart, kidney and intestine of Bt and non-Bt diet fed rats. To see the effect of Bt on earthworm two different groups were studied, one with transgenic plant field soil supplemented with grinded leaves of cotton and second group with non-Bt field soil. Conclusions: No lethal effects of transgenic Bt protein on the survival of earthworm and rats were observed. Bradford assay, Dipstick assay ELISA demonstrated the absence of Cry1Ac protein in the mid-gut epithelial tissue of earthworm. The results of present study will be helpful in successful deployment and commercial release of genetically modified crop in Pakistan.

  6. The effects of high temperature level on square Bt protein concentration of Bt cotton

    Institute of Scientific and Technical Information of China (English)

    WANG Jun; CHEN Yuan; YAO Meng-hao; LI Yuan; WEN Yu-jin; ZHANG Xiang; CHEN De-hua

    2015-01-01

    Higher bol worm survival rates were detected after high temperature presented during square period in Bt cotton. The objective of this study was to investigate the effects of high temperature level on the Bt efifcacy of two different types of Bt cotton cultivars at squaring stage. During the 2011 to 2013 cotton growth seasons, high temperature treatments ranged from 34 to 44°C in climate chambers, and ifeld experiments under high temperature weather with various temperature levels were conducted to investigate the effects of the high temperature level on square Bt protein concentration and nitrogen metabolism. The climate chamber experiments showed that the square insecticidal protein contents reduced after 24 h elevated temperature treatments for both cultivars, whereas signiifcant declines of the square insecticidal protein contents were detected at temperature >38°C, and only slightly numerical reductions were observed when temperature below 38°C. Similar high temperature responses were also observed at the two ifeld experimental sites in 2013. Correspondingly, high temperature below 38°C seems have little effect on the square amino acid concentrations, soluble protein contents, glutam-ic-pyruvic transaminase (GPT) and glutamic-oxalacetic transaminase (GOT) activities as wel as protease and peptidase activities; however, when the temperature was above 38°C, reduced soluble protein contents, enhanced amino acid con-centrations, decreased GPT and GOT activities, bolstered protease and peptidase activities in square were detected. In general, the higher the temperature is (>38°C), the larger the changes for the above compound contents and key enzymes activities of the square protein cycle. The ifndings indicated that the unstable insect resistance of the square was related to high temperature level during square stage.

  7. Do Sesamia nonagrioides (Lepidoptera; Noctuidae) gravid females discriminate between Bt or multivitamin corn varieties? Role of olfactory and visual cues.

    Science.gov (United States)

    Cruz, Diego; Eizaguirre, Matilde

    2015-01-01

    The Mediterranean corn borer, Sesamia nonagrioides Lefèbvre, is a key pest of corn and a main target of Bacillus thuringiensis (Bt) corn in Northeast Spain. Trends for future biotechnology crops indicate that Bt, non-Bt, and stacked corn varieties with metabolic pathways for vitamin-increased traits could coexist in same region. Knowledge of the oviposition response of gravid females of S. nonagrioides to these different varieties could be extremely important for managing strategies aimed for delaying resistance development. In dual-choice assays, we examined the host preference of gravid females of S. nonagrioides for four corn varieties: a new transgenic corn with increased vitamin levels, its near isogenic counterpart (M37W), a Bt corn plant, and its near isogenic counterpart. Olfactory cues were the predominant ones when gravid females looked for a suitable host to lay eggs, and no synergistic effects were observed when both visual and olfactory cues were present. When the plant was visible, the females preferred the odors emitted by the nontransgenic to its multivitamin transgenic counterpart and when they only could detect the volatiles they also preferred the nontransgenic M37W variety to the Bt corn variety. If gravid females are less attracted to corn with an increased level of vitamins, this could impact insect resistance management and the value of refuge plants, if such traits are stacked with an insect resistance trait. PMID:25843586

  8. Microarray detection and qPCR screening of potential biomarkers of Folsomia candida (Collembola: Isotomidae) exposed to Bt proteins (Cry1Ab and Cry1Ac)

    International Nuclear Information System (INIS)

    The impact of Bt proteins on non-target arthropods is less understood than their effects on target organisms where the mechanism of toxic action is known. Here, we report the effects of two Bt proteins, Cry1Ab and Cry1Ac, on gene expression in the non-target collembolan, Folsomia candida. A customized microarray was used to study gene expression in F. candida specimens that were exposed to Cry1Ab and Cry1Ac. All selected transcripts were subsequently confirmed by qPCR. Eleven transcripts were finally verified, and three of them were annotated. The responses of all eleven transcripts were tested in specimens for both Cry1Ab and Cry1Ac at a series of concentrations. These transcripts were separated into two and three groups for Cry1Ab and Cry1Ac, respectively, depend on their expression levels. However, those eleven transcripts did not respond to the Bt proteins in Bt-rice residues. -- Highlights: • We examined the effects of Bt proteins on gene expression of Folsomia candida. • Eleven transcripts were up-regulated by Bt proteins (Cry1Ab and Cry1Ac). • Only three of the eleven transcripts were annotated. • The responses of 11 transcripts were tested on both Cry1Ab and Cry1Ac. • These transcripts did not respond to the Bt proteins in Bt-rice residues. -- Eleven potential molecular biomarkers of Folsomia candida to Cry1Ab and Cry1Ac were screened by microarray and qPCR analysis

  9. Bt rice expressing Cry2Aa does not harm Cyrtorhinus lividipennis, a main predator of the nontarget herbivore Nilapavarta lugens.

    Directory of Open Access Journals (Sweden)

    Yu Han

    Full Text Available T2A-1 is a newly developed transgenic rice that expresses a synthesized cry2Aa gene driven by the maize ubiquitin promoter. T2A-1 exhibits high resistance against lepidopteran pests of rice. The brown planthopper, Nilapavarta lugens (Stål, is a main nontarget sap-sucking insect pest of rice, and Cyrtorhinus lividipennis (Reuter is the major predator of the eggs and young nymphs of planthoppers. As C. lividipennis may expose to the Cry2Aa protein via N. lugens, it is therefore essential to assess the potential effects of transgenic cry2Aa rice on this predator. In the present study, three experiments were conducted to evaluate the ecological risk of transgenic cry2Aa rice to C. lividipennis: (1 a direct feeding experiment in which C. lividipennis was fed an artificial diet containing Cry2Aa at the dose of 10-time higher than that it may encounter in the realistic field condition; (2 a tritrophic experiment in which the Cry2Aa protein was delivered to C. lividipennis indirectly through prey eggs or nymphs; (3 a realistic field experiment in which the population dynamics of C. lividipennis were investigated using vacuum-suction. Both direct exposure to elevated doses of the Cry2Aa protein and prey-mediated exposure to realistic doses of the protein did not result in significant detrimental effects on the development, survival, female ratio and body weight of C. lividipennis. No significant differences in population density and population dynamics were observed between C. lividipennis in transgenic cry2Aa and nontransgenic rice fields. It may be concluded that transgenic cry2Aa rice had no detrimental effects on C. lividipennis. This study represents the first report of an assessment continuum for the effects of transgenic cry2Aa rice on C. lividipennis.

  10. Can inducible resistance in plants cause herbivore aggregations? Spatial patterns in an inducible plant/herbivore model.

    Science.gov (United States)

    Anderson, Kurt E; Inouye, Brian D; Underwood, Nora

    2015-10-01

    Many theories regarding the evolution of inducible resistance in plants have an implicit spatial component, but most relevant population dynamic studies ignore spatial dynamics. We examined a spatially explicit model of plant inducible resistance and herbivore population dynamics to explore how realistic features of resistance and herbivore responses influence spatial patterning. Both transient and persistent spatial patterns developed in all models examined, where patterns manifested as wave-like aggregations of herbivores and variation in induction levels. Patterns arose when herbivores moved away from highly induced plants, there was a lag between damage and deployment of induced resistance, and the relationship between herbivore density and strength of the induction response had a sigmoid shape. These mechanisms influenced pattern formation regardless of the assumed functional relationship between resistance and herbivore recruitment and mortality. However, in models where induction affected herbivore mortality, large-scale herbivore population cycles driven by the mortality response often co-occurred with smaller scale spatial patterns driven by herbivore movement. When the mortality effect dominated, however, spatial pattern formation was completely replaced by spatially synchronized herbivore population cycles. Our results present a new type of ecological pattern formation driven by induced trait variation, consumer behavior, and time delays that has broad implications for the community and evolutionary ecology of plant defenses. PMID:26649396

  11. Impact of violated high-dose refuge assumptions on evolution of Bt resistance.

    Science.gov (United States)

    Campagne, Pascal; Smouse, Peter E; Pasquet, Rémy; Silvain, Jean-François; Le Ru, Bruno; Van den Berg, Johnnie

    2016-04-01

    Transgenic crops expressing Bacillus thuringiensis (Bt) toxins have been widely and successfully deployed for the control of target pests, while allowing a substantial reduction in insecticide use. The evolution of resistance (a heritable decrease in susceptibility to Bt toxins) can pose a threat to sustained control of target pests, but a high-dose refuge (HDR) management strategy has been key to delaying countervailing evolution of Bt resistance. The HDR strategy relies on the mating frequency between susceptible and resistant individuals, so either partial dominance of resistant alleles or nonrandom mating in the pest population itself could elevate the pace of resistance evolution. Using classic Wright-Fisher genetic models, we investigated the impact of deviations from standard refuge model assumptions on resistance evolution in the pest populations. We show that when Bt selection is strong, even deviations from random mating and/or strictly recessive resistance that are below the threshold of detection can yield dramatic increases in the pace of resistance evolution. Resistance evolution is hastened whenever the order of magnitude of model violations exceeds the initial frequency of resistant alleles. We also show that the existence of a fitness cost for resistant individuals on the refuge crop cannot easily overcome the effect of violated HDR assumptions. We propose a parametrically explicit framework that enables both comparison of various field situations and model inference. Using this model, we propose novel empiric estimators of the pace of resistance evolution (and time to loss of control), whose simple calculation relies on the observed change in resistance allele frequency. PMID:27099624

  12. Distribuição espacial de Aphis gossypii (Glover (Hemiptera, Aphididae e Bemisia tabaci (Gennadius biótipo B (Hemiptera, Aleyrodidae em algodoeiro Bt e não-Bt Spatial distribution of Aphis gossypii (Glover (Hemiptera, Aphididae and Bemisia tabaci (Gennadius biotype B (Hemiptera, Aleyrodidae on Bt and non-Bt cotton

    Directory of Open Access Journals (Sweden)

    Tatiana Rojas Rodrigues

    2010-03-01

    improving the sampling techniques and revealing differences in the behavior of non-target species between both cultivars. So, this experiment aimed to investigate the spatial distribution pattern of those species on the conventional non-Bt cotton crop, compared to the Bt cultivar. The samplings took place in two areas of 5.000 m² each, where it was done 14 evaluations counting adults of white-flies and colonies of aphids. The aggregation indexes (variance/mean rate, index of Morisita and Exponent k of the Negative Binomial Distribution were calculated and accomplished the fitness tests of the individuals' numeric classes found and expected to the theoretical distributions of frequency (Poisson, Negative Binomial and Positive Binomial. Those analyses showed that in both cultivars, the spatial distribution of B. tabaci fitted to negative binomial distribution throughout the study period, indicating that the transgenic cultivar did not influence the pattern of aggregate distribution of this insect. With respect to the analysis for A. gossypii, the aggregation indexes showed aggregated distribution in both cultivars, but the distributions of frequency pointed to the occurrence of aggregate distribution only on conventional cotton, since there was no adjustment to the data on Bt crop. This indicates that Bt cotton has altered the aphids normal pattern of dispersion in the crop.

  13. Bt-CoV HKU3 PCR/Sequencing Primers

    OpenAIRE

    sprotocols

    2014-01-01

    Authors: Rachel Graham ### Abstract This protocol details the primers and conditions used for forward and reverse PCR amplification and sequencing of Bt-CoV HKU3 genomes. ### Introduction This protocol details the steps, reagents, and conditions required to sequence Bt-CoV HKU3 genomes in the forward and reverse directions. The protocol begins with the RT-PCR step, assuming that BtCoV HKU3 RNA purified using a standard procedure (i.e., TRIzol extraction) has already been perfo...

  14. Bt-CoV HKU5 PCR/Sequencing Primers

    OpenAIRE

    sprotocols

    2014-01-01

    Authors: Rachel Graham ### Abstract This protocol details the primers and conditions used for forward and reverse PCR amplification and sequencing of Bt-CoV HKU5 genomes. ### Introduction This protocol details the steps, reagents, and conditions required to sequence Bt-CoV HKU5 genomes in the forward and reverse directions. The protocol begins with the RT-PCR step, assuming that BtCoV HKU5 RNA purified using a standard procedure (i.e., TRIzol extraction) has already been perfo...

  15. Study on radioimmunoassay of Bt Cry1Ac protein

    International Nuclear Information System (INIS)

    Bt Cry1Ac protein was extracted from incubation of Bacillus thuringiensis HD-73, and cutting into more specific protein segment with high insect-resistance. High-affinity multi-colonial antibodies of Bt Cry1 Ac protein were obtained after injected it into New Zealand rabbits. By 125I labeling of Bt Cry1 Ac protein, a RIA kit was established. In this method, centrifuge for separation was not necessary due to the use of magnetic micro-particle and the specifications of the kit were found equal to those of imported ELISA. (authors)

  16. Can other host species of cotton bollworm be non-Bt refuges to prolong the effectiveness of Bt-cotton?

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The potential ecological risks of Bacillus thurigiensis (Bt) insecticides and Bt-crops have caused increasing concern since their commercial release in the field,among which pests' resistance to Bt-crops is the major ecological risk. Refuge tactic, which can produce sensitive populations, has proved to be a key and sound resistance management strategy in USA and Australia; however, no tactics have been performed in China where Bt-cotton is mostly planted with other host crops of cotton bollworm.Genetic variation and gene flow among different host populations of the cotton bollworm Helicoverpa armigera were analyzed using PCR fingerprinting method. The results show that maize and castor-oil plant, as well as cotton can take effect as refuges to prevent resistance of cotton bollworm to Bt-cotton, while peanut and sesame are not as suitable for planting with Bt-cotton as refuges in the field as low gene flow was detected among populations on peanut, sesame and Bt cotton.

  17. Suppressing Resistance to Bt Cotton with Sterile Insect Releases

    International Nuclear Information System (INIS)

    Genetically engineered crops that produce insecticidal toxins from Bacillus thuringiensis (Bt) are grown widely for pest control. However, insect adaptation can reduce the toxins' efficacy. The predominant strategy for delaying pest resistance to Bt crops requires refuges of non-Bt host plants to provide susceptible insects to mate with resistant insects. Variable farmer compliance is one of the limitations of this approach. Here we report the benefits of an alternative strategy where sterile insects are released to mate with resistant insects and refuges are scarce or absent. Computer simulations show that this approach works in principle against pests with recessive or dominant inheritance of resistance. During a largescale, four-year field deployment of this strategy in Arizona, resistance of pink bollworm (Pectinophora gossypiella) to Bt cotton did not increase. A multitactic eradication program that included the release of sterile moths reduced pink bollworm abundance by >99%, while eliminating insecticide sprays against this key invasive pest. (author)

  18. Current trends in Bt crops and their fate on associated microbial community dynamics: a review.

    Science.gov (United States)

    Singh, Amit Kishore; Dubey, Suresh Kumar

    2016-05-01

    Cry protein expressing insect-resistant trait is mostly deployed to control major devastating pests and minimize reliance on the conventional pesticides. However, the ethical and environmental issues are the major constraints in their acceptance, and consequently, the cultivation of genetically modified (GM) crops has invited intense debate. Since root exudates of Bacillus thuringiensis (Bt) crops harbor the insecticidal protein, there is a growing concern about the release and accumulation of soil-adsorbed Cry proteins and their impact on non-target microorganisms and soil microbial processes. This review pertains to reports from the laboratory studies and field trials to assess the Bt toxin proteins in soil microbes and the processes determining the soil quality in conjunction with the existing hypothesis and molecular approaches to elucidate the risk posed by the GM crops. Ecological perturbations hinder the risk aspect of soil microbiota in response to GM crops. Therefore, extensive research based on in vivo and interpretation of results using high-throughput techniques such as NGS on risk assessment are imperative to evaluate the impact of Bt crops to resolve the controversy related to their commercialization. But more studies are needed on the risk associated with stacked traits. Such studies would strengthen our knowledge about the plant-microbe interactions. PMID:26560114

  19. The Adoption of Bt-Maize - An Econometric Analysis

    OpenAIRE

    Consmuller, Nicola; Beckmann, Volker; Petrick, Martin

    2009-01-01

    In this study, we theoretically and empirically investigate the determinants of Bt maize adoption in German regions. Specifically, we ask how the regulatory framework, the farm structures as well as the socio-political environment of GM expansion in Germany have influenced regional adoption rates. Following a description of the relevant legal and economic framework in Germany, we develop theoretical hypotheses concerning regional variation in Bt-maize adoption and test them econometrically wi...

  20. Can Conventional Crop Producers Also Benefit From Bt Technology?

    OpenAIRE

    Dun, Zhe; Mitchell, Paul D.

    2011-01-01

    Transgenic plants producing insecticidal protein derived from Bacillus thuringiensis (Bt) have been widely adopted since their commercial introduction in 1996. In 2009, 25 countries planted 134 million ha of transgenic crops. The widespread adoption of such plants has reduced use of conventional insecticides while attaining yield gains, thus providing economic, environmental and human health benefits. Because of Bt crops’ high pest control efficacy, there is concern that pests will develop re...

  1. Distribution and Metabolism of Bt-Cry1Ac Toxin in Tissues and Organs of the Cotton Bollworm, Helicoverpa armigera

    Directory of Open Access Journals (Sweden)

    Zhuoya Zhao

    2016-07-01

    Full Text Available Crystal (Cry proteins derived from Bacillus thuringiensis (Bt have been widely used in transgenic crops due to their toxicity against insect pests. However, the distribution and metabolism of these toxins in insect tissues and organs have remained obscure because the target insects do not ingest much toxin. In this study, several Cry1Ac-resistant strains of Helicoverpa armigera, fed artificial diets containing high doses of Cry1Ac toxin, were used to investigate the distribution and metabolism of Cry1Ac in their bodies. Cry1Ac was only detected in larvae, not in pupae or adults. Also, Cry1Ac passed through the midgut into other tissues, such as the hemolymph and fat body, but did not reach the larval integument. Metabolic tests revealed that Cry1Ac degraded most rapidly in the fat body, followed by the hemolymph, peritrophic membrane and its contents. The toxin was metabolized slowly in the midgut, but was degraded in all locations within 48 h. These findings will improve understanding of the functional mechanism of Bt toxins in target insects and the biotransfer and the bioaccumulation of Bt toxins in arthropod food webs in the Bt crop ecosystem.

  2. Field Performance of Bt Eggplants (Solanum melongena L.) in the Philippines: Cry1Ac Expression and Control of the Eggplant Fruit and Shoot Borer (Leucinodes orbonalis Guenée)

    Science.gov (United States)

    Hautea, Desiree M.; Taylo, Lourdes D.; Masanga, Anna Pauleen L.; Sison, Maria Luz J.; Narciso, Josefina O.; Quilloy, Reynaldo B.; Hautea, Randy A.; Shotkoski, Frank A.; Shelton, Anthony M.

    2016-01-01

    Plants expressing Cry proteins from the bacterium, Bacillus thuringiensis (Bt), have become a major tactic for controlling insect pests in maize and cotton globally. However, there are few Bt vegetable crops. Eggplant (Solanum melongena) is a popular vegetable grown throughout Asia that is heavily treated with insecticides to control the eggplant fruit and shoot borer, Leucinodes orbonalis (EFSB). Herein we provide the first publicly available data on field performance in Asia of eggplant engineered to produce the Cry1Ac protein. Replicated field trials with five Bt eggplant open-pollinated (OP) lines from transformation event EE-1 and their non-Bt comparators were conducted over three cropping seasons in the Philippines from 2010–2012. Field trials documented levels of Cry1Ac protein expressed in plants and evaluated their efficacy against the primary target pest, EFSB. Cry1Ac concentrations ranged from 0.75–24.7 ppm dry weight with the highest in the terminal leaves (or shoots) and the lowest in the roots. Cry1Ac levels significantly increased from the vegetative to the reproductive stage. Bt eggplant lines demonstrated excellent control of EFSB. Pairwise analysis of means detected highly significant differences between Bt eggplant lines and their non-Bt comparators for all field efficacy parameters tested. Bt eggplant lines demonstrated high levels of control of EFSB shoot damage (98.6–100%) and fruit damage (98.1–99.7%) and reduced EFSB larval infestation (95.8–99.3%) under the most severe pest pressure during trial 2. Moths that emerged from larvae collected from Bt plants in the field and reared in their Bt eggplant hosts did not produce viable eggs or offspring. These results demonstrate that Bt eggplant lines containing Cry1Ac event EE-1 provide outstanding control of EFSB and can dramatically reduce the need for conventional insecticides. PMID:27322533

  3. 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.

  4. 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…

  5. Reduction of herbivore density as a tool for reduction of herbivore browsing on palatable tree species

    Czech Academy of Sciences Publication Activity Database

    Kamler, Jiří; Homolka, Miloslav; Barančeková, Miroslava; Krojerová-Prokešová, Jarmila

    2010-01-01

    Roč. 129, č. 2 (2010), s. 155-162. ISSN 1612-4669 R&D Projects: GA ČR GP206/03/P134; GA MŠk LC06073 Institutional research plan: CEZ:AV0Z60930519 Keywords : herbivore impact * habitat use * forest regeneration * spruce * beech * rowan Subject RIV: EH - Ecology, Behaviour Impact factor: 1.942, year: 2010

  6. Does herbivorous fish protection really improve coral reef resilience? A case study from new caledonia (South Pacific.

    Directory of Open Access Journals (Sweden)

    Laure Carassou

    Full Text Available Parts of coral reefs from New Caledonia (South Pacific were registered at the UNESCO World Heritage list in 2008. Management strategies aiming at preserving the exceptional ecological value of these reefs in the context of climate change are currently being considered. This study evaluates the appropriateness of an exclusive fishing ban of herbivorous fish as a strategy to enhance coral reef resilience to hurricanes and bleaching in the UNESCO-registered areas of New Caledonia. A two-phase approach was developed: 1 coral, macroalgal, and herbivorous fish communities were examined in four biotopes from 14 reefs submitted to different fishing pressures in New Caledonia, and 2 results from these analyses were challenged in the context of a global synthesis of the relationship between herbivorous fish protection, coral recovery and relative macroalgal development after hurricanes and bleaching. Analyses of New Caledonia data indicated that 1 current fishing pressure only slightly affected herbivorous fish communities in the country, and 2 coral and macroalgal covers remained unrelated, and macroalgal cover was not related to the biomass, density or diversity of macroalgae feeders, whatever the biotope or level of fishing pressure considered. At a global scale, we found no relationship between reef protection status, coral recovery and relative macroalgal development after major climatic events. These results suggest that an exclusive protection of herbivorous fish in New Caledonia is unlikely to improve coral reef resilience to large-scale climatic disturbances, especially in the lightly fished UNESCO-registered areas. More efforts towards the survey and regulation of major chronic stress factors such as mining are rather recommended. In the most heavily fished areas of the country, carnivorous fish and large targeted herbivores may however be monitored as part of a precautionary approach.

  7. Carbon isotope ratios document that the elytra of western corn rootworm (Coleoptera: Chrysomelidae) reflects adult versus larval feeding and later instar larvae prefer Bt corn to alternate hosts.

    Science.gov (United States)

    Hiltpold, Ivan; Adamczyk, John J; Higdon, Matthew L; Clark, Thomas L; Ellersieck, Mark R; Hibbard, Bruce E

    2014-06-01

    In much of the Corn Belt and parts of Europe, the western corn rootworm, Diabrotica virgifera virgifera LeConte, is the most important insect pest of maize. The need for additional basic knowledge of this pest has been highlighted while developing resistance management plans for insecticidal genetically modified crops. This study evaluated the possibility of tracking feeding habits of western corn rootworm larvae using stable carbon isotope signatures. Plants accumulate different ratios of (13)C:(12)C isotopes, usually expressed as δ(13)C, according to whether they use the C3 or C4 photosynthetic pathway. Herbivore biomass is expected to reflect the δ(13)C of the food they eat. For the current experiment, western corn rootworm larvae were grown on different species of plants exhibiting different δ(13)C values. The δ(13)C values were then measured in elytra of emerged beetles. When beetles were unfed, biomass reflected larval feeding. When beetles were fed for 31 d postemergence, δ(13)C values of elytra almost exclusively reflected adult feeding. These results suggest the use of caution in the interpretation of δ(13)C data aiming to document larval diet history when adult feeding history is unknown. The technique was also used to evaluate western corn rootworm larval choice between alternate hosts and maize with and without genetically modified (Bt) traits aimed at their control. Propensity for feeding on alternate hosts versus maize was biased toward feeding on maize regardless whether the maize had Bt or not, suggesting western corn rootworm larvae were not repelled by Bt. These data will be helpful for regulators in interpreting western corn rootworm feeding data on Bt maize. PMID:24874160

  8. Phytohormone mediation of interactions between herbivores and plant pathogens.

    Science.gov (United States)

    Lazebnik, Jenny; Frago, Enric; Dicke, Marcel; van Loon, Joop J A

    2014-07-01

    Induced plant defenses against either pathogens or herbivore attackers are regulated by phytohormones. These phytohormones are increasingly recognized as important mediators of interactions between organisms associated with plants. In this review, we discuss the role of plant defense hormones in sequential tri-partite interactions among plants, pathogenic microbes, and herbivorous insects, based on the most recent literature. We discuss the importance of pathogen trophic strategy in the interaction with herbivores that exhibit different feeding modes. Plant resistance mechanisms also affect plant quality in future interactions with attackers. We discuss exemplary evidence for the hypotheses that (i) biotrophic pathogens can facilitate chewing herbivores, unless plants exhibit effector-triggered immunity, but (ii) facilitate or inhibit phloem feeders. (iii) Necrotrophic pathogens, on the other hand, can inhibit both phloem feeders and chewers. We also propose herbivore feeding mode as predictor of effects on pathogens of different trophic strategies, providing evidence for the hypotheses that (iv) phloem feeders inhibit pathogen attack by increasing SA induction, whereas (v) chewing herbivores tend not to affect necrotrophic pathogens, while they may either inhibit or facilitate biotrophic pathogens. Putting these hypotheses to the test will increase our understanding of phytohormonal regulation of plant defense to sequential attack by plant pathogens and insect herbivores. This will provide valuable insight into plant-mediated ecological interactions among members of the plant-associated community. PMID:25059974

  9. 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

  10. Heliothis virescens and Bt cotton in the United States.

    Science.gov (United States)

    Blanco, Carlos A

    2012-01-01

    The tobacco budworm (TBW), Heliothis virescens (F.), has been responsible for substantial economic losses, environmental pollution and a great challenge to the United States' economy, environment, researchers and cotton and tobacco producers during most of the past two hundred years. If a historical description of this pest problem should be written, it would necessarily be divided into two main events; the pre- and post-Bacillus thuringiensis-expressing (Bt)-cotton era. Before the advent of Bt-cotton, TBW had evolved resistance to most commercial insecticides, making cotton cultivation unfeasible at some point. Subsequently, a variety of clever control measures were developed in an effort to develop more sustainable integrated pest management programs. Without a doubt, Bt-cotton, transformed to produce insecticidal proteins from the soil borne bacterium, B. thuringiensis, is now one of the most important elements of TBW management in US cotton. This discussion could be quite short stating that Bt-cotton has produced an unprecedented level of control for TBW, but beyond this, it is important to note the additional impacts around the argument that Bt-cotton has likely reduced TBW populations over large areas-due to its high efficacy-to the low densities observed today. Cotton area suitable for TBW development has been reduced to ~40% of its pre Bt-cotton years and certainly may be another primary force behind this decline. However, the way we have detected this decline relies mostly on observations made in cotton fields, as well as males trapped in pheromone traps near cotton; these monitoring tools may not fully reflect TBW population levels at the landscape level. My argument supports what has been postulated before that TBW may be in the process of differentiating into "host races" and the cotton host race, once the most abundant in the environment, may be the one greatly affected by this habitat modification now dominated by Bt-cotton, while the other host races

  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. 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

  13. Herbivore-induced plant volatiles to enhance biological control in agriculture.

    Science.gov (United States)

    Peñaflor, M F G V; Bento, J M S

    2013-08-01

    Plants under herbivore attack synthetize defensive organic compounds that directly or indirectly affect herbivore performance and mediate other interactions with the community. The so-called herbivore-induced plant volatiles (HIPVs) consist of odors released by attacked plants that serve as important cues for parasitoids and predators to locate their host/prey. The understanding that has been gained on the ecological role and mechanisms of HIPV emission opens up paths for developing novel strategies integrated with biological control programs with the aim of enhancing the efficacy of natural enemies in suppressing pest populations in crops. Tactics using synthetic HIPVs or chemically/genetically manipulating plant defenses have been suggested in order to recruit natural enemies to plantations or help guiding them to their host more quickly, working as a "synergistic" agent of biological control. This review discusses strategies using HIPVs to enhance biological control that have been proposed in the literature and were categorized here as: (a) exogenous application of elicitors on plants, (b) use of plant varieties that emit attractive HIPVs to natural enemies, (c) release of synthetic HIPVs, and (d) genetic manipulation targeting genes that optimize HIPV emission. We discuss the feasibility, benefits, and downsides of each strategy by considering not only field studies but also comprehensive laboratory assays that present an applied approach for HIPVs or show the potential of employing them in the field. PMID:23949852

  14. Isolation of Gossypol and Analysis of Phytochemicals in Seed Extract of Bt and Non-Bt Varieties of Cotton

    Directory of Open Access Journals (Sweden)

    R.Chandrashekar

    2013-05-01

    Full Text Available The purpose of this study was to isolate the gossypol (Phenolic compound and screening of phytochemical constituents from seed extract. During this study gossypol was extracted from cotton seeds and cotton seed cake using different organic solvents like acetone, ethanol, methanol, pet ether, chloroform and hot water and screened for phytochemical constituents. Analysis revealed the presence of phenols, glycosides, flavonoids, and steroids. Specific tests were conducted for each group of the phytochemicals. Among the extracts tested polar solvents like acetone, ethanol, methanol extracts showed more phytochemicals than others followed by pet ether, hot water, chloroform. The phytochemicals like saponins, flavonoids, tri-terpenoids, and tannins were not found in seed extract, specifically showed phenols with more quantity in polar solvent extract like acetone, ethanol and methanol cardiac glycosides and steroids are observed in both polar and non-polar solvent of seed extracts. Similar kind of compounds are present in Bt and non-Bt but the appearance of test coloration of seed extracts predicted as is slightly darker for Bt variety. This could be due to more amount of the component may be present in Bt cotton seed extract than non-Bt cotton seed extract. The compound Gossypol was detected in extracts by applying Chromatographic technique as well as chemical tests with antimony chloride (SbCl3, and stannic chloride (SnCl3 and leadacetate (Pb(CH3COO2 . Spectrophotometric techniques were also employed for quantitative analysis by measuring absorbance of samples at wavelength of 290nm.

  15. Scoring Strategies for the TOEFL iBT A Complete Guide

    CERN Document Server

    Stirling, Bruce

    2012-01-01

    TOEFL students all ask: How can I get a high TOEFL iBT score? Answer: Learn argument scoring strategies. Why? Because the TOEFL iBT recycles opinion-based and fact-based arguments for testing purposes from start to finish. In other words, the TOEFL iBT is all arguments. That's right, all arguments. If you want a high score, you need essential argument scoring strategies. That is what Scoring Strategies for the TOEFL iBT gives you, and more!. TEST-PROVEN STRATEGIES. Learn essential TOEFL iBT scoring strategies developed in American university classrooms and proven successful on the TOEFL iBT. R

  16. Inducible direct plant defense against insect herbivores: A review

    Institute of Scientific and Technical Information of China (English)

    Ming-Shun Chen

    2008-01-01

    Plants respond to insect herbivory with responses broadly known as direct defenses, indirect defenses, and tolerance. Direct defenses include all plant traits that affect susceptibility of host plants by themselves. Overall categories of direct plant defenses against insect herbivores include limiting food supply, reducing nutrient value, reducing preference, disrupting physical structures, and inhibiting chemical pathways of the attacking insect. Major known defense chemicals include plant secondary metabolites, protein inhibitors of insect digestive enzymes, proteases, lectins, amino acid deaminases and oxidases. Multiple factors with additive or even synergistic impact are usually involved in defense against a specific insect species, and factors of major importance to one insect species may only be of secondary importance or not effective at all against another insect species. Extensive qualitative and quantitative high throughput analyses of temporal and spatial variations in gene expression, protein level and activity, and metabolite concentration will accelerate not only the understanding of the overall mechanisms of direct defense, but also accelerate the identification of specific targets for enhancement of plant resistance for agriculture.

  17. 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

  18. 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.

  19. 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...

  20. Masticatory Motor Patterns in Six Herbivorous Australian Marsupials

    OpenAIRE

    Crompton, Alfred; Skinner, John; Lieberman, Daniel; Owerkovicz, Tomasz

    2007-01-01

    Electomyograms of the adductor muscles of the hairy-nosed wombat (Lasiorhinus latifrons), red kangaroo (Macropus rufus), Tammar wallaby (M. eugenii), koala (Phascolarctos cinereus), potoroo (Potorous tridactylus) and the brush-tailed possum (Trichosurus vulpecula) were analyzed and compared with those of placental herbivores. Marsupials have developed several different and distinct masticatory motor patterns that are all fundamentally different from those of placental herbivores where jaw mov...

  1. 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 ...

  2. 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 (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.

  3. FUM Gene Expression Profile and Fumonisin Production by Fusarium verticillioides Inoculated in Bt and Non-Bt Maize

    OpenAIRE

    Rocha, Liliana O.; Barroso, Vinícius M.; Andrade, Ludmila J.; Pereira, Gustavo H. A.; Ferreira-Castro, Fabiane L.; Duarte, Aildson P.; Michelotto, Marcos D.; Correa, Benedito

    2016-01-01

    This study aimed to determine the levels of fumonisins produced by Fusarium verticillioides and FUM gene expression on Bt (Bacillus thuringiensis) and non-Bt maize, post harvest, during different periods of incubation. Transgenic hybrids 30F35 YG, 2B710 Hx and their isogenic (30F35 and 2B710) were collected from the field and a subset of 30 samples selected for the experiments. Maize samples were sterilized by gamma radiation at a dose of 20 kGy. Samples were then inoculated with F. verticill...

  4. Bt Sweet Corn: What Is It and Why Should We Use It?

    OpenAIRE

    Barlow, Vonny M.; Kuhar, Thomas Patrick, 1969-; Speese, III, John

    2009-01-01

    This publication reviews Transgenic Bt sweet corn hybrids which are a genetically modified organism (GMO) that are the result of combining commercially available sweet corn varieties with genes from a naturally occurring soil bacterium called Bacillus thuringiensis Berliner or Bt.

  5. Insect communities on maize expressing a Bt-toxin

    Czech Academy of Sciences Publication Activity Database

    Habuštová, Oxana; Sehnal, František; Hussein, Hany

    2005-01-01

    Roč. 1, - (2005), s. 9-11. ISSN 1335-258X R&D Projects: GA AV ČR(CZ) KJB6007304 Institutional research plan: CEZ:AV0Z50070508 Keywords : GMO * arthropod communities * Bt maize Subject RIV: EH - Ecology, Behaviour

  6. A biannual study on the environmental impact of Bt maize

    Czech Academy of Sciences Publication Activity Database

    Sehnal, František; Habuštová, Oxana; Spitzer, L.; Hussein, Hany; Růžička, Vlastimil

    2004-01-01

    Roč. 27, č. 3 (2004), s. 147-160. [Ecological Impact of Genetically Modified Organisms. Praha, 26.11.2003-29.11.2003] R&D Projects: GA ČR GA522/02/1507 Institutional research plan: CEZ:AV0Z5007907 Keywords : Bt maize * GM crops * European corn borer Subject RIV: GF - Plant Pathology, Vermin, Weed, Plant Protection

  7. Susceptibility of Ostrinia furnacalis to Bacillus thuringiensis and Bt Corn Under Long-Term Laboratory Selection

    Institute of Scientific and Technical Information of China (English)

    WEN Li-ping; HE Kang-lai; WANG Zhen-ying; ZHOU Da-rong; BAI Shu-xiong

    2005-01-01

    The susceptibility of the Asian corn borer, Ostrinia furnacalis to Bacillus thuringiensis (Bt) formulation and Bt corn was evaluated using insect bioassays for 6 years. Four strains of O. furnacalis were developed by laboratory selection from the laboratory strain reared on a non-agar semi-artificial diet. The RR-1 strain was exposed to a commercial formulation of B. thuringiensis subsp. kurstaki (Btk) incorporated into the artificial diet, the RR-2 strain was exposed to Bt corn (MON810)tissue incorporated into the diet, and the SS-1 and SS-2 strains were reared on the standard diet with or without non-Bt corn tissues material. Decreasing susceptibility of O. furnacalis to Bt and to Bt corn were found in each selected strain although the ED50 and larval weight fluctuated from generation to generation. The resistance of Bt-exposed strain (RR-1)to Btk increased 48-fold by generation 39; the Bt corn-exposed strain (RR-2) increased its resistance 37-fold to Btk by generation 24. No larvae of SS-1 survived when they were exposed to the leaves of Bt corn, Bt1 1 and MON810. However,2-54% of the RR-1 (generation 46) and RR-2 (generation 20) larvae survived a 3 day-exposure to the leaves of Bt1 1 and MON810. The survival of both selected strains on Bt corn silk increased by 10-69%, and the larval weights after many generations selection were increased by 15-22% compared with the unselected susceptible strain. The young larvae were much more susceptible to Bt than older larvae. The highest mortality occurred when the larvae were exposed to Bt at the neonate stage. All of the results suggested that ACB could not only develop resistance to Bt preparation but also to Bt corn. Bt had significant effects on the growth and development of Asian corn borer than on the larval mortality. In order to maintain the long-term effectiveness of Bt pesticide and Bt corn, the resistance management should pay much attention to the larvae that may have opportunities to grow and developed on non-Bt

  8. Genetic mapping of Bt-toxin binding proteins in a Cry1A-toxin resistant strain of diamondback moth Plutella xylostella.

    Science.gov (United States)

    Baxter, Simon W; Zhao, Jian-Zhou; Shelton, Anthony M; Vogel, Heiko; Heckel, David G

    2008-02-01

    A major mechanism of resistance to Bacillus thuringiensis (Bt) toxins in Lepidoptera is a reduction of toxin binding to sites in the midgut membrane. Genetic studies of three different species have shown that mutations in a candidate Bt receptor, a 12-cadherin-domain protein, confer Cry1A toxin resistance. Despite a similar resistance profile in a fourth lepidopteran species, Plutella xylostella, we have previously shown that the cadherin orthologue maps to a different linkage group (LG8) than Cry1Ac resistance (LG22). Here we tested the hypothesis that mutations in other genes encoding candidate Bt-binding targets could be responsible for Bt resistance, by mapping eight aminopeptidases, an alkaline phosphatase (ALP), an intestinal mucin, and a P252 glycoprotein with respect to the 29 AFLP marked linkage groups in a P. xylostella cross segregating for Cry1Ac resistance. A homologue of the Caenorhabditis elegans Bt resistance gene bre-2 was also mapped. None of the genes analysed were on the same chromosome containing the Cry1Ac resistance locus, eliminating them as candidate resistance genes in the parental resistant strain SC1. Although this finding excludes cis-acting mutations in these genes as causing resistance in this strain, one or more of the expressed proteins may still bind Cry1Ac toxin, and post-translational modifications could affect this binding and thereby exert a trans-acting effect on resistance. PMID:18207074

  9. Genetic markers for western corn rootworm resistance to Bt toxin.

    Science.gov (United States)

    Flagel, Lex E; Swarup, Shilpa; Chen, Mao; Bauer, Christopher; Wanjugi, Humphrey; Carroll, Matthew; Hill, Patrick; Tuscan, Meghan; Bansal, Raman; Flannagan, Ronald; Clark, Thomas L; Michel, Andrew P; Head, Graham P; Goldman, Barry S

    2015-03-01

    Western corn rootworm (WCR) is a major maize (Zea mays L.) pest leading to annual economic losses of more than 1 billion dollars in the United States. Transgenic maize expressing insecticidal toxins derived from the bacterium Bacillus thuringiensis (Bt) are widely used for the management of WCR. However, cultivation of Bt-expressing maize places intense selection pressure on pest populations to evolve resistance. Instances of resistance to Bt toxins have been reported in WCR. Developing genetic markers for resistance will help in characterizing the extent of existing issues, predicting where future field failures may occur, improving insect resistance management strategies, and in designing and sustainably implementing forthcoming WCR control products. Here, we discover and validate genetic markers in WCR that are associated with resistance to the Cry3Bb1 Bt toxin. A field-derived WCR population known to be resistant to the Cry3Bb1 Bt toxin was used to generate a genetic map and to identify a genomic region associated with Cry3Bb1 resistance. Our results indicate that resistance is inherited in a nearly recessive manner and associated with a single autosomal linkage group. Markers tightly linked with resistance were validated using WCR populations collected from Cry3Bb1 maize fields showing significant WCR damage from across the US Corn Belt. Two markers were found to be correlated with both diet (R2 = 0.14) and plant (R2 = 0.23) bioassays for resistance. These results will assist in assessing resistance risk for different WCR populations, and can be used to improve insect resistance management strategies. PMID:25566794

  10. ADVERSE SELECTION, MORAL HAZARD, AND GROWER COMPLIANCE WITH BT CORN REFUGE

    OpenAIRE

    Mitchell, Paul D.; Zhu, En (John); Terrance M. Hurley

    2004-01-01

    This paper develops a principal-agent model of farmer compliance with Bt corn refuge requirements intended to manage the evolution of resistance to the Bt toxin by insect pests. The model endogenizes the price of the technology, the audit rate, and the fine imposed on non-complying farmers when farmer willingness to pay for Bt corn and compliance effort is private information.

  11. Effects of Transgenic Bt Rice on Nontarget Rhopalosiphum maidis (Homoptera: Aphididae).

    Science.gov (United States)

    Ren, Shao-Peng; Yang, Fan; Gao, Ming-Qing; Pu, De-Qiang; Shi, Min; Ye, Gong-Yin; Shen, Zhi-Cheng; Chen, Xue-Xin

    2016-08-01

    The effects of three transgenic Bacillus thuringiensis (Bt) rice lines, KMD1, KMD2, and G8-7, on biological parameters and population dynamics of nontarget insect, Rhopalosiphum maidis (Fitch) (Homoptera: Aphididae), were investigated in the laboratory and field. No significant differences were found between Bt and non-Bt rice lines for aphid survival. The developmental time of R. maidis that fed on KMD1 and KMD2 did not differ significantly from those of the individuals feeding on the parental variety Xiushui11, but significantly prolonged developmental time was observed on G8-7 as compared with its parental variety Xiushui110. Aphid fecundity was significantly higher on Bt than on parental rice. A 2-yr field survey indicated that Bt rice did not significantly affect the population dynamics of R. maidis in comparison with non-Bt rice. Additionally, guttation droplets of Bt rice and aphids feeding on Bt rice were analyzed for presence of Cry1Ab using ELISA. No Cry1Ab protein was found in aphid adults feeding on Bt rice lines both in the laboratory and field. By using the guttation droplets from the top of rice seedlings, we designed a novel method to collect phloem sap, and found that relatively low concentrations were detected in the guttation droplets from Bt rice lines. In conclusion, although the Bt rice lines tested in this study stimulate the fecundity of R. maidis, the aphid population density did not increase in Bt rice fields. PMID:27389683

  12. SNS ønsker kommentarer om oplysninger fra Syngenta Seeds vedr forurening med Bt10 i Bt11-majsen ændrer konklusionerne i risikovurderingen. Zea mays (Bt11) . Supplerende informationer om Bt11 - evt. konsekvenser for tidligere vurderinger. Modtaget 04-05-2005, deadline 06-06-2005, svar 24-05-2005

    DEFF Research Database (Denmark)

    Kjellsson, Gøsta

    2012-01-01

    "Vedr. oplysningerne om iblanding af Bt-10 majsen i Bt-11 viser det tilsendte materiale, at Syngenta har undersøgt og fået bekræftet at undersøgelserne til grundlag for risikovurderingen blev foretaget på Bt-11 majs. DMU ser derfor ingen grund til at ændre konklusionerne i den tidligere risikovur...

  13. Test Takers' Attitudes about the TOEFL iBT[TM]. TOEFL iBT Research Report. RR-10-2

    Science.gov (United States)

    Stricker, Lawrence J.; Attali, Yigal

    2010-01-01

    The principal aims of this study, a conceptual replication of an earlier investigation of the TOEFL[R] computer-based test, or TOEFL CBT, in Buenos Aires, Cairo, and Frankfurt, were to assess test takers' reported acceptance of the TOEFL Internet-based test, or TOEFL iBT[TM], and its associations with possible determinants of this acceptance and…

  14. 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

  15. FUM Gene Expression Profile and Fumonisin Production by Fusarium verticillioides Inoculated in Bt and Non-Bt Maize.

    Science.gov (United States)

    Rocha, Liliana O; Barroso, Vinícius M; Andrade, Ludmila J; Pereira, Gustavo H A; Ferreira-Castro, Fabiane L; Duarte, Aildson P; Michelotto, Marcos D; Correa, Benedito

    2015-01-01

    This study aimed to determine the levels of fumonisins produced by Fusarium verticillioides and FUM gene expression on Bt (Bacillus thuringiensis) and non-Bt maize, post harvest, during different periods of incubation. Transgenic hybrids 30F35 YG, 2B710 Hx and their isogenic (30F35 and 2B710) were collected from the field and a subset of 30 samples selected for the experiments. Maize samples were sterilized by gamma radiation at a dose of 20 kGy. Samples were then inoculated with F. verticillioides and analyzed under controlled conditions of temperature and relative humidity for fumonisin B1 and B2 (FB1 and FB2) production and FUM1, FUM3, FUM6, FUM7, FUM8, FUM13, FUM14, FUM15, and FUM19 expression. 2B710 Hx and 30F35 YG kernel samples were virtually intact when compared to the non-Bt hybrids that came from the field. Statistical analysis showed that FB1 production was significantly lower in 30F35 YG and 2B710 Hx than in the 30F35 and 2B710 hybrids (P 0.05). The kernel injuries observed in the non-Bt samples have possibly facilitated F. verticillioides penetration and promoted FB1 production under controlled conditions. FUM genes were expressed by F. verticillioides in all of the samples. However, there was indication of lower expression of a few FUM genes in the Bt hybrids; and a weak association between FB1 production and the relative expression of some of the FUM genes were observed in the 30F35 YG hybrid. PMID:26779158

  16. FUM gene expression profile and fumonisin production by Fusarium verticillioides inoculated in Bt and non-Bt maize

    Directory of Open Access Journals (Sweden)

    Liliana Oliveira Rocha

    2016-01-01

    Full Text Available This study aimed to determine the levels of fumonisins produced by F. verticillioides and FUM gene expression on Bt (Bacillus thuringiensis and non-Bt maize, post harvest, during different periods of incubation. Transgenic hybrids 30F35 YG, 2B710 Hx and their isogenic (30F35 and 2B710 were collected from the field and a subset of 30 samples selected for the experiments. Maize samples were sterilized by gamma radiation at a dose of 20 kGy. Samples were then inoculated with Fusarium verticillioides and analysed under controlled conditions of temperature and relative humidity for fumonisin B1 and B2 (FB¬1 and FB2 production and FUM1, FUM3, FUM6, FUM7, FUM8, FUM13, FUM14, FUM15 and FUM19 expression. 2B710 Hx and 30F35 YG kernel samples were virtually intact when compared to the non-Bt hybrids that came from the field. Statistical analysis showed that FB¬1 production was significantly lower in 30F35 YG and 2B710 Hx than in the 30F35 and 2B710 hybrids (P 0.05. The kernel injuries observed in the non-Bt samples have possibly facilitated F. verticillioides penetration and promoted FB1 production under controlled conditions. FUM genes were expressed by F. verticillioides in all of the samples. However, there was indication of lower expression of a few FUM genes in the Bt hybrids; and a weak association between FB1 production and the relative expression of some of the FUM genes were observed in the 30F35 YG hybrid.

  17. FUM Gene Expression Profile and Fumonisin Production by Fusarium verticillioides Inoculated in Bt and Non-Bt Maize

    Science.gov (United States)

    Rocha, Liliana O.; Barroso, Vinícius M.; Andrade, Ludmila J.; Pereira, Gustavo H. A.; Ferreira-Castro, Fabiane L.; Duarte, Aildson P.; Michelotto, Marcos D.; Correa, Benedito

    2016-01-01

    This study aimed to determine the levels of fumonisins produced by Fusarium verticillioides and FUM gene expression on Bt (Bacillus thuringiensis) and non-Bt maize, post harvest, during different periods of incubation. Transgenic hybrids 30F35 YG, 2B710 Hx and their isogenic (30F35 and 2B710) were collected from the field and a subset of 30 samples selected for the experiments. Maize samples were sterilized by gamma radiation at a dose of 20 kGy. Samples were then inoculated with F. verticillioides and analyzed under controlled conditions of temperature and relative humidity for fumonisin B1 and B2 (FB1 and FB2) production and FUM1, FUM3, FUM6, FUM7, FUM8, FUM13, FUM14, FUM15, and FUM19 expression. 2B710 Hx and 30F35 YG kernel samples were virtually intact when compared to the non-Bt hybrids that came from the field. Statistical analysis showed that FB1 production was significantly lower in 30F35 YG and 2B710 Hx than in the 30F35 and 2B710 hybrids (P 0.05). The kernel injuries observed in the non-Bt samples have possibly facilitated F. verticillioides penetration and promoted FB1 production under controlled conditions. FUM genes were expressed by F. verticillioides in all of the samples. However, there was indication of lower expression of a few FUM genes in the Bt hybrids; and a weak association between FB1 production and the relative expression of some of the FUM genes were observed in the 30F35 YG hybrid. PMID:26779158

  18. Eco-physiological response of two marine bivalves to acute exposition to commercial Bt-based pesticide.

    Science.gov (United States)

    Manachini, B; Arizza, V; Rinaldi, A; Montalto, V; Sarà, G

    2013-02-01

    Microbial products based on the entomopathogenic bacterium Bacillus thuringiensis (Bt) are among the most common biopesticides used worldwide to suppress insect pests in forests, horticulture and agricultural crops. Some of the effects of commercial Bt have been recorded for terrestrial and freshwater non-target organisms but little research is available on marine fauna. Nevertheless, due to the contiguity of agro-ecosystems and coastal habitats, marine fauna may be highly influenced by this control method. We studied the effect of a commercial Bt product on the physiological and ecological responses and the energy budget of two of the most frequent marine intertidal bivalves in the Mediterranean, the native Mytilaster minimus and the invasive Brachidontes pharaonis. To test the effects experimentally, we simulated the worst scenarios possible using the average dose applied to fields and a hypothetical accumulation dose. The results showed the feeding rates of both species were affected detrimentally by the different experimental conditions; higher concentrations led to higher respiration rates, however neither species showed any significant difference in excretion rates. The biopesticide had a significant effect on the energy budget, the values decreasing with doses. In addition, it led to high mortality for the worst treatments and, in both species, induced significantly higher cardiac activity than in the controls. These results indicate a measurable effect of Bt commercial products on marine organisms, and great attention should be paid to biopesticides composed by entomopathogenic bacteria and addictive compounds. In addition, the results highlight the urgent need to study not only the effects of anthropogenic pressures on target organisms but also to extend our view to other ecosystems not expected to be influenced. Gaining data at the organismal level should help increase the sustainability of pest control and reduce the consequences of side-effects. PMID

  19. Calculation and Analysis of B/T (Burning and/or Transmutation Rate of Minor Actinides and Plutonium Performed by Fast B/T Reactor

    Directory of Open Access Journals (Sweden)

    Marsodi

    2006-01-01

    Full Text Available Calculation and analysis of B/T (Burning and/or Transmutation rate of MA (minor actinides and Pu (Plutonium has been performed in fast B/T reactor. The study was based on the assumption that the spectrum shift of neutron flux to higher side of neutron energy had a potential significance for designing the fast B/T reactor and a remarkable effect for increasing the B/T rate of MA and/or Pu. The spectrum shifts of neutron have been performed by change MOX to metallic fuel. Blending fraction of MA and or Pu in B/T fuel and the volume ratio of fuel to coolant in the reactor core were also considered. Here, the performance of fast B/T reactor was evaluated theoretically based on the calculation results of the neutronics and burn-up analysis. In this study, the B/T rate of MA and/or Pu increased by increasing the blending fraction of MA and or Pu and by changing the F/C ratio. According to the results, the total B/T rate, i.e. [B/T rate]MA + [B/T rate]Pu, could be kept nearly constant under the critical condition, if the sum of the MA and Pu inventory in the core is nearly constant. The effect of loading structure was examined for inner or outer loading of concentric geometry and for homogeneous loading. Homogeneous loading of B/T fuel was the good structure for obtaining the higher B/T rate, rather than inner or outer loading

  20. Changes in bacillus thuringiensis tolerance levels due to hybridization of Bt-tolerant and susceptible silkworm populations

    International Nuclear Information System (INIS)

    Males and females of a Bt-tolerant mulberry silkworm (Bombyx mori L.) population were crossed with females and males of a Bt-susceptible population, to produce Bt-tolerant silkworm hybrids, and to determine the expression of the Bt-tolerance pattern in the F 1 hybrids. It was observed that when a Bt-tolerant (42% larval mortality) female (BtT ) silkworm was crossed with a Bt-susceptible (85% larval mortality) male (BtS ), the resultant F 1 offspring showed lower levels of Bt-tolerance (87% larval mortality). On the other hand, when a Bt-tolerant male (BtT ) was crossed with a Bt-susceptible female (BtS ), the F 1 hybrid showed higher levels of Bt-tolerance (35% larval mortality) characteristic. The probit statistics showed that both hybrids expressed Bt-tolerance or susceptible levels similar to their male parents. These different patterns of Bt-tolerance in F 1 hybrids might be due to the transferring of a Bt-tolerant gene, from the parents to offspring, through the homozygotic male (ZZ) silkworm. (author)

  1. Development and Adoption of Bt Cotton in India : Economic, Environmental and Health Issues

    OpenAIRE

    -, Dr S Saravanan; -, Dr V Mohanasundaram

    2016-01-01

    Bt Cotton, is genetically engineered with Bt (Bacillus thuringiensis), a bio-toxin which comes from soil bacterium. Bt which was isolated from soil in 1911, has been available to farmers as an organic pesticide since 1930..The engineered Bt gene produces a protein that cuts into the guts of specific insects, rendering the cotton resistant to these insects. Biotechnology for control of bollworms is made available in the seed itself. Farmers have to just sow the Bt cotton seeds as they do with...

  2. Herbivore-induced resource sequestration in plants: why bother?

    Science.gov (United States)

    Orians, Colin M; Thorn, Alexandra; Gómez, Sara

    2011-09-01

    Herbivores can cause numerous changes in primary plant metabolism. Recent studies using radioisotopes, for example, have found that insect herbivores and related cues can induce faster export from leaves and roots and greater partitioning into tissues inaccessible to foraging herbivores. This process, termed induced resource sequestration, is being proposed as an important response of plants to cope with herbivory. Here, we review the evidence for resource sequestration and suggest that associated allocation and ecological costs may limit the benefit of this response because resources allocated to storage are not immediately available to other plant functions or may be consumed by other enemies. We then present a conceptual model that describes the conditions under which benefits might outweigh costs of induced resource sequestration. Benefits and costs are discussed in the context of differences in plant life-history traits and biotic and abiotic conditions, and new testable hypotheses are presented to guide future research. We predict that intrinsic factors related to life history, ontogeny and phenology will alter patterns of induced sequestration. We also predict that induced sequestration will depend on certain external factors: abiotic conditions, types of herbivores, and trophic interactions. We hope the concepts presented here will stimulate more focused research on the ecological and evolutionary costs and benefits of herbivore-induced resource sequestration. PMID:21431939

  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 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......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...... 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. 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

  5. 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,...

  6. 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

  7. Arthropod abundance and diversity in transgenic Bt soybean.

    Science.gov (United States)

    Yu, Huilin; Li, Yunhe; Li, Xiangju; Wu, Kongming

    2014-08-01

    Before the commercialization of any insect-resistant genetically modified crop, it must be subjected to a rigorous premarket risk assessment. Here, possible effects of growing of transgenic Cry1Ac soybean on arthropod communities under field conditions were assessed for 2 yr and quantified in terms of arthropod community indices including the Shannon-Weaver diversity index, richness index, and dominance index. Our results showed no significant differences of diversity, richness, or dominant indices for Bt soybean compared with the recipient cultivar, conventional soybean, or sprayed conventional soybean. Conventional soybean treatment with insecticide had an adverse effect on the arthropod community after spraying, but arthropod community diversity recovered quickly. Bt soybean had no negative effect on the dominant distribution of subcommunities, including sucking pests, other pests, predators, parasitoids, and others except for lepidopteran pests. The dominance distribution of lepidopteran pests decreased significantly in Bt soybean because of the significant decrease in the numbers of Spodoptera litura (F.) and Ascotis selenaria Schiffermüller et Denis compared with the recipient cultivar. Our results showed that there were no negative effects of Cry1Ac soybean on the arthropod community in soybean field plots in the short term. PMID:24915416

  8. The impact of secondary pests on Bacillus thuringiensis (Bt) crops.

    Science.gov (United States)

    Catarino, Rui; Ceddia, Graziano; Areal, Francisco J; Park, Julian

    2015-06-01

    The intensification of agriculture and the development of synthetic insecticides enabled worldwide grain production to more than double in the last third of the 20th century. However, the heavy dependence and, in some cases, overuse of insecticides has been responsible for negative environmental and ecological impacts across the globe, such as a reduction in biodiversity, insect resistance to insecticides, negative effects on nontarget species (e.g. natural enemies) and the development of secondary pests. The use of recombinant DNA technology to develop genetically engineered insect-resistant crops could mitigate many of the negative side effects of insecticides. One such genetic alteration enables crops to express toxic crystalline (Cry) proteins from the soil bacteria Bacillus thuringiensis (Bt). Despite the widespread adoption of Bt crops, there are still a range of unanswered questions concerning longer term agro-ecosystem interactions. For instance, insect species that are not susceptible to the expressed toxin can develop into secondary pests and cause significant damage to the crop. Here, we review the main causes surrounding secondary pest dynamics in Bt crops and the impact of such outbreaks. Regardless of the causes, if nonsusceptible secondary pest populations exceed economic thresholds, insecticide spraying could become the immediate solution at farmers' disposal, and the sustainable use of this genetic modification technology may be in jeopardy. Based on the literature, recommendations for future research are outlined that will help to improve the knowledge of the possible long-term ecological trophic interactions of employing this technology. PMID:25832330

  9. Influences of Soil Fertility on Spatial Patterns of Aphis Gossypii Glover (Homoptera: Aphididae Occurred in Bt-cotton Plants

    Directory of Open Access Journals (Sweden)

    Zhi-Qiang Tan

    2012-12-01

    Full Text Available With the widespread planting of bacterium Bacillus thuringiensis (Bt-cotton, non-target piercing-sucking insects such as Aphis gossypii Glover (Homoptera: Aphididae have become the main hazard of cotton. Fertilization influences the distribution and population dynamics of aphid seriously. In this study, the effects of Nitrogen (N and Phosphorus (P on aphid population density were investigated on Bt-cotton; the combinational impacts of nitrogen and potassium (K fertilizers on the distribution of aphid were examined as to guide rational fertilization to reduce pests and environmental pollution. Aphid density in cotton plants fertilized with 72 kg/ha N (84.2±22.7 aphids/plant was significantly higher than fertilized with 0 and 108 kg/ha N (36.7±4.0 and 47.8±18.7 aphids/plant. Compared to cotton plants treated with 23 and 69 kg/ha P, aphid density was higher (61.67±21.08 aphids/plant in cotton plants treated with 46 kg/ha P. Comparison of spatial distribution of aphid population showed that aphid preferred to suck the sap of bottom fruit branches in cotton plants treated by single K fertilizer and combinational fertilizers of N and K. Thus, these results suggested that proper application of fertilizers should be beneficial to controlling phytophagous insects in Bt-cotton production.

  10. 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

  11. 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...

  12. A comprehensive assessment of the effects of Bt cotton on Coleomegilla maculata demonstrates no detrimental effects by Cry1Ac and Cry2Ab.

    Directory of Open Access Journals (Sweden)

    Yunhe Li

    Full Text Available The ladybird beetle, Coleomegilla maculata (DeGeer, is a common and abundant predator in many cropping systems. Its larvae and adults are predaceous, feeding on aphids, thrips, lepidopteran larvae and plant tissues, such as pollen. Therefore, this species is exposed to insecticidal proteins expressed in insect-resistant, genetically engineered cotton expressing Cry proteins derived from Bacillus thuringiensis (Bt. A tritrophic bioassay was conduced to evaluate the potential impact of Cry2Ab- and Cry1Ac-expressing cotton on fitness parameters of C. maculata using Bt-susceptible and -resistant larvae of Trichoplusia ni as prey. Coleomegilla maculata survival, development time, adult weight and fecundity were not different when they were fed with resistant T. ni larvae reared on either Bt or control cotton. To ensure that C. maculata were not sensitive to the tested Cry toxins independent from the plant background and to add certainty to the hazard assessment, C. maculata larvae were fed artificial diet incorporated with Cry2Ab, Cry1Ac or both at >10 times higher concentrations than in cotton tissue. Artificial diet containing E-64 was included as a positive control. No differences were detected in any life-table parameters between Cry protein-containing diet treatments and the control diet. In contrast, larvae of C. maculata fed the E-64 could not develop to the pupal stage and the 7-d larval weight was significantly negatively affected. In both feeding assays, the stability and bioactivity of Cry proteins in the food sources were confirmed by ELISA and sensitive-insect bioassays. Our results show that C. maculata is not affected by Bt cotton and is not sensitive to Cry2Ab and Cry1Ac at concentrations exceeding the levels in Bt cotton, thus demonstrating that Bt cotton will pose a negligible risk to C. maculata. More importantly, this study demonstrates a comprehensive system for assessing the risk of genetically modified plants on non-target

  13. Multiplex, construct-specific, and real-time PCR-based analytical methods for Bt rice with cry1Ac gene.

    Science.gov (United States)

    Randhawa, Gurinder Jit; Singh, Monika

    2012-01-01

    Qualitative and quantitative analytical methods based on PCR for Bacillus thuringiensis (Bt) rice hybrid, namely, MRP 5401 Bt expressing a modified version of the Bt cry1Ac gene, are reported here. Multiplex PCR assays were developed to target the cry1Ac transgene, Cauliflower mosaic virus (CaMV) 35S promoter, Agrobacterium tumefaciens nopaline synthase (nos) terminator, the neomycin phosphotransferase II (nptLL) marker gene, and an endogenous a-tubulin (TubA) gene in Bt rice. The 3.178 kb region of inserted gene construct comprising the region of the CaMV 35S promoter and cry1Ac gene was amplified, and the construct integrity was confirmed by the nested PCR. The LOD for cry1Ac gene-specific simplex PCR was 0.01%, as established using Bt rice DNA dilutions with 100, 10, 1.0, 0.1, 0.05, 0.01, and 0.001% genetically modified trait. A real-time PCR assay was also developed to quantify the cry1Ac gene. The method performance of the reported real-time PCR assay was in line with the acceptance criteria of Codex Alimentarius Commission ALINORM 10/33/23, with LOD and LOQ values of 0.05%. The reliable PCR assays prior to commercial release of Bt rice would facilitate efficient regulatory compliance for identification of genetic trait, labeling requirements, and effective risk assessment and management. They could also address consumers' concerns and legal disputes that may arise. PMID:22468358

  14. 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...

  15. 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 ...

  16. 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

  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. 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

  19. 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.

  20. 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

  1. 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 ...

  2. 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

  3. 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.

  4. 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

  5. Modified accumulation of selected heavy metals in Bt transgenic rice

    Institute of Scientific and Technical Information of China (English)

    WANG Haiyan; HUANG Jianzhong; YE Qingfu; WU Dianxing; CHEN Ziyuan

    2009-01-01

    Safety assessment of genetically modified crops generally does not take into account the potential hazard of altered patterns of heavy metal accumulation in plants.A pot experiment was conducted under greenhouse conditions to evaluate the impact of heavy metal amendments on the accumulation of Cd,Cu,Pb and Zn in a Bt transgenic rice Ke-Ming-Dao (KMD) and its wild-type Xiushui 11 (Xs11).In control soils,significant difference was only found in contents of Cu (p < 0.01) and Pb (p < 0.05) in straw between KMD and Xs11.At three levels of Cd amendments (5,10,and 20 mg/kg),the Cd contents in grain and straw of KMD were significantly higher than those of Xs11,and all grain Cd contents were significantly higher than the international criteria (0.2-0.4 mg/kg) as specified by the Codex Alimentarius Commission (CAC).These results implied that it may be unsafe for growing Bt transgenic rice in heavily Cd-polluted areas.No significant difference in Zn was found between the two varieties with the exception of roots at Zn amendment level of 600 mg/kg,while Pb contents in KMD were much higher in the straw at the lead amendment level of 1000 mg/kg and in the root at 250 mg Pb/kg.Data on the heavy metal accumulation patterns for the genetically modified rice may be used for the selection of growing areas as well as for plant residue management for Bt rice.

  6. Estimating the Benefits of Bt Corn and Cost of Insect Resistance Management Ex Ante

    OpenAIRE

    Terrance M. Hurley; Langrock, Ines; Ostlie, Kenneth

    2006-01-01

    This paper estimates farmer benefits for corn rootworm (CRW) active Bt corn and costs of complying with Environmental Protection Agency insect resistance management requirements. The estimates are obtained from farmer survey data that were collected in Minnesota in 2002, just prior to the commercial releases of CRW Bt corn. Benefit estimates range from $14 to $33.4 million, while compliance cost estimated range from $3.5 to $8.7 million depending on whether or not CRW Bt corn also controlled ...

  7. Capturing the interaction types of two Bt toxins Cry1Ac and Cry2Ab on suppressing the cotton bollworm by using multi-exponential equations.

    Science.gov (United States)

    Shi, Pei-Jian; Wei, Ji-Zhen; Sandhu, Hardev S; Liang, Ge-Mei

    2016-08-01

    Transgenic crops are increasingly promoted for their practical effects on suppressing certain insect pests, but all transgenic crops are not equally successful. The insect pests can easily develop resistance against single Bacillus thuringiensis (Bt) toxin transgenic crops. Therefore, transgenic crops including two or more mixed Bt-toxins can solve this problem by delaying the resistance development and killing the majority of targeted pests before the evolution of resistance. It is important to test the controlling effects of transgenic crops including multiple mixed toxins on a particular insect pest. Previous research has checked the cross-resistance and interactions between Bt toxins Cry1Ac and Cry2Ab against one susceptible and four resistant strains of cotton bollworm. The results showed that independence was the main interaction type between two toxins for the susceptible strain, whereas synergism was the main interaction type for any one resistant strain. However, the optimal combinations of two toxins were not obtained. In the present study, we developed two multi-exponential equations (namely bi- and tri-exponential equations) to describe the combination effects of two Bt toxins. Importantly, the equations can provide predictions of combination effects of different continuous concentrations of two toxins. We compared these two multi-exponential equations with the generalized linear model (GLM) in describing the combination effects, and found that the bi- and tri-exponential equations are better than GLM. Moreover, the bi-exponential equation can also provide the optimal dose combinations for two toxins. PMID:26314801

  8. Insect herbivores change the outcome of plant competition through both inter- and intraspecific processes.

    Science.gov (United States)

    Kim, Tania N; Underwood, Nora; Inouye, Brian D

    2013-08-01

    Insect herbivores can affect plant abundance and community composition, and theory suggests that herbivores influence plant communities by altering interspecific interactions among plants. Because the outcome of interspecific interactions is influenced by the per capita competitive ability of plants, density dependence, and intrinsic rates of increase, measuring herbivore effects on all these processes is necessary to understand the mechanisms by which herbivores influence plant communities. We fit alternative competition models to data from a response surface experiment conducted over four years to examine how herbivores affected the outcome of competition between two perennial plants, Solidago altissima and Solanum carolinense. Within a growing season, herbivores reduced S. carolinense plant size but did not affect the size of S. altissima, which exhibited compensatory growth. Across seasons, herbivores did not affect S. carolinense density or biomass but reduced both the density and population growth of S. altissima. The best-fit models indicated that the effects of herbivores varied with year. In some years, herbivores increased the per capita competitive effect of S. altissima on S. carolinense; in other years, herbivores influenced the intrinsic rate of increase of S. altissima. We examined possible herbivore effects on the longer-term outcome of competition (over the time scale of a typical old-field habitat), using simulations based on the best-fit models. In the absence of herbivores, plant coexistence was observed. In the presence of herbivores, S. carolinense was excluded by S. altissima in 72.3% of the simulations. We demonstrate that herbivores can influence the outcome of competition through changes in both per capita competitive effects and intrinsic rates of increase. We discuss the implications of these results for ecological succession and biocontrol. PMID:24015519

  9. THE EFFECT OF ARTIFICIAL INOCULATION WITH SELECTED FUSARIUM STRAINS ON NUTRITIONAL QUALITY AN ENSILING PROCESS OF BT MAIZE

    Directory of Open Access Journals (Sweden)

    Ludmila KŘÍŽOVÁ

    2011-01-01

    Full Text Available The objective of the study was to compare the nutritive value and mycotoxin content of maize forage and silage of near isogenic control MONUMENTAL (C and Bt maize (MONSANTO, MON 810 that was either untreated (Bt or artificially inoculated with Fusarium strains (I-Bt. The inoculation was made in the growing crop in milk stage of maturity. Plants were harvested at the soft dough stage of maturity and ensiled in microsilage tubes. The content of forage dry matter (DM was 307.6 g/kg in C, 306.9 g/kg in Bt and 298.0 g/kg in I-Bt. All forages were positive for deoxynivalenol, aflatoxin, fumonisins and zearalenone (P>0.05. Content of DM was the lowest in I-Bt silage (285.5 g/kg and differed significantly from C (296.7 g/kg or Bt (303.7 g/kg, P<0.05. Content of crude protein (CP was the lowest in I-Bt silage (79.0 g/kg and differed significantly from C or Bt (85.7 or 81.9 g/kg, respectively, P<0.05. Silages Bt and I-Bt had lower pH (3.93 and 3.96, respectively than silage C (4.02, P<0.05. Silage I-Bt tended to have a higher degree of proteolysis 9.18 % measured as N-NH3 (% of total N than silages C or Bt (8.64 or 8.9 %, respectively, P>0.05. Lactic acid was predominant product of fermentation in all silages, however silage I-Bt tended to have lower content of lactic acid (20.96 g/kg than C or Bt (24.76 or 23.82 g/kg, P>0.05. I-Bt silage contained lower levels of eoxynivalenol (602 ppb than C or Bt silage (748 and 690 ppb, respectively, P<0.05. Content of fumonisins and zearalenone in C did not differ from I-Bt (P<0.05 but both were lower than in Bt (P<0.05. In conclusion, nutritional value a fermentation parameters of Bt silage were similar to C except of CP content and pH that was lower in Bt (P<0.05. I-Bt silage had lower content of DM, CP and fat than Bt silage (P<0.05. Controversially, concentrations of mycotoxins in I-Bt silage were lower than in Bt.

  10. 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.

  11. 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

  12. Species- and site-specific impacts of an invasive herbivore on tree survival in mixed forests.

    Science.gov (United States)

    Holland, E Penelope; Gormley, Andrew M; Pech, Roger P

    2016-04-01

    Invasive herbivores are often managed to limit their negative impact on plant populations, but herbivore density - plant damage relationships are notoriously spatially and temporally variable. Site and species characteristics (both plant and herbivore) must be considered when assessing the potential for herbivore damage, making it difficult to set thresholds for efficient management. Using the invasive brushtail possum Trichosurus vulpecula in New Zealand as a case study, we parameterized a generic model to predict annual probability of browse-induced mortality of five tree species at 12 sites. We compared predicted and observed tree mortality for each species + site combination to establish herbivore abundance - tree mortality thresholds for each site on a single and combined tree species basis. Model results indicated it is likely that possum browse was the primary cause of all tree mortality at nine of the 12 species-site combinations, allowing us to estimate site-specific thresholds below which possum population numbers should be reduced and maintained to keep tree mortality under a predetermined level, for example 0.5% per year. The browse model can be used to set site- and species-specific management action thresholds, and can be adapted easily for other plant or herbivore species. Results for multiple plant or herbivore species at a single site can be combined to create conservative, site-wide management strategies, and used to: determine which sites will be affected most by changes in herbivore abundance; quantify thresholds for herbivore management; and justify expenditure on herbivore control. PMID:27066221

  13. Distribution, behavior, and condition of herbivorous fishes on coral reefs track algal resources.

    Science.gov (United States)

    Tootell, Jesse S; Steele, Mark A

    2016-05-01

    Herbivore distribution can impact community structure and ecosystem function. On coral reefs, herbivores are thought to play an important role in promoting coral dominance, but how they are distributed relative to algae is not well known. Here, we evaluated whether the distribution, behavior, and condition of herbivorous fishes correlated with algal resource availability at six sites in the back reef environment of Moorea, French Polynesia. Specifically, we tested the hypotheses that increased algal turf availability would coincide with (1) increased biomass, (2) altered foraging behavior, and (3) increased energy reserves of herbivorous fishes. Fish biomass and algal cover were visually estimated along underwater transects; behavior of herbivorous fishes was quantified by observations of focal individuals; fish were collected to assess their condition; and algal turf production rates were measured on standardized tiles. The best predictor of herbivorous fish biomass was algal turf production, with fish biomass increasing with algal production. Biomass of herbivorous fishes was also negatively related to sea urchin density, suggesting competition for limited resources. Regression models including both algal turf production and urchin density explained 94 % of the variation in herbivorous fish biomass among sites spread over ~20 km. Behavioral observations of the parrotfish Chlorurus sordidus revealed that foraging area increased as algal turf cover decreased. Additionally, energy reserves increased with algal turf production, but declined with herbivorous fish density, implying that algal turf is a limited resource for this species. Our findings support the hypothesis that herbivorous fishes can spatially track algal resources on coral reefs. PMID:26271287

  14. High-Arctic Plant-Herbivore Interactions under Climate Influence

    DEFF Research Database (Denmark)

    Berg, Thomas B.; Schmidt, Niels M.; Høye, Toke Thomas; Aastrup, Peter J.; Hendrichsen, Ditte Katrine; Forchhammer, Mads C.; Klein, David R.

    production of plants indirectly, influenced the spatial distribution of herbivores. Additionally, snow distribution directly affected the distribution of herbivores, and hence, in turn, affected the plant community by selective feeding and locally reducing the standing biomass of forage plants. Although only...... by influencing their access to forage in winter. During winter, musk oxen prefer areas with a thin snow-cover, where food is most easily accessible. In contrast, lemmings seek areas with thick snow-cover, which provide protection from the cold and some predators. Therefore, lemmings may be affected...... few moth larvae were observed at Zackenberg, these had in some cases important local effects owing to their foraging on up to 60% of the flower stands on individual mountain avens. UV-B radiation induces plants to produce secondary plant metabolites, which protects tissues against UV-B damage. This...

  15. 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....... 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...

  16. Risk Assessment and Ecological Effects of Transgenic Bacillus thuringiensis Crops on Non-Target Organisms

    Institute of Scientific and Technical Information of China (English)

    Hui-Lin Yu; Yun-He Li; Kong-Ming Wu

    2011-01-01

    The application of recombinant DNA technology has resulted in many insect-resistant varieties by genetic engineering (GE). Crops expressing Cry toxins derived from Bacillus thuringiensis (Bt) have been planted worldwide, and are an effective tool for pest control. However, one ecological concern regarding the potential effects of insect-resistant GE plants on non-target organisms (NTOs) has been continually debated.In the present study, we briefly summarize the data regarding the development and commercial use of transgenic Bt varieties, elaborate on the procedure and methods for assessing the non-target effects of insect-resistant GE plants, and synthetically analyze the related research results, mostly those published between 2005 and 2010. A mass of laboratory and field studies have shown that the currently available Bt crops have no direct detrimental effects on NTOs due to their narrow spectrum of activity, and Bt crops are increasing the abundance of some beneficial insects and improving the natural control of specific pests. The use of Bt crops, such as Bt maize and Bt cotton, results in significant reductions of insecticide application and clear benefits on the environment and farmer health. Consequently, Bt crops can be a useful component of integrated pest management systems to protect the crop from targeted pests.

  17. Structure of a SusD Homologue, BT1043, Involved in Mucin O-Glycan Utilization in a Prominent Human Gut Symbiont

    Energy Technology Data Exchange (ETDEWEB)

    Koropatkin, Nicole; Martens, Eric C.; Gordon, Jeffrey I.; Smith, Thomas J.; (Danforth); (WU-MED)

    2009-05-21

    Mammalian distal gut bacteria have an expanded capacity to utilize glycans. In the absence of dietary sources, some species rely on host-derived mucosal glycans. The ability of Bacteroides thetaiotaomicron, a prominent human gut symbiont, to forage host glycans contributes to both its ability to persist within an individual host and its ability to be transmitted naturally to new hosts at birth. The molecular basis of host glycan recognition by this species is still unknown but likely occurs through an expanded suite of outermembrane glycan-binding proteins that are the primary interface between B. thetaiotaomicron and its environment. Presented here is the atomic structure of the B. thetaiotaomicron protein BT1043, an outer membrane lipoprotein involved in host glycan metabolism. Despite a lack of detectable amino acid sequence similarity, BT1043 is a structural homologue of the B. thetaiotaomicron starch-binding protein SusD. Both structures are dominated by tetratrico peptide repeats that may facilitate association with outer membrane {beta}-barrel transporters required for glycan uptake. The structure of BT1043 complexed with N-acetyllactosamine reveals that recognition is mediated via hydrogen bonding interactions with the reducing end of {beta}-N-acetylglucosamine, suggesting a role in binding glycans liberated from the mucin polypeptide. This is in contrast to CBM 32 family members that target the terminal nonreducing galactose residue of mucin glycans. The highly articulated glycan-binding pocket of BT1043 suggests that binding of ligands to BT1043 relies more upon interactions with the composite sugar residues than upon overall ligand conformation as previously observed for SusD. The diversity in amino acid sequence level likely reflects early divergence from a common ancestor, while the unique and conserved {alpha}-helical fold the SusD family suggests a similar function in glycan uptake.

  18. 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...

  19. 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...

  20. 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. PMID:25846754

  1. 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

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

    Science.gov (United States)

    Huber, Meret; Epping, Janina; Schulze Gronover, Christian; Fricke, Julia; Aziz, Zohra; Brillatz, Théo; Swyers, Michael; Köllner, Tobias G; Vogel, Heiko; Hammerbacher, Almuth; Triebwasser-Freese, Daniella; Robert, Christelle A M; Verhoeven, Koen; Preite, Veronica; Gershenzon, Jonathan; Erb, Matthias

    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 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. PMID:26731567

  3. 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...

  4. Ant plant herbivore interactions in the neotropical cerrado savanna

    Science.gov (United States)

    Oliveira, Paulo S.; Freitas, André V. L.

    2004-12-01

    The Brazilian cerrado savanna covers nearly 2 million km2 and has a high incidence on foliage of various liquid food sources such as extrafloral nectar and insect exudates. These liquid rewards generate intense ant activity on cerrado foliage, making ant plant herbivore interactions especially prevalent in this biome. We present data on the distribution and abundance of extrafloral nectaries in the woody flora of cerrado communities and in the flora of other habitats worldwide, and stress the relevance of liquid food sources (including hemipteran honeydew) for the ant fauna. Consumption by ants of plant and insect exudates significantly affects the activity of the associated herbivores of cerrado plant species, with varying impacts on the reproductive output of the plants. Experiments with an ant plant butterfly system unequivocally demonstrate that the behavior of both immature and adult lepidopterans is closely related to the use of a risky host plant, where intensive visitation by ants can have a severe impact on caterpillar survival. We discuss recent evidence suggesting that the occurrence of liquid rewards on leaves plays a key role in mediating the foraging ecology of foliage-dwelling ants, and that facultative ant plant mutualisms are important in structuring the community of canopy arthropods. Ant-mediated effects on cerrado herbivore communities can be revealed by experiments performed on wide spatial scales, including many environmental factors such as soil fertility and vegetation structure. We also present some research questions that could be rewarding to investigate in this major neotropical savanna.

  5. 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

  6. 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

  7. Maize Plants Recognize Herbivore-Associated Cues from Caterpillar Frass.

    Science.gov (United States)

    Ray, Swayamjit; Gaffor, Iffa; Acevedo, Flor E; Helms, Anjel; Chuang, Wen-Po; Tooker, John; Felton, Gary W; Luthe, Dawn S

    2015-09-01

    Caterpillar behaviors such as feeding, crawling, and oviposition are known to induce defenses in maize and other plant species. We examined plant defense responses to another important caterpillar behavior, their defecation. Fall armyworms (FAW, Spodoptera frugiperda), a major threat to maize (Zea mays), are voracious eaters and deposit copious amounts of frass in the enclosed whorl tissue surrounding their feeding site, where it remains for long periods of time. FAW frass is composed of molecules derived from the host plant, the insect itself, and associated microbes, and hence provides abundant cues that may alter plant defense responses. We observed that proteins from FAW frass initially induced wound-responsive defense genes in maize; however, a pathogenesis-related (pr) defense gene was induced as the time after application increased. Elicitation of pathogen defenses by frass proteins was correlated with increased herbivore performance and reduced fungal pathogen performance over time. These responses differ from the typical plant response to oral secretions of the FAW. The results pave the way for identification of protein molecule(s) from the excretion of an herbivore that elicits pathogen defense responses while attenuating herbivore defenses in plants. PMID:26306592

  8. Introgression of Bt Genes in Novel Germplasm and Contribution to Indian Cotton Economy

    Institute of Scientific and Technical Information of China (English)

    VIDYASAGAR; Parchuri

    2008-01-01

    Emergence of transgenic Bt-cotton technology has opened up a new chapter in Indian cotton production in 21st century.The cry1Ac gene of Monsanto derived from American Upland Coker-312 background was not directly suitable for varied cotton growing situations in India.Delivery of Bt-gene

  9. A case study for assessment of microbial community dynamics in genetically modified Bt cotton crop fields.

    Science.gov (United States)

    Kapur, Manisha; Bhatia, Ranjana; Pandey, Gunjan; Pandey, Janmejay; Paul, Debarati; Jain, Rakesh K

    2010-08-01

    Bt cotton was the first genetically modified crop approved for use in India. However, only a few studies have been conducted to assess the feasibility of its commercial application. Bt cotton is genetically modified to express a proteinaceous endotoxin (Cry) encoded by cry gene of Bacillus thuringiensis that has specific insecticidal activity against bollworms. Therefore, the amount of pesticides used for growing Bt cotton is postulated to be considerably low as compared to their non-Bt counterparts. Alternatively, it is also speculated that application of a genetically modified crop may alter the bio-geochemical balance of the agriculture field(s). Microbial community composition and dynamics is an important descriptor for assessment of such alterations. In the present study, we have assessed the culturable and non-culturable microbial diversities in Bt cotton and non-Bt cotton soils to determine the ecological consequences of application of Bt cotton. The analyses of microbial community structures indicated that cropping of Bt cotton did not adversely affect the diversity of the microbial communities. PMID:20098990

  10. FARMER DEMAND FOR CORN ROOTWORM BT CORN: DO INSECT RESISTANCE MANAGEMENT GUIDELINES MATTER?

    OpenAIRE

    Langrock, Ines; Terrance M. Hurley; Ostlie, Kenneth

    2003-01-01

    Farmer adoption of Bt corn and compliance with insect resistance management (IRM) regulations will influence the success of these regulations. The purpose of this paper is to use farmer survey data to estimate the demand for new corn rootworm Bt corn and the cost of complying with proposed IRM regulations.

  11. Delta's Key to the TOEFL iBT[R]: Advanced Skill Practice. Revised Edition

    Science.gov (United States)

    Gallagher, Nancy

    2012-01-01

    Delta's Key to the TOEFL iBT: Advanced Skill Practice is a revised and updated edition of Delta's Key to the Next Generation TOEFL Test. Since the introduction of the TOEFL iBT in 2005, there have been significant changes to some of the test questions, particularly the integrated writing and integrated speaking tasks. The new 2011 edition of…

  12. 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

  13. Termites, vertebrate herbivores, and the fruiting success of Acacia drepanolobium.

    Science.gov (United States)

    Brody, Alison K; Palmer, Todd M; Fox-Dobbs, Kena; Doak, Dan F

    2010-02-01

    In African savannas, vertebrate herbivores are often identified as key determinants of plant growth, survivorship, and reproduction. However, plant reproduction is likely to be the product of responses to a suite of abiotic and biotic factors, including nutrient availability and interactions with antagonists and mutualists. In a relatively simple system, we examined the role of termites (which act as ecosystem engineers--modifying physical habitat and creating islands of high soil fertility), vertebrate herbivores, and symbiotic ants, on the fruiting success of a dominant plant, Acacia drepanolobium, in East African savannas. Using observational data, large-scale experimental manipulations, and analysis of foliar N, we found that Acacia drepanolobium trees growing at the edge of termite mounds were more likely to reproduce than those growing farther away, in off-mound soils. Although vertebrate herbivores preferentially used termite mounds as demonstrated by dung deposits, long-term exclusion of mammalian grazers did not significantly reduce A. drepanolobium fruit production. Leaf N was significantly greater in trees growing next to mounds than in those growing farther away, and this pattern was unaffected by exclusion of vertebrates. Thus, soil enrichment by termites, rather than through dung and urine deposition by large herbivores, is of primary importance to fruit production near mounds. Across all mound-herbivore treatment combinations, trees that harbored Crematogaster sjostedti were more likely to fruit than those that harbored one of the other three ant species. Although C. sjostedti is less aggressive than the other ants, it tends to inhabit large, old trees near termite mounds which are more likely to fruit than smaller ones. Termites play a key role in generating patches of nutrient-rich habitat important to the reproductive success of A. drepanolobium in East African savannas. Enhanced nutrient acquisition from termite mounds appears to allow plants to

  14. Pulmoner Hemosiderozisde Toraks BT Bulguları: Olgu Sunumu

    OpenAIRE

    Üner, Abdurrahman; Etlik, Ömer; Uzun, Kürşat; Temizöz, Osman; Gencer, Mehmet; UYGAN, İsmail

    2009-01-01

    SüleymanDemirel Üniversitesi TIP FAKÜLTESİ DERGİSİ: 2000 Mart; 7(1) Pulmoner Hemosiderozisde Toraks BT Bulguları: Olgu Sunumu Abdurrahman Üner, Ömer Etlik, Kürşat Uzun, Osman Temizöz, Mehmet Gencer, İsmail Uygan Özet: İdiopatik pulmoner hemosiderozis (IPH), akciğerde rekurren alveoler hemoraji, hemoptizi atakları ve demir eksikliği anemisi ile karekterize olan bir hastalıktır. Genellikle çocuklarda ve genç adultlarda görülür. İlk kez 4 ay önce öksürükle...

  15. 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

  16. 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...

  17. Belowground induction by delia radicum or phytohormones affect aboveground herbivore communities on field-grown broccoli

    OpenAIRE

    Pierre, S.P.; Dugravot, S.; Hervé, M. R.; Hassan, H M; Dam, N.M. van; Cortesero, A. M.

    2013-01-01

    Induced plant defence in response to phytophagous insects is a well described phenomenon. However, so far little is known about the effect of induced plant responses on subsequently colonizing herbivores in the field. Broccoli plants were induced in the belowground compartment using (i) infestation by the root-herbivore Delia radicum, (ii) root application of jasmonic acid (JA) or (iii) root application of salicylic acid (SA). The abundance of D. radicum and six aboveground herbivores display...

  18. Copper Contamination Impairs Herbivore Initiation of Seaweed Inducible Defenses and Decreases Their Effectiveness

    OpenAIRE

    Warneke, Alexandria M.; Long, Jeremy D.

    2015-01-01

    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 ...

  19. 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...

  20. 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...

  1. Evaluation of Impact of Pollen Grains from Bt, Bt/CpTI Transgenic Cotton and Bt Corn Plants on the Growth and Development of the Mulberry Silkworm, Bombyx mori Linnaeus (Lepidoptera: Bombycidae)

    Institute of Scientific and Technical Information of China (English)

    LI Wen-dong; YE Gong-yin; WU Kong-ming; WANG Xiao-qi; GUO Yu-yuan

    2002-01-01

    The δ-endotoxin genes of Bacillus thuringiensis (Bt) and proteinase inhibitor (PI) genes aretwo kinds of genes popularly used for developing transgenic plants resistant to insect pests. To clarify whetherthere is any risk concerning the effects of pollens from these transgenic crops on non-target insects with eco-nomic importance, such as the effects on the growth and development as well as cocoon quality of the silk-worm, Bombyx mori Linnaeus, a series of feeding experiments were conducted, using pollens from transgeniccotton or corn containing crylAc, cry1A+-CpTI or crylAb genes, compared with pollens from non-transgenicnormal cotton and corn as well as the non-pollen treatment. In contrast to the latter ones, pollens from trans-genic plants showed no significant adverse effects on larval mortality, cocoon weight, pupa weight, cocoonshell weight, pupation rate, emergence rate and fecundity of the silkworm after neonates were fed with thepollens for 72 h. In addition, no dosage effects of pollens were found. Though the duration of 1st instar larvaewas prolonged in the case of feeding with transgenic pollens as compared with those of the non-pollen treat-ment, but they were not significantly different from those fed with pollens from non-transgenic cotton or corn.Meanwhile, the body weight of the 3rd instar molters fed with transgenic pollens was obviously different fromthose for non-pollen treatment, and was all significantly heavier than that of the controls. Consequently, it isconsidered that the adverse effect of pollens from transgenic insect-resistant cotton and corn on the growth anddevelopment of the silkworm is negligible.

  2. 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

  3. Effects of Transgenic Bt Maize on Soil Nutrient Content%转 Bt 基因玉米对土壤养分含量的影响

    Institute of Scientific and Technical Information of China (English)

    景小鹏; 李建东; 周旭梅; 景希强

    2015-01-01

    The transgenic Bt maize Dan BT01 was used as the subjects to study on the effects of transgenic Bt maize on farmland nutrition in different growth periods of seedling stage,jointing stage,huge bellbottom stage, tasseling stage,silking stage and mature stage under field condition.The results showed that oil organic matter content at the tasseling stage and mature stage,total phosphorus content at the silking stage,slowly available potassium concentrations at the huge bellbottom stage and mature stage of transgenic Bt maize were significant-ly higher than the non-transgenic maize,and there was no significant difference of the oil organic matter con-tent,total nitrogen,total phosphorus content and slowly available potassium concentrations at the other growth stages.transgenic Bt maize’s the nitrogen content of the soil hydrolase at the huge bellbottom stage was signif-icantly higher than the non-transgenic maize,at tasseling and silking stage was significantly lower than the non-transgenic maize.Soil nitrate content of transgenic Bt maize at jointing and tasseling is significantly lower than non-transgenic maize,at maturity has significantly increased.Transgenic Bt maize’s soil ammonium ni-trogen in the the huge bellbottom and tasseling stage is significantly lower than non-transgenic maize.From the jointing stage,in addition to the available phosphorus content of the grain-filling stage,non-genetically modi-fied corn available P and K content was significantly higher than transgenic Bt maize.%试验以转 Bt 基因玉米丹 BT01为研究对象,研究了在大田种植条件下转 Bt 基因玉米对苗期、拔节期、大喇叭口期、抽雄期、灌浆期和成熟期土壤养分含量的影响。结果表明,转 Bt 基因玉米抽雄期和成熟期土壤有机质含量,灌浆期全磷含量,大喇叭口期和成熟期缓效钾含量显著高于非转基因玉米,其余生育时期与非转基因玉米的土壤有机质、全氮、

  4. A high-throughput liquid bead array-based screening technology for Bt presence in GMO manipulation.

    Science.gov (United States)

    Fu, Wei; Wang, Huiyu; Wang, Chenguang; Mei, Lin; Lin, Xiangmei; Han, Xueqing; Zhu, Shuifang

    2016-03-15

    The number of species and planting areas of genetically modified organisms (GMOs) has been rapidly developed during the past ten years. For the purpose of GMO inspection, quarantine and manipulation, we have now devised a high-throughput Bt-based GMOs screening method based on the liquid bead array. This novel method is based on the direct competitive recognition between biotinylated antibodies and beads-coupled antigens, searching for Bt presence in samples if it contains Bt Cry1 Aa, Bt Cry1 Ab, Bt Cry1 Ac, Bt Cry1 Ah, Bt Cry1 B, Bt Cry1 C, Bt Cry1 F, Bt Cry2 A, Bt Cry3 or Bt Cry9 C. Our method has a wide GMO species coverage so that more than 90% of the whole commercialized GMO species can be identified throughout the world. Under our optimization, specificity, sensitivity, repeatability and availability validation, the method shows a high specificity and 10-50 ng/mL sensitivity of quantification. We then assessed more than 1800 samples in the field and food market to prove capacity of our method in performing a high throughput screening work for GMO manipulation. Our method offers an applicant platform for further inspection and research on GMO plants. PMID:26499065

  5. Effects of Bt transgenic crops on soil ecosystems: a review of a ten-year research in China

    Institute of Scientific and Technical Information of China (English)

    Wenke LIU

    2009-01-01

    Bacillus thuringiensis (Bt) transgenic cotton is the unique Bt transgenic crop planted on a large scale in China, and its commercialized varieties and hectareage had increased rapidly in China during the past decade (1997-2006) with broad geographic distribution for the economic, environmental, and health benefits. In 2004, the planting area of Bt transgenic cotton in China ranked first worldwide with up to 370 × 106hm2. In addition, Bt transgenic rice varieties in field tests have been close to approval for commercialization. However, ecological risks, a complex issue of Bt transgenic crops on soil ecosystem is urgently faced in China due to more than 60 varieties transferred single or bivalent Bt genes grown under diverse geographic regions. Two main pathways, biomass incorporation and root exudates, are involved in the effects of Bt transgenic crops on soil ecosystems. In this paper, the research results in recent years in China involved in the effects of Bt transgenic crops (Bt transgenic cottons and rice) on soil ecosystems were summarized with special attentions paid to the release and persistence of Bt toxins, and the toxicology to microorganisms, as well as the change of soil biochemical properties in soils where Bt transgenic crops were planted or incubated with their biomass. In addition, the complexity and current research defaults of ecological risk evaluation of Bt transgenic crops in China were highlighted.

  6. Emergence and Abundance of Western Corn Rootworm (Coleoptera: Chrysomelidae) in Bt Cornfields With Structured and Seed Blend Refuges.

    Science.gov (United States)

    Hughson, Sarah A; Spencer, Joseph L

    2015-02-01

    To slow evolution of western corn rootworm (Diabrotica virgifera virgifera LeConte) resistance to Bt (Bacillus thuringiensis Berliner) corn hybrids, non-Bt "refuges" must be planted within or adjacent to Bt cornfields, allowing susceptible insects to develop without exposure to Bt toxins. Bt-susceptible adults from refuges are expected to find and mate with resistant adults that have emerged from Bt corn, reducing the likelihood that Bt-resistant offspring are produced. The spatial and temporal distribution of adults in four refuge treatments (20, 5, and 0% structured refuges and 5% seed blend) and adjacent soybean fields was compared from 2010 to 2012. Adult emergence (adults/trap/day) from refuge corn in structured refuge treatments was greater than that from Bt corn, except during the post-pollination period of corn phenology when emergence from refuge and Bt plants was often the same. Abundance of free-moving adults was greatest in and near refuge rows in structured refuge treatments during vegetative and pollination periods. By post-pollination, adult abundance became evenly distributed. In contrast, adult abundance in 5% seed blends and 0% refuges was evenly distributed, or nearly so, across plots throughout the season. The persistent concentration of adults in refuge rows suggests that structured refuge configurations may not facilitate the expected mixing of adults from refuge and Bt corn. Seed blends produce uniform distributions of adults across the field that may facilitate mating between Bt and refuge adults and ultimately delay the evolution of Bt resistance. PMID:26470111

  7. Cis-mediated down-regulation of a trypsin gene associated with Bt resistance in cotton bollworm

    Science.gov (United States)

    Transgenic plants producing insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are useful for pest control, but their efficacy is reduced when pests evolve resistance. Previously identified mechanisms of resistance to Bt toxins include reduced binding of activated Bt toxins to m...

  8. Differential attraction of parasitoids in relation to specificity of kairomones from herbivores and their by-products

    Institute of Scientific and Technical Information of China (English)

    Sumera Afsheen; Xia Wang; Ran Li; Chuan-Shu Zhu; Yong-Gen Lou

    2008-01-01

    Infochemicals are used by foraging parasitoids in the host selection process from habitat preference until host recognition. Kairomones from the herbivore host plays a vital role in the attraction of parasitoids, particularly in the micro-habitat. Parasitoids are specifically attracted to their respective herbivore species even when different herbivores are present on the same plant. Chemicals emitted from different stages of host (eggs, larvae,pupae, adult), host by-products (e.g., frass, exuviae, mandibular gland secretions, defense secretions etc.), or intra-specific infocbemicals (pheromones) can be main signals for the parasitoids. Parasitoids can differentiate between host and non-host, between different hosts and host stages by perceiving specific volatile and contact kairomones from the host itself,host along with its by-product, by-products alone or intra-specific infochemicals; of which frass (by-product) and intra-specific infochemicals are the most reported ones. Adult and larval parasitoids have been reported to be attracted to kairomones of their target stage or byproduct of their host. Pupal parasitoids have been found to utilize kairomones from the preceding host stage while egg parasitoids are known to exploit a variety of host infochemicals,for example, either from eggs themselves or other non-target host stages, especially adults and adult-related by-products. The kairomonal chemicals identified so far include various groups, but mainly hydrocarbons. A high degree of host specificity and host acceptance is important for the parasitoids as any mistake may result in the loss of fitness.

  9. Mobility of adsorbed Cry1Aa insecticidal toxin from Bacillus thuringiensis (Bt) on montmorillonite measured by fluorescence recovery after photobleaching (FRAP)

    Science.gov (United States)

    Helassa, Nordine; Daudin, Gabrielle; Noinville, Sylvie; Janot, Jean-Marc; Déjardin, Philippe; Staunton, Siobhán; Quiquampoix, Hervé

    2010-06-01

    The insecticidal toxins produced by genetically modified Bt crops are introduced into soil through root exudates and tissue decomposition and adsorb readily on soil components, especially on clays. This immobilisation and the consequent concentration of the toxins in "hot spots" could increase the exposure of soil organisms. Whereas the effects on non-target organisms are well documented, few studies consider the migration of the toxin in soil. In this study, the residual mobility of Bt Cry1Aa insecticidal toxin adsorbed on montmorillonite was assessed using fluorescence recovery after photobleaching (FRAP). This technique, which is usually used to study dynamics of cytoplasmic and membrane molecules in live cells, was applied for the first time to a protein adsorbed on a finely divided swelling clay mineral, montmorillonite. No mobility of adsorbed toxin was observed at any pH and at different degrees of surface saturation.

  10. New Coll-HA/BT composite materials for hard tissue engineering.

    Science.gov (United States)

    Zanfir, Andrei Vlad; Voicu, Georgeta; Busuioc, Cristina; Jinga, Sorin Ion; Albu, Madalina Georgiana; Iordache, Florin

    2016-05-01

    The integration of ceramic powders in composite materials for bone scaffolds can improve the osseointegration process. This work was aimed to the synthesis and characterization of new collagen-hydroxyapatite/barium titanate (Coll-HA/BT) composite materials starting from barium titanate (BT) nanopowder, hydroxyapatite (HA) nanopowder and collagen (Coll) gel. BT nanopowder was produced by combining two wet-chemical approaches, sol-gel and hydrothermal methods. The resulting materials were characterized in terms of phase composition and microstructure by X-ray diffraction, Raman spectroscopy, scanning electron microscopy and transmission electron microscopy. Moreover, the biocompatibility and bioactivity of the composite materials were assessed by in vitro tests. The synthesized BT particles exhibit an average size of around 35nm and a spherical morphology, with a pseudo-cubic or tetragonal symmetry. The diffraction spectra of Coll-HA and Coll-HA/BT composite materials indicate a pronounced interaction between Col and the mineral phases, meaning a good mineralization of Col fibres. As well, the in vitro tests highlight excellent osteoinductive properties for all biological samples, especially for Coll-HA/BT composite materials, fact that can be attributed to the ferromagnetic properties of BT. PMID:26952486

  11. Insect pests management of bt cotton through the manipulation of different eco-friendly techniques

    International Nuclear Information System (INIS)

    This study was designed to manage insect pests of Bt cotton through the manipulation of different eco-friendly techniques. A perusal of data, based on the overall performance of different treatments reflected that lowest population of jassids (0.29) was observed in bio-control treated Bt cotton followed by bio-control treated conventional cotton (0.41). Mean per leaf population of thrips was found lowest in insecticide treated Bt cotton (0.97) which was statically at par with bi-control treated conventional cotton (0.95), biocontrol treated Bt cotton (1.09) and colour traps treated Bt cotton (1.50). In case of white flies, bio-control treated Bt cotton and bio-control treated conventional cotton again proved effective in maintaining the population at lower levels per leaf (0.33 and 0.35 respectively). No bollworms infestation was recorded in transgenic cotton whereas higher attack of the same was observed in the untreated conventional cotton block. The best results were achieved with the application of bio-control agents in combination with Bt cotton resulting in least infestation by insect pests and maximum seed yield of 3657 kg/ha. The population of Chrysoperla carnea was significantly higher in Bt and conventional cotton treated with bio-control agents as compared to the other treatments. The parasitism percentage of Trichogramma chilonis was observed significantly higher in bio-control treated conventional cotton. The studies manifested that combination of bio-control technology with Bt cotton effectively preserves the local beneficial insect fauna indicating its potential to be used as integrated management system against different insect pests of cotton. (author)

  12. Potential Benefits of Bt Brinjal in India — An Economic Assessment

    OpenAIRE

    Kumar, Sant; Lakshmi Prasanna, P.A.; Wankhade, Shwetal

    2011-01-01

    The potential economic benefits of Bt brinjal hybrids in terms of yield gain, reduction in insecticide-use, and increase in net returns per hectare have been reported in this study. Results have shown that adoption of Bt brinjal hybrids would provide yield gain of 37 per cent and reduction in total insecticide-use of about 42 per cent over non-Bt hybrids. Other benefits like increase in additional brinjal production (30 thousand tonnes), savings from insecticides (` 47 crore) against Fruit an...

  13. Introgression of Bt Genes in Novel Germplasm and Contribution to Indian Cotton Economy

    Institute of Scientific and Technical Information of China (English)

    VIDYASAGAR Parchuri

    2008-01-01

    @@ Emergence of transgenic Bt-cotton technology has opened up a new chapter in Indian cotton production in 21st century.The crylAc gene of Monsanto derived from American Upland Coker-312 background was not directly suitable for varied cotton growing situations in India.Delivery of Bt-gene technology to Indian farming systems should be superimposed on hybrid technology,fiber quality,and superior agronomic adaptation.Protection offered by this alien Bt-gene against major serious pest Helicoverpa armigera,by preventing annual losses ranging from 15~35 percent,automaticaly contributed to higher yield.

  14. Review - Host specificity of insect herbivores in tropical forests

    Czech Academy of Sciences Publication Activity Database

    Novotný, Vojtěch; Basset, Y.

    2005-01-01

    Roč. 272, č. 1568 (2005), s. 1083-1090. ISSN 0962-8452 R&D Projects: GA AV ČR(CZ) IAA6007106; GA ČR(CZ) GD206/03/H034; GA ČR(CZ) GA206/04/0725; GA MŠk(CZ) ME 646 Grant ostatní: US Nationals Science Foundation(US) DEB-02-11591; Darwin Initiative for the Survival of Species(US) 162/10/030 Institutional research plan: CEZ:AV0Z50070508 Keywords : food web * herbivore guild * host plant range Subject RIV: EH - Ecology, Behaviour Impact factor: 3.510, year: 2005

  15. Resistance evolution to Bt crops: predispersal mating of European corn borers.

    Directory of Open Access Journals (Sweden)

    Ambroise Dalecky

    2006-06-01

    Full Text Available Over the past decade, the high-dose refuge (HDR strategy, aimed at delaying the evolution of pest resistance to Bacillus thuringiensis (Bt toxins produced by transgenic crops, became mandatory in the United States and is being discussed for Europe. However, precopulatory dispersal and the mating rate between resident and immigrant individuals, two features influencing the efficiency of this strategy, have seldom been quantified in pests targeted by these toxins. We combined mark-recapture and biogeochemical marking over three breeding seasons to quantify these features directly in natural populations of Ostrinia nubilalis, a major lepidopteran corn pest. At the local scale, resident females mated regardless of males having dispersed beforehand or not, as assumed in the HDR strategy. Accordingly, 0-67% of resident females mating before dispersal did so with resident males, this percentage depending on the local proportion of resident males (0% to 67.2%. However, resident males rarely mated with immigrant females (which mostly arrived mated, the fraction of females mating before dispersal was variable and sometimes substantial (4.8% to 56.8%, and there was no evidence for male premating dispersal being higher. Hence, O. nubilalis probably mates at a more restricted spatial scale than previously assumed, a feature that may decrease the efficiency of the HDR strategy under certain circumstances, depending for example on crop rotation practices.

  16. 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

  17. 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.

  18. The Effects of Plant Compensatory Regrowth and Induced Resistance on Herbivore Population Dynamics.

    Science.gov (United States)

    Stieha, Christopher R; Abbott, Karen C; Poveda, Katja

    2016-02-01

    Outbreaks of herbivorous insects are detrimental to natural and agricultural systems, but the mechanisms driving outbreaks are not well understood. Plant responses to herbivory have the potential to produce outbreaks, but long-term effects of plant responses on herbivore dynamics are understudied. To quantify these effects, we analyze mathematical models of univoltine herbivores consuming annual plants with two responses: (1) compensatory regrowth, which affects herbivore survival in food-limited situations by increasing the amount of food available to the herbivore; and (2) induced resistance, which reduces herbivore survival proportional to the strength of the response. Compensatory regrowth includes tolerance, where plants replace some or all of the consumed biomass, and overcompensation, where plants produce more biomass than was consumed. We found that overcompensation can cause bounded fluctuations in the herbivore density (called outbreaks here) by itself, whereas neither tolerance nor induced resistance can cause an outbreak on its own. Food limitation and induced resistance can also drive outbreaks when they act simultaneously. Tolerance damps these outbreaks, but overcompensation, by contrast, qualitatively changes the conditions under which the outbreaks occur. Not properly accounting for these interactions may explain why it has been difficult to document plant-driven insect outbreaks and could undermine efforts to control herbivore populations in agricultural systems. PMID:26807745

  19. 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

  20. 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

  1. 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.

  2. 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

  3. 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

  4. 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

  5. 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

  6. 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

  7. Species-specific defence responses facilitate conspecifics and inhibit heterospecifics in above–belowground herbivore interactions

    OpenAIRE

    Huang, Wei; Siemann, Evan; Xiao, Li; Yang, Xuefang; Ding, Jianqing

    2014-01-01

    Conspecific and heterospecific aboveground and belowground herbivores often occur together in nature and their interactions may determine community structure. Here we show how aboveground adults and belowground larvae of the tallow tree specialist beetle Bikasha collaris and multiple heterospecific aboveground species interact to determine herbivore performance. Conspecific aboveground adults facilitate belowground larvae, but other aboveground damage inhibits larvae or has no effect. Belowgr...

  8. The Root Herbivore History of the Soil Affects the Productivity of a Grassland Plant Community and Determines Plant Response to New Root Herbivore Attack

    OpenAIRE

    Sonnemann, Ilja; Hempel, Stefan; Beutel, Maria; Hanauer, Nicola; Reidinger, Stefan; Wurst, Susanne

    2013-01-01

    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...

  9. Bt Maize Seed Mixtures for Helicoverpa zea (Lepidoptera: Noctuidae): Larval Movement, Development, and Survival on Non-transgenic Maize.

    Science.gov (United States)

    Burkness, Eric C; Cira, T M; Moser, S E; Hutchison, W D

    2015-12-01

    In 2012 and 2013, field trials were conducted near Rosemount, MN, to assess the movement and development of Helicoverpa zea (Boddie) larvae on non-Bt refuge corn plants within a seed mixture of non-Bt and Bt corn. The Bt corn hybrid expressed three Bt toxins-Cry1Ab, Cry1F, and Vip3A. As the use of seed mixtures for insect resistance management (IRM) continues to be implemented, it is necessary to further characterize how this IRM approach impacts resistance development in ear-feeding Lepidopteran pests. The potential for Bt pollen movement and cross pollination of the non-Bt ears in a seed mixture may lead to Bt toxin exposure to larvae developing on those refuge ears. Larval movement and development by H. zea, feeding on non-Bt refuge plants adjacent to either transgenic Bt or non-Bt plants, were measured to investigate the potential for unintended Bt exposure. Non-Bt plants were infested with H. zea eggs and subplots were destructively sampled twice per week within each treatment to assess larval development, location, and kernel injury. Results indicate that H. zea larval movement between plants is relatively low, ranging from 2-16% of larvae, and occurs mainly after reaching the second instar. Refuge plants in seed mixtures did not produce equivalent numbers of H. zea larvae, kernel injury, and larval development differed as compared with a pure stand of non-Bt plants. This suggests that there may be costs to larvae developing on refuge plants within seed mixtures and additional studies are warranted to define potential impacts. PMID:26318006

  10. Evidence of field-evolved resistance of Spodoptera frugiperda to Bt corn expressing Cry1F in Brazil that is still sensitive to modified Bt toxins.

    Directory of Open Access Journals (Sweden)

    Rose Monnerat

    Full Text Available Brazil ranked second only to the United States in hectares planted to genetically modified crops in 2013. Recently corn producers in the Cerrado region reported that the control of Spodoptera frugiperda with Bt corn expressing Cry1Fa has decreased, forcing them to use chemicals to reduce the damage caused by this insect pest. A colony of S. frugiperda was established from individuals collected in 2013 from Cry1Fa corn plants (SfBt in Brazil and shown to have at least more than ten-fold higher resistance levels compared with a susceptible colony (Sflab. Laboratory assays on corn leaves showed that in contrast to SfLab population, the SfBt larvae were able to survive by feeding on Cry1Fa corn leaves. The SfBt population was maintained without selection for eight generations and shown to maintain high levels of resistance to Cry1Fa toxin. SfBt showed higher cross-resistance to Cry1Aa than to Cry1Ab or Cry1Ac toxins. As previously reported, Cry1A toxins competed the binding of Cry1Fa to brush border membrane vesicles (BBMV from SfLab insects, explaining cross-resistance to Cry1A toxins. In contrast Cry2A toxins did not compete Cry1Fa binding to SfLab-BBMV and no cross-resistance to Cry2A was observed, although Cry2A toxins show low toxicity to S. frugiperda. Bioassays with Cry1AbMod and Cry1AcMod show that they are highly active against both the SfLab and the SfBt populations. The bioassay data reported here show that insects collected from Cry1Fa corn in the Cerrado region were resistant to Cry1Fa suggesting that resistance contributed to field failures of Cry1Fa corn to control S. frugiperda.

  11. Evidence of field-evolved resistance of Spodoptera frugiperda to Bt corn expressing Cry1F in Brazil that is still sensitive to modified Bt toxins.

    Science.gov (United States)

    Monnerat, Rose; Martins, Erica; Macedo, Cristina; Queiroz, Paulo; Praça, Lilian; Soares, Carlos Marcelo; Moreira, Helio; Grisi, Isabella; Silva, Joseane; Soberon, Mario; Bravo, Alejandra

    2015-01-01

    Brazil ranked second only to the United States in hectares planted to genetically modified crops in 2013. Recently corn producers in the Cerrado region reported that the control of Spodoptera frugiperda with Bt corn expressing Cry1Fa has decreased, forcing them to use chemicals to reduce the damage caused by this insect pest. A colony of S. frugiperda was established from individuals collected in 2013 from Cry1Fa corn plants (SfBt) in Brazil and shown to have at least more than ten-fold higher resistance levels compared with a susceptible colony (Sflab). Laboratory assays on corn leaves showed that in contrast to SfLab population, the SfBt larvae were able to survive by feeding on Cry1Fa corn leaves. The SfBt population was maintained without selection for eight generations and shown to maintain high levels of resistance to Cry1Fa toxin. SfBt showed higher cross-resistance to Cry1Aa than to Cry1Ab or Cry1Ac toxins. As previously reported, Cry1A toxins competed the binding of Cry1Fa to brush border membrane vesicles (BBMV) from SfLab insects, explaining cross-resistance to Cry1A toxins. In contrast Cry2A toxins did not compete Cry1Fa binding to SfLab-BBMV and no cross-resistance to Cry2A was observed, although Cry2A toxins show low toxicity to S. frugiperda. Bioassays with Cry1AbMod and Cry1AcMod show that they are highly active against both the SfLab and the SfBt populations. The bioassay data reported here show that insects collected from Cry1Fa corn in the Cerrado region were resistant to Cry1Fa suggesting that resistance contributed to field failures of Cry1Fa corn to control S. frugiperda. PMID:25830928

  12. 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...

  13. 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.

  14. 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.

  15. 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

  16. 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.

  17. 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.

  18. Herbivores alter the fitness benefits of a plant-rhizobium mutualism

    Science.gov (United States)

    Heath, Katy D.; Lau, Jennifer A.

    2011-03-01

    Mutualisms are best understood from a community perspective, since third-party species have the potential to shift the costs and benefits in interspecific interactions. We manipulated plant genotypes, the presence of rhizobium mutualists, and the presence of a generalist herbivore and assessed the performance of all players in order to test whether antagonists might alter the fitness benefits of plant-rhizobium mutualism, and vice versa how mutualists might alter the fitness consequences of plant-herbivore antagonism. We found that plants in our experiment formed more associations with rhizobia (root nodules) in the presence of herbivores, thereby increasing the fitness benefits of mutualism for rhizobia. In contrast, the effects of rhizobia on herbivores were weak. Our data support a community-dependent view of these ecological interactions, and suggest that consideration of the aboveground herbivore community can inform ecological and evolutionary studies of legume-rhizobium interactions.

  19. A decade of Bt cotton in Chinese fields: Assessing the direct effects and indirect externalities of Bt cotton adoption in China

    Institute of Scientific and Technical Information of China (English)

    Scott; ROZELLE; Carl; PRAY

    2010-01-01

    The objective of this study is to examine whether or not the gains from reduced spraying for bollworms are being sustained more than one decade after the initial adoption in 2007. Based on farm-level data collected by the authors in 1999–2007 in 16 villages from 4 provinces, this study shows that insecticides applied for controlling bollworms have declined. This analysis supports Chinese policy makers’ decision to not require refuges of non-Bt cotton fields. It also suggests that past studies may have underestimated the benefits from adopting Bt technology.

  20. Adoption of Bt Cotton: Threats and Challenges Adopción de Algodón Bt: Desafíos y Amenazas

    Directory of Open Access Journals (Sweden)

    Muhammad Faisal Bilal

    2012-09-01

    Full Text Available Adopting new technology always involves advantages and risks; Bt cotton (Gossypium hirsutum L. is a new technology well known in developed countries for its many advantages, such as reduced pesticide application, better insect pest control, and higher lint yield. However, its success in developing countries is still a question mark. Global adoption of Bt cotton has risen dramatically from 0.76 million ha when introduced in 1996 to 7.85 million ha in the 2005 cotton-growing season where 54% of the cotton crops in the USA, 76% in China, and 80% in Australia were grown with single or multiple Bt genes. Bollworms are serious cotton pests causing 30-40% yield reduction in Pakistan and 20-66% potential crop losses in India. The major advances shown in this review include: (1 Evolution of Bt cotton may prove to be a green revolution to enhance cotton yield; (2 adoption of Bt cotton by farmers is increasing due to its beneficial environmental effects by reducing pesticide application: however, a high seed price has compelled farmers to use illegal non-approved Bt causing huge damage to crops because of low tolerance to insect pests; and (3 some factors responsible for changes in the efficiency of the Bt gene and Bt cotton yield include internal phenology (genetics, atmospheric changes (CO2 concentration, nutrition, insect pests, boll distribution pattern, disease and nematodes, removal of fruiting branch and/or floral bud, introduction of Bt gene, and terpenoids and tannin production in the plant body.La adopción de nueva tecnología siempre involucra ventajas y riesgos; algodón Bt (Gossypium hirsutum L. es una nueva tecnología bien conocida en países desarrollados por muchas ventajas como reducida aplicación de pesticidas, mejor control de insectos plaga, y mayor producción de fibra, pero su éxito en países en desarrollo aún conlleva dudas. La adopción global de algodón Bt ha aumentado dramáticamente de 0,76 millones de hectáreas en su

  1. Adoption of Bt Cotton: Threats and Challenges Adopción de Algodón Bt: Desafíos y Amenazas

    OpenAIRE

    Muhammad Faisal Bilal; Muhammad Farrukh Saleem; Muhammad Ashfaq Wahid; Amir Shakeel; Mudassar Maqbool

    2012-01-01

    Adopting new technology always involves advantages and risks; Bt cotton (Gossypium hirsutum L.) is a new technology well known in developed countries for its many advantages, such as reduced pesticide application, better insect pest control, and higher lint yield. However, its success in developing countries is still a question mark. Global adoption of Bt cotton has risen dramatically from 0.76 million ha when introduced in 1996 to 7.85 million ha in the 2005 cotton-growing season where 54% o...

  2. The adoption of Bt-maize in Germany: An econometric analysis

    OpenAIRE

    Consmuller, Nicola; Beckmann, Volker; Petrick, Martin

    2009-01-01

    In this study, we theoretically and empirically investigate the determinants of Bt-maize adoption in German regions. Specifically, we ask how the regulatory framework, the farm structures as well as the socio-political environment of GM expansion in Germany have influenced regional adoption rates. Following a description of the relevant legal and economic framework in Germany, we develop theoretical hypotheses concerning regional variation in Bt-maize adoption and test them econometrically wi...

  3. Apparent digestibility coefficients and consumption of corn silage with and without Bt gene in sheep

    OpenAIRE

    Camila Memari Trava; Mauro Sartori Bueno; Geraldo Balieiro

    2012-01-01

    Corn silage is the most important preserved food for ruminants. The transgenic corn was inserted into the genetic code Bt gene (Bacillus thuringiensis) that expresses a toxic protein to caterpillars pests of maize, reducing production costs. To evaluate the varieties of plant corn silage DKB and AG with or without the Bt gene on the voluntary intake of DM (g/day) and apparent digestibility coefficients (CDA) of nutrients in sheep, the experiment was conducted at the Institute of Animal Scienc...

  4. The recovery of Bt toxin content after temperature stress termination in transgenic cotton

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Y.; Wen, Y.; Zhang, X.; Wang, Y.; Chen, D.

    2013-06-01

    The insecticidal efficacy of Bt cotton under different environments has generated controversy in recent years. The objective of this study was to investigate possible reasons of the conflicting results caused by temperature stress. Two different types of Bt transgenic cotton cultivars (a Bt cultivar, Sikang1, and an hybrid Bt cultivar, Sikang3) were selected. The plants of the two Bt cultivars were exposed to high temperature (37 degree centigrade), low temperature (18 degree centigrade), and the control (27 degree centigrade) for short (24 h) and long (48 h) periods of stress at peak boll stage, and then moved to the glasshouse where the control plants were maintained. The results showed that the leaf insecticidal toxin content fully recovered within 24 h to the level of control after the end of short duration high-temperature treatment, and recovered mostly within 48 h of the termination of 24 h low-temperature stress. Under long duration high temperature treatment the Bt toxin content required longer recovery periods (48 and 72 h for Sikang3 and Sikang1, respectively) to reach the control level. The Bt protein content only recovered partially at 96 h after the end of the long-duration low-temperature stress, and the concentrations of the Cry1Ac protein were 74% and 77% of the corresponding control for Sikang1 and Sikang3, respectively. The different recovery and increase slowly of the leaf nitrogen metabolic rates after ceasing the heat and cold stress may be possible reason for the above difference. In summary, the duration and type of temperature (cold or heat) stress may cause different Bt insecticidal protein recovery rate due to different recovery rate of enzymes. (Author) 31 refs.

  5. Is Monsanto Leaving Money on the Table? Monopoly Pricing and Bt Cotton Value with Heterogeneous Adopters

    OpenAIRE

    Oehmke, James F.; Wolf, Christopher A.

    2004-01-01

    We examine the allocation of technology rents between a price-setting, innovating monopolist and heterogeneous technology adopters. A model of monopoly pricing in the presence of heterogeneous adopters is used to examine conditions under which greater producer (farmer) heterogeneity leads to greater producer benefit from innovation in non-competitive markets. An application to Bt cotton determines the profit-maximizing price of Bt cotton seed and reveals that Monsanto and Delta and Pine Land ...

  6. The emergence of insect resistance in Bt-corn: implication of resistance management information under uncertainty

    OpenAIRE

    Linacre, Nicholas A.; Thompson, Colin J.

    2005-01-01

    "The successful management of transgenic technology is likely to depend on the economic behavioral response of farmers to the regulated use of transgenic crops. A well-studied example is the widespread use of Bt-corn, in the United States, and elsewhere, to control the European Corn Borer, a major corn pest. The extensive use of Bt-corn has led to concerns about the emergence of insect resistance. The United States Environment Protection Agency addressed this potential problem by developing a...

  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. FROM Qutn TO Bt COTTON: DEVELOPMENT, ADOPTION AND PROSPECTS. A REVIEW.

    Science.gov (United States)

    Maik, W; Abid, M A; Cheema, H M N; Khan, A A; Iqbal, M Z; Qayyum, A; Hanif, M; Bibi, N; Yuan, S N; Yasmeen, A; Mahmood, A; Ashraf, J

    2015-01-01

    Cotton has unique history of domestication, diversification, and utilization. Globally it is an important cash crop that provides raw material for textile industry. The story of cotton started from human civilization and the climax arrived with the efforts of developing transgenic cotton for various traits. Though conventional breeding brought steady improvement in developing resistance against biotic stresses but recent success story of gene transferfrom Bacillus thuringiensis into cotton showed game changing effects on cotton cultivation. Amongst various families of insecticidal proteins Bt Cry-toxins received more attention because of specificity against receptors on the cell membranes of insect midgut epithelial cells. Rapid Bt cotton adoption by farmers due to its economic and environmental benefits has changed the landscape of cotton cultivation in many countries. But the variable expression of Bt transgene in the newly developed Bt cotton genotypes in tropical environment is questionable. Variability of toxin level in different plant parts at various life stage of plant is an outcome of genotypic interaction with environmental factors. Temporal gene expression of Cry1Ac is also blamed for the epigenetic background in which transgene has been inserted. The presence of genotypes with sub-lethal level of Bt toxin might create resistance in Lepidopteron insects, limiting the use of Bt cotton in future, with the opportunityfor other resistance development strategies to get more attention like gene stacking. Until the farmers get access to more recent technology, best option is to delay the development of resistance by applying Insect Resistance Management (IRM) strategies. PMID:26841496

  9. Preparative Purification and Bioassay of Bt Toxin from Cry1Ab Transgenic Rice

    Institute of Scientific and Technical Information of China (English)

    WU Jian-min; YE Qin-fu

    2004-01-01

    A method of extracting and purifying Cry1Ab protein(Bt toxin) from Cry1Ab transgenic rice was established. Most of the Bt toxin present in the tissue of Cry1Ab transgenic rice was extracted effectively with a solution of 50 mmol/LNa2CO3 and NaHCO3. The crude protein containing Bt toxin was obtained after the pretreatment of Cry1Ab transgenic rice with ultra-filtration, ammonium sulfate precipitation and centrifugation. The dialysed crude protein was futher separated on DEAE Sephadex A-50 columns and Sephadex G-150 columns. The protein bound on DEAE Sephadex A-50 gel was eluted with buffer solution B(10 mmol/L trisHCl buffer+1. 0 mmol/L EDTA, pH=8.0) mixed with 0. 1, 0. 3, 0. 5 and 0. 8 mol/L NaCl in a discontinuous gradient elution mode. The peak of the Bt toxin eluted from the columns was identified by ELISA and bioassayed with larvae of tobacco hornworms and silkworms. The purity and the bioactivity of the Bt toxin were determined by means of SDS-PAGE and larvicidal assay, respectively. The purity of the Bt toxin obtained by this method is high, and its insecticidal activity is retained after the toxin is purified.

  10. Development of Insect-Resistant Hybrid Rice by Introgressing the Bt Gene from Bt Rice Huahui 1 into II-32A/B, a Widely Used Cytogenic Male Sterile System

    Institute of Scientific and Technical Information of China (English)

    LAI Yun-song; HUANG Hai-qing; XU Meng-yun; WANG Liang-chao; ZHANG Xiao-bo; ZHANG Ji-wen; TU Ju-min

    2014-01-01

    Huahui 1 is an elite transgenic male sterile restorer line of wild rice abortive-type that expresses a Bacillus thuringiensis (Bt)δ-endotoxin and provides effective and economic control of lepidopteran insects. To exploit Huahui 1 to develop a new Bt rice, the insertion site of the Bt gene was determined by thermal asymmetric interlaced PCR (TAIL-PCR). Bt was located in the promoter region of LOC.Os10g10360, approximately 5.35 Mb from the telomere of the short arm of chromosome 10. For the ifrst time, a Bt cytoplasmic male sterile (CMS) system was developed by introgressing Bt from Huahui 1. The recipient CMS system used consisted of Indonesia paddy rice-type II-32B (maintainer line) and II-32A (male sterile line). Marker-assisted selection was used to increase selection efifciency in the backcrossing program. In BC5F1, the Bt plant 85015-8 was selected for further analyses, as it had the highest SSR marker homozygosity. In addition, the linkage drag of the foreign Bt gene in 85015-8 was minimized to 8.01-11.46 Mb. The foreign Bt gene was then delivered from 85015-8 into II-32A. The resultant Bt II-32A and Bt II-32B lines were both resistant to lepidopteran in ifeld trials, and agronomic traits were not disturbed. The maintainability of II-32B, and the male sterility and general combining ability of II-32A, were not affected by the Bt introgression. This study demonstrates a simple and fast approach to develop Bt hybrid rice.

  11. Aspects of a two-pasture — herbivore model

    Directory of Open Access Journals (Sweden)

    Jan Åge Riseth

    2004-04-01

    Full Text Available Pastures for reindeer can be divided into green pastures (mainly herbs and grasses of summer time and more or less snow-covered lichen pastures of winter. Fall and spring pastures have a composition in-between these extremes, but for model purposes bisection is sufficient. For the animals the green-pasture season is an anabolic phase with a physiological building-up of protein reserves, while winter is a catabolic phase where food-intake is reduced and the animals to a considerable extent survive on the accumulated reserves from summer. While protein reserves are stored from summer to winter, lichen pastures are stored from year to year. Grasses and herbs not being grazed are wilting by the end of the growing season, while lichens not grazed can live for many years. This corresponds with fundamental differences in both growth pattern and resilience. The implications of the different features, and their interconnections, are not easy to survey without formal modeling. The point of departure is a simple pasture-herbivore model, well known from the literature building on a set of differential equations. A new two-pasture-herbivore model is developed. The model includes as basic elements the Klein (1968 hypothesis and that a residual lichen biomass is kept ungrazed due to snow-cover protection. Further the annual cycle is divided into four stylized seasons with herd rates of winter survival, spring calving, summer physiological growth and fall slaughtering. Isoclines are derived for summer pasture, winter pasture and herbivores. Stability properties are discussed in relation to various situations of seasonal pasture balance. Empirical examples, particularly that of changes in pasture balance and vegetation cover in Western Finnmark, Norway, are discussed. The article finds that the two-pasture model provides important features of reality, such as the stability aspects of pasture balance, which cannot be displayed by a one-pasture model. It is

  12. Longer resistance of some DNA traits from BT176 maize to gastric juice from gastrointestinal affected patients.

    Science.gov (United States)

    Ferrini, A M; Mannoni, V; Pontieri, E; Pourshaban, M

    2007-01-01

    The presence of antibiotic resistance marker genes in genetically engineered plants is one of the most controversial issues related to Genetically Modified Organism (GMO)-containing food, raising concern about the possibility that these markers could increase the pool of antibiotic resistance genes. This study investigates the in vitro survival of genes bla and cryIA(b) of maize Bt176 in human gastric juice samples. Five samples of gastric juice were collected from patients affected by gastro-esophageal reflux or celiac disease and three additional samples were obtained by pH modification with NaHCO3. DNA was extracted from maize Bt176 and incubated with samples of gastric juices at different times. The survival of the target traits (bla gene, whole 1914 bp gene cry1A(b), and its 211 bp fragment) was determined using PCR. The stability of the target genes was an inverse function of their lengths in all the samples. Survival in samples from untreated subjects was below the normal physiological time of gastric digestion. On the contrary, survival time in samples from patients under anti-acid drug treatment or in samples whose pH was modified, resulted strongly increased. Our data indicate the possibility that in particular cases the survival time could be so delayed that, as a consequence, some traits of DNA could reach the intestine. In general, this aspect must be considered for vulnerable consumers (people suffering from gastrointestinal diseases related to altered digestive functionality, physiological problems or drug side-effects) in the risk analysis usually referred to healthy subjects. PMID:17346434

  13. Does Content Knowledge Affect TOEFL iBT[TM] Reading Performance? A Confirmatory Approach to Differential Item Functioning. TOEFL iBT Research Report. RR-09-29

    Science.gov (United States)

    Liu, Ou Lydia; Schedl, Mary; Malloy, Jeanne; Kong, Nan

    2009-01-01

    The TOEFL iBT[TM] has increased the length of the reading passages in the reading section compared to the passages on the TOEFL[R] computer-based test (CBT) to better approximate academic reading in North American universities, resulting in a reduced number of passages in the reading test. A concern arising from this change is whether the decrease…

  14. Criterion-Related Validity of the TOEFL iBT Listening Section. TOEFL iBT Research Report. RR-09-02

    Science.gov (United States)

    Sawaki, Yasuyo; Nissan, Susan

    2009-01-01

    The study investigated the criterion-related validity of the "Test of English as a Foreign Language"[TM] Internet-based test (TOEFL[R] iBT) Listening section by examining its relationship to a criterion measure designed to reflect language-use tasks that university students encounter in everyday academic life: listening to academic lectures. The…

  15. Bistand til risikovurdering Supplerende oplysninger fra Syngenta Seeds om overvågningsplanen (evt. ændret risikovurdering). Zea mays (Bt11). Supplerende materiale om Bt11

    DEFF Research Database (Denmark)

    Kjellsson, Gøsta; Strandberg, Morten Tune; Damgaard, Christian

    2005-01-01

    "Mail: Den supplerende information om Bt-11 majsen (C/F/96/05-10) der er modtaget d. 02-03-2005, indeholder en ny udgave af den generelle overvågningsplan med enkelte ændringer (forbedringer) i forhold til forrige udgave (kommenteret 24-02-2005). Vi har ikke fundet nogen nye oplysninger der ændre...

  16. Competitive release and outbreaks of non-target pests associated with transgenic Bt cotton

    Science.gov (United States)

    This study tests a competitive release hypothesis that Helicoverpa zea larval herbivory will 1) deter oviposition and increase leaving rates of the stink bugs, Euchistus servus and Nezara viridula and that 2) that these effects will be stronger for E. servus than for N. viridula. By spatially separa...

  17. Decaying toxic wood as sodium supplement for herbivorous mammals in Gabon.

    Science.gov (United States)

    Iwata, Yuji; Nakashima, Yoshihiro; Tsuchida, Sayaka; Nguema, Pierre Philippe Mbehang; Ando, Chieko; Ushida, Kazunari; Yamagiwa, Juichi

    2015-10-01

    African rainforest harbors herbivores at high density. However, because plants and soils typically lack in some essential minerals, rainforest is not always a suitable habitat for herbivores. How they fulfill the mineral requirements is therefore an important question to animal ecology and conservation. Although large marshes, called 'bais', are often mentioned as efficient mineral-resource, little information on other sodium resources has still been available. Our laboratory works and field surveys found that a peculiar item, decaying wood stumps of Anthostema aubryanum, played as a major sodium resource for herbivores in Moukalaba-Doudou National Park, Gabon. When A. aubryanum is alive, the sodium content of its bark is low and its latex is toxic. Sodium is accumulated in decaying stumps (mean=1,343 mg/kg dry matter). Eight herbivores visited stumps to ingest the dead wood. Fecal sample analysis revealed that western lowland gorillas, a species most-frequently using the stumps, consumed large amount of the dead wood as regular food. Our findings suggest that decaying A. aubryanum is critical sodium-resources and is a key species for herbivores in our study area. Importance of the A. aubryanum may be particularly large there, because it is a limited sodium-rich material that is available year round. Our study site is known as the site where the densities of several herbivores are among the highest at Central Africa. The relatively high herbivores density in our study site may partly depend on decaying A. aubryanum as sodium resources. PMID:25994487

  18. The genome of Tetranychus urticae reveals herbivorous pest adaptations

    Science.gov (United States)

    Grbić, Miodrag; Van Leeuwen, Thomas; Clark, Richard M.; Rombauts, Stephane; Rouzé, Pierre; Grbić, Vojislava; Osborne, Edward J.; Dermauw, Wannes; Ngoc, Phuong Cao Thi; Ortego, Félix; Hernández-Crespo, Pedro; Diaz, Isabel; Martinez, Manuel; Navajas, Maria; Sucena, Élio; Magalhães, Sara; Nagy, Lisa; Pace, Ryan M.; Djuranović, Sergej; Smagghe, Guy; Iga, Masatoshi; Christiaens, Olivier; Veenstra, Jan A.; Ewer, John; Villalobos, Rodrigo Mancilla; Hutter, Jeffrey L.; Hudson, Stephen D.; Velez, Marisela; Yi, Soojin V.; Zeng, Jia; Pires-daSilva, Andre; Roch, Fernando; Cazaux, Marc; Navarro, Marie; Zhurov, Vladimir; Acevedo, Gustavo; Bjelica, Anica; Fawcett, Jeffrey A.; Bonnet, Eric; Martens, Cindy; Baele, Guy; Wissler, Lothar; Sanchez-Rodriguez, Aminael; Tirry, Luc; Blais, Catherine; Demeestere, Kristof; Henz, Stefan R.; Gregory, T. Ryan; Mathieu, Johannes; Verdon, Lou; Farinelli, Laurent; Schmutz, Jeremy; Lindquist, Erika; Feyereisen, René; Van de Peer, Yves

    2016-01-01

    The spider mite Tetranychus urticae is a cosmopolitan agricultural pest with an extensive host plant range and an extreme record of pesticide resistance. Here we present the completely sequenced and annotated spider mite genome, representing the first complete chelicerate genome. At 90 megabases T. urticae has the smallest sequenced arthropod genome. Compared with other arthropods, the spider mite genome shows unique changes in the hormonal environment and organization of the Hox complex, and also reveals evolutionary innovation of silk production. We find strong signatures of polyphagy and detoxification in gene families associated with feeding on different hosts and in new gene families acquired by lateral gene transfer. Deep transcriptome analysis of mites feeding on different plants shows how this pest responds to a changing host environment. The T. urticae genome thus offers new insights into arthropod evolution and plant–herbivore interactions, and provides unique opportunities for developing novel plant protection strategies. PMID:22113690

  19. Botanical insecticides inspired by plant-herbivore chemical interactions.

    Science.gov (United States)

    Miresmailli, Saber; Isman, Murray B

    2014-01-01

    Plants have evolved a plethora of secondary chemicals to protect themselves against herbivores and pathogens, some of which have been used historically for pest management. The extraction methods used by industry render many phytochemicals ineffective as insecticides despite their bioactivity in the natural context. In this review, we examine how plants use their secondary chemicals in nature and compare this with how they are used as insecticides to understand why the efficacy of botanical insecticides can be so variable. If the commercial production of botanical insecticides is to become a viable pest management option, factors such as production cost, resource availability, and extraction and formulation techniques need be considered alongside innovative application technologies to ensure consistent efficacy of botanical insecticides. PMID:24216132

  20. Soil microflora and enzyme activities in rhizosphere of Transgenic Bt cotton hybrid under different intercropping systems and plant protection schedules

    Science.gov (United States)

    Biradar, D. P.; Alagawadi, A. R.; Basavanneppa, M. A.; Udikeri, S. S.

    2012-04-01

    Field experiments were conducted over three rainy seasons of 2005-06 to 2007-08 on a Vertisol at Dharwad, Karnataka, India to study the effect of intercropping and plant protection schedules on productivity, soil microflora and enzyme activities in the rhizosphere of transgenic Bt cotton hybrid. The experiment consisted of four intercropping systems namely, Bt cotton + okra, Bt cotton + chilli, Bt cotton + onion + chilli and Bt cotton + redgram with four plant protection schedules (zero protection, protection for Bt cotton, protection for intercrop and protection for both crops). Observations on microbial populations and enzyme activities were recorded at 45, 90, 135 and 185 (at harvest) days after sowing (DAS). Averaged over years, Bt cotton + okra intercropping had significantly higher total productivity than Bt cotton + chilli and Bt cotton + redgram intercropping system and was similar to Bt cotton + chilli + onion intercropping system. With respect to plant protection schedules for bollworms, protection for both cotton and intercrops recorded significantly higher yield than the rest of the treatments. Population of total bacteria, fungi, actinomycetes, P-solubilizers, free-living N2 fixers as well as urease, phosphatase and dehydrogenase enzyme activities increased up to 135 days of crop growth followed by a decline. Among the intercropping systems, Bt cotton + chilli recorded significantly higher population of microorganisms and enzyme activities than other cropping systems. While Bt cotton with okra as intercrop recorded the least population of total bacteria and free-living N2 fixers as well as urease activity. Intercropping with redgram resulted in the least population of actinomycetes, fungi and P-solubilizers, whereas Bt cotton with chilli and onion recorded least activities of dehydrogenase and phosphatase. Among the plant protection schedules, zero protection recorded maximum population of microorganisms and enzyme activities. This was followed by the

  1. Herbivore-specific, density-dependent induction of plant volatiles: honest or "cry wolf" signals?

    Directory of Open Access Journals (Sweden)

    Kaori Shiojiri

    Full Text Available Plants release volatile chemicals upon attack by herbivorous arthropods. They do so commonly in a dose-dependent manner: the more herbivores, the more volatiles released. The volatiles attract predatory arthropods and the amount determines the probability of predator response. We show that seedlings of a cabbage variety (Brassica oleracea var. capitata, cv Shikidori also show such a response to the density of cabbage white (Pieris rapae larvae and attract more (naive parasitoids (Cotesia glomerata when there are more herbivores on the plant. However, when attacked by diamondback moth (Plutella xylostella larvae, seedlings of the same variety (cv Shikidori release volatiles, the total amount of which is high and constant and thus independent of caterpillar density, and naive parasitoids (Cotesia vestalis of diamondback moth larvae fail to discriminate herbivore-rich from herbivore-poor plants. In contrast, seedlings of another cabbage variety of B. oleracea (var. acephala: kale respond in a dose-dependent manner to the density of diamondback moth larvae and attract more parasitoids when there are more herbivores. Assuming these responses of the cabbage cultivars reflect behaviour of at least some genotypes of wild plants, we provide arguments why the behaviour of kale (B. oleracea var acephala is best interpreted as an honest signaling strategy and that of cabbage cv Shikidori (B. oleracea var capitata as a "cry wolf" signaling strategy, implying a conflict of interest between the plant and the enemies of its herbivores: the plant profits from being visited by the herbivore's enemies, but the latter would be better off by visiting other plants with more herbivores. If so, evolutionary theory on alarm signaling predicts consequences of major interest to students of plant protection, tritrophic systems and communication alike.

  2. Describing a multitrophic plant-herbivore-parasitoid system at four spatial scales

    Science.gov (United States)

    Cuautle, M.; Parra-Tabla, V.

    2014-02-01

    Herbivore-parasitoid interactions must be studied using a multitrophic and multispecies approach. The strength and direction of multiple effects through trophic levels may change across spatial scales. In this work, we use the herbaceous plant Ruellia nudiflora, its moth herbivore Tripudia quadrifera, and several parasitoid morphospecies that feed on the herbivore to answer the following questions: Do herbivore and parasitoid attack levels vary depending on the spatial scale considered? With which plant characteristics are the parasitoid and the herbivore associated? Do parasitoid morphospecies vary in the magnitude of their positive indirect effect on plant reproduction? We evaluated three approximations of herbivore and parasitoid abundance (raw numbers, ratios, and attack rates) at four spatial scales: regional (three different regions which differ in terms of abiotic and biotic characteristics); population (i.e. four populations within each region); patch (four 1 m2 plots in each population); and plant level (using a number of plant characteristics). Finally, we determined whether parasitoids have a positive indirect effect on plant reproductive success (seed number). Herbivore and parasitoid numbers differed at three of the spatial scales considered. However, herbivore/fruit ratio and attack rates did not differ at the population level. Parasitoid/host ratio and attack rates did not differ at any scale, although there was a tendency of a higher attack in one region. At the plant level, herbivore and parasitoid abundances were related to different plant traits, varying the importance and the direction (positive or negative) of those traits. In addition, only one parasitoid species (Bracon sp.) had a positive effect on plant fitness saving up to 20% of the seeds in a fruit. These results underline the importance of knowing the scales that are relevant to organisms at different trophic levels and distinguish between the specific effects of species.

  3. Larval development of Spodoptera eridania (Cramer) fed on leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 proteins and its non-Bt isoline

    OpenAIRE

    2015-01-01

    This study aimed to evaluate, in controlled laboratory conditions (temperature of 25±2 °C, relative humidity of 60±10%, and 14/10 h L/D photoperiod), the larval development of Spodoptera eridania (Cramer, 1784) (Lepidoptera, Noctuidae) fed with leaves of Bt maize expressing Cry1F and Cry1F + Cry1A.105 + Cry2Ab2 insecticide proteins and its non-Bt isoline. Maize leaves triggered 100% of mortality on S. eridania larvae independently of being Bt or non-Bt plants. However, it was observed that in...

  4. Test Review: Test of English as a Foreign Language[TM]--Internet-Based Test (TOEFL iBT[R])

    Science.gov (United States)

    Alderson, J. Charles

    2009-01-01

    In this article, the author reviews the TOEFL iBT which is the latest version of the TOEFL, whose history stretches back to 1961. The TOEFL iBT was introduced in the USA, Canada, France, Germany and Italy in late 2005. Currently the TOEFL test is offered in two testing formats: (1) Internet-based testing (iBT); and (2) paper-based testing (PBT).…

  5. Chloroplast-targeted expression of recombinant crystal-protein gene in cotton: an unconventional combat with resistant pests.

    Science.gov (United States)

    Kiani, Sarfraz; Mohamed, Bahaeldeen Babiker; Shehzad, Kamran; Jamal, Adil; Shahid, Muhammad Naveed; Shahid, Ahmad Ali; Husnain, Tayyab

    2013-07-10

    Plants transformed with single Bt gene are liable to develop insect resistance and this has already been reported in a number of studies carried out around the world where Bt cotton was cultivated on commercial scale. Later, it was envisaged to transform plants with more than one Bt genes in order to combat with resistant larvae. This approach seems valid as various Bt genes possess different binding domains which could delay the likely hazards of insect resistance against a particular Bt toxin. But it is difficult under field conditions to develop homozygous plants expressing all Bt genes equally after many generations without undergoing recombination effects. A number of researches claiming to transform plants from three to seven transgenes in a single plant were reported during the last decade but none has yet applied for patent of homozygous transgenic lines. A better strategy might be to use hybrid-Bt gene(s) modified for improved lectin-binding domains to boost Bt receptor sites in insect midgut. These recombinant-Bt gene(s) would express different lectin domains in a single polypeptide and it is relatively easy to develop homozygous transgenic lines under field conditions. Enhanced chloroplast-localized expression of hybrid-Bt gene would leave no room for insects to develop resistance. We devised and successfully applied this strategy in cotton (Gossypium hirsutum) and data up to T3 generation showed that our transgenic cotton plants were displaying enhanced chloroplast-targeted Cry1Ac-RB expression. Laboratory and field bioassays gave promising results against American bollworm (Heliothis armigera), pink bollworm (Pictinophora scutigera) and fall armyworm (Spodoptera frugiperda) that otherwise, were reported to have evolved resistance against Cry1Ac toxin. Elevated levels of hybrid-Bt toxin were confirmed by ELISA of chloroplast-enriched protein samples extracted from leaves of transgenic cotton lines. While, localization of recombinant Cry1Ac-RB protein in

  6. Persistence of Bt Bacillus thuringiensis Cry1Aa toxin in various soils determined by physicochemical reactions

    Science.gov (United States)

    Helassa, N.; Noinville, S.; Déjardin, P.; Janot, J. M.; Quiquampoix, H.; Staunton, S.

    2009-04-01

    Insecticidal Cry proteins from the soil bacterium, Bacillus thuringiensis (Bt) are produced by a class of genetically modified (GM) crops, and released into soils through root exudates and upon decomposition of residues. In contrast to the protoxin produced by the Bacillus, the protein produced in GM crops does not require activation in insect midguts and thereby potentially looses some of its species specificity. Although gene transfer and resistance emergence phenomena are well documented, the fate of these toxins in soil has not yet been clearly elucidated. Cry proteins, in common with other proteins, are adsorbed on soils and soil components. Adsorption on soil, and the reversibility of this adsorption is an important aspect of the environmental behaviour of these toxins. The orientation of the molecule and conformational changes on surfaces may modify the toxicity and confer some protection against microbial degradation. Adsorption will have important consequences for both the risk of exposition of non target species and the acquisition of resistance by target species. We have adopted different approaches to investigate the fate of Cry1Aa in soils and model minerals. In each series of experiments we endeavoured to maintain the protein in a monomeric form (pH above 6.5 and a high ionic strength imposed with 150 mM NaCl). The adsorption and the desorbability of the Cry1Aa Bt insecticidal protein were measured on two different homoionic clays: montmorillonite and kaolinite. Adsorption isotherms obtained followed a low affinity interaction for both clays and could be fitted using the Langmuir equation. Binding of the toxin decreased as the pH increased from 6.5 (close to the isoelectric point) to 9. Maximum adsorption was about 40 times greater on montmorillonite (1.71 g g-1) than on kaolinite (0.04 g g-1) in line with the contrasting respective specific surface areas of the minerals. Finally, some of the adsorbed toxin was desorbed by water and more, about 36

  7. Overexpression of a Foreign Bt Gene in Cotton Affects the Low-Molecular-Weight Components in Root Exudates

    Institute of Scientific and Technical Information of China (English)

    YAN Wei-Dong; SHI Wei-Ming; LI Bao-Hai; ZHANG Min

    2007-01-01

    Most research in the past using genetically modified crops (GM crops) has focused on the ecological safety of foreign gene (i.e., the gene flow), gene products (for example, Bt (Bacillus thuringiensis) protein), and the safety of transgenic food for humans. In this study, changes in both the species and amounts of low-molecular-weight components in cotton (Gossypium hirsutum L.) root exudates after foreign Bt gene overexpression were investigated under different nutritional conditions. Transgenic cotton containing Bt (Bt-cotton), supplemented with all the mineral nutrients, secreted more organic acids than the wild-type cotton (WT). When nitrogen was removed from the full-nutrient solution, the amount of organic acids secretion of Bt-cotton was lesser than that of WT. The roots of the transgenic cotton secreted lesser amounts of amino acids and soluble sugars than the WT roots in the full-nutrient solution. Deficiencies of P and K caused a large increase in the total amino acid and soluble sugar secretions of both Bt-cotton and WT, with larger increases observed in Bt-cotton. Because transferring the foreign Bt gene into cotton can result in alterations in the components of the root exudates, with the effect varying depending on the nutritional status, the cultivation of genetically modified crops, such as Bt-cotton, in soil environments should be more carefully assessed, and the possible effects as a result of the alterations in the root exudate components should be considered.

  8. Matching the BtA line to the bare-AGS (Part 1)

    Energy Technology Data Exchange (ETDEWEB)

    Tsoupas,N.; Glenn, J. W.; Huan, H.; MacKay, W. W.; Raparia, D.; Zeno, K.

    2008-11-01

    The Booster to AGS (BtA) transfer line [Ref for BtA line] transports the beam bunches from the AGS-Booster to the AGS synchrotron, and also matches the beam parameters ({beta}{sub x,y}, {alpha}{sub x,y}) and dispersion functions ({eta}{sub x,y}, {eta}{prime}{sub x,y}) of the transported beam to the corresponding quantities of the circulating beam in AGS, at the AGS injection point. In this technical note we describe in details, the calculations of the matching procedure of the BtA line to the bare-AGS, and provide magnet settings for the MAD-model of the BtA transfer line which is 'matched' to the bare-AGS. In a separate but more concise technical note (Part II) we will present results on the beam optics of the BtA beam line which is 'matched' to the AGS with two helical snakes.

  9. Effect of irradiation on physiological and biochemical properties of Bt rice seedlings

    International Nuclear Information System (INIS)

    The seeds of two varieties of Bt rice were treated by 60Co γ-rays at the doses of 50, 100, 150, 250 and 350 Gy, respectively, their original parent was used as control material. The seedlings cultured from above seeds were used to detect the root activity, seedling growth, chlorophyll content,activities of phenylalanine ammonialyase (PAL), polyphenol oxidase (PPO), catalase(CAT), superoxide dismutase (SOD) and amylase to investigate the effect of irradiation treatment on the physiological and biochemical properties of Bt rice. The results showed that root activity, chlorophyll content, activities of PAL, PPO, CAT, SOD of Bt rice seedlings and amylase of germinating seeds were lower than those of the control group after irradiation treatment of < 250 Gy, but the differences were not significant, which was similar to those of original parent. Meanwhile, it was found that with dose increasing, the seedling height was increased, suggesting that irradiation treatment could stimulate the seedling growth. Therefore, Bt transgene can not change the irradiation sensitivity of rice and the conventional method of rice can be used in Bt rice irradiation mutation breeding. (authors)

  10. Cellular penetration and nuclear importation properties of 111In-labeled and 123I-labeled HIV-1 tat peptide immunoconjugates in BT-474 human breast cancer cells

    International Nuclear Information System (INIS)

    Introduction: Our objective was to compare the cell penetration and nuclear importation properties of 111In-labeled and 123I-labeled immunoconjugates (ICs) composed of 16-mer peptides (GRKKRRQRRRPPQGYG) derived from HIV-1 transactivator of transcription (tat) protein and anti-mouse IgG (mIgG) in BT-474 breast cancer (BC) cells. Methods: [111In]tat ICs were constructed by site-specific conjugation of tat peptides to NaIO4--oxidized carbohydrates in the Fc domain of diethylenetriaminepentaacetic-acid-modified anti-mIgG antibodies. Immunoreactivity against mIgG was assessed in a competition assay. The kinetics of the accumulation of [111In]anti-mIgG-tat IC and [123I]anti-mIgG-tat ICs in BT-474 cells and the elimination of radioactivity from cells, cytoplasm or nuclei were determined. The effects of excess tat peptides or NH4Cl (an inhibitor of endosomal acidification) on cellular uptake and nuclear importation of [111In]anti-mIgG-tat were measured. Results: [111In]anti-mIgG-tat was >97% radiochemically pure and exhibited preserved immunoreactivity with mIgG epitopes. [123I]Anti-mIgG-tat penetrated BT-474 cells more rapidly than [111In]anti-mIgG-tat ICs and achieved a 1.5-fold to a 2-fold higher uptake in cells and nuclei. Cell penetration and nuclear uptake of [111In]anti-mIgG-tat were inhibited by excess tat peptides and NH4Cl. Elimination of radioactivity from BT-474 cells and nuclei was more rapid and complete for 123I-labeled than for 111In-labeled anti-mIgG-tat ICs. Conclusion: Tat peptides derived from HIV-1 tat protein promoted the penetration and nuclear uptake of radioactivity following the incubation of 111In-labeled and 123I-labeled anti-mIgG antibodies with BT-474 human BC cells. 111In-labeled tat ICs are feasible for inserting radionuclides into cancer cells with potential for targeting intracellular and, particularly, nuclear epitopes for imaging and/or radiotherapeutic applications

  11. Evaluation of anti-HER2 scFv-conjugated PLGA-PEG nanoparticles on 3D tumor spheroids of BT474 and HCT116 cancer cells

    Science.gov (United States)

    Thuy Duong Le, Thi; Pham, Thu Hong; Nghia Nguyen, Trong; Giang Ngo, Thi Hong; Nhung Hoang, Thi My; Huan Le, Quang

    2016-06-01

    Three-dimensional culture cells (spheroids) are one of the multicellular culture models that can be applied to anticancer chemotherapeutic development. Multicellular spheroids more closely mimic in vivo tumor-like patterns of physiologic environment and morphology. In previous research, we designed docetaxel-loaded pegylated poly(D, L-lactide-co-glycolide) nanoparticles conjugated with anti-HER2 single chain antibodies (scFv-Doc-PLGA-PEG) and evaluated them in 2D cell culture. In this study, we continuously evaluate the cellular uptake and cytotoxic effect of scFv-Doc-PLGA-PEG on a 3D tumor spheroid model of BT474 (HER2-overexpressing) and HCT116 (HER2-underexpressing) cancer cells. The results showed that the nanoparticle formulation conjugated with scFv had a significant internalization effect on the spheroids of HER2-overexpressing cancer cells as compared to the spheroids of HER2-underexpressing cancer cells. Therefore, cytotoxic effects of targeted nanoparticles decreased the size and increased necrotic score of HER2-overexpressing tumor spheroids. Thus, these scFv-Doc-PLGA-PEG nanoparticles have potential for active targeting for HER2-overexpressing cancer therapy. In addition, BT474 and HCT116 spheroids can be used as a tumor model for evaluation of targeting therapies.

  12. A Global Analysis of the Relationship between Farmed Seaweed Production and Herbivorous Fish Catch.

    Science.gov (United States)

    Hehre, E James; Meeuwig, Jessica J

    2016-01-01

    Globally, farmed seaweed production is expanding rapidly in shallow marine habitats. While seaweed farming provides vital income to millions of artisanal farmers, it can negatively impact shallow coral reef and seagrass habitats. However, seaweed farming may also potentially provide food subsidies for herbivorous reef fish such as the Siganidae, a valuable target family, resulting in increased catch. Comparisons of reef fish landings across the central Philippines revealed that the catch of siganids was positively correlated to farmed seaweed production whilst negatively correlated to total reef fish catch over the same period of time. We tested the generality of this pattern by analysing seaweed production, siganid catch, and reef fish catch for six major seaweed-producing countries in the tropics. We hypothesized that increased seaweed production would correspond with increased catch of siganids but not other reef fish species. Analysis of the global data showed a positive correlation between farmed seaweeds and siganids in Southeast Asia (Indonesia, Malaysia, and the Philippines) but not Africa (Tanzania and Zanzibar), or the Western Pacific (Fiji). In Southeast Asia, siganid catch increased disproportionately faster with seaweed production than did reef fish catch. Low continuity, sporadic production and smaller volumes of seaweed farming may explain the differences. PMID:26894553

  13. A Global Analysis of the Relationship between Farmed Seaweed Production and Herbivorous Fish Catch.

    Directory of Open Access Journals (Sweden)

    E James Hehre

    Full Text Available Globally, farmed seaweed production is expanding rapidly in shallow marine habitats. While seaweed farming provides vital income to millions of artisanal farmers, it can negatively impact shallow coral reef and seagrass habitats. However, seaweed farming may also potentially provide food subsidies for herbivorous reef fish such as the Siganidae, a valuable target family, resulting in increased catch. Comparisons of reef fish landings across the central Philippines revealed that the catch of siganids was positively correlated to farmed seaweed production whilst negatively correlated to total reef fish catch over the same period of time. We tested the generality of this pattern by analysing seaweed production, siganid catch, and reef fish catch for six major seaweed-producing countries in the tropics. We hypothesized that increased seaweed production would correspond with increased catch of siganids but not other reef fish species. Analysis of the global data showed a positive correlation between farmed seaweeds and siganids in Southeast Asia (Indonesia, Malaysia, and the Philippines but not Africa (Tanzania and Zanzibar, or the Western Pacific (Fiji. In Southeast Asia, siganid catch increased disproportionately faster with seaweed production than did reef fish catch. Low continuity, sporadic production and smaller volumes of seaweed farming may explain the differences.

  14. The presence of root-feeding nematodes - Not AMF - Affects an herbivore dispersal strategy

    Science.gov (United States)

    De Roissart, Annelies; Peña, Eduardo de la; Van Oyen, Lien; Van Leeuwen, Thomas; Ballhorn, Daniel J.; Bonte, Dries

    2013-10-01

    Plant quality and aboveground herbivore performance are influenced either directly or indirectly by the soil community. As herbivore dispersal is a conditional strategy relative to plant quality, we examined whether belowground biotic interactions (the presence of root-feeding nematodes or arbuscular mycorrhizal fungi) affect aerial dispersal of a phytophagous mite (Tetranychus urticae) through changes in performance of their host plant (Phaseolus vulgaris). Aerial dispersal strategies of mites were analyzed in wind-tunnel experiments, in which a unique mite pre-dispersal behavior (rearing) was assessed in relation to the presence of belowground biota on the host plant on which mites developed. Spider mite pre-dispersal behavior significantly increased with the experienced mite density on the host during development. Additionally, plants infected with root-feeding nematodes induced an increase of spider mite aerial dispersal behavior. The results highlight that belowground herbivores can affect population dynamics of aboveground herbivores by altering dispersal strategies.

  15. Linking traits between plants and invertebrate herbivores to track functional effects of land-use changes

    Czech Academy of Sciences Publication Activity Database

    Moretti, M.; de Bello, Francesco; Ibanez, S.; Fontana, S.; Pezzatti, G. B.; Dziock, F.; Rixen, Ch.; Lavorel, S.

    2013-01-01

    Roč. 24, č. 5 (2013), s. 949-962. ISSN 1100-9233 Institutional support: RVO:67985939 Keywords : Functional dissimilarity * Herbivory * Plant–herbivore interaction Subject RIV: EH - Ecology, Behaviour Impact factor: 3.372, year: 2013

  16. Forage patch use by grazing herbivores in a South African grazing ecosystem

    NARCIS (Netherlands)

    Venter, J.A.; Nabe-Nielsen, J.; Prins, H.H.T.; Slotow, R.

    2014-01-01

    Understanding how different herbivores make forage patch use choices explains how they maintain an adequate nutritional status, which is important for effective conservation management of grazing ecosystems. Using telemetry data, we investigated nonruminant zebra (Equus burchelli) and ruminant red h

  17. Monitoring large herbivore diversity at different scales : comparing direct and indirect methods

    NARCIS (Netherlands)

    Cromsigt, Joris P. G. M.; van Rensburg, Susan J.; Etienne, Rampal S.; Olff, Han

    2009-01-01

    Monitoring of large herbivores is central to research and management activities in many protected areas. Monitoring programs were originally developed to estimate (trends in) population sizes of individual species. However, emphasis is shifting increasingly towards conservation of diversity and comm

  18. Monitoring large herbivore diversity at different scales: comparing direct and indirect methods

    NARCIS (Netherlands)

    Cromsigt, J.P.G.M.; Rensburg, S.J.; Etienne, R.S.; Olff, H.

    2009-01-01

    Monitoring of large herbivores is central to research and management activities in many protected areas. Monitoring programs were originally developed to estimate (trends in) population sizes of individual species. However, emphasis is shifting increasingly towards conservation of diversity and comm

  19. The effects of large herbivores on the landscape dynamics of a perennial herb

    Czech Academy of Sciences Publication Activity Database

    Hemrová, Lucie; Červenková, Z.; Münzbergová, Zuzana

    2012-01-01

    Roč. 110, č. 7 (2012), s. 1411-1421. ISSN 0305-7364 Institutional support: RVO:67985939 Keywords : herbivores * Scorzonera hispanica * landscape Subject RIV: EF - Botanics Impact factor: 3.449, year: 2012

  20. DEGRADATION OF Bt PROTEIN IN GROUND LEAVES AND BUDS FROM TRANSGENIC Bt COTTON%转Bt基因棉粉碎叶、蕾样Bt蛋白降解

    Institute of Scientific and Technical Information of China (English)

    张美俊; 杨武德

    2011-01-01

    以转Bt基因棉Bt冀668为材料,室内采用ELISA法,测定粉碎叶、蕾样Bt蛋白在土壤、水中不同时间的残留量以及不同环境处理下的残留量,以研究转Bt基因棉粉碎叶、蕾样Bt蛋白在不同基质中的降解动态以及与环境影响因子的关系.结果显示,粉碎叶、蕾样Bt蛋白分别在熟土、生土和水中前40d、48d取样天数间的残留量差异显著,中后期相邻两取样间无显著差异.取样结束时,熟土、生土和水中粉碎叶Bt蛋白残留量分别为初始量的7.4%、2.24%和15.48%,蕾样为初始量的6.22%、4.72%和15.71%,表明Bt蛋白在熟土、生土和水中前期快速降解,中后期进入缓慢稳定降解阶段,水中降解速率最慢,熟土中前期降解快于生土,后期降解反而慢于生土,使得其取样结束时残留量高于生土.75%含水量土壤中,粉碎叶Bt蛋白的降解显著快于25%和50%处理;35℃和25℃下降解显著快于15℃,5℃降解最慢;在有茵土中Bt蛋白的降解显著快于无菌土.上述结果显示一定范围内,高温、高湿可加快Bt蛋白的降解,且土壤微生物是促进Bt蛋白降解的重要因子之一.%The degradation dynamics of Bt protein in ground leaves and buds from transgenic Bt cotton in different substrates and their relation with environmental factors were investigated. Ground powers of BtJi 668 leaves and buds were mixed with soil or water, and residue Bt protein contents during sampling days (0 ~ 88days) and under different environment were determined by using enzyme-linked immunosorbent essay (ELISA) in laboratory. Residue Bt protein contents in ground leaves and buds had significant difference among sampling days at early stages, however, no difference between adjoining sampling days at middle and later stages in three substrates ripened soil, unripened soil and water. At the end of treated time, residue Bt protein contents in ground leaves decreased to 7.4% ,2. 24% and 15.48%, and in buds to

  1. Do native herbivores provide resistance to Mediterranean marine bioinvasions? A seaweed example

    OpenAIRE

    Cebrián Pujol, Emma; Ballesteros i Segarra, Enric; Linares, Cristina; Tomás, Fiona

    2011-01-01

    Generalist herbivores in marine ecosystems are poorly examined for their potential to serve as a source of biotic resistance against algal invasion. We assessed how one of the main generalist herbivores in Mediterranean rocky reefs (the sea urchin Paracentrotus lividus) affects Lophocladia lallemandii and Caulerpa racemosa, two algal invaders with strong detrimental effects on native benthic communities. In a comparison of sea urchin gut contents to algal community composition, strong prefere...

  2. Indole is an essential herbivore-induced volatile priming signal in maize

    OpenAIRE

    Erb, Matthias; Veyrat, Nathalie; Robert, Christelle A. M.; Xu, Hao; Frey, Monika; Ton, Jurriaan; Turlings, Ted C. J.

    2015-01-01

    Herbivore-induced volatile organic compounds prime non-attacked plant tissues to respond more strongly to subsequent attacks. However, the key volatiles that trigger this primed state remain largely unidentified. In maize, the release of the aromatic compound indole is herbivore-specific and occurs earlier than other induced responses. We therefore hypothesized that indole may be involved in airborne priming. Using indole-deficient mutants and synthetic indole dispensers, we show that herbivo...

  3. Phytochemical mimicry of reproductive hormones and modulation of herbivore fertility by phytoestrogens.

    OpenAIRE

    Hughes, C. L.

    1988-01-01

    Plants have physical and chemical mechanisms for defense from attack by animals. Phytochemical defenses that protect plants from attack by insects include antifeedants, insecticides, and insect growth regulators. Phytochemical options exist by which plants can modulate the fertility of the other major group of plant predators, vertebrate herbivores, and thereby reduce cumulative attacks by those herbivores. The success of such a defense depends upon phytochemical mimicry of vertebrate reprodu...

  4. The rapidly evolving associations among herbivore associated elicitor-induced phytohormones in Nicotiana

    OpenAIRE

    Xu, Shuqing; Zhou, Wenwu; Baldwin, Ian T

    2015-01-01

    In response to herbivore attack, plants perceive herbivore associated elicitors (HAE) and rapidly accumulate jasmonic acid (JA) and other phytohormones, which interact in complex ways, such as the crosstalk between JA and salicylic acid (SA). Although recent studies have shown that HAE-induced individual phytohormones can be highly specific among closely related species, it remains unclear how conserved and specific the relationships among HAE-induced phytohormones are. Here we analyzed the c...

  5. Plant quantity affects development and survival of a gregarious insect herbivore and its endoparasitoid wasp.

    OpenAIRE

    Minghui Fei; Rieta Gols; Feng Zhu; Harvey, Jeffrey A.

    2016-01-01

    Virtually all studies of plant-herbivore-natural enemy interactions focus on plant quality as the major constraint on development and survival. However, for many gregarious feeding insect herbivores that feed on small or ephemeral plants, the quantity of resources is much more limiting, yet this area has received virtually no attention. Here, in both lab and semifield experiments using tents containing variably sized clusters of food plants, we studied the effects of periodic food deprivation...

  6. Herbivore-specific, density-dependent induction of plant volatiles: Honest or "cry wolf" signals?

    OpenAIRE

    Kaori Shiojiri; Rika Ozawa; Soichi Kugimiya; Masayoshi Uefune; Michiel van Wijk; Sabelis, Maurice W.; Junji Takabayashi

    2010-01-01

    Plants release volatile chemicals upon attack by herbivorous arthropods. They do so commonly in a dose-dependent manner: the more herbivores, the more volatiles released. The volatiles attract predatory arthropods and the amount determines the probability of predator response. We show that seedlings of a cabbage variety (Brassica oleracea var. capitata, cv Shikidori) also show such a response to the density of cabbage white (Pieris rapae) larvae and attract more (naive) parasitoids (Cotesia g...

  7. Giant lizards occupied herbivorous mammalian ecospace during the Paleogene greenhouse in Southeast Asia

    OpenAIRE

    Head, Jason J.; Gunnell, Gregg F.; Holroyd, Patricia A.; Hutchison, J. Howard; Ciochon, Russell L.

    2013-01-01

    Mammals dominate modern terrestrial herbivore ecosystems, whereas extant herbivorous reptiles are limited in diversity and body size. The evolution of reptile herbivory and its relationship to mammalian diversification is poorly understood with respect to climate and the roles of predation pressure and competition for food resources. Here, we describe a giant fossil acrodontan lizard recovered with a diverse mammal assemblage from the late middle Eocene Pondaung Formation of Myanmar, which pr...

  8. Among rodents and rhinos: interplay between small mammals and large herbivores in a South African savanna

    OpenAIRE

    Hagenah, N.

    2006-01-01

    Keywords:African savanna, biodiversity, Dichrostachys cinerea , different-sized herbivores, fire, herbivore interactions, murid rodents, spatial heterogeneityMankind has caused species extinction of many groups of organisms through the transformation and fragmentation of once continuous natural habitats. In order to protect and restore natural biodiversity hotspots such as the African savannas we need to understand the determinants of their community structure and species diversity. Evidence ...

  9. The key to success: host plant adaptations in the root herbivore 'Diabrotica virgifera virgifera'

    OpenAIRE

    Robert, Christelle A.M; Turlings, Ted C.

    2012-01-01

    Antagonistic interactions between plants and insects are likely the drivers of a fascinating coevolutionary arms race between the two trophic levels. Plants- and plant breeders- are continuously developing traits that allow them to fend-off herbivores, while phytophagous insect keep inventing counter-adaptations to withstand plant defenses. Diabrotica virgifera virgifera LeConte (Coleoptera: Chrysomelidae) is a specialist root herbivore of maize, Zea mays. Known as the billion dollar bug in ...

  10. Herbivore-initiated interaction cascades and their modulation by productivity in an African savanna

    OpenAIRE

    Pringle, Robert M.; Young, Truman P; Rubenstein, Daniel I.; McCauley, Douglas J.

    2006-01-01

    Despite conceptual recognition that indirect effects initiated by large herbivores are likely to have profound impacts on ecological community structure and function, the existing literature on indirect effects focuses largely on the role of predators. As a result, we know neither the frequency and extent of herbivore-initiated indirect effects nor the mechanisms that regulate their strength. We examined the effects of ungulates on taxa (plants, arthropods, and an insectivorous lizard) repres...

  11. Intra- and interspecific differences in diet quality and composition in a large herbivore community.

    Science.gov (United States)

    Redjadj, Claire; Darmon, Gaëlle; Maillard, Daniel; Chevrier, Thierry; Bastianelli, Denis; Verheyden, Hélène; Loison, Anne; Saïd, Sonia

    2014-01-01

    Species diversity in large herbivore communities is often explained by niche segregation allowed by differences in body mass and digestive morphophysiological features. Based on large number of gut samples in fall and winter, we analysed the temporal dynamics of diet composition, quality and interspecific overlap of 4 coexisting mountain herbivores. We tested whether the relative consumption of grass and browse differed among species of different rumen types (moose-type and intermediate-type), whether diet was of lower quality for the largest species, whether we could identify plant species which determined diet quality, and whether these plants, which could be "key-food-resources" were similar for all herbivores. Our analyses revealed that (1) body mass and rumen types were overall poor predictors of diet composition and quality, although the roe deer, a species with a moose-type rumen was confirmed as an "obligatory non grazer", while red deer, the largest species, had the most lignified diet; (2) diet overlap among herbivores was well predicted by rumen type (high among species of intermediate types only), when measured over broad plant groups, (3) the relationship between diet composition and quality differed among herbivore species, and the actual plant species used during winter which determined the diet quality, was herbivore species-specific. Even if diets overlapped to a great extent, the species-specific relationships between diet composition and quality suggest that herbivores may select different plant species within similar plant group types, or different plant parts and that this, along with other behavioural mechanisms of ecological niche segregation, may contribute to the coexistence of large herbivores of relatively similar body mass, as observed in mountain ecosystems. PMID:24586233

  12. Intra- and interspecific differences in diet quality and composition in a large herbivore community.

    Directory of Open Access Journals (Sweden)

    Claire Redjadj

    Full Text Available Species diversity in large herbivore communities is often explained by niche segregation allowed by differences in body mass and digestive morphophysiological features. Based on large number of gut samples in fall and winter, we analysed the temporal dynamics of diet composition, quality and interspecific overlap of 4 coexisting mountain herbivores. We tested whether the relative consumption of grass and browse differed among species of different rumen types (moose-type and intermediate-type, whether diet was of lower quality for the largest species, whether we could identify plant species which determined diet quality, and whether these plants, which could be "key-food-resources" were similar for all herbivores. Our analyses revealed that (1 body mass and rumen types were overall poor predictors of diet composition and quality, although the roe deer, a species with a moose-type rumen was confirmed as an "obligatory non grazer", while red deer, the largest species, had the most lignified diet; (2 diet overlap among herbivores was well predicted by rumen type (high among species of intermediate types only, when measured over broad plant groups, (3 the relationship between diet composition and quality differed among herbivore species, and the actual plant species used during winter which determined the diet quality, was herbivore species-specific. Even if diets overlapped to a great extent, the species-specific relationships between diet composition and quality suggest that herbivores may select different plant species within similar plant group types, or different plant parts and that this, along with other behavioural mechanisms of ecological niche segregation, may contribute to the coexistence of large herbivores of relatively similar body mass, as observed in mountain ecosystems.

  13. Insect attraction to herbivore-induced beech volatiles under different forest management regimes.

    Science.gov (United States)

    Gossner, Martin M; Weisser, Wolfgang W; Gershenzon, Jonathan; Unsicker, Sybille B

    2014-10-01

    Insect herbivore enemies such as parasitoids and predators are important in controlling herbivore pests. From agricultural systems we know that land-use intensification can negatively impact biological control as an important ecosystem service. The aim of our study was to investigate the importance of management regime for natural enemy pressure and biological control possibilities in forests dominated by European beech. We hypothesize that the volatile blend released from herbivore-infested beech trees functions as a signal, attracting parasitoids and herbivore enemies. Furthermore, we hypothesize that forest management regime influences the composition of species attracted by these herbivore-induced beech volatiles. We installed flight-interception traps next to Lymantria dispar caterpillar-infested young beech trees releasing herbivore-induced volatiles and next to non-infested control trees. Significantly more parasitoids were captured next to caterpillar-infested trees compared to non-infested controls, irrespective of forest type. However, the composition of the trophic guilds in the traps did vary in response to forest management regime. While the proportion of chewing insects was highest in non-managed forests, the proportion of sucking insects peaked in forests with low management and of parasitoids in young, highly managed, forest stands. Neither the number of naturally occurring beech saplings nor herbivory levels in the proximity of our experiment affected the abundance and diversity of parasitoids caught. Our data show that herbivore-induced beech volatiles attract herbivore enemies under field conditions. They further suggest that differences in the structural complexity of forests as a consequence of management regime only play a minor role in parasitoid activity and thus in indirect tree defense. PMID:25080178

  14. Evidence for functional convergence in genes upregulated by herbivores ingesting plant secondary compounds

    OpenAIRE

    Jael R Malenke; Skopec, Michele M.; Dearing, M. Denise

    2014-01-01

    Background Nearly 40 years ago, Freeland and Janzen predicted that liver biotransformation enzymes dictated diet selection by herbivores. Despite decades of research on model species and humans, little is known about the biotransformation mechanisms used by mammalian herbivores to metabolize plant secondary compounds (PSCs). We investigated the independent evolution of PSC biotransformation mechanisms by capitalizing on a dramatic diet change event—the dietary inclusion of creosote bush (Larr...

  15. Bt Cotton in China: Are Secondary Insect Infestations Offsetting the Benefits in Farmer Fields?

    Institute of Scientific and Technical Information of China (English)

    WANG Zi-jun; LIN Hai; HUANG Ji-kun; HU Rui-fa; Scott Rozelle; Carl Pray

    2009-01-01

    The area sown to Bt cotton has expanded rapidly in China since 1997. It has effectively controlled the bollworm. However, in recent years, concern has surfaced about the emergence of secondary insect pests, particular mirids, in Bt cotton fields. This study measures the patterns of insecticide use based on farm-level from 1999 to 2006, the analysis demonstrates a rise in insecticide use to control mirids between 2001 and 2004, secondary insect infestations is largely related to the rise of mirids, but this rising did not continue in more than half of sample villages studied in 2004-2006. Moreover, the increase in insecticide use for the control of secondary insects is far smaller than the reduction in total insecticide use due to Bt cotton adoption. Further econometric analyses show that rise and fall of mirids is largely related to local temperature and rainfall.

  16. Effect of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    Temperature is one of the key parameters for BT20 titanium alloy cylindrical workpiece manufactured by vacuum hot bulge forming. A two-dimensional nonlinear thermo-mechanical coupled FE model was established. Numerical simulation of vacuum hot bulge forming process of titanium alloy cylindrical workpiece was carried out using FE analysis software MSC Marc. The effects of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece were analyzed by numerical simulation.The simulated results show that the Y-direction displacement and the equivalent plastic strain of the workpiece increase with increasing bulge temperature. The residual stress decreases with increasing bulge temperature. The optimal temperature range of BT20 titanium alloy during vacuum hot bulge forming is 750-850 ℃. The corresponding experiments were carried out. The simulated results agreed well with the experimental results.

  17. Contrasting impacts of different-sized herbivores on species richness of Mediterranean annual pastures differing in primary productivity.

    Science.gov (United States)

    Rueda, Marta; Rebollo, Salvador; García-Salgado, Gonzalo

    2013-06-01

    Vertebrate herbivores can be key determinants of grassland plant species richness, although the magnitude of their effects can largely depend on ecosystem and herbivore characteristics. It has been demonstrated that the combined effect of primary productivity and body size is critical when assessing the impact of herbivores on plant richness of perennial-dominated grasslands; however, the interaction of site productivity and herbivore size as determinants of plant richness in annual-dominated pastures remains unknown. We experimentally partitioned primary productivity and herbivore body size (sheep and wild rabbits) to study the effect of herbivores on the plant species richness of a Mediterranean semiarid annual plant community in central Spain over six years. We also analyzed the effect of grazing and productivity on the evenness and species composition of the plant community, and green cover, litter, and plant height. We found that plant richness was higher where the large herbivore was present at high-productivity sites but barely changed at low productivity. The small herbivore did not affect species richness at either productivity site despite its large effects on species composition. We propose that adaptations to resource scarcity and herbivory prevented plant richness changes at low-productivity sites, whereas litter accumulation in the absence of herbivores decreased plant richness at high productivity. Our results are consistent with predictions arising from a long history of grazing and highlight the importance of both large and small herbivores to the maintenance of plant diversity of Mediterranean annual-dominated pastures. PMID:23090759

  18. Indirect effects of predators control herbivore richness and abundance in a benthic eelgrass (Zostera marina) mesograzer community.

    Science.gov (United States)

    Amundrud, Sarah L; Srivastava, Diane S; O'Connor, Mary I

    2015-07-01

    Herbivore communities can be sensitive to changes in predator pressure (top-down effects) and resource availability (bottom-up effects) in a wide range of systems. However, it remains unclear whether such top-down and bottom-up effects reflect direct impacts of predators and/or resources on herbivores, or are indirect, reflecting altered interactions among herbivore species. We quantified direct and indirect effects of bottom-up and top-down processes on an eelgrass (Zostera marina) herbivore assemblage. In a field experiment, we factorially manipulated water column nutrients (with Osmocote(™) slow-release fertilizer) and predation pressure (with predator exclusion cages) and measured the effects on herbivore abundance, richness and beta diversity. We examined likely mechanisms of community responses by statistically exploring the response of individual herbivore species to trophic manipulations. Predators increased herbivore richness and total abundance, in both cases through indirect shifts in community composition. Increases in richness occurred through predator suppression of common gammarid amphipod species (Monocorophium acherusicum and Photis brevipes), permitting the inclusion of rarer gammarid species (Aoroides columbiae and Pontogeneia rostrata). Increased total herbivore abundance reflected increased abundance of a caprellid amphipod species (Caprella sp.), concurrent with declines in the abundance of other common species. Furthermore, predators decreased beta diversity by decreasing variability in Caprella sp. abundance among habitat patches. Osmocote(™) fertilization increased nutrient concentrations locally, but nutrients dissipated to background levels within 3 m of the fertilizer. Nutrient addition weakly affected the herbivore assemblage, not affecting richness and increasing total abundance by increasing one herbivore species (Caprella sp.). Nutrient addition did not affect beta diversity. We demonstrated that assemblage-level effects of

  19. Scientific Opinion supplementing the conclusions of the environmental risk assessment and risk management recommendations for the cultivation of the genetically modified insect resistant maize Bt11 and MON 810

    OpenAIRE

    EFSA Panel on Genetically Modified Organisms (GMO)

    2012-01-01

    The EFSA GMO Panel was asked by the European Commission to apply its mathematical model to simulate and assess potential adverse effects resulting from the exposure of non-target Lepidoptera to maize Bt11 or MON 810 pollen under hypothetical agricultural conditions, and to provide information on the factors affecting the insect resistance management plan, additional to that in its 2011 Statement supplementing the evaluation of the environmental risk assessment and risk management recommendati...

  20. The European corn borer (Ostrinia nubilalis, Hbn.), its susceptibility to the Bt-toxin Cry1F, its pheromone races and its gene flow in Europe in view of an insect resistance management

    OpenAIRE

    Gaspers, Claudia

    2010-01-01

    One of the most promising and effective method for a control of the maize pest, Ostrinia nubilalis (European corn borer; „ECB“), is the cultivation of Bt-maize, which expresses lepidoteran-specific toxins. For a sustainable use of this technology an insect resistance management (IRM) is required to delay resistance development of the target pest, because in the past insects have developed resistance to all major classes of chemical insecticides. As a consequence of the increasing cultivation ...

  1. Evaluating the spatio-temporal factors that structure network parameters of plant-herbivore interactions.

    Directory of Open Access Journals (Sweden)

    Antonio López-Carretero

    Full Text Available Despite the dynamic nature of ecological interactions, most studies on species networks offer static representations of their structure, constraining our understanding of the ecological mechanisms involved in their spatio-temporal stability. This is the first study to evaluate plant-herbivore interaction networks on a small spatio-temporal scale. Specifically, we simultaneously assessed the effect of host plant availability, habitat complexity and seasonality on the structure of plant-herbivore networks in a coastal tropical ecosystem. Our results revealed that changes in the host plant community resulting from seasonality and habitat structure are reflected not only in the herbivore community, but also in the emergent properties (network parameters of the plant-herbivore interaction network such as connectance, selectiveness and modularity. Habitat conditions and periods that are most stressful favored the presence of less selective and susceptible herbivore species, resulting in increased connectance within networks. In contrast, the high degree of selectivennes (i.e. interaction specialization and modularity of the networks under less stressful conditions was promoted by the diversification in resource use by herbivores. By analyzing networks at a small spatio-temporal scale we identified the ecological factors structuring this network such as habitat complexity and seasonality. Our research offers new evidence on the role of abiotic and biotic factors in the variation of the properties of species interaction networks.

  2. 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

  3. Synergistic effects of three Piper amides on generalist and specialist herbivores.

    Science.gov (United States)

    Dyer, L A; Dodson, C D; Stireman, J O; Tobler, M A; Smilanich, A M; Fincher, R M; Letourneau, D K

    2003-11-01

    The tropical rainforest shrub Piper cenocladum, which is normally defended against herbivores by a mutualistic ant, contains three amides that have various defensive functions. While the ants are effective primarily against specialist herbivores, we hypothesized that these secondary compounds would be effective against a wider range of insects, thus providing a broad array of defenses against herbivores. We also tested whether a mixture of amides would be more effective against herbivores than individual amides. Diets spiked with amides were offered to five herbivores: a naïve generalist caterpillar (Spodoptera frugiperda), two caterpillar species that are monophagous on P. cenocladum (Eois spp.), leaf-cutting ants (Atta cephalotes), and an omnivorous ant (Paraponera clavata). Amides had negative effects on all insects, whether they were naïve, experienced, generalized, or specialized feeders. For Spodoptera, amide mixtures caused decreased pupal weights and survivorship and increased development times. Eois pupal weights, larval mass gain, and development times were affected by additions of individual amides, but increased parasitism and lower survivorship were caused only by the amide mixture. Amide mixtures also deterred feeding by the two ant species, and crude plant extracts were strongly deterrent to P. clavata. The mixture of all three amides had the most dramatic deterrent and toxic effects across experiments, with the effects usually surpassing expected additive responses, indicating that these compounds can act synergistically against a wide array of herbivores. PMID:14682530

  4. Rapidly increasing macroalgal cover not related to herbivorous fishes on Mesoamerican reefs.

    Science.gov (United States)

    Suchley, Adam; McField, Melanie D; Alvarez-Filip, Lorenzo

    2016-01-01

    Long-term phase shifts from coral to macroalgal dominated reef systems are well documented in the Caribbean. Although the impact of coral diseases, climate change and other factors is acknowledged, major herbivore loss through disease and overfishing is often assigned a primary role. However, direct evidence for the link between herbivore abundance, macroalgal and coral cover is sparse, particularly over broad spatial scales. In this study we use a database of coral reef surveys performed at 85 sites along the Mesoamerican Reef of Mexico, Belize, Guatemala and Honduras, to examine potential ecological links by tracking site trajectories over the period 2005-2014. Despite the long-term reduction of herbivory capacity reported across the Caribbean, the Mesoamerican Reef region displayed relatively low macroalgal cover at the onset of the study. Subsequently, increasing fleshy macroalgal cover was pervasive. Herbivorous fish populations were not responsible for this trend as fleshy macroalgal cover change was not correlated with initial herbivorous fish biomass or change, and the majority of sites experienced increases in macroalgae browser biomass. This contrasts the coral reef top-down herbivore control paradigm and suggests the role of external factors in making environmental conditions more favourable for algae. Increasing macroalgal cover typically suppresses ecosystem services and leads to degraded reef systems. Consequently, policy makers and local coral reef managers should reassess the focus on herbivorous fish protection and consider complementary measures such as watershed management in order to arrest this trend. PMID:27280075

  5. Rapidly increasing macroalgal cover not related to herbivorous fishes on Mesoamerican reefs

    Science.gov (United States)

    Suchley, Adam; McField, Melanie D.

    2016-01-01

    Long-term phase shifts from coral to macroalgal dominated reef systems are well documented in the Caribbean. Although the impact of coral diseases, climate change and other factors is acknowledged, major herbivore loss through disease and overfishing is often assigned a primary role. However, direct evidence for the link between herbivore abundance, macroalgal and coral cover is sparse, particularly over broad spatial scales. In this study we use a database of coral reef surveys performed at 85 sites along the Mesoamerican Reef of Mexico, Belize, Guatemala and Honduras, to examine potential ecological links by tracking site trajectories over the period 2005–2014. Despite the long-term reduction of herbivory capacity reported across the Caribbean, the Mesoamerican Reef region displayed relatively low macroalgal cover at the onset of the study. Subsequently, increasing fleshy macroalgal cover was pervasive. Herbivorous fish populations were not responsible for this trend as fleshy macroalgal cover change was not correlated with initial herbivorous fish biomass or change, and the majority of sites experienced increases in macroalgae browser biomass. This contrasts the coral reef top-down herbivore control paradigm and suggests the role of external factors in making environmental conditions more favourable for algae. Increasing macroalgal cover typically suppresses ecosystem services and leads to degraded reef systems. Consequently, policy makers and local coral reef managers should reassess the focus on herbivorous fish protection and consider complementary measures such as watershed management in order to arrest this trend. PMID:27280075

  6. Integration and inheritance stability of foreign Bt toxin gene in the bivalent insectresistant transgenic cotton plants

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    Genetic and expressional stability of Bt toxin gene is crucial for the breeding of insect-resistant transgenic cotton varieties and their commercialization. Genomic Southern blot analysis of R3, R4 and R5 generations of bivalent transgenic insect-resistant cotton plants was done in order to determine the integration, the copy number and the inheritance stability of Bt toxin gene in the transgenic cotton plants. The results indicated that there was a 4.7 kb positive band in the Southern blot when the genomic DNA of the bivalent transgenic insect-resistant cotton plants and the positive control (the plasmid) were digested with HindⅢ respectively. This result proved that the Bt toxin gene had been integrated into the genome of the cotton in full length.There is only one Xho I restriction site in the Bt toxin gene.Southern blot analysis indicated that many copies of Bt toxin gene had been integrated into the genome of the cotton when the genomic DNA of transgenic plants was digested with Xho I. Among them, there were four copies (about 17.7, 8,5.5 and 4.7 kb in size) existing in all the tested plants of R3,R4 and R5 generations. The preliminary conclusion was that there were more than four copies of Bt toxin gene integrated into the genome of the cotton, among them, more than one copy can express and inherit steadily. This result provides a scientific basis for the breeding of the bivalent insect-resistant transgenic cotton plants and its commercialization.``

  7. Impact of efficient refuge policies for Bt cotton in India on world cotton trade

    OpenAIRE

    Singla, Rohit; Johnson, Phillip N.; Misra, Sukant K.

    2010-01-01

    India is a major cotton producing country in the world along with the U.S. and China. A change in the supply of and demand for cotton in the Indian market has the potential to have an impact on world cotton trade. This study evaluates the implications of efficient Bt cotton refuge policies in India on world and U.S. cotton markets. It can be hypothesized that increased refuge requirements for Bt cotton varieties in India could decrease the world supply of cotton because of the lower yield pot...

  8. BT-Nurse: computer generation of natural language shift summaries from complex heterogeneous medical data

    OpenAIRE

    Hunter, James; Freer, Yvonne; Gatt, Albert; Reiter, Ehud; Sripada, Somayajulu; Sykes, Cindy; Westwater, Dave

    2011-01-01

    The BT-Nurse system uses data-to-text technology to automatically generate a natural language nursing shift summary in a neonatal intensive care unit (NICU). The summary is solely based on data held in an electronic patient record system, no additional data-entry is required. BT-Nurse was tested for two months in the Royal Infirmary of Edinburgh NICU. Nurses were asked to rate the understandability, accuracy, and helpfulness of the computer-generated summaries; they were also asked for free-t...

  9. Initial mechanisms for the decomposition of electronically excited energetic materials: 1,5′-BT, 5,5′-BT, and AzTT

    Energy Technology Data Exchange (ETDEWEB)

    Yuan, Bing; Yu, Zijun; Bernstein, Elliot R., E-mail: erb@lamar.Colostate.edu [Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872 (United States)

    2015-03-28

    Decomposition of nitrogen-rich energetic materials 1,5′-BT, 5,5′-BT, and AzTT (1,5′-Bistetrazole, 5,5′-Bistetrazole, and 5-(5-azido-(1 or 4)H-1,2,4-triazol-3-yl)tetrazole, respectively), following electronic state excitation, is investigated both experimentally and theoretically. The N{sub 2} molecule is observed as an initial decomposition product from the three materials, subsequent to UV excitation, with a cold rotational temperature (<30 K). Initial decomposition mechanisms for these three electronically excited materials are explored at the complete active space self-consistent field (CASSCF) level. Potential energy surface calculations at the CASSCF(12,8)/6-31G(d) level illustrate that conical intersections play an essential role in the decomposition mechanism. Electronically excited S{sub 1} molecules can non-adiabatically relax to their ground electronic states through (S{sub 1}/S{sub 0}){sub CI} conical intersections. 1,5′-BT and 5,5′-BT materials have several (S{sub 1}/S{sub 0}){sub CI} conical intersections between S{sub 1} and S{sub 0} states, related to different tetrazole ring opening positions, all of which lead to N{sub 2} product formation. The N{sub 2} product for AzTT is formed primarily by N–N bond rupture of the –N{sub 3} group. The observed rotational energy distributions for the N{sub 2} products are consistent with the final structures of the respective transition states for each molecule on its S{sub 0} potential energy surface. The theoretically derived vibrational temperature of the N{sub 2} product is high, which is similar to that found for energetic salts and molecules studied previously.

  10. Initial mechanisms for the decomposition of electronically excited energetic materials: 1,5′-BT, 5,5′-BT, and AzTT

    International Nuclear Information System (INIS)

    Decomposition of nitrogen-rich energetic materials 1,5′-BT, 5,5′-BT, and AzTT (1,5′-Bistetrazole, 5,5′-Bistetrazole, and 5-(5-azido-(1 or 4)H-1,2,4-triazol-3-yl)tetrazole, respectively), following electronic state excitation, is investigated both experimentally and theoretically. The N2 molecule is observed as an initial decomposition product from the three materials, subsequent to UV excitation, with a cold rotational temperature (<30 K). Initial decomposition mechanisms for these three electronically excited materials are explored at the complete active space self-consistent field (CASSCF) level. Potential energy surface calculations at the CASSCF(12,8)/6-31G(d) level illustrate that conical intersections play an essential role in the decomposition mechanism. Electronically excited S1 molecules can non-adiabatically relax to their ground electronic states through (S1/S0)CI conical intersections. 1,5′-BT and 5,5′-BT materials have several (S1/S0)CI conical intersections between S1 and S0 states, related to different tetrazole ring opening positions, all of which lead to N2 product formation. The N2 product for AzTT is formed primarily by N–N bond rupture of the –N3 group. The observed rotational energy distributions for the N2 products are consistent with the final structures of the respective transition states for each molecule on its S0 potential energy surface. The theoretically derived vibrational temperature of the N2 product is high, which is similar to that found for energetic salts and molecules studied previously

  11. Spatial Distribution of Eggs of Alabama argillacea Hübner and Heliothis virescens Fabricius (Lepidoptera: Noctuidae) on Bt and non-Bt Cotton.

    Science.gov (United States)

    Rodrigues, Tatiana R; Fernandes, Marcos G; Degrande, Paulo E; Mota, Thiago A

    2015-01-01

    Among the options to control Alabama argillacea (Hübner, 1818) and Heliothis virescens (Fabricius, 1781) on cotton, insecticide spraying and biological control have been extensively used. The GM'Bt' cotton has been introduced as an extremely viable alternative, but it is yet not known how transgenic plants affect populations of organisms that are interrelated in an agroecosystem. For this reason, it is important to know how the spatial arrangement of pests and beneficial insect are affected, which may call for changes in the methods used for sampling these species. This study was conducted with the goal to investigate the pattern of spatial distribution of eggs of A. argillacea and H. virescens in DeltaOpal™ (non-Bt) and DP90B™ Bt cotton cultivars. Data were collected during the agricultural year 2006/2007 in two areas of 5,000 m2, located in in the district of Nova América, Caarapó municipality. In each sampling area, comprising 100 plots of 50 m2, 15 evaluations were performed on two plants per plot. The sampling consisted in counting the eggs. The aggregation index (variance/mean ratio, Morisita index and exponent k of the negative binomial distribution) and chi-square fit of the observed and expected values to the theoretical frequency distribution (Poisson, Binomial and Negative Binomial Positive), showed that in both cultivars, the eggs of these species are distributed according to the aggregate distribution model, fitting the pattern of negative binomial distribution. PMID:26628025

  12. Transgenic cry1C(⁎) gene rough rice line T1C-19 does not change the host preferences of the non-target stored product pest, Rhyzopertha dominica (Fabricius) (Coleoptera: Bostrichidae), and its parasitoid wasp, Anisopteromalus calandrae (Howard) (Hymenoptera: Pteromalidae).

    Science.gov (United States)

    Sun, Xiao; Yan, Miao-Jun; Zhang, Aijun; Wang, Man-Qun

    2015-10-01

    Rough rice grains are often stored for extended periods before they are used or consumed. However, during storage, the rough rice is vulnerable to insect infestation, resulting in significant economic loss. Previous studies have shown that volatiles cues, physical characteristics, and taste chemicals on the grains could be the important key behavior factors for storage insect pests to locate the hosts and select oviposition sites. It is also well known that the transgenic Bt rough rice line T1C-19, which expresses a cry1C(⁎) gene has a high resistance to Lepidoptera pests. However, there were no evidences to show the consequences of host preference for non-target insect pests after growing Bt transgenic rice. In this study, the potential key factors of Bt rough rice were investigated for their impacts on the behaviors of non-target pest lesser grain borer Rhyzopertha dominica, the main weevil pest of grain and its parasitic wasps Anisopteromalus calandrae, the natural enemy of the beetle. Both electronic nose and electronic tongue analyses showed that the parameters of Bt rough rice were analogous to those of the non-Bt rough rice. The volatile profiles of Bt and non-Bt rough rice examined by gas chromatographic mass spectrometry (GC-MS) were similar. For most volatile compounds, there were no significantly quantitative differences in compound quantities between Bt and non-Bt rough rice. The densities of sclereids and trichomes on the rough rice husk surface were statistically equal in Bt and non-Bt rough rice. The non-target pest, R. dominica, and its parasitoid wasp, A. calandrae, were attracted to both rough rice and could not distinguish the transgenic T1C-19 from the isogenic rough rice. These results demonstrated that Bt rough rice has no negative impacts on the host preference behaviors of non-target stored product pest R. dominica and its parasitoid A. calandrae. PMID:26150137

  13. Chemical phenotype matching between a plant and its insect herbivore.

    Science.gov (United States)

    Berenbaum, M R; Zangerl, A R

    1998-11-10

    Two potential outcomes of a coevolutionary interaction are an escalating arms race and stable cycling. The general expectation has been that arms races predominate in cases of polygenic inheritance of resistance traits and permanent cycling predominates in cases in which resistance is controlled by major genes. In the interaction between Depressaria pastinacella, the parsnip webworm, and Pastinaca sativa, the wild parsnip, traits for plant resistance to insect herbivory (production of defensive furanocoumarins) as well as traits for herbivore "virulence" (ability to metabolize furanocoumarins) are characterized by continuous heritable variation. Furanocoumarin production in plants and rates of metabolism in insects were compared among four midwestern populations; these traits then were classified into four clusters describing multitrait phenotypes occurring in all or most of the populations. When the frequency of plant phenotypes belonging to each of the clusters is compared with the frequency of the insect phenotypes in each of the clusters across populations, a remarkable degree of frequency matching is revealed in three of the populations. That frequencies of phenotypes vary among populations is consistent with the fact that spatial variation occurs in the temporal cycling of phenotypes; such processes contribute in generating a geographic mosaic in this coevolutionary interaction on the landscape scale. Comparisons of contemporary plant phenotype distributions with phenotypes of herbarium specimens collected 9-125 years ago from across a similar latitudinal gradient, however, suggest that for at least one resistance trait-sphondin concentration-interactions with webworms have led to escalatory change. PMID:9811871

  14. Ecological specialisation in habitat selection within a macropodid herbivore guild.

    Science.gov (United States)

    Garnick, Sarah; Di Stefano, Julian; Elgar, Mark A; Coulson, Graeme

    2016-03-01

    Specialist species show stronger resource selection, narrower niches and lower niche overlap than generalist species. We examined ecological specialisation with respect to habitat selection in a macropodid community comprising the western grey kangaroo Macropus fuliginosus, red-necked wallaby M. rufogriseus and swamp wallaby Wallabia bicolor in the Grampians National Park, Victoria, Australia. We used radio tracking to quantify habitat selection. We predicted that because the fitness benefits of generalisation and specialisation differ, there would be a mix of generalised and specialised species in our community. As all three macropodid species show marked sexual dimorphism, we also expected that they would show sex-based specialisation. Finally, because many large herbivores select different habitats for foraging and resting, we predicted that our species would specialise on a subset of their overall selected habitat based on activity period (diurnal or nocturnal). All three species specialised on the available resources to some degree. Western grey kangaroos were specialists, at least during the active period. Niche data for the two wallaby species were harder to interpret so we could not determine their degree of specialisation. Within species, we found no evidence of sex-based specialisation. However, we found clear evidence of specialisation by activity period in western grey kangaroos and red-necked wallabies, but not in swamp wallabies. The strength of behavioural decisions made during the active period in influencing specialisation points to the likelihood that bottom-up processes regulate this community. PMID:26621691

  15. Differential effects of indole and aliphatic glucosinolates on lepidopteran herbivores.

    Science.gov (United States)

    Müller, René; de Vos, Martin; Sun, Joel Y; Sønderby, Ida E; Halkier, Barbara A; Wittstock, Ute; Jander, Georg

    2010-08-01

    Glucosinolates are a diverse group of defensive secondary metabolites that is characteristic of the Brassicales. Arabidopsis thaliana (L.) Heynh. (Brassicaceae) lines with mutations that greatly reduce abundance of indole glucosinolates (cyp79B2 cyp79B3), aliphatic glucosinolates (myb28 myb29), or both (cyp79B2 cyp79B3 myb28 myb29) make it possible to test the in vivo defensive function of these two major glucosinolate classes. In experiments with Lepidoptera that are not crucifer-feeding specialists, aliphatic and indole glucosinolates had an additive effect on Spodoptera exigua (Hübner) (Lepidoptera: Noctuidae) larval growth, whereas Trichoplusia ni (Hübner) (Lepidoptera: Noctuidae) and Manduca sexta (L.) (Lepidoptera: Sphingidae) were affected only by the absence of aliphatic glucosinolates. In the case of two crucifer-feeding specialists, Pieris rapae (L.) (Lepidoptera: Pieridae) and Plutella xylostella (L.) (Lepidoptera: Plutellidae), there were no major changes in larval performance due to decreased aliphatic and/or indole glucosinolate content. Nevertheless, choice tests show that aliphatic and indole glucosinolates act in an additive manner to promote larval feeding of both species and P. rapae oviposition. Together, these results support the hypothesis that a diversity of glucosinolates is required to limit the growth of multiple insect herbivores. PMID:20617455

  16. 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

  17. Decoupled form and function in disparate herbivorous dinosaur clades

    Science.gov (United States)

    Lautenschlager, Stephan; Brassey, Charlotte A.; Button, David J.; Barrett, Paul M.

    2016-05-01

    Convergent evolution, the acquisition of morphologically similar traits in unrelated taxa due to similar functional demands or environmental factors, is a common phenomenon in the animal kingdom. Consequently, the occurrence of similar form is used routinely to address fundamental questions in morphofunctional research and to infer function in fossils. However, such qualitative assessments can be misleading and it is essential to test form/function relationships quantitatively. The parallel occurrence of a suite of morphologically convergent craniodental characteristics in three herbivorous, phylogenetically disparate dinosaur clades (Sauropodomorpha, Ornithischia, Theropoda) provides an ideal test case. A combination of computational biomechanical models (Finite Element Analysis, Multibody Dynamics Analysis) demonstrate that despite a high degree of morphological similarity between representative taxa (Plateosaurus engelhardti, Stegosaurus stenops, Erlikosaurus andrewsi) from these clades, their biomechanical behaviours are notably different and difficult to predict on the basis of form alone. These functional differences likely reflect dietary specialisations, demonstrating the value of quantitative biomechanical approaches when evaluating form/function relationships in extinct taxa.

  18. Herbivore population regulation and resource heterogeneity in a stochastic environment.

    Science.gov (United States)

    Hempson, G P; Illius, A W; Hendricks, H H; Bond, W J; Vetter, S

    2015-08-01

    Large-mammal herbivore populations are subject to the interaction of internal density-dependent processes and external environmental stochasticity. We disentangle these processes by linking consumer population dynamics, in a highly stochastic environment, to the availability of their key forage resource via effects on body condition and subsequent fecundity and mortality rates. Body condition and demographic rate data were obtained by monitoring 500 tagged female goats in the Richtersveld National Park, South Africa, over a three-year period. Identifying the key resource and pathway to density dependence for a population allows environmental stochasticity to be partitioned into that which has strong feedbacks to population stability, and that which does not. Our data reveal a density- dependent seasonal decline in goat body condition in response to concomitant density-dependent depletion of the dry-season forage resource. The loss in body condition reduced density-dependent pregnancy rates, litter sizes, and pre-weaning survival. Survival was lowest following the most severe dry season and for juveniles. Adult survival in the late-dry season depended on body condition in the mid-dry season. Population growth was determined by the length of the dry season and the population size in the previous year. The RNP goat population is thereby dynamically coupled primarily to its dry-season forage resource. Extreme environmental variability thus does not decouple consumer resource dynamics, in contrast to the views of nonequilibrium protagonists. PMID:26405742

  19. Decoupled form and function in disparate herbivorous dinosaur clades.

    Science.gov (United States)

    Lautenschlager, Stephan; Brassey, Charlotte A; Button, David J; Barrett, Paul M

    2016-01-01

    Convergent evolution, the acquisition of morphologically similar traits in unrelated taxa due to similar functional demands or environmental factors, is a common phenomenon in the animal kingdom. Consequently, the occurrence of similar form is used routinely to address fundamental questions in morphofunctional research and to infer function in fossils. However, such qualitative assessments can be misleading and it is essential to test form/function relationships quantitatively. The parallel occurrence of a suite of morphologically convergent craniodental characteristics in three herbivorous, phylogenetically disparate dinosaur clades (Sauropodomorpha, Ornithischia, Theropoda) provides an ideal test case. A combination of computational biomechanical models (Finite Element Analysis, Multibody Dynamics Analysis) demonstrate that despite a high degree of morphological similarity between representative taxa (Plateosaurus engelhardti, Stegosaurus stenops, Erlikosaurus andrewsi) from these clades, their biomechanical behaviours are notably different and difficult to predict on the basis of form alone. These functional differences likely reflect dietary specialisations, demonstrating the value of quantitative biomechanical approaches when evaluating form/function relationships in extinct taxa. PMID:27199098

  20. Delta's Key to the Next Generation TOEFL[R] Test: Essential Grammar for the iBT

    Science.gov (United States)

    Gallagher, Nancy

    2012-01-01

    Although the TOEFL iBT does not have a discrete grammar section, knowledge of English sentence structure is important throughout the test. Essential Grammar for the iBT reviews the skills that are fundamental to success on tests. Content includes noun and verb forms, clauses, agreement, parallel structure, punctuation, and much more. The book may…

  1. Effects of Bacillus thuringiensis (Bt) corn on soil Folsomia fimetaria, Folsomia candida (Collembola), Hypoaspis aculeifer (Acarina) and Enchytraeus crypticus (Oligochaeta)

    DEFF Research Database (Denmark)

    Ke, X.; Krogh, P. H.

    The effects of the Cry1Ab toxin from Bacillus thuringiensis (corn variety Cascade Bt MON810 and DeKalb variety 618 Bt) were studied on survival and reproduction of the soil collembolan Folsomia fimetaria, Folsomia candida, the collembolan predator mite Hypoaspis aculeifer and enchytraeids...

  2. Part II. Mitochondrial mutational status of high nitric oxide adapted cell line BT-20 (BT-20-HNO) as it relates to human primary breast tumors.

    Science.gov (United States)

    De Vitto, H; Mendonça, B S; Elseth, K M; Vesper, B J; Portari, E A; Gallo, C V M; Paradise, W A; Rumjanek, F D; Radosevich, J A

    2013-02-01

    Mitochondria combine hydrogen and oxygen to produce heat and adenosine triphosphate (ATP). As a toxic by-product of oxidative phosphorylation (OXPHOS), mitochondria generate reactive oxygen species (ROS). These free radicals may cause damage to mitochondrial DNA (mtDNA) and other molecules in the cell. Nitric oxide (NO) plays an important role in the biology of human cancers, including breast cancer; however, it is still unclear how NO might affect the mitochondrial genome. The aim of the current study is to determine the role of mtDNA in the breast oncogenic process. Using DNA sequencing, we studied one breast cancer cell line as a model system to investigate the effects of oxidative stress. The BT-20 cell line was fully adapted to increasing concentrations of the NO donor DETA-NONOate and is referred to as BT-20-HNO, a high NO (HNO) cell line. The HNO cell line is biologically different from the "parent" cell line from which it originated. Moreover, we investigated 71 breast cancer biopsies and the corresponding noncancerous breast tissues. The free radical NO was able to generate somatic mtDNA mutations in the BT-20-HNO cell line that were missing in the BT-20 parent cell line. We identified two somatic mutations, A4767G and G13481A, which changed the amino acid residues. Another two point mutations were identified in the mtDNA initiation replication site at nucleotide 57 and at the 'hot spot' cytidine-rich D300-310 segment. Furthermore, the NO regulated the mtDNA copy number and selected different mtDNA populations by clonal expansion. Interestingly, we identified eight somatic mutations in the coding regions of mtDNAs of eight breast cancer patients (8/71, 11.2 %). All of these somatic mutations changed amino acid residues in the highly conserved regions of mtDNA which potentially leads to mitochondrial dysfunctions. The other two somatic mtDNA mutations in the displacement loop (D-loop) region [303:315 C(7-8)TC(6) and nucleotide 57] were distributed among 14

  3. No adaptation of a herbivore to a novel host but loss of adaptation to its native host

    OpenAIRE

    Grosman, A.H.; Molina-Rugama, A.J.; Mendes-Dias, R.; Sabelis, M. W.; Menken, S.B.J.; Pallini, A.; Janssen, A.

    2015-01-01

    Most herbivorous arthropods are host specialists and the question is which mechanisms drive the evolution of such specialization. The theory of antagonistic pleiotropy suggests that there is a trade-off between adaptation of herbivores to a novel host and their native host. The mutation accumulation hypothesis proposes that herbivores on a novel host lose their adaptation to the native host through the accumulation of mutations with negligible effects on performance on the novel host. Experim...

  4. Complex Effects of Fertilization on Plant and Herbivore Performance in the Presence of a Plant Competitor and Activated Carbon

    OpenAIRE

    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 ta...

  5. Growth, productivity, and competitiveness of introgressed weedy Brassica rapa hybrids selected for the presence of Bt cry1Ac and gfp transgenes.

    Science.gov (United States)

    Halfhill, Matthew D; Sutherland, Jamie P; Moon, Hong Seok; Poppy, Guy M; Warwick, Suzanne I; Weissinger, Arthur K; Rufty, Thomas W; Raymer, Paul L; Stewart, C Neal

    2005-09-01

    Concerns exist that transgenic crop x weed hybrid populations will be more vigorous and competitive with crops compared with the parental weed species. Hydroponic, glasshouse, and field experiments were performed to evaluate the effects of introgression of Bacillus thuringiensis (Bt) cry1Ac and green fluorescent protein (GFP) transgenes on hybrid productivity and competitiveness in four experimental Brassica rapa x transgenic Brassica napus hybrid generations (F1, BC1F1, BC2F1 and BC2F2). The average vegetative growth and nitrogen (N) use efficiency of transgenic hybrid generations grown under high N hydroponic conditions were lower than that of the weed parent (Brassica rapa, AA, 2n = 20), but similar to the transgenic crop parent, oilseed rape (Brassica napus, AACC, 2n = 38). No generational differences were detected under low N conditions. In two noncompetitive glasshouse experiments, both transgenic and nontransgenic BC2F2 hybrids had on average less vegetative growth and seed production than B. rapa. In two high intraspecific competition field experiments with varied herbivore pressure, BC2F2 hybrids produced less vegetative dry weight than B. rapa. The competitive ability of transgenic and nontransgenic BC2F2 hybrids against a neighbouring crop species were quantified in competition experiments that assayed wheat (Triticum aestivum) yield reductions under agronomic field conditions. The hybrids were the least competitive with wheat compared with parental Brassica competitors, although differences between transgenic and nontransgenic hybrids varied with location. Hybridization, with or without transgene introgression, resulted in less productive and competitive populations. PMID:16101783

  6. Effects of 90-Day Feeding of Transgenic Maize BT799 on the Reproductive System in Male Wistar Rats.

    Science.gov (United States)

    Guo, Qian-ying; He, Li-xia; Zhu, Han; Shang, Jun-li; Zhu, Ling-yan; Wang, Jun-bo; Li, Yong

    2015-12-01

    BT799 is a genetically modified (GM) maize plant that expresses the Cry1Ac gene from Bacillus thuringiensis (Bt). The Cry1Ac gene was introduced into maize line Zhen58 to encode the Bt crystal protein and thus produce insect-resistant maize BT799. Expression of Bt protein in planta confers resistance to Lepidopteran pests and corn rootworms. The present study was designed to investigate any potential effects of BT799 on the reproductive system of male rats and evaluate the nutritional value of diets containing BT799 maize grain in a 90-day subchronic rodent feeding study. Male Wistar rats were fed with diets containing BT799 maize flours or made from its near isogenic control (Zhen58) at a concentration of 84.7%, nutritionally equal to the standard AIN-93G diet. Another blank control group of male rats were treated with commercial AIN-93G diet. No significant differences in body weight, hematology and serum chemistry results were observed between rats fed with the diets containing transgenic BT799, Zhen58 and the control in this 13-week feeding study. Results of serum hormone levels, sperm parameters and relative organ/body weights indicated no treatment-related side effects on the reproductive system of male rats. In addition, no diet-related changes were found in necropsy and histopathology examinations. Based on results of the current study, we did not find any differences in the parameters tested in our study of the reproductive system of male rats between BT799 and Zhen58 or the control. PMID:26633453

  7. Effects of 90-Day Feeding of Transgenic Maize BT799 on the Reproductive System in Male Wistar Rats

    Directory of Open Access Journals (Sweden)

    Qian-ying Guo

    2015-12-01

    Full Text Available BT799 is a genetically modified (GM maize plant that expresses the Cry1Ac gene from Bacillus thuringiensis (Bt. The Cry1Ac gene was introduced into maize line Zhen58 to encode the Bt crystal protein and thus produce insect-resistant maize BT799. Expression of Bt protein in planta confers resistance to Lepidopteran pests and corn rootworms. The present study was designed to investigate any potential effects of BT799 on the reproductive system of male rats and evaluate the nutritional value of diets containing BT799 maize grain in a 90-day subchronic rodent feeding study. Male Wistar rats were fed with diets containing BT799 maize flours or made from its near isogenic control (Zhen58 at a concentration of 84.7%, nutritionally equal to the standard AIN-93G diet. Another blank control group of male rats were treated with commercial AIN-93G diet. No significant differences in body weight, hematology and serum chemistry results were observed between rats fed with the diets containing transgenic BT799, Zhen58 and the control in this 13-week feeding study. Results of serum hormone levels, sperm parameters and relative organ/body weights indicated no treatment-related side effects on the reproductive system of male rats. In addition, no diet-related changes were found in necropsy and histopathology examinations. Based on results of the current study, we did not find any differences in the parameters tested in our study of the reproductive system of male rats between BT799 and Zhen58 or the control.

  8. Trade-off among different anti-herbivore defence strategies along an altitudinal gradient.

    Science.gov (United States)

    Dostálek, Tomáš; Rokaya, Maan Bahadur; Maršík, Petr; Rezek, Jan; Skuhrovec, Jiří; Pavela, Roman; Münzbergová, Zuzana

    2016-01-01

    The type and intensity of plant-herbivore interactions are likely to be altered under climate change as a consequence of differential dispersal rates of plants and their herbivores. Here, we studied variation in herbivore damage on Salvia nubicola in the field and compared its growth and defence strategies against herbivores in controlled conditions using seeds from populations along a broad altitudinal gradient. Our work is one of the first studies to simultaneously measure complex intraspecific variation in plant growth, direct and indirect defences as well as plant tolerance (ability to regrow) as a consequence of herbivore attack simulated by clipping. In the field, we found that plants experienced higher herbivore pressure in lower altitudes. In the greenhouse, plants grown from seeds collected in lower-altitude populations grew better and produced a higher content of phenolic compounds (direct defence) and volatile organic compounds (indirect defence) in response to simulated herbivory. However, there were no differences in tolerance and effect of S. nubicola extracts on the model generalist herbivore Spodoptera littoralis (direct defence) along the altitudinal gradient. Although we found that S. nubicola developed a range of defence strategies, the strategies do not seem to be used simultaneously in all populations even though most of them are correlated with altitudinal gradient. Our finding is in agreement with the current knowledge that co-expression of multiple defences might be costly for a plant, since investment in defensive traits is assumed to reduce the resource availability for growth and reproduction. Our study thus shows the importance of simultaneous study of different defence strategies since understanding these trade-offs could be necessary for detecting the mechanisms by which plants are able to cope with future climate change. PMID:27169609

  9. Odor uniformity among tomato individuals in response to herbivore depends on insect species.

    Directory of Open Access Journals (Sweden)

    Alicia Bautista-Lozada

    Full Text Available Plants produce specific volatile organic compound (VOC blends in response to herbivory. Herbivore-induced blends may prime the plant for future attack or attract carnivorous insects; these responses have been considered adaptive for plants. If herbivores differentially modify the VOC emission among individuals within a group of plants they feed upon, then plant responses to herbivores will not only produce specific blends but also variation in odor among individuals, i.e. individuals smell the same, then having a uniform odor. We investigated the VOC emission variation or uniformity among tomato individuals (Solanum lycopersicum L. cv. Castlemart in response to moderate wounding by (1 nymphs of the psyllid Bactericera cockerelli (Sulc. (TP; (2 Lepidoptera chewing-feeding larvae of Fall Armyworm (Spodoptera frugiperda Smith (FAW and (3 of Cabbage Looper (Trichoplusia ni Hübner (CL, and (4 mechanical damage (MD. We used a ratio-based analysis to compare the fold-change in concentration from constitutive to induced VOC emission. We also used size and shape analysis to compare the emission of damaged and non-damaged individuals. Aside of finding herbivore-specific blends in line with other studies, we found patterns not described previously. We detected constitutive and induced odor variation among individuals attacked by the same herbivore, with the induced odor uniformity depending on the herbivore identity. We also showed that the fold-change of VOCs from constitutive to induced state differed among individuals independently of the uniformity of the blends before herbivore attack. We discuss our findings in the context of the ecological roles of VOCs in plant-plant and plant-carnivore insects' interactions.

  10. Sporormiella as a proxy for non-mammalian herbivores in island ecosystems

    Science.gov (United States)

    Wood, Jamie R.; Wilmshurst, Janet M.; Worthy, Trevor H.; Cooper, Alan

    2011-04-01

    Spores of the dung-fungi Sporormiella are routinely used as a proxy for past megaherbivore biomass and to pinpoint the timing of extinctions. Further ecological insight can also be gained into the impacts that followed initial human arrival in a region through correlation of spore abundance with other proxies (e.g. pollen, charcoal). Currently, the use of Sporormiella as a palaeoecological proxy has been restricted to landmasses where large-herbivore guilds are dominated by mammals. Here, we use New Zealand as a case study to show that the method can also be applied effectively to islands dominated by large avian herbivores. We examine 44 dung samples from 7 localities to show that Sporormiella spores were widely distributed in the dung of endemic avian herbivores (South Island takahe ( Porphyrio hochstetteri), kakapo ( Strigops habroptilus), and several species of extinct moa, identified by ancient DNA analysis). In addition, we show that Sporormiella spores in a forest soil core from the Murchison Mountains, South Island, accurately trace the post-settlement decline of native avian herbivores, and combined with high-resolution radiocarbon dating reveal severely reduced local herbivore populations by the late 17th Century AD. The spores also trace the subsequent spread of Red deer ( Cervus elaphus) introduced to the area in the early 20th Century AD. Our results suggest Sporormiella spores may provide a useful new tool for examining extinctions on numerous islands where terrestrial herbivore guilds were dominated by birds or reptiles. Our findings also highlight the need to consider entire herbivore communities (including birds and reptiles) when examining Late Pleistocene continental Sporormiella records, where the focus has often been tracing the decline of populations of large mammals.

  11. Trade-off among different anti-herbivore defence strategies along an altitudinal gradient

    Science.gov (United States)

    Dostálek, Tomáš; Rokaya, Maan Bahadur; Maršík, Petr; Rezek, Jan; Skuhrovec, Jiří; Pavela, Roman; Münzbergová, Zuzana

    2016-01-01

    The type and intensity of plant–herbivore interactions are likely to be altered under climate change as a consequence of differential dispersal rates of plants and their herbivores. Here, we studied variation in herbivore damage on Salvia nubicola in the field and compared its growth and defence strategies against herbivores in controlled conditions using seeds from populations along a broad altitudinal gradient. Our work is one of the first studies to simultaneously measure complex intraspecific variation in plant growth, direct and indirect defences as well as plant tolerance (ability to regrow) as a consequence of herbivore attack simulated by clipping. In the field, we found that plants experienced higher herbivore pressure in lower altitudes. In the greenhouse, plants grown from seeds collected in lower-altitude populations grew better and produced a higher content of phenolic compounds (direct defence) and volatile organic compounds (indirect defence) in response to simulated herbivory. However, there were no differences in tolerance and effect of S. nubicola extracts on the model generalist herbivore Spodoptera littoralis (direct defence) along the altitudinal gradient. Although we found that S. nubicola developed a range of defence strategies, the strategies do not seem to be used simultaneously in all populations even though most of them are correlated with altitudinal gradient. Our finding is in agreement with the current knowledge that co-expression of multiple defences might be costly for a plant, since investment in defensive traits is assumed to reduce the resource availability for growth and reproduction. Our study thus shows the importance of simultaneous study of different defence strategies since understanding these trade-offs could be necessary for detecting the mechanisms by which plants are able to cope with future climate change. PMID:27169609

  12. Decaying toxic wood as sodium supplement for herbivorous mammals in Gabon

    Science.gov (United States)

    IWATA, Yuji; NAKASHIMA, Yoshihiro; TSUCHIDA, Sayaka; NGUEMA, Pierre Philippe Mbehang; ANDO, Chieko; USHIDA, Kazunari; YAMAGIWA, Juichi

    2015-01-01

    African rainforest harbors herbivores at high density. However, because plants and soils typically lack in some essential minerals, rainforest is not always a suitable habitat for herbivores. How they fulfill the mineral requirements is therefore an important question to animal ecology and conservation. Although large marshes, called ‘bais’, are often mentioned as efficient mineral-resource, little information on other sodium resources has still been available. Our laboratory works and field surveys found that a peculiar item, decaying wood stumps of Anthostema aubryanum, played as a major sodium resource for herbivores in Moukalaba-Doudou National Park, Gabon. When A. aubryanum is alive, the sodium content of its bark is low and its latex is toxic. Sodium is accumulated in decaying stumps (mean=1,343 mg/kg dry matter). Eight herbivores visited stumps to ingest the dead wood. Fecal sample analysis revealed that western lowland gorillas, a species most-frequently using the stumps, consumed large amount of the dead wood as regular food. Our findings suggest that decaying A. aubryanum is critical sodium-resources and is a key species for herbivores in our study area. Importance of the A. aubryanum may be particularly large there, because it is a limited sodium-rich material that is available year round. Our study site is known as the site where the densities of several herbivores are among the highest at Central Africa. The relatively high herbivores density in our study site may partly depend on decaying A. aubryanum as sodium resources. PMID:25994487

  13. Draft Genome Sequence of Erwinia mallotivora BT-MARDI, Causative Agent of Papaya Dieback Disease.

    Science.gov (United States)

    Redzuan, R Ahmad; Abu Bakar, N; Rozano, L; Badrun, R; Mat Amin, N; Mohd Raih, M F

    2014-01-01

    Erwinia mallotivora was isolated from papaya trees infected with dieback disease, which were planted at the Malaysian Agricultural Research and Development Institute (MARDI), Malaysia. Here, we report a draft genome sequence of E. mallotivora BT-MARDI, which offers an important source of information for understanding pathogen and host interaction during papaya dieback development. PMID:24812220

  14. Subcellular Localization of Cadmium in Chlorella vulgaris Beijerinck Strain Bt-09

    Directory of Open Access Journals (Sweden)

    P.B. Lintongan

    2004-06-01

    Full Text Available Growth response curves of Chlorella vulgaris Beijerinck strain Bt-09 to sublethal concentrations of cadmium were evaluated. The growth responses of this microalgal isolate was determined through analysis of chlorophyll a levels. Cadmium was effectively taken up by the cells as determined by Flame Atomic Absorption Spectrophotometry (F-AAS. Subcellular fractionation was undertaken to locate sites that accumulate cadmium.

  15. Draft Genome Sequence of Erwinia mallotivora BT-MARDI, Causative Agent of Papaya Dieback Disease

    OpenAIRE

    Redzuan, R. Ahmad; Abu Bakar, N; Rozano, L.; Badrun, R.; Mat Amin, N.; Mohd Raih, M. F.

    2014-01-01

    Erwinia mallotivora was isolated from papaya trees infected with dieback disease, which were planted at the Malaysian Agricultural Research and Development Institute (MARDI), Malaysia. Here, we report a draft genome sequence of E. mallotivora BT-MARDI, which offers an important source of information for understanding pathogen and host interaction during papaya dieback development.

  16. The Reflexive Producer: The Influence of Farmer Knowledge upon the Use of Bt Corn

    Science.gov (United States)

    Kaup, Brent Z.

    2008-01-01

    This paper examines the influence of farmer knowledge upon decision making processes. Drawing upon the sociological debates around the ideas of reflexive modernity and biotechnology as well as from classic adoption and diffusion studies, I explore the influences upon farmers' use of "Bacillus thuringiensis" (Bt) corn. Utilizing survey data…

  17. Economic impacts and impact dynamics of Bt (Bacillus thuringiensis) cotton in India.

    Science.gov (United States)

    Kathage, Jonas; Qaim, Matin

    2012-07-17

    Despite widespread adoption of genetically modified crops in many countries, heated controversies about their advantages and disadvantages continue. Especially for developing countries, there are concerns that genetically modified crops fail to benefit smallholder farmers and contribute to social and economic hardship. Many economic studies contradict this view, but most of them look at short-term impacts only, so that uncertainty about longer-term effects prevails. We address this shortcoming by analyzing economic impacts and impact dynamics of Bt cotton in India. Building on unique panel data collected between 2002 and 2008, and controlling for nonrandom selection bias in technology adoption, we show that Bt has caused a 24% increase in cotton yield per acre through reduced pest damage and a 50% gain in cotton profit among smallholders. These benefits are stable; there are even indications that they have increased over time. We further show that Bt cotton adoption has raised consumption expenditures, a common measure of household living standard, by 18% during the 2006-2008 period. We conclude that Bt cotton has created large and sustainable benefits, which contribute to positive economic and social development in India. PMID:22753493

  18. Validating TOEFL[R] iBT Speaking and Setting Score Requirements for ITA Screening

    Science.gov (United States)

    Xi, Xiaoming

    2007-01-01

    Although the primary use of the speaking section of the Test of English as a Foreign Language Internet-based test (TOEFL[R] iBT Speaking) is to inform admissions decisions at English medium universities, it may also be useful as an initial screening measure for international teaching assistants (ITAs). This study provides criterion-related…

  19. TOEFL iBT Speaking Test Scores as Indicators of Oral Communicative Language Proficiency

    Science.gov (United States)

    Bridgeman, Brent; Powers, Donald; Stone, Elizabeth; Mollaun, Pamela

    2012-01-01

    Scores assigned by trained raters and by an automated scoring system (SpeechRater[TM]) on the speaking section of the TOEFL iBT[TM] were validated against a communicative competence criterion. Specifically, a sample of 555 undergraduate students listened to speech samples from 184 examinees who took the Test of English as a Foreign Language…

  20. Relationship of TOEFL iBT[R] Scores to Academic Performance: Some Evidence from American Universities

    Science.gov (United States)

    Cho, Yeonsuk; Bridgeman, Brent

    2012-01-01

    This study examined the relationship between scores on the TOEFL Internet-Based Test (TOEFL iBT[R]) and academic performance in higher education, defined here in terms of grade point average (GPA). The academic records for 2594 undergraduate and graduate students were collected from 10 universities in the United States. The data consisted of…

  1. BT CORN, REFUGES, AND MONARCH BUTTERFLIES: CHALLENGES FOR ENTOMOLOGISTS AND GROWERS

    Science.gov (United States)

    Transgenic corn with resistance to European corn borer (ECB) has been commercially available since 1996. Inserting a gene from the soil bacterium Bacillus thuringiensis (Bt) has genetically modified the corn plant to produce a protein that is toxic to many types of moth larvae, particularly ECB. As ...

  2. Host plant preference of spider mites on Bt-expressing and control potatoes

    Czech Academy of Sciences Publication Activity Database

    Zemek, Rostislav

    Coventry : University of Warwick, 2008. s. 61-61. [Annual Meeting of the Society for Invertebrate Pathology /41./ and International Conference on Bacillus thuringiensis Incorporating COST 862 Action: Bacterial Toxins for Insect Control /9./. 03.08.2008-07.08.2008, Coventry] Institutional research plan: CEZ:AV0Z50070508 Keywords : Bt-expressing Subject RIV: EH - Ecology, Behaviour

  3. Four-year study of the impact of Bt maize on Arthropod communities

    Czech Academy of Sciences Publication Activity Database

    Habuštová, Oxana; Doležal, Petr; Spitzer, Lukáš; Hussein, Hany; Turanli, Ferit; Růžička, Vlastimil; Sehnal, František

    Izmir: Entomological Society of Turkey, 2006. s. 129-129. [European Congress of Entomology /8./. 17.09.2006-22.09.2006, Izmir] R&D Projects: GA AV ČR(CZ) KJB6007304 Institutional research plan: CEZ:AV0Z50070508 Keywords : Bt maize Subject RIV: EH - Ecology, Behaviour

  4. Results of a four-year study of the impact of Bt maize on arthropod communities

    Czech Academy of Sciences Publication Activity Database

    Habuštová, Oxana; Hussein, Hany; Doležal, Petr; Spitzer, Lukáš; Růžička, Vlastimil

    České Budějovice: Biology Centre of Academy of Sciences of the Czech Republic, 2009 - (Sehnal, F.; Drobník, J.), s. 60-60 ISBN 978-80-86668-05-3 Institutional research plan: CEZ:AV0Z50070508 Keywords : Bt maize Subject RIV: GF - Plant Pathology, Vermin, Weed, Plant Protection

  5. Chinese-version Bt Cotton: How to Get the Benefits from IPR

    Institute of Scientific and Technical Information of China (English)

    X.J. Fang

    2007-01-01

    @@ Chinese scientists started to fully synthesize the Bacillus thuringiensis (Bt) Cry1A gene in 1991. By the end of 1992, Biotechnology Research Institute of Chinese Academy of Agricultural Sciences (BRI-CAAS) successfully synthesized the full size of GFM Cry1A gene, which was a fusion gene of Cry1A(b) and Cry1A(c).

  6. Incipient resistance of Helicoverpa punctigera to the Cry2Ab Bt toxin in Bollgard II cotton.

    Directory of Open Access Journals (Sweden)

    Sharon Downes

    Full Text Available Combinations of dissimilar insecticidal proteins ("pyramids" within transgenic plants are predicted to delay the evolution of pest resistance for significantly longer than crops expressing a single transgene. Field-evolved resistance to Bacillus thuringiensis (Bt transgenic crops has been reported for first generation, single-toxin varieties and the Cry1 class of proteins. Our five year data set shows a significant exponential increase in the frequency of alleles conferring Cry2Ab resistance in Australian field populations of Helicoverpa punctigera since the adoption of a second generation, two-toxin Bt cotton expressing this insecticidal protein. Furthermore, the frequency of cry2Ab resistance alleles in populations from cropping areas is 8-fold higher than that found for populations from non-cropping regions. This report of field evolved resistance to a protein in a dual-toxin Bt-crop has precisely fulfilled the intended function of monitoring for resistance; namely, to provide an early warning of increases in frequencies that may lead to potential failures of the transgenic technology. Furthermore, it demonstrates that pyramids are not 'bullet proof' and that rapid evolution to Bt toxins in the Cry2 class is possible.

  7. IMPACT OF BT ( BACILLUS THURINGIENSIS ) CROPS ON BAT ACTIVITY IN SOUTH TEXAS AGROECOSYSTEMS

    Science.gov (United States)

    The widespread adoption of transgenic insecticidal crops raises concerns that nontarget species may be harmed and food webs disrupted. The goal of this research is to determine how transgenic Bt (Bacillus thuringiensis) crops impact the activity of Brazilian freetailed bats (Tada...

  8. Call for Papers-Bt Research(ISSN 1925-1939)

    Institute of Scientific and Technical Information of China (English)

    2011-01-01

    Bt Research (ISSN 1925-1939) is a new launched, open access and peer reviewed journal that disseminates significant creative reviews and opinions or innovative research work in the area of BaeiUus thuringiensis, including the isolation and identification

  9. Tritrophic choice experiments with Bt plants, the diamondback moth (Plutella xylostella) and the parasitoid Cotesia plutellae

    NARCIS (Netherlands)

    Schuler, T.H.; Potting, R.P.J.; Denholm, I.; Clark, S.J.; Clark, A.J.; Stewart, C.N.; Poppy, G.M.

    2003-01-01

    Parasitoids are important natural enemies of many pest species and are used extensively in biological and integrated control programmes. Crop plants transformed to express toxin genes derived from Bacillus thuringiensis (Bt) provide high levels of resistance to certain pest species, which is likely

  10. Apparent diffusion coefficients in GEC ESTRO target volumes for image guided adaptive brachytherapy of locally advanced cervical cancer

    Energy Technology Data Exchange (ETDEWEB)

    Haack, Soeren (Dept. of Clinical Engineering, Aarhus Univ. Hospital (Denmark)), E-mail: Soeren.haack@stab.rm.dk; Morre Pedersen, Erik (Dept. of Radiology, Aarhus Sygehus, Aarhus Univ. Hospital (Denmark)); Jespersen, Sune N. (Center of Functionally Integrative Neuroscience, Aarhus Univ. Hospital (Denmark)); Kallehauge, Jesper F. (Dept. of Medical Physics, Aarhus Univ. Hospital (Denmark)); Lindegaard, Jacob Christian; Tanderup, Kari (Dept. of Oncology Aarhus Univ. Hospital (Denmark))

    2010-10-15

    Background and purpose. T2 weighted MRI is recommended for image guided adaptive brachytherapy (IGABT) in cervical cancer. Diffusion weighted imaging (DWI) and the derived apparent diffusion coefficient (ADC) may add additional biological information on tumour cell density. The purpose of this study was to evaluate the distribution of the ADC within target volumes as recommended by GEC-ESTRO: Gross Tumour Volume at BT (GTVBT), High-Risk Clinical Tumour Volume (HR-CTV) and Intermediate-Risk Clinical Target Volume (IR-CTV) and to evaluate the change of diffusion between fractions of IGABT. Material and methods. Fifteen patients with locally advanced cervical cancer were examined by MRI before their first (BT1) and second (BT2) fraction of IGABT, resulting in a total of 30 MR examinations including both T2 weighted and DWI sequences. The Apparent Diffusion Coefficient (ADC) was calculated by use of three levels of b-values (0, 600, 1000 s/mm2). ADC maps were constructed and fused with the GEC ESTRO target contours. The mean ADC value within each target volume was calculated. Furthermore, volumes of low diffusion (ADClow) were defined based on an ADC threshold of 1.2 x 10-3 mm2/s, and overlap with target volumes was evaluated. Change of ADC level in target volumes and change of ADClow volume from BT1 to BT2 was also evaluated. Results. The mean ADC was significantly lower in GTVBT than in HR-CTV (p<0.001) which again was significantly lower than in IR-CTV (p<0.001). There was no significant change of the ADClow volume or ADC level within each target structure between BT1 and BT2 (p=0.242). All three GEC-ESTRO volumes contained volumes with low diffusion. The GTVBT contained 37.2% volume of low diffusion, HR-CTV 20.3% and IR-CTV 10.8%. Conclusion. With DWI we were able to find a significant difference in ADC-values for the three different GEC ESTRO targets. This supports the assumption that the target volumes used for dose prescription in IGABT contain tissues with

  11. Transgenic wheat and non-target impacts on insect herbivores and food webs

    OpenAIRE

    Von Burg, S K

    2011-01-01

    This PhD thesis combines research on ecological risks of genetically modified (GM) plants with plant-insect interactions and food web ecology. In this chapter I will review the current global state of GM crops, give a short overview over the concerns about ecological impacts of GM plants and introduce the study system. At the end of the chapter the goals of this thesis are stated.

  12. 用合成多肽为半抗原制备Bt Cry1Ab的单克隆抗体%Preparation of the Monoclonal Antibody Against Bt Cry1Ab by Using Synthetic Peptide as Hapten

    Institute of Scientific and Technical Information of China (English)

    胡小元; 张岐蜀; 段伟; 姜国华; 李玲

    2013-01-01

    由于Bt Cry1Aa、Cry1Ab和Cry1Ac晶体蛋白之间具有很高的同源性(82%~90%),采用常规的单抗制备方法很难制取特异性强的Bt Cry1Ab单抗,为了制备抗Bt Cry1Ab蛋白的特异性单克隆抗体(MAB),本研究从NCBI获得了Bt Cry1Ab蛋白的氨基酸序列,根据ANTHEPORT和DNAStar软件对其抗原性、亲水性和表位性分析结果选定Bt Cry1Ab特异性肽段进行人工合成,并将其偶联于匙孔血蓝蛋白(KLH)免疫动物,应用细胞融合技术制备了抗该肽段的杂交瘤细胞22株.通过ELISA试验从中筛选出与Bt Cry1Ab天然蛋白产生特异性反应的单克隆抗体杂交瘤细胞株一株(3A10).经检测,其分泌的抗体亚类为IgG1型;轻链属κ型;杂交瘤细胞株染色体数目为89~108条;用其制作的腹水对Bt Cry1Ab合成肽的反应效价为1∶1×107;对Bt Cry1Ab天然蛋白的反应效价为1∶1×104;纯化后的抗体对Bt Cry1Ab合成肽的效价为1∶1×108;对Bt Cry1Ab天然蛋白的效价为1∶2×104.抗体的相对亲和力为0.5 μg/mL,对Bt Cry 1Ab蛋白的最低可检测值为10 ng/mL.ELISA结果显示,3A10杂交瘤细胞株所分泌的MAB能特异性识别合成肽和Bt Cry1Ab蛋白,而对同源的Cry1Ac和Cry1Aa蛋白无交叉反应;本研究所制备的Bt Cry1Ab单克隆抗体能够对常规棉和抗虫棉(Gossypium hirsutum L.)进行有效的区分,并且能特异性的识别其中的Bt Cry1Ab蛋白.%Because Bt Cry 1Aa, Cry 1Ab and Cry 1Ac share high sequence identity(82%~90%), it is difficult to prepare Bt Cry1 Ab monoclonal antibody that has highly specific by using conventional method. In order to prepare monoclonal antibody against Bt Cry1Ab, we acquired the amino acid sequence of Bt Cry1Ab protein from NCBI. According to the antigenicity, hydrophilicity and accessibility analyzed results by ANTHEPORT and DNAStar computer software, the specific peptide of Bt Cry1Ab was synthesized by a chemical process. The Bt Cry1Ab peptide was linked with carrier

  13. Food chemical discriminations by an herbivorous lizard, Corucia zebrata.

    Science.gov (United States)

    Cooper, W E

    2000-03-01

    Adjustment of chemosensory response to diet should be apparent in evolutionary changes corresponding to dietary shifts. Because most lizards are generalist predators of small animals, relationships between chemosensory behavior and diet are difficult to detect. Nevertheless, the evolution of herbivory by a small number of lizards provides an opportunity to detect any corresponding change in response to plant chemicals. I studied tongue-flicking and biting by the large, herbivorous scincid lizard Corucia zebrata in response to chemical cues from crickets, romaine lettuce, and control stimuli presented on cotton swabs. The skinks exhibited significantly stronger response to plant and animal chemicals than to controls for several variables: greater number of individuals that bit swabs, shorter latency to bite, greater rate of tongue-flicks, and greater tongue-flick attack score. The clearest differences were observed for tongue-flick attack score, a composite variable that combines the effects of tongue-flicking and biting. An insectivorous member of the same subfamily, Scincella lateralis, shows strong tongue-flicking and biting response to chemical prey cues, but not to plant chemicals. This suggests that response to plant chemicals by C. zebrata may have evolved in tandem with the incorporation of plants into the diet and that response to cricket chemicals has been retained, perhaps due to similarities between plant and animal food. The findings support the hypothesis that dietary shifts induce corresponding changes in chemosensory response, but provide only a single independent contrast for a study of correlated evolution between plant diet and chemosensory response to plants. J. Exp. Zool. 286:372-378, 2000. PMID:10684560

  14. Preparation of Monoclonal Antibody Against Bt Cry1Ac by Using Synthetic Peptide as Hapten%用人工合成多肽作为半抗原制备Bt Cry1Ac的单克隆抗体

    Institute of Scientific and Technical Information of China (English)

    胡小元; 张岐蜀; 段伟; 姜国华; 李玲

    2012-01-01

    为了制备Bt Cry1Ac特异性单克隆抗体(MAB),本试验从NCBI获得了Bt Cry1Ac蛋白的氨基酸序列,根据抗原性、亲水性和表位性分析选定Bt Cry1Ac特异性肽段进行人工合成,并将其偶联于匙孔血蓝蛋白(KLH)免疫动物,应用细胞融合技术制备了抗该肽段的杂交瘤细胞34株.通过ELISA和免疫印迹试验从中筛选出与Bt Cry1Ac天然蛋白产生特异性反应的单克隆抗体杂交瘤细胞株一株(6G9).ELISA和免疫印迹试验结果显示,该克隆株所分泌的MAB能对合成肽和Bt Cry1Ac产生特异性反应,而与同源的Bt Cry1Aa、Bt Cry1Ab天然蛋白均无交叉反应.通过对转基因棉花的ELISA检测结果表明,本试验所制备的Bt Cry1Ac单克隆抗体能够有效的区分常规棉和抗虫棉,并且能对其中的Bt Cry1Ac蛋白进行特异性的识别.%order to prepare monoclonal antibody Bt CrylAc, we got the amino acid sequence of Bt CrylAc protein from NCBI, and synthesized specific Bt CrylAc peptide, according to its antigenicity, hydro-philicity and accessibility on the basis of its structural features by computer assisted analysis. The peptide was linked with carrier keyhole limpet hemocyanin( KHL), and then used for immunized mouse as antigen. 34 strains of hybridoma, which can produce monoclonal antibodies to the peptide, have been obtained by cell fusion technique. One hybridoma strain (6G9), which was specific to natural Bt Cryl Ac was selected by indirect ELISA and Western blot. The result showed that the monoclonal antibody of hybridoma strain (6G9) can react specifically with the synthetic peptide and Bt CrylAc protein, but can not react with Bt CrylAa and Bt Cryl Ab proteins by ELISA and Western blot. This result of experiment showed that the monoclonal antibody of hybridoma strain(6C9)can distinguish transgenic Bt CrylAc cotton and general cotton by ELISA, and it can recognize specifically Bt CrylAc protein in cotton.

  15. Pyrrolizidine Alkaloids Negatively Affect a Generalist Herbivore Feeding on the Chemically Protected Legume Crotalaria pallida.

    Science.gov (United States)

    Cogni, R; Trigo, J R

    2016-06-01

    Plant secondary metabolites can have opposing effects on adapted specialist and non-adapted, generalist herbivores. In this study, we used Heliothis virescens (Fabricius) (Lepidoptera: Noctuidae) as a generalist, non-adapted model herbivore to test the possible effects of Crotalaria pallida (Fabaceae: Papilionoideae) defenses on herbivore performance. Neonate H. virescens larvae were able to consume C. pallida leaves and fruits and grow for a few instars, but none of them survived to pupation. We added isolated pyrrolizidine alkaloids (PAs) to an artificial diet at different concentrations, and PA concentration significantly affected the number of larvae that achieved pupation. Larval survival was not reduced at a PA concentration similar to the concentration on green seeds of C. pallida, but it was significantly reduced at PA concentration 5 and 100 times higher. These results suggest that PAs in isolation are not the defense responsible for the mortality in fresh C. pallida plants, indicating the importance of other possible defenses. The negative effect of PAs on fitness of the non-adapted, generalist herbivore is in agreement with few previous studies, but it is in clear contrast to a previous study on the effects of PAs on the adapted specialist herbivore Utetheisa ornatrix (L.) that were able to sequester PAs with no fitness costs. PMID:26830432

  16. 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

  17. Genetic Variation of the Host Plant Species Matters for Interactions with Above- and Belowground Herbivores

    Directory of Open Access Journals (Sweden)

    Dinesh Kafle

    2014-08-01

    Full Text Available Plants are challenged by both above- and belowground herbivores which may indirectly interact with each other via herbivore-induced changes in plant traits; however, little is known about how genetic variation of the host plant shapes such interactions. We used two genotypes (M4 and E9 of Solanum dulcamara (Solanaceae with or without previous experience of aboveground herbivory by Spodoptera exigua (Noctuidae to quantify its effects on subsequent root herbivory by Agriotes spp. (Elateridae. In the genotype M4, due to the aboveground herbivory, shoot and root biomass was significantly decreased, roots had a lower C/N ratio and contained significantly higher levels of proteins, while the genotype E9 was not affected. However, aboveground herbivory had no effects on weight gain or mortality of the belowground herbivores. Root herbivory by Agriotes increased the nitrogen concentration in the roots of M4 plants leading to a higher weight gain of conspecific larvae. Also, in feeding bioassays, Agriotes larvae tended to prefer roots of M4 over E9, irrespective of the aboveground herbivore treatment. Fourier-Transform Infrared Spectroscopy (FT-IR documented differences in metabolic profiles of the two plant genotypes and of the roots of M4 plants after aboveground herbivory. Together, these results demonstrate that previous aboveground herbivory can have genotype-specific effects on quantitative and qualitative root traits. This may have consequences for belowground interactions, although generalist root herbivores might not be affected when the root biomass offered is still sufficient for growth and survival.

  18. Avoiding incidental predation by mammalian herbivores: accurate detection and efficient response in aphids

    Science.gov (United States)

    Gish, Moshe; Dafni, Amots; Inbar, Moshe

    2011-09-01

    Mammalian herbivores eat plants that may also provide food and shelter for insects. The direct trophic effect of the browsing and grazing of mammalian herbivory on insects, which is probably prevalent in terrestrial ecosystems, has been mostly neglected by ecologists. We examined how the aphid Uroleucon sonchi L. deals with the danger of incidental predation by mammalian herbivores. We found that most (76%) of the aphids in a colony survive the ingestion of the plant by a feeding herbivore. They do so by sensing the combination of heat and humidity in the herbivore's breath and immediately dropping off the plant in large numbers. Their ability to sense the herbivore's breath or their tendency to drop off the plant weakens as ambient temperature rises. This could indicate a limitation of the aphids' sensory system or an adaptation that enables them to avoid the hostile conditions on a hot ground. Once on the ground, U. sonchi is highly mobile and capable of locating a new host plant by advancing in a pattern that differs significantly from random movement. The accurate and efficient defense mechanism of U. sonchi emphasizes the significance of incidental predation as a danger to plant-dwelling invertebrates.

  19. Microbial detoxification in the gut of a specialist avian herbivore, the Greater Sage-Grouse.

    Science.gov (United States)

    Kohl, Kevin D; Connelly, John W; Dearing, M Denise; Forbey, Jennifer Sorensen

    2016-07-01

    One function of the gut microbiota gaining recent attention, especially in herbivorous mammals and insects, is the metabolism of plant secondary metabolites (PSMs). We investigated whether this function exists within the gut communities of a specialist avian herbivore. We sequenced the cecal metagenome of the Greater Sage-Grouse (Centrocercus urophasianus), which specializes on chemically defended sagebrush (Artemisia spp.). We predicted that the cecal metagenome of the sage-grouse would be enriched in genes associated with the metabolism of PSMs when compared to the metagenome of the domestic chicken. We found that representation of microbial genes associated with 'xenobiotic degradation and metabolism' was 3-fold higher in the sage-grouse cecal metagenomes when compared to that of the domestic chicken. Further, we identified a complete metabolic pathway for the degradation of phenol to pyruvate, which was not detected in the metagenomes of the domestic chicken, bovine rumen or 14 species of mammalian herbivores. Evidence of monoterpene degradation (a major class of PSMs in sagebrush) was less definitive, although we did detect genes for several enzymes associated with this process. Overall, our results suggest that the gut microbiota of specialist avian herbivores plays a similar role to the microbiota of mammalian and insect herbivores in degrading PSMs. PMID:27242374

  20. Herbivores modify selection on plant functional traits in a temperate rainforest understory.

    Science.gov (United States)

    Salgado-Luarte, Cristian; Gianoli, Ernesto

    2012-08-01

    There is limited evidence regarding the adaptive value of plant functional traits in contrasting light environments. It has been suggested that changes in these traits in response to light availability can increase herbivore susceptibility. We tested the adaptive value of plant functional traits linked with carbon gain in contrasting light environments and also evaluated whether herbivores can modify selection on these traits in each light environment. In a temperate rainforest, we examined phenotypic selection on functional traits in seedlings of the pioneer tree Aristotelia chilensis growing in sun (canopy gap) and shade (forest understory) and subjected to either natural herbivory or herbivore exclusion. We found differential selection on functional traits depending on light environment. In sun, there was positive directional selection on photosynthetic rate and relative growth rate (RGR), indicating that selection favors competitive ability in a high-resource environment. Seedlings with high specific leaf area (SLA) and intermediate RGR were selected in shade, suggesting that light capture and conservative resource use are favored in the understory. Herbivores reduced the strength of positive directional selection acting on SLA in shade. We provide the first demonstration that natural herbivory rates can change the strength of selection on plant ecophysiological traits, that is, attributes whose main function is resource uptake. Research addressing the evolution of shade tolerance should incorporate the selective role of herbivores. PMID:22766937

  1. Effects of the removal of large herbivores on fleas of small mammals.

    Science.gov (United States)

    McCauley, Douglas J; Keesing, Felicia; Young, Truman; Dittmar, Katharina

    2008-12-01

    The removal of large herbivorous mammals can cause dramatic increases in the densities of small mammals. These small mammals are hosts for a variety of ectoparasites, many of which are important pathogens of human diseases such as plague and murine typhus. It is thus valuable from a human health perspective to understand if large herbivore removals can indirectly affect ectoparasite numbers and thus potentially alter disease risk. To make this determination, we experimentally excluded large herbivores and measured the number of fleas present on the numerically dominant small mammal, the pouched mouse, Saccostomus mearnsi. Removing large herbivores nearly doubled S. mearnsi density, while the percentage of mice infested with fleas (prevalence) and the average number of fleas per sampled mouse (intensity) remained constant. The net effect of doubling the number of mice via the removal of large herbivores was a near doubling in the number of fleas present in the study habitat. Because these fleas also parasitize humans and can serve as disease vectors, this work empirically demonstrates a potential mechanism by which ecosystem alterations could affect human risk for zoonotic diseases. PMID:19263845

  2. Scientific Opinion supplementing the conclusions of the environmental risk assessment and risk management recommendations for the cultivation of the genetically modified insect resistant maize Bt11 and MON 810

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Genetically Modified Organisms (GMO

    2012-12-01

    Full Text Available The EFSA GMO Panel was asked by the European Commission to apply its mathematical model to simulate and assess potential adverse effects resulting from the exposure of non-target Lepidoptera to maize Bt11 or MON 810 pollen under hypothetical agricultural conditions, and to provide information on the factors affecting the insect resistance management plan, additional to that in its 2011 Statement supplementing the evaluation of the environmental risk assessment and risk management recommendations on insect resistant genetically modified maize Bt11 for cultivation. Here, risk managers are provided with additional evidence and further clarifications to those previous conclusions and risk management recommendations. This Scientific Opinion provides background scientific information to inform the decision-making process; the EFSA GMO Panel reiterates that risk managers should choose risk mitigation and management measures that are proportionate to the level of identified risk according to the protection goals pertaining to their regions.

  3. Influence of one or two Bt genes transgenic cotton free living nitrogen fixers and p-solubilising microorganisms in vertisols and alfisols

    Science.gov (United States)

    Sudha, T.; Babu, R.; Biradar, D. P.; Patil, V. C.; Shirnalli, G.

    2012-04-01

    India, the largest cotton grower in the world benefited from the cultivation of genetically modified Bt transgenic cotton. Bt cotton with the single gene (cry 1Ac) contributed to increased productivity over the last eight years. But in the recent years, there has been an increasing trend to adopt two genes (cry 1Ac and cry 2Ab) transgenic cotton in India. The two gene Bt cotton hybrids were planted over a large area (57%) during 2009 than the single gene Bt cotton hybrids. In this context, the field experiments were conducted in farmers field in both Vertisols and Alfisols during monsoon season of 2009 to study the effect of a single gene Bt hybrid (RCH-2Bt, JK-99Bt, Mallika Bt, MRC-6918 Bt, Brahma Bt, RCH-708 Bt, Bunny Bt) as well as two gene Bt hybrids (RCH-2 BGII Bt, Bunny BGII Bt) compared with the non genetically modified (non-Bt) hybrid (DHH-11) on the population of free living nitrogen fixing microorganisms (Azospirillum and methylotrophs) and P-solubilizers in two different soil types under rainfed situation. Observations on microbial population were recorded at flowering and at harvest in both the soil types. Results indicated a higher population of Azospirillum, methylotrophs and P-solubilisers in the rhizosphere grown with single or two gene Bt hybrid and non-Bt hybrid at flowering stage in both the soil types. In Vertisol, significantly higher population of methylotrophs in MRC-6918 Bt (30 x 102/g of soil), P-solubilizers in RCH-2 Bt (31x103/g of soil) and Azospirillum in RCH-708 Bt (0.79 x 106 /g of soil) was recorded as compared to non-Bt hybrid DHH-11 (2 x 102/g of soil, 12 x 103/g of soil, 0.54 x 106/g of soil), respectively. Whereas, in Alfisol, significantly higher population of methylotrophs in RCH-2 Bt (13x 102/g of soil), P-solubilisers in JK-99 Bt (38 x 103/g of soil) and Azospirillum in RCH-2Bt (0.57 x 106/g of soil) was recorded over non Bt hybrid DHH-11 (2x 102/g of soil, 13x 103/g of soil and 0.17 x106/g of soil) respectively. Our results

  4. Is the Cry1Ab protein from Bacillus thuringiensis (Bt) taken up by plants from soils previously planted with Bt corn and by carrot from hydroponic culture?

    Science.gov (United States)

    Icoz, I; Andow, D; Zwahlen, C; Stotzky, G

    2009-07-01

    The uptake of the insecticidal Cry1Ab protein from Bacillus thuringiensis (Bt) by various crops from soils on which Bt corn had previously grown was determined. In 2005, the Cry1Ab protein was detected by Western blot in tissues (leaves plus stems) of basil, carrot, kale, lettuce, okra, parsnip, radish, snap bean, and soybean but not in tissues of beet and spinach and was estimated by enzyme-linked immunosorbent assay (ELISA) to be 0.05 +/- 0.003 ng g(-1) of fresh plant tissue in basil, 0.02 +/- 0.014 ng g(-1) in okra, and 0.34 +/- 0.176 ng g(-1) in snap bean. However, the protein was not detected by ELISA in carrot, kale, lettuce, parsnip, radish, and soybean or in the soils by Western blot. In 2006, the Cry1Ab protein was detected by Western blot in tissues of basil, carrot, kale, radish, snap bean, and soybean from soils on which Bt corn had been grown the previous year and was estimated by ELISA to be 0.02 +/- 0.014 ng g(-1) of fresh plant tissue in basil, 0.19 +/- 0.060 ng g(-1) in carrot, 0.05 +/- 0.018 ng g(-1) in kale, 0.04 +/- 0.022 ng g(-1) in radish, 0.53 +/- 0.170 ng g(-1) in snap bean, and 0.15 +/- 0.071 ng g(-1) in soybean. The Cry1Ab protein was also detected by Western blot in tissues of basil, carrot, kale, radish, and snap bean but not of soybean grown in soil on which Bt corn had not been grown since 2002; the concentration was estimated by ELISA to be 0.03 +/- 0.021 ng g(-1) in basil, 0.02 +/- 0.008 ng g(-1) in carrot, 0.04 +/- 0.017 ng g(-1) in kale, 0.02 +/- 0.012 ng g(-1) in radish, 0.05 +/- 0.004 ng g(-1) in snap bean, and 0.09 +/- 0.015 ng g(-1) in soybean. The protein was detected by Western blot in 2006 in most soils on which Bt corn had or had not been grown since 2002. The Cry1Ab protein was detected by Western blot in leaves plus stems and in roots of carrot after 56 days of growth in sterile hydroponic culture to which purified Cry1Ab protein had been added and was estimated by ELISA to be 0.08 +/- 0.021 and 0.60 +/- 0.148 ng g(-1) of

  5. Positive and negative effects of grass, cattle, and wild herbivores on Acacia saplings in an East African savanna.

    Science.gov (United States)

    Riginos, Corinna; Young, Truman P

    2007-10-01

    Plant-plant interactions can be a complex mixture of positive and negative interactions, with the net outcome depending on abiotic and community contexts. In savanna systems, the effects of large herbivores on tree-grass interactions have rarely been studied experimentally, though these herbivores are major players in these systems. In African savannas, trees often become more abundant under heavy cattle grazing but less abundant in wildlife preserves. Woody encroachment where cattle have replaced wild herbivores may be caused by a shift in the competitive balance between trees and grasses. Here we report the results of an experiment designed to quantify the positive, negative, and net effects of grasses, wild herbivores, and cattle on Acacia saplings in a Kenyan savanna. Acacia drepanolobium saplings under four long-term herbivore regimes (wild herbivores, cattle, cattle + wild herbivores, and no large herbivores) were cleared of surrounding grass or left with the surrounding grass intact. After two years, grass-removal saplings exhibited 86% more browse damage than control saplings, suggesting that grass benefited saplings by protecting them from herbivory. However, the negative effect of grass on saplings was far greater; grass-removal trees accrued more than twice the total stem length of control trees. Where wild herbivores were present, saplings were browsed more and produced more new stem growth. Thus, the net effect of wild herbivores was positive, possibly due to the indirect effects of lower competitor tree density in areas accessible to elephants. Additionally, colonization of saplings by symbiotic ants tracked growth patterns, and colonized saplings experienced lower rates of browse damage. These results suggest that savanna tree growth and woody encroachment cannot be predicted by grass cover or herbivore type alone. Rather, tree growth appears to depend on a variety of factors that may be acting together or antagonistically at different stages of the

  6. The Nutritional Balancing Act of a Large Herbivore: An Experiment with Captive Moose (Alces alces L).

    Science.gov (United States)

    Felton, Annika M; Felton, Adam; Raubenheimer, David; Simpson, Stephen J; Krizsan, Sophie J; Hedwall, Per-Ola; Stolter, Caroline

    2016-01-01

    The nutrient balancing hypothesis proposes that, when sufficient food is available, the primary goal of animal diet selection is to obtain a nutritionally balanced diet. This hypothesis can be tested using the Geometric Framework for nutrition (GF). The GF enables researchers to study patterns of nutrient intake (e.g. macronutrients; protein, carbohydrates, fat), interactions between the different nutrients, and how an animal resolves the potential conflict between over-eating one or more nutrients and under-eating others during periods of dietary imbalance. Using the moose (Alces alces L.), a model species in the development of herbivore foraging theory, we conducted a feeding experiment guided by the GF, combining continuous observations of six captive moose with analysis of the macronutritional composition of foods. We identified the moose's self-selected macronutrient target by allowing them to compose a diet by mixing two nutritionally complementary pellet types plus limited access to Salix browse. Such periods of free choice were intermixed with periods when they were restricted to one of the two pellet types plus Salix browse. Our observations of food intake by moose given free choice lend support to the nutrient balancing hypothesis, as the moose combined the foods in specific proportions that provided a particular ratio and amount of macronutrients. When restricted to either of two diets comprising a single pellet type, the moose i) maintained a relatively stable intake of non-protein energy while allowing protein intakes to vary with food composition, and ii) increased their intake of the food item that most closely resembled the self-selected macronutrient intake from the free choice periods, namely Salix browse. We place our results in the context of the nutritional strategy of the moose, ruminant physiology and the categorization of food quality. PMID:26986618

  7. The Nutritional Balancing Act of a Large Herbivore: An Experiment with Captive Moose (Alces alces L.

    Directory of Open Access Journals (Sweden)

    Annika M Felton

    Full Text Available The nutrient balancing hypothesis proposes that, when sufficient food is available, the primary goal of animal diet selection is to obtain a nutritionally balanced diet. This hypothesis can be tested using the Geometric Framework for nutrition (GF. The GF enables researchers to study patterns of nutrient intake (e.g. macronutrients; protein, carbohydrates, fat, interactions between the different nutrients, and how an animal resolves the potential conflict between over-eating one or more nutrients and under-eating others during periods of dietary imbalance. Using the moose (Alces alces L., a model species in the development of herbivore foraging theory, we conducted a feeding experiment guided by the GF, combining continuous observations of six captive moose with analysis of the macronutritional composition of foods. We identified the moose's self-selected macronutrient target by allowing them to compose a diet by mixing two nutritionally complementary pellet types plus limited access to Salix browse. Such periods of free choice were intermixed with periods when they were restricted to one of the two pellet types plus Salix browse. Our observations of food intake by moose given free choice lend support to the nutrient balancing hypothesis, as the moose combined the foods in specific proportions that provided a particular ratio and amount of macronutrients. When restricted to either of two diets comprising a single pellet type, the moose i maintained a relatively stable intake of non-protein energy while allowing protein intakes to vary with food composition, and ii increased their intake of the food item that most closely resembled the self-selected macronutrient intake from the free choice periods, namely Salix browse. We place our results in the context of the nutritional strategy of the moose, ruminant physiology and the categorization of food quality.

  8. Study on kinetic degradation in soil and horizontal transfer of bt gene by 35S isotopic tracing method

    International Nuclear Information System (INIS)

    In this study, 35S isotopic tracing method was applied to investigate kinetic degradation of bt gene from Bt transgenic rice TT51 in two different soil and possibility of its horizontal transfer into soil bacteria as well. Results showed that, during 30 d of aerobic incubation, it was indicated that 35S-Bt gene was not horizontally transferred into soil microorganisms. The aerobic soil degradation dynamics significantly followed a first-order dissipation pattern for bt gene. After 30 d of incubation, the amount of bt gene reached 9.32% of applied radioactivity for the fluvio-marine yellow loamy soil and 9.92% for the fluvio-aquatic soil, respectively. The half-lives in two soils were 3.53 d for the former soil and 5. 77 d for the latter soil, which means that bt gene was more easily degradable in the weak acidic soil. The use of 35S labeling proved to be valuable; it served the purpose of validating the rigorousness of experimental protocols, and provided insights into the soil environmental safety assessment for Bt transgenic rice. (authors)

  9. Effect of Transgenic Bt Cotton on Abundance of Cotton Spider Mites and Total Phenolic Content of Leaves and their Relationship

    Directory of Open Access Journals (Sweden)

    Yanfang Pei

    2012-12-01

    Full Text Available The differences of the total phenolic content in leaves and percentage of cotton plants infested with cotton spider mites between in transgenic Bt (Ezamian No. 24F1 and in non-transgenic Bt cotton (Ek 9 parental line of Ezamian No. 24F1 plots with and without spraying acaricides were systematically investigated in Tai Lake farm, Hubei Province, China, over the period 26 May and 11 September 2011. In acaricide treated plots, transgenic Bt cotton does not result in a change of the abundance of cotton spider mites compared to that in non-transgenic Bt cotton, however, without acaricide treated plots, transgenic Bt cotton significantly increases the abundance of cotton spider mites compared to those of non-transgenic Bt cotton. The number of eggs, larva-nymph-adults, egg-larvanymph- adults and the plant damage index are independent of the total phenolic content in leaves. The results are also discussed in relation to integrated pest management. It was very necessary for nontarget cotton spider mites of transgenic Bt cotton fields to control in wetland agricultural area.

  10. Impact of Bt corn on rhizospheric and soil eubacterial communities and on beneficial mycorrhizal symbiosis in experimental microcosms.

    Science.gov (United States)

    Castaldini, M; Turrini, A; Sbrana, C; Benedetti, A; Marchionni, M; Mocali, S; Fabiani, A; Landi, S; Santomassimo, F; Pietrangeli, B; Nuti, M P; Miclaus, N; Giovannetti, M

    2005-11-01

    A polyphasic approach has been developed to gain knowledge of suitable key indicators for the evaluation of environmental impact of genetically modified Bt 11 and Bt 176 corn lines on soil ecosystems. We assessed the effects of Bt corn (which constitutively expresses the insecticidal toxin from Bacillus thuringiensis, encoded by the truncated Cry1Ab gene) and non-Bt corn plants and their residues on rhizospheric and bulk soil eubacterial communities by means of denaturing gradient gel electrophoresis analyses of 16S rRNA genes, on the nontarget mycorrhizal symbiont Glomus mosseae, and on soil respiration. Microcosm experiments showed differences in rhizospheric eubacterial communities associated with the three corn lines and a significantly lower level of mycorrhizal colonization in Bt 176 corn roots. In greenhouse experiments, differences between Bt and non-Bt corn plants were detected in rhizospheric eubacterial communities (both total and active), in culturable rhizospheric heterotrophic bacteria, and in mycorrhizal colonization. Plant residues of transgenic plants, plowed under at harvest and kept mixed with soil for up to 4 months, affected soil respiration, bacterial communities, and mycorrhizal establishment by indigenous endophytes. The multimodal approach utilized in our work may be applied in long-term field studies aimed at monitoring the real hazard of genetically modified crops and their residues on nontarget soil microbial communities. PMID:16269702

  11. Progress of the BT-EdF-CEA project. The lithium polymer battery; Avancees du projet BT-EdF-CEA. Batterie lithium polymere

    Energy Technology Data Exchange (ETDEWEB)

    Marginedes, D.; Majastre, H. [Bollore Technologies, 29 - Quimper (France); Baudry, P.; Lascaud, S. [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches; Bloch, D.; Lebrun, N. [CEA Grenoble, CEREM, 38 (France)

    1996-12-31

    The lithium-polymer energy storage technology requires the production of thin films of huge surface. The BT-EdF-CEA consortium has studied the various manufacturing techniques of these films and their assembly. The process was chosen according to its productivity, low expensiveness, ecological impact and energy performances with capacities reaching 40 Ah. This paper explains: the objectives and specifications of the project, the advantage of the consortium and the role of the different partners, the results (coating, dry extrusion and battery element manufacturing techniques), and the electrochemical performances of the elements. (J.S.)

  12. Effect of insertion of Bt gene in corn and different fumonisin content on growth performance of weaned piglets

    Directory of Open Access Journals (Sweden)

    Filippo Rossi

    2010-05-01

    Full Text Available The objective of this study was to compare the effect of Bt corn and isogenic corn on the growth of weaned piglets. One hundred and twenty-eight weaned piglets weighing 8.8±1.27 kg live weight were randomly assigned to 4 groups of 32 animals each (16 castrated males and 16 females. Bt corn (line MON810 and isogenic corn were produced at two farms located in the provinces of Lodi and Venice (northern Italy. The Bt corn had the same chemical composition as the isogenic corn but a lower content of fumonisin B1 (FB1. The experimental period (35 days was in 2 phases, 0-14 d and 15-35 d. There was no significant difference in average daily gain (ADG among groups during the first feeding phase. Compared to animals fed isogenic corn, the piglets fed Bt maize gained more weight during the second feeding phase (Bt: 464.1 g/d, isogenic: 429.1 g/d; P<0.05. Also, the ADG over the entire trial was higher in piglets fed Bt corn versus piglets fed isogenic corn (Bt: 396.4 g/d, isogenic: 374.1 g/d; P<0.05. The ADG of the whole period decreased linearly (P<0.05 with respect to the FB1 content of the diet. Final weight was higher in piglets fed the diet containing Bt corn (Bt: 22.68 kg, isogenic: 21.83 kg; P<0.05. No differences in feed intake and in the feed:gain ratio were observed, although a linear response between FB1 and feed:gain ratio in first 14 days of the experiment was detected.

  13. Effect of insertion of Bt gene in corn and different fumonisin content on growth performance of weaned piglets

    Directory of Open Access Journals (Sweden)

    Filippo Rossi

    2011-04-01

    Full Text Available The objective of this study was to compare the effect of Bt corn and isogenic corn on the growth of weaned piglets. One hundred twenty-eight weaned piglets weighing 8.8 ±1.27 kg live weight were randomly assigned to 4 groups of 32 animals each (16 castrated males and 16 females. Bt corn (line MON810 and isogenic corn were produced at two farms located in the Lodi and Venezia provinces (northern Italy. Bt corn had the same chemical composition as the isogenic corn but a lower content of fumonisin B1 (FB1. The experimental period (35 days was divided into two phases: 0-14 d and 15-35 d. There was no significant difference in average daily gain (ADG among groups during the first feeding phase. Compared to animals fed isogenic corn, the piglets fed Bt maize gained more weight during the second feeding phase (Bt: 464.1 g/d, isogenic: 429.1 g/d; P < 0.05. Also, the ADG over the entire trial was higher in piglets fed Bt corn versus piglets fed isogenic corn (Bt: 396.4 g/d, isogenic: 374.1 g/d; P < 0.05. The ADG of the whole period decreased linearly (P<0.05 with respect to FB1 content of diet. Final weight was higher in piglets fed the diet containing Bt corn (Bt: 22.68 kg, isogenic: 21.83 kg; P < 0.05. No differences in feed intake and in the feed:gain ratio were observed, however a linear response between FB1 and feed:gain ratio in first 14 days of the experiment was detected.

  14. Benefits of jasmonate-dependent defenses against vertebrate herbivores in nature.

    Science.gov (United States)

    Machado, Ricardo Ar; McClure, Mark; Hervé, Maxime R; Baldwin, Ian T; Erb, Matthias

    2016-01-01

    Endogenous jasmonates are important regulators of plant defenses. If and how they enable plants to maintain their reproductive output when facing community-level herbivory under natural conditions, however, remains unknown. We demonstrate that jasmonate-deficient Nicotiana attenuata plants suffer more damage by arthropod and vertebrate herbivores than jasmonate-producing plants in nature. However, only damage by vertebrate herbivores translates into a significant reduction in flower production. Vertebrate stem peeling has the strongest negative impact on plant flower production. Stems are defended by jasmonate-dependent nicotine, and the native cottontail rabbit Sylvilagus nuttallii avoids jasmonate-producing N. attenuata shoots because of their high levels of nicotine. Thus, endogenous jasmonates enable plants to resist different types of herbivores in nature, and jasmonate-dependent defenses are important for plants to maintain their reproductive potential when facing vertebrate herbivory. Ecological and evolutionary models on plant defense signaling should aim at integrating arthropod and vertebrate herbivory at the community level. PMID:27352734

  15. Non-Host Plant Volatiles Disrupt Sex Pheromone Communication in a Specialist Herbivore.

    Science.gov (United States)

    Wang, Fumin; Deng, Jianyu; Schal, Coby; Lou, Yonggen; Zhou, Guoxin; Ye, Bingbing; Yin, Xiaohui; Xu, Zhihong; Shen, Lize

    2016-01-01

    The ecological effects of plant volatiles on herbivores are manifold. Little is known, however, about the impacts of non-host plant volatiles on intersexual pheromonal communication in specialist herbivores. We tested the effects of several prominent constitutive terpenoids released by conifers and Eucalyptus trees on electrophysiological and behavioral responses of an oligophagous species, Plutella xylostella, which feeds on Brassicaceae. The non-host plant volatile terpenoids adversely affected the calling behavior (pheromone emission) of adult females, and the orientation responses of adult males to sex pheromone were also significantly inhibited by these terpenoids in a wind tunnel and in the field. We suggest that disruption of both pheromone emission and orientation to sex pheromone may explain, at least in part, an observed reduction in herbivore attack in polyculture compared with monoculture plantings. We also propose that mating disruption of both male and female moths with non-host plant volatiles may be a promising alternative pest management strategy. PMID:27585907

  16. Increase in toxicity of an invasive weed after reassociation with its coevolved herbivore.

    Science.gov (United States)

    Zangerl, Arthur R; Berenbaum, May R

    2005-10-25

    The ability of weeds to proliferate into nonindigenous habitats has been attributed to escape from their native natural enemies, allowing reallocation of resources from chemical defense into growth and reproduction. Many invasive weeds, however, eventually encounter their native, coevolved enemies in areas of introduction. Examination of herbarium specimens of an invasive phototoxic European weed, Pastinaca sativa, through 152 years reveals phytochemical shifts coincident in time with the accidental introduction of a major herbivore, the parsnip webworm, Depressaria pastinacella. Plants collected before the introduction of webworms in North America and during the earliest stages of establishment (1850-1889) are lower in toxic furanocoumarins than all plants subsequently collected in North America and lower than European plant samples collected before 1889. Thus, introduction of a major specialist herbivore can increase noxiousness of a species in its area of introduction, illuminating a potential consequence of classical biocontrol programs involving insect herbivores and poisonous weeds. PMID:16230607

  17. The influence of a neotropical herbivore (Lamponius portoricensis) on nutrient cycling and soil processes.

    Science.gov (United States)

    Fonte, S J; Schowalter, T D

    2005-12-01

    The role of phytophagous insects in ecosystem nutrient cycling remains poorly understood. By altering the flow of litterfall nutrients from the canopy to the forest floor, herbivores may influence key ecosystem processes. We manipulated levels of herbivory in a lower montane tropical rainforest of Puerto Rico using the common herbivore, Lamponius portoricensis (Phasmatidea), on a prevalent understory plant, Piper glabrescens (Piperaceae), and measured the effects on nutrient input to the forest floor and on rates of litter decomposition. Four treatment levels of herbivory generated a full range of leaf area removal, from plants experiencing no herbivory to plants that were completely defoliated (>4,000 cm(2) leaf area removed during the 76-day study duration). A significant (Pfloor. These results suggest that insect herbivores can influence forest floor nutrient dynamics and thus merit further consideration in discussions on ecosystem nutrient dynamics. PMID:16175388

  18. Effect of Nitrogen Fertilizer on Herbivores and Its Stimulation to Major Insect Pests in Rice

    Institute of Scientific and Technical Information of China (English)

    LU Zhong-xian; YU Xiao-ping; Kong-luen HEONG; HU Cui

    2007-01-01

    Nitrogen is one of the most important factors in development of herbivore populations. The application of nitrogen fertilizer in plants can normally increase herbivore feeding preference, food consumption, survival, growth, reproduction, and population density, except few examples that nitrogen fertilizer reduces the herbivore performances. In most of the rice growing areas in Asia, the great increases in populations of major insect pests of rice, including planthoppers (Nilaparvata lugens and Sogatella furcifera), leaffolder (Cnaphalocrocis medinalis), and stem borers (Scirpophaga incertulas, Chilo suppressalis, S. innotata, C. polychrysus and Sesamia inferens) were closely related to the long-term excessive application of nitrogen fertilizers. The optimal regime of nitrogen fertilizer in irrigated paddy fields is proposed to improve the fertilizer-nitrogen use efficiency and reduce the environmental pollution.

  19. Effect of insertion of Bt gene in corn and different fumonisin content on growth performance of weaned piglets

    OpenAIRE

    Filippo Rossi; Mauro Morlacchini; Giorgio Fusconi; Amedeo Pietri; Gianfranco Piva

    2011-01-01

    The objective of this study was to compare the effect of Bt corn and isogenic corn on the growth of weaned piglets. One hundred twenty-eight weaned piglets weighing 8.8 ±1.27 kg live weight were randomly assigned to 4 groups of 32 animals each (16 castrated males and 16 females). Bt corn (line MON810) and isogenic corn were produced at two farms located in the Lodi and Venezia provinces (northern Italy). Bt corn had the same chemical composition as the isogenic corn but a lower content...

  20. Oak-insect herbivore interactions along a temperature and precipitation gradient

    Science.gov (United States)

    Leckey, Erin H.; Smith, Dena M.; Nufio, César R.; Fornash, Katherine F.

    2014-11-01

    The interactions between herbivorous insects and their host plants are expected to be influenced by changing climates. Modern oaks provide an excellent system to examine this assumption because their interactions with herbivores occur over broad climatic and spatial scales, they vary in their defensive and nutritional investment in leaves by being deciduous or evergreen, and their insect herbivores range from generalists to highly specialized feeders. In this study, we surveyed leaf-litter samples of four oak species along an elevation gradient, from coastal northern California, USA, to the upper montane woodlands of the Sierra Nevada, to examine the relationship between climatic factors (mean annual temperature and precipitation) and oak herbivory levels at multiple scales; across all oak species pooled, between evergreen and deciduous species and within species. Overall, temperature and precipitation did not appear to have a significant effect on most measures of total herbivore damage (percent leaves damaged per tree, percent leaf area removed and average number of feeding damage marks per leaf) and the strongest predictor of herbivore damage overall was the identity of the host species. However, increases in precipitation were correlated with an increase in the actual leaf area removed, and specialized insects, such as those that make leaf mines and galls, were the most sensitive to differences in precipitation levels. This suggests that the effects of changing climate on some plant-insect interactions is less likely to result in broad scale increases in damage with increasing temperatures or changing precipitation levels, but is rather more likely to be dependent on the type of herbivore (specialist vs. generalist) and the scale (species vs. community) over which the effect is examined.

  1. Hyperparasitoids use herbivore-induced plant volatiles to locate their parasitoid host.

    Science.gov (United States)

    Poelman, Erik H; Bruinsma, Maaike; Zhu, Feng; Weldegergis, Berhane T; Boursault, Aline E; Jongema, Yde; van Loon, Joop J A; Vet, Louise E M; Harvey, Jeffrey A; Dicke, Marcel

    2012-01-01

    Plants respond to herbivory with the emission of induced plant volatiles. These volatiles may attract parasitic wasps (parasitoids) that attack the herbivores. Although in this sense the emission of volatiles has been hypothesized to be beneficial to the plant, it is still debated whether this is also the case under natural conditions because other organisms such as herbivores also respond to the emitted volatiles. One important group of organisms, the enemies of parasitoids, hyperparasitoids, has not been included in this debate because little is known about their foraging behaviour. Here, we address whether hyperparasitoids use herbivore-induced plant volatiles to locate their host. We show that hyperparasitoids find their victims through herbivore-induced plant volatiles emitted in response to attack by caterpillars that in turn had been parasitized by primary parasitoids. Moreover, only one of two species of parasitoids affected herbivore-induced plant volatiles resulting in the attraction of more hyperparasitoids than volatiles from plants damaged by healthy caterpillars. This resulted in higher levels of hyperparasitism of the parasitoid that indirectly gave away its presence through its effect on plant odours induced by its caterpillar host. Here, we provide evidence for a role of compounds in the oral secretion of parasitized caterpillars that induce these changes in plant volatile emission. Our results demonstrate that the effects of herbivore-induced plant volatiles should be placed in a community-wide perspective that includes species in the fourth trophic level to improve our understanding of the ecological functions of volatile release by plants. Furthermore, these findings suggest that the impact of species in the fourth trophic level should also be considered when developing Integrated Pest Management strategies aimed at optimizing the control of insect pests using parasitoids. PMID:23209379

  2. Plant Quantity Affects Development and Survival of a Gregarious Insect Herbivore and Its Endoparasitoid Wasp.

    Science.gov (United States)

    Fei, Minghui; Gols, Rieta; Zhu, Feng; Harvey, Jeffrey A

    2016-01-01

    Virtually all studies of plant-herbivore-natural enemy interactions focus on plant quality as the major constraint on development and survival. However, for many gregarious feeding insect herbivores that feed on small or ephemeral plants, the quantity of resources is much more limiting, yet this area has received virtually no attention. Here, in both lab and semi-field experiments using tents containing variably sized clusters of food plants, we studied the effects of periodic food deprivation in a tri-trophic system where quantitative constraints are profoundly important on insect performance. The large cabbage white Pieris brassicae, is a specialist herbivore of relatively small wild brassicaceous plants that grow in variable densities, with black mustard (Brassica nigra) being one of the most important. Larvae of P. brassicae are in turn attacked by a specialist endoparasitoid wasp, Cotesia glomerata. Increasing the length of food deprivation of newly molted final instar caterpillars significantly decreased herbivore and parasitoid survival and biomass, but shortened their development time. Moreover, the ability of caterpillars to recover when provided with food again was correlated with the length of the food deprivation period. In outdoor tents with natural vegetation, we created conditions similar to those faced by P. brassicae in nature by manipulating plant density. Low densities of B. nigra lead to potential starvation of P. brassicae broods and their parasitoids, replicating nutritional conditions of the lab experiments. The ability of both unparasitized and parasitized caterpillars to find corner plants was similar but decreased with central plant density. Survival of both the herbivore and parasitoid increased with plant density and was higher for unparasitized than for parasitized caterpillars. Our results, in comparison with previous studies, reveal that quantitative constraints are far more important that qualitative constraints on the performance of

  3. Plant Quantity Affects Development and Survival of a Gregarious Insect Herbivore and Its Endoparasitoid Wasp

    Science.gov (United States)

    Fei, Minghui; Gols, Rieta; Zhu, Feng; Harvey, Jeffrey A.

    2016-01-01

    Virtually all studies of plant-herbivore-natural enemy interactions focus on plant quality as the major constraint on development and survival. However, for many gregarious feeding insect herbivores that feed on small or ephemeral plants, the quantity of resources is much more limiting, yet this area has received virtually no attention. Here, in both lab and semi-field experiments using tents containing variably sized clusters of food plants, we studied the effects of periodic food deprivation in a tri-trophic system where quantitative constraints are profoundly important on insect performance. The large cabbage white Pieris brassicae, is a specialist herbivore of relatively small wild brassicaceous plants that grow in variable densities, with black mustard (Brassica nigra) being one of the most important. Larvae of P. brassicae are in turn attacked by a specialist endoparasitoid wasp, Cotesia glomerata. Increasing the length of food deprivation of newly molted final instar caterpillars significantly decreased herbivore and parasitoid survival and biomass, but shortened their development time. Moreover, the ability of caterpillars to recover when provided with food again was correlated with the length of the food deprivation period. In outdoor tents with natural vegetation, we created conditions similar to those faced by P. brassicae in nature by manipulating plant density. Low densities of B. nigra lead to potential starvation of P. brassicae broods and their parasitoids, replicating nutritional conditions of the lab experiments. The ability of both unparasitized and parasitized caterpillars to find corner plants was similar but decreased with central plant density. Survival of both the herbivore and parasitoid increased with plant density and was higher for unparasitized than for parasitized caterpillars. Our results, in comparison with previous studies, reveal that quantitative constraints are far more important that qualitative constraints on the performance of

  4. Reefscapes of fear: predation risk and reef hetero-geneity interact to shape herbivore foraging behaviour.

    Science.gov (United States)

    Catano, Laura B; Rojas, Maria C; Malossi, Ryan J; Peters, Joseph R; Heithaus, Michael R; Fourqurean, James W; Burkepile, Deron E

    2016-01-01

    Predators can exert strong direct and indirect effects on ecological communities by intimidating their prey. The nature of predation risk effects is often context dependent, but in some ecosystems these contingencies are often overlooked. Risk effects are often not uniform across landscapes or among species. Indeed, they can vary widely across gradients of habitat complexity and with different prey escape tactics. These context dependencies may be especially important for ecosystems such as coral reefs that vary widely in habitat complexity and have species-rich predator and prey communities. With field experiments using predator decoys of the black grouper (Mycteroperca bonaci), we investigated how reef complexity interacts with predation risk to affect the foraging behaviour and herbivory rates of large herbivorous fishes (e.g. parrotfishes and surgeonfishes) across four coral reefs in the Florida Keys (USA). In both high and low complexity areas of the reef, we measured how herbivory changed with increasing distance from the predator decoy to examine how herbivorous fishes reconcile the conflicting demands of avoiding predation vs. foraging within a reefscape context. We show that with increasing risk, herbivorous fishes consumed dramatically less food (ca. 90%) but fed at a faster rate when they did feed (ca. 26%). Furthermore, we show that fishes foraging closest to the predator decoy were 40% smaller than those that foraged at further distances. Thus, smaller individuals showed muted response to predation risk compared to their larger counterparts, potentially due to their decreased risk to predation or lower reproductive value (i.e. the asset protection principle). Habitat heterogeneity mediated risk effects differently for different species of herbivores, with predation risk more strongly suppressing herbivore feeding in more complex areas and for individuals at higher risk of predation. Predators appear to create a reefscape of fear that changes the size

  5. Within-population isotopic niche variability in savanna mammals: disparity between carnivores and herbivores

    Directory of Open Access Journals (Sweden)

    Daryl eCodron

    2016-02-01

    Full Text Available Large mammal ecosystems have relatively simple food webs, usually comprising three – and sometimes only two – trophic links. Since many syntopic species from the same trophic level therefore share resources, dietary niche partitioning features prominently within these systems. In African and other subtropical savannas, stable carbon isotopes readily distinguish between herbivore species for which foliage and other parts of dicot plants (13C-depleted C3 vegetation are the primary resource (browsers and those for which grasses (13C-enriched C4 vegetation are staples (grazers. Similarly, carbon isotopes distinguish between carnivore diets that may be richer in either browser, grazer, or intermediate-feeding prey. Here, we investigate levels of carbon and nitrogen isotopic niche variation and niche partitioning within populations (or species of carnivores and herbivores from South African savannas. We emphasize predictable differences in within-population trends across trophic levels: we expect that herbivore populations, which require more foraging effort due to higher intake requirements, are far less likely to display within-population resource partitioning than carnivore populations. Our results reveal generally narrower isotopic niche breadths in herbivore than carnivore populations, but more importantly we find lower levels of isotopic differentiation across individuals within herbivore species. While these results offer some support for our general hypothesis, the current paucity of isotopic data for African carnivores limits our ability to test the complete set of predictions arising from our hypothesis. Nevertheless, given the different ecological and ecophysiological constraints to foraging behaviour within each trophic level, comparisons across carnivores and herbivores, which are possible within such simplified foodwebs, make these systems ideal for developing a process-based understanding of conditions underlying the evolution of

  6. Are Tree Species Diversity and Genotypic Diversity Effects on Insect Herbivores Mediated by Ants?

    Science.gov (United States)

    Campos-Navarrete, María José; Abdala-Roberts, Luis; Munguía-Rosas, Miguel A.; Parra-Tabla, Víctor

    2015-01-01

    Plant diversity can influence predators and omnivores and such effects may in turn influence herbivores and plants. However, evidence for these ecological feedbacks is rare. We evaluated if the effects of tree species (SD) and genotypic diversity (GD) on the abundance of different guilds of insect herbivores associated with big-leaf mahogany (Swietenia macrophylla) were contingent upon the protective effects of ants tending extra-floral nectaries of this species. This study was conducted within a larger experiment consisting of mahogany monocultures and species polycultures of four species and –within each of these two plot types– mahogany was represented by either one or four maternal families. We selected 24 plots spanning these treatment combinations, 10 mahogany plants/plot, and within each plot experimentally reduced ant abundance on half of the selected plants, and surveyed ant and herbivore abundance. There were positive effects of SD on generalist leaf-chewers and sap-feeders, but for the latter group this effect depended on the ant reduction treatment: SD positively influenced sap-feeders under ambient ant abundance but had no effect when ant abundance was reduced; at the same time, ants had negative effects on sap feeders in monoculture but no effect in polyculture. In contrast, SD did not influence specialist stem-borers or leaf-miners and this effect was not contingent upon ant reduction. Finally, GD did not influence any of the herbivore guilds studied, and such effects did not depend on the ant treatment. Overall, we show that tree species diversity influenced interactions between a focal plant species (mahogany) and ants, and that such effects in turn mediated plant diversity effects on some (sap-feeders) but not all the herbivores guilds studied. Our results suggest that the observed patterns are dependent on the combined effects of herbivore identity, diet breadth, and the source of plant diversity. PMID:26241962

  7. Impact of herbivore identity on algal succession and coral growth on a Caribbean reef.

    Directory of Open Access Journals (Sweden)

    Deron E Burkepile

    Full Text Available BACKGROUND: Herbivory is an important top-down force on coral reefs that regulates macroalgal abundance, mediates competitive interactions between macroalgae and corals, and provides resilience following disturbances such as hurricanes and coral bleaching. However, reductions in herbivore diversity and abundance via disease or over-fishing may harm corals directly and may indirectly increase coral susceptibility to other disturbances. METHODOLOGY AND PRINCIPAL FINDINGS: In two experiments over two years, we enclosed equivalent densities and masses of either single-species or mixed-species of herbivorous fishes in replicate, 4 m(2 cages at a depth of 17 m on a reef in the Florida Keys, USA to evaluate the effects of herbivore identity and species richness on colonization and development of macroalgal communities and the cascading effects of algae on coral growth. In Year 1, we used the redband parrotfish (Sparisoma aurofrenatum and the ocean surgeonfish (Acanthurus bahianus; in Year 2, we used the redband parrotfish and the princess parrotfish (Scarus taeniopterus. On new substrates, rapid grazing by ocean surgeonfish and princess parrotfish kept communities in an early successional stage dominated by short, filamentous algae and crustose coralline algae that did not suppress coral growth. In contrast, feeding by redband parrotfish allowed an accumulation of tall filaments and later successional macroalgae that suppressed coral growth. These patterns contrast with patterns from established communities not undergoing primary succession; on established substrates redband parrotfish significantly reduced upright macroalgal cover while ocean surgeonfish and princess parrotfish allowed significant increases in late successional macroalgae. SIGNIFICANCE: This study further highlights the importance of biodiversity in affecting ecosystem function in that different species of herbivorous fishes had very different impacts on reef communities depending on

  8. Interactive effects of fire and large herbivores on web-building spiders.

    Science.gov (United States)

    Foster, C N; Barton, P S; Wood, J T; Lindenmayer, D B

    2015-09-01

    Altered disturbance regimes are a major driver of biodiversity loss worldwide. Maintaining or re-creating natural disturbance regimes is therefore the focus of many conservation programmes. A key challenge, however, is to understand how co-occurring disturbances interact to affect biodiversity. We experimentally tested for the interactive effects of prescribed fire and large macropod herbivores on the web-building spider assemblage of a eucalypt forest understorey and investigated the role of vegetation in mediating these effects using path analysis. Fire had strong negative effects on the density of web-building spiders, which were partly mediated by effects on vegetation structure, while negative effects of large herbivores on web density were not related to changes in vegetation. Fire amplified the effects of large herbivores on spiders, both via vegetation-mediated pathways and by increasing herbivore activity. The importance of vegetation-mediated pathways and fire-herbivore interactions differed for web density and richness and also differed between web types. Our results demonstrate that for some groups of web-building spiders, the effects of co-occurring disturbance drivers may be mostly additive, whereas for other groups, interactions between drivers can amplify disturbance effects. In our study system, the use of prescribed fire in the presence of high densities of herbivores could lead to reduced densities and altered composition of web-building spiders, with potential cascading effects through the arthropod food web. Our study highlights the importance of considering both the independent and interactive effects of disturbances, as well as the mechanisms driving their effects, in the management of disturbance regimes. PMID:25935217

  9. Are Tree Species Diversity and Genotypic Diversity Effects on Insect Herbivores Mediated by Ants?

    Directory of Open Access Journals (Sweden)

    María José Campos-Navarrete

    Full Text Available Plant diversity can influence predators and omnivores and such effects may in turn influence herbivores and plants. However, evidence for these ecological feedbacks is rare. We evaluated if the effects of tree species (SD and genotypic diversity (GD on the abundance of different guilds of insect herbivores associated with big-leaf mahogany (Swietenia macrophylla were contingent upon the protective effects of ants tending extra-floral nectaries of this species. This study was conducted within a larger experiment consisting of mahogany monocultures and species polycultures of four species and -within each of these two plot types- mahogany was represented by either one or four maternal families. We selected 24 plots spanning these treatment combinations, 10 mahogany plants/plot, and within each plot experimentally reduced ant abundance on half of the selected plants, and surveyed ant and herbivore abundance. There were positive effects of SD on generalist leaf-chewers and sap-feeders, but for the latter group this effect depended on the ant reduction treatment: SD positively influenced sap-feeders under ambient ant abundance but had no effect when ant abundance was reduced; at the same time, ants had negative effects on sap feeders in monoculture but no effect in polyculture. In contrast, SD did not influence specialist stem-borers or leaf-miners and this effect was not contingent upon ant reduction. Finally, GD did not influence any of the herbivore guilds studied, and such effects did not depend on the ant treatment. Overall, we show that tree species diversity influenced interactions between a focal plant species (mahogany and ants, and that such effects in turn mediated plant diversity effects on some (sap-feeders but not all the herbivores guilds studied. Our results suggest that the observed patterns are dependent on the combined effects of herbivore identity, diet breadth, and the source of plant diversity.

  10. Are Tree Species Diversity and Genotypic Diversity Effects on Insect Herbivores Mediated by Ants?

    Science.gov (United States)

    Campos-Navarrete, María José; Abdala-Roberts, Luis; Munguía-Rosas, Miguel A; Parra-Tabla, Víctor

    2015-01-01

    Plant diversity can influence predators and omnivores and such effects may in turn influence herbivores and plants. However, evidence for these ecological feedbacks is rare. We evaluated if the effects of tree species (SD) and genotypic diversity (GD) on the abundance of different guilds of insect herbivores associated with big-leaf mahogany (Swietenia macrophylla) were contingent upon the protective effects of ants tending extra-floral nectaries of this species. This study was conducted within a larger experiment consisting of mahogany monocultures and species polycultures of four species and -within each of these two plot types- mahogany was represented by either one or four maternal families. We selected 24 plots spanning these treatment combinations, 10 mahogany plants/plot, and within each plot experimentally reduced ant abundance on half of the selected plants, and surveyed ant and herbivore abundance. There were positive effects of SD on generalist leaf-chewers and sap-feeders, but for the latter group this effect depended on the ant reduction treatment: SD positively influenced sap-feeders under ambient ant abundance but had no effect when ant abundance was reduced; at the same time, ants had negative effects on sap feeders in monoculture but no effect in polyculture. In contrast, SD did not influence specialist stem-borers or leaf-miners and this effect was not contingent upon ant reduction. Finally, GD did not influence any of the herbivore guilds studied, and such effects did not depend on the ant treatment. Overall, we show that tree species diversity influenced interactions between a focal plant species (mahogany) and ants, and that such effects in turn mediated plant diversity effects on some (sap-feeders) but not all the herbivores guilds studied. Our results suggest that the observed patterns are dependent on the combined effects of herbivore identity, diet breadth, and the source of plant diversity. PMID:26241962

  11. Assessing the role of large herbivores in the structuring and functioning of freshwater and marine angiosperm ecosystems

    NARCIS (Netherlands)

    Bakker, Elisabeth S.; Pagès, Jordi F.; Arthur, Rohan; Alcoverro, Teresa

    2016-01-01

    While large herbivores can have strong impacts on terrestrial ecosystems, much less is known of their role in aquatic systems. We reviewed the literature to determine: (1) which large herbivores (>10 kg) have a (semi-)aquatic lifestyle and are important consumers of submerged vascular plants, (2) th

  12. 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.; Boutin, Stan

    2009-01-01

    We tested whether there is a relationship between plant N concentration and herbivore impact on soil N availability (measured with resin bags) with a study of replicate 6-8 year old exclosures (with an unfenced control) of vertebrate herbivores (> 1 kg) established at each of seven grassland sites i

  13. Resource partitioning among African savanna herbivores in North Cameroon: the importance of diet composition, food quality and body mass

    NARCIS (Netherlands)

    Iongh, de H.H.; Jong, de C.B.; Goethem, J.; Klop, E.; Brunsting, A.M.H.; Loth, P.E.; Prins, H.H.T.

    2011-01-01

    The relationship between herbivore diet quality, and diet composition (the range of food plants consumed) and body mass on resource partitioning of herbivores remains the subject of an ongoing scientific debate. In this study we investigated the importance of diet composition and diet quality on res

  14. Herbivore-mediated material fluxes in a northern deciduous forest under elevated carbon dioxide and ozone concentrations.

    Science.gov (United States)

    Meehan, Timothy D; Couture, John J; Bennett, Alison E; Lindroth, Richard L

    2014-10-01

    Anthropogenic changes in atmospheric carbon dioxide (CO2 ) and ozone (O3 ) are known to alter tree physiology and growth, but the cascading effects on herbivore communities and herbivore-mediated nutrient cycling are poorly understood. We sampled herbivore frass, herbivore-mediated greenfall, and leaf-litter deposition in temperate forest stands under elevated CO2 (c. 560 ppm) and O3 (c. 1.5× ambient), analyzed substrate chemical composition, and compared the quality and quantity of fluxes under multiple atmospheric treatments. Leaf-chewing herbivores fluxed 6.2 g m(-2)  yr(-1) of frass and greenfall from the canopy to the forest floor, with a carbon : nitrogen (C : N) ratio 32% lower than that of leaf litter. Herbivore fluxes of dry matter, C, condensed tannins, and N increased under elevated CO2 (35, 32, 63 and 39%, respectively), while fluxes of N decreased (18%) under elevated O3 . Herbivore-mediated dry matter inputs scaled across atmospheric treatments as a constant proportion of leaf-litter inputs. Increased fluxes under elevated CO2 were consistent with increased herbivore consumption and abundance, and with increased plant growth and soil respiration, previously reported for this experimental site. Results suggest that insect herbivory will reinforce other factors, such as photosynthetic rate and fine-root production, impacting C sequestration by forests in future environments. PMID:25078062

  15. Defense suppression benefits herbivores that have a monopoly on their feeding site but can backfire within natural communities.

    NARCIS (Netherlands)

    J.J. Glas; J.M. Alba; S. Simoni; C.A. Villarroel; M. Stoops; B. Schimmel; R.C. Schuurink; M.W. Sabelis; M.R. Kant

    2014-01-01

    Background: Plants have inducible defenses to combat attacking organisms. Hence, some herbivores have adapted to suppress these defenses. Suppression of plant defenses has been shown to benefit herbivores by boosting their growth and reproductive performance. Results: We observed in field-grown toma

  16. Assessing the consequences of global change for forest disturbance from herbivores and pathogens

    Energy Technology Data Exchange (ETDEWEB)

    Ayres, M.P.; Lombardero, M.J. [Department of Biological Sciences, Dartmouth College, NH 03755-3576 Hanover (United States)

    2000-11-15

    Herbivores and pathogens impact the species composition, ecosystem function, and socioeconomic value of forests. Herbivores and pathogens are an integral part of forests, but sometimes produce undesirable effects and a degradation of forest resources. In the United States, a few species of forest pests routinely have significant impacts on up to 20 million ha of forest with economic costs that probably exceed $1 billion/year. Climatic change could alter patterns of disturbance from herbivores and pathogens through: (1) direct effects on the development and survival of herbivores and pathogens; (2) physiological changes in tree defenses; and (3) indirect effects from changes in the abundance of natural enemies (e.g. parasitoids of insect herbivores), mutualists (e.g. insect vectors of tree pathogens), and competitors. Because of their short life cycles, mobility, reproductive potential, and physiological sensitivity to temperature, even modest climate change will have rapid impacts on the distribution and abundance of many forest insects and pathogens. We identify 32 syndromes of biotic disturbance in North American forests that should be carefully evaluated for their responses to climate change: 15 insect herbivores, browsing mammals; 12 pathogens; 1 plant parasite; and 3 undiagnosed patterns of forest decline. It is probable that climatic effects on some herbivores and pathogens will impact on biodiversity, recreation, property value, forest industry, and even water quality. Some scenarios are beneficial (e.g. decreased snow cover may increase winter mortality of some insect pests), but many are detrimental (e.g. warming tends to accelerate insect development rate and facilitate range expansions of pests and climate change tends to produce a mismatch between mature trees and their environment, which can increase vulnerability to herbivores and pathogens). Changes in forest disturbance can produce feedback to climate through affects on water and carbon flux in

  17. Toxicity of a furanocoumarin to armyworms: a case of biosynthetic escape from insect herbivores.

    Science.gov (United States)

    Berenbaum, M

    1978-08-11

    When the linear furanocoumarin xanthotoxin, found in many plants of the families Rutaceae and Umbelliferae, was administered to larvae of Spodoptera eridania, a generalist insect herbivore, it displayed toxic properties lacking in its biosynthetic precursor umbelliferone. Reduced toxicity observed in the absence of ultraviolet light is consistent with the known mechanism of photoinactivation of DNA by furanocoumarins through ultraviolet-catalyzed cross-linkage of strands. Thus, the ability of a plant to convert umbelliferone to linear furanocoumarins appears to confer broader protection against insect herbivores. PMID:17790440

  18. Tracing hidden herbivores: Time-resolved non-invasive analysis of belowground volatiles by proton-transfer-reaction mass spectrometry (PTR-MS)

    OpenAIRE

    Danner, H.; Samudrala, D.; Cristescu, S M; Van Dam, N.M.

    2012-01-01

    Root herbivores are notoriously difficult to study, as they feed hidden in the soil. However, root herbivores may be traced by analyzing specific volatile organic compounds (VOCs) that are produced by damaged roots. These VOCs not only support parasitoids in the localization of their host, but also may help scientists study belowground plant-herbivore interactions. Herbivore-induced VOCs are usually analyzed by gas-chromatography mass spectrometry (GC-MS), but with this off-line method, the g...

  19. Assessing the short-term impact of an insecticide (Deltamethrin) on predator and herbivore abundance in soybean Glycine max using a replicated small-plot field experiment

    Institute of Scientific and Technical Information of China (English)

    Sarina Macfadyen; Myron P. Zalucki

    2012-01-01

    A greater understanding of the relative impact of insecticide use on non-target species is critical for the incorporation of natural enemies into integrated pest management strategies.Here we use a small-plot field trial to examine the relative impact of an insecticide on herbivores and predators found in soybean (Glycine max L.),and to highlight the issues associated with calculating impact factors from these studies.The pyrethroid insecticide (Deltamethrin) caused a significant reduction in invertebrate abundance in the treated plots,and populations did not recover to pre-treatment levels even 20 days after spraying.To assess the relative impact of the spray on arthropods we first examined the mean difference in abundance in each plot before and after spraying.All herbivores decreased in abundance in the sprayed plots but increased in the control plots after spraying.Most predators (excluding hemipterans) showed a decrease in the control plots but a proportionally greater decrease in the sprayed plots.Next we examined the corrected percentage population reduction calculated using Abbott's formula.All predators (including Araneae) experienced a greater reduction (mean 87% ± 3.54 SE) than herbivores (mean 56% ± 4.37 SE) and Araneae alone (mean 71% ± 8.12 SE).The range in values across the plots varied and made categorising overall impact subjective for some taxa.Despite the constraints associated with small-plot trials,by using a combination of impact factors and examining community-level response across time,we did get some indication of the likely impact of this insecticide if used in a commercial situation.

  20. Qualitative and event-specific real-time PCR detection methods for Bt brinjal event EE-1.

    Science.gov (United States)

    Randhawa, Gurinder Jit; Sharma, Ruchi; Singh, Monika

    2012-01-01

    Bt brinjal event EE-1 with cry1Ac gene, expressing insecticidal protein against fruit and shoot borer, is the first genetically modified food crop in the pipeline for commercialization in India. Qualitative polymerase chain reaction (PCR) along with event-specific conventional as well as real-time PCR methods to characterize the event EE-1 is reported. A multiplex (pentaplex) PCR system simultaneously amplifying cry1Ac transgene, Cauliflower Mosaic Virus (CaMV) 35S promoter, nopaline synthase (nos) terminator, aminoglycoside adenyltransferase (aadA) marker gene, and a taxon-specific beta-fructosidase gene in event EE-1 has been developed. Furthermore, construct-specific PCR, targeting the approximate 1.8 kb region of inserted gene construct comprising the region of CaMV 35S promoter and cry1Ac gene has also been developed. The LOD of developed EE-1 specific conventional PCR assay is 0.01%. The method performance of the reported real-time PCR assay was consistent with the acceptance criteria of Codex Alimentarius Commission ALINORM 10/33/23, with the LOD and LOQ values of 0.05%. The developed detection methods would not only facilitate effective regulatory compliance for identification of genetic traits, risk assessment, management, and postrelease monitoring, but also address consumer concerns and resolution of legal disputes. PMID:23451391

  1. Bt proteins Cry1Ah and Cry2Ab do not affect cotton aphid Aphis gossypii and ladybeetle Propylea japonica.

    Science.gov (United States)

    Zhao, Yao; Zhang, Shuai; Luo, Jun-Yu; Wang, Chun-Yi; Lv, Li-Min; Wang, Xiao-Ping; Cui, Jin-Jie; Lei, Chao-Liang

    2016-01-01

    Plant varieties expressing the Bt (Bacillus thuringiensis) insecticidal proteins Cry1Ah and Cry2Ab have potential commercialization prospects in China. However, their potential effects on non-target arthropods (NTAs) remain uncharacterized. The cotton aphid Aphis gossypii is a worldwide pest that damages various important crops. The ladybeetle Propylea japonica is a common and abundant natural enemy in many cropping systems in East Asia. In the present study, the effects of Cry1Ah and Cry2Ab proteins on A. gossypii and P. japonica were assessed from three aspects. First, neither of the Cry proteins affected the growth or developmental characteristics of the two test insects. Second, the expression levels of the detoxification-related genes of the two test insects did not change significantly in either Cry protein treatment. Third, neither of the Cry proteins had a favourable effect on the expression of genes associated with the amino acid metabolism of A. gossypii and the nutrition utilization of P. japonica. In conclusion, the Cry1Ah and Cry2Ab proteins do not appear to affect the cotton aphid A. gossypii or the ladybeetle P. japonica. PMID:26829252

  2. Assessment of the Philips BT-S4 Bucky tomography system

    International Nuclear Information System (INIS)

    The BT-S4 system is a microprocessor controlled tomographic unit with a wide range of other radiographic applications. It was assessed with a Philips TM 100 generator which has the capability of controlling X-ray tube voltage and current during the exposure. The results from the BT-S4 system were, in general, good and up to the standard of those from other systems, though one assessor thought the images to be less sharp. For linear tomography, an extra angle to get a thickness of cut between the extremes available was thought desirable. The assessment report recommends a number of design improvements for which the need became apparent during use of the equipment in KCARE, King's College Hospital. (author)

  3. 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.

  4. Effekte des Anbaus von Bt-Mais auf Nichtzielarthropoden der Krautschichtfauna : Monitoringorganismen und praktikable Erfassungsmethoden

    OpenAIRE

    Eckert, Jörg

    2006-01-01

    A 3-year study (2001-2003) was conducted to determine possible unintended effects of Bt-maize (Mon810, cultivar Novelis) cultivation on nontarget organisms of the arthropod community compared with an isogenic maize line (cultivar Nobilis) with and without an insecticide treatment. Furthermore, suitable monitoring organisms and appropriate methods are recommended for Post Market Environmental Monitoring. The experimental site was situated near Bonn (Germany) and consisted of two maize fields d...

  5. Bt Brinjal: Introducing Genetically Modified Brinjal (Eggplant/Aubergine) in Bangladesh

    OpenAIRE

    Mst. Meherunnahar; D. N. R. Paul

    2009-01-01

    Brinjal, also known as eggplant and aubergine, is Bangladesh’s third most important vegetable in terms of both yield and area cultivated. It is only surpassed by potatoes and onions. However, the yield of brinjal could be much higher would it not be decimated by the brinjal shoot and fruit borer, which is the most destructive insect pest in South and South East Asia. Genetically modified brinjal (Bt brinjal) has the potential to bump up agricultural productivity in Bangladesh and other countr...

  6. Pengaruh Kualitas Pelayanan Terhadap Loyalitas Pelanggan Melalui Kepuasan Pelanggan Pada BT/BS BIMA Medan

    OpenAIRE

    Tanjung, Hilman

    2015-01-01

    The purposes of this research are to analyize the impact of services quality on customers loyality, the impact of services quality on customers satisfaction, the impact of customers loyality on customers satisfaction, and the impact of services quality on customers loyality through customers satisfaction. This is an asosiative research. The methods of collecting data were based on primary data using questionnaires where the location of this research take place on BT/BS Bima that the account o...

  7. A Meta-Analysis of Effects of Bt Crops on Honey Bees (Hymenoptera: Apidae)

    OpenAIRE

    Jian J Duan; Michelle Marvier; Joseph Huesing; Galen Dively; Zachary Y Huang

    2008-01-01

    BACKGROUND: Honey bees (Apis mellifera L.) are the most important pollinators of many agricultural crops worldwide and are a key test species used in the tiered safety assessment of genetically engineered insect-resistant crops. There is concern that widespread planting of these transgenic crops could harm honey bee populations. METHODOLOGY/PRINCIPAL FINDINGS: We conducted a meta-analysis of 25 studies that independently assessed potential effects of Bt Cry proteins on honey bee survival (or ...

  8. Brain pharmacokinetics of ganciclovir in rats with orthotopic BT4C glioma.

    Science.gov (United States)

    Gynther, Mikko; Kääriäinen, Tiina M; Hakkarainen, Jenni J; Jalkanen, Aaro J; Petsalo, Aleksanteri; Lehtonen, Marko; Peura, Lauri; Kurkipuro, Jere; Samaranayake, Haritha; Ylä-Herttuala, Seppo; Rautio, Jarkko; Forsberg, Markus M

    2015-01-01

    Ganciclovir (GCV) is an essential part of the Herpes simplex virus thymidine kinase (HSV-tk) gene therapy of malignant gliomas. The purpose of this study was to investigate the brain pharmacokinetics and tumor uptake of GCV in the BT4C rat glioma model. GCV's brain and tumor uptakes were investigated by in vivo microdialysis in rats with orthotopic BT4C glioma. In addition, the ability of GCV to cross the blood-brain barrier and tumor vasculature was assessed with in situ rat brain perfusion. Finally, the extent to which GCV could permeate across the BT4C glioma cell membrane was assessed in vitro. The areas under the concentration curve of unbound GCV in blood, brain extracellular fluid (ECF), and tumor ECF were 6157, 1658, and 4834 μM⋅min, respectively. The apparent maximum unbound concentrations achieved within 60 minutes were 46.9, 11.8, and 25.8 μM in blood, brain, and tumor, respectively. The unbound GCV concentrations in brain and tumor after in situ rat brain perfusion were 0.41 and 1.39 nmol/g, respectively. The highly polar GCV likely crosses the fenestrated tumor vasculature by paracellular diffusion. Thus, GCV is able to reach the extracellular space around the tumor at higher concentrations than that in healthy brain. However, GCV uptake into BT4C cells at 100 μM was only 2.1 pmol/mg of protein, and no active transporter-mediated disposition of GCV could be detected in vitro. In conclusion, the limited efficacy of HSV-tk/GCV gene therapy may be due to the poor cellular uptake and rapid elimination of GCV. PMID:25349125

  9. Binding and Oligomerization of Modified and Native Bt Toxins in Resistant and Susceptible Pink Bollworm.

    Directory of Open Access Journals (Sweden)

    Josue Ocelotl

    Full Text Available Insecticidal proteins from Bacillus thuringiensis (Bt are used extensively in sprays and transgenic crops for pest control, but their efficacy is reduced when pests evolve resistance. Better understanding of the mode of action of Bt toxins and the mechanisms of insect resistance is needed to enhance the durability of these important alternatives to conventional insecticides. Mode of action models agree that binding of Bt toxins to midgut proteins such as cadherin is essential for toxicity, but some details remain unresolved, such as the role of toxin oligomers. In this study, we evaluated how Bt toxin Cry1Ac and its genetically engineered counterpart Cry1AcMod interact with brush border membrane vesicles (BBMV from resistant and susceptible larvae of Pectinophora gossypiella (pink bollworm, a global pest of cotton. Compared with Cry1Ac, Cry1AcMod lacks 56 amino acids at the amino-terminus including helix α-1; previous work showed that Cry1AcMod formed oligomers in vitro without cadherin and killed P. gossypiella larvae harboring cadherin mutations linked with >1000-fold resistance to Cry1Ac. Here we found that resistance to Cry1Ac was associated with reduced oligomer formation and insertion. In contrast, Cry1AcMod formed oligomers in BBMV from resistant larvae. These results confirm the role of cadherin in oligomerization of Cry1Ac in susceptible larvae and imply that forming oligomers without cadherin promotes toxicity of Cry1AcMod against resistant P. gossypiella larvae that have cadherin mutations.

  10. Flexible Working in BT: An investigation into Motivation, Productivity and Job Satisfaction

    OpenAIRE

    Harford, Anthony David

    2006-01-01

    British Telecommunications plc (BT) began introducing flexible working initiatives in the early 1990s. The uptake across the company has been varied as many individual and contextual factors have influenced the employee when deciding upon how and where to work. Much of the research on the matter appears to only assess impact and analysis up to 2002, and although internal surveys ( CARE ) have included question sets on flexible working little or no primary research has been undertaken specific...

  11. Factors related to recurrence of bladder transitional cell carcinoma after transurethral resection of bladder tumor (TUR-BT)

    International Nuclear Information System (INIS)

    The purpose of this study is to evaluate factors related to the recurrence of TCC (transitional cell carcinoma) in the urinary bladder after transurethal resection of bladder tumor (TUR-BT). We retrospectively reviewed 54 patients in whom TCC (transitional cell carcinoma) after TUR-BT had been confirmed. Recurrence was evaluated by US, CT, cystoscopy and urine smear during the follow-up period of 6 months. The multiplicity, shape, size, and calcification of TCC, as revealed by radiologic studies, were evaluated retrospectively before TUR-BT. After TUR-BT, the histologic grade and pathologic stage of TCC were evaluated. Radiologically, multiple and/or sessile type TCC had a higher recurrence rate than the single and/or pedunculated type. Pathologically, when the grade and stage of bladder tumor were higher, recurrent rates were higher. (author). 17 refs., 3 tabs., 3 figs

  12. Structure of BT-3984, a member of the SusD/RagB family of nutrient-binding molecules

    International Nuclear Information System (INIS)

    The crystal structure of BT-3984, a SusD-family protein, reveals a TPR N-terminal region providing support for a loop-rich C-terminal subdomain and suggests possible interfaces involved in sus complex formation. The crystal structure of the Bacteroides thetaiotaomicron protein BT-3984 was determined to a resolution of 1.7 Å and was the first structure to be determined from the extensive SusD family of polysaccharide-binding proteins. SusD is an essential component of the sus operon that defines the paradigm for glycan utilization in dominant members of the human gut microbiota. Structural analysis of BT-3984 revealed an N-terminal region containing several tetratricopeptide repeats (TPRs), while the signature C-terminal region is less structured and contains extensive loop regions. Sequence and structure analysis of BT-3984 suggests the presence of binding interfaces for other proteins from the polysaccharide-utilization complex

  13. Pure and Nd added NBT-BT single crystals - Growth and their characterization

    Science.gov (United States)

    Sundari, S. Shanmuga; Baskar, K.; Dhanasekaran, R.

    2014-04-01

    The lead free piezoelectric materials are secured an important place in the field of material science and engineering. In the present work single crystals of sodium bismuth titanate- barium titanate (0.94NBT-0.06BT) and 0.6 wt % of Nd added NBT-BT has been grown by flux method. The addition of 0.6 wt% of Nd shows the inhomogeneity in melt and the crystals collected from the top, middle and bottom portions of the crucible have been characterized for their structural and dielectric properties. The Nd concentration is found to be more in the crystals grown from the bottom portion of crucible and it was confirmed by optical and structural analysis. After the addition of Nd the color of the crystal changes form pale yellow to muddy green. The depolarization temperature (Td) and the temperature where the dielectric constant reaches its maximum (Tm) are increased from 442 K to 475 K and 595 K and 628 K respectively after the addition the of Nd in NBT-BT.

  14. Studies on Rapid Quantitative Analysis of Bt Toxin by Using Envirologix Kits in Transgenic Rice

    Institute of Scientific and Technical Information of China (English)

    XIE Xiao-bo; SHU Qing-yao

    2002-01-01

    Investigations were done on the usefulness of Envirologix Cry1Ab/Cry1Ac Plate kits for quantitative analysis of Bt toxin content in transgenic rice grains. Two transgenic rice lines: Kemingdao 1 (KMD1) and Kemingdao 2 (KMD2), transformed with a cry1Ab gene, and their parental variety, cv.Xiushui 11, were used as positive and negative samples. Results showed that the correlation coefficients as high as 0. 985 - 0. 998, significant at probability level of 0.05 or 0.01, were obtained for linear regression equations by using the appended calibrators of the kits. No significant differences were detected for values of same rice sample obtained from different trials or by using different lots of the product (kit). The detectable Bt toxin content by this method could be as low as 0.5 ng/g. The Envirologix Kit could be useful for rapid quantitative detection of Bt toxin in rice grains because of its preciseness, simplicity and time saving.

  15. Variation induced by DNA rearrangement in a transgenic Bt+CpTI cotton strain

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In the development of transgenic Bt + CpTI cotton cultivars, one male and female sterile mutant has been found in a homozygous T4 strain in our laboratory. The mutant plant, as well as its leaves, buds and flowers, is only 1/2-1/3 as large as that of the wild transgenic Bt + CpTI bivalant cotton plants. Cytological observation found that the chromosome number of the mutant is 2n = 52; however, there are 4 - 8 univalents observed in meiosis Ⅰ of pollen mother cells. Laboratory bioassay indicated that the mutant was highly resistant to bollworm as the wild plants. PCR amplification revealed that Bt and CpTI genes in the mutant were still intactly inserted. However, small deletion of flanked area had been observed in the mutant by Southern blotting analysis. So it is proposed that the mutant phenotype might result from either the DNA deletion or T-DNA trans-ferring in plant genome. No such report has been presented that the rearrangement of chromosome structure in a homo-zygous transgenic line occurred. Further analysis is ongoing.

  16. Characterization of neutral lipase BT-1 isolated from the labial gland of Bombus terrestris males.

    Directory of Open Access Journals (Sweden)

    Jana Brabcová

    Full Text Available BACKGROUND: In addition to their general role in the hydrolysis of storage lipids, bumblebee lipases can participate in the biosynthesis of fatty acids that serve as precursors of pheromones used for sexual communication. RESULTS: We studied the temporal dynamics of lipolytic activity in crude extracts from the cephalic part of Bombus terrestris labial glands. Extracts from 3-day-old males displayed the highest lipolytic activity. The highest lipase gene expression level was observed in freshly emerged bumblebees, and both gene expression and lipase activity were lower in bumblebees older than 3 days. Lipase was purified from labial glands, further characterized and named as BT-1. The B. terrestris orthologue shares 88% sequence identity with B. impatiens lipase HA. The molecular weight of B. terrestris lipase BT-1 was approximately 30 kDa, the pH optimum was 8.3, and the temperature optimum was 50°C. Lipase BT-1 showed a notable preference for C8-C10 p-nitrophenyl esters, with the highest activity toward p-nitrophenyl caprylate (C8. The Michaelis constant (Km and maximum reaction rate (Vmax for p-nitrophenyl laurate hydrolysis were Km = 0.0011 mM and Vmax = 0.15 U/mg. CONCLUSION: This is the first report describing neutral lipase from the labial gland of B. terrestris. Our findings help increase understanding of its possible function in the labial gland.

  17. Pyramids of QTLs enhance host–plant resistance and Bt-mediated resistance to leaf-chewing insects in soybean

    OpenAIRE

    Ortega, María A.; All, John N.; Boerma, H. Roger; Parrott, Wayne A.

    2016-01-01

    Key message QTL-M and QTL-E enhance soybean resistance to insects. Pyramiding these QTLs with cry1Ac increases protection against Bt-tolerant pests, presenting an opportunity to effectively deploy Bt with host–plant resistance genes. Abstract Plant resistance to leaf-chewing insects minimizes the need for insecticide applications, reducing crop production costs and pesticide concerns. In soybean [Glycine max (L.) Merr.], resistance to a broad range of leaf-chewing insects is found in PI 22935...

  18. Delta's Key to the Next Generation TOEFL[R] Test: Six Practice Tests for the iBT

    Science.gov (United States)

    Gallagher, Nancy

    2012-01-01

    Six Practice Tests for the iBT gives students plenty of practice as they prepare for the Internet-based TOEFL (iBT) or the new form of the institutional TOEFL (ITP). This new book/audio set contains a concise description of the TOEFL and the types of questions in each section, as well as six full-length tests that have not been published before.…

  19. Commercial production of transgenic Bt insect-resistant cotton varieties and the resistance management for bollworm (Helicoverpa armigera Hubner)

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    There are currently three kinds of transgenic Bt insect-resistant cotton germplasm lines, Shanxi 94-24, Zhongxin 94 and R19, in China. They showed high resistance to the neonate larvae of bollworm (Helicoverpa armigera). Transgenic Bt insect-resistant cotton varieties or hybrids have been bred using the three kinds of germplasm lines as parents. Our researches reveal that there exist different expressions in resistant level at different developmental stages in the three categories of germplasm lines. When neonate larvae are fed with leaves of cotton plant at the seeding stage with less than 10 leaves on the main stem, the mortality of the neonate larvae is 100%, but the resistance level will decline at later season. When Bt gene has been transferred to the cotton genome, it can be steadily transferred to the progeny, the level of resistance to bollworm keeps fundamentally uniform. Such insects as tobacco budworm (Heliothis virencens) in laboratory directive selection are very apt to produce resistance to the Bt insecticidal crystal protein. From the present crop system of cotton region in the Yangtze and Yellow River Valleys, and the expression characteristic of transgenic Bt resistant cotton, we suggest that the resistance to toxin protein in bollworm is not apt to be produced if the transgenic Bt insect-resistant cotton varieties are released and grown in the regions except in the Xinjiang cotton region. The managing strategies to delay or retard the resistance are discussed.

  20. Change in behavioral response to herbivore-induced plant volatiles in a predatory mite population

    NARCIS (Netherlands)

    Dicke, M.; Schuette, C.; Dijkman, H.

    2000-01-01

    Damage by herbivorous spider mites induces plants to produce volatiles that attract predatory mites that consume the spider mites. A clear attraction to volatiles from Lima bean plants infested with the spider mite Tetranychus urticae has been consistently reported during more than 15 years for the

  1. 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...

  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. Innate responses of the predatory mite Phytoseiulus persimilis to a herbivore-induced plant volatile

    NARCIS (Netherlands)

    B. Sznajder; M.W. Sabelis; M. Egas

    2011-01-01

    The responses of the predatory mite P. persimilis to herbivore-induced plant volatiles are at least partly genetically determined. Thus, there is potential for the evolution of this behaviour by natural selection. We tested whether distinct predator genotypes with contrasting responses to a specific

  4. Complex odour from plants under attack: herbivore's enemies react to the whole, not its parts.

    NARCIS (Netherlands)

    M. van Wijk; P.J.A. de Bruijn; M.W. Sabelis

    2011-01-01

    Background Insect herbivory induces plant odors that attract herbivores' natural enemies. Assuming this attraction emerges from individual compounds, genetic control over odor emission of crops may provide a rationale for manipulating the distribution of predators used for pest control. However, stu

  5. OsWRKY53, a versatile switch in regulating herbivore-induced defense responses in rice.

    Science.gov (United States)

    Hu, Lingfei; Ye, Meng; Li, Ran; Lou, Yonggen

    2016-04-01

    WRKY proteins, which belong to a large family of plant-specific transcription factors, play important roles in plant defenses against pathogens and herbivores by regulating defense-related signaling pathways. Recently, a rice WRKY transcription factor OsWRKY53 has been reported to function as a negative feedback modulator of OsMPK3/OsMPK6 and thereby to control the size of the investment a rice plant makes to defend against a chewing herbivore, the striped stem borer Chilo suppressalis. We investigated the performance of a piecing-sucking herbivore, the brown planthopper (BPH) Nilaparvata lugens, on transgenic plants that silence or overexpress OsWRKY53, and found that OsWRKY53 activates rice defenses against BPH by activating an H2O2 burst and suppressing ethylene biosynthesis. These findings suggest that OsWRKY53 functions not only as a regulator of plants' investment in specific defenses, but also as a switch to initiate new defenses against other stresses, highlighting the versatility and importance of OsWRKY53 in herbivore-induced plant defenses. PMID:27031005

  6. Crop domestication relaxes both top-down and bottom-up effects on a specialist herbivore

    Science.gov (United States)

    Crop domestication can lead to a wide array of differences in plant traits when compared with those of wild progenitors. These modifications often increase the susceptibility of domestic plants to herbivores and at the same time reduce the efficiency of natural enemies, thereby relaxing both bottom-...

  7. The Multiple Strategies of an Insect Herbivore to Overcome Plant Cyanogenic Glucoside Defence

    OpenAIRE

    Stefan Pentzold; Mika Zagrobelny; Pernille Sølvhøj Roelsgaard; Birger Lindberg Møller; Søren Bak

    2014-01-01

    Cyanogenic glucosides (CNglcs) are widespread plant defence compounds that release toxic hydrogen cyanide by plant bglucosidaseactivity after tissue damage. Specialised insect herbivores have evolved counter strategies and some sequesterCNglcs, but the underlying mechanisms to keep CNglcs intact during feeding and digestion are unknown. We show thatCNglc-sequestering Zygaena filipendulae larvae combine behavioural, morphological, physiological and biochemicalstrategies at different time point...

  8. Are cattle surrogate wildlife? Savanna plant community composition explained by total herbivory, not herbivore identity

    Science.gov (United States)

    The replacement of wild ungulate herbivores by domestic livestock in African savannas is composed of two interrelated phenomena: 1) loss or reduction in numbers of individual wildlife species or guilds, and 2) addition of livestock to the system. Yet very few studies have addressed the individual, c...

  9. Are cattle surrogate wildlife? Savannah plant community composition explained by total herbivory, not herbivore identity

    Science.gov (United States)

    The replacement of wild ungulate herbivores by domestic livestock in African savannas is composed of two interrelated phenomena: 1) loss or reduction in numbers of individual wildlife species or guilds, and 2) addition of livestock to the system. Each has important implications for plant community d...

  10. Herbivores, resources and risks : alternating regulation along primary environmental gradients in savannas

    NARCIS (Netherlands)

    Hopcraft, J. Grant C.; Olff, Han; Sinclair, A. R. E.

    2010-01-01

    Herbivores are regulated by predation under certain environmental conditions, whereas under others they are limited by forage abundance and nutritional quality. Whether top-down or bottom-up regulation prevails depends both on abiotic constraints on forage availability and body size, because size si

  11. Hemolymph Defense against an Invasive Herbivore: Its Breadth of Effectiveness Against Predators

    Science.gov (United States)

    Defensive characteristics of organisms shape the trophic linkages within food webs and influence the ability of invasive organisms to expand their range. Diabrotica virgifera virgifera is an invasive herbivore in European maize, and its subterranean larval feeding affects the entire maize ecosystem....

  12. The importance of termites (Isoptera) for the recycling of herbivore dung in tropical ecosystems : a review

    NARCIS (Netherlands)

    Freymann, Bernd P.; Buitenwerf, Robert; Desouza, Og; Olff, Han

    2008-01-01

    While the key role of termites in the decomposition of litter in the tropics has been acknowledged for a long time, much less information exists on their importance in the recycling of dung of primary consumers, especially herbivores. A review of published studies shows that a diverse group of termi

  13. The importance of termites (Isoptera) for the recycling of herbivore dung in tropical ecosystems: a review

    NARCIS (Netherlands)

    Freymann, B.P.; Buitenwerf, R.; Desouza, O.; Olff, H.

    2008-01-01

    While the key role of termites in the decomposition of litter in the tropics has been acknowledged for a long time, much less information exists on their importance in the recycling of dung of primary consumers, especially herbivores. A review of published studies shows that a diverse group of termi

  14. Responses of herbivorous rodents to habitat disturbance on the North Slope of Alaska. Progress report

    Energy Technology Data Exchange (ETDEWEB)

    Batzli, G.O.

    1985-09-27

    The objectives were: (1) to determine the patterns of distribution and density of rodents along drainage systems, (2) to relate those patterns to changes in vegetation associated with disturbance, (3) to examine the mechanisms that account for observed patterns, (4) to assess changes in nutritional quality of plants after habitat disturbance, and (5) to document movement of nutrients between habitats by herbivores.

  15. Cytokinin levels and signaling respond to wounding and the perception of herbivore elicitors in Nicotiana attenuata

    Czech Academy of Sciences Publication Activity Database

    Schäfer, M.; Meza-Canales, I.D.; Navarro-Quezada, A.; Brütting, C.; Vaňková, Radomíra; Baldwin, I.T.; Meldau, S.

    2015-01-01

    Roč. 57, č. 2 (2015), s. 198-212. ISSN 1672-9072 R&D Projects: GA ČR GA206/09/2062 Institutional support: RVO:61389030 Keywords : Arabidopsis thaliana * cytokinin * herbivore-associated molecular patterns Subject RIV: ED - Physiology Impact factor: 3.335, year: 2014

  16. Effects of herbivores, nutrient enrichment, and their interactions on macroalgal proliferation and coral growth

    Science.gov (United States)

    Sotka, E. E.; Hay, M. E.

    2009-09-01

    We conducted a 20-week manipulative field experiment on shallow forereefs of the Florida Keys to assess the separate and interactive effects of herbivory and nutrient enrichment on the development of macroalgal communities and the fitness of the corals Porites porites and Siderastrea siderea. Excluding large herbivorous fishes produced macrophyte blooms both with and without nutrient enrichment. In contrast, there were no direct effects of nutrient enrichment. There were, however, small, but significant, interactive effects of herbivory and enrichment on macroalgal cover. Following nutrient enrichment, total macroalgae and the common seaweeds Dictyota spp. were suppressed in the presence, but not in the absence, of large herbivorous fishes—suggesting that fishes were selectively feeding on nutrient-enriched macrophytes. Access by large herbivores prevented algal overgrowth of corals, but these large fishes also directly grazed both corals. Excluding fishes did not alter survivorship of either coral species, but did decrease parrotfish grazing scars on both corals and increased the net growth of P. porites. Nutrient additions had no direct effects on the survivorship of corals, but there was a trend ( P = 0.097) for nutrients to stimulate the growth of P. porites. The preponderance of experiments available to date indicates that loss of key herbivores is a major factor driving macroalgal blooms on coral reefs; anthropogenic nutrient pollution generally plays a more minor role.

  17. Genetic and environmental determinants of insect herbivore community structure in a Betula pendula population.

    Science.gov (United States)

    Silfver, Tarja; Rousi, Matti; Oksanen, Elina; Roininen, Heikki

    2014-01-01

    A number of recent studies have shown that intraspecific genetic variation of plants may have a profound effect on the herbivorous communities which depend on them. However less is known about the relative importance of intraspecific variation compared to other ecological factors, for example environmental variation or the effects of herbivore damage. We randomly selected 22 Betula pendula genotypes from a local population (block) variation on a local scale, while on a regional scale, genotypic and environmental (site) variation accounted for 4-14% of the arthropod community structure. The genetic effects were modified by environmental variation on both a local and regional scale over one study year, and locally, the largest part of the variation (38%) could be explained by the genotype × environment (block) interactions. Suppression of insect herbivores during one growing season led to changed arthropod community structure in the following growing season, but this effect was minimal and could explain only 4% of the total variation in insect community structure. Our results suggest that both genetic and environmental factors are important determinants of the community structure of herbivorous insects. Together these mechanisms appear to maintain the high diversity of insects in B. pendula forest ecosystems. PMID:24715977

  18. Behavioral Ecology of Oviposition-Site Selection in Herbivorous True Bugs

    NARCIS (Netherlands)

    Martínez, G.; Soler, R.; Dicke, M.

    2013-01-01

    Optimal oviposition theory predicts that female herbivores will prefer to oviposit on those plants that maximize offspring performance, also known as the “mother knows best” paradigm. This is the general pattern within the insect order Lepidoptera with specialist diets and reduced larval mobility. I

  19. Behavioral Ecology of Oviposition-Site Selection in Herbivorous True Bugs

    NARCIS (Netherlands)

    Martinez, G.; Soler, R.; Dicke, M.; Brockmann, H.J.; Roper, T.J.; Naguib, M.; Mitani, J.C.; Simmons, L.W.; Barrett, L.

    2013-01-01

    Optimal oviposition theory predicts that female herbivores prefer to oviposit on those plants that maximize offspring performance, also known as the “mother knows best” paradigm. This is the general pattern within the insect order Lepidoptera with specialist diets and reduced larval mobility. In tha

  20. Aboveground vertebrate and invertebrate herbivore impact on net N mineralization in subalpine grasslands.

    Science.gov (United States)

    Risch, Anita C; Schotz, Martin; Vandegehuchte, Martijn L; Van Der Putten, Wim H; Duyts, Henk; Raschein, Ursina; Gwiazdowicz, Dariusz J; Busse, Matt D; Page-dumroese, Deborah S; Zimmermann, Stephan

    2015-12-01

    Aboveground herbivores have strong effects on grassland nitrogen (N) cycling. They can accelerate or slow down soil net N mineralization depending on ecosystem productivity and grazing intensity. Yet, most studies only consider either ungulates or invertebrate herbivores, but not the combined effect of several functionally different vertebrate and invertebrate herbivore species or guilds. We assessed how a diverse herbivore community affects net N mineralization in subalpine grasslands. By using size-selective fences, we progressively excluded large, medium, and small mammals, as well as invertebrates from two vegetation types, and assessed how the exclosure types (ET) affected net N mineralization. The two vegetation types differed in long-term management (centuries), forage quality, and grazing history and intensity. To gain a more mechanistic understanding of how herbivores affect net N mineralization, we linked mineralization to soil abiotic (temperature; moisture; NO3-, NH4+, and total inorganic N concentrations/pools; C, N, P concentrations; pH; bulk density), soil biotic (microbial biomass; abundance of collembolans, mites, and nematodes) and plant (shoot and root biomass; consumption; plant C, N, and fiber content; plant N pool) properties. Net N mineralization differed between ET, but not between vegetation types. Thus, short-term changes in herbivore community composition and, therefore, in grazing intensity had a stronger effect on net N mineralization than long-term management and grazing history. We found highest N mineralization values when only invertebrates were present, suggesting that mammals had a negative effect on net N mineralization. Of the variables included in our analyses, only mite abundance and aboveground plant biomass explained variation in net N mineralization among ET. Abundances of both mites and leaf-sucking invertebrates were positively correlated with aboveground plant biomass, and biomass increased with progressive exclusion

  1. Impacto do algodoeiro Bt na dinâmica populacional do pulgão-do-algodoeiro em casa de vegetação Impact of Bt cotton on the population dynamics of the cotton aphid in greenhouse

    Directory of Open Access Journals (Sweden)

    Edison Ryoiti Sujii

    2008-10-01

    Full Text Available O objetivo deste trabalho foi desenvolver um protocolo experimental para avaliar o impacto do algodoeiro Bt na bionomia e na escolha de plantas para colonização pelo pulgão-do-algodoeiro (Aphis gossypii. A bionomia do pulgão foi avaliada em casa de vegetação com insetos criados em gaiolas individuais com plantas de algodão Bt, da variedade DP 404 BG (Bollgard, ou sua isolinha não transformada DP 4049. Gaiolas contendo vasos com plantas de algodoeiro Bt e não-Bt foram usadas como arena de escolha, para a avaliação de preferência de adultos alados. O período pré-reprodutivo e reprodutivo, a longevidade, a curva de sobrevivência, a produção de prole total e diária por fêmea e a curva acumulada de produção de prole da população não apresentaram diferenças significativas. Não foi observada diferença na escolha de plantas para colonização por indivíduos alados, o que indica taxas equivalentes de colonização nas populações iniciais. O algodoeiro Bt não afeta a dinâmica populacional de A. gossypii e não aumenta seu potencial de risco como praga.The objective of this work was to develop an experimental protocol to assess the impact of Bt cotton on bionomics and on plant choice for Aphis gossypii colonization. The bionomics of the cotton aphid was assessed in greenhouse with insects reared in individual cages containing Bt cotton plants of the variety DP 404 BG (Bollgard or its nontransformed isoline DP 4049. Cages with Bt cotton and non-Bt cotton were used as choosing arena for evaluation of winged adults preference. There was no significant difference for pre-reproduction period (immature phase, reproduction period, longevity, survivorship curve total and daily production of offspring by female, and curve of accumulated production of offspring by the population. There was no preference of colonization for any plant by winged adults, which indicates equivalent rates of colonization of the initial populations. Bt

  2. Soil nutrient additions increase invertebrate herbivore abundances, but not herbivory, across three grassland systems.

    Science.gov (United States)

    La Pierre, Kimberly J; Smith, Melinda D

    2016-02-01

    Resource availability may influence invertebrate communities, with important consequences for ecosystem function, such as biomass production. We assessed: (1) the effects of experimental soil nutrient additions on invertebrate abundances and feeding rates and (2) the resultant changes in the effects of invertebrates on aboveground plant biomass at three grassland sites spanning the North American Central Plains, across which plant tissue chemistry and biomass vary. Invertebrate communities and rates of herbivory were sampled within a long-term nutrient-addition experiment established at each site along the broad Central Plains precipitation gradient. Additionally, the effects of invertebrates on aboveground plant biomass were determined under ambient and elevated nutrient conditions. At the more mesic sites, invertebrate herbivore abundances increased and their per capita rate of herbivory decreased with nutrient additions. In contrast, at the semi-arid site where plant biomass is low and plant nutrient concentrations are high, invertebrate herbivore abundances did not vary and per capita rates of herbivory increased with nutrient additions. No change in the effect of invertebrate herbivores on aboveground plant biomass was observed at any of the sites. In sum, nutrient additions induced shifts in both plant biomass and leaf nutrient content, which altered invertebrate abundances and feeding rate. However, due to the inverse relationship between changes in herbivore abundance and per capita rates of herbivory, nutrient additions did not alter the effect of invertebrates on aboveground biomass. Overall, we suggest that this inverse response of herbivore abundance and per capita feeding rate may buffer ecosystems against changes in invertebrate damage in response to fluctuations in nutrient levels. PMID:26474567

  3. A comparison of Bt transgene, hybrid background, water stress, and insect stress effects on corn leaf and ear injury and subsequent yield.

    Science.gov (United States)

    Brewer, Michael J; Odvody, Gary N; Anderson, Darwin J; Remmers, Jeffrey C

    2014-06-01

    Experimentally manipulated water and insect stresses were applied to field-grown corn with different Bacillus thuringiensis (Bt) transgenes and no Bt transgenes, and different nontransgenic hybrid backgrounds (2011 and 2012, Corpus Christi, TX). Differences in leaf injury, ear injury, and yield were detected among experimental factors and their interactions. Under high and low water stress, injury from noctuid larvae (Lepidoptera: Noctuidae) on leaves during vegetative growth (primarily from fall armyworm, Spodoptera frugiperda J.E. Smith) and on developing ears (primarily from corn earworm, Helicoverpa zea [Boddie]) was lowest on more recent releases of Bt hybrids (newer Bt hybrids) expressing Cry1A.105+Cry2Ab2 and Cry 3Bb1, compared with earlier Bt hybrids (older Bt hybrids) expressing Cry1Ab and Cry3Bb1 and non-Bt hybrids. High water stress led to increased leaf injury under substantial fall armyworm feeding pressure in 2011 (as high as 8.7 on a 1-9 scale of increasing injury). In contrast, ear injury by corn earworm (as high as 20 cm(2) of surface area of injury) was greater in low water stress conditions. Six hybrid backgrounds did not influence leaf injury, while ear injury differences across hybrid backgrounds were detected for non-Bt and older Bt hybrid versions. While newer Bt hybrids expressing Cry1A.105+Cry2Ab2 and Cry 3Bb1 had consistent low leaf injury and high yield and low but less consistent ear injury across six hybrid backgrounds, water stress was a key factor that influenced yield. Bt transgenes played a more variable and lesser role when interacting with water stress to affect yield. These results exemplify the interplay of water and insect stress with plant injury and yield, their interactions with Bt transgenes, and the importance of these interactions in considering strategies for Bt transgene use where water stress is common. PMID:24780114

  4. Lithium/polymer batteries. Safety approach of the BT-EDF-CEA project; Accumulateurs lithium/polymere. Demarche securite du projet BT-EDF-CEA

    Energy Technology Data Exchange (ETDEWEB)

    Lascaud, S.; Baudry, P. [Electricite de France, 77 - Moret sur Loing (France). Direction des Etudes et Recherches; Majastre, H. [Bollore Technologies, 29 - Quimper (France); Bloch, D. [CEAGrenoble, CEREM, 38 (France)

    1996-12-31

    The BT-EdF-CEA consortium for the development and the performance improvement of lithium/polymer batteries has carried out a safety analysis of the industrial risk and the risk for users linked with this new technology. The process chosen for the manufacturing of lithium/polymer batteries does not generate any particular risk of personnel or environmental contamination. Security tests have permitted to observe and analyze the behaviour of 4 Ah elements during thermal shocks, perforation and crushing, and during external short-circuit on 20 Ah elements. These tests demonstrate the great thermal stability and the excellent behaviour of batteries in the case of partial destruction. (J.S.) 2 refs.

  5. Molecular composition of leaves and stems of genetically modified Bt and near-isogenic non-Bt maize--characterization of lignin patterns.

    Science.gov (United States)

    Poerschmann, Juergen; Gathmann, Achim; Augustin, Juergen; Langer, Uwe; Górecki, Tadeusz

    2005-01-01

    Transformation of crops, including maize (Zea mays L.), with the cry1Ab gene from Bacillus thuringiensis to combat lepidopteran pests results in pleiotropic effects regarding lignin biosynthesis. Lignin patterns in stems and leaves of two genetically modified Bt-maize varieties (Novelis T and Valmont T) were studied along with their non-Bt near-isolines (Nobilis and Prelude, respectively). Molecular-level based thermochemolysis using tetramethylammonium hydroxide (TMAH) in combination with gas chromatography-mass spectrometry (GC-MS) was used to quantitate the total lignin contents and to identify monomeric lignin subunits including p-hydroxyphenyl (P), guaiacyl (G), and syringyl (S) moieties. The results were supplemented and confirmed by cupric oxide oxidation. The stems of the transgenic lines had higher concentrations of total lignin than the respective isogenic lines: Valmont T/Prelude by 18% and Novelis T/Nobilis by 28%. In contrast, differences in the total lignin concentration of leaves between the transgenic and the respective near-isogenic lines were marginal. There were significant modifications in the ratio of p-hydroxyphenyl/guaiacyl/syringyl molecular marker units of stem lignin between transgenic and isogenic lines. The guaiacyl units (in particular the G18 marker) accounted chiefly for the higher total lignin contents in the transgenic lines. The leaf lignin patterns did not show significant differences in molecular markers between isogenic and transgenic lines. TMAH-induced thermochemolysis--conducted in both the on-line and off-line modes--provided detailed information on the molecular composition of lignin, thus proving superior to the established "wet chemistry" methods of lignin determination. PMID:16091603

  6. Hominin reactions to herbivore distribution in the Lower Palaeolithic of the Southern Levant

    Science.gov (United States)

    Devès, Maud; Sturdy, Derek; Godet, Nan; King, Geoffrey C. P.; Bailey, Geoffrey N.

    2014-07-01

    We explore the relationship between the edaphic potential of soils and the mineral properties of the underlying geology as a means of mapping the differential productivity of different areas of the Pleistocene landscape for large herbivores. These factors strongly control the health of grazing animals irrespective of the particular types of vegetation growing on them, but they have generally been neglected in palaeoanthropological studies in favour of a more general emphasis on water and vegetation, which provide an incomplete picture. Taking the Carmel-Galilee-Golan region as an example, we show how an understanding of edaphic potential provides insight into how animals might have exploited the environment. In order to simplify the analysis, we concentrate on the Lower Palaeolithic period and the very large animals that dominate the archaeofaunal assemblages of this period. Topography and the ability of soils to retain water also contribute to the differential productivity and accessibility of different regions and to patterns of seasonal movements of the animals, which are essential to ensure a supply of healthy fodder throughout the year, especially for large animals such as elephants, which require substantial regions of good grazing and browsing. Other animals migrating in groups have similar needs. The complex topography of the Southern Levant with frequent sudden and severe changes in gradient, and a wide variety of landforms including rocky outcrops, cliffs, gorges, and ridges, places major limits on these patterns of seasonal movements. We develop methods of mapping these variables, based on the geology and our substantial field experience, in order to create a framework of landscape variation that can be compared with the locations and contents of archaeological sites to suggest ways in which early hominins used the variable features of the landscape to target animal prey, and extend the analysis to the consideration of smaller mammals that were exploited

  7. Multi-state trials of Bt sweet corn varieties for control of the corn earworm (Lepidoptera: Noctuidae).

    Science.gov (United States)

    Shelton, A M; Olmstead, D L; Burkness, E C; Hutchison, W D; Dively, G; Welty, C; Sparks, A N

    2013-10-01

    Field tests in 2010-2011 were performed in New York, Minnesota, Maryland, Ohio, and Georgia to compare Bt sweet corn lines expressing Cry1A.105 + Cry2Ab2 and Cry1Ab with their non-Bt isolines, with and without the use of foliar insecticides. The primary insect pest in all locations during the trial years was Heliocoverpa zea (Boddie), which is becoming the most serious insect pest of sweet corn in the United States. At harvest, the ears were measured for marketability according to fresh market and processing standards. For fresh market and processing, least squares regression showed significant effects of protein expression, state, and insecticide frequency. There was a significant effect of year for fresh market but not for processing. The model also showed significant effects of H. zea per ear by protein expression. Sweet corn containing two genes (Cry1A.105 + Cry2Ab2) and a single gene (Cry1Ab) provided high marketability, and both Bt varieties significantly outperformed the traditional non-Bt isolines in nearly all cases regardless of insecticide application frequency. For pest suppression of H. zea, plants expressing Bt proteins consistently performed better than non-Bt isoline plants, even those sprayed at conventional insecticide frequencies. Where comparisons in the same state were made between Cry1A.105 + Cry2Ab2 and Cry1Ab plants for fresh market, the product expressing Cry1A.105 + Cry2Ab2 provided better protection and resulted in less variability in control. Overall, these results indicate Cry1A.105 + Cry2Ab2 and Cry1Ab plants are suitable for fresh market and processing corn production across a diversity of growing regions and years. Our results demonstrate that Bt sweet corn has the potential to significantly reduce the use of conventional insecticides against lepidopteran pests and, in turn, reduce occupational and environmental risks that arise from intensive insecticide use. PMID:24224259

  8. Molecular interactions between the specialist herbivore Manduca sexta (Lepidoptera, Sphingidae) and its natural host Nicotiana attenuata. III. Fatty acid-amino acid conjugates in herbivore oral secretions are necessary and sufficient for herbivore-specific plant responses.

    Science.gov (United States)

    Halitschke, R; Schittko, U; Pohnert, G; Boland, W; Baldwin, I T

    2001-02-01

    Feeding by the tobacco specialist Manduca sexta (Lepidoptera, Sphingidae) and application of larval oral secretions and regurgitant (R) to mechanical wounds are known to elicit: (a) a systemic release of mono- and sesquiterpenes, (b) a jasmonate burst, and (c) R-specific changes in transcript accumulation of putatively growth- and defense-related mRNAs in Nicotiana attenuata Torr. ex Wats. We identified several fatty acid-amino acid conjugates (FACs) in the R of M. sexta and the closely related species Manduca quinquemaculata which, when synthesized and applied to mechanical wounds at concentrations comparable with those found in R, elicited all three R-specific responses. Ion-exchange treatment of R, which removed all detectable FACs and free fatty acids (FAs), also removed all detectable activity. The biological activity of ion-exchanged R could be completely restored by the addition of synthetic FACs at R-equivalent concentrations, whereas the addition of FAs did not restore the biological activity of R. We conclude that the biological activity of R is not related to the supply of FAs to the octadecanoid cascade for endogenous jasmonate biosynthesis, but that FACs elicit the herbivore-specific responses by another mechanism and that the insect-produced modification of plant-derived FAs is necessary for the plant's recognition of this specialized herbivore. PMID:11161028

  9. Apparent digestibility coefficients and consumption of corn silage with and without Bt gene in sheep

    Directory of Open Access Journals (Sweden)

    Camila Memari Trava

    2012-12-01

    Full Text Available Corn silage is the most important preserved food for ruminants. The transgenic corn was inserted into the genetic code Bt gene (Bacillus thuringiensis that expresses a toxic protein to caterpillars pests of maize, reducing production costs. To evaluate the varieties of plant corn silage DKB and AG with or without the Bt gene on the voluntary intake of DM (g/day and apparent digestibility coefficients (CDA of nutrients in sheep, the experiment was conducted at the Institute of Animal Science Nova Odessa-SP. Were used 20 sheep and the experimental design was randomized blocks in scheme factorial type 2x2 (two varieties of plant corn to silage, with the presence or absence of Bt gene, with five animals per treatment. These animals were housed in metabolism cages, with collector and separator feces and urine for 21 days, comprising 8 days for diet adaptation and 7 days for determination of intake, followed by 6 days of collection of feces, to measure DMI (g/day, CDA DM, CP and NDF. Samples of feed offered, leftovers and feces were identified and placed in a circulating air oven maintained at 55°C to constant weight. The analyses were performed in Bromatological Analysis Laboratory of the Institute of Animal Science. To CTMS (g/day was interaction effect (p<0.05 than in the variety AG (779.36 was greater than DKB (637.52, because the DM content of the sheet AG (31.09 was superior to DKB (29.17. The AG (779.36 was higher than your counterpart isogenic without the gene (575.15 p<0.05. The DKB without the gene (637.52 did not differ (p>0.05 from your counterpart DKBBt with the gene (590.78. The lowest total DM intake in g/day was observed for varieties with Bt gene insertion (genetically modified organism - GMO and a possible explanation is the higher value of NDF in the silages of variety with the Bt gene in relation to their isogenic counterparts without the gene. The CDA, DM and NDF no had interaction effect between varieties factors and GMO (p>0

  10. Overcoming barriers to trust in agricultural biotechnology projects: a case study of Bt cowpea in Nigeria

    Directory of Open Access Journals (Sweden)

    Ezezika Obidimma C

    2012-11-01

    Full Text Available Abstract Background Nigeria, Africa’s most populous country, has been the world’s largest cowpea importer since 2004. The country is currently in the early phases of confined field trials for two genetically modified crops: Bacillus thuringiensis (Bt cowpea and nutritionally enhanced cassava (“BioCassava Plus”. Using the bio-safety guidelines process as a backdrop, we evaluate the role of trust in the operation of the Cowpea Productivity Improvement Project, which is an international agricultural biotechnology public-private partnership (PPP aimed at providing pest-resistant cowpea varieties to Nigerian farmers. Methods We reviewed the published literature and collected data through direct observations and semi-structured, face-to-face interviews. Data were analyzed based on emergent themes to create a comprehensive narrative on how trust is understood and built among the partners and with the community. Results Our findings highlight the importance of respecting mandates and eliminating conflicts of interest; holding community engagement initiatives early on; having on-going internal discussion and planning; and serving a locally-defined need. These four lessons could prove helpful to other agricultural biotechnology initiatives in which partners may face similar trust-related challenges. Conclusions Overcoming challenges to building trust requires concerted effort throughout all stages of project implementation. Currently, plans are being made to backcross the cowpea strain into a local variety in Nigeria. The development and adoption of the Bt cowpea seed hinges on the adoption of a National Biosafety Law in Nigeria. For countries that have decided to adopt biotech crops, the Nigerian cowpea experiment can be used as a model for other West African nations, and is actually applied as such in Ghana and Burkina Faso, interested in developing a Bt cowpea.

  11. Detection and characterization of cry1Ac transgene construct in Bt cotton: multiple polymerase chain reaction approach.

    Science.gov (United States)

    Singh, Chandra K; Ojha, Abhishek; Kachru, Devendra N

    2007-01-01

    To comply with international labeling regulations for genetically modified (GM) crops and food, and to enable proper identification of GM organisms (GMOs), effective methodologies and reliable approaches are needed. The spurious and unapproved GM planting has contributed to crop failures and commercial losses. To ensure effective and genuine GM cultivation, a methodology is needed to detect and identify the trait of interest and concurrently evaluate the structural and functional stability of the transgene insert. A multiple polymerase chain reaction (PCR) approach was developed for detection, identification, and gene stability confirmation of cry1Ac transgene construct in Bt cotton. As many as 9 samples of Bt cotton hybrid seeds comprising 3 approved Bt hybrids, MECH-12Bt, MECH-162Bt, MECH-184Bt, and a batch of 6 nonapproved Bt hybrids were tested. Initially, single standard PCR assays were run to amplify predominant GM DNA sequences (CaMV 35S promoter, nos terminator, and npt-II marker gene); a housekeeping gene, Gossypium hirsutum fiber-specific acyl carrier protein gene (acp1); a trait-specific transgene (cry1Ac); and a sequence of 7S 3' transcription terminator which specifically borders with 3' region of cry1Ac transgene cassette. The concurrent amplification of all sequences of the entire cassette was performed by 3 assays, duplex, triplex, and quadruplex multiplex PCR assays, under common assay conditions. The identity of amplicons was reconfirmed by restriction endonuclease digestion profile. The 2 distinct transgene cassettes, cry1Ac and npt-II, of the Bt cotton were amplified using the respective forward primer of promoter and reverse primer of terminator. The resultant amplicons were excised, eluted, and purified. The purified amplicons served as template for nested PCR assays. The nested PCR runs confirmed the transgene construct orientation and identity. The limit of detection as established by our assay for GM trait (cry1Ac) was 0.1%. This approach

  12. Fish, Benthic and Urchin Survey Data from Kahekili Herbivore Fisheries Management Area (HFMA), Maui since 2008 (NCEI Accession 0146683)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data are summary fish, benthic and urchin data from belt transect surveys conducted by the NOAA Coral Reef Ecosystem Program within the Kahekili Herbivore Fisheries...

  13. Parallel evolution in an invasive plant: effect of herbivores on competitive ability and regrowth of Jacobaea vulgaris.

    Science.gov (United States)

    Lin, Tiantian; Klinkhamer, Peter G L; Vrieling, Klaas

    2015-07-01

    A shift in the composition of the herbivore guild in the invasive range is expected to select for plants with a higher competitive ability, a lower regrowth capacity and a lower investment in defence. We show here that parallel evolution took place in three geographically distinct invasive regions that differed significantly in climatic conditions. This makes it most likely that indeed the shifts in herbivore guilds were causal to the evolutionary changes. We studied competitive ability and regrowth of invasive and native Jacobaea vulgaris using an intraspecific competition set-up with and without herbivory. Without herbivores invasive genotypes have a higher competitive ability than native genotypes. The invasive genotypes were less preferred by the generalist Mamestra brassicae but more preferred by the specialist Tyria jacobaeae, consequently their competitive ability was significantly increased by the first and reduced by the latter. Invasive genotypes showed a lower regrowth ability in both herbivore treatments. PMID:25958781

  14. A challenge for the seed mixture refuge strategy in Bt maize: impact of cross-pollination on an ear-feeding pest, corn earworm.

    Directory of Open Access Journals (Sweden)

    Fei Yang

    Full Text Available To counter the threat of insect resistance, Bacillus thuringiensis (Bt maize growers in the U.S. are required to plant structured non-Bt maize refuges. Concerns with refuge compliance led to the introduction of seed mixtures, also called RIB (refuge-in-the-bag, as an alternative approach for implementing refuge for Bt maize products in the U.S. Maize Belt. A major concern in RIB is cross-pollination of maize hybrids that can cause Bt proteins to be present in refuge maize kernels and negatively affect refuge insects. Here we show that a mixed planting of 5% nonBt and 95% Bt maize containing the SmartStax traits expressing Cry1A.105, Cry2Ab2 and Cry1F did not provide an effective refuge for an important above-ground ear-feeding pest, the corn earworm, Helicoverpa zea (Boddie. Cross-pollination in RIB caused a majority (>90% of refuge kernels to express ≥ one Bt protein. The contamination of Bt proteins in the refuge ears reduced neonate-to-adult survivorship of H. zea to only 4.6%, a reduction of 88.1% relative to larvae feeding on ears of pure non-Bt maize plantings. In addition, the limited survivors on refuge ears had lower pupal mass and took longer to develop to adults.

  15. Scientific Opinion updating the risk assessment conclusions and risk management recommendations on the genetically modified insect resistant maize Bt11

    Directory of Open Access Journals (Sweden)

    EFSA Panel on Genetically Modified Organisms (GMO

    2012-12-01

    Full Text Available Following a request from the European Commission, the Panel on Genetically Modified Organisms of the European Food Safety Authority (EFSA GMO Panel compiled its previous risk assessment conclusions and risk management recommendations on the genetically modified insect resistant maize Bt11, and considered their validity in the light of new relevant scientific publications published from 2005 onwards. Following a search of the scientific literature published between 2005 and October 2012, the EFSA GMO Panel identified 287 peer-reviewed publications containing evidence specific to the risk assessment and/or management of maize Bt11, of which 270 publications were previously discussed and cited in relevant GM maize-related applications and/or the numerous EFSA GMO Panel scientific outputs. From the remaining 17 publications, three were relevant for the food and feed safety assessment, and 14 for the environmental risk assessment and/or risk management of maize Bt11. None of these publications reported new information that would invalidate the previous conclusions on the safety of maize Bt11 made by the EFSA GMO Panel. Therefore, the EFSA GMO Panel considers that its previous risk assessment conclusions on maize Bt11, as well as its previous recommendations on risk mitigation measures and monitoring, remain valid and applicable.

  16. Genetically modified rice Bt-Shanyou63 expressing Cry1Ab/c protein does not harm Daphnia magna.

    Science.gov (United States)

    Zhang, Li; Guo, Ruqing; Fang, Zhixiang; Liu, Biao

    2016-10-01

    The genetically modified (GM) rice Bt-ShanYou63 (Bt-SY63) received an official biosafety certificate while its safety remained in dispute. In a lifelong study, Daphnia magna were experimentally fed a basal diet of rice flours from Bt-SY63 or its parental rice ShanYou63 (SY63) at concentrations of 0.2mg, 0.3mg, or 0.4mgC (per individual per day). Overall the survival, body size, and reproduction of the animals were comparable between Bt-SY63 and ShanYou63.. The results showed that no significant differences were observed in growth and reproduction parameters between D. magna fed GM and non-GM flour and no dose-related changes occurred in all the values. Based on the different parameters assessed, the GM rice Bt-SY63 is a safe food source for D. magna that does not differ in quality from non-GM rice. PMID:27322607

  17. [Microbial diversity in rhizosphere soil of transgenic Bt rice based on the characterization of phospholipids fatty acids].

    Science.gov (United States)

    Liu, Wei; Wang, Shu-tao; Chen, Ying-xu; Wu, Wei-xiang; Wang, Jing

    2011-03-01

    Taking non-transgenic parental rice as the control, and by using 13C pulse-chase labeling method coupled with phospholipid fatty acid (PLFA) analysis, this paper studied the effects of transgenic Bt rice on the microbial diversity in rhizosphere soil. The results showed that in the rhizosphere soils of transgenic Bt rice and its non-transgenic parent, saturated PLFAs and branched PLFAs were the main, followed by monounsaturated PLFAs, and polyunsaturated PLFAs. A significantly lower amount of Gram-positive bacterial PLFAs and a higher amount of Gram-negative bacterial PLFAs were observed in the rhizosphere soil of transgenic Bt rice at its seedling, booting, and heading stages, as compared with the control. In the whole growth period of rice, transgenic Bt gene had no significant effects on the fungal and actinomycete PLFAs in rhizosphere soil, and no significant difference was observed in the rhizosphere soil 13C-PLFA content between transgenic Bt rice and its non-transgenic parent. These findings indicated that the insertion of exogenous cry1Ab gene into rice only had temporary effects on the microbial community composition in the rhizosphere soil of rice. PMID:21657031

  18. Cellular penetration and nuclear importation properties of {sup 111}In-labeled and {sup 123}I-labeled HIV-1 tat peptide immunoconjugates in BT-474 human breast cancer cells

    Energy Technology Data Exchange (ETDEWEB)

    Cornelissen, Bart [Division of Nuclear Medicine, University Health Network, Toronto, ON, M5S 3M2 (Canada); Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, M5S 3M2 (Canada); Hu, Meiduo [Division of Nuclear Medicine, University Health Network, Toronto, ON, M5S 3M2 (Canada); Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, M5S 3M2 (Canada); McLarty, Kristin [Division of Nuclear Medicine, University Health Network, Toronto, ON, M5S 3M2 (Canada); Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, M5S 3M2 (Canada); Costantini, Dan [Division of Nuclear Medicine, University Health Network, Toronto, ON, M5S 3M2 (Canada); Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, M5S 3M2 (Canada); Reilly, Raymond M. [Division of Nuclear Medicine, University Health Network, Toronto, ON, M5S 3M2 (Canada) and Department of Medical Imaging, University of Toronto, Toronto, ON, M5S 3M2 (Canada) and Department of Pharmaceutical Sciences, University of Toronto, Toronto, ON, M5S 3M2 (Canada) and Toronto General Research Institute, University Health Network, Toronto, ON, M5S 3M2 (Canada)]. E-mail: raymond.reilly@utoronto.ca

    2007-01-15

    Introduction: Our objective was to compare the cell penetration and nuclear importation properties of {sup 111}In-labeled and {sup 123}I-labeled immunoconjugates (ICs) composed of 16-mer peptides (GRKKRRQRRRPPQGYG) derived from HIV-1 transactivator of transcription (tat) protein and anti-mouse IgG (mIgG) in BT-474 breast cancer (BC) cells. Methods: [{sup 111}In]tat ICs were constructed by site-specific conjugation of tat peptides to NaIO{sub 4} {sup -}-oxidized carbohydrates in the Fc domain of diethylenetriaminepentaacetic-acid-modified anti-mIgG antibodies. Immunoreactivity against mIgG was assessed in a competition assay. The kinetics of the accumulation of [{sup 111}In]anti-mIgG-tat IC and [{sup 123}I]anti-mIgG-tat ICs in BT-474 cells and the elimination of radioactivity from cells, cytoplasm or nuclei were determined. The effects of excess tat peptides or NH{sub 4}Cl (an inhibitor of endosomal acidification) on cellular uptake and nuclear importation of [{sup 111}In]anti-mIgG-tat were measured. Results: [{sup 111}In]anti-mIgG-tat was >97% radiochemically pure and exhibited preserved immunoreactivity with mIgG epitopes. [{sup 123}I]Anti-mIgG-tat penetrated BT-474 cells more rapidly than [{sup 111}In]anti-mIgG-tat ICs and achieved a 1.5-fold to a 2-fold higher uptake in cells and nuclei. Cell penetration and nuclear uptake of [{sup 111}In]anti-mIgG-tat were inhibited by excess tat peptides and NH{sub 4}Cl. Elimination of radioactivity from BT-474 cells and nuclei was more rapid and complete for {sup 123}I-labeled than for {sup 111}In-labeled anti-mIgG-tat ICs. Conclusion: Tat peptides derived from HIV-1 tat protein promoted the penetration and nuclear uptake of radioactivity following the incubation of {sup 111}In-labeled and {sup 123}I-labeled anti-mIgG antibodies with BT-474 human BC cells. {sup 111}In-labeled tat ICs are feasible for inserting radionuclides into cancer cells with potential for targeting intracellular and, particularly, nuclear epitopes for

  19. Rates and modes of body size evolution in early carnivores and herbivores: a case study from Captorhinidae

    OpenAIRE

    Brocklehurst, Neil

    2016-01-01

    Body size is an extremely important characteristic, impacting on a variety of ecological and life-history traits. It is therefore important to understand the factors which may affect its evolution, and diet has attracted much interest in this context. A recent study which examined the evolution of the earliest terrestrial herbivores in the Late Carboniferous and Early Permian concluded that in the four herbivorous clades examined there was a trend towards increased body size, and that this in...

  20. The problem of maintaining large herbivores in small conservation areas: deterioration of the grassveld in the Addo Elephant National Park

    OpenAIRE

    P. Novellie; A.J Hall-Martin; Joubert, D

    1991-01-01

    Changes in vegetation cover and species composition in a grassland community during a six year period are reported. The grass Themeda triandra and the dwarf shrub Helichrysum rosum decreased in abundance, whereas the grass Eragrostis obtusa increased. Comparison of grazed plots with fenced plots revealed large herbivores were responsible for the increase in abundance ofE. obtusa. The abundance of T. triandra was influenced by large herbivores, but rainfall fluctuations apparently also played ...