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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

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    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.

  2. Combined influence of Bt rice and rice dwarf virus on biological parameters of a non-target herbivore, Nephotettix cincticeps (Uhler) (Hemiptera: Cicadellidae).

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    Wang, Qianjin; Han, Naishun; Dang, Cong; Lu, Zengbin; Wang, Fang; Yao, Hongwei; Peng, Yufa; Stanley, David; Ye, Gongyin

    2017-01-01

    The advent of genetically modified (GM) Bt rice creates the possibility of interactions among Bt crops, crop pathogens and non-target herbivores. In particular, information on how pathogen-infected Bt-expressing plants will influence non-target herbivores is necessary to predict the sustainability of GM cropping systems. Laboratory bioassays were conducted to evaluate the potential combined impacts of rice dwarf virus (RDV) and two Bt rice lines, T1C-19 (Cry1C) and T2A-1 (Cry2A), on non-target green rice leafhopper (GRLH), Nephotettix cincticeps (Uhler) (Hemiptera: Cicadellidae). In the first experiment, GRLHs feeding preference tests on Bt rice lines compared to a parental control rice line, MH63, were conducted. As rice plants were uninfected with RDV, GRLHs generally preferred the control MH63 line over the two Bt lines during the initial 8 h, with no significant preference during the following 64 h. As rice plants were infected with RDV, there were no clear preferences between the Bt rice lines and the control MH63 line. In the second experiment, we assessed the combined influence of RDV-infection status and Bt rice lines on GRLH biological parameters. Egg duration, adult weights, and male adult longevity were significantly affected on RDV-infected Bt rice. Other parameters, egg hatching rate, nymph survival and fecundity were not significantly influenced. We infer that interaction effect among two testing Bt rice lines and RDV will not lead to enlarged pest populations, thus demonstrating that growing these two Bt rice lines will poses negligible risk to GRLH in sustainable rice agroecosystems. Long-term field experiments to monitor the population dynamics of GRLHs at large scale need to be carried out to confirm the current results.

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

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    Wolfenbarger, L LaReesa; Naranjo, Steven E; Lundgren, Jonathan G; Bitzer, Royce J; Watrud, Lidia S

    2008-05-07

    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. 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. 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 provide researchers with information to design more robust experiments and will inform the

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

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    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

  5. Assessing Potential Impact of Bt Eggplants on Non-Target Arthropods in the Philippines.

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    Mario V Navasero

    Full Text Available Studies on potential adverse effects of genetically engineered crops are part of an environmental risk assessment that is required prior to the commercial release of these crops. Of particular concern are non-target organisms (NTOs that provide important ecosystem services. Here, we report on studies conducted in the Philippines over three cropping seasons with Bt eggplants expressing Cry1Ac for control of the eggplant fruit and shoot borer (EFSB, Leucinodes orbonalis, to examine potential effects on field abundance, community composition, structure and biodiversity of NTO's, particularly non-target arthropod (NTA communities. We document that many arthropod taxa are associated with Bt eggplants and their non-Bt comparators and that the number of taxa and their densities varied within season and across trials. However, we found few significant differences in seasonal mean densities of arthropod taxa between Bt and non-Bt eggplants. As expected, a lower abundance of lepidopteran pests was detected in Bt eggplants. Higher abundance of a few non-target herbivores was detected in non-Bt eggplants as were a few non-target beneficials that might control them. Principal Response Curve (PRC analyses showed no statistically significant impact of Bt eggplants on overall arthropod communities through time in any season. Furthermore, we found no significant adverse impacts of Bt eggplants on species abundance, diversity and community dynamics, particularly for beneficial NTAs. These results support our previous studies documenting that Bt eggplants can effectively and selectively control the main pest of eggplant in Asia, the EFSB. The present study adds that it can do so without adverse effects on NTAs. Thus, Bt eggplants can be a foundational component for controlling EFSB in an Integrated Pest Management (IPM program and dramatically reduce dependence on conventional insecticides.

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

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    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.

  7. Effects of Bacillus thuringiensis on non-target herbivore and natural enemy assemblages in tropical irrigated rice.

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    Schoenly, Kenneth G; Cohen, Michael B; Barrion, Alberto T; Zhang, Wenjun; Gaolach, Bradley; Viajante, Vicente D

    2003-01-01

    Endotoxins from Bacillus thuringiensis (Bt) produced in transgenic pest-resistant Bt crops are generally not toxic to predatory and parasitic arthropods. However, elimination of Bt-susceptible prey and hosts in Bt crops could reduce predator and parasitoid abundance and thereby disrupt biological control of other herbivorous pests. Here we report results of a field study evaluating the effects of Bt sprays on non-target terrestrial herbivore and natural enemy assemblages from three rice (Oryza sativa L.) fields on Luzon Island, Philippines. Because of restrictions on field-testing of transgenic rice, Bt sprays were used to remove foliage-feeding lepidopteran larvae that would be targeted by Bt rice. Data from a 546-taxa Philippines-wide food web, matched abundance plots, species accumulation curves, time-series analysis, and ecostatistical tests for species richness and ranked abundance were used to compare different subsets of non-target herbivores, predators, and parasitoids in Bt sprayed and water-sprayed (control) plots. For whole communities of terrestrial predators and parasitoids, Bt sprays altered parasitoid richness in 3 of 3 sites and predator richness in 1 of 3 sites, as measured by rarefaction (in half of these cases, richness was greater in Bt plots), while Spearman tests on ranked abundances showed that correlations, although significantly positive between all treatment pairs, were stronger for predators than for parasitoids, suggesting that parasitoid complexes may have been more sensitive than predators to the effects of Bt sprays. Species accumulation curves and time-series analyses of population trends revealed no evidence that Bt sprays altered the overall buildup of predator or parasitoid communities or population trajectories of non-target herbivores (planthoppers and leafhoppers) nor was evidence found for bottom-up effects in total abundances of non-target species identified in the food web from the addition of spores in the Bt spray

  8. 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}

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    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

  9. Uptake of Bt endotoxins by nontarget herbivores and higher order arthropod predators: molecular evidence from a transgenic corn agroecosystem.

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    Harwood, James D; Wallin, William G; Obrycki, John J

    2005-08-01

    The planting of transgenic crops expressing Bacillus thuringiensis endotoxins is widespread throughout the world; the prolific increase in their application exposes nontarget organisms to toxins designed to control pests. To date, studies have focused upon the effects of Bt endotoxins on specific herbivores and detritivores, without consideration of their persistence within arthropod food webs. Here, we report the first quantitative field evaluation of levels of Bt endotoxin within nontarget herbivores and the uptake by higher order arthropods. Antibody-based assays indicated significant quantities of detectable Cry1Ab endotoxin within nontarget herbivores which feed on transgenic corn (including the corn flea beetle, Chaetocnema pulicaria, Japanese beetle, Popillia japonica and southern corn rootworm, Diabrotica undecimpunctata howardi). Furthermore, arthropod predators (Coccinellidae, Araneae, and Nabidae) collected from these agroecosystems also contained significant quantities of Cry1Ab endotoxin indicating its movement into higher trophic levels. This uptake by predators is likely to have occurred by direct feeding on plant material (in predators which are facultatively phytophagous) or the consumption of arthropod prey which contained these proteins. These data indicate that long-term exposure to insecticidal toxins occurs in the field. These levels of exposure should therefore be considered during future risk assessments of transgenic crops to nontarget herbivores and arthropod predators.

  10. Does Bt rice pose risks to non-target arthropods? Results of a meta-analysis in China

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    Transgenic Bt rice expressing the protoxin proteins derived from Bacillus thuringiensis Berliner (Bt) have been developed since 1989. Their ecological risks toward non-target organisms have been investigated. However, these studies were conducted individually, yielding inconsistent conclusions and u...

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

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

    2014-06-01

    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 be evaluated to assess potential negative effects on non-target organisms that provide important services to the ecosystem. Beneficial arthropods in sweetpotato production systems can include pollinators, decomposers, and predators and parasitoids of the target insect pest(s). Non-target arthropod species commonly found in sweetpotato fields that are related taxonomically to the target pests were identified through expert consultation and literature review in Uganda where Bt sweetpotato is expected to be initially evaluated. Results indicate the presence of few relevant non-target Coleopterans that could be affected by Coleopteran Bt sweetpotato varieties: ground, rove and ladybird beetles. These insects are important predators in sweetpotato fields. Additionally, honeybee (hymenoptera) is the main pollinator of sweetpotato and used for honey production. Numerous studies have shown that honeybees are unaffected by the Cry proteins currently deployed which are homologous to those of the weevil-resistant Bt sweetpotato. However, because of their feeding behaviour, Bt sweetpotato represents an extremely low hazard due to negligible exposure. Hence, we conclude that there is good evidence from literature and expert opinion that relevant NTOs in sweetpotato fields are unlikely to be affected by the introduction of Bt sweetpotato in Uganda.

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

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    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.

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

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    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...

  14. Inducibility of chemical defences by two chewing insect herbivores in pine trees is specific to targeted plant tissue, particular herbivore and defensive trait.

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    Moreira, Xoaquín; Lundborg, Lina; Zas, Rafael; Carrillo-Gavilán, Amparo; Borg-Karlson, Anna-Karin; Sampedro, Luis

    2013-10-01

    There is increasing evidence that plants can react to biotic aggressions with highly specific responses. However, few studies have attempted to jointly investigate whether the induction of plant defences is specific to a targeted plant tissue, plant species, herbivore identity, and defensive trait. Here we studied those factors contributing to the specificity of induced defensive responses in two economically important pine species against two chewing insect pest herbivores. Juvenile trees of Pinus pinaster and P. radiata were exposed to herbivory by two major pest threats, the large pine weevil Hylobius abietis (a bark-feeder) and the pine processionary caterpillar Thaumetopoea pityocampa (a folivore). We quantified in two tissues (stem and needles) the constitutive (control plants) and herbivore-induced concentrations of total polyphenolics, volatile and non-volatile resin, as well as the profile of mono- and sesquiterpenes. Stem chewing by the pine weevil increased concentrations of non-volatile resin, volatile monoterpenes, and (marginally) polyphenolics in stem tissues. Weevil feeding also increased the concentration of non-volatile resin and decreased polyphenolics in the needle tissues. Folivory by the caterpillar had no major effects on needle defensive chemistry, but a strong increase in the concentration of polyphenolics in the stem. Interestingly, we found similar patterns for all these above-reported effects in both pine species. These results offer convincing evidence that induced defences are highly specific and may vary depending on the targeted plant tissue, the insect herbivore causing the damage and the considered defensive compound. Copyright © 2013 Elsevier Ltd. All rights reserved.

  15. Can interactions between Bt proteins be predicted and how should effects on non-target organisms of GM crops with multiple Bt Proteins be assessed?

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    Schrijver, de, PAR; Clercq, de, Willem; Booij, K.; Maagd, de, R.A.; Frankenhuyzen, van, K.

    2014-01-01

    Genes expressing Bacillus thuringiensis (Bt) toxins have been incorporated into genetically modified (GM) plants to render these resistant to certain insect pests. Of particular interest have been the genes encoding Cry (Crystal) proteins, but also the gene encoding the vegetative insecticidal protein Vip3Aa has been incorporated into crop plants. Over the last decennium, GM events have been crossed through traditional breeding, resulting in stacked GM events expressing several Bt insect resi...

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

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    Xue, Kun; Deng, Su; Wang, RongJiang; Yan, FengMing; Xu, ChongRen

    2008-02-01

    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 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.

  17. Can interactions between Bt proteins be predicted and how should effects on non-target organisms of GM crops with multiple Bt Proteins be assessed?

    NARCIS (Netherlands)

    Schrijver, De A.; Clercq, de P.; Booij, K.; Maagd, de R.A.; Frankenhuyzen, van K.

    2014-01-01

    Genes expressing Bacillus thuringiensis (Bt) toxins have been incorporated into genetically modified (GM) plants to render these resistant to certain insect pests. Of particular interest have been the genes encoding Cry (Crystal) proteins, but also the gene encoding the vegetative insecticidal

  18. Expression of Bt-Cry3A in transgenic Populus alba × P. glandulosa and its effects on target and non-target pests and the arthropod community.

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    Zhang, Bingyu; Chen, Min; Zhang, Xiaofen; Luan, Hehui; Tian, Yingchuan; Su, Xiaohua

    2011-06-01

    During the growing seasons of 2006-2008, feeding tests and field studies were conducted in Beijing, China, to investigate the effects of transgenic Bacillus thuringiensis (Bt) poplar (BGA-5) expressing the Cry3A protein (0.0264-0.0326% of the total soluble protein) on target and non-target pests and the arthropod community. The effects of BGA-5 on the target pest Plagiodera versicolora (Coleoptera, Chrysomelidae) and a non-target pest Clostera anachoreta (Lepidoptera, Notodontidae), were assessed under laboratory conditions. Total mortality of P. versicolora larvae fed with BGA-5 leaves was significantly higher than that of the control (P < 0.05). The exuviation index of P. versicolora larvae fed with BGA-5 tended to be higher than that of CK, but it was not significantly different. The pupation rate and eclosion rate of the survived larvae fed with BGA-5 were lower than that of CK, but it was also not significantly different. Additionally, no significant differences were detected in the mortality, exuviations index, pupation rate, or eclosion rate of C. anachoreta fed with leaves of transgenic and non-transgenic poplars. Furthermore, the arthropod communities in the Bt poplar and CK field stands were similar, as indicated by four diversity indices (Berge-Parker index, Shannon-Wiener indices, evenness index, and Simpson's inverted index) and the Bray-Curtis index. Therefore, the Bt-Cry3A poplar decreased damage by the target pest (P. versicolora), had no effects on a non-target pest (C. anachoreta), and generally did not have any significant negative effect on the poplar arthropod community.

  19. Efeito de milho Bt sobre a entomofauna não alvo Side-effect of maize Bt on non-target arthropods

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    Filomena Martins

    2008-12-01

    Full Text Available Com o objectivo de verificar o impacte de milho Bt na fauna auxiliar de artrópodes, cultivaram-se, durante três anos (2002-2004, duas variedades de milho geneticamente modificadas (Compa CB e Elgina e as suas isogénicas (Dracma e Cecília. Os ensaios foram realizados no Núcleo de Ensaios e de Controlo do Escaroupim, no Ribatejo. As amostragens de artrópodes auxiliares foram realizadas quinzenalmente, durante o ciclo vegetativo da cultura, em quatro talhões, usando o método de aspiração. Não se encontraram diferenças na fauna auxiliar existente, entre as cultivares Bt e as suas isogénicas. Os artrópodes auxiliares mais abundantes, em qualquer dos anos e cultivares, foram os antocorídeos. Os himenópteros foram o segundo grupo mais representado, seguido das aranhas.In order to study the impact of transgenic maize on beneficial arthropods, two varieties of maize Bt (Compa CB and Elgina and the normal ones (Dracma and Cecília were sown. The trials were carried out, in Escaroupim, Ribatejo, from 2002 to 2004. The surveys were done by using a cordless hand vacuum machine, every 15 days, during the growing season. The results showed no significant differences between arthropods caught in maize Bt and the normal one. The beneficials with the highest numbers caught during the three years were Anthocoridae, Hymenoptera and Aranea were the first, second and third most representative groups of beneficial arthropods during the three years.

  20. Plant Glandular Trichomes as Targets for Breeding or Engineering of Resistance to Herbivores

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    Merijn R. Kant

    2012-12-01

    Full Text Available Glandular trichomes are specialized hairs found on the surface of about 30% of all vascular plants and are responsible for a significant portion of a plant’s secondary chemistry. Glandular trichomes are an important source of essential oils, i.e., natural fragrances or products that can be used by the pharmaceutical industry, although many of these substances have evolved to provide the plant with protection against herbivores and pathogens. The storage compartment of glandular trichomes usually is located on the tip of the hair and is part of the glandular cell, or cells, which are metabolically active. Trichomes and their exudates can be harvested relatively easily, and this has permitted a detailed study of their metabolites, as well as the genes and proteins responsible for them. This knowledge now assists classical breeding programs, as well as targeted genetic engineering, aimed to optimize trichome density and physiology to facilitate customization of essential oil production or to tune biocide activity to enhance crop protection. We will provide an overview of the metabolic diversity found within plant glandular trichomes, with the emphasis on those of the Solanaceae, and of the tools available to manipulate their activities for enhancing the plant’s resistance to pests.

  1. Aphid honeydew quality as a food source for parasitoids is maintained in Bt cotton.

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    Hagenbucher, Steffen; Wäckers, Felix L; Romeis, Jörg

    2014-01-01

    Bt-transgenic cotton has proven to be highly efficient in controlling key lepidopteran pests. One concern with the deployment of Bt cotton varieties is the potential proliferation of non-target pests. We previously showed that Bt cotton contained lower concentrations of insecticidal terpenoids as a result of reduced caterpillar damage, which benefited the aphid Aphis gossypii. It is thus important that non-target herbivores are under biological control in Bt cotton fields. The induction or lack of induction of terpenoids could also influence the quality of aphid honeydew, an important food source for beneficial insects. We therefore screened A. gossypii honeydew for cotton terpenoids, that are induced by caterpillars but not the aphids. We then tested the influence of induced insect-resistance of cotton on honeydew nutritional quality for the aphid parasitoid Lysiphlebus testaceipes and the whitefly parasitoid Eretmocerus eremicus. We detected the cotton terpenoids gossypol and hemigossypolone in A. gossypii honeydew. Although a feeding assay demonstrated that gossypol reduced the longevity of both parasitoid species in a non-linear, dose-dependent manner, the honeydew was capable of sustaining parasitoid longevity and reproduction. The level of caterpillar damage to Bt and non-Bt cotton had no impact on the quality of honeydew for the parasitoids.These results indicate that the nutritional quality of honeydew is maintained in Bt cotton and is not influenced by induced insect resistance.

  2. Aphid honeydew quality as a food source for parasitoids is maintained in Bt cotton.

    Directory of Open Access Journals (Sweden)

    Steffen Hagenbucher

    Full Text Available Bt-transgenic cotton has proven to be highly efficient in controlling key lepidopteran pests. One concern with the deployment of Bt cotton varieties is the potential proliferation of non-target pests. We previously showed that Bt cotton contained lower concentrations of insecticidal terpenoids as a result of reduced caterpillar damage, which benefited the aphid Aphis gossypii. It is thus important that non-target herbivores are under biological control in Bt cotton fields. The induction or lack of induction of terpenoids could also influence the quality of aphid honeydew, an important food source for beneficial insects. We therefore screened A. gossypii honeydew for cotton terpenoids, that are induced by caterpillars but not the aphids. We then tested the influence of induced insect-resistance of cotton on honeydew nutritional quality for the aphid parasitoid Lysiphlebus testaceipes and the whitefly parasitoid Eretmocerus eremicus. We detected the cotton terpenoids gossypol and hemigossypolone in A. gossypii honeydew. Although a feeding assay demonstrated that gossypol reduced the longevity of both parasitoid species in a non-linear, dose-dependent manner, the honeydew was capable of sustaining parasitoid longevity and reproduction. The level of caterpillar damage to Bt and non-Bt cotton had no impact on the quality of honeydew for the parasitoids.These results indicate that the nutritional quality of honeydew is maintained in Bt cotton and is not influenced by induced insect resistance.

  3. Target and nontarget effects of novel "triple-stacked" Bt-transgenic cotton 1: canopy arthropod communities.

    Science.gov (United States)

    Whitehouse, M E A; Wilson, L J; Davies, A P; Cross, D; Goldsmith, P; Thompson, A; Harden, S; Baker, G

    2014-02-01

    Transgenic cotton varieties (Bollgard II) expressing two proteins (Cry1Ac and Cry2Ab) from Bacillus thuringiensis (Bt) have been widely adopted in Australia to control larvae of Helicoverpa. A triple-stacked Bt-transgenic cotton producing Cry1Ac, Cry2Ab, and Vip3A proteins (Genuity Bollgard III) is being developed to reduce the chance that Helicoverpa will develop resistance to the Bt proteins. Before its introduction, nontarget effects on the agro-ecosystem need to be evaluated under field conditions. By using beatsheet and suction sampling methods, we compared the invertebrate communities of unsprayed non-Bt-cotton, Bollgard II, and Bollgard III in five experiments across three sites in Australia. We found significant differences between invertebrate communities of non-Bt and Bt (Bollgard II and Bollgard III) cotton only in experiments where lepidopteran larval abundance was high. In beatsheet samples where lepidopterans were absent (Bt crops), organisms associated with flowers and bolls in Bt-cotton were more abundant. In suction samples, where Lepidoptera were present (i.e., in non-Bt-cotton), organisms associated with damaged plant tissue and frass were more common. Hence in our study, Bt- and non-Bt-cotton communities only differed when sufficient lepidopteran larvae were present to exert both direct and indirect effects on species assemblages. There was no overall significant difference between Bollgard II and III communities, despite the addition of the Vip gene in Bollgard III. Consequently, the use of Bollgard III in Australian cotton provides additional protection against the development of resistance by Helicoverpa to Bt toxins, while having no additional effect on cotton invertebrate communities.

  4. Comparing Gene Expression Profiles Between Bt and non-Bt Rice in Response to Brown Planthopper Infestation.

    Science.gov (United States)

    Wang, Fang; Ning, Duo; Chen, Yang; Dang, Cong; Han, Nai-Shun; Liu, Yu'e; Ye, Gong-Yin

    2015-01-01

    Bt proteins are the most widely used insecticidal proteins in transgenic crops for improving insect resistance. We previously observed longer nymphal developmental duration and lower fecundity in brown planthopper (BPH) fed on Bt rice line KMD2, although Bt insecticidal protein Cry1Ab could rarely concentrate in this non-target rice pest. In the present study, we performed microarray analysis in an effort to detect Bt-independent variation, which might render Bt rice more defensive and/or less nutritious to BPH. We detected 3834 and 3273 differentially expressed probe-sets in response to BPH infestation in non-Bt parent Xiushui 11 and Bt rice KMD2, respectively, only 439 of which showed significant differences in expression between rice lines. Our analysis revealed a shift from growth to defense responses in response to BPH infestation, which was also detected in many other studies of plants suffering biotic and abiotic stresses. Chlorophyll biosynthesis and basic metabolism pathways were inhibited in response to infestation. IAA and GA levels decreased as a result of the repression of biosynthesis-related genes or the induction of inactivation-related genes. In accordance with these observations, a number of IAA-, GA-, BR-signaling genes were downregulated in response to BPH. Thus, the growth of rice plants under BPH attack was reduced and defense related hormone signaling like JA, SA and ET were activated. In addition, growth-related hormone signaling pathways, such as GA, BR, and auxin signaling pathways, as well as ABA, were also found to be involved in BPH-induced defense. On the other side, 51 probe-sets (represented 50 genes) that most likely contribute to the impact of Bt rice on BPH were identified, including three early nodulin genes, four lipid metabolic genes, 14 stress response genes, three TF genes and genes with other functions. Two transcription factor genes, bHLH and MYB, together with lipid transfer protein genes LTPL65 and early nodulin gene ENOD

  5. Comparing gene expression profiles between Bt and non-Bt rice in response to brown planthopper infestation

    Directory of Open Access Journals (Sweden)

    Fang eWang

    2015-12-01

    Full Text Available Bt proteins are the most widely used insecticidal proteins in transgenic crops for improving insect resistance. We previously observed longer nymphal developmental duration and lower fecundity in brown planthopper (BPH fed on Bt rice line KMD2, although Bt insecticidal protein Cry1Ab could rarely concentrate in this non-target rice pest. In the present study, we performed microarray analysis in an effort to detect Bt-independent variation, which might render Bt rice more defensive and/or less nutritious to BPH. We detected 3,834 and 3,273 differentially expressed probe-sets in response to BPH infestation in non-Bt parent Xiushui 11 and Bt rice KMD2, respectively, only 439 of which showed significant differences in expression between rice lines. Our analysis revealed a shift from growth to defense responses in response to BPH infestation, which was also detected in many other studies of plants suffering biotic and abiotic stresses. Chlorophyll biosynthesis and basic metabolism pathways were inhibited in response to infestation. IAA and GA levels decreased as a result of the repression of biosynthesis-related genes or the induction of inactivation-related genes. In accordance with these observations, a number of IAA-, GA-, BR-signaling genes were downregulated in response to BPH. Thus, the growth of rice plants under BPH attack was reduced and defense related hormone signaling like JA, SA and ET were activated. In addition, growth-related hormone signaling pathways, such as GA, BR and auxin signaling pathways, as well as ABA, were also found to be involved in BPH-induced defense. On the other side, 51 probe-sets (represented 50 genes that most likely contribute to the impact of Bt rice on BPH were identified, including three early nodulin genes, four lipid metabolic genes, 14 stress response genes, three TF genes and genes with other functions. Two transcription factor genes, bHLH and MYB, together with lipid transfer protein genes LTPL65 and

  6. A mathematical model of exposure of non-target Lepidoptera to Bt-maize pollen expressing Cry1Ab within Europe

    Science.gov (United States)

    Perry, J. N.; Devos, Y.; Arpaia, S.; Bartsch, D.; Gathmann, A.; Hails, R. S.; Kiss, J.; Lheureux, K.; Manachini, B.; Mestdagh, S.; Neemann, G.; Ortego, F.; Schiemann, J.; Sweet, J. B.

    2010-01-01

    Genetically modified (GM) maize MON810 expresses a Cry1Ab insecticidal protein, derived from Bacillus thuringiensis (Bt), toxic to lepidopteran target pests such as Ostrinia nubilalis. An environmental risk to non-target Lepidoptera from this GM crop is exposure to harmful amounts of Bt-containing pollen deposited on host plants in or near MON810 fields. An 11-parameter mathematical model analysed exposure of larvae of three non-target species: the butterflies Inachis io (L.), Vanessa atalanta (L.) and moth Plutella xylostella (L.), in 11 representative maize cultivation regions in four European countries. A mortality–dose relationship was integrated with a dose–distance relationship to estimate mortality both within the maize MON810 crop and within the field margin at varying distances from the crop edge. Mortality estimates were adjusted to allow for physical effects; the lack of temporal coincidence between the susceptible larval stage concerned and the period over which maize MON810 pollen is shed; and seven further parameters concerned with maize agronomy and host-plant ecology. Sublethal effects were estimated and allowance made for aggregated pollen deposition. Estimated environmental impact was low: in all regions, the calculated mortality rate for worst-case scenarios was less than one individual in every 1572 for the butterflies and one in 392 for the moth. PMID:20053648

  7. Effect of Bt genetic engineering on indirect defense in cotton via a tritrophic interaction.

    Science.gov (United States)

    Moraes, Maria Carolina Blassioli; Laumann, Raul Alberto; Aquino, Michely Ferreira Santos; Paula, Débora Pires; Borges, Miguel

    2011-02-01

    We present a tritrophic analysis of the potential non-intended pleiotropic effects of cry1Ac gene derived from Bacillus thurigiensis (Bt) insertion in cotton (DeltaPine 404 Bt Bollgard® variety) on the emission of herbivore induced volatile compounds and on the attraction of the egg parasitoid Trichogramma pretisoum (Hymenoptera: Trichogrammatidae). Both the herbivore damaged Bt variety and its non-Bt isoline (DeltaPine DP4049 variety) produced volatiles in higher quantity when compared to undamaged plants and significantly attracted the egg parasitoids (T. pretiosum) when compared to undamaged plants. However, Trichogramma pretiosum did not differentiate between the transgenic and nontransgenic varieties, suggesting that the ratios between the compounds released by herbivory damaged -Bt cotton and herbivory damaged-non Bt cotton did not change significantly. Finally, no detrimental effect of the Bt genetic engineering was detected related to the volatile compounds released by Bollgard cotton on the behavior of the natural enemy studied.

  8. Short-term assessment of bt maize on non-target arthropods in Brazil Avaliação do efeito de milho bt sobre artrópodos não alvo no Brasil

    Directory of Open Access Journals (Sweden)

    Odair Aparecido Fernandes

    2007-06-01

    Full Text Available Although not yet available for cultivation in Brazil, the effect of Bt maize hybrids on natural enemies and soil dwelling arthropods should be assessed prior to its release to growers. Trials were carried out during one growing season in two different locations with the genetically modified maize hybrids 7590-Bt11 and Avant-ICP4, comparing with their respective non-Bt isogenic hybrids. Arthropods were evaluated through direct observation on plants and pitfall traps. In general, no differences were observed between populations of earwig (Dermaptera: Forficulidae, lady beetles (Coleptera: Coccinellidae, minute pirate bug (Coleoptera: Anthocoridae, ground beetles (Carabidae, tiger beetles (Cicindelidae, and spiders (Araneae. There was no difference in egg parasitism of Helicoverpa zea (Boddie by Trichogramma sp. (Hymenoptera: Trichogrammatidae. Thus, Bt maize hybrids expressing insecticide proteins Cry1A(b and VIP 3A do not cause reduction of the main maize dweeling predators and parasitoids.Embora não haja cultivos comerciais de milho geneticamente modificado no Brasil, o efeito de híbridos de milho Bt sobre inimigos naturais e artrópodos de solo deve ser avaliado antes da liberação aos produtores. Assim, ensaios foram conduzidos durante uma safra em duas localidades. Os híbridos de milho modificado geneticamente 7590-Bt11 e Avant-ICP4 foram comparados com seus respectivos isogênicos não transgênicos. Os artrópodes foram avaliados através de observação direta nas plantas e armadilhas de alçapão. De modo geral, não se observaram diferenças entre as populações de tesourinha (Dermaptera: Forficulidae, joaninhas (Coleptera: Coccinellidae, percevejo-pirata (Coleoptera: Anthocoridae, carabídeos (Carabidae, cicindelídeos (Cicindelidae e aranhas (Araneae. Também não houve diferença no parasitismo de ovos de Helicoverpa zea (Boddie por Trichogramma sp. (Hymenoptera: Trichogrammatidae. Assim, milho geneticamente modificado

  9. 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.

  10. Nutrition affects insect susceptibility to Bt toxins

    Science.gov (United States)

    Deans, Carrie A.; Behmer, Spencer T.; Tessnow, Ashley E.; Tamez-Guerra, Patricia; Pusztai-Carey, Marianne; Sword, Gregory A.

    2017-01-01

    Pesticide resistance represents a major challenge to global food production. The spread of resistance alleles is the primary explanation for observations of reduced pesticide efficacy over time, but the potential for gene-by-environment interactions (plasticity) to mediate susceptibility has largely been overlooked. Here we show that nutrition is an environmental factor that affects susceptibility to Bt toxins. Protein and carbohydrates are two key macronutrients for insect herbivores, and the polyphagous pest Helicoverpa zea self-selects and performs best on diets that are protein-biased relative to carbohydrates. Despite this, most Bt bioassays employ carbohydrate-biased rearing diets. This study explored the effect of diet protein-carbohydrate content on H. zea susceptibility to Cry1Ac, a common Bt endotoxin. We detected a 100-fold increase in LC50 for larvae on optimal versus carbohydrate-biased diets, and significant diet-mediated variation in survival and performance when challenged with Cry1Ac. Our results suggest that Bt resistance bioassays that use ecologically- and physiologically-mismatched diets over-estimate susceptibility and under-estimate resistance.

  11. IT-BT convergence technology

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-12-15

    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.

  12. Bt rice expressing Cry2Aa does not cause direct detrimental effects on larvae of Chrysoperla sinica.

    Science.gov (United States)

    Li, Yunhe; Wang, Yuanyuan; Romeis, Jörg; Liu, Qingsong; Lin, Kejian; Chen, Xiuping; Peng, Yufa

    2013-11-01

    To assess the potential effects of Cry2Aa-expressing insect-resistant Bt rice on Chrysoperla sinica larvae, we conducted two tritrophic bioassays using a non-target (Laodelphax striatellus) and a target herbivore (Chilo suppressalis) as prey. None of the tested life-table parameters of C. sinica did differ when fed with L. striatellus nymphs reared on either Bt or control rice plants. Similarly, C. sinica larval survival and development were not affected when fed C. suppressalis larvae that were reared on Cry2Aa-contained artificial diet compared to those fed control diet. However, the 7-day larval weight was significantly decreased in the Bt treatment and none of the C. sinica larvae developed to the adult stage. To clarify whether the observed effects were due to the direct toxicity of Cry2Aa or prey-quality mediated, we conducted a dietary exposure assay in which the toxicity of Cry2Aa to C. sinica larvae was tested. Potassium arsenate (PA) was included as a positive control. None of the tested life-table parameters of C. sinica was adversely affected when fed Cry2Aa at 500 μg/ml sucrose solution. In contrast, C. sinica larvae were adversely affected by feeding on sucrose solution containing PA. In the feeding assays, exposure of C. sinica larvae to Cry2Aa was confirmed by ELISA. Our results demonstrate that C. sinica larvae are not sensitive to Cry2Aa at concentrations exceeding the levels that the larvae may encounter in Bt rice fields. Consequently the detrimental effects observed in the tritrophic studies using Bt rice-fed C. suppressalis as prey can be attributed to the decreased prey quality due to the sensitivity of C. suppressalis larvae to Cry2Aa.

  13. The halo effect: suppression of pink bollworm on non-Bt cotton by Bt cotton in China.

    Directory of Open Access Journals (Sweden)

    Peng Wan

    Full Text Available In some previously reported cases, transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt have suppressed insect pests not only in fields planted with such crops, but also regionally on host plants that do not produce Bt toxins. Here we used 16 years of field data to determine if Bt cotton caused this "halo effect" against pink bollworm (Pectinophora gossypiella in six provinces of the Yangtze River Valley of China. In this region, the percentage of cotton hectares planted with Bt cotton increased from 9% in 2000 to 94% in 2009 and 2010. We found that Bt cotton significantly decreased the population density of pink bollworm on non-Bt cotton, with net decreases of 91% for eggs and 95% for larvae on non-Bt cotton after 11 years of Bt cotton use. Insecticide sprays targeting pink bollworm and cotton bollworm (Helicoverpa armigera decreased by 69%. Previously reported evidence of the early stages of evolution of pink bollworm resistance to Bt cotton in China has raised concerns that if unchecked, such resistance could eventually diminish or eliminate the benefits of Bt cotton. The results reported here suggest that it might be possible to find a percentage of Bt cotton lower than the current level that causes sufficient regional pest suppression and reduces the risk of resistance.

  14. Stacked Bt maize and arthropod predators: exposure to insecticidal Cry proteins and potential hazards.

    Science.gov (United States)

    Svobodová, Zdeňka; Shu, Yinghua; Skoková Habuštová, Oxana; Romeis, Jörg; Meissle, Michael

    2017-07-26

    Genetically engineered (GE) crops with stacked insecticidal traits expose arthropods to multiple Cry proteins from Bacillus thuringiensis (Bt). One concern is that the different Cry proteins may interact and lead to unexpected adverse effects on non-target species. Bi- and tri-trophic experiments with SmartStax maize, herbivorous spider mites (Tetranychus urticae), aphids (Rhopalosiphum padi), predatory spiders (Phylloneta impressa), ladybeetles (Harmonia axyridis) and lacewings (Chrysoperla carnea) were conducted. Cry1A.105, Cry1F, Cry3Bb1 and Cry34Ab1 moved in a similar pattern through the arthropod food chain. By contrast, Cry2Ab2 had highest concentrations in maize leaves, but lowest in pollen, and lowest acquisition rates by herbivores and predators. While spider mites contained Cry protein concentrations exceeding the values in leaves (except Cry2Ab2), aphids contained only traces of some Cry protein. Predators contained lower concentrations than their food. Among the different predators, ladybeetle larvae showed higher concentrations than lacewing larvae and juvenile spiders. Acute effects of SmartStax maize on predator survival, development and weight were not observed. The study thus provides evidence that the different Cry proteins do not interact in a way that poses a risk to the investigated non-target species under controlled laboratory conditions. © 2017 The Author(s).

  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. Molecular and life-history effects of a natural toxin on herbivorous and non-target soil arthropods

    DEFF Research Database (Denmark)

    van Ommen Kloeke, A E Elaine; van Gestel, Cornelis A. M.; Styrishave, Bjarne

    2012-01-01

    -expression of especially stress-related genes and sugar metabolism. The regulation of a gene encoding a precursor of follistatin, furthermore, implied the inhibition of reproduction and may be an important molecular target that can be linked to the observed adverse effect of life-history traits.......-MS/MS for quantification. Half-lives, tested at four concentration levels in natural soil, were on average 16 h with biodegradation as the plausible main removal process. Regardless, toxic effects on reproduction were shown for F. candida and P. fimata, with EC50 values of around 11.5 nmol/g soil illustrating the toxic...

  17. Expression of Cry1Ab protein in a marker-free transgenic Bt rice line and its efficacy in controlling a target pest, Chilo suppressalis (Lepidoptera: Crambidae).

    Science.gov (United States)

    Wang, Yanan; Zhang, Lei; Li, Yunhe; Liu, Yanmin; Han, Lanzhi; Zhu, Zhen; Wang, Feng; Peng, Yufa

    2014-04-01

    A marker-free Bt transgenic rice line, mfb-MH86, was recently developed in China, which contains a cry1Ab gene driven by a ubiquitin promoter. This Bt gene confers resistance to a range of lepidopteran species, including the striped stem borer, Chilo suppressalis (Walker). The expression of Cry1Ab protein in mfb-MH86 leaves, stems and leaf sheaths (hereinafter referred to as stems), and roots was evaluated throughout the rice-growing season using an enzyme-linked immunosorbent assay. In addition, mfb-MH86 resistance to C. suppressalis, a major pest of rice, was evaluated in a laboratory bioassay with field-collected rice stems. Cry1Ab protein levels of mfb-MH86 were highest in leaves (9.71-34.09 μg/g dry weight [DW]), intermediate in stems (7.66-18.51 μg/g DW), and lowest in roots (1.95-13.40 μg/g DW). In all tissues, Cry1Ab levels in mfb-MH86 were higher in seedling and tillering stages than in subsequent growth stages. In the laboratory bioassay, mortality of C. suppressalis after 6 d of feeding on mfb-MH86 stems was 100% throughout the rice-growing season; mortality of C. suppressalis when feeding on stems of the nontransformed isoline, MH86, ranged from 15.0 to 38.3%. The results indicate that Cry1Ab protein levels in mfb-MH86 stems are sufficient to protect plants against C. suppressalis throughout the rice-growing season. Although our results are promising, further comprehensive evaluations of mfb-MH86, including field surveys, will be needed before commercial use.

  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. 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.

  20. Contrasting effects of large herbivore grazing on smaller herbivores

    NARCIS (Netherlands)

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

    2009-01-01

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

  1. 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. Copyright © 2016 Elsevier Inc. All rights reserved.

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

    Science.gov (United States)

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

    2013-02-01

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

  3. 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.

  4. 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.

  5. 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.

  6. Cross-generational feeding of Bt (Bacillus thuringiensis)-maize to zebrafish (Danio rerio) showed no adverse effects on the parental or offspring generations.

    Science.gov (United States)

    Sanden, Monica; Ornsrud, Robin; Sissener, Nini H; Jorgensen, Susanne; Gu, Jinni; Bakke, Anne Marie; Hemre, Gro-Ingunn

    2013-12-01

    In the present study, zebrafish (Danio rerio) were fed casein/gelatin-based diets containing either 19% Bt (Bacillus thuringiensis)-maize or its parental non-Bt (nBt)-maize control for two generations (F0: sixty fish; F1: forty-two to seventy fish per treatment). The study focused on growth and reproductive performance, liver CuZn superoxide dismutase (SOD) enzyme activity, gene transcript levels targeting important cellular pathways in the liver and mid-intestine, histomorphological evaluation of the intestine, differential leucocyte counts, offspring larva swimming activity and global DNA methylation in offspring embryos. No significant effects were observed in the parental generation. The offspring were either fed the same diets as those fed to their parents (Bt-Bt or nBt-nBt) or switched from the Bt diet to the nBt diet (Bt-nBt). The Bt-Bt offspring exhibited a significantly higher body mass increase, specific growth rate and feed utilisation than fish fed the nBt-nBt diet and/or fish fed the Bt-nBt diet. Liver and mid-intestinal gene transcript levels of CuZn SOD were significantly higher in fish fed the nBt-nBt diet than in those fed the Bt-Bt diet. Liver gene transcript levels of caspase 6 were significantly lower for the nBt-nBt group than for the Bt-Bt group. Overall, enhanced growth performance was observed in fish fed the Bt diet for two generations than in those fed the nBt diet for one and two generations. Effects observed on gene biomarkers for oxidative stress and the cell cycle (apoptosis) may be related to the contamination of nBt-maize with fumonisin B1 and aflatoxin B1. In conclusion, it is suggested that Bt-maize is as safe and nutritious as its nBt control when fed to zebrafish for two generations.

  7. Characterizing indirect prey-quality mediated effects of a Bt crop on predatory larvae of the green lacewing, Chrysoperla carnea.

    Science.gov (United States)

    Lawo, Nora C; Wäckers, Felix L; Romeis, Jörg

    2010-11-01

    There is increasing evidence that insecticidal transgenic crops can indirectly cause detrimental effects on arthropod predators or parasitoids when they prey on or parasitize sublethally affected herbivores. Our studies revealed that Chrysoperla carnea is negatively affected when fed Bt-susceptible but not Cry1Ac-resistant Helicoverpa armigera larvae that had fed Bt-transgenic cotton expressing Cry1Ac. This despite the fact that the predators ingested 3.5 times more Cry1Ac when consuming the resistant caterpillars. In order to detect potential differences in the nutrient composition of prey larvae, we evaluated the glycogen and lipid content plus the sugar and free amino acid content and composition of caterpillars fed non-Bt and Bt cotton. The only change in susceptible H. armigera larvae attributable to Bt cotton feeding were changes in sugar concentration and composition. In case of the Cry1Ac-resistant H. armigera strain, feeding on Bt cotton resulted in a reduced glycogen content in the caterpillars. The predators, however, appeared to compensate for the reduced carbohydrate content of the prey by increasing biomass uptake which caused an excess intake of the other analyzed nutritional compounds. Our study clearly proves that nutritional prey-quality factors other then the Bt protein underlie the observed negative effects when C. carnea larvae are fed with Bt cotton-fed prey. Possible factors were an altered sugar composition or fitness costs associated with the excess intake of other nutrients. Copyright 2010 Elsevier Ltd. All rights reserved.

  8. 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.

  9. Characteristics of a broad lytic spectrum endolysin from phage BtCS33 of Bacillus thuringiensis.

    Science.gov (United States)

    Yuan, Yihui; Peng, Qin; Gao, Meiying

    2012-12-19

    Endolysins produced by bacteriophages lyse bacteria, and are thus considered a novel type of antimicrobial agent. Several endolysins from Bacillus phages or prophages have previously been characterized and used to target Bacillus strains that cause disease in animals and humans. B. thuringiensis phage BtCS33 is a Siphoviridae family phage and its genome has been sequenced and analyzed. In the BtCS33 genome, orf18 was found to encode an endolysin protein (PlyBt33). Bioinformatic analyses showed that endolysin PlyBt33 was composed of two functional domains, the N-terminal catalytic domain and the C-terminal cell wall binding domain. In this study, the entire endolysin PlyBt33, and both the N- and C-termini,were expressed in Escherichia coli and then purified. The lytic activities of PlyBt33 and its N-terminus were tested on bacteria. Both regions exhibited lytic activity, although PlyBt33 showed a higher lytic activity than the N-terminus. PlyBt33 exhibited activity against all Bacillus strains tested from five different species, but was not active against Gram-negative bacteria. Optimal conditions for PlyBt33 reactivity were pH 9.0 and 50 °C. PlyBt33 showed high thermostability, with 40% of initial activity remaining following 1 h of treatment at 60 °C. The C-terminus of PlyBt33 bound to B. thuringiensis strain HD-73 and Bacillus subtilis strain 168. This cell wall binding domain might be novel, as its amino acid sequence showed little similarity to previously reported endolysins. PlyBt33 showed potential as a novel antimicrobial agent at a relatively high temperature and had a broad lytic spectrum within the Bacillus genus. The C-terminus of PlyBt33 might be a novel kind of cell wall binding domain.

  10. Characteristics of a broad lytic spectrum endolysin from phage BtCS33 of Bacillus thuringiensis

    Directory of Open Access Journals (Sweden)

    Yuan Yihui

    2012-12-01

    Full Text Available Abstract Background Endolysins produced by bacteriophages lyse bacteria, and are thus considered a novel type of antimicrobial agent. Several endolysins from Bacillus phages or prophages have previously been characterized and used to target Bacillus strains that cause disease in animals and humans. B. thuringiensis phage BtCS33 is a Siphoviridae family phage and its genome has been sequenced and analyzed. In the BtCS33 genome, orf18 was found to encode an endolysin protein (PlyBt33. Results Bioinformatic analyses showed that endolysin PlyBt33 was composed of two functional domains, the N-terminal catalytic domain and the C-terminal cell wall binding domain. In this study, the entire endolysin PlyBt33, and both the N- and C-termini,were expressed in Escherichia coli and then purified. The lytic activities of PlyBt33 and its N-terminus were tested on bacteria. Both regions exhibited lytic activity, although PlyBt33 showed a higher lytic activity than the N-terminus. PlyBt33 exhibited activity against all Bacillus strains tested from five different species, but was not active against Gram-negative bacteria. Optimal conditions for PlyBt33 reactivity were pH 9.0 and 50°C. PlyBt33 showed high thermostability, with 40% of initial activity remaining following 1 h of treatment at 60°C. The C-terminus of PlyBt33 bound to B. thuringiensis strain HD-73 and Bacillus subtilis strain 168. This cell wall binding domain might be novel, as its amino acid sequence showed little similarity to previously reported endolysins. Conclusions PlyBt33 showed potential as a novel antimicrobial agent at a relatively high temperature and had a broad lytic spectrum within the Bacillus genus. The C-terminus of PlyBt33 might be a novel kind of cell wall binding domain.

  11. Biochemical and molecular characterization of barley plastidial ADP-glucose transporter (HvBT1.

    Directory of Open Access Journals (Sweden)

    Atta Soliman

    Full Text Available In cereals, ADP-glucose transporter protein plays an important role in starch biosynthesis. It acts as a main gate for the transport of ADP-glucose, the main precursor for starch biosynthesis during grain filling, from the cytosol into the amyloplasts of endospermic cells. In this study, we have shed some light on the molecular and biochemical characteristics of barley plastidial ADP-glucose transporter, HvBT1. Phylogenetic analysis of several BT1 homologues revealed that BT1 homologues are divided into two distinct groups. The HvBT1 is assigned to the group that represents BT homologues from monocotyledonous species. Some members of this group mainly work as nucleotide sugar transporters. Southern blot analysis showed the presence of a single copy of HvBT1 in barley genome. Gene expression analysis indicated that HvBT1 is mainly expressed in endospermic cells during grain filling; however, low level of its expression was detected in the autotrophic tissues, suggesting the possible role of HvBT1 in autotrophic tissues. The cellular and subcellular localization of HvBT1 provided additional evidence that HvBT1 targets the amyloplast membrane of the endospermic cells. Biochemical characterization of HvBT1 using E. coli system revealed that HvBT1 is able to transport ADP-glucose into E. coli cells with an affinity of 614.5 µM and in counter exchange of ADP with an affinity of 334.7 µM. The study also showed that AMP is another possible exchange substrate. The effect of non-labeled ADP-glucose and ADP on the uptake rate of [α-32P] ADP-glucose indicated the substrate specificity of HvBT1 for ADP-glucose and ADP.

  12. Early detection of field-evolved resistance to Bt cotton in China: cotton bollworm and pink bollworm.

    Science.gov (United States)

    Tabashnik, Bruce E; Wu, Kongming; Wu, Yidong

    2012-07-01

    Transgenic crops producing Bacillus thuringiensis (Bt) toxins kill some major insect pests, but pests can evolve resistance and thereby reduce the effectiveness of such Bt crops. The main approach for slowing 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 cotton producing Bt toxin Cry1Ac, several 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. This strategy is designed for cotton bollworm (Helicoverpa armigera), which attacks many crops and is the primary target of Bt cotton in China, but it does not apply to pink bollworm (Pectinophora gossypiella), which feeds almost entirely on cotton in China. Here we review evidence of field-evolved resistance to Cry1Ac by cotton bollworm in northern China and by pink bollworm in the Yangtze River Valley of China. For both pests, results of laboratory diet bioassays reveal significantly decreased susceptibility of field populations to Cry1Ac, yet field control failures of Bt cotton have not been reported. The early detection of resistance summarized here may spur countermeasures such as planting Bt cotton that produces two or more distinct toxins, increased planting of non-Bt cotton, and integration of other management tactics together with Bt cotton. Copyright © 2012 Elsevier Inc. All rights reserved.

  13. Bt: One Option for Gypsy Moth Management

    Science.gov (United States)

    Deborah C. Mccullough; Leah S. Bauer

    2000-01-01

    Though the gypsy moth will never go away, you have a variety of options to help manage this pest during outbreaks. One option involves the use of Bt to protect tree foliage and reduce the annoyance caused by gypsy moth caterpillars during an outbreak. Bt or Btk refers to a microorganism called Bacillus Thuringeniesis var. kurstaki. Bt has been widely adopted for...

  14. 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 ...

  15. Modeling evolution of resistance of sugarcane borer (Lepidoptera: Crambidae) to transgenic Bt corn.

    Science.gov (United States)

    Kang, J; Huang, F; Onstad, D W

    2014-08-01

    Diatraea saccharalis (F.) (Lepidoptera: Crambidae) is a target pest of transgenic corn expressing Bacillus thuringiensis (Bt) protein, and the first evidence of resistance by D. saccharalis to Cry1Ab corn was detected in a field population in northeast Louisiana in 2004. We used a model of population dynamics and genetics of D. saccharalis to 1) study the effect of interfield dispersal, the first date that larvae enter diapause for overwintering, toxin mortality, the proportion of non-Bt corn in the corn patch, and the area of a crop patch on Bt resistance evolution; and 2) to identify gaps in empirical knowledge for managing D. saccharalis resistance to Bt corn. Increasing, the proportion of corn refuge did not always improve the durability of Bt corn if the landscape also contained sugarcane, sorghum, or rice. In the landscape, which consisted of 90% corn area, 5% sorghum area, and 5% rice area, the durability of single-protein Bt corn was 40 yr when the proportion of corn refuge was 0.2 but 16 yr when the proportion of corn refuge was 0.5. The Bt resistance evolution was sensitive to a change (from Julian date 260 to 272) in the first date larvae enter diapause for overwintering and moth movement. In the landscapes with Bt corn, non-Bt corn, sugarcane, sorghum, and rice, the evolution of Bt resistance accelerated when larvae entered diapause for overwintering early. Intermediate rates of moth movement delayed evolution of resistance more than either extremely low or high rates. This study suggested that heterogeneity in the agrolandscapes may complicate the strategy for managing Bt resistance in D. saccharalis, and designing a Bt resistance management strategy for D. saccharalis is challenging because of a lack of empirical data about overwintering and moth movement.

  16. 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...

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

    National Research Council Canada - National Science Library

    Gassmann, Aaron J; Petzold-Maxwell, Jennifer L; Keweshan, Ryan S; Dunbar, Mike W

    2011-01-01

    .... 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...

  18. screening of new isolates of bt and cloning of their dna amplicons

    African Journals Online (AJOL)

    NEMAPPA

    2012-09-18

    Sep 18, 2012 ... Nine new indigenous isolates of Bacillus thuringiensis (Bt) were characterized for their colony type, .... the presence of target DNA insert by colony PCR with ... H2O Control .... Aedes aegypti using next-generation sequencing.

  19. Bacterial communities of the cotton aphid Aphis gossypii associated with Bt cotton in northern China

    National Research Council Canada - National Science Library

    Zhao, Yao; Zhang, Shuai; Luo, Jun-Yu; Wang, Chun-Yi; Lv, Li-Min; Cui, Jin-Jie

    2016-01-01

    .... This study investigated the bacterial diversity of the cotton aphid Aphis gossypii associated with Bt cotton in northern China by targeting the V4 region of the 16S rDNA using the Illumina MiSeq platform...

  20. Plant defense against insect herbivores

    DEFF Research Database (Denmark)

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

    2013-01-01

    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...

  1. 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.

  2. 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.

  3. The end of a myth – Bt (Cry1Ab maize does not harm green lacewings

    Directory of Open Access Journals (Sweden)

    Joerg eRomeis

    2014-08-01

    Full Text Available A concern with Bt-transgenic insect-resistant plants is their potential to harm non-target organisms. Early studies reported that Cry1Ab-producing Bt maize and purified Cry1Ab harmed larvae of the green lacewing, Chrysoperla carnea. Although these effects could not be confirmed in subsequent studies, some authors still refer to them as evidence that Bt maize harms beneficial species. We provide a comprehensive review of the studies evaluating the effects of Bt (Cry1Ab maize on C. carnea. The evidence indicates that this important predator is not affected by Bt maize or by the produced Cry1Ab protein. We discuss how conceptual models can assist environmental risk assessments, and we emphasize the importance of robust and reproducible studies.

  4. The end of a myth-Bt (Cry1Ab) maize does not harm green lacewings.

    Science.gov (United States)

    Romeis, Jörg; Meissle, Michael; Naranjo, Steven E; Li, Yunhe; Bigler, Franz

    2014-01-01

    A concern with Bt-transgenic insect-resistant plants is their potential to harm non-target organisms. Early studies reported that Cry1Ab-producing Bt maize and purified Cry1Ab harmed larvae of the green lacewing, Chrysoperla carnea. Although these effects could not be confirmed in subsequent studies, some authors still refer to them as evidence that Bt maize harms beneficial species. We provide a comprehensive review of the studies evaluating the effects of Bt (Cry1Ab) maize on C. carnea. The evidence indicates that this important predator is not affected by Bt maize or by the produced Cry1Ab protein. We discuss how conceptual models can assist environmental risk assessments, and we emphasize the importance of robust and reproducible studies.

  5. The end of a myth—Bt (Cry1Ab) maize does not harm green lacewings

    Science.gov (United States)

    Romeis, Jörg; Meissle, Michael; Naranjo, Steven E.; Li, Yunhe; Bigler, Franz

    2014-01-01

    A concern with Bt-transgenic insect-resistant plants is their potential to harm non-target organisms. Early studies reported that Cry1Ab-producing Bt maize and purified Cry1Ab harmed larvae of the green lacewing, Chrysoperla carnea. Although these effects could not be confirmed in subsequent studies, some authors still refer to them as evidence that Bt maize harms beneficial species. We provide a comprehensive review of the studies evaluating the effects of Bt (Cry1Ab) maize on C. carnea. The evidence indicates that this important predator is not affected by Bt maize or by the produced Cry1Ab protein. We discuss how conceptual models can assist environmental risk assessments, and we emphasize the importance of robust and reproducible studies. PMID:25161661

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

    OpenAIRE

    Lawo, Nora C.; Felix L. Wäckers; Jörg Romeis

    2009-01-01

    Cotton varieties expressing Cry proteins derived from the soil bacterium Bacillus thuringiensis (Bt) are grown worldwide for the management of pest Lepidoptera. To prevent non-target pest outbreaks and to retain the biological control function provided by predators and parasitoids, the potential risk that Bt crops may pose to non-target arthropods is addressed prior to their commercialization. Aphids play an important role in agricultural systems since they serve as prey or host to a number o...

  7. Hybridizing transgenic Bt cotton with non-Bt cotton counters resistance in pink bollworm

    National Research Council Canada - National Science Library

    Wan, Peng; Xu, Dong; Cong, Shengbo; Jiang, Yuying; Huang, Yunxin; Wang, Jintao; Wu, Huaiheng; Wang, Ling; Wu, Kongming; Carriere, Yves; Mathias, Andrea; Li, Xianchun; Tabashnik, Bruce E

    2017-01-01

    .... However, these benefits are being eroded by evolution of resistance in pests. We report a strategy for combating resistance by crossing transgenic Bt plants with conventional non-Bt plants and then crossing the resulting first-generation (F1...

  8. Fitness of Bt-resistant cabbage loopers on Bt cotton plants.

    Science.gov (United States)

    Tetreau, Guillaume; Wang, Ran; Wang, Ping

    2017-10-01

    Development of resistance to the insecticidal toxins from Bacillus thuringiensis (Bt) in insects is the major threat to the continued success of transgenic Bt crops in agriculture. The fitness of Bt-resistant insects on Bt and non-Bt plants is a key parameter that determines the development of Bt resistance in insect populations. In this study, a comprehensive analysis of the fitness of Bt-resistant Trichoplusia ni strains on Bt cotton leaves was conducted. The Bt-resistant T. ni strains carried two genetically independent mechanisms of resistance to Bt toxins Cry1Ac and Cry2Ab. The effects of the two resistance mechanisms, individually and in combination, on the fitness of the T. ni strains on conventional non-Bt cotton and on transgenic Bt cotton leaves expressing a single-toxin Cry1Ac (Bollgard I) or two Bt toxins Cry1Ac and Cry2Ab (Bollgard II) were examined. The presence of Bt toxins in plants reduced the fitness of resistant insects, indicated by decreased net reproductive rate (R0 ) and intrinsic rate of increase (r). The reduction in fitness in resistant T. ni on Bollgard II leaves was greater than that on Bollgard I leaves. A 12.4-day asynchrony of adult emergence between the susceptible T. ni grown on non-Bt cotton leaves and the dual-toxin-resistant T. ni on Bollgard II leaves was observed. Therefore, multitoxin Bt plants not only reduce the probability for T. ni to develop resistance but also strongly reduce the fitness of resistant insects feeding on the plants. © 2017 The Authors. Plant Biotechnology Journal published by Society for Experimental Biology and The Association of Applied Biologists and John Wiley & Sons Ltd.

  9. Field-evolved insect resistance to Bt crops: definition, theory, and data.

    Science.gov (United States)

    Tabashnik, Bruce E; Van Rensburg, J B J; Carrière, Yves

    2009-12-01

    Transgenic crops producing Bacillus thuringiensis (Bt) toxins for insect pest control have been successful, but their efficacy is reduced when pests evolve resistance. Here we review the definition of field-evolved resistance, the relationship between resistance and field control problems, the theory underlying strategies for delaying resistance, and resistance monitoring methods. We also analyze resistance monitoring data from five continents reported in 41 studies that evaluate responses of field populations of 11 lepidopteran pests to four Bt toxins produced by Bt corn and cotton. After more than a decade since initial commercialization of Bt crops, most target pest populations remain susceptible, whereas field-evolved resistance has been documented in some populations of three noctuid moth species: Spodoptera frugiperda (J. E. Smith) to Cry1F in Bt corn in Puerto Rico, Busseola fusca (Fuller) to CrylAb in Bt corn in South Africa, and Helicoverpa zea (Boddie) to CrylAc and Cry2Ab in Bt cotton in the southeastern United States. Field outcomes are consistent with predictions from theory, suggesting that factors delaying resistance include recessive inheritance of resistance, abundant refuges of non-Bt host plants, and two-toxin Bt crops deployed separately from one-toxin Bt crops. The insights gained from systematic analyses of resistance monitoring data may help to enhance the durability of transgenic insecticidal crops. We recommend continued use of the longstanding definition of resistance cited here and encourage discussions about which regulatory actions, if any, should be triggered by specific data on the magnitude, distribution, and impact of field-evolved resistance.

  10. The end of a myth – Bt(Cry1Ab) maize does not harm green lacewings

    Science.gov (United States)

    A concern with Bt-transgenic insect-resistant plants is their potential to harm non-target organisms. Early studies reported that Cry1Ab-producing Bt maize and purified Cry1Ab harmed larvae of the green lacewing, Chrysoperla carnea. Although these effects could not be confirmed in subsequent studies...

  11. 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...

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

    Directory of Open Access Journals (Sweden)

    Nora C Lawo

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

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

    Science.gov (United States)

    Lawo, Nora C; Wäckers, Felix L; Romeis, Jörg

    2009-01-01

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

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

    DEFF Research Database (Denmark)

    1991-01-01

    -substratum binding assay in which the binding of BT4C and BT4Cn cells to NCAM immobilized to glass was assessed. We found that BT4C 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......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 producing experimental metastases, that of BT4Cn cells is high. In BT4C cells NCAM is synthesized as 4 polypeptides with Mr's of 190,000, 140,000, 115,000 and 97,000. The 140,000, 115,000 and 97,000 polypeptides are glycosylated and for the 140,000 and 115,000 polypeptides sulfatation is observed...

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

    DEFF Research Database (Denmark)

    Yuan, Yiyang; Krogh, Paul Henning; Bai, Xue

    2014-01-01

    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.......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...

  16. Use of Industrial Components in SL/BT Equipment Controls

    CERN Document Server

    Carlier, E

    1999-01-01

    The control system of all SPS target stations, beam absorbers and other aperture limiting devices is presently being refurbished, using solely standard industrial hardware and software components. SIEMENS Simatic S7-300 programmable logic controllers serve as equipment controllers. They are connected through Profibus to a WinNT front-end running the SIEMENS WinCC SCADA package which acts as local controller and gateway for remote access. A variant configuration, where the PLCs are directly linked to Ethernet, has been used for controlling the SPS Q measurement kickers. These and some other SL/BT projects will be reviewed where fully off-the-shelf components have been successfully integrated into the SL accelerator controls infrastructure. The arguments leading to the various technical choices will be laid down including a report of the experience gained. Finally, the presentation will address the perspective and current ideas for using industrial components in controlling SL/BT equipment during the LHC era.

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

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yongbo, E-mail: liuyb@craes.org.cn [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Liu, Fang [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Wang, Chao [Pearl River Fisheries Research Institute, Chinese Academy of Fishery Science, Guangzhou 510380 (China); Quan, Zhanjun [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China); Li, Junsheng, E-mail: lijsh@creas.org.cn [State Key Laboratory of Environmental Criteria and Risk Assessment, Chinese Research Academy of Environmental Sciences, Beijing 100012 (China)

    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. - Highlights: • We detect fusion Cry1Ab/1Ac proteins from Bt rice entering into aquatic ecosystems. • Bt-transgenic rice cultivation have no significant effect on zooplankton community. • Bt-transgenic rice cultivation have indirect effect on phytoplankton community. • Water quality explains the difference of plankton communities in adjacent ditches.

  18. Pest management through Bacillus thuringiensis (Bt) in a tea-silkworm ecosystem: status and potential prospects.

    Science.gov (United States)

    Dashora, Kavya; Roy, Somnath; Nagpal, Akanksha; Roy, Sudipta Mukhopadhyay; Flood, Julie; Prasad, Anjali Km; Khetarpal, Ravinder; Neave, Suzanne; Muraleedharan, N

    2017-03-01

    Bacillus thuringiensis (Bt) is a soil bacterium that forms spores containing crystals comprising one or more Cry or Cyt proteins having potential and specific insecticidal activity. Different strains of Bt produce different types of toxins, affecting a narrow taxonomic group of insects. Therefore, it is used in non-chemical pest management, including inherent pest resistance through GM crops. The specificity of action of Bt toxins reduces the concern of adverse effects on non-target species, a concern which remains with chemical insecticides as well. To make use of Bt more sustainable, new strains expressing novel toxins are actively being sought globally. Since Bt is successfully used against many pests including the lepidopteran pests in different crop groups, the insecticidal activity against Samia cynthia (Drury) (Eri silkworm) and Antheraea assamensis Helfer (Muga silkworm) becomes a concern in the state of Assam in India which is a predominantly tea- and silk-producing zone. Though Bt can be used as an effective non-chemical approach for pest management for tea pests in the same geographical region, yet, it may potentially affect the silk industry which depends on silkworm. There is a need to identify the potentially lethal impact (through evaluating their mortality potential) of local Bt strains on key silkworm species in North Eastern India. This will allow the use of existing Bt for which the silkworms have natural resistance. Through this review, the authors aim to highlight recent progress in the use of Bt and its insecticidal toxins in tea pest control and the potential sensitivity for tea- and silk-producing zone of Assam in India.

  19. 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

  20. 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.

  1. Plant Defense against Insect Herbivores

    Science.gov (United States)

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

    2013-01-01

    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. PMID:23681010

  2. Effects of transgenic Bt+CpTI cotton on the growth and reproduction of earthworm Eisenia foetida.

    Science.gov (United States)

    Liu, Biao; Cui, Jinjie; Meng, Jun; Hu, Wenjun; Luo, Junyu; Zheng, Yangping

    2009-01-01

    With the expansion of the planted area of transgenic Bt+CpTI cotton, the effects of this crop on non-target organisms in soil, including earthworms, are becoming the most important aspect of their ecological risk assessment. Laboratory toxicity studies were conducted to determine the effects of transgenic Bt+CpTI cotton leaves, containing high concentrations of the Bt toxin and cowpea trypsin inhibitor, on the earthworm Eisenia foetida. In comparison with the non-transgenic cotton line Zhong23, transgenic Bt+CpTI cotton Zhong41 had no significant acute toxicity on E. foetida. Moreover, the leaves of transgenic Bt+CpTI cotton were more suitable than the non-transgenic cotton Zhong23 for E. foetida growth and reproduction (time of reproduction, the number of cocoons and newly incubated offspring).

  3. Herbicide and insect resistant Bt cotton pollen assessment finds no detrimental effects on adult honey bees.

    Science.gov (United States)

    Niu, Lin; Ma, Weihua; Lei, Chaoliang; Jurat-Fuentes, Juan Luis; Chen, Lizhen

    2017-11-01

    One important concern regarding the use of transgenic cotton expressing insecticidal toxins from the bacterium Bacillus thuringiensis (Bt) is its potential detrimental effect on non-target organisms. The honey bee (Apis mellifera) is the most important pollinator species worldwide and it is directly exposed to transgenic crops by the consumption of genetically modified (GM) pollen. However, the potential effects of Bt cotton on A. mellifera remain unclear. In the present study, we assessed the effects of two Bt cotton varieties; ZMSJ expressing the Cry1Ac and Cry2Ab insecticidal proteins, and ZMKCKC producing Cry1Ac and EPSPS, on A. mellifera. Feeding on pollen from two Bt cotton varieties led to detection of low levels of Cry toxins (<10 ng/g fresh weight) in the midgut of A. mellifera adults, yet expression of detoxification genes did not change significantly compared to feeding on non-Bt cotton. Binding assays showed no Cry1Ac or Cry2Ab binding to midgut brush border membrane proteins from A. mellifera adults. Taken together, these results support minimal risk for potential negative effects on A. mellifera by exposure to Bt cotton. Copyright © 2017 Elsevier Ltd. All rights reserved.

  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. Transgenic Bt Cotton Does Not Disrupt the Top-Down Forces Regulating the Cotton Aphid in Central China.

    Science.gov (United States)

    Yao, Yong-Sheng; Han, Peng; Niu, Chang-Ying; Dong, Yong-Cheng; Gao, Xi-Wu; Cui, Jin-Jie; Desneux, Nicolas

    2016-01-01

    Top-down force is referred to arthropod pest management delivered by the organisms from higher trophic levels. In the context of prevalent adoption of transgenic Bt crops that produce insecticidal Cry proteins derived from Bacillus thuringiensis (Bt), it still remains elusive whether the top-down forces are affected by the insect-resistant traits that introduced into the Bt crops. We explored how Bt cotton affect the strength of top-down forces via arthropod natural enemies in regulating a non-target pest species, the cotton aphid Aphis gossypii Glover, using a comparative approach (i.e. Bt cotton vs. conventional cotton) under field conditions. To determine top-down forces, we manipulated predation/parasitism exposure of the aphid to their natural enemies using exclusion cages. We found that the aphid population growth was strongly suppressed by the dominant natural enemies including Coccinellids, spiders and Aphidiines parasitoids. Coccinellids, spiders and the assemblage of other arthropod natural enemies (mainly lacewings and Hemipteran bugs) are similarly abundant in both plots, but with the parasitoid mummies less abundant in Bt cotton plots compared to the conventional cotton plots. However, the lower abundance of parasitoids in Bt cotton plots alone did not translate into differential top-down control on A. gossypii populations compared to conventional ones. Overall, the top-down forces were equally strong in both plots. We conclude that transgenic Bt cotton does not disrupt the top-down forces regulating the cotton aphid in central China.

  6. Transgenic Bt Cotton Does Not Disrupt the Top-Down Forces Regulating the Cotton Aphid in Central China.

    Directory of Open Access Journals (Sweden)

    Yong-Sheng Yao

    Full Text Available Top-down force is referred to arthropod pest management delivered by the organisms from higher trophic levels. In the context of prevalent adoption of transgenic Bt crops that produce insecticidal Cry proteins derived from Bacillus thuringiensis (Bt, it still remains elusive whether the top-down forces are affected by the insect-resistant traits that introduced into the Bt crops. We explored how Bt cotton affect the strength of top-down forces via arthropod natural enemies in regulating a non-target pest species, the cotton aphid Aphis gossypii Glover, using a comparative approach (i.e. Bt cotton vs. conventional cotton under field conditions. To determine top-down forces, we manipulated predation/parasitism exposure of the aphid to their natural enemies using exclusion cages. We found that the aphid population growth was strongly suppressed by the dominant natural enemies including Coccinellids, spiders and Aphidiines parasitoids. Coccinellids, spiders and the assemblage of other arthropod natural enemies (mainly lacewings and Hemipteran bugs are similarly abundant in both plots, but with the parasitoid mummies less abundant in Bt cotton plots compared to the conventional cotton plots. However, the lower abundance of parasitoids in Bt cotton plots alone did not translate into differential top-down control on A. gossypii populations compared to conventional ones. Overall, the top-down forces were equally strong in both plots. We conclude that transgenic Bt cotton does not disrupt the top-down forces regulating the cotton aphid in central China.

  7. Quantification of Bt δ-endotoxins in leaf tissues of tropical Bt maize ...

    African Journals Online (AJOL)

    Murenga Mwimali

    2012-06-26

    Jun 26, 2012 ... In Kenya, stem borers destroy an estimated 13.5% of farmers' annual maize harvest. Maize transformed using Bacillus thuringiensis (Bt) derived genes controls stem borers without negative effects to humans, livestock or the environment. The effectiveness and sustainability of Bt transgenic technology.

  8. Quantification of Bt δ-endotoxins in leaf tissues of tropical Bt maize ...

    African Journals Online (AJOL)

    Maize transformed using Bacillus thuringiensis (Bt) derived genes controls stem borers without negative effects to humans, livestock or the environment. ... The objective of this study was to assess under greenhouse conditions the concentration levels of Bt δ-endotoxins in the leaf tissues of the parents, the F1, and the F2:3 ...

  9. 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. © 2015 Ivashuta et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society.

  10. Cannibalism of Helicoverpa zea (Lepidoptera: Noctuidae) from Bacillus thuringiensis (Bt) transgenic corn versus non-Bt corn.

    Science.gov (United States)

    Chilcutt, Charles F

    2006-06-01

    Because of the importance of cannibalism in population regulation of Helicoverpa zea (Boddie) (Lepidoptera: Noctuidae) in corn, Zea mays L., it is useful to understand the interactions between Bacillus thuringiensis (Bt) transgenic corn and cannibalism. To determine the effects of Bt corn on cannibalism in H. zea, pairs of the same or different instars were taken from Bt or non-Bt corn and placed on artificial diet in proximity. Cannibalism occurred in 91% of pairs and was approximately 7% greater for pairs of larvae reared from Bt transgenic corn (95%) than from non-Bt corn (88%). Also, first instar by first instar pairs had a lower rate of cannibalism than other pairs. Time until cannibalism was not different for larvae from Bt corn versus non-Bt corn. Pupation rate of cannibals and surviving victims was not different for pairs from Bt corn versus non-Bt corn. Finally, cannibalism increased pupation rate of cannibals from both Bt and non-Bt corn by approximately 23 and 12%, respectively, although the increases were not significant. Thus, negative effects of Bt on larvae were compensated by increased cannibalism in comparison with larvae reared on non-Bt corn, which increased larval survival to levels comparable with larvae reared on non-Bt plants.

  11. 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.

  12. Increased mortality is predicted of Inachis io larvae caused by Bt-maize pollen in European farmland

    DEFF Research Database (Denmark)

    Holst, Niels; Lang, Andreas; Lövei, Gabor L

    2013-01-01

    A potential environmental risk of the field cultivation of insect-resistant (Bt-toxin expressing) transgenic maize (Zea mays) is the consumption of Bt-containing pollen by herbivorous larvae of butterflies (Lepidoptera). Maize is wind-pollinated, and at flowering time large amounts of pollen can...... be deposited on various plants growing in the landscape, leading to inadvertent ingestion of toxic pollen with plant biomass consumed by these butterfly larvae. To examine the possible effect of this coincidence, we focused our study on the protected butterfly Inachis io and two regions of Europe. Using...... climatic records, maize and butterfly phenology data, we built a simulation model of the butterfly's annual life cycle, overlaid with the phenology of maize pollen deposition on the leaves of the food plant Urtica dioica, and linked these with the dose–response curve of I. io larvae to Bt-maize pollen...

  13. 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

  14. [Bt gene flow of transgeic cotton].

    Science.gov (United States)

    Shen, F F; Yu, Y J; Zhang, X K; Bi, J J; Yin, C Y

    2001-01-01

    This study was carried out to determine the gene flow of transgenic cotton under Chinese ecological environment. Transgenic cotton GK-12 containing the marker gene NPTII and Bt gene was planted in the 6 x 6 m2 plot, non-transgenic cotton CCRC 12 and Xinmian 13 were planted respectively around them. At varying distances from transgenic cotton, seeds produced by the non-transgenic cotton were collected and screened for marker gene and Bt gene using kanamycine sulphate and Dot-ELISA method. PCR technique was also used in some seeds to screen Bt gene. The result indicated that gene flow was found to be high at 0-6 m, and to decrease with distances; however gene flow occurred up to distance of 36 m from the transgenic cotton plot. Bt gene flow at 3-6 m increased with increasing the diversity of transgenic cotton in the plot, but gene flow increased little at long distance. The gene flow between species was lower than between cultivars at 0-6 m, and occurred at the distance of 72 m from transgenic plot. 72 m buffer zones would serve to limit gene flow of transgenic cotton from small-scale field test. The possibility of escapes of engineered gene to wild relatives of cotton species was also discussed.

  15. Can alien plants support generalist insect herbivores?

    Science.gov (United States)

    Douglas Tallamy; Meg Ballard; Vincent. D' Amico

    2009-01-01

    Rearing experiments were conducted to address two questions relevant to understanding how generalist lepidopteran herbivores interact with alien plants. We reared 10 yellow-striped armyworms (Spodoptera ornithogalli),...

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

    NARCIS (Netherlands)

    Amo, L.; Jansen, J.J.; Van Dam, 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

  17. 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.

  18. Reproduction of root knot nematode (Meloidogyne incognita) on Bt ...

    African Journals Online (AJOL)

    SARAH

    2013-09-30

    Sep 30, 2013 ... ELISA detected Bt protein in soil and roots of Bt cotton but not in HART 89M and isoline plant tissues and soil. Reaction of Bt cotton and isoline to M. incognita was different with the transgenic cotton being more susceptible to RKN. HART 89M was more resistant to RKN infection ... borne fungal pathogens.

  19. Dicty_cDB: FC-BT05 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available library) FC-BT05 (Link to dictyBase) - - - Contig-U15224-1 FC-BT05Z (Link to Original site) - - FC-BT05Z 559...559 - - - - Show FC-BT05 Library FC (Link to library) Clone ID FC-BT05 (Link to dictyBase) Atlas ID - NBRP...biol.tsukuba.ac.jp/CSM/FC/FC-BT/FC-BT05Q.Seq.d/ Representative seq. ID FC-BT05Z (Link to Original site)...Representative DNA sequence >FC-BT05 (FC-BT05Q) /CSM/FC/FC-BT/FC-BT05Q.Seq.d/ XXXXXXXXXXCCGTTGGTAATA...significant alignments: (bits) Value FC-BT05 (FC-BT05Q) /CSM/FC/FC-BT/FC-BT05Q.Seq.d/ 569 e-161 FC-BS01 (FC-BS01Q)

  20. Dicty_cDB: FC-BT03 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available (Link to library) FC-BT03 (Link to dictyBase) - G24094 DDB0218223 Contig-U15225-1 FC-BT03E (Link to Original...site) - - - - - - FC-BT03E 625 Show FC-BT03 Library FC (Link to library) Clone ID FC-BT03 (Link to dictyBase)...biol.tsukuba.ac.jp/CSM/FC/FC-BT/FC-BT03Q.Seq.d/ Representative seq. ID FC-BT03E (Link to Original site)...Representative DNA sequence >FC-BT03 (FC-BT03Q) /CSM/FC/FC-BT/FC-BT03Q.Seq.d/ AGGAAATGAACAAGCAAAAAAA...significant alignments: (bits) Value FC-BT03 (FC-BT03Q) /CSM/FC/FC-BT/FC-BT03Q.Seq.d/ 351 8e-96 SSM865 (SSM865Q)

  1. Dicty_cDB: FC-BT01 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available FC (Link to library) FC-BT01 (Link to dictyBase) - - - Contig-U16455-1 FC-BT01E (Link to Original site)...site) - - - - - - FC-BT01E 595 Show FC-BT01 Library FC (Link to library) Clone ID FC-BT01 (Link to dictyBase)...biol.tsukuba.ac.jp/CSM/FC/FC-BT/FC-BT01Q.Seq.d/ Representative seq. ID FC-BT01E (Link to Original site)...Representative DNA sequence >FC-BT01 (FC-BT01Q) /CSM/FC/FC-BT/FC-BT01Q.Seq.d/ TGCATCACGAACAACTCCCAGA...significant alignments: (bits) Value FC-BT01 (FC-BT01Q) /CSM/FC/FC-BT/FC-BT01Q.Seq.d/ 1041 0.0 SLC814 (SLC814Q)

  2. Dicty_cDB: FC-BT06 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available library) FC-BT06 (Link to dictyBase) - - - Contig-U15479-1 FC-BT06Z (Link to Original site) - - FC-BT06Z 648...648 - - - - Show FC-BT06 Library FC (Link to library) Clone ID FC-BT06 (Link to dictyBase) Atlas ID - NBRP...biol.tsukuba.ac.jp/CSM/FC/FC-BT/FC-BT06Q.Seq.d/ Representative seq. ID FC-BT06Z (Link to Original site)...Representative DNA sequence >FC-BT06 (FC-BT06Q) /CSM/FC/FC-BT/FC-BT06Q.Seq.d/ XXXXXXXXXXACGTGTTGGTGC...significant alignments: (bits) Value FC-BT06 (FC-BT06Q) /CSM/FC/FC-BT/FC-BT06Q.Seq.d/ 942 0.0 VFL888 (VFL888Q)

  3. 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.

  4. 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

  5. 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

  6. Novel Pink Bollworm Resistance to the Bt Toxin Cry 1Ac: Effects on Mating, Oviposition, Larval Development and Survival

    Science.gov (United States)

    Fabrick, J.A.; Forlow Jech, L.; Henneberry, T. J.

    2009-01-01

    Bt cotton plants are genetically engineered to produce insecticidal toxins from the Bacillus thuringiensis (Bt) Berliner (Bacillales: Bacillaceae) bacterium and target key lepidopteran pests. In all previous strains of pink bollworm, Pectinophora gossypiella (Saunders) (Lepidoptera: Gelechiidae) selected in the laboratory for resistance to insecticidal Cry1Ac toxin using an artificial diet containing the toxin, resistance to Cry1Ac and to Bt cotton is linked to three cadherin alleles (r1, r2, and r3). In contrast, the BG(4) pink bollworm strain was selected for resistance to Bt cotton by feeding larvae for four days in each of 42 generations on bolls of ‘NuCOTN33B®’ that expressed Cry1Ac toxin. After additional selection for eleven generations on Cry1Ac-incorporated diet, the susceptibility to Cry1Ac, fecundity, egg viability, and mating of this strain (Bt4R) was compared with the unselected Cry1Ac-susceptible parent strain. Some larvae of the Bt4R strain survived on diet containing ≥ 10 µg Cry1Ac per milliliter artificial diet, but none survived on transgenic cotton bolls. In contrast to strains selected exclusively on Cry1Ac diet, some survival of progeny of reciprocal moth crosses of Bt4R resistant and Bt-susceptible strains occurred on Cry1Ac-treated diet, suggesting differences in levels of dominance. The Bt4R resistant strain does not have the r1, r2, or r3 mutant cadherin genes as do all previous strains of pink bollworm selected on Cry1Ac-treated artificial diet. The combined results suggest a mechanism of resistance to Cry1Ac that is different from previously described cadherin mutations. PMID:19613847

  7. 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

  8. Research Note Do mammalian herbivores influence invertebrate ...

    African Journals Online (AJOL)

    We investigated the indirect influence of mammalian herbivores on invertebrates, by utilising long-term mammalian herbivore exclosures in Kruger National Park. The exclosures span three distinct habitat types (crest, footslope and riparian) on a catena. By performing invertebrate collections in the exclosures and in a ...

  9. Effects of herbivores on grassland plant diversity.

    NARCIS (Netherlands)

    Olff, H.; Ritchie, M.E.

    1998-01-01

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

  10. Plant defences against herbivore and insect attack

    Science.gov (United States)

    Plants deploy a number of defences against attack by insects and other herbivores. Direct defence is conferred by plant products and structures that deter or kill the herbivores. Chemical toxins and deterrents vary widely among plant species, and some typical toxins include alkaloids, terpenoids, st...

  11. Stoichiometric food quality and herbivore dynamics.

    NARCIS (Netherlands)

    Muller, E.B.; Nisbet, R.M.; Kooijman, S.A.L.M.; Elser, J.J.; McCauley, E.

    2001-01-01

    Herbivores may grow with nutrient or energy limitation, depending on food abundance and the chemical composition of their food. We present a model that describes herbivore growth as a continuous function of two limiting factors. This function uses the synthesizing unit concept, has the hyperbolic

  12. Effects of Bt cotton on Thrips tabaci (Thysanoptera: Thripidae) and its predator, Orius insidiosus (Hemiptera: Anthocoridae).

    Science.gov (United States)

    Kumar, Rishi; Tian, Jun-Ce; Naranjo, Steven E; Shelton, Anthony M

    2014-06-01

    Laboratory studies were conducted to investigate tritrophic transfer of insecticidal Cry proteins from transgenic cotton to an herbivore and its predator, and to examine effects of these proteins on the predator's development, survival, and reproduction. Cry1Ac and Cry2Ab proteins from the bacterium Bacillus thuringiensis (Bt) produced in Bollgard-II (BG-II, Event 15985) cotton plants were acquired by Thrips tabaci Lindeman (Thysanoptera: Thripidae), an important sucking pest of cotton, and its generalist predator, Orius insidiosus (Say) (Hemiptera: Anthocoridae). The average protein titers in BG-II cotton leaves were 1,256 and 43,637 ng Cry1Ac and Cry2Ab per gram fresh leaf tissue, respectively. At the second trophic level, larvae of T. tabaci reared on BG-II cotton for 48-96 h had 22.1 and 2.1% of the Cry1Ac and Cry2Ab levels expressed in leaves, respectively. At the third trophic level, O. insidiosus that fed on T. tabaci larvae had 4.4 and 0.3% of the Cry1Ac and Cry2Ab protein levels, respectively, expressed in BG-II plants. O. insidiosus survivorship, time of nymphal development, adult weight, preoviposition and postoviposition periods, fecundity, and adult longevity were not adversely affected owing to consumption of T. tabaci larvae that had fed on BG-II cotton compared with non-Bt cotton. Our results indicate that O. insidiosus, a common predator of T. tabaci, is not harmed by BG-II cotton when exposed to Bt proteins through its prey. Thus, O. insidiosus can continue to provide important biological control services in the cotton ecosystem when BG-II cotton is used to control primary lepidopteran pests.

  13. Sixteen Years of Bt Maize in the EU Hotspot: Why Has Resistance Not Evolved?

    Directory of Open Access Journals (Sweden)

    Pedro Castañera

    Full Text Available The majority of Bt maize production in the European Union (EU is concentrated in northeast Spain, which is Europe's only hotspot where resistance might evolve, and the main target pest, Sesamia nonagrioides, has been exposed to Cry1Ab maize continuously since 1998. The cropping system in northeast Spain has some similar characteristics to those that probably led to rapid resistance failures in two other target noctuid maize pests. These include repeated cultivation of Bt maize in the same fields, low use of refuges, recurring exposure of larvae to non-high dose concentrations of Cry1Ab toxin during the first years of cultivation, low migratory potential, and production concentrated in an irrigated region with few alternative hosts. Available data reveal no evidence of resistance in S. nonagrioides after 16 years of use. We explore the possible reasons for this resistance management success using evolutionary models to consider factors expected to accelerate resistance, and those expected to delay resistance. Low initial adoption rates and the EU policy decision to replace Event 176 with MON 810 Bt maize were key to delaying resistance evolution. Model results suggest that if refuge compliance continues at the present 90%, Bt maize might be used sustainably in northeast Spain for at least 20 more years before resistance might occur. However, obtaining good estimates of the present R allele frequency and level of local assortative mating are crucial to reduce uncertainty about the future success of resistance management.

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

    Directory of Open Access Journals (Sweden)

    Desiree M Hautea

    Full Text Available 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.

  15. 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.

  16. Ecosystem implications of conserving endemic versus eradicating introduced large herbivores in the Galapagos Archipelago

    Science.gov (United States)

    Bastille-Rousseau, Guillaume; Gibbs, James P.; Campbell, Karl; Yackulic, Charles B.; Blake, Stephen

    2017-01-01

    Restoration of damaged ecosystems through invasive species removal and native species conservation is an increasingly common practice in biodiversity conservation. Estimating the degree of ecosystem response attributable specifically to eradication of exotic herbivores versus restoration of native herbivores is often difficult and is complicated by concurrent temporal changes in other factors, especially climate. We investigated the interactive impacts of native mega-herbivores (giant tortoises) and the eradication of large alien herbivores (goats) on vegetation productivity across the Galapagos Archipelago. We examined archipelago-wide patterns of Normalized Difference Vegetation Index (NDVI) as a proxy for vegetation productivity between 2001 and 2015 and evaluated how goat and historical and current tortoise occurrence influenced productivity. We used a breakpoint analysis to detect change in trends in productivity from five targeted areas following goat eradication. We found a positive association between tortoise occurrence and vegetation productivity and a negative association with goat occurrence. We also documented an increase in plant productivity following goat removal with recovery higher in moister regions than in arid region, potentially indicating an alternate stable state has been created in the latter. Climate variation also contributed to the detected improvement in productivity following goat eradication, sometimes obscuring the effect of eradication but more usually magnifying it by up to 300%. Our work offers perspectives regarding the effectiveness and outcomes of eradicating introduced herbivores and re-introducing native herbivores, and the merits of staging them simultaneously in order to restore critical ecosystem processes such as vegetation productivity.

  17. Mathematical models for plant-herbivore interactions

    Science.gov (United States)

    Feng, Zhilan; DeAngelis, Donald L.

    2017-01-01

    Mathematical Models of Plant-Herbivore Interactions addresses mathematical models in the study of practical questions in ecology, particularly factors that affect herbivory, including plant defense, herbivore natural enemies, and adaptive herbivory, as well as the effects of these on plant community dynamics. The result of extensive research on the use of mathematical modeling to investigate the effects of plant defenses on plant-herbivore dynamics, this book describes a toxin-determined functional response model (TDFRM) that helps explains field observations of these interactions. This book is intended for graduate students and researchers interested in mathematical biology and ecology.

  18. Foraging behaviour of parasitoids in multi-herbivore communities

    NARCIS (Netherlands)

    Rijk, de M.

    2016-01-01

    Foraging behaviour of parasitoids in multi-herbivore communities Parasitic wasps, or parasitoids, use herbivore-induced plant volatiles and infochemicals produced directly by the herbivore to locate their herbivorous hosts. This process could be interrupted by the presence of

  19. Keystone Herbivores and the Evolution of Plant Defenses

    NARCIS (Netherlands)

    Poelman, Erik H.; Kessler, André

    2016-01-01

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

  20. Variation in composition of predator-attracting allelochemicals emitted by herbivore-infested plants: relative influence of plant and herbivore.

    NARCIS (Netherlands)

    Takabayashi, J.; Dicke, M.; Posthumus, M.A.

    1991-01-01

    During foraging, natural enemies of herbivores may employ volatile allelochemicals that originate from an interaction of the herbivore and its host plant. The composition of allelochemical blends emitted by herbivore-infested plants is known to be affected by both the herbivore and the plant. Our

  1. TOEFL strategies a complete guide to the iBT

    CERN Document Server

    Stirling, Bruce

    2016-01-01

    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 TOEFL STRATEGIES A COMPLETE GUIDE gives you, and more!

  2. Learning in Insect Pollinators and Herbivores.

    Science.gov (United States)

    Jones, Patricia L; Agrawal, Anurag A

    2017-01-31

    The relationship between plants and insects is influenced by insects' behavioral decisions during foraging and oviposition. In mutualistic pollinators and antagonistic herbivores, past experience (learning) affects such decisions, which ultimately can impact plant fitness. The higher levels of dietary generalism in pollinators than in herbivores may be an explanation for the differences in learning seen between these two groups. Generalist pollinators experience a high level of environmental variation, which we suggest favors associative learning. Larval herbivores employ habituation and sensitization-strategies useful in their less variable environments. Exceptions to these patterns based on habitats, mobility, and life history provide critical tests of current theory. Relevant plant traits should be under selection to be easily learned and remembered in pollinators and difficult to learn in herbivores. Insect learning thereby has the potential to have an important, yet largely unexplored, role in plant-insect coevolution.

  3. Effects of BT-11 on memory in healthy humans.

    Science.gov (United States)

    Lee, Jun-Young; Kim, Ka Young; Shin, Ki Young; Won, Beom Young; Jung, Hee Yeon; Suh, Yoo-Hun

    2009-04-24

    We previously reported that BT-11, the extract of dried roots of Polygala tenuifolia Willdenow, had neuroprotective effects and improved scopolamine- and stress-induced amnesia in rats. It also blocked the activity of acetylcholinesterase and enhanced glucose utilization in the rat brain. Therefore, we examined whether BT-11 could enhance memory in healthy humans. This study was a randomized, double-blind, placebo-controlled, parallel-group study of BT-11 in healthy adults. The participants were given capsules of BT-11 or placebo 3 times daily for 4 weeks. The Korean version of the California Verbal Learning Test (K-CVLT) and the Self-Ordered Pointing Test (SOPT) were used to assess verbal memory and working memory, respectively. The subjects in BT-11-treated group showed more significant increases in immediate recall on the K-CVLT than those in the placebo-treated group. In a comparison within each group, the subjects' scores on most subtests of the K-CVLT were significantly increased by both placebo and BT-11 treatment. Interestingly, the subjects' scores on the recognition subtest of the K-CVLT were significantly increased by BT-11 treatment but not by placebo treatment. Also, BT-11 treatment significantly reduced the number of errors on the SOPT, whereas placebo treatment did not. We are the first to show that BT-11 has memory-enhancing effects and may be a memory-enhancing drug in healthy adults.

  4. Interactions between Bt crops and aquatic ecosystems: A review.

    Science.gov (United States)

    Venter, Hermoine J; Bøhn, Thomas

    2016-12-01

    The term Bt crops collectively refers to crops that have been genetically modified to include a gene (or genes) sourced from Bacillus thuringiensis (Bt) bacteria. These genes confer the ability to produce proteins toxic to certain insect pests. The interaction between Bt crops and adjacent aquatic ecosystems has received limited attention in research and risk assessment, despite the fact that some Bt crops have been in commercial use for 20 yr. Reports of effects on aquatic organisms such as Daphnia magna, Elliptio complanata, and Chironomus dilutus suggest that some aquatic species may be negatively affected, whereas other reports suggest that the decreased use of insecticides precipitated by Bt crops may benefit aquatic communities. The present study reviews the literature regarding entry routes and exposure pathways by which aquatic organisms may be exposed to Bt crop material, as well as feeding trials and field surveys that have investigated the effects of Bt-expressing plant material on such organisms. The present review also discusses how Bt crop development has moved past single-gene events, toward multigene stacked varieties that often contain herbicide resistance genes in addition to multiple Bt genes, and how their use (in conjunction with co-technology such as glyphosate/Roundup) may impact and interact with aquatic ecosystems. Lastly, suggestions for further research in this field are provided. Environ Toxicol Chem 2016;35:2891-2902. © 2016 SETAC. © 2016 SETAC.

  5. 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.

  6. Impacts of Insect Herbivores on Plant Populations.

    Science.gov (United States)

    Myers, Judith H; Sarfraz, Rana M

    2017-01-31

    Apparent feeding damage by insects on plants is often slight. Thus, the influences of insect herbivores on plant populations are likely minor. The role of insects on host-plant populations can be elucidated via several methods: stage-structured life tables of plant populations manipulated by herbivore exclusion and seed-addition experiments, tests of the enemy release hypothesis, studies of the effects of accidentally and intentionally introduced insect herbivores, and observations of the impacts of insect species that show outbreak population dynamics. These approaches demonstrate that some, but not all, insect herbivores influence plant population densities. At times, insect-feeding damage kills plants, but more often, it reduces plant size, growth, and seed production. Plant populations for which seed germination is site limited will not respond at the population level to reduced seed production. Insect herbivores can influence rare plant species and need to be considered in conservation programs. Alterations due to climate change in the distributions of insect herbivores indicate the possibility of new influences on host plants. Long-term studies are required to show if density-related insect behavior stabilizes plant populations or if environmental variation drives most temporal fluctuations in plant densities. Finally, insects can influence plant populations and communities through changing the diversity of nonhost species, modifying nutrient fluxes, and rejuvenating over mature forests.

  7. 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.

  8. 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.

  9. Coping with Ex-ante Regulations for Planting Bt Maize: The Portuguese Experience

    NARCIS (Netherlands)

    Skevas, T.; Wesseler, J.H.H.; Fevereiro, P.

    2009-01-01

    This article investigates the attitude and practices of Bt and non-Bt maize farmers in Portugal. Thirty-seven Bt maize farmers were interviewed, representing 22.5% of the total number of Bt maize notifications in the country and 31.5% of the total area planted with Bt maize in 2007. Additionally, 66

  10. Mapping of common bunt resistance gene Bt9 in wheat.

    Science.gov (United States)

    Steffan, Philipp Matthias; Torp, Anna Maria; Borgen, Anders; Backes, Gunter; Rasmussen, Søren K

    2017-05-01

    The Bt9 resistance locus was mapped and shown to be distinct from the Bt10 locus. New markers linked to Bt9 have been identified and may be used to breed for resistance towards the seed-borne disease. Increasing organic wheat production in Denmark, and in other wheat-producing areas, in conjunction with legal requirements for organic seed production, may potentially lead to a rise in common bunt occurrence. As systemic pesticides are not used in organic farming, organic wheat production systems may benefit from genetic resistances. However, little is known about the underlying genetic mechanisms and locations of the resistance factors for common bunt resistance in wheat. A double haploid (DH) population segregating for common bunt resistance was used to identify the chromosomal location of common bunt resistance gene Bt9. DH lines were phenotyped in three environments and genotyped with DArTseq and SSR markers. The total length of the resulting linkage map was 2882 cM distributed across all 21 wheat chromosomes. Bt9 was mapped to the distal end of chromosome 6DL. Since wheat common bunt resistance gene Bt10 is also located on chromosome 6D, the possibility of their co-location was investigated. A comparison of marker sequences linked to Bt9 and Bt10 on physical maps of chromosome 6D confirmed that Bt9 and Bt10 are two distinct resistance factors located at the distal (6DL) and proximal (6DS) end, respectively, of chromosome 6D. Five new SSR markers Xgpw4005-1, Xgpw7433, Xwmc773, Xgpw7303 and Xgpw362 and many SNP and PAV markers flanking the Bt9 resistance locus were identified and they may be used in the future for marker-assisted selection.

  11. Root herbivore identity matters in plant-mediated interactions between root and shoot herbivores

    NARCIS (Netherlands)

    Wurst, S.; Putten, van der W.H.

    2007-01-01

    Plants are simultaneously attacked by a multitude of herbivores that affect plant responses and plant-mediated interactions in a variety of ways. So far, studies on indirect interactions between below- and aboveground herbivores have almost exclusively focused on interactions between only one root

  12. Bacterial communities of the cotton aphid Aphis gossypii associated with Bt cotton in northern China

    OpenAIRE

    Yao Zhao; Shuai Zhang; Jun-Yu Luo; Chun-Yi Wang; Li-Min Lv; Jin-Jie Cui

    2016-01-01

    Aphids are infected with a wide variety of endosymbionts that can confer ecologically relevant traits. However, the bacterial communities of most aphid species are still poorly characterized. This study investigated the bacterial diversity of the cotton aphid Aphis gossypii associated with Bt cotton in northern China by targeting the V4 region of the 16S rDNA using the Illumina MiSeq platform. Our sequencing data revealed that bacterial communities of A. gossypii were generally dominated by t...

  13. Comparison of Bt formulations against the spruce budworm

    Science.gov (United States)

    Lew McCreery; Imants Millers; Dennis Souto; Bruce Francis

    1985-01-01

    The Passamaquoddy Indian Forestry Department treated 40,300 acres in Maine in 1983 using Bt to protect red spruce and eastern hemlock from spruce budworm damage. The post treatment evaluation indicated that the protection objectives were achieved. In cooperation between the Passamaquoddy Indian Forestry Department and two commercial Bt suppliers, Abbott Laboratories...

  14. Evaluation of stem borer resistance management strategies for Bt ...

    African Journals Online (AJOL)

    Evaluation of stem borer resistance management strategies for Bt maize in Kenya based on alternative host refugia. ... However, for successful management of a refugia strategy, strict stewardship is required from appropriate government or community institutions. Key words: Refugia, cost-benefit analysis, Bt-maize, insect ...

  15. Reproduction of root knot nematode (Meloidogyne incognita) on Bt ...

    African Journals Online (AJOL)

    SARAH

    2013-09-30

    Sep 30, 2013 ... incognita in Bt cotton (06Z604D), isoline (99M03) and HART 89M (local non-Bt cotton cultivar) under greenhouse conditions. Methods and results: Plant height, number of squares/bolls, fresh shoot and root weight were determined before root knot nematode (RKN) screening at 90 and 180 days after ...

  16. Assessing the potential economic impact of Bacillus thuringiensis (Bt ...

    African Journals Online (AJOL)

    The Insect Resistant Maize for Africa (IRMA) project is currently developing Bt maize for Kenya. So far, Bt genes with resistance to Chilo partellus, Chilo orichalcociliellus, Eldana sacharina, and Sesamia calamistis, four of the five major stemborers were successfully incorporated into elite CIMMYT maize inbred line ...

  17. Segregation and expression of transgenes in the progenies of Bt ...

    African Journals Online (AJOL)

    DR. NJ TONUKARI

    2012-04-17

    Apr 17, 2012 ... rent progenies of Bt transgenic rice crosses to conventional rice varieties was analyzed by Western dot blotting. The samples derived from GUS positive plants of. Bt transgenic rice crossed to conventional rice varieties were found to produce a higher level of toxin protein, but with greater range of variation.

  18. Reproduction of root knot nematode ( Meloidogyne incognita ) on Bt ...

    African Journals Online (AJOL)

    ... application of findings: The study has demonstrated that Bt cotton (06Z604D) is susceptible to M. Incognita. The results indicate the importance of integrating nematode management practices such as the use of organic amendments and nematicides with other cultural practices in future Kenyan Bt cotton agroecosystems.

  19. Leaf tissue assay for lepidopteran pests of Bt cotton

    Science.gov (United States)

    Laboratory measurements of susceptibility to Bt toxins can be a poor indicator of the ability of an insect to survive on transgenic crops. We investigated the potential of using cotton leaf tissue for evaluating heliothine susceptibilities to two dual-gene Bt cottons. A preliminary study was conduct...

  20. Segregation and expression of transgenes in the progenies of Bt ...

    African Journals Online (AJOL)

    PCR, Southern blotting and Western dot blotting analysis confirmed that cry1Ab gene was transferred to the genome of conventional rice varieties and it was highly expressed in the different progenies of Bt rice crossed to conventional rice varieties. Among these lines, the highest Bt toxin protein content reached 2.88% of ...

  1. Comparison of rhizosphere properties as affected by different Bt- and non-Bt-cotton (Gossypium hirsutum L.) genotypes and fertilization.

    Science.gov (United States)

    Ahamd, Maqshoof; Abbasi, Waleed Mumtaz; Jamil, Moazzam; Iqbal, Muhammad; Hussain, Azhar; Akhtar, Muhammad Fakhar-U-Zaman; Nazli, Farheen

    2017-06-01

    Incorporation of genetically modified crops in the cropping system raises the need for studying the effect of these crops on the soil ecosystem. The current study aimed to compare the effect of Bacillus thuringiensis (Bt)- and non-Bt-cotton (Gossypium hirsutum L.) genotypes on rhizosphere properties under fertilized and unfertilized soil conditions. One non-Bt-cotton (IUB 75) and four Bt-cotton varieties (IUB-222, MM-58, IUB-13, FH-142) were sown in a Randomized Complete Block Design (RCBD) in a factorial fashion with three replications under unfertilized (T1) and fertilized (T2 at NPK 310-170-110 kg ha -1 ) soil conditions. The culturable soil bacterial population was recorded at flowering, boll opening, and harvesting stages, while other rhizosphere biological and chemical properties were recorded at harvesting. Results revealed that Bt-cotton genotypes IUB-222 and FH-142 showed significantly higher rhizosphere total nitrogen, NH 4 + -N, available phosphorus, and available potassium. Total organic carbon and microbial biomass carbon was also maximum in the rhizosphere of IUB-222 under fertilized conditions. Similarly, bacterial population (CFU g -1 ) at flowering stage and at harvesting was significantly higher in the rhizosphere of IUB-222 as compared to non-Bt- (IUB-75) and other Bt-cotton genotypes under same growth conditions. It showed that Bt genotypes can help in maintaining soil macronutrients (total nitrogen, available phosphorus, and available potassium) under proper nutrient management. Moreover, Bt-cotton genotypes seem to strengthen certain biological properties of the soil, thus increasing the growth and yield capability, maintaining available nutrients in the soil as compared to non-Bt cotton, while no harmful effects of Bt cotton on soil properties was detected.

  2. Exposure and nontarget effects of transgenic Bt corn debris in streams.

    Science.gov (United States)

    Jensen, Peter D; Dively, Galen P; Swan, Christopher M; Lamp, William O

    2010-04-01

    Corn (Zea mays L.) transformed with a gene from the bacterium Bacillus thuringiensis (Bt) comprises 49% of all corn in the United States. The input of senesced corn tissue expressing the Bt gene may impact stream-inhabiting invertebrates that process plant debris, especially trichopteran species related to the target group of lepidopteran pests. Our goal was to assess risk associated with transgenic corn debris entering streams. First, we show the input of corn tissue after harvest was extended over months in a stream. Second, using laboratory bioassays based on European corn borer [Ostrinia nubilalis (Hübner)], we found no bioactivity of Cry1Ab protein in senesced corn tissue after 2 wk of exposure to terrestrial or aquatic environments. Third, we show that Bt near-isolines modify growth and survivorship of some species of invertebrates. Of the four nontarget invertebrate species fed Bt near-isolines, growth of two closely related trichopterans was not negatively affected, whereas a tipulid crane fly exhibited reduced growth rates, and an isopod exhibited reduced growth and survivorship on the Cry1Ab near-isoline but not on the stacked Cry1Ab + Cry3Bb1 near-isoline. Because of lack of evidence of bioactivity of Bt after 2 wk and because of lack of nontarget effects on the stacked near-isoline, we suggest that tissue-mediated differences, and not the presence of the Cry1Ab protein, caused the different responses among the species. Overall, our results provide evidence that adverse effects to aquatic nontarget shredders involve complex interactions arising from plant genetics and environment that cannot be ascribed to the presence of Cry1Ab proteins.

  3. Dicty_cDB: FC-BT04 [Dicty_cDB

    Lifescience Database Archive (English)

    Full Text Available library) FC-BT04 (Link to dictyBase) - - - Contig-U16023-1 FC-BT04P (Link to Original site) FC-BT04F 661 FC-BT04Z...FC-BT04Z 667 FC-BT04P 1328 - - Show FC-BT04 Library FC (Link to library) Clone ID FC-BT04 (Link to dictyBase)...biol.tsukuba.ac.jp/CSM/FC/FC-BT/FC-BT04Q.Seq.d/ Representative seq. ID FC-BT04P (Link to Original site)...Representative DNA sequence >FC-BT04 (FC-BT04Q) /CSM/FC/FC-BT/FC-BT04Q.Seq.d/ AAATAGTGCTACCTTTATAAAA...significant alignments: (bits) Value FC-BT04 (FC-BT04Q) /CSM/FC/FC-BT/FC-BT04Q.Seq.d/ 2456 0.0 FC-BS23 (FC-BS23Q)

  4. Herbivore-induced chemical and molecular responses of the kelps Laminaria digitata and Lessonia spicata.

    Directory of Open Access Journals (Sweden)

    Andrés Ritter

    Full Text Available Kelps are founding species of temperate marine ecosystems, living in intertidal coastal areas where they are often challenged by generalist and specialist herbivores. As most sessile organisms, kelps develop defensive strategies to restrain grazing damage and preserve their own fitness during interactions with herbivores. To decipher some inducible defense and signaling mechanisms, we carried out metabolome and transcriptome analyses in two emblematic kelp species, Lessonia spicata from South Pacific coasts and Laminaria digitata from North Atlantic, when challenged with their main specialist herbivores. Mass spectrometry based metabolomics revealed large metabolic changes induced in these two brown algae following challenges with their own specialist herbivores. Targeted metabolic profiling of L. spicata further showed that free fatty acid (FFA and amino acid (AA metabolisms were particularly regulated under grazing. An early stress response was illustrated by the accumulation of Sulphur containing amino acids in the first twelve hours of herbivory pressure. At latter time periods (after 24 hours, we observed FFA liberation and eicosanoid oxylipins synthesis likely representing metabolites related to stress. Global transcriptomic analysis identified sets of candidate genes specifically induced by grazing in both kelps. qPCR analysis of the top candidate genes during a 48-hours time course validated the results. Most of these genes were particularly activated by herbivore challenge after 24 hours, suggesting that transcriptional reprogramming could be operated at this time period. We demonstrated the potential utility of these genes as molecular markers for herbivory by measuring their inductions in grazed individuals of field harvested L. digitata and L. spicata. By unravelling the regulation of some metabolites and genes following grazing pressure in two kelps representative of the two hemispheres, this work contributes to provide a set of

  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. Is There Any Interaction between Background Knowledge and Language Proficiency That Affects "TOEFL iBT"® Reading Performance? TOEFL iBT® Research Report. TOEFL iBT-18. ETS Research Report RR-12-22

    Science.gov (United States)

    Hill, Yao Zhang; Liu, Ou Lydia

    2012-01-01

    This study investigated the effect of the interaction between test takers' background knowledge and language proficiency on their performance on the "TOEFL iBT"® reading section. Test takers with the target content background knowledge (the focal groups) and those without (the reference groups) were identified for each of the 5 selected…

  7. Astylus atromaculatus (Coleoptera: Melyridae): abundance and role in pollen dispersal in Bt and non-Bt cotton in South Africa.

    Science.gov (United States)

    Pierre, Jacqueline; Hofs, Jean-Luc

    2010-10-01

    In South Africa, modified Bt (Cry1 Ac) cotton cultivars and organic ones coexist. This raises the question of the risk of dissemination of genetically modified (GM) pollen to non-GM crops by visiting insects. We inventoried the flower-visiting insects in Bt and non-Bt cotton fields of the South African Highveld region and investigated their role in pollen dispersal. Their diversity and abundance varied slightly among sites, with Astylus atromaculatus as the predominant insect on both Bt and non-Bt cotton flowers. The other major flower-visiting species were Apis mellifera and solitary Apidae. No differences were found in the abundance of each taxum between Bt and non-Bt cotton except for Scoliidae and Nitidulidae, which were scarce overall (Bt flowers in the central area of the field at one site. The pollen load on A. atromaculatus was as high as on Apis mellifera. Cage tests showed that A. atromaculatus can pollinate female cotton plants by transferring pollen from male donor plants. In the field, the flight range of this insect was generally short (25 m), but it can occasionally reach up to 200 m or even more. This study therefore highlights that A. atromaculatus, commonly regarded as a pest, could be an unexpected but efficient pollinator. Because its population density can be high, this species could mediate unwanted cotton pollen flow when distances between coexiting fields are not sufficient.

  8. Structure and Biosynthesis of the BT Peptide Antibiotic from Brevibacillus texasporus

    OpenAIRE

    Wu, Xiaofeng; Ballard, Johnathan; Jiang, Yi Wei

    2005-01-01

    We isolated a novel gram-positive bacterium, Brevibacillus texasporus, that produces an antibiotic, BT. BT is a group of related peptides that are produced by B. texasporus cells in response to nutrient limitation. We report here purification and determination of the structure of the most abundant BT isomer, BT1583. Amino acid composition and tandem mass spectrometry experiments yielded a partial BT1583 structure. The presence of ornithine and d-form residues in the partial BT1583 structure i...

  9. 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...

  10. 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.

  11. Bt cotton producing Cry1Ac and Cry2Ab does not harm two parasitoids, Cotesia marginiventris and Copidosoma floridanum

    Science.gov (United States)

    Cabbage looper, Trichoplusia ni, is an agricultural pest that feeds on >160 plant species in 36 families and is an important lepidopteran pest on many vegetable and greenhouse crops and some field crops. Although there are no commercial Bt vegetable or greenhouse crops, T. ni is a target of Bollgard...

  12. Parasitoid-specific induction of plant responses to parasitized herbivores affects colonization by subsequent herbivores.

    Science.gov (United States)

    Poelman, Erik H; Zheng, Si-Jun; Zhang, Zhao; Heemskerk, Nanda M; Cortesero, Anne-Marie; Dicke, Marcel

    2011-12-06

    Plants are exposed to a suite of herbivorous attackers that often arrive sequentially. Herbivory affects interactions between the host plants and subsequently attacking herbivores. Moreover, plants may respond to herbivory by emitting volatile organic compounds (VOCs) that attract carnivorous natural enemies of the herbivores. However, information borne by VOCs is ubiquitous and may attract carnivores, such as parasitoids, that differ in their effectiveness at releasing the plant from its herbivorous attackers. Furthermore, the development of parasitoids within their herbivorous hosts, attacking a given host plant, may influence the elicitation of defensive reactions in the host plant. This may, in turn, affect the behavior of subsequent herbivores attacking the host plant. Here, we show that the species identity of a parasitoid had a more significant effect on defense responses of Brassica oleracea plants than the species identity of the herbivorous hosts of the parasitoids. Consequently, B. oleracea plants that were damaged by caterpillars (Pieris spp.) parasitized by different parasitoid species varied in the degree to which diamondback moths (Plutella xylostella) selected the plants for oviposition. Attracting parasitoids in general benefitted the plants by reducing diamondback moth colonization. However, the species of parasitoid that parasitized the herbivore significantly affected the magnitude of this benefit by its species-specific effect on herbivore-plant interactions mediated by caterpillar regurgitant. Our findings show that information-mediated indirect defense may lead to unpredictable consequences for plants when considering trait-mediated effects of parasitized caterpillars on the host plant and their consequences because of community-wide responses to induced plants.

  13. Feeding niches of four large herbivores in the Hluhluwe Game ...

    African Journals Online (AJOL)

    ... communities; connochaetes taurinus taurinus; discriminant function analysis; equus burchelli burchelli; feeding; grass; grasses; habitat; herbivores; hluhluwe game reserve; kwazulu-natal; large herbivores; latent roots; natal; niche; niche overlap; niche separation; south africa; syncerus caffer caffer; white rhinoceros; ...

  14. Climate alters response of an endemic island plant to removal of invasive herbivores

    Science.gov (United States)

    Kathryn, Mceachern A.; Thomson, D.M.; Chess, K.A.

    2009-01-01

    -driven variation may counteract and mask positive responses to herbivore removal. Regional mean temperatures already have risen significantly over the last 50 years, suggesting that climate change could increasingly swamp the effects of management targeted at other environmental problems. Similar interactions between climate and invasive species will play an even greater role in future management, with long-term data sets like this critical to quantifying such effects. ?? 2009 by the Ecological Society of America.

  15. Cytotoxicity of the Bacillus thuringiensis Cry4B toxin is mediated by the cadherin receptor BT-R₃ of Anopheles gambiae.

    Science.gov (United States)

    Ibrahim, Mohamed A; Griko, Natalya B; Bulla, Lee A

    2013-07-01

    We demonstrate for the first time the selective cytotoxicity of Bacillus thuringiensis subsp. israelensis Cry4B toxin mediated by BT-R₃ using a cell-based system, which employs High Five insect cells stably expressing BT-R₃. Discovery and validation of BT-R₃ as the Cry4B receptor was accomplished using a web-based computational pipeline platform that facilitates high-throughput insecticidal target identification utilizing the Anopheles gambiae genome. Once the Cry4B toxin binds to the BT-R₃ receptor, a cell death pathway is manifested by sequential cytological changes that include membrane blebbing, cell swelling and lysis. Cry4B toxin associates with cell membrane in both oligomeric and monomeric forms. Monomeric toxin binds specifically to BT-R₃ whereas oligomer interacts with cell membrane non-specifically. Cytotoxicity and cell death are the direct result of binding of toxin monomer to BT-R₃. The oligomeric form of Cry4B toxin is not involved in cell death. Both the location of the toxin-binding region within BT-R₃ and its structural motif are critical to the binding affinity and specificity of the toxin. The toxin-binding region of BT-R₃ appears to be located in EC11, the most membrane proximal EC module within the extracellular domain. It is characterized by the presence of two highly conserved amino acid sequences within their N- and C-termini that flank EC11. These sequences represent signature motifs that mark the toxin-binding function in BT-R₃. The two sequences form two adjacent β-strands within the β-barrel of EC11, the positioning of which is a hallmark of all Cry toxin receptors thus far reported.

  16. 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.

  17. Effect of Bt-176 maize pollen on first instar larvae of the Peacock butterfly (Inachis io) (Lepidoptera; Nymphalidae).

    Science.gov (United States)

    Felke, Martin; Langenbruch, Gustav-Adolf; Feiertag, Simon; Kassa, Adane

    2010-01-01

    More than 10 years after registration of the first Bt maize cultivar in Europe, there still exists a remarkable lack of data on effects on Lepidoptera which would be necessary for a complete and comprehensive environmental risk assessment. So far only very few European butterfly species have been tested in this aspect. In our study the effect of transgenic Bacillus thuringiensis (Bt) maize pollen (event Bt-176) on the development and survival of neonate larvae of the Peacock butterfly, Inachis io (L.) was for the first time shown. The results of our study suggest that the Peacock butterfly may serve as a model organism for assessing potential side effects of new developed transgenic Bt crops on non-target butterflies in a GMO environmental risk assessment. The study was done under laboratory conditions by exposing larvae of the Peacock butterfly to various pollen doses of transgenic maize event Bt-176 (cv. PACTOL CB) or the conventional isogenic maize (cv. PACTOL) using a no-choice test. Larvae feeding for 48 h on nettle plants (Urtica dioica) that were contaminated with higher pollen concentrations from Bt-176 maize (205 and 388 applied pollen.cm⁻²) suffered a significantly higher mortality rate (68 and 85% respectively) compared to larvae feeding on leaves with no pollen (11%), or feeding on leaves with pollen from conventional maize (6 to 25%). At lower Bt maize pollen doses (23-104 applied pollen.cm⁻²),mortality ranged from 11-25% and there were no apparent differences among treatments. The corresponding LC₅₀-and LC₉₀-values for neonate larvae of the Peacock butterfly were 187 and 448 applied pollen grains.cm⁻² of Bt-176, respectively.Weight of larvae surviving consumption of Bt-176 maize pollen declined between 10 and 81% with increased pollen doses (r = -0.95). The highest weight reduction (81%) corresponded to the highest pollen concentration (388 pollen grains applied.cm⁻²). Ingestion of pollen from the conventional maize hybrid did not

  18. Monitoring of Bt11 and Bt176 genetically modified maize in food sold commercially in Brazil from 2005 to 2007.

    Science.gov (United States)

    Dinon, Andréia Z; Bosco, Kenia T; Arisi, Ana Carolina M

    2010-07-01

    The first genetically modified (GM) maize lines were approved for trading in Brazil after December 2007 and they were T25, MON810, Bt11, NK603 and GA21. The polymerase chain reaction (PCR) method was employed to monitor the presence of Bt11 and nested PCR was used to detect the presence of Bt176 in 81 maize-derived products (maize flour, corn meal, maize flour flakes and polenta) that were sold in Brazilian market from 2005 to 2007, before the release of GM maize in Brazil. The PCR detection limit for Bt11 was 10 g kg(-1) and for nested PCR of Bt176 it was 1 g kg(-1). All Brazilian samples analyzed showed no positive signal for these GM maize events. Bt11 and Bt176 GM maize lines were not detected by specific PCR in 81 maize-derived food samples sold in Brazil from 2005 to 2007, before the commercial release of GM maize in Brazil. These Brazilian food industries were in compliance with the rules stipulated by the current legislation with respect to consumer requirements about GMO labeling.

  19. Herbivore impact on grassland plant diversity depends on habitat productivity and herbivore size

    NARCIS (Netherlands)

    Bakker, ES; Ritchie, ME; Olff, H; Milchunas, DG; Knops, JMH; Bakker, Elisabeth S.; Ritchie, Mark E.; Milchunas, Daniel G.; Knops, Johannes M.H.; Waller, Don

    Mammalian herbivores can have pronounced effects on plant diversity but are currently declining in many productive ecosystems through direct extirpation, habitat loss and fragmentation, while being simultaneously introduced as livestock in other, often unproductive, ecosystems that lacked such

  20. Herbivore impact on grassland plant diversity depends on habitat productivity and herbivore size

    NARCIS (Netherlands)

    Bakker, E.S.; Ritchie, M.E.; Olff, H.; Milchunas, D.G.; Knops, J.M.H.

    2006-01-01

    Mammalian herbivores can have pronounced effects on plant diversity but are currently declining in many productive ecosystems through direct extirpation, habitat loss and fragmentation, while being simultaneously introduced as livestock in other, often unproductive, ecosystems that lacked such

  1. Herbivore impact on grassland plant diversity depens on habitat productivity and herbivore size.

    NARCIS (Netherlands)

    Bakker, E.S.; Ritchie, M.E.; Olff, H.; Milchunas, D.G.; Knops, J.M.H.

    2006-01-01

    Mammalian herbivores can have pronounced effects on plant diversity but are currently declining in many productive ecosystems through direct extirpation, habitat loss and fragmentation, while being simultaneously introduced as livestock in other, often unproductive, ecosystems that lacked such

  2. Land‐use history alters contemporary insect herbivore community composition and decouples plant–herbivore relationships

    National Research Council Canada - National Science Library

    Hahn, Philip G; Orrock, John L; Behmer, Spencer

    2015-01-01

    ...‐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...

  3. Evaluating herbivore extinction probabilities in Addo Elephant ...

    African Journals Online (AJOL)

    . (1991) that did not take density dependence into account and that were based on census data, suggest that many of the herbivore species in Addo Elephant National Park (AENP) are vulnerable to local extinction. As a result of low ...

  4. Cellular responses in Bacillus thuringiensis CS33 during bacteriophage BtCS33 infection.

    Science.gov (United States)

    Wu, Dandan; Yuan, Yihui; Liu, Pengming; Wu, Yan; Gao, Meiying

    2014-04-14

    Bacillus thuringiensis (Bt) has been widely used for 50years as a biopesticide for controlling insect pests. However, bacteriophage infection can cause failures in 50%-80% of the batches during Bt fermentation, resulting in severe losses. In the present work, the physiological and biochemical impacts of Bt strain CS33 have been studied during bacteriophage infection. This study adopted a gel-based proteomics approach to probe the sequential changed proteins in phage-infected Bt cells. To phage, it depressed the host energy metabolism by suppressing the respiration chain, the TCA cycle, and the utilization of PHB on one hand; on the other hand, it hijacked the host translational machine for its own macromolecular synthesis. To host, superinfection exclusion might be triggered by the changes of S-layer protein and flagella related proteins, which were located on the cell surface and might play as the candidates for the phage recognition. More importantly, the growth rate, cell mass, and ICPs yield were significantly decreased. The low yield of ICPs was mainly due to the suppressed utilization of PHB granules. Further functional study on these altered proteins may lead to a better understanding of the pathogenic mechanisms and the identification of new targets for phage control. B. thuringiensis (Bt) has been widely used for 50years as a safe biopesticide for controlling agricultural and sanitary insect pests. However, bacteriophage infection can cause severe losses during B. thuringiensis fermentation. The processes and consequences of interactions between bacteriophage and Bt were still poorly understood, and the molecular mechanisms involved were more unknown. This study adopted a gel-based proteomics approach to probe the physiological and biochemical impacts of Bt strain CS33 after phage-infection. The interactions between phage BtCS33 and its host Bt strain CS33 occurred mainly on four aspects. First, phage synthesized its nucleic acids through metabolic

  5. Invasive insect herbivores as disrupters of chemically-mediated tritrophic interactions: effects of herbivore density and parasitoid learning

    Science.gov (United States)

    Invasive species of insect herbivores have the potential to interfere with native multitrophic interactions when they invade new environments. For instance, exotic herbivores can affect the chemical cues emitted by plants and disrupt attraction of natural enemies mediated by herbivore-induced plant ...

  6. Harmonia axyridis (Coleoptera: Coccinellidae exhibits no preference between Bt and non-Bt maize fed Spodoptera frugiperda (Lepidoptera: Noctuidae.

    Directory of Open Access Journals (Sweden)

    Carla C Dutra

    Full Text Available A recent shift in managing insect resistance to genetically engineered (GE maize consists of mixing non-GE seed with GE seed known as "refuge in a bag", which increases the likelihood of predators encountering both prey fed Bt and prey fed non-Bt maize. We therefore conducted laboratory choice-test feeding studies to determine if a predator, Harmonia axyridis, shows any preference between prey fed Bt and non-Bt maize leaves. The prey species was Spodoptera frugiperda, which were fed Bt maize (MON-810, expressing the single Cry1Ab protein, or non-Bt maize. The predators were third instar larvae and female adults of H. axyridis. Individual predators were offered Bt and non-Bt fed prey larvae that had fed for 24, 48 or 72 h. Ten and 15 larvae of each prey type were offered to third instar and adult predators, respectively. Observations of arenas were conducted at 1, 2, 3, 6, 15 and 24 h after the start of the experiment to determine the number and type of prey eaten by each individual predator. Prey larvae that fed on non-Bt leaves were significantly larger than larvae fed Bt leaves. Both predator stages had eaten nearly all the prey by the end of the experiment. However, in all combinations of predator stage and prey age, the number of each prey type consumed did not differ significantly. ELISA measurements confirmed the presence of Cry1Ab in leaf tissue (23-33 µg/g dry weight and S. frugiperda (2.1-2.2 µg/g, while mean concentrations in H. axyridis were very low (0.01-0.2 µg/g. These results confirm the predatory status of H. axyridis on S. frugiperda and that both H. axyridis adults and larvae show no preference between prey types. The lack of preference between Bt-fed and non-Bt-fed prey should act in favor of insect resistance management strategies using mixtures of GE and non-GE maize seed.

  7. 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.

  8. Effects of ensiling of Bacillus thuringiensis (Bt) maize (MON810) on ...

    African Journals Online (AJOL)

    The study investigated the degradation of the Bt protein (Cry1Ab) in Bt maize during ensiling and chemical composition of the silage. Two laboratory studies were conducted at the University of Fort Hare. One Bacillus thuringiensis (Bt) maize cultivar (DKC80-12B) and its isoline (DKC80-10) in the 2008/2009 study and two Bt ...

  9. Developing Analytic Rating Guides for "TOEFL iBT"® Integrated Speaking Tasks. "TOEFL iBT"® Research Report, TOEFL iBT-20. ETS Research Report. RR-13-13

    Science.gov (United States)

    Jamieson, Joan; Poonpon, Kornwipa

    2013-01-01

    Research and development of a new type of scoring rubric for the integrated speaking tasks of "TOEFL iBT"® are described. These "analytic rating guides" could be helpful if tasks modeled after those in TOEFL iBT were used for formative assessment, a purpose which is different from TOEFL iBT's primary use for admission…

  10. Insect Resistance Management in Bt Maize: Wild Host Plants of Stem Borers Do Not Serve as Refuges in Africa.

    Science.gov (United States)

    Van den Berg, J

    2017-02-01

    Resistance evolution by target pests threatens the sustainability of Bt maize in Africa where insect resistance management (IRM) strategies are faced by unique challenges. The assumptions, on which current IRM strategies for stem borers are based, are not all valid for African maize stem borer species. The high dose-refuge strategy which is used to delay resistance evolution relies heavily on the presence of appropriate refuges (non-Bt plants) where pests are not under selection pressure and where sufficient numbers of Bt-susceptible individuals are produced to mate with possible survivors on the Bt maize crop. Misidentification of stem borer species and inaccurate reporting on wild host plant diversity over the past six decades created the perception that grasses will contribute to IRM strategies for these pests in Africa. Desired characteristics of refuge plants are that they should be good pest hosts, implying that larval survival is high and that it produces sufficient numbers of high-quality moths. Refuge plants should also have large cover abundance in areas where Bt maize is planted. While wild host plants may suffice in IRM strategies for polyphagous pests, this is not the case with stenophagous pests. This review discusses data of ecological studies and stem borer surveys conducted over the past decade and shows that wild host plants are unsuitable for development and survival of sufficient numbers of stem borer individuals. These grasses rather act as dead-end-trap plants and do not comply with refuge requirements of producing 500 susceptible individuals for every one resistant individual that survives on Bt maize. © The Authors 2016. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. 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.

  12. 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.

  13. Transgenic Bt rice lines producing Cry1Ac, Cry2Aa or Cry1Ca have no detrimental effects on Brown Planthopper and Pond Wolf Spider.

    Science.gov (United States)

    Niu, Lin; Mannakkara, Amani; Qiu, Lin; Wang, Xiaoping; Hua, Hongxia; Lei, Chaoliang; Jurat-Fuentes, Juan Luis; Ma, Weihua

    2017-05-16

    Transgenic rice expressing cry genes from the bacterium Bacillus thuringiensis (Bt rice) is highly resistant to lepidopteran pests. The brown planthopper (BPH, Nilaparvata lugens) is the main non-target sap-sucking insect pest of Bt transgenic rice. The pond wolf spider (PWS, Pardosa pseudoannulata) is one of the most dominant predators of BPH in rice fields. Consequently, the safety evaluation of Bt rice on BPH and PWS should be conducted before commercialization. In the current study, two experiments were performed to assess the potential ecological effects of Bt rice on BPH and PWS: (1) a tritrophic experiment to evaluate the transmission of Cry1Ac, Cry2Aa and Cry1Ca protein in the food chain; and (2) binding assays of Cry1Ac, Cry2Aa and Cry1Ca to midgut brush border membrane proteins from BPH and PWS. Trace amounts of the three Cry proteins were detected in BPH feeding on Bt rice cultivars, but only Cry1Ac and Cry2Aa proteins could be transferred to PWS through feeding on BPH. In vitro binding of biotinylated Cry proteins and competition assays in midgut protein vesicles showed weak binding, and ligand blot analysis confirmed the binding specificity. Thus, we inferred that the tested Bt rice varieties have negligible effects on BPH and PWS.

  14. Bt crops producing Cry1Ac, Cry2Ab and Cry1F do not harm the green lacewing, Chrysoperla rufilabris.

    Directory of Open Access Journals (Sweden)

    Jun-Ce Tian

    Full Text Available The biological control function provided by natural enemies is regarded as a protection goal that should not be harmed by the application of any new pest management tool. Plants producing Cry proteins from the bacterium, Bacillus thuringiensis (Bt, have become a major tactic for controlling pest Lepidoptera on cotton and maize and risk assessment studies are needed to ensure they do not harm important natural enemies. However, using Cry protein susceptible hosts as prey often compromises such studies. To avoid this problem we utilized pest Lepidoptera, cabbage looper (Trichoplusia ni and fall armyworm (Spodoptera frugiperda, that were resistant to Cry1Ac produced in Bt broccoli (T. ni, Cry1Ac/Cry2Ab produced in Bt cotton (T. ni, and Cry1F produced in Bt maize (S. frugiperda. Larvae of these species were fed Bt plants or non-Bt plants and then exposed to predaceous larvae of the green lacewing Chrysoperla rufilabris. Fitness parameters (larval survival, development time, fecundity and egg hatch of C. rufilabris were assessed over two generations. There were no differences in any of the fitness parameters regardless if C. rufilabris consumed prey (T. ni or S. frugiperda that had consumed Bt or non-Bt plants. Additional studies confirmed that the prey contained bioactive Cry proteins when they were consumed by the predator. These studies confirm that Cry1Ac, Cry2Ab and Cry1F do not pose a hazard to the important predator C. rufilabris. This study also demonstrates the power of using resistant hosts when assessing the risk of genetically modified plants on non-target organisms.

  15. Bt crops producing Cry1Ac, Cry2Ab and Cry1F do not harm the green lacewing, Chrysoperla rufilabris.

    Science.gov (United States)

    Tian, Jun-Ce; Wang, Xiang-Ping; Long, Li-Ping; Romeis, Jörg; Naranjo, Steven E; Hellmich, Richard L; Wang, Ping; Earle, Elizabeth D; Shelton, Anthony M

    2013-01-01

    The biological control function provided by natural enemies is regarded as a protection goal that should not be harmed by the application of any new pest management tool. Plants producing Cry proteins from the bacterium, Bacillus thuringiensis (Bt), have become a major tactic for controlling pest Lepidoptera on cotton and maize and risk assessment studies are needed to ensure they do not harm important natural enemies. However, using Cry protein susceptible hosts as prey often compromises such studies. To avoid this problem we utilized pest Lepidoptera, cabbage looper (Trichoplusia ni) and fall armyworm (Spodoptera frugiperda), that were resistant to Cry1Ac produced in Bt broccoli (T. ni), Cry1Ac/Cry2Ab produced in Bt cotton (T. ni), and Cry1F produced in Bt maize (S. frugiperda). Larvae of these species were fed Bt plants or non-Bt plants and then exposed to predaceous larvae of the green lacewing Chrysoperla rufilabris. Fitness parameters (larval survival, development time, fecundity and egg hatch) of C. rufilabris were assessed over two generations. There were no differences in any of the fitness parameters regardless if C. rufilabris consumed prey (T. ni or S. frugiperda) that had consumed Bt or non-Bt plants. Additional studies confirmed that the prey contained bioactive Cry proteins when they were consumed by the predator. These studies confirm that Cry1Ac, Cry2Ab and Cry1F do not pose a hazard to the important predator C. rufilabris. This study also demonstrates the power of using resistant hosts when assessing the risk of genetically modified plants on non-target organisms.

  16. Herbivore release through cascading risk effects.

    Science.gov (United States)

    Schmidt-Entling, Martin H; Siegenthaler, Eva

    2009-12-23

    Predators influence prey through consumption, and through trait-mediated effects such as emigration in response to predation risk (risk effects). We studied top-down effects of (sub-) adult wolf spiders (Lycosidae) on arthropods in a meadow. We compared risk effects with the overall top-down effect (including consumption) by gluing the chelicers of wolf spiders to prevent them from killing the prey. In a field experiment, we created three treatments that included either: (i) intact ('predation') wolf spiders; (ii) wolf spiders with glued chelicers ('risk spiders'); or (iii) no (sub-) adult wolf spiders. Young wolf spiders were reduced by their (sub-) adult congeners. Densities of sheetweb spiders (Linyphiidae), a known intraguild prey of wolf spiders, were equally reduced by the presence of risk and predation wolf spiders. Plant- and leafhoppers (Auchenorrhyncha) showed the inverse pattern of higher densities in the presence of both risk and predation wolf spiders. We conclude that (sub-) adult wolf spiders acted as top predators, which reduced densities of intermediate predators and thereby enhanced herbivores. Complementary to earlier studies that found trait-mediated herbivore suppression, our results demonstrate that herbivores can be enhanced through cascading risk effects by top predators.

  17. 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

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

    Science.gov (United States)

    Amo, Luisa; Jansen, Jeroen J; van Dam, Nicole M; Dicke, Marcel; Visser, Marcel E

    2013-11-01

    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 insects such as lepidopteran larvae. Here, we show that great tits (Parus major) discriminate between caterpillar-infested and uninfested trees. Birds were attracted to infested trees, even when they could not see the larvae or their feeding damage. We furthermore show that infested and uninfested trees differ in volatile emissions and visual characteristics. Finally, we show, for the first time, that birds smell which tree is infested with their prey based on differences in volatile profiles emitted by infested and uninfested trees. Volatiles emitted by plants in response to herbivory by lepidopteran larvae thus not only attract predatory insects but also vertebrate predators. © 2013 John Wiley & Sons Ltd/CNRS.

  19. Feeding and dispersal behavior of the cotton leafworm, Alabama argillacea (Hübner) (Lepidoptera: Noctuidae), on Bt and non-Bt cotton: implications for evolution and resistance management.

    Science.gov (United States)

    Ramalho, Francisco S; Pachú, Jéssica K S; Lira, Aline C S; Malaquias, José B; Zanuncio, José C; Fernandes, Francisco S

    2014-01-01

    The host acceptance of neonate Alabama argillacea (Hübner) (Lepidoptera: Noctuidae) larvae to Bt cotton plants exerts a strong influence on the potential risk that this pest will develop resistance to Bt cotton. This will also determine the efficiency of management strategies to prevent its resistance such as the "refuge-in-the-bag" strategy. In this study, we assessed the acceptance of neonate A. argillacea larvae to Bt and non-Bt cotton plants at different temperatures during the first 24 h after hatching. Two cotton cultivars were used in the study, one a Bt DP 404 BG (Bollgard) cultivar, and the other, an untransformed isoline, DP 4049 cultivar. There was a greater acceptance by live neonate A. argillacea larvae for the non-Bt cotton plants compared with the Bt cotton plants, especially in the time interval between 18 and 24 h. The percentages of neonate A. argillacea larvae found on Bt or non-Bt plants were lower when exposed to temperatures of 31 and 34 °C. The low acceptance of A. argillacea larvae for Bt cotton plants at high temperatures stimulated the dispersion of A. argillacea larvae. Our results support the hypothesis that the dispersion and/or feeding behavior of neonate A. argillacea larvae is different between Bt and non-Bt cotton. The presence of the Cry1Ac toxin in Bt cotton plants, and its probable detection by the A. argillacea larvae tasting or eating it, increases the probability of dispersion from the plant where the larvae began. These findings may help to understand how the A. argillacea larvae detect the Cry1Ac toxin in Bt cotton and how the toxin affects the dispersion behavior of the larvae over time. Therefore, our results are extremely important for the management of resistance in populations of A. argillacea on Bt cotton.

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

    Science.gov (United States)

    Gilbert, Lucy; Johnson, David

    2015-08-01

    Plants mediate indirect 'apparent' effects between above-ground herbivores and below-ground mutualistic mycorrhizal fungi. The herbivore-plant-mycorrhiza continuum is further complicated because signals produced by plants in response to herbivores can be transmitted to other plants via shared fungal networks below ground. Insect herbivores, such as aphids, probably affect the functioning of mycorrhizal fungi by changing the supply of recent photosynthate from plants to mycorrhizas, whereas there is evidence that mycorrhizas affect aphid fitness by changing plant signalling pathways, rather than only through improved nutrition. New knowledge of the transfer of signals through fungal networks between plant species means we now need a better understanding of how this process occurs in relation to the feeding preferences of herbivores to shape plant community composition and herbivore behaviour in nature. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Science.gov (United States)

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

    2013-08-01

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

  2. 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

  3. Endophyte mediated plant-herbivore interactions or cross resistance to fungi and insect herbivores

    Science.gov (United States)

    Kari Saikkonen; Marjo Helander

    2012-01-01

    Endophytic fungi are generally considered to be plant mutualists that protect the host plant from pathogens and herbivores. Defensive mutualism appears to hold true particularly for seed-transmitted, alkaloid producing, grass endophytes. However, we propose that the mutualistic nature of plant-endophyte interactions via enhanced plant resistance to pathogens and...

  4. Dual herbivore attack and herbivore density affect metabolic profiles of Brassica nigra leaves

    NARCIS (Netherlands)

    Ponzio, Camille; Papazian, Stefano; Albrectsen, Benedicte R.; Dicke, Marcel; Gols, Rieta

    2017-01-01

    Plant responses to dual herbivore attack are increasingly studied, but effects on the metabolome have largely been restricted to volatile metabolites and defence-related non-volatile metabolites. However, plants subjected to stress, such as herbivory, undergo major changes in both primary and

  5. Regulation of the seasonal population patterns of Helicoverpa armigera moths by Bt cotton planting.

    Science.gov (United States)

    Gao, Yu-Lin; Feng, Hong-Qiang; Wu, Kong-Ming

    2010-08-01

    Transgenic cotton expressing the Bacillus thuringiensis (Bt) Cry1Ac toxin has been commercially cultivated in China since 1997, and by 2000 Bt cotton had almost completely replaced non-transgenic cotton cultivars. To evaluate the impact of Bt cotton planting on the seasonal population patterns of cotton bollworm, Helicoverpa armigera, the dynamics of H. armigera moths were monitored with light traps from four locations (Xiajin, Linqing and Dingtao of Shandong Province; Guantao of Hebei Province) in high Bt density region and five locations (Anci and Xinji of Hebei Province; Dancheng and Fengqiu of Henan Province; Gaomi of Shandong Province) in low Bt density region from 1996 to 2008. A negative correlation was found between moth densities of H. armigera and the planting years of Bt cotton in both high and low Bt density areas. These data indicate that the moth population density of H. armigera was reduced with the introduction of Bt cotton in northern China. Three generations of moths occurred between early June and late September in the cotton regions. Interestingly, second-generation moths decreased and seemed to vanish in recent years in high Bt density region, but this tendency was not found in low Bt density region. The data suggest that the planting of Bt cotton in high Bt density region was effective in controlling the population density of second-generation moths. Furthermore, the seasonal change of moth patterns associated with Bt cotton planting may regulate the regional occurrence and population development of this migratory insect.

  6. Breeding and Characterization of a New Rice Restorer Line Containing Bt Gene

    Directory of Open Access Journals (Sweden)

    Fang-yuan GAO

    2009-09-01

    Full Text Available Bt5198, a new rice restorer line containing Bt gene, was developed from the cross and backcross of the elite restorer line Chenghui 177 with Bt Minghui 63, a transgenic Bt restorer line. The inbred lines were evaluated using PCR amplification, test paper evaluation, insect resistance evaluation in both the laboratory and paddy fields, nursery evaluation of rice blast resistance and pedigree selection of agronomic traits. Larval mortalities on Bt5198 and Bt Minghui 63 were 100% when rice culms were inoculated with the eggs of the striped stem borer (SSB in the laboratory. Bt5198 was highly resistant against SSB and the yellow stem borer (YSB under field conditions. The F1 hybrids derived from Bt5198 and four cytoplasmic male sterile (CMS lines were also highly resistant to SSB and YSB and had a significant heterosis. Two-year evaluation of rice blast resistance confirmed that the resistance levels of Bt5198 to leaf blast and neck blast were similar to those of Chenghui 177 and significantly better than those of Bt Minghui 63. Seed germination ability and pollen yield of Bt5198 were similar with Chenghui 177, suggesting that the introduction of the Bt gene into the new restorer line had no significant effects on seed vitality or the yield of seed production. To identify the presence of the Bt gene, it was effective to combine test paper examination with the evaluation of insect-resistance, both in the laboratory and under field conditions.

  7. Tannins in plant-herbivore interactions.

    Science.gov (United States)

    Barbehenn, Raymond V; Peter Constabel, C

    2011-09-01

    Tannins are the most abundant secondary metabolites made by plants, commonly ranging from 5% to 10% dry weight of tree leaves. Tannins can defend leaves against insect herbivores by deterrence and/or toxicity. Contrary to early theories, tannins have no effect on protein digestion in insect herbivores. By contrast, in vertebrate herbivores tannins can decrease protein digestion. Tannins are especially prone to oxidize in insects with high pH guts, forming semiquinone radicals and quinones, as well as other reactive oxygen species. Tannin toxicity in insects is thought to result from the production of high levels of reactive oxygen species. Tannin structure has an important effect on biochemical activity. Ellagitannins oxidize much more readily than do gallotannins, which are more oxidatively active than most condensed tannins. The ability of insects to tolerate ingested tannins comes from a variety of biochemical and physical defenses in their guts, including surfactants, high pH, antioxidants, and a protective peritrophic envelope that lines the midgut. Most work on the ecological roles of tannins has been correlative, e.g., searching for negative associations between tannins and insect performance. A greater emphasis on manipulative experiments that control tannin levels is required to make further progress on the defensive functions of tannins. Recent advances in the use of molecular methods has permitted the production of tannin-overproducing transgenic plants and a better understanding of tannin biosynthetic pathways. Many research areas remain in need of further work, including the effects of different tannin types on different types of insects (e.g., caterpillars, grasshoppers, sap-sucking insects). Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. A test of genotypic variation in specificity of herbivore-induced responses in Solidago altissima L. (Asteraceae)

    NARCIS (Netherlands)

    Uesugi, A.; Poelman, E.H.; Kessler, A.

    2013-01-01

    Plant-induced responses to multiple herbivores can mediate ecological interactions among herbivore species, thereby influencing herbivore community composition in nature. Several studies have indicated high specificity of induced responses to different herbivore species. In addition, there may be

  9. Herbivore regulation of plant abundance in aquatic ecosystems.

    Science.gov (United States)

    Wood, Kevin A; O'Hare, Matthew T; McDonald, Claire; Searle, Kate R; Daunt, Francis; Stillman, Richard A

    2017-05-01

    Herbivory is a fundamental process that controls primary producer abundance and regulates energy and nutrient flows to higher trophic levels. Despite the recent proliferation of small-scale studies on herbivore effects on aquatic plants, there remains limited understanding of the factors that control consumer regulation of vascular plants in aquatic ecosystems. Our current knowledge of the regulation of primary producers has hindered efforts to understand the structure and functioning of aquatic ecosystems, and to manage such ecosystems effectively. We conducted a global meta-analysis of the outcomes of plant-herbivore interactions using a data set comprised of 326 values from 163 studies, in order to test two mechanistic hypotheses: first, that greater negative changes in plant abundance would be associated with higher herbivore biomass densities; second, that the magnitude of changes in plant abundance would vary with herbivore taxonomic identity. We found evidence that plant abundance declined with increased herbivore density, with plants eliminated at high densities. Significant between-taxa differences in impact were detected, with insects associated with smaller reductions in plant abundance than all other taxa. Similarly, birds caused smaller reductions in plant abundance than echinoderms, fish, or molluscs. Furthermore, larger reductions in plant abundance were detected for fish relative to crustaceans. We found a positive relationship between herbivore species richness and change in plant abundance, with the strongest reductions in plant abundance reported for low herbivore species richness, suggesting that greater herbivore diversity may protect against large reductions in plant abundance. Finally, we found that herbivore-plant nativeness was a key factor affecting the magnitude of herbivore impacts on plant abundance across a wide range of species assemblages. Assemblages comprised of invasive herbivores and native plant assemblages were associated with

  10. (SSR) marker- assisted genetic diversity among upland Bt- and non ...

    African Journals Online (AJOL)

    Student

    2011-11-02

    Nov 2, 2011 ... new elite cotton cultivars. Key words: Bt-cotton, dissimilarity matrix, DNA polymorphism, genetic diversity, SSR marker. INTRODUCTION. Cotton is the world's most imperative natural textile fiber and a valuable oil seed crop. Cotton is the main cash crop of Pakistan and provides cotton fiber to the national.

  11. Evaluation of bioassays for testing Bt sweetpotato events against ...

    African Journals Online (AJOL)

    In addition, this method was the most labour intensive in terms of frequent replacement of root chips for weevil development. Hence, the most appropriate method for testing Bt efficacy in sweetpotato is the small root egg-plug bioassay. Nonetheless, none of the transgenic events tested provided weevil control probably ...

  12. Management practices to control premature senescence in bt cotton

    Science.gov (United States)

    Commercial cultivation of Bt cotton produced higher boll load which led to stiff inter-organal competition for photosynthates resulting in early cessation of growth (premature senescence) due to more availability of sink and less sources. To overcome this problem field experiment was conducted durin...

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

    OpenAIRE

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

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

    National Research Council Canada - National Science Library

    Zhang, Haonan; Yin, Wei; Zhao, Jing; Jin, Lin; Yang, Yihua; Wu, Shuwen; Tabashnik, Bruce E; Wu, Yidong

    2011-01-01

    .... 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...

  15. Effects of Soil Salinity on the Expression of Bt Toxin (Cry1Ac and the Control Efficiency of Helicoverpa armigera in Field-Grown Transgenic Bt Cotton.

    Directory of Open Access Journals (Sweden)

    Jun-Yu Luo

    Full Text Available An increasing area of transgenic Bacillus thuringiensis (Bt cotton is being planted in saline-alkaline soil in China. The Bt protein level in transgenic cotton plants and its control efficiency can be affected by abiotic stress, including high temperature, water deficiency and other factors. However, how soil salinity affects the expression of Bt protein, thus influencing the control efficiency of Bt cotton against the cotton bollworm (CBW Helicoverpa armigera (Hübner in the field, is poorly understood. Our objective in the present study was to investigate the effects of soil salinity on the expression of Bt toxin (Cry1Ac and the control efficiency of Helicoverpa armigera in field-grown transgenic Bt cotton using three natural saline levels (1.15 dS m-1 [low soil-salinity], 6.00 dS m-1 [medium soil-salinity] and 11.46 dS m-1 [high soil-salinity]. We found that the Bt protein content in the transgenic Bt cotton leaves and the insecticidal activity of Bt cotton against CBW decreased with the increasing soil salinity in laboratory experiments during the growing season. The Bt protein content of Bt cotton leaves in the laboratory were negatively correlated with the salinity level. The CBW populations were highest on the Bt cotton grown in medium-salinity soil instead of the high-salinity soil in field conditions. A possible mechanism may be that the relatively high-salinity soil changed the plant nutritional quality or other plant defensive traits. The results from this study may help to identify more appropriate practices to control CBW in Bt cotton fields with different soil salinity levels.

  16. Effects of Soil Salinity on the Expression of Bt Toxin (Cry1Ac) and the Control Efficiency of Helicoverpa armigera in Field-Grown Transgenic Bt Cotton.

    Science.gov (United States)

    Luo, Jun-Yu; Zhang, Shuai; Peng, Jun; Zhu, Xiang-Zhen; Lv, Li-Min; Wang, Chun-Yi; Li, Chun-Hua; Zhou, Zhi-Guo; Cui, Jin-Jie

    2017-01-01

    An increasing area of transgenic Bacillus thuringiensis (Bt) cotton is being planted in saline-alkaline soil in China. The Bt protein level in transgenic cotton plants and its control efficiency can be affected by abiotic stress, including high temperature, water deficiency and other factors. However, how soil salinity affects the expression of Bt protein, thus influencing the control efficiency of Bt cotton against the cotton bollworm (CBW) Helicoverpa armigera (Hübner) in the field, is poorly understood. Our objective in the present study was to investigate the effects of soil salinity on the expression of Bt toxin (Cry1Ac) and the control efficiency of Helicoverpa armigera in field-grown transgenic Bt cotton using three natural saline levels (1.15 dS m-1 [low soil-salinity], 6.00 dS m-1 [medium soil-salinity] and 11.46 dS m-1 [high soil-salinity]). We found that the Bt protein content in the transgenic Bt cotton leaves and the insecticidal activity of Bt cotton against CBW decreased with the increasing soil salinity in laboratory experiments during the growing season. The Bt protein content of Bt cotton leaves in the laboratory were negatively correlated with the salinity level. The CBW populations were highest on the Bt cotton grown in medium-salinity soil instead of the high-salinity soil in field conditions. A possible mechanism may be that the relatively high-salinity soil changed the plant nutritional quality or other plant defensive traits. The results from this study may help to identify more appropriate practices to control CBW in Bt cotton fields with different soil salinity levels.

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

    NARCIS (Netherlands)

    Shariatinajafabadi, Mitra; Wang, Tiejun; Skidmore, A.K.; Toxopeus, A.G.; Kölzsch, Andrea; Nolet, Bart; Exo, K-M.; Griffin, L.

    2014-01-01

    Many migrating herbivores rely on plant biomass to fuel their life cycles and have adapted to following changes in plant quality through time. The green wave hypothesis predicts that herbivorous waterfowl will follow the wave of food availability and quality during their spring migration. However,

  18. Avoidance and tolerance to avian herbivores in aquatic plants

    NARCIS (Netherlands)

    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

  19. Metabolomic analysis of the interaction between plants and herbivores

    NARCIS (Netherlands)

    Jansen, J.J.; Allwood, J.W.; Marsden-Edwards, E.; Putten, van der W.H.; Goodacre, R.; Dam, van M.

    2009-01-01

    Insect herbivores by necessity have to deal with a large arsenal of plant defence metabolites. The levels of defence compounds may be increased by insect damage. These induced plant responses may also affect the metabolism and performance of successive insect herbivores. As the chemical nature of

  20. Insect herbivores should follow plants escaping their relatives

    NARCIS (Netherlands)

    Yguel, B.; Bailey, R.I.; Villemant, C.; Brault, A.; Jactel, H.; Prinzing, A.

    2014-01-01

    Neighboring plants within a local community may be separated by many millions of years of evolutionary history, potentially reducing enemy pressure by insect herbivores. However, it is not known how the evolutionary isolation of a plant affects the fitness of an insect herbivore living on such a

  1. Biomass and Abundance of Herbivorous Fishes on Coral Reefs off ...

    African Journals Online (AJOL)

    Benthic cover and fishing intensity appear to influence the biomass of herbivorous fish communities more on the reefs of Andavadoaka, highlighting the importance of Marine Protected Areas to protect both corals and fish. Keywords: Herbivorous fish, biomass, coral cover, algal turf, fishing, Marine Protected Areas.

  2. Seasonality of fibrolytic enzyme activity in herbivore microbial ...

    African Journals Online (AJOL)

    Fibre (cellulose, hemicellulose and lignin) is the most abundant polysaccharide in nature and is hydrolysed by gut micro-organisms of herbivores because they can produce a set of extracellular enzymes. This study examined seasonal changes in the fibrolytic enzyme activity of microbial ecosystems of five herbivores ...

  3. Density Dependence and Growth Rate: Evolutionary Effects on Resistance Development to Bt (Bacillus thuringiensis).

    Science.gov (United States)

    Martinez, Jeannette C; Caprio, Michael A; Friedenberg, Nicholas A

    2018-02-09

    It has long been recognized that pest population dynamics can affect the durability of a pesticide, but dose remains the primary component of insect resistance management (IRM). For transgenic pesticidal traits such as Bt (Bacillus thuringiensis Berliner (Bacillales: Bacillaceae)), dose (measured as the mortality of susceptibles caused by a toxin) is a relatively fixed characteristic and often falls below the standard definition of high dose. Hence, it is important to understand how pest population dynamics modify durability and what targets they present for IRM. We used a deterministic model of a generic arthropod pest to examine how timing and strength of density dependence interacted with population growth rate and Bt mortality to affect time to resistance. As in previous studies, durability typically reached a minimum at intermediate doses. However, high population growth rates could eliminate benefits of high dose. The timing of density dependence had a more subtle effect. If density dependence operated simultaneously with Bt mortality, durability was insensitive to its strengths. However, if density dependence was driven by postselection densities, decreasing its strength could increase durability. The strength of density dependence could affect durability of both single traits and pyramids, but its influence depended on the timing of density dependence and size of the refuge. Our findings suggest the utility of a broader definition of high dose, one that incorporates population-dynamic context. That maximum growth rates and timing and strength of interactions causing density dependent mortality can all affect durability, also highlights the need for ecologically integrated approaches to IRM research. © The Author(s) 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  4. 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…

  5. 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...

  6. Lima bean leaves exposed to herbivore-induced conspecific plant volatiles attract herbivores in addition to carnivores

    NARCIS (Netherlands)

    Horiuchi, J.I.; Arimura, G.I.; Ozawa, R.; Shimoda, T.; Dicke, M.; Takabayashi, J.; Nishioka, T.

    2003-01-01

    We tested the response of the herbivorous mite Tetranychus urticae to uninfested lima bean leaves exposed to herbivore-induced conspecific plant volatiles by using a Y-tube olfactometer. First, we confirmed that exposed uninfested leaves next to infested leaves were more attractive to carnivorous

  7. Herbivore-induced plant volatiles accurately predict history of coexistence, diet breadth, and feeding mode of herbivores.

    NARCIS (Netherlands)

    Danner, H.; Desurmont, G.A.; Cristescu, S.M.; Dam, N.M. van

    2017-01-01

    Herbivore-induced plant volatiles (HIPVs) serve as specific cues to higher trophic levels. Novel, exotic herbivores entering native foodwebs may disrupt the infochemical network as a result of changes in HIPV profiles. Here, we analysed HIPV blends of native Brassica rapa plants infested with one of

  8. Adaptation of a polyphagous herbivore to a novel host plant extensively shapes the transcriptome of herbivore and host

    NARCIS (Netherlands)

    Wybouw, N.; Zhurov, V.; Martel, C.; Bruinsma, K.A.; Hendrickx, F.; Grbić, V.; van Leeuwen, T.

    2015-01-01

    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

  9. Lengthening of insect development on Bt zone results in adult emergence asynchrony: does it influence the effectiveness of the high dose/refuge zone strategy?

    Science.gov (United States)

    Gryspeirt, Aiko; Grégoire, Jean-Claude

    2012-11-15

    The “High Dose/Refuge” strategy (HD/R) is the currently recommended Insect Resistance Management strategy (IRM) to limit resistance development to Bacillus thuringiensis (Bt) plants. This strategy requires planting a “refuge zone” composed of non-Bt plants suitable for the target insect and in close proximity to a “Bt zone” expressing a high toxin concentration. One of the main assumptions is that enough susceptible adults mate with resistant insects. However, previous studies have suggested that the high toxin concentration produced by Bt plants induces slower insect development, creating an asynchrony in emergence between the refuge and the Bt zone and leading to assortative mating between adults inside each zone. Here, we develop a deterministic model to estimate the impact of toxin concentration, emergence asynchrony and refuge zone size on the effectiveness of the HD/R strategy. We conclude that emergence asynchrony only affects resistance when toxin concentration is high and resistance is recessive. Resistance develops more rapidly and survival of susceptible insects is higher at lower toxin concentration, but in such situations, resistance is insensitive to emergence asynchrony.

  10. Visual and Real-Time Event-Specific Loop-Mediated Isothermal Amplification Based Detection Assays for Bt Cotton Events MON531 and MON15985.

    Science.gov (United States)

    Randhawa, Gurinder Jit; Chhabra, Rashmi; Bhoge, Rajesh K; Singh, Monika

    2015-01-01

    Bt cotton events MON531 and MON15985 are authorized for commercial cultivation in more than 18 countries. In India, four Bt cotton events have been commercialized; more than 95% of total area under genetically modified (GM) cotton cultivation comprises events MON531 and MON15985. The present study reports on the development of efficient event-specific visual and real-time loop-mediated isothermal amplification (LAMP) assays for detection and identification of cotton events MON531 and MON15985. Efficiency of LAMP assays was compared with conventional and real-time PCR assays. Real-time LAMP assay was found time-efficient and most sensitive, detecting up to two target copies within 35 min. The developed real-time LAMP assays, when combined with efficient DNA extraction kit/protocol, may facilitate onsite GM detection to check authenticity of Bt cotton seeds.

  11. 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.

  12. Life history traits of Helicoverpa zea (Lepidoptera: Noctuidae) on non-Bt and Bt transgenic corn hybrids in eastern North Carolina.

    Science.gov (United States)

    Storer, N P; Van Duyn, J W; Kennedy, G G

    2001-10-01

    Transgenic varieties of field corn that express the CrylAb B. thuringiensis (Bt) toxin in ear tissue present the potential of reducing ear feeding by the corn earworm, Helicoverpa zea (Lepidoptera: Noctuidae), and for reducing the size of populations of the insect infesting other host crops. Life history parameters of H. zea feeding on ears of conventional and Bt field corn varieties were measured in field plots in eastern North Carolina in 1997 and 1998. Transformation events investigated were Mon-810 and Bt-11. Bt corn was found to cause a steady mortality of larvae during development, but permitted approximately 15-40% survival to the prepupal stage compared with non-Bt corn. Mortality of prepupae and pupae from Bt corn was also higher than from non-Bt corn, reducing overall adult production by 65-95%. The larvae that did survive grew more slowly on Bt than on non-Bt corn, and produced pupae that weighed 33% less. Pupation and adult eclosion were delayed by 6-10 d by feeding on Bt corn ears. Corn varieties expressing Bt in ear tissue have the potential to reduce H. zea ear feeding by up to 80%, and the potential to reduce populations emerging from ear-stage corn fields to infest cotton, soybean and other crops by around 75%. To have a measurable effect on area-wide populations, Bt corn varieties would need to be planted in large proportions of corn fields. Extensive planting of varieties such as those tested here, having only moderate effects on H. zea, would raise concerns about rapid evolution of resistance.

  13. 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

  14. Impact of Bt-cotton on soil microbiological and biochemical attributes

    Directory of Open Access Journals (Sweden)

    Sanaullah Yasin

    2016-10-01

    Full Text Available Transgenic Bt-cotton produces Bt-toxins (Cry proteins which may accumulate and persist in soil due to their binding ability on soil components. In the present study, the potential impacts of Bt- and non-Bt genotypes of cotton on soil microbial activity, substrate use efficiency, viable microbial population counts, and nutrient dynamics were studied. Two transgenic Bt-cotton genotypes (CIM-602 CIM-599 expressing cry1 Ac gene and two non-Bt cotton genotypes (CIM-573 and CIM-591 were used to evaluate their impact on biological and chemical properties of soil across the four locations in Punjab. Field trials were conducted at four locations (Central Cotton Research Institute-Multan, Naseer Pur, Kot Lal Shah, and Cotton Research Station-Bahawalpur of different agro-ecological zones of Punjab. Rhizosphere soil samples were collected by following standard procedure from these selected locations. Results reveled that Bt-cotton had no adverse effect on microbial population (viable counts and enzymatic activity of rhizosphere soil. Bacterial population was more in Bt-cotton rhizosphere than that of non-Bt cotton rhizosphere at all locations. Phosphatase, dehydrogenase, and oxidative metabolism of rhizosphere soil were more in Bt-cotton genotypes compared with non-Bt cotton genotypes. Cation exchange capacity, total nitrogen, extractable phosphorous, extractable potassium, active carbon, Fe and Zn contents were higher in rhizosphere of Bt-cotton genotypes compared with non-Bt cotton genotypes. It can be concluded from present study that the cultivation of Bt-cotton expressing cry1 Ac had apparently no negative effect on metabolic, microbiological activities, and nutrient dynamics of soils. Further work is needed to investigate the potential impacts of Bt-cotton on ecology of soil-dwelling insects and invertebrates before its recommendation for extensive cultivation.

  15. 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

  16. Relevance of Bt toxin interaction studies for environmental risk assessment of genetically modified crops.

    Science.gov (United States)

    De Schrijver, Adinda; De Clercq, Patrick; de Maagd, Ruud A; van Frankenhuyzen, Kees

    2015-12-01

    In recent years, different Bacillus thuringiensis (Bt) toxin-encoding genes have been combined or 'stacked' in genetically modified (GM) crops. Synergism between Bt proteins may occur and thereby increase the impact of the stacked GM event on nontarget invertebrates compared to plants expressing a single Bt gene. On the basis of bioassay data available for Bt toxins alone or in combination, we argue that the current knowledge of Bt protein interactions is of limited relevance in environmental risk assessment (ERA). © 2015 Society for Experimental Biology, Association of Applied Biologists and John Wiley & Sons Ltd.

  17. Multimodal Protein Constructs for Herbivore Insect Control

    Directory of Open Access Journals (Sweden)

    Frank Sainsbury

    2012-06-01

    Full Text Available Transgenic plants expressing combinations of microbial or plant pesticidal proteins represent a promising tool for the efficient, durable control of herbivorous insects. In this review we describe current strategies devised for the heterologous co-expression of pesticidal proteins in planta, some of which have already shown usefulness in plant protection. Emphasis is placed on protein engineering strategies involving the insertion of single DNA constructs within the host plant genome. Multimodal fusion proteins integrating complementary pesticidal functions along a unique polypeptide are first considered, taking into account the structural constraints associated with protein or protein domain grafting to biologically active proteins. Strategies that allow for the co- or post-translational release of two or more pesticidal proteins are then considered, including polyprotein precursors releasing free proteins upon proteolytic cleavage, and multicistronic transcripts for the parallel translation of single protein-encoding mRNA sequences.

  18. Investigating the Value of Section Scores for the "TOEFL iBT"® Test. "TOEFL iBT"® Research Report. TOEFL iBT-21. ETS Research Report RR-13-35

    Science.gov (United States)

    Sawaki, Yasuyo; Sinharay, Sandip

    2013-01-01

    This study investigates the value of reporting the reading, listening, speaking, and writing section scores for the "TOEFL iBT"® test, focusing on 4 related aspects of the psychometric quality of the TOEFL iBT section scores: reliability of the section scores, dimensionality of the test, presence of distinct score profiles, and the…

  19. Discourse Characteristics of Writing and Speaking Task Types on the "TOEFL iBT"® Test: A Lexico-Grammatical Analysis. "TOEFL iBT"® Research Report. TOEFL iBT-19. Research Report. RR-13-04

    Science.gov (United States)

    Biber, Douglas; Gray, Bethany

    2013-01-01

    One of the major innovations of the "TOEFL iBT"® test is the incorporation of integrated tasks complementing the independent tasks to which examinees respond. In addition, examinees must produce discourse in both modes (speech and writing). The validity argument for the TOEFL iBT includes the claim that examinees vary their discourse in…

  20. 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.

  1. Insect resistance to Bt crops: lessons from the first billion acres.

    Science.gov (United States)

    Tabashnik, Bruce E; Brévault, Thierry; Carrière, Yves

    2013-06-01

    Evolution of resistance in pests can reduce the effectiveness of insecticidal proteins from Bacillus thuringiensis (Bt) produced by transgenic crops. We analyzed results of 77 studies from five continents reporting field monitoring data for resistance to Bt crops, empirical evaluation of factors affecting resistance or both. Although most pest populations remained susceptible, reduced efficacy of Bt crops caused by field-evolved resistance has been reported now for some populations of 5 of 13 major pest species examined, compared with resistant populations of only one pest species in 2005. Field outcomes support theoretical predictions that factors delaying resistance include recessive inheritance of resistance, low initial frequency of resistance alleles, abundant refuges of non-Bt host plants and two-toxin Bt crops deployed separately from one-toxin Bt crops. The results imply that proactive evaluation of the inheritance and initial frequency of resistance are useful for predicting the risk of resistance and improving strategies to sustain the effectiveness of Bt crops.

  2. 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

    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

  3. 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

  4. On risk and regulation: Bt crops in India.

    Science.gov (United States)

    Herring, Ronald J

    2014-07-03

    Genetic engineering in agriculture raises contentious politics unknown in other applications of molecular technology. Controversy originated and persists for inter-related reasons; these are not primarily, as frequently assumed, differences over scientific findings, but rather about the relationship of science to 'risk.' First, there are inevitably differences in how to interpret 'risk' in situations in which there are no established findings of specific hazard; 'Knightian uncertainty' defines this condition. Science claims no method of resolution in such cases of uncertainty. Second, science has no claim about risk preferences in a normative sense. In genetic engineering, Knightian uncertainty is pervasive; declaring uncertainty to constitute 'risk' enables a precautionary politics in which no conceivable evidence from science can confirm absence of risk. This is the logic of the precautionary state. The logic of the developmental state is quite different: uncertainty is treated as an inevitable component of change, and therefore a logic of acceptable uncertainty, parallel to acceptable risk of the sort deployed in cost-benefit analysis in other spheres of behavior, dominates policy. India's official position on agricultural biotechnology has been promotional, as expected from a developmental state, but regulation of Bt crops has rested in a section of the state operating more on precautionary than developmental logic. As a result, notwithstanding the developmental success of Bt cotton, Bt brinjal [eggplant, aubergine] encountered a moratorium on deployment despite approval by the regulatory scientific body designated to assess biosafety.

  5. [Arthropod community structures in transgenic Bt cotton fields].

    Science.gov (United States)

    Wei, G; Cui, L; Zhang, X; Liu, S; Lü, N; Zhang, Q

    2001-08-01

    Arthropod community structures were investigated in transgenic Bt cultivars, Bollgard(B) and Chinese cotton 30 (CC30), and common cultivars, control (C) and no control (NC) cotton field in North China in 1998. The results showed that compared with common cultivars, the species richness and the number of total individual of arthropod community in transgenic Bt cultivars field were reduced 2.4-16.3% and 71.0-78.3% respectively, in which dominant species in phytophagous subcommunity varied. The number of individual of predatory and parastic subcommunity were all increased. The similarity coefficient between CC30 and NC was 0.8243, B and NC 0.7320, B and C 0.3380, C and NC 0.3128, CC30 and C 0.2665. The order of diversity and evenness value of these were CC30 (2.3712 and 0.6428), NC (2.3654 and 0.6251), B (2.1364 and 0.5791), and C (1.0877 and 0.2949), their dominant value was 0.8726 (C), 0.3528(B), 0.1178(NC) and 0.1048 (CC30) respectively. It was concluded that different integrated pest management (IPM) strategy should be implemented in transgenic Bt cotton instead of common variety cotton field.

  6. Fine-tuning the 'plant domestication-reduced defense' hypothesis: specialist vs generalist herbivores.

    Science.gov (United States)

    Gaillard, Mickaël D P; Glauser, Gaétan; Robert, Christelle A M; Turlings, Ted C J

    2017-09-06

    Domesticated plants are assumed to have weakened chemical defenses. We argue, however, that artificial selection will have maintained defense traits against specialized herbivores that have coexisted with the crops throughout their domestication. We assessed the performance of eight species of insect herbivores from three feeding guilds on six European maize lines and six populations of their wild ancestor, teosinte. A metabolomics approach was used in an attempt to identify compounds responsible for observed differences in insect performance. Insects consistently performed better on maize than on teosinte. As hypothesized, this difference was greater for generalist herbivores that are normally not found on teosinte. We also found clear differences in defense metabolites among the different genotypes, but none that consistently correlated with differences in performance. Concentrations of benzoxazinoids, the main chemical defense in maize, tended to be higher in leaves of teosinte, but the reverse was true for the roots. It appears that chemical defenses that target specialized insects are still present at higher concentrations in cultivated maize than compounds that are more effective against generalists. These weakened broad-spectrum defenses in crops may explain the successes of novel pests. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  7. Assessing the functional diversity of herbivorous reef fishes using a compound-specific stable isotope approach

    KAUST Repository

    Tietbohl, Matthew

    2016-12-01

    Herbivorous coral reef fishes play an important role in helping to structure their environment directly by consuming algae and indirectly by promoting coral health and growth. These fishes are generally separated into three broad groups: browsers, grazers, and excavators/scrapers, with these groupings often thought to have a fixed general function and all fishes within a group thought to have similar ecological roles. This categorization assumes a high level of functional redundancy within herbivorous fishes. However, recent evidence questions the use of this broad classification scheme, and posits that there may actually be more resource partitioning within these functional groupings. Here, I use a compound-specific stable isotope approach (CSIA) to show there appears to be a greater diversity of functional roles than previously assumed within broad functional groups. The δ13C signatures from essential amino acids of reef end-members (coral, macroalgae, detritus, and phytoplankton) and fish muscle were analyzed to investigate differences in resource use between fishes. Most end-members displayed clear isotopic differences, and most fishes within functional groups were dissimilar in their isotopic signature, implying differences in the resources they target. No grazers closely resembled each other isotopically, implying a much lower level of functional redundancy within this group; scraping parrotfish were also distinct from excavating parrotfish and to a lesser degree distinct between scrapers. This study highlights the potential of CSIA to help distinguish fine-scale ecological differences within other groups of reef organisms as well. These results question the utility of lumping nominally herbivorous fishes into broad groups with assumed similar roles. Given the apparent functional differences between nominally herbivorous reef fishes, it is important for managers to incorporate the diversity of functional roles these fish play.

  8. Feeding Behaviour on Host Plants May Influence Potential Exposure to Bt Maize Pollen of Aglais Urticae Larvae (Lepidoptera, Nymphalidae

    Directory of Open Access Journals (Sweden)

    Andreas Lang

    2015-08-01

    Full Text Available Non-target butterfly larvae may be harmed by feeding on host plants dusted with Bt maize pollen. Feeding patterns of larvae and their utilization of host plants can affect the adverse Bt impact because the maize pollen is distributed unequally on the plant. In a field study, we investigated the feeding of larvae of the Small Tortoiseshell, Aglais urticae, on nettles, Urtica dioica. Young larvae used smaller host plants than older larvae. In general, the position of the larvae was in the top part of the host plant, but older larvae showed a broader vertical distribution on the nettles. Leaf blades and leaf tips were the plant parts most often consumed. Leaf veins were consumed but midribs were fed on to a lesser extent than other plant veins, particularly by young larvae. The feeding behavior of the larvae may increase possible exposure to Bt maize pollen because pollen densities are expected to be higher on the top parts and along leaf veins of nettles.

  9. A New Method for in Situ Measurement of Bt-Maize Pollen Deposition on Host-Plant Leaves

    Directory of Open Access Journals (Sweden)

    Rudolph Vögel

    2011-02-01

    Full Text Available Maize is wind pollinated and produces huge amounts of pollen. In consequence, the Cry toxins expressed in the pollen of Bt maize will be dispersed by wind in the surrounding vegetation leading to exposure of non-target organisms (NTO. NTO like lepidopteran larvae may be affected by the uptake of Bt-pollen deposited on their host plants. Although some information is available to estimate pollen deposition on host plants, recorded data are based on indirect measurements such as shaking or washing off pollen, or removing pollen with adhesive tapes. These methods often lack precision and they do not include the necessary information such as the spatial and temporal variation of pollen deposition on the leaves. Here, we present a new method for recording in situ the amount and the distribution of Bt-maize pollen deposited on host plant leaves. The method is based on the use of a mobile digital microscope (Dino-Lite Pro, including DinoCapture software, which can be used in combination with a notebook in the field. The method was evaluated during experiments in 2008 to 2010. Maize pollen could be correctly identified and pollen deposition as well as the spatial heterogeneity of maize pollen deposition was recorded on maize and different lepidopteran host plants (Centaurea scabiosa, Chenopodium album, Rumex spp., Succina pratensis and Urtica dioica growing adjacent to maize fields.

  10. The impact of common smut(Ustilago maydis) on aflatoxin and fumonisin in transgenic Bt and non-Bt maize (Zea mays)

    Science.gov (United States)

    Corn infected with Ustilago maydis (common smut), produces galls that are valued food in certain cultures, but may be contaminated with mycotoxins. Field studies conducted in Elizabeth, Mississippi used near-isogenic Bt and non-Bt corn hybrids. The levels of aflatoxin and fumonisin were determined ...

  11. 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

  12. [Transformation and expression of specific insecticide gene Bt cry3A in resident endogenetic bacteria isolated from Apriona germari (Hope) larvae intestines].

    Science.gov (United States)

    Zhongkang, Wang; Wei, He; Guoxiong, Peng; Yuxian, Xia; Qiang, Li; Youping, Yin

    2008-09-01

    Transforming the specific insecticidal gene Bt cry3A into the dominant resident endogenetic bacteria in intestines of Apriona germari (Hope) larvae to construct transgenic bacteria that can colonize and express the insecticidal gene Bt cry3A perfectly in intestines of Apriona germari (Hope) larvae. We isolated and identified the dominant resident endogenetic bacteria by traditional methods and molecular method based of 16S rDNA analysis. Two Escherichia coli--Bacillus thuringiensis shuttle plasmid pHT305a and pHT7911 which contained specific insecticidal gene Bt cry3A were transformed into two resident endogenetic bacteria Brevibacillus brevis Ag12 and Bacillus thuringiensis Ag13 isolated from A. germari larvae intestines respectively by electro-transformation. Eighteen species of bacteria have isolated and identified from Apriona germari larvae intestines and two of them (Brevibacillus brevis Ag12 and Bacillus thuringiensis Ag13) were selected as starting bacteria to recieve the Bt cry3A. The 4 transgenic engineering strains Ag12-7911, Ag12-305a, Ag13-7911 and Ag13-305a were obtained successfully and validated by testing the plasmid stability in recombinants, transformants vegetal properties, crystal poisonous protein observation, expressional protein SDS-PAGE. The Bt cry3A gene had been transformed into Brevibacillus brevis and Bacillus thuringiensis. Both bioassay and examination of the engineering strains in intestines after feeding them to larvae showed that all these transformant strains (Brevibacillus brevis Ag12-305a, Bacillus thurigiensis Ag13-305a, Brevibacillus brevis Ag12-7911 and Bacillus thurigiensis Ag13-7911) could colonize and express 65 kDa protoxin in intestines of A. germari larvae and had insecticidal activity. We obtained four transgenic bacteria that can colonize and express the target insecticide gene Bt cry3A in A. germari larvae. They may be developed as a new insecticide.

  13. Phytohormone mediation of interactions between herbivores and plant pathogens

    NARCIS (Netherlands)

    Lazebnik, J.; Frago, E.; Dicke, M.; Loon, van J.J.A.

    2014-01-01

    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

  14. Regulatory considerations surrounding the deployment of Bt-expressing cowpea in Africa: report of the deliberations of an expert panel.

    Science.gov (United States)

    Huesing, Joseph; Romeis, Jörg; Ellstrand, Norman; Raybould, Alan; Hellmich, Richard; Wolt, Jeff; Ehlers, Jeff; Dabiré, Clémentine; Fatokun, Christian; Hokanson, Karen; Ishiyaku, Mohammad F; Margam, Venu; Obokoh, Nompumelelo; Mignouna, Jacob; Nangayo, Francis; Ouedraogo, Jeremy; Pasquet, Rémy; Pittendrigh, Barry; Schaal, Barbara; Stein, Jeff; Tamò, Manuele; Murdock, Larry

    2011-01-01

    Cowpea (Vigna unguiculata spp unguiculata) is adapted to the drier agro-ecological zones of West Africa where it is a major source of dietary protein and widely used as a fodder crop. Improving the productivity of cowpea can enhance food availability and security in West Africa. Insect predation--predominately from the legume pod borer (Maruca vitrata), flower thrips (Megalurothrips sjostedti) and a complex of pod-sucking bugs (e.g., Clavigralla spp)--is a major yield-limiting factor in West African cowpea production. Dramatic increases in yield are shown when M. vitrata is controlled with insecticides. However, availability, costs, and safety considerations limit pesticides as a viable option for boosting cowpea production. Development of Bt-cowpea through genetic modification (GM) to control the legume pod borer is a promising approach to cowpea improvement. Cowpea expressing the lepidopteran-active Cry1Ab protein from Bacillus thuringiensis is being developed as a first generation Bt-cowpea crop for West Africa. Appropriate stewardship of Bt-cowpea to assure its sustainability under West African conditions is critical to its successful development. A first step in this process is an environmental risk assessment to determine the likelihood and magnitude of adverse effects of the Cry1Ab protein on key environmental protection goals in West Africa. Here we describe the results of an expert panel convened in 2009 to develop the problem formulation phase for Bt-cowpea and to address specific issues around gene flow, non-target arthropods, and insect resistance management.

  15. Herbivore-induced blueberry volatiles and intra-plant signaling.

    Science.gov (United States)

    Rodriguez-Saona, Cesar R

    2011-12-18

    Herbivore-induced plant volatiles (HIPVs) are commonly emitted from plants after herbivore attack. These HIPVs are mainly regulated by the defensive plant hormone jasmonic acid (JA) and its volatile derivative methyl jasmonate (MeJA). Over the past 3 decades researchers have documented that HIPVs can repel or attract herbivores, attract the natural enemies of herbivores, and in some cases they can induce or prime plant defenses prior to herbivore attack. In a recent paper, I reported that feeding by gypsy moth caterpillars, exogenous MeJA application, and mechanical damage induce the emissions of volatiles from blueberry plants, albeit differently. In addition, blueberry branches respond to HIPVs emitted from neighboring branches of the same plant by increasing the levels of JA and resistance to herbivores (i.e., direct plant defenses), and by priming volatile emissions (i.e., indirect plant defenses). Similar findings have been reported recently for sagebrush, poplar, and lima beans. Here, I describe a push-pull method for collecting blueberry volatiles induced by herbivore (gypsy moth) feeding, exogenous MeJA application, and mechanical damage. The volatile collection unit consists of a 4 L volatile collection chamber, a 2-piece guillotine, an air delivery system that purifies incoming air, and a vacuum system connected to a trap filled with Super-Q adsorbent to collect volatiles. Volatiles collected in Super-Q traps are eluted with dichloromethane and then separated and quantified using Gas Chromatography (GC). This volatile collection method was used in my study to investigate the volatile response of undamaged branches to exposure to volatiles from herbivore-damaged branches within blueberry plants. These methods are described here. Briefly, undamaged blueberry branches are exposed to HIPVs from neighboring branches within the same plant. Using the same techniques described above, volatiles emitted from branches after exposure to HIPVs are collected and

  16. A seed mixture increases dominance of resistance to Bt cotton in Helicoverpa zea.

    Science.gov (United States)

    Brévault, Thierry; Tabashnik, Bruce E; Carrière, Yves

    2015-05-07

    Widely grown transgenic crops producing insecticidal proteins from Bacillus thuringiensis (Bt) can benefit agriculture, but adaptation by pests threatens their continued success. Refuges of host plants that do not make Bt toxins can promote survival of susceptible insects and delay evolution of resistance, particularly if resistance is inherited as a recessive trait. However, data have been lacking to compare the dominance of resistance when Bt and non-Bt seeds are planted in random mixtures versus separate blocks. Here we report results from greenhouse experiments with transgenic cotton producing Bt toxin Cry1Ac and the bollworm, Helicoverpa zea, showing that the dominance of resistance was significantly higher in a seed mixture relative to a block of Bt cotton. The proportion of larvae on non-Bt cotton plants in the seed mixture was also significantly higher than expected under the null hypothesis of random distribution. In simulations based on observed survival, resistance evolved 2- to 4.5-fold faster in the seed mixture relative to separate blocks of Bt and non-Bt cotton. These findings support previous modelling results indicating that block refuges may be more effective than seed mixtures for delaying resistance in pests with mobile larvae and inherently low susceptibility to the toxins in Bt crops.

  17. Structure and biosynthesis of the BT peptide antibiotic from Brevibacillus texasporus.

    Science.gov (United States)

    Wu, Xiaofeng; Ballard, Johnathan; Jiang, Yi Wei

    2005-12-01

    We isolated a novel gram-positive bacterium, Brevibacillus texasporus, that produces an antibiotic, BT. BT is a group of related peptides that are produced by B. texasporus cells in response to nutrient limitation. We report here purification and determination of the structure of the most abundant BT isomer, BT1583. Amino acid composition and tandem mass spectrometry experiments yielded a partial BT1583 structure. The presence of ornithine and d-form residues in the partial BT1583 structure indicated that the peptide is synthesized by a nonribosomal peptide synthetase (NRPS). The BT NRPS operon was rapidly and accurately identified by using a novel in silico NRPS operon hunting strategy that involved direct shotgun genomic sequencing rather than the unreliable cosmid library hybridization scheme. Sequence analysis of the BT NRPS operon indicated that it encodes a colinear modular NRPS with a strict correlation between the NRPS modules and the amino acid residues in the peptide. The colinear nature of the BT NRPS enabled us to utilize the genomic information to refine the BT1583 peptide sequence to Me(2)-4-methyl-4-[(E)-2-butenyl]-4,N-methyl-threonine-L-dO-I-V-V-dK-V-dL-K-dY-L-V-CH2OH. In addition, we report the discovery of novel NRPS codons (sets of the substrate specificity-conferring residues in NRPS modules) for valine, lysine, ornithine, and tyrosine.

  18. Spatio-Temporal Variation in Landscape Composition May Speed Resistance Evolution of Pests to Bt Crops.

    Science.gov (United States)

    Ives, Anthony R; Paull, Cate; Hulthen, Andrew; Downes, Sharon; Andow, David A; Haygood, Ralph; Zalucki, Myron P; Schellhorn, Nancy A

    2017-01-01

    Transgenic crops that express insecticide genes from Bacillus thuringiensis (Bt) are used worldwide against moth and beetle pests. Because these engineered plants can kill over 95% of susceptible larvae, they can rapidly select for resistance. Here, we use a model for a pyramid two-toxin Bt crop to explore the consequences of spatio-temporal variation in the area of Bt crop and non-Bt refuge habitat. We show that variability over time in the proportion of suitable non-Bt breeding habitat, Q, or in the total area of Bt and suitable non-Bt habitat, K, can increase the overall rate of resistance evolution by causing short-term surges of intense selection. These surges can be exacerbated when temporal variation in Q and/or K cause high larval densities in refuges that increase density-dependent mortality; this will give resistant larvae in Bt fields a relative advantage over susceptible larvae that largely depend on refuges. We address the effects of spatio-temporal variation in a management setting for two bollworm pests of cotton, Helicoverpa armigera and H. punctigera, and field data on landscape crop distributions from Australia. Even a small proportion of Bt fields available to egg-laying females when refuges are sparse may result in high exposure to Bt for just a single generation per year and cause a surge in selection. Therefore, rapid resistance evolution can occur when Bt crops are rare rather than common in the landscape. These results highlight the need to understand spatio-temporal fluctuations in the landscape composition of Bt crops and non-Bt habitats in order to design effective resistance management strategies.

  19. A Novel Small Molecule GDNF Receptor RET Agonist, BT13, Promotes Neurite Growth from Sensory Neurons in Vitro and Attenuates Experimental Neuropathy in the Rat

    Directory of Open Access Journals (Sweden)

    Yulia A. Sidorova

    2017-06-01

    Full Text Available Neuropathic pain caused by nerve damage is a common and severe class of chronic pain. Disease-modifying clinical therapies are needed as current treatments typically provide only symptomatic relief; show varying clinical efficacy; and most have significant adverse effects. One approach is targeting either neurotrophic factors or their receptors that normalize sensory neuron function and stimulate regeneration after nerve damage. Two candidate targets are glial cell line-derived neurotrophic factor (GDNF and artemin (ARTN, as these GDNF family ligands (GFLs show efficacy in animal models of neuropathic pain (Boucher et al., 2000; Gardell et al., 2003; Wang et al., 2008, 2014. As these protein ligands have poor drug-like properties and are expensive to produce for clinical use, we screened 18,400 drug-like compounds to develop small molecules that act similarly to GFLs (GDNF mimetics. This screening identified BT13 as a compound that selectively targeted GFL receptor RET to activate downstream signaling cascades. BT13 was similar to NGF and ARTN in selectively promoting neurite outgrowth from the peptidergic class of adult sensory neurons in culture, but was opposite to ARTN in causing neurite elongation without affecting initiation. When administered after spinal nerve ligation in a rat model of neuropathic pain, 20 and 25 mg/kg of BT13 decreased mechanical hypersensitivity and normalized expression of sensory neuron markers in dorsal root ganglia. In control rats, BT13 had no effect on baseline mechanical or thermal sensitivity, motor coordination, or weight gain. Thus, small molecule BT13 selectively activates RET and offers opportunities for developing novel disease-modifying medications to treat neuropathic pain.

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

    Science.gov (United States)

    Scherber, Christoph; Gladbach, David J; Stevnbak, Karen; Karsten, Rune Juelsborg; Schmidt, Inger Kappel; Michelsen, Anders; Albert, Kristian Rost; Larsen, Klaus Steenberg; Mikkelsen, Teis Nørgaard; Beier, Claus; Christensen, Søren

    2013-06-01

    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 (CO2, warming, drought) in a Danish heathland ecosystem. The experiment was established in 2005 as a full factorial split-plot with 6 blocks × 2 levels of CO2 × 2 levels of warming × 2 levels of drought = 48 plots. In 2008, we exposed 432 larvae (n = 9 per plot) of the heather beetle (Lochmaea 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 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, 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.

  1. Ostrinia nubilalis parasitism and the field abundance of non-target insects in transgenic Bacillus thuringiensis corn (Zea mays).

    Science.gov (United States)

    Bourguet, Denis; Chaufaux, Josette; Micoud, Annie; Delos, Marc; Naibo, Bernard; Bombarde, Fany; Marque, Gilles; Eychenne, Nathalie; Pagliari, Carine

    2002-10-01

    In this study, we evaluated in field trials the effects on non-target species, of transgenic corn producing the Cry1Ab toxin of Bacillus thuringiensis (Bt). In 1998, we collected Ostrinia nubilalis (Hübner) larvae from transgenic Bt corn (Novartis Hybrid 176) and non-Bt corn at four geographical sites. We found a significant variation in parasitism by the tachinids Lydella thompsoni (Herting) and Pseudoperichaeta nigrolineata (Walker) among sites, and more parasitism in non-Bt than in Bt fields. The Bt effect did not vary significantly among fields. In 1999, we performed a field experiment at two sites, comparing the temporal abundance of non-target arthropods in Bt corn (Monsanto Hybrid MON810) and non-Bt corn. The non-target insects studied included the aphids Metopolophium dirhodum (Walker), Rhopalosiphum padi (L.) and Sitobion avenae (F.), the bug Orius insidiosus (Say), the syrphid Syrphus corollae (Meigen), the ladybird Coccinella septempunctata (L.), the lacewing Chrysoperla carnea (Stephens), thrips and hymenopteran parasitoids. For all species but one, the number of individuals varied greatly over the season but did not differ between the types of corn. The only exception was thrips which, at one site, was significantly more abundant in Bt corn than in non-Bt corn. However this difference did not remain significant when we took the multiple tests into account. Implications for pest resistance management, population dynamics and risk assessment are discussed.

  2. Contact chemosensation of phytochemicals by insect herbivores

    Science.gov (United States)

    Burse, Antje

    2017-01-01

    Contact chemosensation, or tasting, is a complex process governed by nonvolatile phytochemicals that tell host-seeking insects whether they should accept or reject a plant. During this process, insect gustatory receptors (GRs) contribute to deciphering a host plant's metabolic code. GRs recognise many different classes of nonvolatile compounds; some GRs are likely to be narrowly tuned and others, broadly tuned. Although primary and/or secondary plant metabolites influence the insect's feeding choice, their decoding by GRs is challenging, because metabolites in planta occur in complex mixtures that have additive or inhibitory effects; in diverse forms composed of structurally unrelated molecules; and at different concentrations depending on the plant species, its tissue and developmental stage. Future studies of the mechanism of insect herbivore GRs will benefit from functional characterisation taking into account the spatio-temporal dynamics and diversity of the plant's metabolome. Metabolic information, in turn, will help to elucidate the impact of single ligands and complex natural mixtures on the insect's feeding choice. PMID:28485430

  3. Evaluation for the retention of reproductive structures by Bt and non ...

    African Journals Online (AJOL)

    The retention of the reproductive structures (bolls) was evaluated at 90,120 and 160 days of maturity in eight Bt and non-Bt hybrids from three Private R&D establishments on three dates of sowings (90,120 and 160 days of maturity) and two spacings of 67.5 x 60 cm and 100 x 30 cm. Ankur group Bt hybrids; 651, 2226 and ...

  4. Measuring the contribution of Bt cotton adoption to India's cotton yields leap:

    OpenAIRE

    Gruere, Guillaume P.; Sun, Yan

    2012-01-01

    While a number of empirical studies have demonstrated the role of Bt cotton adoption in increasing Indian cotton productivity at the farm level, there has been questioning around the overall contribution of Bt cotton to the average cotton yield increase observed these last ten years in India. This study examines the contribution of Bt cotton adoption to long- term average cotton yields in India using a panel data analysis of production variables in nine Indian cotton-producing states from 197...

  5. Enhanced depolarization temperature in 0.90NBT-0.05KBT-0.05BT ceramics induced by BT nanowires

    Science.gov (United States)

    Cao, W. P.; Li, W. L.; Feng, Y.; Xu, D.; Wang, W.; Hou, Y. F.; Zhang, T. D.; Fei, W. D.

    2015-03-01

    The depolarization temperature (Td) of piezoelectric materials is an important figure of merit for their application at elevated temperatures. This study focuses on the effect of BaTiO3 (BT) nanowires on Td and piezoelectric properties of morphotropic-phase-boundary 0.90NBT-0.05KBT-0.05BT ceramics. The results reveal that BaTiO3 nanowires can pin the domain wall, leading to the increase of coercive field (Ec) from 21.06 kV/cm to 34.99 kV/cm. The Td value of 0.90NBT-0.05KBT-0.05BT ceramics can be enhanced approximately 20 °C when using BT nanowires instead of BT solution as the raw material. Meanwhile, at the same polarization conditions, the piezoelectric constant of the ceramic added BT nanowires (172 pC/N) is decreased but still remains a larger value compared with those of other lead-free ceramics. The results imply that the addition of BT nanowires into NBT-KBT is a very effective route to improve Td.

  6. 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

  7. Cost of inbreeding in resistance to herbivores in Datura stramonium.

    Science.gov (United States)

    Bello-Bedoy, Rafael; Núñez-Farfán, Juan

    2010-05-01

    Experiments show that inbred progenies are frequently more damaged by herbivores than outcrossed progenies, suggesting that selfing is costly when herbivores are present and can increase the magnitude of inbreeding depression in survival and reproductive components of fitness. The present study assesses whether inbreeding increases herbivory and estimates the magnitude of inbreeding depression on reproductive components of fitness in the annual plant Datura stramonium. Two experiments were performed under natural conditions of herbivory to assess the effect of inbreeding on plant damage in D. stramonium. In the first experiment, outcrossed progeny was generated using foreign pollen donors, whereas inbred progeny was produced by self-pollination. In both groups, survival, herbivore damage and reproductive components of fitness were measured. In the second experiment, inbred and outcrossed progenies were produced using only local pollen donors, and only damage by herbivores was measured. Despite yearly variation in damage caused by the same specialist herbivores, inbred progeny suffered consistently more damage than outcrossed progeny. There was a significant inbreeding depression for fruit number (delta = 0.3), seed number per fruit (delta = 0.19) and seed number per plant (delta = 0.43). Furthermore, significant genetic variation amongst families in the magnitude of inbreeding depression was observed. The results suggest that the plant's mating system modified the pattern of herbivory by specialist insects in D. stramonium. Inbred plants suffer not only from the genetic cost of low vigour but also from greater damage by herbivores. The mechanism by which inbreeding reduces plant resistance to herbivores remains unknown but is an interesting area for future research.

  8. 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.

  9. Macroevolution of plant defenses against herbivores in the evening primroses.

    Science.gov (United States)

    Johnson, Marc T J; Ives, Anthony R; Ahern, Jeffrey; Salminen, Juha-Pekka

    2014-07-01

    Plant species vary greatly in defenses against herbivores, but existing theory has struggled to explain this variation. Here, we test how phylogenetic relatedness, tradeoffs, trait syndromes, and sexual reproduction affect the macroevolution of defense. To examine the macroevolution of defenses, we studied 26 Oenothera (Onagraceae) species, combining chemistry, comparative phylogenetics and experimental assays of resistance against generalist and specialist herbivores. We detected dozens of phenolic metabolites within leaves, including ellagitannins (ETs), flavonoids, and caffeic acid derivatives (CAs). The concentration and composition of phenolics exhibited low to moderate phylogenetic signal. There were clear negative correlations between multiple traits, supporting the prediction of allocation tradeoffs. There were also positively covarying suites of traits, but these suites did not strongly predict resistance to herbivores and thus did not act as defensive syndromes. By contrast, specific metabolites did correlate with the performance of generalist and specialist herbivores. Finally, that repeated losses of sex in Oenothera was associated with the evolution of increased flavonoid diversity and altered phenolic composition. These results show that secondary chemistry has evolved rapidly during the diversification of Oenothera. This evolution has been marked by allocation tradeoffs between traits, some of which are related to herbivore performance. The repeated loss of sex appears also to have constrained the evolution of plant secondary chemistry, which may help to explain variation in defense among plants. © 2014 The Authors. New Phytologist © 2014 New Phytologist Trust.

  10. Exposure of Unwounded Plants to Chemical Cues Associated with Herbivores Leads to Exposure-Dependent Changes in Subsequent Herbivore Attack

    Science.gov (United States)

    Orrock, John L.

    2013-01-01

    Although chemical predator cues often lead to changes in the anti-predator behavior of animal prey, it is not clear whether non-volatile herbivore kairomones (i.e. incidental chemical cues produced by herbivore movement or metabolism but not produced by an attack) trigger the induction of defense in plants prior to attack. I found that unwounded plants (Brassica nigra) that were regularly exposed to kairomones from snails (mucus and feces produced during movement of Helix aspersa) subsequently experienced reduced rates of attack by snails, unlike unwounded plants that received only one initial early exposure to snail kairomones. A follow-up experiment found that mucus alone did not affect snail feeding on previously harvested B. oleracea leaves, suggesting that changes in herbivory on B. nigra were due to changes in plant quality. The finding that chemicals associated with herbivores leads to changes in palatability of unwounded plants suggests that plants eavesdrop on components of non-volatile kairomones of their snail herbivores. Moreover, this work shows that the nature of plant exposure matters, supporting the conclusion that plants that have not been attacked or wounded nonetheless tailor their use of defenses based on incidental chemical information associated with herbivores and the timing with which cues of potential attack are encountered. PMID:24278210

  11. Exposure of unwounded plants to chemical cues associated with herbivores leads to exposure-dependent changes in subsequent herbivore attack.

    Directory of Open Access Journals (Sweden)

    John L Orrock

    Full Text Available Although chemical predator cues often lead to changes in the anti-predator behavior of animal prey, it is not clear whether non-volatile herbivore kairomones (i.e. incidental chemical cues produced by herbivore movement or metabolism but not produced by an attack trigger the induction of defense in plants prior to attack. I found that unwounded plants (Brassica nigra that were regularly exposed to kairomones from snails (mucus and feces produced during movement of Helix aspersa subsequently experienced reduced rates of attack by snails, unlike unwounded plants that received only one initial early exposure to snail kairomones. A follow-up experiment found that mucus alone did not affect snail feeding on previously harvested B. oleracea leaves, suggesting that changes in herbivory on B. nigra were due to changes in plant quality. The finding that chemicals associated with herbivores leads to changes in palatability of unwounded plants suggests that plants eavesdrop on components of non-volatile kairomones of their snail herbivores. Moreover, this work shows that the nature of plant exposure matters, supporting the conclusion that plants that have not been attacked or wounded nonetheless tailor their use of defenses based on incidental chemical information associated with herbivores and the timing with which cues of potential attack are encountered.

  12. 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.......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 expected from the added impacts of herbivore and pathogen when they attack alone. 2. Previous studies have suggested synergistic and antagonistic impacts on plant performance from certain combinations of arthropods and pathogens, for example, synergistic impacts from necrotrophic pathogens together...

  13. Allometry and spatial scales of foraging in mammalian herbivores.

    Science.gov (United States)

    Laca, Emilio A; Sokolow, Susanne; Galli, Julio R; Cangiano, Carlos A

    2010-03-01

    Herbivores forage in spatially complex habitats. Due to allometry and scale-dependent foraging, herbivores are hypothesized to perceive and respond to heterogeneity of resources at scales relative to their body sizes. This hypothesis has not been manipulatively tested for animals with only moderate differences in body size and similar food niches. We compared short-term spatial foraging behavior of two herbivores (sheep and cattle) with similar dietary niche but differing body size. Although intake rates scaled allometrically with body mass (mass(0.75)), spatial foraging strategies substantially differed, with cattle exhibiting a coarser-grained use of the 'foodscape.' Selectivity by cattle (and not sheep) for their preferred food was more restricted when patches were smaller (< 10 m(2)). We conclude that differences in spatial scales of selection offers a plausible mechanism by which species can coexist on shared resources that exhibit multiple scales of spatial heterogeneity.

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

    DEFF Research Database (Denmark)

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

    2013-01-01

    2, warming, drought) in a Danish heathland ecosystem. The experiment was established in 2005 as a full factorial split-plot with 6 blocks × 2 levels of CO2 × 2 levels of warming × 2 levels of drought = 48 plots. In 2008, we exposed 432 larvae (n = 9 per plot) of the heather beetle (Lochmaea......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...

  15. 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

  16. Do herbivores eavesdrop on ant chemical communication to avoid predation?

    Directory of Open Access Journals (Sweden)

    David J Gonthier

    Full Text Available Strong effects of predator chemical cues on prey are common in aquatic and marine ecosystems, but are thought to be rare in terrestrial systems and specifically for arthropods. For ants, herbivores are hypothesized to eavesdrop on ant chemical communication and thereby avoid predation or confrontation. Here I tested the effect of ant chemical cues on herbivore choice and herbivory. Using Margaridisa sp. flea beetles and leaves from the host tree (Conostegia xalapensis, I performed paired-leaf choice feeding experiments. Coating leaves with crushed ant liquids (Azteca instabilis, exposing leaves to ant patrolling prior to choice tests (A. instabilis and Camponotus textor and comparing leaves from trees with and without A. instabilis nests resulted in more herbivores and herbivory on control (no ant-treatment relative to ant-treatment leaves. In contrast to A. instabilis and C. textor, leaves previously patrolled by Solenopsis geminata had no difference in beetle number and damage compared to control leaves. Altering the time A. instabilis patrolled treatment leaves prior to choice tests (0-, 5-, 30-, 90-, 180-min. revealed treatment effects were only statistically significant after 90- and 180-min. of prior leaf exposure. This study suggests, for two ecologically important and taxonomically diverse genera (Azteca and Camponotus, ant chemical cues have important effects on herbivores and that these effects may be widespread across the ant family. It suggests that the effect of chemical cues on herbivores may only appear after substantial previous ant activity has occurred on plant tissues. Furthermore, it supports the hypothesis that herbivores use ant chemical communication to avoid predation or confrontation with ants.

  17. Cross-pollination of nontransgenic corn ears with transgenic Bt corn: efficacy against lepidopteran pests and implications for resistance management.

    Science.gov (United States)

    Burkness, E C; O'Rourke, P K; Hutchison, W D

    2011-10-01

    The efficacy of nontransgenic sweet corn, Zea mays L., hybrids cross-pollinated by Bacillus thuringiensis (Bt) sweet corn hybrids expressing Cry1Ab toxin was evaluated in both field and laboratory studies in Minnesota in 2000. Non-Bt and Bt hybrids (maternal plants) were cross-pollinated with pollen from both non-Bt and Bt hybrids (paternal plants) to create four crosses. Subsequent crosses were evaluated for efficacy in the field against European corn borer, Ostrinia nubilalis (Hübner), and corn earworm, Helicoverpa zea (Boddie), and in laboratory bioassays against O. nubilalis. Field studies indicated that crosses with maternal Bt plants led to low levels of survival for both O. nubilalis and H. zea compared with the non-Bt x non-Bt cross. However, the cross between non-Bt ears and Bt pollen led to survival rates of 43 and 63% for O. nubilalis and H. zea larvae, respectively. This intermediate level of survival also was reflected in the number of kernels damaged. Laboratory bioassays for O. nubilalis, further confirmed field results with larval survival on kernels from the cross between non-Bt ears and Bt pollen reaching 60% compared with non-Bt crossed with non-Bt. These results suggest that non-Bt refuge plants, when planted in proximity to Bt plants, and cross-pollinated, can result in sublethal exposure of O. nubilalis and H. zea larvae to Bt and may undermine the high-dose/refuge resistance management strategy for corn hybrids expressing Cry1Ab.

  18. screening of new isolates of bt and cloning of their dna amplicons

    African Journals Online (AJOL)

    NEMAPPA

    2012-09-18

    Sep 18, 2012 ... Screening of more number of Bt isolates is relevant for identifying new cry genes from new isolates of Bt. New gene sequences encoding more active toxins could be used for developing better versions of transgenic crop plants. So, the present study was undertaken with the objectives of characterization of ...

  19. Application of Cry1Ab/Ac Bt strip for screening of resistance for ...

    African Journals Online (AJOL)

    ABU ZAYD

    2013-10-02

    Oct 2, 2013 ... segregating cowpea plants and the genetics of the gene was monitored. The Cry1Ab/Ac Bt strip was ... Key words: Bacillus thuriengiensis, Cry1Ab/Ac Bt strips, transgenic cowpea, Maruca vitrata. INTRODUCTION. Cowpea ... opt for cheaper but more toxic alternatives that impact their health (AATF, 2010).

  20. Application of Cry1Ab/Ac Bt strip for screening of resistance for ...

    African Journals Online (AJOL)

    In this study, the efficacy of using Cry1Ab/Ac Bt strip for detecting Maruca resistant transgene in transgenic cowpea was systematically investigated for the first time through field derived progenies. The results show that the Cry1Ab/Ac Bt strip was effective for detecting the presence of the resistant gene in cowpea genome.

  1. Testing public Bt maize events for control of stem borers in the first ...

    African Journals Online (AJOL)

    Transgenic maize (Zea mays L), developed using modified genes from the bacterium Bacillus thuringiensis (Bt), controls stem borers without observable negative effects to humans, livestock or the environment, and is now sown on 134 million hectares globally. Bt maize could contribute to increasing maize production in ...

  2. Relevance of Bt toxin interaction studies for environmental risk assessment of genetically modified crops

    NARCIS (Netherlands)

    Schrijver, De Adinda; Clercq, De Patrick; Maagd, de R.A.; Frankenhuyzen, van Kees

    2015-01-01

    In recent years, different Bacillus thuringiensis (Bt) toxin-encoding genes have been combined or 'stacked' in genetically modified (GM) crops. Synergism between Bt proteins may occur and thereby increase the impact of the stacked GM event on nontarget invertebrates compared to plants expressing

  3. 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…

  4. 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.

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

    NARCIS (Netherlands)

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

    2007-01-01

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

  6. 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

  7. 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,...

  8. 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

  9. Palaeoenvironmental controls on the distribution of Cretaceous herbivorous dinosaurs

    Science.gov (United States)

    Butler, Richard J.; Barrett, Paul M.

    2008-11-01

    Previous attempts to determine palaeoenvironmental preferences in dinosaurs have generally been qualitative assessments based upon data from restricted geographical areas. Here, we use a global database of Cretaceous herbivorous dinosaurs to identify significant associations between clades and broad palaeoenvironmental categories (‘terrestrial’, ‘coastal’, ‘marine’). Nodosaurid ankylosaurs and hadrosaurids show significant positive associations with marine sediments, while marginocephalians (Ceratopsia, Pachycephalosauria), saurischians (herbivorous theropods, Sauropoda) and ankylosaurid ankylosaurs are significantly positively associated with terrestrial sediments. These results provide quantitative support for the hypothesis that some clades (Nodosauridae, Hadrosauridae) were more abundant in coastal and/or fluvial environments, while others (e.g. Marginocephalia, Ankylosauridae) preferentially inhabited more distal environments.

  10. 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.

  11. Survival and Development of Spodoptera frugiperda and Chrysodeixis includens (Lepidoptera: Noctuidae) on Bt Cotton and Implications for Resistance Management Strategies in Brazil.

    Science.gov (United States)

    Sorgatto, Rodrigo J; Bernardi, Oderlei; Omoto, Celso

    2015-02-01

    In Brazil, Spodoptera frugiperda (J. E. Smith) and Chrysodeixis includens (Walker) are important cotton pests and target of control of Bollgard II (Cry1Ac/Cry2Ab2) and WideStrike (Cry1Ac/Cry1F) cotton technologies. To subsidize an insect resistance management program, we conducted laboratory studies to evaluate the toxicity of these Bt cotton plants throughout larval development of S. frugiperda and C. includens. In bioassays with leaf disc, the efficacy of both Bt cotton plants against neonates was >80% for S. frugiperda and 100% for C. includens. However, S. frugiperda larvae that survived on Bt cotton had >76% of growth inhibition and stunting. In bioassays with S. frugiperda and C. includens larvae fed on non-Bt near-isoline during different time period (from 3 to 18 d) and then transferred to Bollgard II or WideStrike leaves showed that larval susceptibility decreased as larval age increased. For Bollgard II cotton, in all S. frugiperda instars, there were larvae that reached the pupal and adult stages. In contrast, on WideStrike cotton, a few larvae in fifth and sixth instar completed the biological cycle. For C. includens, some larvae in sixth instar originated adults in both Bt cotton plants. In conclusion, Bollgard II and WideStrike cotton technologies showed high efficacy against neonates of S. frugiperda and C. includens. However, the mortality of these species decreases as larval age increase, allowing insect survival in a possible seed mixture environment and favoring the resistance evolution. © The Author 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  12. Evolution of Specialization and Ecological Character Displacement of Herbivores along a Gradient of Plant Quality

    OpenAIRE

    Egas, M.; Sabelis, M W; Dieckmann, U.

    2005-01-01

    We study the combined evolutionary dynamics of herbivore specialization and ecological character displacement, taking into account foraging behavior of the herbivores, and a quality gradient of plant types. Herbivores can adapt by changing two adaptive traits: their level of specialization in feeding efficiency and their point of maximum feeding efficiency along the plant gradient. The number of herbivore phenotypes, their levels of specialization, and the amount of character displacement amo...

  13. 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

  14. Large herbivores as a driving force of woodland-grassland cycles

    NARCIS (Netherlands)

    Cornelissen, Perry

    2017-01-01

    This thesis examines the mutual interactions between the population dynamics of large herbivores and wood-pasture cycles in eutrophic wetlands. Therefore, habitat use and population dynamics of large herbivores, the effects of large herbivores on vegetation development, and the mutual interactions

  15. Large herbivores that strive mightily but eat and drink as friends

    NARCIS (Netherlands)

    Boer, de W.F.; Prins, H.H.T.

    1990-01-01

    Grazing in patches of Cynodon dactylon and of Sporobolus spicatus by four large herbivores, and the interaction between these sedentary herbivores was studied in Lake Manyara National Park, northern Tanzania. The herbivores were the African buffalo, Syncerus caffer; the African elephan, Loxodonta

  16. Does the aboveground herbivore assemblage influence soil bacterial community composition and richness in subalpine grasslands?

    Science.gov (United States)

    Melanie Hodel; Martin Schütz; Martijn L. Vandegehuchte; Beat Frey; Matthias Albrecht; Matt D. Busse; Anita C. Risch

    2014-01-01

    Grassland ecosystems support large communities of aboveground herbivores that can alter ecosystem processes. Thus, grazing by herbivores can directly and indirectly affect belowground properties such as the microbial community structure and diversity. Even though multiple species of functionally different herbivores coexist in grassland ecosystems, most studies have...

  17. Impact of different-sized herbivores on recruiment opportunities for subordinate herbs in grasslands

    NARCIS (Netherlands)

    Bakker, E.S.; Olff, H.

    2003-01-01

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

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

    NARCIS (Netherlands)

    Bakker, Elisabeth S.; Olff, Han

    2003-01-01

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

  19. An ecogenomic analysis of herbivore-induced plant volatiles in Brassica juncea

    NARCIS (Netherlands)

    Mathur, V.; Tytgat, T.O.G.; Hordijk, C.A.; Harhangi, H.R.; Jansen, J.J.; Reddy, A.S.; Harvey, J.A.; Vet, L.E.M.; Dam, van N.M.

    2013-01-01

    Upon herbivore feeding, plants emit complex bouquets of induced volatiles that may repel insect herbivores as well as attract parasitoids or predators. Due to differences in the temporal dynamics of individual components, the composition of the herbivore-induced plant volatile (HIPV) blend changes

  20. Risk assessment and ecological effects of transgenic Bacillus thuringiensis crops on non-target organisms.

    Science.gov (United States)

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

    2011-07-01

    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. © 2011 Institute of Botany, Chinese Academy of Sciences.

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

    Science.gov (United States)

    Haack, Søren; Pedersen, Erik Morre; Jespersen, Sune N; Kallehauge, Jesper F; Lindegaard, Jacob Christian; Tanderup, Kari

    2010-10-01

    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 (GTV(BT)), 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. 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/mm(2)). 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 (ADC(low)) were defined based on an ADC threshold of 1.2 × 10(-3) mm(2)/s, and overlap with target volumes was evaluated. Change of ADC level in target volumes and change of ADC(low) volume from BT1 to BT2 was also evaluated. The mean ADC was significantly lower in GTV(BT) 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 ADC(low) 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 GTV(BT) contained 37.2% volume of low diffusion, HR-CTV 20.3% and IR-CTV 10.8%. 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 different characteristics, with the tumour (GTV(BT

  2. Nitrogen transfer between herbivores and their forage species

    NARCIS (Netherlands)

    Sjögersten, S.; Kuijper, D.; Van der Wal, R.; Loonen, M.J.J.E.; Huiskes, A.H.L.; Woodin, S.J.

    2010-01-01

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

  3. Role of plant peroxisomes in protection against herbivores.

    Science.gov (United States)

    Shabab, Mohammed

    2013-01-01

    Peroxisomes are subcellular organelles of vital importance. They are ubiquitous, have a single membrane and execute numerous metabolic reactions in plants. Plant peroxisomes are multifaceted and have diverse functions including, but not limited to, photomorphogenesis, lipid metabolism, photorespiration, nitrogen metabolism, detoxification and plant biotic interactions. Plants have evolved a variety of defence barriers against herbivory. These barriers are unique and loaded with various metabolites. Peroxisomes play an important role in cells, maintaining the compartmentation of certain specific reactions. They serve as a first line of defence, as peroxisomes generate primary signals such as reactive oxygen species (ROS) and reactive nitrogen species (RNS). Both ROS and RNS sense the invasion by herbivores and dramatically reshape the plant transcriptomes, proteomes, and metabolomes, so indicating the importance of signals generated by peroxisomes. Peroxisomes also store a plethora of important enzymes, which have a key role in producing defence molecules. Some of the main enzymes in the biosynthesis of isoprenoids are present in peroxisomes. These enzymes generate plant volatiles, which have numerous functions and important roles in plant-herbivore communication.Although disputed, the enzyme myrosinase has also been reported to be present in peroxisomes, and myrosinases are well known for their role in the mustard bomb, a powerful defence against herbivores. This chapter focuses on the diverse roles of peroxisomes in the generation of direct and indirect defenses against herbivores.

  4. Modeling herbivorous animal digestive system as 3- continuous ...

    African Journals Online (AJOL)

    Administrator

    2010-12-27

    Dec 27, 2010 ... Herbivores contain microflora in their guts which digest lignocellulosics in their stomachs and intestines by secreting the essential enzymes that perform the function so efficiently that the guts of these animals have been described as the best fermentation tanks known. Hippopotamus amphibious,.

  5. Geographical distribution of the selenium status of herbivores in ...

    African Journals Online (AJOL)

    Unknown

    Abstract. Available information on the selenium (Se) status of grazing herbivores in South Africa is reviewed and collated in the form of a geographical distribution map. Marginal to acute Se deficiencies have been reported to occur in the Midlands region and in mountainous areas of the KwaZulu-Natal province and in the.

  6. Biomass and Abundance of Herbivorous Fishes on Coral Reefs off ...

    African Journals Online (AJOL)

    its effects on coral reef algal communities. Ecological Monographs 56: 345-363. Carpenter RC (1990) Mass mortality of. Diadema antillarum. I Long-term effects on sea urchin population-dynamics and coral reef algal communities. Marine. Biology 104: 67-77. Choat JH (1991) The biology of herbivorous fishes on coral reefs.

  7. 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.

  8. Modeling herbivorous animal digestive system as 3- continuous ...

    African Journals Online (AJOL)

    Modeling herbivorous animal digestive system as 3- continuous stirred tank reactor (CSTR) and 1-plug flow reactor (PFR) in series with specific reference to ... This shows the efficiency of each reactor at converting the purely lignocellulosics substrates to useful products like protein, vitamin, fatty acid and the bye-products.

  9. Strategies to mitigate nitrous oxide emissions from herbivore production systems

    DEFF Research Database (Denmark)

    Schils, R L M; Eriksen, Jørgen; Ledgard, S F

    2013-01-01

    Herbivores are a significant source of nitrous oxide (N2O) emissions. They account for a large share of manure-related N2O emissions, as well as soil-related N2O emissions through the use of grazing land, and land for feed and forage production. It is widely acknowledged that mitigation measures...

  10. The relation between herbivore density and relative resource ...

    African Journals Online (AJOL)

    The relation between the relative density of resources and herbivore density is illustrated by regressions of the ecological density of kudu (Tragelaphus strepsiceros) on the relative density of habitat patches within landscapes for a semi-arid savanna. Habitat suitability models were used to isolate patches of suitable kudu ...

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

    NARCIS (Netherlands)

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

    2000-01-01

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

  12. Geographical distribution of the selenium status of herbivores in ...

    African Journals Online (AJOL)

    Available information on the selenium (Se) status of grazing herbivores in South Africa is reviewed and collated in the form of a geographical distribution map. Marginal to acute Se deficiencies have been reported to occur in the Midlands region and in mountainous areas of the KwaZulu-Natal province and in the southern ...

  13. The Ellis paradigm — humans, herbivores and rangeland systems ...

    African Journals Online (AJOL)

    The scientific and conceptual contributions Jim Ellis made throughout the course of his career reveal a logical progression towards increased understanding of pastoral ecosystems worldwide. Research in wildlife, large herbivores, systems ecology and energy flows through grazing ecosystems formed the basis of his ...

  14. Multi-species wild herbivore systems vs. domestic single species ...

    African Journals Online (AJOL)

    Multi-species wild herbivore systems vs. domestic single species systems: a comparison of net animal productivity. PS Goodman. Abstract. Reports the results of a study conducted to compare the short and medium term net annual harvested animal production for six areas situated in the semi-arid bushveld of north eastern ...

  15. Experimental evidence for herbivore limitation of the treeline.

    Science.gov (United States)

    Speed, James D M; Austrheim, Gunnar; Hester, Alison J; Mysterud, Atle

    2010-11-01

    The treeline ecotone divides forest from open alpine or arctic vegetation states. Treelines are generally perceived to be temperature limited. The role of herbivores in limiting the treeline is more controversial, as experimental evidence from relevant large scales is lacking. Here we quantify the impact of different experimentally controlled herbivore densities on the recruitment and survival of birch Betula pubescens tortuosa along an altitudinal gradient in the mountains of southern Norway. After eight years of summer grazing in large-scale enclosures at densities of 0, 25, and 80 sheep/km2, birch recruited within the whole altitudinal range of ungrazed enclosures, but recruitment was rarer in enclosures with low-density sheep and was largely limited to within the treeline in enclosures with high-density sheep. In contrast, the distribution of saplings (birch older than the experiment) did not differ between grazing treatments, suggesting that grazing sheep primarily limit the establishment of new tree recruits rather than decrease the survival of existing individuals. This study provides direct experimental evidence that herbivores can limit the treeline below its potential at the landscape scale and even at low herbivore densities in this climatic zone. Land use changes should thus be considered in addition to climatic changes as potential drivers of ecotone shifts.

  16. The relation between herbivore density and relative resource ...

    African Journals Online (AJOL)

    Ecological theory can help range scientists to understand the determinants of ecological animal density or, in range management terms, 'carrying capacity'. The relation between the relative density of resources and herbivore density is illustrated by regressions of the ecological density of kudu (Tragelaphus strepsiceros) on ...

  17. Nitrogen transfer between herbivores and their forage species

    NARCIS (Netherlands)

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

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

  18. Error management in plant allocation to herbivore defense.

    Science.gov (United States)

    Orrock, John L; Sih, Andy; Ferrari, Maud C O; Karban, Richard; Preisser, Evan L; Sheriff, Michael J; Thaler, Jennifer S

    2015-08-01

    Herbivores can greatly reduce plant fitness. Error management theory (EMT) predicts the evolution of adaptive plant defensive strategies that err towards making less-costly errors so as to avoid making rare, costly errors. EMT provides a common framework for understanding observed levels of variation in plant defense among and within species. Copyright © 2015 Elsevier Ltd. All rights reserved.

  19. 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

  20. Estimation of grazing by herbivores from analysis of dung | Mabinya ...

    African Journals Online (AJOL)

    The two acids can also be recovered from the dung of various herbivores and their presence can be used as evidence of grazing by animals such as cattle, hippopotamus and warthogs. The reduced presence of these compounds in the dung of goats supports the fact that goats both graze and browse. Analysis of the dung ...

  1. Local adaptation in oviposition choice of a specialist herbivore

    NARCIS (Netherlands)

    Wei, Xianqin; Vrieling, Klaas; Mulder, Patrick P.J.; Klinkhamer, Peter G.L.

    2017-01-01

    Specialist herbivores feed on a restricted number of related plant species and may suffer food shortage if overexploitation leads to periodic defoliation of their food plants. The density, size and quality of food plants are important factors that determine the host plant choice of specialist

  2. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Ilja Sonnemann

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

  4. Herbivores modify the carbon cycle in a warming arctic

    Science.gov (United States)

    Cahoon, S. M.; Sullivan, P.; Welker, J. M.; Post, E.

    2009-12-01

    Typically, our studies of arctic terrestrial ecosystem responses to changes in climate focus on abiotic drivers (i.e. warming or added rain or added snow) and subsequent biogeochemical cycles and plant physiological performance. However, many arctic systems, such as those in western Greenland, are home ranges for large herbivores such as muskoxen and caribou. In order to fully understand how tundra landscapes in Greenland will respond to change, experiments are needed that allow us to quantify whether abiotic (climate warming) and or biotic (presence or absence of herbivores) drivers or their combinations regulate ecosystem function and structure. Here we present the results of two consecutive field seasons in western Greenland in which we quantified the interactive effects of local herbivore foraging and simulated climate warming on ecosystem C and N cycling and leaf level physiology. Large exclosure fences were erected in 2002, and ITEX passive warming chambers were established in 2003 within and adjacent to the fences. We performed weekly CO2 flux measurements during the 2008 and 2009 growing seasons which we normalized to a common irradiance by generating light-response curves at all plots (n=9). Although we observed interannual variability in soil moisture and average daily air temperature, browsing by herbivores was a key factor in the seasonal carbon dynamics. By physically removing leaves and upper stems, caribou and muskoxen altered the community composition, reduced leaf area and in turn decreased gross ecosystem photosynthesis (GEP), regardless of the warming treatment. Neither herbivory nor warming significantly affected ecosystem respiration rates. Thus the reduction in net ecosystem exchange (NEE) was primarily driven by reductions in GEP associated with leaf area removal by grazers. Our results indicate that the biotic influence from large herbivores can significantly influence carbon-derived climatic feedbacks and can no longer be overlooked in

  5. ASSESSING OF HERBIVOROUS AND BENEFICIAL INSECTS ON SWITCHGRASS IN UKRAINE.

    Science.gov (United States)

    Stefanovska, T; Kucherovska, S; Pisdlisnyuk, V

    2014-01-01

    A perennial switchgrass, (Panicum virgatum L.), (C4) that is native to North America has good potential for biomass production because of its wide geographic distribution and adaptability to diverse environmental conditions. Insects can significantly impact the yield and quality of biofuel crops. If switchgrass are to be grown on marginally arable land or in monoculture, it are likely to be plagued with herbivore pests and plant diseases at a rate that exceeds what would be expected if the plants were not stressed in this manner. This biofuel crop has been under evaluation for commercial growing in Ukraine for eight years. However, insect diversity and the potential impact of pests on biomass production of this feedstock have not been accessed yet. The objective of our study, started in 2011, is a survey of switch grass insects by trophic groups and determine species that have pest status at two sites in the Central part of Ukraine (Kiev and Poltava regions). In Poltava site we investigated the effect of nine varieties of switchgrass (lowland and upland) to insects' diversity. We assessed changes over time in the densities of major insects' trophic groups, identifying potential pests and natural enemies. Obtained results indicates that different life stages of herbivorous insects from Hymenoptera, Homoptera, Diptera and Coleoptera orders were present on switchgrass during the growing season. Our study results suggests that choice of variety has an impact on trophic groups' structure and number of insects from different orders on swicthgrass. Herbivores and beneficial insects were the only groups that showed significant differences across sampling dates. The highest population of herbivores insects we recorded on 'Alamo' variety for studied years, although herbivore diversity tended to increase on 'Shelter', 'Alamo' and 'Cave-in-Rock' during 2012 and 2013. 'Dacotah', 'Nebraska', 'Sunburst', 'Forestburg' and 'Carthage' showed the highest level of beneficial insects

  6. GM trees with increased resistance to herbivores: trait efficiency and their potential to promote tree growth

    Directory of Open Access Journals (Sweden)

    Joakim eHjältén

    2015-05-01

    Full Text Available Climate change, as well as a more intensive forestry, is expected to increase the risk of damage by pests and pathogens on trees, which can already be a severe problem in tree plantations. Recent development of biotechnology theoretically allows for resistance enhancement that could help reduce these risks but we still lack a comprehensive understanding of benefits and tradeoffs with pest resistant GM (genetically modified trees. We synthesized the current knowledge on the effectiveness of GM forest trees with increased resistance to herbivores. There is ample evidence that induction of exogenous Bacillus thuringiensis genes reduce performance of target pests whereas upregulation of endogenous resistance traits e.g. phenolics, generates variable results. Our review identified very few studies estimating the realized benefits in tree growth of GM trees in the field. This is concerning as the realized benefit with insect resistant GM plants seems to be context-dependent and likely manifested only if herbivore pressure is sufficiently high. Future studies of secondary pest species and resistance evolution in pest to GM trees should be prioritized. But most importantly we need more long-term field tests to evaluate the benefits and risks with pest resistant GM trees.

  7. GM trees with increased resistance to herbivores: trait efficiency and their potential to promote tree growth.

    Science.gov (United States)

    Hjältén, Joakim; Axelsson, E Petter

    2015-01-01

    Climate change, as well as a more intensive forestry, is expected to increase the risk of damage by pests and pathogens on trees, which can already be a severe problem in tree plantations. Recent development of biotechnology theoretically allows for resistance enhancement that could help reduce these risks but we still lack a comprehensive understanding of benefits and tradeoffs with pest resistant GM (genetically modified) trees. We synthesized the current knowledge on the effectiveness of GM forest trees with increased resistance to herbivores. There is ample evidence that induction of exogenous Bacillus thuringiensis genes reduce performance of target pests whereas upregulation of endogenous resistance traits e.g., phenolics, generates variable results. Our review identified very few studies estimating the realized benefits in tree growth of GM trees in the field. This is concerning as the realized benefit with insect resistant GM plants seems to be context-dependent and likely manifested only if herbivore pressure is sufficiently high. Future studies of secondary pest species and resistance evolution in pest to GM trees should be prioritized. But most importantly we need more long-term field tests to evaluate the benefits and risks with pest resistant GM trees.

  8. Multi Stakeholders' Attitudes toward Bt rice in Southwest, Iran: Application of TPB and Multi Attribute Models.

    Science.gov (United States)

    Ghoochani, Omid M; Ghanian, Mansour; Baradaran, Masoud; Azadi, Hossein

    2017-03-01

    Organisms that have been genetically engineered and modified (GM) are referred to as genetically modified organisms (GMOs). Bt crops are plants that have been genetically modified to produce certain proteins from the soil bacteria Bacillus thuringiensis (Bt), which makes these plants resistant to certain lepidopteran and coleopteran species. Genetically Modified (GM) rice was produced in 2006 by Iranian researchers from Tarom Mowla'ii and has since been called 'Bt rice'. As rice is an important source of food for over 3 billion inhabitants on Earth, this study aims to use a correlational survey in order to shed light on the predicting factors relating to the extent of stakeholders' behavioral intentions towards Bt rice. It is assumed and the results confirm that "attitudes toward GM crops" can be used as a bridge in the Attitude Model and the Behavioral Intention Model in order to establish an integrated model. To this end, a case study was made of the Southwest part of Iran in order to verify this research model. This study also revealed that as a part of the integrated research framework in the Behavior Intention Model both constructs of attitude and the subjective norm of the respondents serve as the predicting factors of stakeholders' intentions of working with Bt rice. In addition, the Attitude Model, as the other part of the integrated research framework, showed that the stakeholders' attitudes toward Bt rice can only be determined by the perceived benefits (e.g. positive outcomes) of Bt rice.

  9. New Coll–HA/BT composite materials for hard tissue engineering

    Energy Technology Data Exchange (ETDEWEB)

    Zanfir, Andrei Vlad [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Material Science, “Politehnica” University of Bucharest, 1-7 Gh. Polizu Street, RO-011061 Bucharest (Romania); Voicu, Georgeta, E-mail: getav2001@yahoo.co.uk [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Material Science, “Politehnica” University of Bucharest, 1-7 Gh. Polizu Street, RO-011061 Bucharest (Romania); Busuioc, Cristina; Jinga, Sorin Ion [Department of Science and Engineering of Oxide Materials and Nanomaterials, Faculty of Applied Chemistry and Material Science, “Politehnica” University of Bucharest, 1-7 Gh. Polizu Street, RO-011061 Bucharest (Romania); Albu, Madalina Georgiana [Department of Collagen, Branch of Leather and Footwear Research, National Institute of Research and Development for Textile and Leather, 93 I. Minulescu Street, RO-031215 Bucharest (Romania); Iordache, Florin [Department of Fetal and Adult Stem Cell Therapy, “Nicolae Simionescu” Institute of Cellular Biology and Pathology of Romanian Academy, 8 B.P. Hasdeu Street, RO-050568 Bucharest (Romania)

    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 35 nm 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. - Highlights: • Collagen–hydroxyapatite/barium titanate composite materials were synthesized. • Barium titanate was produced by combining the sol–gel and hydrothermal methods. • The in vitro tests highlight excellent osteoinductive properties for all samples.

  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 35 nm 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. Copyright © 2016 Elsevier B.V. All rights reserved.

  11. Managing fall armyworm, Spodoptera frugiperda (Lepidoptera: Noctuidae), with Bt maize and insecticides in southern Brazil.

    Science.gov (United States)

    Burtet, Leonardo M; Bernardi, Oderlei; Melo, Adriano A; Pes, Maiquel P; Strahl, Thiago T; Guedes, Jerson Vc

    2017-12-01

    Maize plants expressing insecticidal proteins of Bacillus thuringiensis are valuable options for managing fall armyworm (FAW), Spodoptera frugiperda, in Brazil. However, control failures were reported, and therefore insecticides have been used to control this species. Based on these, we evaluated the use of Bt maize and its integration with insecticides against FAW in southern Brazil. Early-planted Agrisure TL, Herculex, Optimum Intrasect and non-Bt maize plants were severely damaged by FAW and required up to three insecticidal sprays. In contrast, YieldGard VT Pro, YieldGard VT Pro 3, PowerCore, Agrisure Viptera and Agrisure Viptera 3 showed little damage and did not require insecticides. Late-planted Bt maize plants showed significant damage by FAW and required up to four sprays, with the exceptions of Agrisure Viptera and Agrisure Viptera 3. Exalt (first and second sprays); Lannate + Premio (first spray) and Avatar (second spray); and Karate + Match (first spray) and Ampligo (second spray) were the most effective insecticides against FAW larvae in Bt and non-Bt maize. Maize plants expressing Cry proteins exhibited FAW control failures in southern Brazil, necessitating insecticidal sprays. In contrast, Bt maize containing the Vip3Aa20 protein remained effective against FAW. However, regardless of the insecticide used against FAW surviving on Bt maize, grain yields were similar. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

  12. 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.

  13. 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.

  14. Loading and Light Degradation Characteristics of Bt Toxin on Nanogoethite: A Potential Material for Controlling the Environmental Risk of Bt Toxin

    Directory of Open Access Journals (Sweden)

    Xueyong Zhou

    2015-01-01

    Full Text Available Transgenic Bt-modified crops release toxins into soil through root exudates and upon decomposition of residues. The fate of these toxins in soil has not been yet clearly elucidated. Nanogoethite was found to have a different influence on the lifetime and insecticidal activity of Bt toxin. The aim of this study was to elucidate the adsorption characteristics of Bt toxin on nanogoethite and its activity changes before and after adsorption. The adsorption of toxin on nanogoethite reached equilibrium within 5 h, and the adsorption isotherm of Bt toxin on nanogoethite conformed to the Langmuir equation (R2>0.9690. In the range of pH from 6.0 to 8.0, larger adsorption occurred at lower pH value. The toxin adsorption decreased with the temperature between 10 and 50°C. The results of FTIR, XRD, and SEM indicated that toxin did not influence the structure of nanogoethite and the adsorption of toxin only on the surface of nanogoethite. The LC50 value for bound toxin was higher than that of free toxin, and the nanogoethite greatly accelerated the degradation of toxin by ultraviolet irradiation. The above results suggested that nanogoethite is a potential material for controlling the environmental risk of toxin released by Bt transgenic plants.

  15. Biochemical and Molecular Characterization of Barley Plastidial ADP-Glucose Transporter (HvBT1)

    OpenAIRE

    Atta Soliman; Ayele, Belay T.; Fouad Daayf

    2014-01-01

    In cereals, ADP-glucose transporter protein plays an important role in starch biosynthesis. It acts as a main gate for the transport of ADP-glucose, the main precursor for starch biosynthesis during grain filling, from the cytosol into the amyloplasts of endospermic cells. In this study, we have shed some light on the molecular and biochemical characteristics of barley plastidial ADP-glucose transporter, HvBT1. Phylogenetic analysis of several BT1 homologues revealed that BT1 homologues are d...

  16. A Comparative Analysis of Production and Marketing of Bt Cotton and Hybrid Cotton in Saurashtra Region of Gujarat State

    OpenAIRE

    Visawadia, H.R.; Fadadu, A.M.; Tarpara, V.D.

    2006-01-01

    The study has revealed that the total cost per hectare is higher in Bt cotton than hybrid cotton. The cost of seeds has been found higher in Bt cotton, whereas hybrid cotton growers incur more cost on insecticides/ pesticides. This shows the effectiveness of the new technology (Bt cotton) for insect resistance. The average total cost of production as well as the bulk line cost have been found lower in Bt cotton. This depicts a reduction in the unit cost of Bt cotton, which is the distinct adv...

  17. Uptake and transfer of a Bt toxin by a Lepidoptera to its eggs and effects on its offspring.

    Science.gov (United States)

    Paula, Débora Pires; Andow, David A; Timbó, Renata Velozo; Sujii, Edison R; Pires, Carmen S S; Fontes, Eliana M G

    2014-01-01

    Research on non-target effects of transgenic crop plants has focused primarily on bitrophic, tritrophic and indirect effects of entomotoxins from Bacillus thuringiensis, but little work has considered intergenerational transfer of Cry proteins. This work reports a lepidopteran (Chlosyne lacinia) taking up a Bt entomotoxin when exposed to sublethal or low concentrations, transferring the entomotoxin to eggs, and having adverse effects on the first filial generation (F1) offspring. Two bioassays were conducted using a sublethal concentration of toxin (100.0 ng/µl Cry1Ac) for adults and a concentration equal to the LC10 (2.0 ng/µl Cry1Ac) for larvae. Cry1Ac is the most common entomotoxin expressed in Bt cotton in Brazil. In the adult diet bioassay there was no adverse effect on the parental generation (P0) adults, but the F1 larvae had higher mortality and longer development time compared to F1 larvae of parents that did not ingest Cry1Ac. For the 3rd instar larvae, there was no measurable effect on the P0 larvae, pupae and adults, but the F1 larvae had higher mortality and longer development time. Using chemiluminescent Western Blot, Cry1Ac was detected in F1 eggs laid by P0 butterflies from both bioassays. Our study indicates that, at least for this species and these experimental conditions, a ∼65 kDa insecticidal protein can be taken up and transferred to descendants where it can increase mortality and development time.

  18. 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.

  19. 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....... There was a weak significant reduction by 30% on the reproduction of F. fimetaria fed Bt corn in Petri dishes for 21 days. Likewise there was a weak significant reduction by 40% of the reproduction of H. aculeifer by Bt corn in amounts corresponding to 20 g plant material kg-1 soil in the two species soil......-litter microcosm systems. There were no effects of Bt corn materials on the reproduction of F. fimetaria and E. crypticus in the single species soil-litter microcosms. No effects of Bt corn materials on mortality of all the 4 species were observed in all treatments. The tendency of effects of the Bt corn...

  20. Direct transcriptional activation of BT genes by NLP transcription factors is a key component of the nitrate response in Arabidopsis.

    Science.gov (United States)

    Sato, Takeo; Maekawa, Shugo; Konishi, Mineko; Yoshioka, Nozomi; Sasaki, Yuki; Maeda, Haruna; Ishida, Tetsuya; Kato, Yuki; Yamaguchi, Junji; Yanagisawa, Shuichi

    2017-01-29

    Nitrate modulates growth and development, functioning as a nutrient signal in plants. Although many changes in physiological processes in response to nitrate have been well characterized as nitrate responses, the molecular mechanisms underlying the nitrate response are not yet fully understood. Here, we show that NLP transcription factors, which are key regulators of the nitrate response, directly activate the nitrate-inducible expression of BT1 and BT2 encoding putative scaffold proteins with a plant-specific domain structure in Arabidopsis. Interestingly, the 35S promoter-driven expression of BT2 partially rescued growth inhibition caused by reductions in NLP activity in Arabidopsis. Furthermore, simultaneous disruption of BT1 and BT2 affected nitrate-dependent lateral root development. These results suggest that direct activation of BT1 and BT2 by NLP transcriptional activators is a key component of the molecular mechanism underlying the nitrate response in Arabidopsis. Copyright © 2016 Elsevier Inc. All rights reserved.

  1. 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.

  2. Bacterial communities of the cotton aphid Aphis gossypii associated with Bt cotton in northern China.

    Science.gov (United States)

    Zhao, Yao; Zhang, Shuai; Luo, Jun-Yu; Wang, Chun-Yi; Lv, Li-Min; Cui, Jin-Jie

    2016-04-15

    Aphids are infected with a wide variety of endosymbionts that can confer ecologically relevant traits. However, the bacterial communities of most aphid species are still poorly characterized. This study investigated the bacterial diversity of the cotton aphid Aphis gossypii associated with Bt cotton in northern China by targeting the V4 region of the 16S rDNA using the Illumina MiSeq platform. Our sequencing data revealed that bacterial communities of A. gossypii were generally dominated by the primary symbiont Buchnera, together with the facultative symbionts Arsenophonus and Hamiltonella. To our knowledge, this is the first report documenting the facultative symbiont Hamiltonella in A. gossypii. Moreover, the bacterial community structure was similar within aphids from the same province, but distinct among those from different provinces. The taxonomic diversity of the bacterial community is greater in Hebei Province compared with in samples from Henan and Shandong Provinces. The selection pressure exerted by the different geographical locations could explain the differences found among the various provinces. These findings broaden our understanding of the interactions among aphids, endosymbionts and their environments, and provide clues to develop potential biocontrol techniques against this cotton aphid.

  3. Test Takers' Writing Activities during the "TOEFL iBT"® Writing Tasks: A Stimulated Recall Study. "TOEFL iBT"® Research Report. TOEFL iBT-25. ETS Research Report No. RR-15-04

    Science.gov (United States)

    Barkaoui, Khaled

    2015-01-01

    This study aimed to describe the writing activities that test takers engage in when responding to the writing tasks in the "TOEFL iBT"[superscript R] test and to examine the effects of task type and test-taker English language proficiency (ELP) and keyboarding skills on the frequency and distribution of these activities. Each of 22 test…

  4. Stakeholders' Beliefs about the "TOEFL iBT"® Test as a Measure of Academic Language Ability. "TOEFL iBT"® Research Report. TOEFL iBT-22. ETS Research Report. RR-14-42

    Science.gov (United States)

    Malone, Margaret E.; Montee, Megan

    2014-01-01

    The "TOEFL iBT"® test presents test takers with tasks meant to simulate the tasks required of students in English-medium universities. Research establishing the validity argument for the test provides evidence for score interpretation and the use of the test for university admissions and placement. Now that the test has been operational…

  5. 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. © The Authors 2015. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

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

    National Research Council Canada - National Science Library

    Li, Guangsheng; Wang, Yongmo; Liu, Biao; Zhang, Guoan

    2014-01-01

    .... 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...

  7. Effects of ensiling of Bacillus thuringiensis (Bt) maize (MON810) on ...

    African Journals Online (AJOL)

    ajl yemi

    2011-11-30

    Bertoni and Marsan, 2005). The genetically modified organism (GMO) threshold level. (<1%) specified for labeling food and feed by the EU. (Saeglitz and Bartsch, 2003) could have implications on using Bt maize as animal feed, ...

  8. 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

  9. The effect of feeding Bt MON810 maize to pigs for 110 days on intestinal microbiota.

    Directory of Open Access Journals (Sweden)

    Stefan G Buzoianu

    Full Text Available OBJECTIVE: To assess the effects of feeding Bt MON810 maize to pigs for 110 days on the intestinal microbiota. METHODOLOGY/PRINCIPAL FINDINGS: Forty male pigs (∼40 days old were blocked by weight and litter ancestry and assigned to one of four treatments; 1 Isogenic maize-based diet for 110 days (Isogenic; 2 Bt maize-based diet (MON810 for 110 days (Bt; 3 Isogenic maize-based diet for 30 days followed by a Bt maize-based diet for 80 days (Isogenic/Bt; 4 Bt maize-based diet for 30 days followed by an isogenic maize-based diet for 80 days (Bt/Isogenic. Enterobacteriaceae, Lactobacillus and total anaerobes were enumerated in the feces using culture-based methods on days 0, 30, 60 and 100 of the study and in ileal and cecal digesta on day 110. No differences were found between treatments for any of these counts at any time point. The relative abundance of cecal bacteria was also determined using high-throughput 16 S rRNA gene sequencing. No differences were observed in any bacterial taxa between treatments, with the exception of the genus Holdemania which was more abundant in the cecum of pigs fed the isogenic/Bt treatment compared to pigs fed the Bt treatment (0.012 vs 0.003%; P≤0.05. CONCLUSIONS/SIGNIFICANCE: Feeding pigs a Bt maize-based diet for 110 days did not affect counts of any of the culturable bacteria enumerated in the feces, ileum or cecum. Neither did it influence the composition of the cecal microbiota, with the exception of a minor increase in the genus Holdemania. As the role of Holdemania in the intestine is still under investigation and no health abnormalities were observed, this change is not likely to be of clinical significance. These results indicate that feeding Bt maize to pigs in the context of its influence on the porcine intestinal microbiota is safe.

  10. Tritrophic Interactions: Microbe-Mediated Plant Effects on Insect Herbivores.

    Science.gov (United States)

    Shikano, Ikkei; Rosa, Cristina; Tan, Ching-Wen; Felton, Gary W

    2017-08-04

    It is becoming abundantly clear that the microbes associated with plants and insects can profoundly influence plant-insect interactions. Here, we focus on recent findings and propose directions for future research that involve microbe-induced changes to plant defenses and nutritive quality as well as the consequences of these changes for the behavior and fitness of insect herbivores. Insect (herbivore and parasitoid)-associated microbes can favor or improve insect fitness by suppressing plant defenses and detoxifying defensive phytochemicals. Phytopathogens can influence or manipulate insect behavior and fitness by altering plant quality and defense. Plant-beneficial microbes can promote plant growth and influence plant nutritional and phytochemical composition that can positively or negatively influence insect fitness. Lastly, we suggest that entomopathogens have the potential to influence plant defenses directly as endophytes or indirectly by altering insect physiology.

  11. Global climate change and above- belowground insect herbivore interactions.

    Directory of Open Access Journals (Sweden)

    Scott Wesley McKenzie

    2013-10-01

    Full Text Available Predicted changes to the Earth’s climate are likely to affect above-belowground interactions. Our understanding is limited, however, by past focus on two-species aboveground interactions mostly ignoring belowground influences. Despite their importance to ecosystem processes, there remains a dearth of empirical evidence showing how climate change will affect above-belowground interactions. The responses of above- and belowground organisms to climate change are likely to differ given the fundamentally different niches they inhabit. Yet there are few studies that address the biological and ecological reactions of belowground herbivores to environmental conditions in current and future climates. Even fewer studies investigate the consequences of climate change for above-belowground interactions between herbivores and other organisms; those that do provide no evidence of a directed response. This paper highlights the importance of considering the belowground fauna when making predictions on the effects of climate change on plant-mediated interspecific interactions.

  12. Plants respond to leaf vibrations caused by insect herbivore chewing.

    Science.gov (United States)

    Appel, H M; Cocroft, R B

    2014-08-01

    Plant germination and growth can be influenced by sound, but the ecological significance of these responses is unclear. We asked whether acoustic energy generated by the feeding of insect herbivores was detected by plants. We report that the vibrations caused by insect feeding can elicit chemical defenses. Arabidopsis thaliana (L.) rosettes pre-treated with the vibrations caused by caterpillar feeding had higher levels of glucosinolate and anthocyanin defenses when subsequently fed upon by Pieris rapae (L.) caterpillars than did untreated plants. The plants also discriminated between the vibrations caused by chewing and those caused by wind or insect song. Plants thus respond to herbivore-generated vibrations in a selective and ecologically meaningful way. A vibration signaling pathway would complement the known signaling pathways that rely on volatile, electrical, or phloem-borne signals. We suggest that vibration may represent a new long distance signaling mechanism in plant-insect interactions that contributes to systemic induction of chemical defenses.

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

    DEFF Research Database (Denmark)

    Berg, Thomas B.; Schmidt, Niels M.; Høye, Toke Thomas

    , the moth Sympistis zetterstedtii, the collared lemming Dicrostonyx groenlandicus and the musk ox Ovibos moschatus. Data from Zackenberg show that timing of snowmelt, the length of the growing season and summer temperature are the basic variables that determine the phenology of flowering and primary...... 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 directly...... 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 few moth larvae were...

  14. Simultaneous inbreeding modifies inbreeding depression in a plant-herbivore interaction.

    Science.gov (United States)

    Kalske, Aino; Mutikainen, Pia; Muola, Anne; Scheepens, J F; Laukkanen, Liisa; Salminen, Juha-Pekka; Leimu, Roosa

    2014-02-01

    Because inbreeding is common in natural populations of plants and their herbivores, herbivore-induced selection on plants, and vice versa, may be significantly modified by inbreeding and inbreeding depression. In a feeding assay with inbred and outbred lines of both the perennial herb, Vincetoxicum hirundinaria, and its specialist herbivore, Abrostola asclepiadis, we discovered that plant inbreeding increased inbreeding depression in herbivore performance in some populations. The effect of inbreeding on plant resistance varied among plant and herbivore populations. The among-population variation is likely to be driven by variation in plant secondary compounds across populations. In addition, inbreeding depression in plant resistance was substantial when herbivores were outbred, but diminished when herbivores were inbred. These findings demonstrate that in plant-herbivore interactions expression of inbreeding depression can depend on the level of inbreeding of the interacting species. Furthermore, our results suggest that when herbivores are inbred, herbivore-induced selection against self-fertilisation in plants may diminish. © 2013 John Wiley & Sons Ltd/CNRS.

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

    Science.gov (United States)

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

    2015-01-01

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

  16. Positive selection of digestive Cys proteases in herbivorous Coleoptera.

    Science.gov (United States)

    Vorster, Juan; Rasoolizadeh, Asieh; Goulet, Marie-Claire; Cloutier, Conrad; Sainsbury, Frank; Michaud, Dominique

    2015-10-01

    Positive selection is thought to contribute to the functional diversification of insect-inducible protease inhibitors in plants in response to selective pressures exerted by the digestive proteases of their herbivorous enemies. Here we assessed whether a reciprocal evolutionary process takes place on the insect side, and whether ingestion of a positively selected plant inhibitor may translate into a measurable rebalancing of midgut proteases in vivo. Midgut Cys proteases of herbivorous Coleoptera, including the major pest Colorado potato beetle (Leptinotarsa decemlineata), were first compared using a codon-based evolutionary model to look for the occurrence of hypervariable, positively selected amino acid sites among the tested sequences. Hypervariable sites were found, distributed within -or close to- amino acid regions interacting with Cys-type inhibitors of the plant cystatin protein family. A close examination of L. decemlineata sequences indicated a link between their assignment to protease functional families and amino acid identity at positively selected sites. A function-diversifying role for positive selection was further suggested empirically by in vitro protease assays and a shotgun proteomic analysis of L. decemlineata Cys proteases showing a differential rebalancing of protease functional family complements in larvae fed single variants of a model cystatin mutated at positively selected amino acid sites. These data confirm overall the occurrence of hypervariable, positively selected amino acid sites in herbivorous Coleoptera digestive Cys proteases. They also support the idea of an adaptive role for positive selection, useful to generate functionally diverse proteases in insect herbivores ingesting functionally diverse, rapidly evolving dietary cystatins. Copyright © 2015 Elsevier Ltd. All rights reserved.

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

    Directory of Open Access Journals (Sweden)

    Mitra Shariatinajafabadi

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

  18. 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

  19. 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

  20. 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...

  1. 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.

  2. The logistic model-generated carrying capacities for wild herbivores ...

    African Journals Online (AJOL)

    Jesse

    The general form of Equations (5c) is shown in Equations. (5d); these equations are independent of time. 1. 1. ) 1(. +. +. -. +. = it i it it. Yr. H. H. ,. (5d) for i = 1,…,n. From an ecological point of view, the rate of herbivore population growth per period (ri), is hypothesized to be determined by intra- and inter-species competition ...

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

    Directory of Open Access Journals (Sweden)

    Meret Huber

    2016-01-01

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

  4. 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. © The Author 2015. Published by Oxford University Press. All rights reserved. For permissions, please email: journals.permissions@oup.com.

  5. A QTL that enhances and broadens Bt insect resistance in soybean.

    Science.gov (United States)

    Walker, David R; Narvel, James M; Boerma, H Roger; All, John N; Parrott, Wayne A

    2004-09-01

    Effective strategies are needed to manage insect resistance to Bacillus thuringiensis (Bt) proteins expressed in transgenic crops. To evaluate a multiple resistance gene pyramiding strategy, eight soybean (Glycine max) lines possessing factorial combinations of two quantitative trait loci (QTLs) from plant introduction (PI) 229358 and a synthetic Bt cry1Ac gene were developed using marker-assisted selection with simple sequence repeat markers. Field studies were conducted in 2000 and 2001 to evaluate resistance to corn earworm (Helicoverpa zea) and soybean looper (Pseudoplusia includens), and detached leaf bioassays were used to test antibiosis resistance to Bt-resistant and Bt-susceptible strains of tobacco budworm (TBW; Heliothis virescens). Based on defoliation in the field and larval weight gain on detached leaves, lines carrying a combination of cry1Ac and the PI 229358 allele at a QTL on linkage group M were significantly more resistant to the lepidopteran pests, including the Bt-resistant TBW strain, than were the other lines. This is the first report of a complementary additive effect between a Bt transgene and a plant insect resistance QTL with an uncharacterized mode of action that was introgressed using marker-assisted selection.

  6. An Empirical Assessment of Transgene Flow from a Bt Transgenic Poplar Plantation.

    Directory of Open Access Journals (Sweden)

    Jianjun Hu

    Full Text Available To assess the possible impact of transgenic poplar plantations on the ecosystem, we analyzed the frequency and distance of gene flow from a mature male transgenic Populus nigra plantation carrying the Bacillus thuringiensis toxin gene (Bt poplar and the survival of Bt poplar seeds. The resultant Bt poplar seeds occurred at a frequency of ~0.15% at 0 m to ~0.02% at 500 m from the Bt poplar plantation. The germination of Bt poplar seeds diminished within three weeks in the field (germination rate from 68% to 0% compared to 48% after three weeks of storage at 4°C. The survival rate of seedlings in the field was 0% without any treatment but increased to 1.7% under the addition of four treatments (cleaning and trimming, watering, weeding, and covering with plastic film to maintain moisture after being seeded in the field for eight weeks. The results of this study indicate that gene flow originating from the Bt poplar plantation occurred at an extremely low level through pollen or seeds under natural conditions. This study provides first-hand field data on the extent of transgene flow in poplar plantations and offers guidance for the risk assessment of transgenic poplar plantations.

  7. The Potential Effect of Bt Maize on Chrysoperla pudica (Neuroptera: Chrysopidae).

    Science.gov (United States)

    Van Den Berg, J; Warren, J F; Du Plessis, H

    2017-04-01

    Previous studies into third trophic level exposure of Chrysoperla spp. (Neuroptera: Chrysopidae) to Cry1Ab proteins produced by Bt crops yielded contradicting results. These contradictions were largely ascribed to differences in prey quality and exposure methods. In this study, we used healthy prey to expose lacewing larvae to Cry1Ab protein produced by Bt maize, and also determined the concentration of this protein at different trophic levels. Experiments were conducted in which Chrysoperla pudica (Navás) larvae were fed different diets which included aphids and healthy Bt-resistant Busseola fusca (Fuller) (Lepidoptera: Noctuidae) larvae feeding on Bt maize tissue. Lacewing larval and pupal development times as well as overall mortality were determined. The concentration of Cry1Ab protein in B. fusca larvae were fourfold reduced compared with that in leaf tissue and was below detection level in lacewing larvae. Survival to the pupal stage was higher than 96% in all treatments. Larval and pupal development periods did not differ significantly between treatments in which prey fed on Bt or non-Bt maize. This study showed feeding on healthy prey that consumed Cry1Ab protein has no adverse effect on the biology of C. pudica. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  8. Benefits of Bt cotton counterbalanced by secondary pests? Perceptions of ecological change in China.

    Science.gov (United States)

    Zhao, Jennifer H; Ho, Peter; Azadi, Hossein

    2011-02-01

    In the past, scientific research has predicted a decrease in the effectiveness of Bt cotton due to the rise of secondary and other sucking pests. It is suspected that once the primary pest is brought under control, secondary pests have a chance to emerge due to the lower pesticide applications in Bt cotton cultivars. Studies on this phenomenon are scarce. This article furnishes empirical evidence that farmers in China perceive a substantial increase in secondary pests after the introduction of Bt cotton. The research is based on a survey of 1,000 randomly selected farm households in five provinces in China. We found that the reduction in pesticide use in Bt cotton cultivars is significantly lower than that reported in research elsewhere. This is consistent with the hypothesis suggested by recent studies that more pesticide sprayings are needed over time to control emerging secondary pests, such as aphids, spider mites, and lygus bugs. Apart from farmers' perceptions of secondary pests, we also assessed their basic knowledge of Bt cotton and their perceptions of Bt cotton in terms of its strengths and shortcomings (e.g., effectiveness, productivity, price, and pesticide use) in comparison with non-transgenic cotton.

  9. 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.

  10. Conserving herbivorous and predatory insects in urban green spaces

    Science.gov (United States)

    Mata, Luis; Threlfall, Caragh G.; Williams, Nicholas S. G.; Hahs, Amy K.; Malipatil, Mallik; Stork, Nigel E.; Livesley, Stephen J.

    2017-01-01

    Insects are key components of urban ecological networks and are greatly impacted by anthropogenic activities. Yet, few studies have examined how insect functional groups respond to changes to urban vegetation associated with different management actions. We investigated the response of herbivorous and predatory heteropteran bugs to differences in vegetation structure and diversity in golf courses, gardens and parks. We assessed how the species richness of these groups varied amongst green space types, and the effect of vegetation volume and plant diversity on trophic- and species-specific occupancy. We found that golf courses sustain higher species richness of herbivores and predators than parks and gardens. At the trophic- and species-specific levels, herbivores and predators show strong positive responses to vegetation volume. The effect of plant diversity, however, is distinctly species-specific, with species showing both positive and negative responses. Our findings further suggest that high occupancy of bugs is obtained in green spaces with specific combinations of vegetation structure and diversity. The challenge for managers is to boost green space conservation value through actions promoting synergistic combinations of vegetation structure and diversity. Tackling this conservation challenge could provide enormous benefits for other elements of urban ecological networks and people that live in cities. PMID:28102333

  11. Conserving herbivorous and predatory insects in urban green spaces.

    Science.gov (United States)

    Mata, Luis; Threlfall, Caragh G; Williams, Nicholas S G; Hahs, Amy K; Malipatil, Mallik; Stork, Nigel E; Livesley, Stephen J

    2017-01-19

    Insects are key components of urban ecological networks and are greatly impacted by anthropogenic activities. Yet, few studies have examined how insect functional groups respond to changes to urban vegetation associated with different management actions. We investigated the response of herbivorous and predatory heteropteran bugs to differences in vegetation structure and diversity in golf courses, gardens and parks. We assessed how the species richness of these groups varied amongst green space types, and the effect of vegetation volume and plant diversity on trophic- and species-specific occupancy. We found that golf courses sustain higher species richness of herbivores and predators than parks and gardens. At the trophic- and species-specific levels, herbivores and predators show strong positive responses to vegetation volume. The effect of plant diversity, however, is distinctly species-specific, with species showing both positive and negative responses. Our findings further suggest that high occupancy of bugs is obtained in green spaces with specific combinations of vegetation structure and diversity. The challenge for managers is to boost green space conservation value through actions promoting synergistic combinations of vegetation structure and diversity. Tackling this conservation challenge could provide enormous benefits for other elements of urban ecological networks and people that live in cities.

  12. Macroevolution and the biological diversity of plants and herbivores

    Science.gov (United States)

    Futuyma, Douglas J.; Agrawal, Anurag A.

    2009-01-01

    Terrestrial biodiversity is dominated by plants and the herbivores that consume them, and they are one of the major conduits of energy flow up to higher trophic levels. Here, we address the processes that have generated the spectacular diversity of flowering plants (>300,000 species) and insect herbivores (likely >1 million species). Long-standing macroevolutionary hypotheses have postulated that reciprocal evolution of adaptations and subsequent bursts of speciation have given rise to much of this biodiversity. We critically evaluate various predictions based on this coevolutionary theory. Phylogenetic reconstruction of ancestral states has revealed evidence for escalation in the potency or variety of plant lineages' chemical defenses; however, escalation of defense has been moderated by tradeoffs and alternative strategies (e.g., tolerance or defense by biotic agents). There is still surprisingly scant evidence that novel defense traits reduce herbivory and that such evolutionary novelty spurs diversification. Consistent with the coevolutionary hypothesis, there is some evidence that diversification of herbivores has lagged behind, but has nevertheless been temporally correlated with that of their host-plant clades, indicating colonization and radiation of insects on diversifying plants. However, there is still limited support for the role of host-plant shifts in insect diversification. Finally, a frontier area of research, and a general conclusion of our review, is that community ecology and the long-term evolutionary history of plant and insect diversification are inexorably intertwined. PMID:19815508

  13. Large herbivores surf waves of green-up during spring.

    Science.gov (United States)

    Merkle, Jerod A; Monteith, Kevin L; Aikens, Ellen O; Hayes, Matthew M; Hersey, Kent R; Middleton, Arthur D; Oates, Brendan A; Sawyer, Hall; Scurlock, Brandon M; Kauffman, Matthew J

    2016-06-29

    The green wave hypothesis (GWH) states that migrating animals should track or 'surf' high-quality forage at the leading edge of spring green-up. To index such high-quality forage, recent work proposed the instantaneous rate of green-up (IRG), i.e. rate of change in the normalized difference vegetation index over time. Despite this important advancement, no study has tested the assumption that herbivores select habitat patches at peak IRG. We evaluated this assumption using step selection functions parametrized with movement data during the green-up period from two populations each of bighorn sheep, mule deer, elk, moose and bison, totalling 463 individuals monitored 1-3 years from 2004 to 2014. Accounting for variables that typically influence habitat selection for each species, we found seven of 10 populations selected patches exhibiting high IRG-supporting the GWH. Nonetheless, large herbivores selected for the leading edge, trailing edge and crest of the IRG wave, indicating that other mechanisms (e.g. ruminant physiology) or measurement error inherent with satellite data affect selection for IRG. Our evaluation indicates that IRG is a useful tool for linking herbivore movement with plant phenology, paving the way for significant advancements in understanding how animals track resource quality that varies both spatially and temporally. © 2016 The Author(s).

  14. Herbivorous ecomorphology and specialization patterns in theropod dinosaur evolution.

    Science.gov (United States)

    Zanno, Lindsay E; Makovicky, Peter J

    2011-01-04

    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.

  15. Diversity and stability of herbivorous fishes on coral reefs.

    Science.gov (United States)

    Thibaut, Loic M; Connolly, Sean R; Sweatman, Hugh P A

    2012-04-01

    Biodiversity may provide insurance against ecosystem collapse by stabilizing assemblages that perform particular ecological functions (the "portfolio effect"). However, the extent to which this occurs in nature and the importance of different mechanisms that generate portfolio effects remain controversial. On coral reefs, herbivory helps maintain coral dominated states, so volatility in levels of herbivory has important implications for reef ecosystems. Here, we used an extensive time series of abundances on 35 reefs of the Great Barrier Reef of Australia to quantify the strength of the portfolio effect for herbivorous fishes. Then, we disentangled the contributions of two mechanisms that underlie it (compensatory interactions and differential responses to environmental fluctuations ["response diversity"]) by fitting a community-dynamic model that explicitly includes terms for both mechanisms. We found that portfolio effects operate strongly in herbivorous fishes, as shown by nearly independent fluctuations in abundances over time. Moreover, we found strong evidence for high response diversity, with nearly independent responses to environmental fluctuations. In contrast, we found little evidence that the portfolio effect in this system was enhanced by compensatory ecological interactions. Our results show that portfolio effects are driven principally by response diversity for herbivorous fishes on coral reefs. We conclude that portfolio effects can be very strong in nature and that, for coral reefs in particular, response diversity may help maintain herbivory above the threshold levels that trigger regime shifts.

  16. Macroevolution and the biological diversity of plants and herbivores.

    Science.gov (United States)

    Futuyma, Douglas J; Agrawal, Anurag A

    2009-10-27

    Terrestrial biodiversity is dominated by plants and the herbivores that consume them, and they are one of the major conduits of energy flow up to higher trophic levels. Here, we address the processes that have generated the spectacular diversity of flowering plants (>300,000 species) and insect herbivores (likely >1 million species). Long-standing macroevolutionary hypotheses have postulated that reciprocal evolution of adaptations and subsequent bursts of speciation have given rise to much of this biodiversity. We critically evaluate various predictions based on this coevolutionary theory. Phylogenetic reconstruction of ancestral states has revealed evidence for escalation in the potency or variety of plant lineages' chemical defenses; however, escalation of defense has been moderated by tradeoffs and alternative strategies (e.g., tolerance or defense by biotic agents). There is still surprisingly scant evidence that novel defense traits reduce herbivory and that such evolutionary novelty spurs diversification. Consistent with the coevolutionary hypothesis, there is some evidence that diversification of herbivores has lagged behind, but has nevertheless been temporally correlated with that of their host-plant clades, indicating colonization and radiation of insects on diversifying plants. However, there is still limited support for the role of host-plant shifts in insect diversification. Finally, a frontier area of research, and a general conclusion of our review, is that community ecology and the long-term evolutionary history of plant and insect diversification are inexorably intertwined.

  17. 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…

  18. 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...

  19. 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…

  20. Effects of feeding Bt MON810 maize to pigs for 110 days on peripheral immune response and digestive fate of the cry1Ab gene and truncated Bt toxin.

    Science.gov (United States)

    Walsh, Maria C; Buzoianu, Stefan G; Rea, Mary C; O'Donovan, Orla; Gelencsér, Eva; Ujhelyi, Gabriella; Ross, R Paul; Gardiner, Gillian E; Lawlor, Peadar G

    2012-01-01

    The objective of this study was to evaluate potential long-term (110 days) and age-specific effects of feeding genetically modified Bt maize on peripheral immune response in pigs and to determine the digestive fate of the cry1Ab gene and truncated Bt toxin. Forty day old pigs (n = 40) were fed one of the following treatments: 1) isogenic maize-based diet for 110 days (isogenic); 2) Bt maize-based diet (MON810) for 110 days (Bt); 3) Isogenic maize-based diet for 30 days followed by Bt maize-based diet for 80 days (isogenic/Bt); and 4) Bt maize-based diet (MON810) for 30 days followed by isogenic maize-based diet for 80 days (Bt/isogenic). Blood samples were collected during the study for haematological analysis, measurement of cytokine and Cry1Ab-specific antibody production, immune cell phenotyping and cry1Ab gene and truncated Bt toxin detection. Pigs were sacrificed on day 110 and digesta and organ samples were taken for detection of the cry1Ab gene and the truncated Bt toxin. On day 100, lymphocyte counts were higher (PBt/isogenic than pigs fed Bt or isogenic. Erythrocyte counts on day 100 were lower in pigs fed Bt or isogenic/Bt than pigs fed Bt/isogenic (PBt toxin nor the cry1Ab gene were detected in the organs or blood of pigs fed Bt maize. The cry1Ab gene was detected in stomach digesta and at low frequency in the ileum but not in the distal gastrointestinal tract (GIT), while the Bt toxin fragments were detected at all sites in the GIT. Perturbations in peripheral immune response were thought not to be age-specific and were not indicative of Th 2 type allergenic or Th 1 type inflammatory responses. There was no evidence of cry1Ab gene or Bt toxin translocation to organs or blood following long-term feeding.

  1. Intraspecific chemical diversity among neighbouring plants correlates positively with plant size and herbivore load but negatively with herbivore damage.

    Science.gov (United States)

    Bustos-Segura, Carlos; Poelman, Erik H; Reichelt, Michael; Gershenzon, Jonathan; Gols, Rieta

    2017-01-01

    Intraspecific plant diversity can modify the properties of associated arthropod communities and plant fitness. However, it is not well understood which plant traits determine these ecological effects. We explored the effect of intraspecific chemical diversity among neighbouring plants on the associated invertebrate community and plant traits. In a common garden experiment, intraspecific diversity among neighbouring plants was manipulated using three plant populations of wild cabbage that differ in foliar glucosinolates. Plants were larger, harboured more herbivores, but were less damaged when plant diversity was increased. Glucosinolate concentration differentially correlated with generalist and specialist herbivore abundance. Glucosinolate composition correlated with plant damage, while in polycultures, variation in glucosinolate concentrations among neighbouring plants correlated positively with herbivore diversity and negatively with plant damage levels. The results suggest that intraspecific variation in secondary chemistry among neighbouring plants is important in determining the structure of the associated insect community and positively affects plant performance. © 2016 The Authors. Ecology Letters published by CNRS and John Wiley & Sons Ltd.

  2. 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.

  3. Insect herbivores, density dependence, and the performance of the perennial herb Solanum carolinense.

    Science.gov (United States)

    Underwood, Nora; Halpern, Stacey L

    2012-05-01

    How insect herbivores affect plant performance is of central importance to basic and applied ecology. A full understanding of herbivore effects on plant performance requires understanding interactions (if any) of herbivore effects with plant density and size because these interactions will be critical for determining how herbivores influence plant population size. However, few studies have considered these interactions, particularly over a wide enough range of densities to detect nonlinear effects. Here we ask whether plant density and herbivores influence plant performance linearly or nonlinearly, how plant density affects herbivore damage, and how herbivores alter density dependence in transitions between plant size classes. In a large field experiment, we manipulated the density of the herbaceous perennial plant Solanum carolinense and herbivore presence in a fully crossed design. We measured plant size, sexual reproduction, and damage to plants in two consecutive years, and asexual reproduction of new stems in the second year, allowing us to characterize both plant performance and rates of transition between plant size classes across years. We found nonlinear effects of plant density on damage. Damage by herbivores and plant density both influenced sexual and asexual reproduction of S. carolinense; these effects were mostly mediated via effects on plant size. Importantly, we found that herbivores altered the pattern of linear density dependence in some transition rates (including survival and asexual reproduction) between plant size classes. These results suggest that understanding the ecological or evolutionary effects of herbivores on plant populations requires consideration of plant density and plant size, because feedbacks between density, herbivores, and plant size may complicate longer-term dynamics.

  4. Effects of Bt maize-fed prey on the generalist predator Poecilus cupreus L. (Coleoptera: Carabidae).

    Science.gov (United States)

    Meissle, Michael; Vojtech, Eva; Poppy, Guy M

    2005-04-01

    We investigated the effects of transgenic maize (Zea mays) expressing Bacillus thuringienses toxin (Bt maize) on larval and adult Poecilus cupreus carabid beetles in laboratory studies. In no-choice trials, neonate P. cupreus larvae were fed exclusively with Spodoptera littoralis caterpillars, which had been raised on Bt maize. S. littoralis raised on conventional maize or "high quality" Calliphora sp. pupae were fed to the beetle larvae in two control treatments. Bt-maize-fed caterpillar prey increased mortality to 100% within 40 days. The experiment was repeated with 10-day-old beetle larvae. Bt treatment resulted in fewer pupae than in both controls, and in a higher mortality than in the Calliphora control. S. littoralis was suitable as exclusive prey in no-choice tests, at least for 40 days, although prey quality seemed to be low compared to Calliphora pupae. The observed effects are most likely indirect effects due to further reduced nutritional prey quality. However, direct effects cannot be excluded. In the second part of the study, exposure of P. cupreus to Bt intoxicated prey was examined in paired-choice tests. Adult beetles were offered a choice between different prey conditions (frozen and thawed, freshly killed or living), prey types (S. littoralis caterpillars, Calliphora sp. pupae, cereal aphids) and prey treatments (raised on Bt or conventional maize). Living prey was preferred to frozen and dead prey. Caterpillars were only preferred to fly pupae and aphids when living. Prey treatment seemed to be least important for prey selection. The tests showed that P. cupreus ingested caterpillars readily and there was no evidence of them avoiding Bt containing prey, which means exposure in the field could occur. The presented protocols are a first step towards ecological risk assessment for carabid beetles.

  5. Global patterns in the structure and robustness of plant-herbivore networks

    Directory of Open Access Journals (Sweden)

    Walter Santos de Araújo

    2016-10-01

    Full Text Available My goal is to investigate global patterns in the structure of interaction networks of insect herbivores and their host plants. Specifically, I seek to determine whether intensification of land use and the dominance of exotic host plant species influence the structure and robustness (i.e., resistance to co-extinctions of interaction networks of insect herbivores and host plants. I also ask whether latitude has an influence on the structure and robustness of these interactions. I compiled 90 local plant-herbivore networks distributed worldwide, spanning different taxonomic groups of plants and insects and several herbivore guilds. My results showed that intensification of land use was associated with dominance of exotic plant species and can impoverish the species richness and taxonomic diversity of insect herbivores in the networks. Moreover, land use intensification surprisingly increases network specialization by decreasing connectance and nestedness, and increases modularity; while the increase in the proportion of exotic hosts had opposite effects. These changes in the network structure may be due to the proportionately greater loss of generalist herbivores relative to specialists. Land use intensification also decreases the robustness of plant-herbivore networks, while the proportion of exotic host plant species increases, which is an intriguing result that contradicts previous studies. Controlling for anthropic effects that can act on the networks, my results show that plant–herbivore networks are structured independently of latitude, suggesting that the factors that influence the interactions between host plants and insect herbivores are latitudinally invariant.

  6. Effects of large-scale gold mining on migratory behavior of a large herbivore

    National Research Council Canada - National Science Library

    Blum, Marcus E; Stewart, Kelley M; Schroeder, Cody

    2015-01-01

    .... Mineral exploration and other types of development may adversely affect migratory corridors for large herbivores, but little is known about functional effects on migratory behavior and resource selection...

  7. Herbivore dung deposit counts around drinking troughs in the Kruger National Park

    Directory of Open Access Journals (Sweden)

    I. Thrash

    1993-09-01

    Full Text Available The density of deposits of dung of indigenous large herbivores was measured in transects starting at drinking troughs in the Kruger National Park. The aim was to test whether a relationship exists between intensity of (large indigenous herbivore use and distance from drinking troughs. There was a significant positive relationship between intensity of herbivore use and'distance from the troughs. The variance was too high, however, to detect relationships at individual transects or to warrant further modelling of the relationship. It was concluded that there was indeed a slight concentration of large herbivore rangeland use around the troughs.

  8. 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).…

  9. Impact of corn earworm injury on yield of transgenic corn producing Bt toxins in the Carolinas.

    Science.gov (United States)

    Reay-Jones, Francis P F; Reisig, Dominic D

    2014-06-01

    Transgenic corn, Zea mays L., hybrids expressing insecticidal Cry proteins from Bacillus thuringiensis (Bt) and insecticide applications to suppress injury from Helicoverpa zea (Boddie) were evaluated in Florence, SC, and in Plymouth, NC, in 2012 and 2013. Based on kernel area injured, insecticide applications (chlorantraniliprole) every 3-4 d from R1 until H. zea had cycled out of corn reduced injury by 80-93% in Florence and 94-95% in Plymouth. Despite intensive applications of insecticide (13-18 per trial), limited injury still occurred in all treated plots in 2012, except in DKC 68-03 (Genuity VT Double PRO), based on kernels injured (both locations) and proportion of injured ears (Florence only). In 2013, ear injury was low in Plymouth, with no kernel injury in any insecticide-treated plots, except P1498R (non-Bt) and P1498YHR (Optimum Intrasect). Injury in Florence in 2013 did not occur in treated plots of DKC 68-04 (non-Bt), DKC 68-03 (Genuity VT Double PRO), and N785-3111 (Agrisure Viptera). Yields were not significantly affected by insecticide treatment and were not statistically different among near-isolines with and without Bt traits. Yields were not significantly associated with kernel injury based on regression analyses. The value of using Bt corn hybrids to manage H. zea is discussed.

  10. Fitness cost of resistance to Bt cotton linked with increased gossypol content in pink bollworm larvae.

    Directory of Open Access Journals (Sweden)

    Jennifer L Williams

    Full Text Available Fitness costs of resistance to Bacillus thuringiensis (Bt crops occur in the absence of Bt toxins, when individuals with resistance alleles are less fit than individuals without resistance alleles. As costs of Bt resistance are common, refuges of non-Bt host plants can delay resistance not only by providing susceptible individuals to mate with resistant individuals, but also by selecting against resistance. Because costs typically vary across host plants, refuges with host plants that magnify costs or make them less recessive could enhance resistance management. Limited understanding of the physiological mechanisms causing fitness costs, however, hampers attempts to increase costs. In several major cotton pests including pink bollworm (Pectinophora gossypiella, resistance to Cry1Ac cotton is associated with mutations altering cadherin proteins that bind this toxin in susceptible larvae. Here we report that the concentration of gossypol, a cotton defensive chemical, was higher in pink bollworm larvae with cadherin resistance alleles than in larvae lacking such alleles. Adding gossypol to the larval diet decreased larval weight and survival, and increased the fitness cost affecting larval growth, but not survival. Across cadherin genotypes, the cost affecting larval growth increased as the gossypol concentration of larvae increased. These results suggest that increased accumulation of plant defensive chemicals may contribute to fitness costs associated with resistance to Bt toxins.

  11. 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

  12. Stable isotope signatures of large herbivore foraging habitats across Europe.

    Science.gov (United States)

    Hofman-Kamińska, Emilia; Bocherens, Hervé; Borowik, Tomasz; Drucker, Dorothée G; Kowalczyk, Rafał

    2018-01-01

    We investigated how do environmental and climatic factors, but also management, affect the carbon (δ13C) and nitrogen (δ15N) stable isotope composition in bone collagen of the two largest contemporary herbivores: European bison (Bison bonasus) and moose (Alces alces) across Europe. We also analysed how different scenarios of population recovery- reintroduction in bison and natural recovery in moose influenced feeding habitats and diet of these two species and compared isotopic signatures of modern populations of bison and moose (living in human-altered landscapes) with those occurring in early Holocene. We found that δ13C of modern bison and moose decreased with increasing forest cover. Decreasing forest cover, increasing mean annual temperature and feeding on farm crops caused an increase in δ15N in bison, while no factor significantly affected δ15N in moose. We showed significant differences in δ13C and δ15N among modern bison populations, in contrast to moose populations. Variation in both isotopes in bison resulted from inter-population differences, while in moose it was mainly an effect of intra-population variation. Almost all modern bison populations differed in δ13C and δ15N from early Holocene bison. Such differences were not observed in moose. It indicates refugee status of European bison. Our results yielded evidence that habitat structure, management and a different history of population recovery have a strong influence on foraging behaviour of large herbivores reflected in stable isotope signatures. Influence of forest structure on carbon isotope signatures of studied herbivores supports the "canopy effect" hypothesis.

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

    Science.gov (United States)

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

    2014-12-07

    Inbreeding can profoundly affect the interactions of plants with herbivores as well as with the natural enemies of the herbivores. We studied how plant inbreeding affects herbivore oviposition preference, and whether inbreeding of both plants and herbivores alters the probability of predation or parasitism of herbivore eggs. In a laboratory preference test with the specialist herbivore moth Abrostola asclepiadis and inbred and outbred Vincetoxicum hirundinaria plants, we discovered that herbivores preferred to oviposit on outbred plants. A field experiment with inbred and outbred plants that bore inbred or outbred herbivore eggs revealed that the eggs of the outbred herbivores were more likely to be lost by predation, parasitism or plant hypersensitive responses than inbred eggs. This difference did not lead to differences in the realized fecundity as the number of hatched larvae did not differ between inbred and outbred herbivores. Thus, the strength of inbreeding depression in herbivores decreases when their natural enemies are involved. Plant inbreeding did not alter the attraction of natural enemies of the eggs. We conclude that inbreeding can significantly alter the interactions of plants and herbivores at different life-history stages, and that some of these alterations are mediated by the natural enemies of the herbivores. © 2014 The Author(s) Published by the Royal Society. All rights reserved.

  14. The stoichiometry of nutrient release by terrestrial herbivores and its ecosystem consequences

    Science.gov (United States)

    Sitters, Judith; Bakker, Elisabeth S.; Veldhuis, Michiel P.; Veen, G. F.; Olde Venterink, Harry; Vanni, Michael J.

    2017-04-01

    It is widely recognized that the release of nutrients by herbivores via their waste products strongly impacts nutrient availability for autotrophs. The ratios of nitrogen (N) and phosphorus (P) recycled through herbivore release (i.e., waste N:P) are mainly determined by the stoichiometric composition of the herbivore’s food (food N:P) and its body nutrient content (body N:P). Waste N:P can in turn impact autotroph nutrient limitation and productivity. Herbivore-driven nutrient recycling based on stoichiometric principles is dominated by theoretical and experimental research in freshwater systems, in particular interactions between algae and invertebrate herbivores. In terrestrial ecosystems, the impact of herbivores on nutrient cycling and availability is often limited to studying carbon (C ):N and C:P ratios, while the role of terrestrial herbivores in mediating N:P ratios is also likely to influence herbivore-driven nutrient recycling. In this review, we use rules and predictions on the stoichiometry of nutrient release originating from algal-based aquatic systems to identify the factors that determine the stoichiometry of nutrient release by herbivores. We then explore how these rules can be used to understand the stoichiometry of nutrient release by terrestrial herbivores, ranging from invertebrates to mammals, and its impact on plant nutrient limitation and productivity. Future studies should focus on measuring both N and P when investigating herbivore-driven nutrient recycling in terrestrial ecosystems, while also taking the form of waste product (urine or feces) and other pathways by which herbivores change nutrients into account, to be able to quantify the impact of waste stoichiometry on plant communities.

  15. An economic evaluation of impact of soil quality on Bt (Bacillus thuringiensis cotton productivity

    Directory of Open Access Journals (Sweden)

    Muhammad Abid*, Muhammad Ashfaq, Imran Khalid and Usman Ishaq

    2011-04-01

    Full Text Available The study was conducted with the aim to determine the impact of soil quality on the Bt cotton productivity. Asample of 150 farmers was selected by using multi-stage sampling technique from three districts i.e. Rahim YarKhan, Multan and Mianwali. A Cobb Douglas production function was employed to assess the effect of variousagronomic and demographic variables on the Bt cotton productivity. Results of the analysis indicated that landpreparation cost, seed cost, fertilizer cost, labour cost and dummy variable of soil quality were significant andpositively contributing towards higher Bt cotton yield. While the spray cost and irrigation cost variable were foundpositive but non-significant. Findings of the study suggested that focusing on maintaining and improving the qualityof soils is necessary to obtain higher crop yields. All this needs attention of agricultural extension department toprovide information about advance techniques to farmers for improving soil quality.

  16. Uptake and transfer of a Bt toxin by a Lepidoptera to its eggs and effects on its offspring.

    Directory of Open Access Journals (Sweden)

    Débora Pires Paula

    Full Text Available Research on non-target effects of transgenic crop plants has focused primarily on bitrophic, tritrophic and indirect effects of entomotoxins from Bacillus thuringiensis, but little work has considered intergenerational transfer of Cry proteins. This work reports a lepidopteran (Chlosyne lacinia taking up a Bt entomotoxin when exposed to sublethal or low concentrations, transferring the entomotoxin to eggs, and having adverse effects on the first filial generation (F1 offspring. Two bioassays were conducted using a sublethal concentration of toxin (100.0 ng/µl Cry1Ac for adults and a concentration equal to the LC10 (2.0 ng/µl Cry1Ac for larvae. Cry1Ac is the most common entomotoxin expressed in Bt cotton in Brazil. In the adult diet bioassay there was no adverse effect on the parental generation (P0 adults, but the F1 larvae had higher mortality and longer development time compared to F1 larvae of parents that did not ingest Cry1Ac. For the 3rd instar larvae, there was no measurable effect on the P0 larvae, pupae and adults, but the F1 larvae had higher mortality and longer development time. Using chemiluminescent Western Blot, Cry1Ac was detected in F1 eggs laid by P0 butterflies from both bioassays. Our study indicates that, at least for this species and these experimental conditions, a ∼65 kDa insecticidal protein can be taken up and transferred to descendants where it can increase mortality and development time.

  17. Control of ferroelectric phase transition in nano particulate NBT–BT based ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Devi, Ch. Sameera; Kumar, G.S. [Department of Physics, Osmania University, Hyderabad 500 007 (India); Prasad, G., E-mail: gudurup@gmail.com [Department of Physics, Osmania University, Hyderabad 500 007 (India)

    2013-03-20

    Graphical abstract: Modified Curie–Weiss law fitting of BT1, NBT1, NBT2 and NBT3 samples and inset shows modified Curie–Weiss law fitting for NBT at 10 kHz frequency. Highlights: ► For the first time we have studied the effect of Nd{sup 3+} and BT on structural changes in NBT lattice. ► Ti metal powder was used instead of TiO{sub 2} to synthesize the ceramics using sol–gel. ► FTIR and Raman spectra were recorded for NBT–BT based ceramics. ► In dielectric measurements the transition from relaxor to normal with doping is observed. -- Abstract: Lead free relaxor NBT–BT based ceramic compositions were prepared using sol–gel method. The samples were sintered around 1140 °C for 3–4 h in the air. The characterization was done using X-ray diffraction (XRD), filed emission scanning electron microscope (FESEM), energy dispersive spectrometry (EDS), Raman, Fourier transform infrared (FTIR), dielectric and P–E loop measurements. The XRD patterns recorded at room temperature confirmed the phase formation of the samples. From FESEM micrographs, the particle sizes were estimated for calcined powders and are found to be in the range of 50–70 nm. The analysis of both Raman and FTIR spectral data of the samples also indicated the distortion of NBT lattice with the addition of Ba{sup 2+} and Nd{sup 3+} ions. It was found that the dielectric and piezoelectric properties of NBT–BT compositions beyond the morphotrophic phase boundary (MPB) are rather sensitive to the presence of tetragonal phase in addition to the rhombohedral phase. NBT ceramics exhibit a decrease in diffusive factor with increasing BT content, implying a degradation of relaxor feature leading to the normal ferroelectric nature. The ceramic samples employed in the present study exhibited variation in P–E hysteresis loops.

  18. Aboveground and belowground mammalian herbivores regulate the demography of deciduous woody species in conifer forests

    Science.gov (United States)

    Bryan A. Endress; Bridgett J. Naylor; Burak K. Pekin; Michael J. Wisdom

    2016-01-01

    Mammalian herbivory can have profound impacts on plant population and community dynamics. However, our understanding of specific herbivore effects remains limited, even in regions with high densities of domestic and wild herbivores, such as the semiarid conifer forests of western North America. We conducted a seven-year manipulative experiment to evaluate the effects...

  19. Plant chemical defense against herbivores and pathogens: generalized defense or trade-offs?

    NARCIS (Netherlands)

    Biere, A.; Marak, H.B.; Van Damme, J.M.M.

    2004-01-01

    Plants are often attacked by multiple enemies, including pathogens and herbivores. While many plant secondary metabolites show specific effects toward either pathogens or herbivores, some can affect the performance of both these groups of natural enemies and are considered to be generalized defense

  20. Rabbits, refuges and resources : how foraging of herbivores is affected by living in burrows

    NARCIS (Netherlands)

    Dekker, J.J.A.

    2007-01-01

    Small herbivores such as rabbits, pika and marmots create spatial patterns in vegetation around their burrows by grazing. This PhD thesis focuses on these refuge-living herbivores.By performing experiments with rabbits, he showed that looking for predators causes the spatial

  1. An ecological cost of plant defence : attractiveness of bitter cucumber plants to natural enemies of herbivores

    NARCIS (Netherlands)

    Agrawal, A.A.; Janssen, A.; Bruin, J.; Posthumus, M.A.; Sabelis, M.W.

    2002-01-01

    Plants produce defences that act directly on herbivores and indirectly via the attraction of natural enemies of herbivores. We examined the pleiotropic effects of direct chemical defence production on indirect defence employing near-isogenic varieties of cucumber plants (Cucumis sativus) that differ

  2. Native herbivore exerts contrasting effects on fire regime and vegetation structure

    Science.gov (United States)

    Jose L. Hierro; Kenneth L. Clark; Lyn C. Branch; Diego. Villarreal

    2011-01-01

    Although native herbivores can alter fire regimes by consuming herbaceous vegetation that serves as fine fuel and, less commonly, accumulating fuel as nest material and other structures, simultaneous considerations of contrasting effects of herbivores on fire have scarcely been addressed. We proposed that a colonial rodent, vizcacha (Lagostomus maximus...

  3. Linkages between grazing history and herbivore exclusion on decomposition rates in mineral soils of subalpine grasslands

    Science.gov (United States)

    Alan G. Haynes; Martin Schutz; Nina Buchmann; Deborah S. Page-Dumroese; Matt D. Busse; Anita C. Risch

    2014-01-01

    Herbivore-driven changes to soil properties can influence the decomposition rate of organic material and therefore soil carbon cycling within grassland ecosystems. We investigated how aboveground foraging mammalian and invertebrate herbivores affect mineral soil decomposition rates and associated soil properties in two subalpine vegetation types (shortgrass and tall-...

  4. Troublesome toxins: time to re-think plant-herbivore interactions in vertebrate ecology

    Directory of Open Access Journals (Sweden)

    Feng Zhilan

    2009-02-01

    Full Text Available Abstract Earlier models of plant-herbivore interactions relied on forms of functional response that related rates of ingestion by herbivores to mechanical or physical attributes such as bite size and rate. These models fail to predict a growing number of findings that implicate chemical toxins as important determinants of plant-herbivore dynamics. Specifically, considerable evidence suggests that toxins set upper limits on food intake for many species of herbivorous vertebrates. Herbivores feeding on toxin-containing plants must avoid saturating their detoxification systems, which often occurs before ingestion rates are limited by mechanical handling of food items. In light of the importance of plant toxins, a new approach is needed to link herbivores to their food base. We discuss necessary features of such an approach, note recent advances in herbivore functional response models that incorporate effects of plant toxins, and mention predictions that are consistent with observations in natural systems. Future ecological studies will need to address explicitly the importance of plant toxins in shaping plant and herbivore communities.

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

    NARCIS (Netherlands)

    Fei, M.; Gols, R.; Zhu, F.; Harvey, J.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

  6. Mechanisms and ecological implications of plant-mediated interactions between belowground and aboveground insect herbivores

    NARCIS (Netherlands)

    Papadopoulou, G.V.; Dam, N.M. van

    2017-01-01

    Plant-mediated interactions between belowground (BG) and aboveground (AG) herbivores have received increasing interest recently. However, the molecular mechanisms underlying ecological consequences of BG–AG interactions are not fully clear yet. Herbivore-induced plant defenses are complex and

  7. 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

    viruses and non-vectoring herbivores. We investigated the effects of virus infection on subsequent infestation by a non-vectoring herbivore in a natural genotype of Trifolium repens (white clover). We tested whether infection with White clover mosaic virus (WClMV) alters (1) the effects of fungus gnat...

  8. Plant defences limit herbivore population growth by changing predator-prey interactions.

    Science.gov (United States)

    Kersch-Becker, Mônica F; Kessler, André; Thaler, Jennifer S

    2017-09-13

    Plant quality and predators are important factors affecting herbivore population growth, but how they interact to regulate herbivore populations is not well understood. We manipulated jasmonate-induced plant resistance, exposure to the natural predator community and herbivore density to test how these factors jointly and independently affect herbivore population growth. On low-resistance plants, the predator community was diverse and abundant, promoting high predator consumption rates. On high-resistance plants, the predator community was less diverse and abundant, resulting in low predator consumption rate. Plant resistance only directly regulated aphid population growth on predator-excluded plants. When predators were present, plant resistance indirectly regulated herbivore population growth by changing the impact of predators on the herbivorous prey. A possible mechanism for the interaction between plant resistance and predation is that methyl salicylate, a herbivore-induced plant volatile attractive to predators, was more strongly induced in low-resistance plants. Increased plant resistance reduced predator attractant lures, preventing predators from locating their prey. Low-resistance plants may regulate herbivore populations via predators by providing reliable information on prey availability and increasing the effectiveness of predators. © 2017 The Author(s).

  9. 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.

    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

  10. Herbivore trampling as an alternative pathway for explaining differences in nitrogen mineralization in moist grasslands

    NARCIS (Netherlands)

    Schrama, Maarten; Heijning, Pieter; Bakker, Jan P.; van Wijnen, Harm J.; Berg, Matty; Olff, Han; Niklaus, Pascal

    Studies addressing the role of large herbivores on nitrogen cycling in grasslands have suggested that the direction of effects depends on soil fertility. Via selection for high quality plant species and input of dung and urine, large herbivores have been shown to speed up nitrogen cycling in fertile

  11. Jasmonate-deficient plants have reduced direct and indirect defences against herbivores

    NARCIS (Netherlands)

    Thaler, J.S.; Farag, M.A.; Paré, P.W.; Dicke, M.

    2002-01-01

    Plants employ a variety of defence mechanisms, some of which act directly by having a negative effect on herbivores and others that act indirectly by attracting natural enemies of herbivores. In this study we asked if a common jasmonate-signalling pathway links the regulation of direct and indirect

  12. Plant defense against herbivorous pests: exploiting resistance and tolerance traits for sustainable crop protection

    Directory of Open Access Journals (Sweden)

    Carolyn Mitchell

    2016-07-01

    Full Text Available Interactions between plants and insect herbivores are important determinants of plant productivity in managed and natural vegetation. In response to attack, plants have evolved a range of defenses to reduce the threat of injury and loss of productivity. Crop losses from damage caused by arthropod pests can exceed 15% annually. Crop domestication and selection for improved yield and quality can alter the defensive capability of the crop, increasing reliance on artificial crop protection. Sustainable agriculture, however, depends on reduced chemical inputs. There is an urgent need, therefore, to identify plant defensive traits for crop improvement. Plant defense can be divided into resistance and tolerance strategies. Plant traits that confer herbivore resistance typically prevent or reduce herbivore damage through expression of traits that deter pests from settling, attaching to surfaces, feeding and reproducing, or that reduce palatability. Plant tolerance of herbivory involves expression of traits that limit the negative impact of herbivore damage on productivity and yield. Identifying the defensive traits expressed by plants to deter herbivores or limit herbivore damage, and understanding the underlying defense mechanisms, is crucial for crop scientists to exploit plant defensive traits in crop breeding. In this review, we assess the traits and mechanisms underpinning herbivore resistance and tolerance, and conclude that physical defense traits, plant vigor and herbivore-induced plant volatiles show considerable utility in pest control, along with mixed species crops. We highlight emerging approaches for accelerating the identification of plant defensive traits and facilitating their deployment to improve the future sustainability of crop protection.

  13. Plant protein and secondary metabolites influence diet selection in a mammalian specialist herbivore

    Science.gov (United States)

    Amy C. Ulappa; Rick G. Kelsey; Graham G. Frye; Janet L. Rachlow; LIsa A. Shipley; Laura Bond; Xinzhu Pu; Jennifer Sorensen. Forbey

    2014-01-01

    For herbivores, nutrient intake is limited by the relatively low nutritional quality of plants and high concentrations of potentially toxic defensive compounds (plant secondary metabolites [PSMs]) produced by many plants. In response to phytochemical challenges, some herbivores selectively forage on plants with higher nutrient and lower PSM concentrations relative to...

  14. 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.

  15. Plant defenses against parasitic plants show similarities to those induced by herbivores and pathogens

    Science.gov (United States)

    Justin B. Runyon; Mark C. Mescher; Consuelo M. De Moraes

    2010-01-01

    Herbivores and pathogens come quickly to mind when one thinks of the biotic challenges faced by plants. Important but less appreciated enemies are parasitic plants, which can have important consequences for the fitness and survival of their hosts. Our knowledge of plant perception, signaling and response to herbivores and pathogens has expanded rapidly in recent years...

  16. Plant traits and plant biogeography control the biotic resistance provided by generalist herbivores

    NARCIS (Netherlands)

    Grutters, B.M.C.; Roijendijk, Yvonne; Verberk, W.C.E.P.; Bakker, E.S.

    2017-01-01

    1.Globalization and climate change trigger species invasions and range shifts, which reshuffle communities at an exceptional rate and expose plant migrants to unfamiliar herbivores. Dominant hypotheses to predict plant success are based on evolutionary novelty: either herbivores are maladapted to

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

    Science.gov (United States)

    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 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. PMID:26274491

  18. 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.

  19. Troublesome toxins: Time to re-think plant-herbivore interactions in vertebrate ecology

    Science.gov (United States)

    Swihart, R.K.; DeAngelis, D.L.; Feng, Z.; Bryant, J.P.

    2009-01-01

    Earlier models of plant-herbivore interactions relied on forms of functional response that related rates of ingestion by herbivores to mechanical or physical attributes such as bite size and rate. These models fail to predict a growing number of findings that implicate chemical toxins as important determinants of plant-herbivore dynamics. Specifically, considerable evidence suggests that toxins set upper limits on food intake for many species of herbivorous vertebrates. Herbivores feeding on toxin-containing plants must avoid saturating their detoxification systems, which often occurs before ingestion rates are limited by mechanical handling of food items. In light of the importance of plant toxins, a new approach is needed to link herbivores to their food base. We discuss necessary features of such an approach, note recent advances in herbivore functional response models that incorporate effects of plant toxins, and mention predictions that are consistent with observations in natural systems. Future ecological studies will need to address explicitly the importance of plant toxins in shaping plant and herbivore communities.

  20. 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

  1. Mechanisms and ecological consequences of plant defence induction and suppression in herbivore communities

    NARCIS (Netherlands)

    Kant, M.R.; Jonckheere, W.; Knegt, B.; Lemos, F.; Liu, J.; Schimmel, B.C.J.; Villarroel, C.A.; Ataide, L.M.S.; Dermauw, W.; Glas, J.J.; Egas, M.; Janssen, A.; Van Leeuwen, T.; Schuurink, R.C.; Sabelis, M.W.; Alba, J.M.

    2015-01-01

    BACKGROUND: Plants are hotbeds for parasites such as arthropod herbivores, which acquire nutrients and energy from their hosts in order to grow and reproduce. Hence plants are selected to evolve resistance, which in turn selects for herbivores that can cope with this resistance. To preserve their

  2. 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

  3. Effects of large herbivores on murid rodents in a South African savanna

    NARCIS (Netherlands)

    Hagenah, N.; Prins, H.H.T.; Olff, H.

    2009-01-01

    Our study presents experimentally based results on how large herbivore species affect savanna vegetation and thus murid rodents in the Hluhluwe-iMfolozi Park in KwaZulu-Natal, South Africa. We permanently excluded groups of large herbivore guilds of various body sizes (ranging from white rhino to

  4. Effects of introduction and exclusion of large herbivores on small rodent communities

    NARCIS (Netherlands)

    Smit, R.; Bokdam, J.; Ouden, den J.; Olff, H.; Schot-Opschoor, H.; Schrijvers, M.

    2001-01-01

    In this study we analysed the effects of large herbivores on small rodent communities in different habitats using large herbivore exclosures. We studied the effects of three year grazing introduction by red deer (Cervus elaphus L.) in previously ungrazed pine and oak woodland and the exclusion of

  5. Effects of large herbivores on murid rodents in a South African savanna

    NARCIS (Netherlands)

    Hagenah, Nicole; Prins, Herbert H. T.; Olff, Han

    Our study presents experimentally based results on how large herbivore species affect savanna vegetation and thus murid rodents in the Hluhluwe-iMfolozi Park in KwaZulu-Natal, South Africa. We permanently excluded groups of large herbivore guilds of various body sizes (ranging from white rhino to

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

    NARCIS (Netherlands)

    Hagenah, N.

    2006-01-01

    Keywords:African savanna, biodiversity, Dichrostachys cinerea , different-sized herbivores, fire, herbivore interactions, murid rodents, spatial heterogeneity

    Mankind has

  7. Attraction of egg-killing parasitoids toward induced plant volatiles in a multi-herbivore context

    NARCIS (Netherlands)

    Cusumano, A.; Weldegergis, B.T.; Colazza, S.; Dicke, M.; Fatouros, N.E.

    2015-01-01

    In response to insect herbivory, plants emit volatile organic compounds which may act as indirect plant defenses by attracting natural enemies of the attacking herbivore. In nature, plants are often attacked by multiple herbivores, but the majority of studies which have investigated indirect plant

  8. Plant Volatiles Induced by Herbivore Egg Deposition Affect Insects of Different Trophic Levels

    NARCIS (Netherlands)

    Fatouros, N.E.; Lucas-Barbosa, D.; Weldegergis, B.T.; Pashalidou, F.G.; Loon, van J.J.A.; Dicke, M.; Harvey, J.A.; Gols, R.; Huigens, M.E.

    2012-01-01

    Plants release volatiles induced by herbivore feeding that may affect the diversity and composition of plant-associated arthropod communities. However, the specificity and role of plant volatiles induced during the early phase of attack, i.e. egg deposition by herbivorous insects, and their

  9. Troublesome toxins: time to re-think plant-herbivore interactions in vertebrate ecology

    Science.gov (United States)

    Swihart, Robert K; DeAngelis, Donald L; Feng, Zhilan; Bryant, John P

    2009-01-01

    Earlier models of plant-herbivore interactions relied on forms of functional response that related rates of ingestion by herbivores to mechanical or physical attributes such as bite size and rate. These models fail to predict a growing number of findings that implicate chemical toxins as important determinants of plant-herbivore dynamics. Specifically, considerable evidence suggests that toxins set upper limits on food intake for many species of herbivorous vertebrates. Herbivores feeding on toxin-containing plants must avoid saturating their detoxification systems, which often occurs before ingestion rates are limited by mechanical handling of food items. In light of the importance of plant toxins, a new approach is needed to link herbivores to their food base. We discuss necessary features of such an approach, note recent advances in herbivore functional response models that incorporate effects of plant toxins, and mention predictions that are consistent with observations in natural systems. Future ecological studies will need to address explicitly the importance of plant toxins in shaping plant and herbivore communities. PMID:19239698

  10. Herbivore impact on moss depth, soil temperature and arctic plant growth

    NARCIS (Netherlands)

    van der Wal, R; Loonen, MJJE

    We provide evidence for a mechanism by which herbivores may influence plant abundance in arctic ecosystems, These systems are commonly dominated by mosses, the thickness of which influences the amount of heat reaching the soil surface. Herbivores can reduce the thickness of the moss layer by means

  11. Contrasting patterns of herbivore and predator pressure on invasive and native plants

    NARCIS (Netherlands)

    Engelkes, T.; Wouters, B.; Bezemer, T.M.; Harvey, J.A.; Van der Putten, W.H.

    2012-01-01

    Invasive non-nativeplant species often harbor fewer herbivorous insects than related nativeplant species. However, little is known about how herbivorous insects on non-nativeplants are exposed to carnivorous insects, and even less is known on plants that have recently expanded their ranges within

  12. 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

  13. Chemical ecology of host-plant selection by herbivorous arthropods : a multitrophic perspective

    NARCIS (Netherlands)

    Dicke, M.

    2000-01-01

    Most herbivorous arthropods are specialists that feed on one or a few related plant species. To understand why this is so, both mechanistic and functional studies have been carried out, predominantly restricted to bitrophic aspects. Host-selection behaviour of herbivorous arthropods has been

  14. Plant-mediated indirect effects and the persistence of parasitoid-herbivore communities

    NARCIS (Netherlands)

    Vos, M.; Berrocal, S.M.; Karamaouna, F.; Hemerik, L.; Vet, L.E.M.

    2001-01-01

    We have examined the effects of herbivore diversity on parasitoid community persistence and stability mediated by nonspecific information from herbivore-infested plants. First, we investigated host location and patch time allocation in the parasitoid Cotesia glomerata in environments where host

  15. Plant-mediated indirect effects and the persistence of parasitoid-herbivore communities

    NARCIS (Netherlands)

    Vos, M.; Berrocal, S.M.; Karamaouna, F.; Hemerik, L.; Vet, L.E.M.

    2001-01-01

    We have examined the effects of herbivore diversity on parasitoid community persistence and stability, mediated by nonspecific information from herbivore-infested plants. First, we investigated host location and patch time allocation in the parasitoid Cotesia glomerata in environments where host

  16. Indirect defence of plants against herbivores: using Arabidopsis thaliana as a model plant

    NARCIS (Netherlands)

    Poecke, van R.M.P.; Dicke, M.

    2004-01-01

    In their defence against pathogens, herbivorous insects, and mites, plants employ many induced responses. One of these responses is the induced emission of volatiles upon herbivory. These volatiles can guide predators or parasitoids to their herbivorous prey, and thus benefit both plant and

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

    Science.gov (United States)

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

    2015-01-01

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

  18. Aboveground vertebrate and invertebrate herbivore impact on net N mineralization in subalpine grasslands : Ecology

    NARCIS (Netherlands)

    Risch, Anita C.; Schütz, 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

    2015-01-01

    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

  19. Aboveground vertebrate and invertebrate herbivore impact on net N mineralization in subalpine grasslands

    NARCIS (Netherlands)

    Risch, A.C.; Schütz, Martin; Vandegehuchte, Martijn L.; Putten, Van Der W.H.; Duyts, Henk; Raschein, Ursina; Gwiazdowicz, D.J.; Busse, M.D.; Page-Dumroese, D.S.; Zimmermann, Stephan

    2015-01-01

    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

  20. Can Bt Technology Reduce Poverty Among African Cotton Growers? An Ex Ante Analysis of the Private and Social Profitability of Bt Cotton Seed in Mozambique.

    OpenAIRE

    Pitoro, Raul; Walker, Thomas S.; Tschirley, David L.; Swinton, Scott M.; Boughton, Duncan; de Marrule, Higino Francisco

    2009-01-01

    This paper presents an ex ante analysis of the private and social profitability of the introduction of Bt cotton for a major cotton producing area of northern Mozambique. Cotton is especially relevant to rural poverty reduction because smallholders often have few alternative cash earning activities, and yields are among the lowest in Africa. Multivariate regression is used to quantify the relationship between pest control and yield loss at farm level as a basis for estimating the expected yie...

  1. Adaptive divergence in resistance to herbivores in Datura stramonium

    Directory of Open Access Journals (Sweden)

    Guillermo Castillo

    2015-11-01

    Full Text Available Defensive traits exhibited by plants vary widely across populations. Heritable phenotypic differentiation is likely to be produced by genetic drift and spatially restricted gene flow between populations. However, spatially variable selection exerted by herbivores may also give rise to differences among populations. To explore to what extent these factors promote the among-population differentiation of plant resistance of 13 populations of Datura stramonium, we compared the degree of phenotypic differentiation (PST of leaf resistance traits (trichome density, atropine and scopolamine concentration against neutral genetic differentiation (FST at microsatellite loci. Results showed that phenotypic differentiation in defensive traits among-population is not consistent with divergence promoted by genetic drift and restricted gene flow alone. Phenotypic differentiation in scopolamine concentration was significantly higher than FST across the range of trait heritability values. In contrast, genetic differentiation in trichome density was different from FST only when heritability was very low. On the other hand, differentiation in atropine concentration differed from the neutral expectation when heritability was less than or equal to 0.3. In addition, we did not find a significant correlation between pair-wise neutral genetic distances and distances of phenotypic resistance traits. Our findings reinforce previous evidence that divergent natural selection exerted by herbivores has promoted the among-population phenotypic differentiation of defensive traits in D. stramonium.

  2. Adaptive divergence in resistance to herbivores in Datura stramonium.

    Science.gov (United States)

    Castillo, Guillermo; Valverde, Pedro L; Cruz, Laura L; Hernández-Cumplido, Johnattan; Andraca-Gómez, Guadalupe; Fornoni, Juan; Sandoval-Castellanos, Edson; Olmedo-Vicente, Erika; Flores-Ortiz, César M; Núñez-Farfán, Juan

    2015-01-01

    Defensive traits exhibited by plants vary widely across populations. Heritable phenotypic differentiation is likely to be produced by genetic drift and spatially restricted gene flow between populations. However, spatially variable selection exerted by herbivores may also give rise to differences among populations. To explore to what extent these factors promote the among-population differentiation of plant resistance of 13 populations of Datura stramonium, we compared the degree of phenotypic differentiation (P ST) of leaf resistance traits (trichome density, atropine and scopolamine concentration) against neutral genetic differentiation (F ST) at microsatellite loci. Results showed that phenotypic differentiation in defensive traits among-population is not consistent with divergence promoted by genetic drift and restricted gene flow alone. Phenotypic differentiation in scopolamine concentration was significantly higher than F ST across the range of trait heritability values. In contrast, genetic differentiation in trichome density was different from F ST only when heritability was very low. On the other hand, differentiation in atropine concentration differed from the neutral expectation when heritability was less than or equal to 0.3. In addition, we did not find a significant correlation between pair-wise neutral genetic distances and distances of phenotypic resistance traits. Our findings reinforce previous evidence that divergent natural selection exerted by herbivores has promoted the among-population phenotypic differentiation of defensive traits in D. stramonium.

  3. 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.

  4. Confounded winter and spring phenoclimatology on large herbivore ranges

    Science.gov (United States)

    Christianson, David; Klaver, Robert W.; Middleton, Arthur; Kauffman, Matthew

    2013-01-01

    Annual variation in winter severity and growing season vegetation dynamics appear to influence the demography of temperate herbivores but parsing winter from spring effects requires independent metrics of environmental conditions specific to each season. We tested for independence in annual variation amongst four common metrics used to describe winter severity and early growing season vegetation dynamics across the entire spatial distribution of elk (Cervus elaphus) in Wyoming from 1989 to 2006. Winter conditions and early growing season dynamics were correlated in a specific way. Winters with snow cover that ended early tended to be followed by early, but slow, rises in the normalized difference vegetation index (NDVI), while long winters with extended periods of snow cover were often followed by late and rapid rises in NDVI. Across the 35 elk ranges, 0.4–86.8 % of the variation in the rate of increase in NDVI’s in spring was explained by the date snow cover disappeared from SNOTEL stations. Because phenoclimatological metrics are correlated across seasons and shifting due to climate change, identifying environmental constraints on herbivore fitness, particularly migratory species, is more difficult than previously recognized.

  5. 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

  6. Bacillus thuringiensis (Bt for the Control of Insect Pests in Stored Tobacco: A Review

    Directory of Open Access Journals (Sweden)

    Blanc M

    2014-12-01

    Full Text Available Among the insect species causing infestations and serious damages to stored commodities, the cigarette beetle, Lasiodermaserricorne (F. and the tobacco moth, Ephestiaelutella (Hübner are the major pests of both raw and manufactured tobacco. Post-harvest tobacco control is achieved through sanitation, insect monitoring, and fumigation with phosphine. However, insect resistance to phosphine and control failures have been reported, and increasing regulatory pressure is being exerted on fumigants. Biological control agents such as Bacillus thuringiensis (Bt appear to be environmentally sound and potentially viable alternatives to chemical control. Bt is a bacterium that produces insecticidal crystal proteins during the sporulation phase and has been, for more than 40 years, the microorganism of choice for the biocontrol of phytophagous insect pests. It produces insecticidal crystal proteins that display specific activity against certain orders of insects and become active upon ingestion by the insect. Our laboratory has conducted extensive research and worldwide surveys to evaluate the presence of Bt in stored tobacco and has confirmed previous findings indicating that Bt may be considered part of the naturally occurring phylloplanemicroflora. Several Bt strains were isolated from tobacco and characterized by DNA and protein profiling. The insecticidal activity of selected strains and of two commercial products against the larvae of L. serricorne was determined by diet incorporation assays. Moreover, the stability of Bt spores and crystal proteins on cured tobacco leaves was assessed over a storage period of time of 30 months. Cigarette prototypes were made with Bt-treated tobacco. Standard cigarette and smoke evaluations did not show any significant difference between the test and control cigarettes. Although the tested Bt strains and products did not yield satisfactory levels of mortality at the required times and doses, the experimental results

  7. 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...

  8. Are cattle surrogate wildlife? Savanna plant community composition explained by total herbivory more than herbivore type.

    Science.gov (United States)

    Veblen, Kari E; Porensky, Lauren M; Riginos, Corinna; Young, Truman P

    2016-09-01

    The widespread 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 can have important implications for plant community dynamics. Yet very few studies have experimentally addressed the individual, combined, and potentially interactive effects of wild vs. domestic herbivore species on herbaceous plant communities within a single system. Additionally, there is little information about whether, and in which contexts, livestock might functionally replace native herbivore wildlife or, alternatively, have fundamentally different effects on plant species composition. The Kenya Long-term Exclosure Experiment, which has been running since 1995, is composed of six treatment combinations of mega-herbivores, meso-herbivore ungulate wildlife, and cattle. We sampled herbaceous vegetation 25 times between 1999 and 2013. We used partial redundancy analysis and linear mixed models to assess effects of herbivore treatments on overall plant community composition and key plant species. Plant communities in the six different herbivore treatments shifted directionally over time and diverged from each other substantially by 2013. Plant community composition was strongly related (R2  = 0.92) to residual plant biomass, a measure of herbivore utilization. Addition of any single herbivore type (cattle, wildlife, or mega-herbivores) caused a shift in plant community composition that was proportional to its removal of plant biomass. These results suggest that overall herbivory pressure, rather than herbivore type or complex interactions among different herbivore types, was the main driver of changes in plant community composition. Individual plant species, however, did respond most strongly to either wild ungulates or cattle. Although these results suggest considerable functional similarity between

  9. Overexpression of the Bacillus thuringiensis (Bt) Cry2Aa2 protein in chloroplasts confers resistance to plants against susceptible and Bt-resistant insects.

    Science.gov (United States)

    Kota, M; Daniell, H; Varma, S; Garczynski, S F; Gould, F; Moar, W J

    1999-03-02

    Evolving levels of resistance in insects to the bioinsecticide Bacillus thuringiensis (Bt) can be dramatically reduced through the genetic engineering of chloroplasts in plants. When transgenic tobacco leaves expressing Cry2Aa2 protoxin in chloroplasts were fed to susceptible, Cry1A-resistant (20,000- to 40,000-fold) and Cry2Aa2-resistant (330- to 393-fold) tobacco budworm Heliothis virescens, cotton bollworm Helicoverpa zea, and the beet armyworm Spodoptera exigua, 100% mortality was observed against all insect species and strains. Cry2Aa2 was chosen for this study because of its toxicity to many economically important insect pests, relatively low levels of cross-resistance against Cry1A-resistant insects, and its expression as a protoxin instead of a toxin because of its relatively small size (65 kDa). Southern blot analysis confirmed stable integration of cry2Aa2 into all of the chloroplast genomes (5, 000-10,000 copies per cell) of transgenic plants. Transformed tobacco leaves expressed Cry2Aa2 protoxin at levels between 2% and 3% of total soluble protein, 20- to 30-fold higher levels than current commercial nuclear transgenic plants. These results suggest that plants expressing high levels of a nonhomologous Bt protein should be able to overcome or at the very least, significantly delay, broad spectrum Bt-resistance development in the field.

  10. Chemical and molecular ecology of herbivore-induced plant volatiles: proximate factors and their ultimate functions.

    Science.gov (United States)

    Arimura, Gen-Ichiro; Matsui, Kenji; Takabayashi, Junji

    2009-05-01

    In response to herbivory, plants emit specific blends of herbivore-induced plant volatiles (HIPVs). HIPVs mediate sizable arrays of interactions between plants and arthropods, microorganisms, undamaged neighboring plants or undamaged sites within the plant in various ecosystems. HIPV profiles vary according to the plant and herbivore species, and the developmental stages and conditions of the live plants and herbivores. To understand the regulatory mechanisms underling HIPV biosynthesis, the following issues are reviewed here: (i) herbivore-induced formation of plant volatile terpenoids and green leaf volatiles; (ii) initial activation of plant responses by feeding herbivores; and (iii) the downstream network of the signal transduction. To understand the ecological significance of HIPVs, we also review case studies of insect-plant and inter-/intraplant interactions mediated by HIPVs that have been documented in the field and laboratory in recent years.

  11. 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.

  12. Recent advances in plant-herbivore interactions [version 1; referees: 2 approved

    Directory of Open Access Journals (Sweden)

    Deron E. Burkepile

    2017-02-01

    Full Text Available Plant-herbivore interactions shape community dynamics across marine, freshwater, and terrestrial habitats. From amphipods to elephants and from algae to trees, plant-herbivore relationships are the crucial link generating animal biomass (and human societies from mere sunlight. These interactions are, thus, pivotal to understanding the ecology and evolution of virtually any ecosystem. Here, we briefly highlight recent advances in four areas of plant-herbivore interactions: (1 plant defense theory, (2 herbivore diversity and ecosystem function, (3 predation risk aversion and herbivory, and (4 how a changing climate impacts plant-herbivore interactions. Recent advances in plant defense theory, for example, highlight how plant life history and defense traits affect and are affected by multiple drivers, including enemy pressure, resource availability, and the local plant neighborhood, resulting in trait-mediated feedback loops linking trophic interactions with ecosystem nutrient dynamics. Similarly, although the positive effect of consumer diversity on ecosystem function has long been recognized, recent advances using DNA barcoding to elucidate diet, and Global Positioning System/remote sensing to determine habitat selection and impact, have shown that herbivore communities are probably even more functionally diverse than currently realized. Moreover, although most diversity-function studies continue to emphasize plant diversity, herbivore diversity may have even stronger impacts on ecosystem multifunctionality. Recent studies also highlight the role of risk in plant-herbivore interactions, and risk-driven trophic cascades have emerged as landscape-scale patterns in a variety of ecosystems. Perhaps not surprisingly, many plant-herbivore interactions are currently being altered by climate change, which affects plant growth rates and resource allocation, expression of chemical defenses, plant phenology, and herbivore metabolism and behavior. Finally

  13. Information use by the predatory mite Phytoseiulus persimilis (Acari: Phytoseiidae), a specialised natural enemy of herbivorous spider mites

    NARCIS (Netherlands)

    Boer, de J.G.; Dicke, M.

    2005-01-01

    Plants can respond to infestation by herbivores with the emission of specific herbivore-induced plant volatiles. Many carnivorous arthropods that feed on herbivorous prey use these volatiles to locate their prey. Despite the growing amount of research papers on the interactions in tritrophic

  14. Interactions between large herbivores and litter removal by termites across a rainfall gradient in a South African savanna

    CSIR Research Space (South Africa)

    Buitenwerf, R

    2011-05-01

    Full Text Available : litter removal by termites was greater in the presence of large herbivores at the drier sites but lower in the presence of large herbivores at the wetter sites. The effect of herbivores on termite foraging intensity may indicate a switch between termites...

  15. 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…

  16. Field assessment of Bt cry1Ah corn pollen on the survival, development and behavior of Apis mellifera ligustica.

    Science.gov (United States)

    Dai, Ping-Li; Zhou, Wei; Zhang, Jie; Cui, Hong-Juan; Wang, Qiang; Jiang, Wei-Yu; Sun, Ji-Hu; Wu, Yan-Yan; Zhou, Ting

    2012-05-01

    Honeybees may be exposed to insecticidal proteins from transgenic plants via pollen. An assessment of the impact of such exposures on the honeybee is an essential part of the risk assessment process for transgenic Bacillus thuringiensis corn. A field trial was conducted to evaluate the effect of transgenic Bt cry1Ah corn on the honeybee Apis mellifera ligustica. Colonies of honeybees were moved to Bt or non-Bt corn fields during anthesis and then sampled to record their survival, development and behavior. No differences in immature stages, worker survival, bee body weight, hypopharyngeal gland weight, colony performance, foraging activity or olfactory learning abilities were detected between colonies that were placed in non-Bt corn fields and those placed in Bt corn fields. We conclude that cry1Ah corn carries no risk for the survival, development, colony performance or behavior of the honeybee A. mellifera ligustica. Copyright © 2012 Elsevier Inc. All rights reserved.

  17. 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

  18. Impacts of transgenic poplar-cotton agro-ecosystems upon target pests and non-target insects under field conditions.

    Science.gov (United States)

    Zhang, D J; Liu, J X; Lu, Z Y; Li, C L; Comada, E; Yang, M S

    2015-07-27

    Poplar-cotton agro-ecosystems are the main agricultural planting modes of cotton fields in China. With increasing acres devoted to transgenic insect-resistant poplar and transgenic insect-resistant cotton, studies examining the effects of transgenic plants on target and non-target insects become increasingly important. We systematically surveyed populations of both target pests and non-target insects for 4 different combinations of poplar-cotton eco-systems over 3 years. Transgenic Bt cotton strongly resisted the target insects Fall webworm moth [Hyphantria cunea (Drury)], Sylepta derogata Fabrieius, and American bollworm (Heliothis armigera), but no clear impact on non-target insect cotton aphids (Aphis gossypii). Importantly, intercrops containing transgenic Pb29 poplar significantly increased the inhibitory effects of Bt cotton on Fall webworm moth in ecosystem IV. Highly resistant Pb29 poplar reduced populations of the target pests Grnsonoma minutara Hubner and non-target insect poplar leaf aphid (Chaitophorus po-pulialbae), while Fall webworm moth populations were unaffected. We determined the effects of Bt toxin from transgenic poplar and cotton on target and non-target pests in different ecosystems of cotton-poplar intercrops and identified the synergistic effects of such combinations toward both target and non-target insects.

  19. A Study of the Use of the "TOEFL iBT"® Test Speaking and Listening Scores for International Teaching Assistant Screening. "TOEFL iBT"® Research Report. TOEFL iBT-27. ETS Research Report. RR-16-18

    Science.gov (United States)

    Wagner, Elvis

    2016-01-01

    Although the speaking section of the "TOEFL iBT"® test is used by many universities to determine if international teaching assistants (ITAs) have the oral proficiency necessary to be classroom instructors, relatively few studies have investigated the validity of using TOEFL iBT scores for ITA screening. The primary purpose of this study…

  20. Isolation of a novel uric-acid-degrading microbe Comamonas sp. BT ...

    Indian Academy of Sciences (India)

    2014-10-20

    Oct 20, 2014 ... blood samples by the biosensor and satisfactory results were obtained. [Ghosh T and Sarkar P 2014 Isolation of a novel uric-acid-degrading microbe Comamonas sp. BT UA and rapid biosensing of uric acid from extracted uricase enzyme. J. Biosci. 39 805–819] DOI 10.1007/s12038-014-9476-2. 1.

  1. The Utility of the Lambert Function W[a exp(a - bt)] in Chemical Kinetics

    Science.gov (United States)

    Williams, Brian Wesley

    2010-01-01

    The mathematical Lambert function W[a exp(a - bt)] is used to find integrated rate laws for several examples, including simple enzyme and Lindemann-Christiansen-Hinshelwood (LCH) unimolecular decay kinetics. The results derived here for the well-known LCH mechanism as well as for a dimer-monomer reaction mechanism appear to be novel. A nonlinear…

  2. 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...

  3. 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

  4. 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.

  5. Reduced fitness of Daphnia magna fed a Bt-transgenic maize variety.

    Science.gov (United States)

    Bøhn, Thomas; Primicerio, Raul; Hessen, Dag O; Traavik, Terje

    2008-11-01

    Genetically modified (GM) maize expressing the Bt-toxin Cry1Ab (Bt-maize) was tested for effects on survival, growth, and reproduction of the water flea Daphnia magna, a crustacean arthropod commonly used as a model organism in ecotoxicological studies. In three repeated experiments, D. magna were fed 100% ground maize in suspension, using either GM or isogenic unmodified (UM) maize. D. magna fed GM-maize showed a significantly reduced fitness performance: The mortality was higher, a lower proportion of females reached sexual maturation, and the overall egg production was lower compared to D. magna fed UM isogenic maize. We conclude that the tested variety of Bt-maize and its UM counterpart do not have the same quality as food sources for this widely used model organism. The combination of a reduced fitness performance combined with earlier onset of reproduction of D. magna fed Bt-maize indicates a toxic effect rather than a lower nutritional value of the GM-maize.

  6. Insect oviposition behavior affects the evolution of adaptation to Bt crops: consequences for refuge policies

    NARCIS (Netherlands)

    Jongsma, M.A.; Gould, F.; Legros, M.; Yang, L.; Loon, van J.J.A.; Dicke, M.

    2010-01-01

    The major lepidopteran insect pests of cotton and maize harbor intra-specific variation for behavior determining the selection of host plants for oviposition. Yet, the consequences of behavioral adaptation for fitness have neither been modeled nor monitored for Bt cotton and maize crops, the most

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

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    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.

  8. Canadian user perspectives on Bt use for protection against spruce budworm

    Science.gov (United States)

    H. J. Irving

    1985-01-01

    Reference is made to a recent interprovincial review of the performance of present day B.t. viz a viz conventional chemicals. The argument is presented that in the Canadian context its practical acceptability to resource managers remains highly jurisdictionally-specific for reasons over and above conventional technical assessments. The New Brunswick situation is...

  9. FORMING OF MECHANICAL CHARACTERISTICS OF THE SLUGS OF TITANIC ALLOY BT23 AT THERMAL TREATMENT

    Directory of Open Access Journals (Sweden)

    V. N. Fedulov

    2005-01-01

    Full Text Available Тhе changings of the initial plate structure of alloy BT23 at running of high-temperature thermal treatment of large-sized slugs with heating up to 650- 950 eC and cooling on air and in water and their influence on forming of complex of mechanical characteristics are examined.

  10. 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…

  11. 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…

  12. Construct Validity in TOEFL iBT Speaking Tasks: Insights from Natural Language Processing

    Science.gov (United States)

    Kyle, Kristopher; Crossley, Scott A.; McNamara, Danielle S.

    2016-01-01

    This study explores the construct validity of speaking tasks included in the TOEFL iBT (e.g., integrated and independent speaking tasks). Specifically, advanced natural language processing (NLP) tools, MANOVA difference statistics, and discriminant function analyses (DFA) are used to assess the degree to which and in what ways responses to these…

  13. 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…

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

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    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.

  15. Herbivore Biodiversity Varies with Patch Size in an Urban Archipelago

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    Robert F. Bode

    2014-01-01

    Full Text Available The effects of ecosystem fragmentation on biodiversity during urbanization are well established. As a city grows, it replaces much of the native plant life with asphalt, cement, and lawns, yet small patches of native plants remain in greenspaces, which act as refugia for native animals. However, little work has been done on the patterns of re-colonization by native animals as urban decay allows for re-establishment of native plant communities. We found that patterns of biodiversity in the insect herbivore community within an archipelago of abandoned lots follow patterns of island biogeography, with higher biodiversity on large islands. We also found that insect colonization of the abandoned lots was correlated with each species' dispersal ability. The patterns seen here have implications for patterns of species movement into urban systems as new parks are established or as abandoned lots are re-colonized by native plants.

  16. Aquatic herbivores facilitate the emission of methane from wetlands.

    Science.gov (United States)

    Dingemans, Bas J J; Bakker, Elisabeth S; Bodelier, Paul L E

    2011-05-01

    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 vegetation and over single shoots. Both methods showed significantly higher methane release from grazed vegetation. Surface-based diffusive methane emission from grazed plots was up to five times higher compared to exclosures. The absence of an effect on methane-cycling microbial processes indicated that this modulating effect acts on the gas transport by the plants. Modulation of methane emission by animal-plant-microbe interactions deserves further attention considering the increasing bird populations and changes in wetland vegetation as a consequence of changing land use and climate change.

  17. 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

  18. What are farmers really planting? Measuring the presence and effectiveness of Bt cotton in Pakistan.

    Directory of Open Access Journals (Sweden)

    David J Spielman

    Full Text Available Genetically modified, insect-resistant Bacillus thuringiensis (Bt cotton is cultivated extensively in Pakistan. Past studies, however, have raised concerns about the prevalence of Bt cotton varieties possessing weak or nonperforming insect-resistance traits conferred by the cry gene. We examine this issue using data drawn from a representative sample of cotton-growing households that were surveyed in six agroclimatic zones spanning 28 districts in Pakistan in 2013, as well as measurements of Cry protein levels in cotton tissue samples collected from the sampled households' main fields. The resultant dataset combines information from 593 sampled households with corresponding plant tissue diagnostics from 70 days after sowing, as well as information from 589 sampled households with corresponding diagnostics from 120 days after sowing. Our analysis indicates that 11 percent of farmers believed they were cultivating Bt cotton when, in fact, the Cry toxin was not present in the tested tissue at 70 days after sowing (i.e., a Type I error. The analysis further indicates that 5 percent of farmers believed they were cultivating non-Bt cotton when, in fact, the Cry toxin was present in the tested tissue (i.e., a Type II error. In addition, 17 percent of all sampled farmers were uncertain whether or not they were cultivating Bt cotton. Overall, 33 percent of farmers either did not know or were mistaken in their beliefs about the presence of the cry gene in the cotton they cultivated. Results also indicate that toxic protein levels in the plant tissue samples occurred below threshold levels for lethality in a significant percentage of cases, although these measurements may also be affected by factors related to tissue sample collection, handling, storage, and testing procedures. Nonetheless, results strongly suggest wide variability both in farmers' beliefs and in gene expression. Such variability has implications for policy and regulation in Pakistan

  19. Genetic diversity analysis of Bt cotton genotypes in Pakistan using simple sequence repeat markers.

    Science.gov (United States)

    Ullah, I; Iram, A; Iqbal, M Z; Nawaz, M; Hasni, S M; Jamil, S

    2012-03-14

    The popularity of genetically modified insect resistant (Bt) cotton has promoted large scale monocultures, which is thought to worsen the problem of crop genetic homogeneity. Information on genetic diversity among Bt cotton varieties is lacking. We evaluated genetic divergence among 19 Bt cotton genotypes using simple sequence repeat (SSR) markers. Thirty-seven of 104 surveyed primers were found informative. Fifty-two primers selected on the basis of reported intra-hirsutum polymorphism in a cotton marker database showed a high degree of polymorphism, 56% compared to 13% for randomly selected primers. A total of 177 loci were amplified, with an average of 1.57 loci per primer, generating 38 markers. The amplicons ranged in size from 98 to 256 bp. The genetic similarities among the 19 genotypes ranged from 0.902 to 0.982, with an average of 0.947, revealing a lack of diversity. Similarities among genotypes from public sector organizations were higher than genotypes developed by private companies. Hybrids were found to be more distant compared to commercial cultivars and advanced breeding lines. Cluster analysis grouped the 19 Bt cotton genotypes into three major clusters and two independent entries. Cultivars IR-3701, Ali Akbar-802 and advanced breeding line VH-259 grouped in subcluster B2, with very narrow genetic distances despite dissimilar parentage. We found a very high level of similarity among Pakistani-bred Bt cotton varieties, which means that genetically diverse recurrent parents should be included to enhance genetic diversity. The intra-hirsutum polymorphic SSRs were found to be highly informative for molecular genetic diversity studies in these cotton varieties.

  20. Herbivores increase the global availability of nutrients over millions of years.

    Science.gov (United States)

    Doughty, Christopher E

    2017-12-01

    Can the presence of herbivores increase global nutrient availability? Animals disperse vital nutrients through ecosystems, increasing the spatial availability of these nutrients. Large herbivores are especially important for the dispersal of vital nutrients due to their long food passage times and day ranges, and large herbivores from past periods (the Pleistocene) may have increased nutrient concentrations on the continental scale. However, such results have been demonstrated theoretically but not yet empirically. Models suggest that the Pennsylvanian subperiod (323-299 million years ago), with no tetrapod terrestrial herbivores, would have had fewer, less-well-distributed nutrients than the Cretaceous period (145-66 million years ago), with the largest terrestrial herbivores ever-the sauropods. Here, I show that these models are supported empirically by remnant plant material (coal deposits) from the Cretaceous (N = 680), which had significantly (P < 0.00001) increased concentrations (136%) and decreased spatial heterogeneity (22%) of plant-important rock-derived nutrients compared with the Pennsylvanian subperiod (N = 4,996). Non-biotic physical processes, such as weathering rates, cannot account for such differences, because aluminium-a nutrient not important for plants and animals, but weathered in a similar manner to the above elements-showed no significant difference between the two periods, suggesting that these large changes were driven by plant-herbivore interactions. Populations of large wild herbivores are currently at historical lows; therefore, we are potentially losing a key ecosystem service.

  1. Evolution of specialization and ecological character displacement of herbivores along a gradient of plant quality.

    Science.gov (United States)

    Egas, Martijn; Sabelis, Maurice W; Dieckmann, Ulf

    2005-03-01

    We study the combined evolutionary dynamics of herbivore specialization and ecological character displacement, taking into account foraging behavior of the herbivores, and a quality gradient of plant types. Herbivores can adapt by changing two adaptive traits: their level of specialization in feeding efficiency and their point of maximum feeding efficiency along the plant gradient. The number of herbivore phenotypes, their levels of specialization, and the amount of character displacement among them are the result of the evolutionary dynamics, which is driven by the underlying population dynamics, which in turn is driven by the underlying foraging behavior. Our analysis demonstrates broad conditions for the diversification of a herbivore population into many specialized phenotypes, for basically any foraging behavior focusing use on highest gains while also including errors. Our model predicts two characteristic phases in the adaptation of herbivore phenotypes: a fast character-displacement phase and a slow coevolutionary niche-shift phase. This two-phase pattern is expected to be of wide relevance in various consumer-resource systems. Bringing together ecological character displacement and the evolution of specialization in a single model, our study suggests that the foraging behavior of herbivorous arthropods is a key factor promoting specialist radiation.

  2. Selection mosaic exerted by specialist and generalist herbivores on chemical and physical defense of Datura stramonium.

    Directory of Open Access Journals (Sweden)

    Guillermo Castillo

    Full Text Available Selection exerted by herbivores is a major force driving the evolution of plant defensive characters such as leaf trichomes or secondary metabolites. However, plant defense expression is highly variable among populations and identifying the sources of this variation remains a major challenge. Plant populations are often distributed across broad geographic ranges and are exposed to different herbivore communities, ranging from generalists (that feed on diverse plant species to specialists (that feed on a restricted group of plants. We studied eight populations of the plant Datura stramonium usually eaten by specialist or generalist herbivores, in order to examine whether the pattern of phenotypic selection on secondary compounds (atropine and scopolamine and a physical defense (trichome density can explain geographic variation in these traits. Following co-evolutionary theory, we evaluated whether a more derived alkaloid (scopolamine confers higher fitness benefits than its precursor (atropine, and whether this effect differs between specialist and generalist herbivores. Our results showed consistent directional selection in almost all populations and herbivores to reduce the concentration of atropine. The most derived alkaloid (scopolamine was favored in only one of the populations, which is dominated by a generalist herbivore. In general, the patterns of selection support the existence of a selection mosaic and accounts for the positive correlation observed between atropine concentration and plant damage by herbivores recorded in previous studies.

  3. Selection mosaic exerted by specialist and generalist herbivores on chemical and physical defense of Datura stramonium.

    Science.gov (United States)

    Castillo, Guillermo; Cruz, Laura L; Tapia-López, Rosalinda; Olmedo-Vicente, Erika; Olmedo-Vicente, Eika; Carmona, Diego; Anaya-Lang, Ana Luisa; Fornoni, Juan; Andraca-Gómez, Guadalupe; Valverde, Pedro L; Núñez-Farfán, Juan

    2014-01-01

    Selection exerted by herbivores is a major force driving the evolution of plant defensive characters such as leaf trichomes or secondary metabolites. However, plant defense expression is highly variable among populations and identifying the sources of this variation remains a major challenge. Plant populations are often distributed across broad geographic ranges and are exposed to different herbivore communities, ranging from generalists (that feed on diverse plant species) to specialists (that feed on a restricted group of plants). We studied eight populations of the plant Datura stramonium usually eaten by specialist or generalist herbivores, in order to examine whether the pattern of phenotypic selection on secondary compounds (atropine and scopolamine) and a physical defense (trichome density) can explain geographic variation in these traits. Following co-evolutionary theory, we evaluated whether a more derived alkaloid (scopolamine) confers higher fitness benefits than its precursor (atropine), and whether this effect differs between specialist and generalist herbivores. Our results showed consistent directional selection in almost all populations and herbivores to reduce the concentration of atropine. The most derived alkaloid (scopolamine) was favored in only one of the populations, which is dominated by a generalist herbivore. In general, the patterns of selection support the existence of a selection mosaic and accounts for the positive correlation observed between atropine concentration and plant damage by herbivores recorded in previous studies.

  4. Synergistic effects of amides from two piper species on generalist and specialist herbivores.

    Science.gov (United States)

    Richards, Lora A; Dyer, Lee A; Smilanich, Angela M; Dodson, Craig D

    2010-10-01

    Plants use a diverse mix of defenses against herbivores, including multiple secondary metabolites, which often affect herbivores synergistically. Chemical defenses also can affect natural enemies of herbivores via limiting herbivore populations or by affecting herbivore resistance to parasitoids. In this study, we performed feeding experiments to examine the synergistic effects of imides and amides (hereafter "amides") from Piper cenocladum and P. imperiale on specialist (Eois nympha, Geometridae) and generalist (Spodoptera frugiperda, Noctuidae) lepidopteran larvae. Each Piper species has three unique amides, and in each experiment, larvae were fed diets containing different concentrations of single amides or combinations of the three. The amides from P. imperiale had negative synergistic effects on generalist survival and specialist pupal mass, but had no effect on specialist survival. Piper cenocladum amides also acted synergistically to increase mortality caused by parasitoids, and the direct negative effects of mixtures on parasitoid resistance and pupal mass were stronger than indirect effects via changes in growth rate and approximate digestibility. Our results are consistent with plant defense theory that predicts different effects of plant chemistry on generalist versus adapted specialist herbivores. The toxicity of Piper amide mixtures to generalist herbivores are standard bottom-up effects, while specialists experienced the top-down mediated effect of mixtures causing reduced parasitoid resistance and associated decreases in pupal mass.

  5. 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.

  6. Indirect effects of domestic and wild herbivores on butterflies in an African savanna

    Science.gov (United States)

    Wilkerson, Marit L; Roche, Leslie M; Young, Truman P

    2013-01-01

    Indirect interactions driven by livestock and wild herbivores are increasingly recognized as important aspects of community dynamics in savannas and rangelands. Large ungulate herbivores can both directly and indirectly impact the reproductive structures of plants, which in turn can affect the pollinators of those plants. We examined how wild herbivores and cattle each indirectly affect the abundance of a common pollinator butterfly taxon, Colotis spp., at a set of long-term, large herbivore exclosure plots in a semiarid savanna in central Kenya. We also examined effects of herbivore exclusion on the main food plant of Colotis spp., which was also the most common flowering species in our plots: the shrub Cadaba farinosa. The study was conducted in four types of experimental plots: cattle-only, wildlife-only, cattle and wildlife (all large herbivores), and no large herbivores. Across all plots, Colotis spp. abundances were positively correlated with both Cadaba flower numbers (adult food resources) and total Cadaba canopy area (larval food resources). Structural equation modeling (SEM) revealed that floral resources drove the abundance of Colotis butterflies. Excluding browsing wildlife increased the abundances of both Cadaba flowers and Colotis butterflies. However, flower numbers and Colotis spp. abundances were greater in plots with cattle herbivory than in plots that excluded all large herbivores. Our results suggest that wild browsing herbivores can suppress pollinator species whereas well-managed cattle use may benefit important pollinators and the plants that depend on them. This study documents a novel set of ecological interactions that demonstrate how both conservation and livelihood goals can be met in a working landscape with abundant wildlife and livestock. PMID:24198932

  7. Plant-herbivore interactions along elevational gradient: Comparison of field and common garden data

    Science.gov (United States)

    Rokaya, Maan Bahadur; Dostálek, Tomáš; Münzbergová, Zuzana

    2016-11-01

    In response to climate change, various organisms tend to migrate to higher elevations and latitudes. Unequal migration rates of plants and animals are expected to result in changes in the type and intensity of their interactions such as plant-herbivore interactions. In the present study, we studied the extent of herbivore damage in Salvia nubicola along an elevational gradient in Manang, central Nepal. A common garden experiment was also carried out by sowing seeds collected from different populations along the elevational gradient. As expected, the extent of herbivore damage in the field was significantly lower at higher elevations, and it increased with the population size and at sites without shrubs. In the common garden experiment, herbivore damage was higher in plants originating from lower elevations and from more open habitats. While higher herbivore pressure in the field at lower elevations may suggest that plants will be better protected against herbivores at lower elevations, the common garden study demonstrated the opposite. A possible explanation could be that plants from higher elevations have to adapt to extreme conditions, and lower palatability is a side effect of these adaptations. Thus, S. nubicola in the Himalayan region is likely to survive the expected higher herbivore pressure caused by an upward shift of herbivores under future climate change. Future studies should attempt to elucidate generality of such a conclusion by studying multiple species along similar gradients. Our results from comparison of the field and common garden study suggest that future experiments need to include comparisons in common environments to understand the expected response of plants to changes in herbivore pressure.

  8. Bilingual Education in Brunei: The Evolution of the Brunei Approach to Bilingual Education and the Role of CfBT in Promoting Educational Change. Full Report

    Science.gov (United States)

    Sammons, Pamela; Davis, Susila; Bakkum, Linda; Hessel, Gianna

    2014-01-01

    During 2012/13, academics from the Department of Education, University of Oxford were commissioned by CfBT to conduct an independent evaluation of the CfBT Brunei English teaching programme. This report describes the main findings from a research project that studied the role of CfBT Education Trust in supporting improved English language teaching…

  9. Efficacy of genetically modified Bt toxins alone and in combinations against pink bollworm resistant to Cry1Ac and Cry2Ab

    Science.gov (United States)

    Evolution of resistance in pests threatens the long-term success of transgenic crops that produce insecticidal proteins from Bacillus thuringiensis (Bt). Previous work showed that genetically modified Bt toxins Cry1AbMod and Cry1AcMod effectively countered resistance to native Bt toxins Cry1Ab and ...

  10. Using plant nutrient landscapes to assess Anthropocene effects on insect herbivores.

    Science.gov (United States)

    Lenhart, Paul A

    2017-10-01

    Global climate change will dramatically affect insect herbivores through changes in plant quality. Linking how multiple climate factors affect plant macronutrient content may be the most accurate way to understand the response of insect herbivores. Studies should embrace the complexity of interacting climate factors in natural systems and characterize shifts in multidimensional plant nutrient landscapes. This nutrient landscape simplifies interpretation of climate effects, although selection of appropriate currencies, scale, and interactions with allelochemicals present challenges. By assessing climate change through the filter of nutrient landscapes we could gain an understanding of how complex interacting climate change drivers affect the 'buffet' available to different insect herbivores. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Pyrrolizidine alkaloid variation in Jacobaea hybrids: influence on resistance against generalist and specialist insect herbivores

    OpenAIRE

    Cheng, Dandan

    2012-01-01

    Plants produce a vast array of secondary metabolites (SMs). Some hypotheses were put forward to explain the diversity of structurally related SMs within the framework of plant defense against herbivores:1) SMs could be Selectively Neutral; 2) SM diversity is a result of the “Arms Race” between plants and the herbivores; 3) Plants benefit from the SM diversity because of the Synergistic Effects among the SMs; 4) The SM diversity may be a response to the Selection from Multiple Herbivores. In t...

  12. Why can't young fish eat plants? Neither digestive enzymes nor gut development preclude herbivory in the young of a stomachless marine herbivorous fish.

    Science.gov (United States)

    Day, Ryan D; German, Donovan P; Tibbetts, Ian R

    2011-01-01

    Most young fishes lack the ability to function as herbivores, which has been attributed to two aspects of the digestive system: elevated nitrogen demand and a critical gut capacity. We compared the digestive morphology and biochemistry of two size classes of the marine herbivore Hyporhamphus regularis ardelio, pre-ontogenetic trophic shift (pre-OTS, 100mm), to determine what limits the onset of herbivory and how their digestive processes fit with current models of digestion. Two gut-somatic indices comparing gut length to body length (relative gut length) and body mass (Zihler's Index) demonstrated a significant decrease (RGL 0.59→0.49, Penzyme activity between the two classes, with juveniles showing similar levels of carbohydrase and lipase and less protease compared with adults, indicating that juveniles did not preferentially target nitrogen and were as capable of digesting an herbivorous diet. These findings suggest that herbivory in this fish is not limited by the function of the post-oesophageal digestive tract, but rather the ability of the pharyngeal mill to mechanically process plants. Our findings offer partial support for the current model of stomachless digestion, indicating that further refinement may be necessary. Copyright © 2010 Elsevier Inc. All rights reserved.

  13. Habitat Heterogeneity Variably Influences Habitat Selection by Wild Herbivores in a Semi-Arid Tropical Savanna Ecosystem.

    Directory of Open Access Journals (Sweden)

    Victor K Muposhi

    Full Text Available An understanding of the habitat selection patterns by wild herbivores is critical for adaptive management, particularly towards ecosystem management and wildlife conservation in semi arid savanna ecosystems. We tested the following predictions: (i surface water availability, habitat quality and human presence have a strong influence on the spatial distribution of wild herbivores in the dry season, (ii habitat suitability for large herbivores would be higher compared to medium-sized herbivores in the dry season, and (iii spatial extent of suitable habitats for wild herbivores will be different between years, i.e., 2006 and 2010, in Matetsi Safari Area, Zimbabwe. MaxEnt modeling was done to determine the habitat suitability of large herbivores and medium-sized herbivores. MaxEnt modeling of habitat suitability for large herbivores using the environmental variables was successful for the selected species in 2006 and 2010, except for elephant (Loxodonta africana for the year 2010. Overall, large herbivores probability of occurrence was mostly influenced by distance from rivers. Distance from roads influenced much of the variability in the probability of occurrence of medium-sized herbivores. The overall predicted area for large and medium-sized herbivores was not different. Large herbivores may not necessarily utilize larger habitat patches over medium-sized herbivores due to the habitat homogenizing effect of water provisioning. Effect of surface water availability, proximity to riverine ecosystems and roads on habitat suitability of large and medium-sized herbivores in the dry season was highly variable thus could change from one year to another. We recommend adaptive management initiatives aimed at ensuring dynamic water supply in protected areas through temporal closure and or opening of water points to promote heterogeneity of wildlife habitats.

  14. Varying Herbivore Population Structure Correlates with Lack of Local Adaptation in a Geographic Variable Plant-Herbivore Interaction

    Science.gov (United States)

    Cogni, Rodrigo; Trigo, José R.; Futuyma, Douglas J.

    2011-01-01

    Local adaptation of parasites to their hosts due to coevolution is a central prediction of many theories in evolutionary biology. However, empirical studies looking for parasite local adaptation show great variation in outcomes, and the reasons for such variation are largely unknown. In a previous study, we showed adaptive differentiation in the arctiid moth Utetheisa ornatrix to its host plant, the pyrrolizidine alkaloid-bearing legume Crotalaria pallida, at the continental scale, but found no differentiation at the regional scale. In the present study, we sampled the same sites to investigate factors that may contribute to the lack of differentiation at the regional scale. We performed field observations that show that specialist and non-specialist polyphagous herbivore incidence varies among populations at both scales. With a series of common-garden experiments we show that some plant traits that may affect herbivory (pyrrolizidine alkaloids and extrafloral nectaries) vary at the regional scale, while other traits (trichomes and nitrogen content) just vary at the continental scale. These results, combined with our previous evidence for plant population differentiation based on larval performance on fresh fruits, suggest that U. ornatrix is subjected to divergent selection even at the regional scale. Finally, with a microsatellite study we investigated population structure of U. ornatrix. We found that population structure is not stable over time: we found population differentiation at the regional scale in the first year of sampling, but not in the second year. Unstable population structure of the herbivore is the most likely cause of the lack of regional adaptation. PMID:22220208

  15. 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.)

  16. Surface chemistry of photoluminescent F8BT conjugated polymer nanoparticles determines protein corona formation and internalization by phagocytic cells.

    Science.gov (United States)

    Ahmad Khanbeigi, Raha; Abelha, Thais Fedatto; Woods, Arcadia; Rastoin, Olivia; Harvey, Richard D; Jones, Marie-Christine; Forbes, Ben; Green, Mark A; Collins, Helen; Dailey, Lea Ann

    2015-03-09

    Conjugated polymer nanoparticles are being developed for a variety of diagnostic and theranostic applications. The conjugated polymer, F8BT, a polyfluorene derivative, was used as a model system to examine the biological behavior of conjugated polymer nanoparticle formulations stabilized with ionic (sodium dodecyl sulfate; F8BT-SDS; ∼207 nm; -31 mV) and nonionic (pegylated 12-hydroxystearate; F8BT-PEG; ∼175 nm; -5 mV) surfactants, and compared with polystyrene nanoparticles of a similar size (PS200; ∼217 nm; -40 mV). F8BT nanoparticles were as hydrophobic as PS200 (hydrophobic interaction chromatography index value: 0.96) and showed evidence of protein corona formation after incubation with serum-containing medium; however, unlike polystyrene, F8BT nanoparticles did not enrich specific proteins onto the nanoparticle surface. J774A.1 macrophage cells internalized approximately ∼20% and ∼60% of the F8BT-SDS and PS200 delivered dose (calculated by the ISDD model) in serum-supplemented and serum-free conditions, respectively, while cell association of F8BT-PEG was minimal (polymer nanoparticle surfactant stabilizer used determine particle internalization and biocompatibility profile.

  17. 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

  18. 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.

  19. 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.

  20. Neural coding merges sex and habitat chemosensory signals in an insect herbivore.

    Science.gov (United States)

    Trona, Federica; Anfora, Gianfranco; Balkenius, Anna; Bengtsson, Marie; Tasin, Marco; Knight, Alan; Janz, Niklas; Witzgall, Peter; Ignell, Rickard

    2013-06-07

    Understanding the processing of odour mixtures is a focus in olfaction research. Through a neuroethological approach, we demonstrate that different odour types, sex and habitat cues are coded together in an insect herbivore. Stronger flight attraction of codling moth males, Cydia pomonella, to blends of female sex pheromone and plant odour, compared with single compounds, was corroborated by functional imaging of the olfactory centres in the insect brain, the antennal lobes (ALs). The macroglomerular complex (MGC) in the AL, which is dedicated to pheromone perception, showed an enhanced response to blends of pheromone and plant signals, whereas the response in glomeruli surrounding the MGC was suppressed. Intracellular recordings from AL projection neurons that transmit odour information to higher brain centres, confirmed this synergistic interaction in the MGC. These findings underscore that, in nature, sex pheromone and plant odours are perceived as an ensemble. That mating and habitat cues are coded as blends in the MGC of the AL highlights the dual role of plant signals in habitat selection and in premating sexual communication. It suggests that the MGC is a common target for sexual and natural selection in moths, facilitating ecological speciation.

  1. 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.

  2. Responses by earthworms to reduced tillage in herbicide tolerant maize and Bt maize cropping systems

    DEFF Research Database (Denmark)

    Krogh, P. H.; Griffiths, B.; Demsar, D.

    2007-01-01

    -toxin producing transgenic maize line MON810 was studied for 1 year. At a Danish study site, Foulum (Jutland), one year of Bt corn was followed by 2 years of herbicide tolerant corn. At the French study site the most prominent effects observed were due to the tillage method where RT significantly reduced...... studies of Bt corn and a glufosinate ammonium tolerant corn and included a reduced tillage treatment (RT) and a conventional tillage treatment (CT) as examples of a likely concomitant change in the agricultural practise. At a French study site at Varois, (Bourgogne), a field grown with the Bt...

  3. Subtle interplay of competition and facilitation among small herbivores in coastal grasslands

    NARCIS (Netherlands)

    Stahl, J.; Van Der Graaf, A. J.; Drent, R. H.; Bakker, J. P.; Costa, Daniel

    2006-01-01

    1. Overlap in habitat use between herbivores can result in facilitative interactions, through enhancement of forage quality, as well as competitive interactions. The latter result from either interference or indirectly from resource depletion. 2. We investigated competitive and facilitative

  4. Dynamics of a plant-herbivore-predator system with plant-toxicity

    Science.gov (United States)

    Feng, Zhilan; Qiu, Zhipeng; Liu, Rongsong; DeAngelis, Donald L.

    2011-01-01

    A system of ordinary differential equations is considered that models the interactions of two plant species populations, an herbivore population, and a predator population. We use a toxin-determined functional response to describe the interactions between plant species and herbivores and use a Holling Type II functional response to model the interactions between herbivores and predators. In order to study how the predators impact the succession of vegetation, we derive invasion conditions under which a plant species can invade into an environment in which another plant species is co-existing with a herbivore population with or without a predator population. These conditions provide threshold quantities for several parameters that may play a key role in the dynamics of the system. Numerical simulations are conducted to reinforce the analytical results. This model can be applied to a boreal ecosystem trophic chain to examine the possible cascading effects of predator-control actions when plant species differ in their levels of toxic defense.

  5. Seasonal grazing and food preference of herbivores in a Posidonia oceanica meadow

    Directory of Open Access Journals (Sweden)

    Andrea Peirano

    2001-12-01

    Full Text Available Seasonal grazing of the fish Sarpa salpa (L., the urchin Paracentrotus lividus Lamarck and the isopods Idotea spp. was compared with the C/N ratio of adult and intermediate leaves and epiphytes of Posidonia oceanica (L. Delile, collected at three different depths. Despite seasonal differences in grazing, herbivores showed preferences throughout the year for adult leaves with more epiphyte and higher N contents. The maximum grazing on adult and intermediate leaves was observed in September and in June for fish and in March for urchins, whereas it was irregular for isopods. Grazing by the three herbivores was not related to their preference for leaves or epiphytes, notwithstanding the seasonal differences in their C and N contents. We concluded that herbivores show no preference for food type throughout the year and that seasonal consumption of P. oceanica is related mainly to herbivore behaviour.

  6. The bulldozer herbivore: how animals benefit from elephant modifying an African savanna

    NARCIS (Netherlands)

    Kohi, E.

    2013-01-01

    Herbivore-vegetation interactions are important structuring forces in savanna that modify the availability and quality of forage resources. Elephant for example, are known for their ability to change the vegetation structure through toppling trees, uprooting, snapping, debarking and breaking

  7. 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.

  8. Potential Use of Native and Naturalized Insect Herbivores and Fungal Pathogens of Aquatic and Wetland Plants

    National Research Council Canada - National Science Library

    Freedman, Jan E; Grodowitz, Michael J; Swindle, Robin; Nachtrieb, Julie G

    2007-01-01

    ...) scientists to identify naturalized and/or native herbivores of aquatic plants in an effort to develop alternative management strategies through an understanding of the agents' biology and ecology...

  9. Many roads to resistance: how invertebrates adapt to Bt toxins.

    Science.gov (United States)

    Griffitts, Joel S; Aroian, Raffi V

    2005-06-01

    The Cry family of Bacillus thuringiensis insecticidal and nematicidal proteins constitutes a valuable source of environmentally benign compounds for the control of insect pests and disease agents. An understanding of Cry toxin resistance at a molecular level will be critical to the long-term utility of this technology; it may also shed light on basic mechanisms used by other bacterial toxins that target specific organisms or cell types. Selection and cross-resistance studies have confirmed that genetic adaptation can elicit varying patterns of Cry toxin resistance, which has been associated with deficient protoxin activation by host proteases, and defective Cry toxin-binding cell surface molecules, such as cadherins, aminopeptidases and glycolipids. Recent work also suggests Cry toxin resistance may be induced in invertebrates as an active immune response. The use of model invertebrates, such as Caenorhabditis elegans and Drosophila melanogaster, as well as advances in insect genomics, are likely to accelerate efforts to clone Cry toxin resistance genes and come to a detailed and broad understanding of Cry toxin resistance.

  10. No effect of Bt Cry1Ie toxin on bacterial diversity in the midgut of the Chinese honey bees, Apis cerana cerana (Hymenoptera, Apidae).

    Science.gov (United States)

    Jia, Hui-Ru; Dai, Ping-Li; Geng, Li-Li; Jack, Cameron J; Li, Yun-He; Wu, Yan-Yan; Diao, Qing-Yun; Ellis, James D

    2017-01-31

    Cry1Ie protein derived from Bacillus thuringiensis (Bt) has been proposed as a promising candidate for the development of a new Bt-maize variety to control maize pests in China. We studied the response of the midgut bacterial community of Apis cerana cerana to Cry1Ie toxin under laboratory conditions. Newly emerged bees were fed one of the following treatments for 15 and 30 days: three concentrations of Cry1Ie toxin (20 ng/mL, 200 ng/mL, and 20 μg/mL) in sugar syrup, pure sugar syrup as a negative control and 48 ng/mL imidacloprid as a positive control. The relative abundance of 16S rRNA genes was measured by Quantitative Polymerase Chain Reaction and no apparent differences were found among treatments for any of these counts at any time point. Furthermore, the midgut bacterial structure and compositions were determined using high-throughput sequencing targeting the V3-V4 regions of the 16S rDNA. All core honey bee intestinal bacterial genera such as Lactobacillus, Bifidobacterium, Snodgrassella, and Gilliamella were detected, and no significant changes were found in the species diversity and richness for any bacterial taxa among treatments at different time points. These results suggest that Cry1Ie toxin may not affect gut bacterial communities of Chinese honey bees.

  11. SISTEM E-LEARNING DALAM PEMBELAJARAN iBT TOEFL (INTERNET BASE TEST OF ENGLISH AS A FOREIGN LANGUAGE MENGGUNAKAN MEDIA VOIP (VOICE OVER INTERNET PROTOCOL

    Directory of Open Access Journals (Sweden)

    Muchammad Husni

    2011-11-01

    Full Text Available Dengan semakin berkembangnya komunikasi internasional saat ini, seseorang dituntut untuk memiliki kemampuan berkomunikasi dalam bahasa global, diantaranya adalah bahasa Inggris. Salah satu alat untuk mengukur kemampuan berbahasa Inggris adalah dengan menggunakan TOEFL (Test of English as a Foreign Languge. iBT TOEFL ( Internet Base Test TOEFL mengukur kemampuan pembelajar untuk memahami, menggunakan dan mengerti bahasa Inggris ditingkat Universitas, disamping itu, test ini juga mengevaluasi seberapa baik pembelajar menggabungkan keterampilan mendengarkan/menyimak (listening, berbicara (speaking, membaca (reading, dan menulis (writing dalam bahasa Inggris. Penelitian ini akan mengembangkan Sistem E-learning untuk pembelajaran (Pelatihan dan Tes TOEFL menggunakan jaringan intranet yang dapat digunakan untuk mengukur kemampuan TOEFL pembelajar dengan memberikan hasil keluaran berupa kelemahan seseorang dalam menjawab soal-soal tes. iBT TOEFL terdiri atas 4 (empat bagian tes yaitu Listening, Writting, Reading dan Speaking. Sistem E-learning ini akan disertai dengan soal-soal latihan yang disesuaikan dengan kelemahan kemampuan TOEFL dari pembelajar/pengguna. Dengan demikian diharapkan Sistem E-learning ini dapat membantu pembelajar untuk meningkatkan kemampuan TOEFL sehingga target nilai TOEFL yang diinginkan dapat tercapai. Dalam sistem E-learning ini juga disediakan jalur komunikasi suara antara pembelajar/pengguna dengan penilai (assessor yang dikembangkan dengan teknologi VoIP untuk membantu pengguna dalam melatih teknik berbicara (speaking dalam bahasa Inggris.

  12. Tree diversity promotes generalist herbivore community patterns in a young subtropical forest experiment.

    Science.gov (United States)

    Zhang, Jiayong; Bruelheide, Helge; Chen, Xufei; Eichenberg, David; Kröber, Wenzel; Xu, Xuwen; Xu, Liting; Schuldt, Andreas

    2017-02-01

    Stand diversification is considered a promising management approach to increasing the multifunctionality and ecological stability of forests. However, how tree diversity affects higher trophic levels and their role in regulating forest functioning is not well explored particularly for (sub)tropical regions. We analyzed the effects of tree species richness, community composition, and functional diversity on the abundance, species richness, and beta diversity of important functional groups of herbivores and predators in a large-scale forest biodiversity experiment in south-east China. Tree species richness promoted the abundance, but not the species richness, of the dominant, generalist herbivores (especially, adult leaf chewers), probably through diet mixing effects. In contrast, tree richness did not affect the abundance of more specialized herbivores (larval leaf chewers, sap suckers) or predators (web and hunting spiders), and only increased the species richness of larval chewers. Leaf chemical diversity was unrelated to the arthropod data, and leaf morphological diversity only positively affected oligophagous herbivore and hunting spider abundance. However, richness and abundance of all arthropods showed relationships with community-weighted leaf trait means (CWM). The effects of trait diversity and CWMs probably reflect specific nutritional or habitat requirements. This is supported by the strong effects of tree species composition and CWMs on herbivore and spider beta diversity. Although specialized herbivores are generally assumed to determine herbivore effects in species-rich forests, our study suggests that generalist herbivores can be crucial for trophic interactions. Our results indicate that promoting pest control through stand diversification might require a stronger focus on identifying the best-performing tree species mixtures.

  13. 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.

  14. 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.

  15. Ecological consequences of plant hybridization in willows: inheritance patterns of secondary compounds and herbivore foraging behaviour

    Energy Technology Data Exchange (ETDEWEB)

    Hallgren, P. [Swedish Univ. of Agricultural Sciences, Umeaa (Sweden). Dept. of Animal Ecology

    2002-07-01

    Segregation of genetic variation into species is traditionally viewed as the principal unit of evolution while intraspecific hybridization was regarded as a mistake in nature. Nevertheless, intraspecific hybridization is common between many plant species and recent studies have suggested that hybridization may be beneficial to individuals. hybridization is also of interest as it influence species that are interacting with the hybridising species, for example herbivores that need to decide whether or not to forage on hybrids between host plants and non-host plants. To understand how herbivores are influenced by hybridization, and how herb ivory influences hybrid plants, I have studied the inheritance of plant resistance characters, foraging preference and performance of herbivores (leaf beetles and voles) and the degree of herbivore damage on pure and hybrid willows. The studied willow species, Salix caprea, S. repens and S. aurita differ in secondary metabolite composition. The results show that both studied groups of secondary metabolites, phenolic glucosides and condensed tannins, are additively inherited in hybrids between S. repens and S. caprea, while condensed tannins axe equal in S. caprea, S. aurita and hybrids between the two parental species. There is no common response of the studied herbivore community. Instead, it seems that specialist herbivores either discriminate against hybrids and non-host parental species or do not separate between hybrids and host parental species. In contrast, generalists usually show either intermediate preference for hybrids, or do not discriminate between hybrids and parental species. One generalist species shows a preference that indicates a breakdown in resistance. When adding together the effects of all herbivores, it appears that herbivores inflict more damage to hybrids than parental species.

  16. Induction of Systemic Resistance against Insect Herbivores in Plants by Beneficial Soil Microbes

    OpenAIRE

    Md. Harun-Or Rashid; Chung, Young R.

    2017-01-01

    Soil microorganisms with growth-promoting activities in plants, including rhizobacteria and rhizofungi, can improve plant health in a variety of different ways. These beneficial microbes may confer broad-spectrum resistance to insect herbivores. Here, we provide evidence that beneficial microbes modulate plant defenses against insect herbivores. Beneficial soil microorganisms can regulate hormone signaling including the jasmonic acid, ethylene and salicylic acid pathways, thereby leading to g...

  17. 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

  18. Modeling the Connections of Dynamic Sensor Fields Based on BT-Graph

    Directory of Open Access Journals (Sweden)

    Tuyen Phong Truong

    2016-03-01

    Full Text Available In this article, we propose a new approach to model and optimize the dynamic sensor field for both internal network connections and LEO satellite connection based on BT Graph. Due to the shift of LEO satellite’s orbit at each revolution, a dynamic sensor field (DSF, which is able to redetermine its gateways, is suitable to improve successful data communications. It is convenient to present a DSF as a BT-Graph that aims to utilize optimization algorithms. Parallel search algorithms are also deployed for more efficient execution time when DSFs consist of a significant large number of nodes. The simulation experiments are performed on an abstract forest fire surveillance network to validate our proposed approach.

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

    Science.gov (United States)

    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-text comments about the summaries. The nurses found the majority of the summaries to be understandable, accurate, and helpful (pgenerated summaries. In conclusion, natural language NICU shift summaries can be automatically generated from an electronic patient record, but our proof-of-concept software needs considerable additional development work before it can be deployed. PMID:21724739

  20. [Clinical experience with transurethral resection of bladder tumor (TUR-Bt) guided by photodynamic diagnosis (PDD)].

    Science.gov (United States)

    Inoue, Keiji; Kuno, Takahira; Fukuhara, Hideo; Hamaguchi, Takuya; Fukata, Satoshi; Karashima, Takashi; Kamada, Masayuki; Shuin, Taro; Sakakura, Naoki; Kasahara, Kotaro; Watanabe, Hironobu; Kozai, Tetsuo; Yasuda, Masaharu; Kataoka, Shinichi; Tanimura, Masanobu; Atsushi, Kurabayashi; Furihata, Mutsuo

    2009-11-01

    To report our clinical experience regarding transurethral resection of bladder tumor (TUR-Bt) guided by photodynamic diagnosis (PDD) with intravesical instillations of 5-aminolevulinic acid (ALA) and to assess the usefulness of the therapeutic method. TUR-Bt guided by PDD was performed in 57 patients of which 47 were men and 10 women with a median age of 74.3 years (range 45-90), 36 were primary cases and 21 were recurrent cases with non-muscle invasive bladder cancer. Two to two and half hours prior to endoscopy 1.5 g ALA dissolved in 50 ml of 8.4% sodium hydrogen carbonate (NaHCO3) solution was instilled intravesically. For fluorescence excitation a blue light source (D-LIGHT System, Karl Storz Endoscopy Japan K.K.) was used. The tumorous lesions under white light guidance and the lesion with fluorescent excitation under blue (fluorescence) light guidance were taken by cold cup as a biopsy and also resected sequentially. To evaluate the accuracy of PDD, the levels in images of the ALA-induced fluorescence were compared with the pathological results. To evaluate the availability of TUR-Bt guided by PDD, survival Analysis regarding vesical recurrence was retrospectively examined compared to the cases underwent conventional TUR-Bt under white light guidance. Moreover, in these cases, multivariate analysis using Cox proportional-hazards model was performed to detect the clinico-pathological factor independently contribute to improving prognosis. (Results) In the 301 specimens obtained from 57 patients, the sensitivity and specificity of PDD were 92.5% and 60.1%, whereas the sensitivity and specificity of conventional endoscopic examination under white light guidance were 81.6% and 79.5%, respectively. Median follow-up period was 19.1 (range 8.6-49.9) months in 57 patients underwent TUR-Bt guided by PDD. Eight of 57 patients recurred and recurrence-free survival rate was 88.2 +/- 0.1% (at 12 months) and 76.2 +/- 0.1% (24-48 months). Median follow-up period was 49.9 (5