Effect of Bt cotton on important insect pests and their natural enemies

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dc.contributor.advisorAggarwal, Naveen
dc.contributor.authorJagdeep Kaur
dc.date.accessioned2018-05-27T06:17:03Z
dc.date.available2018-05-27T06:17:03Z
dc.date.issued2017
dc.description.abstractThe studies on the effect of Bt cotton on some important pests and their natural enemies were conducted at Punjab Agricultural University, Ludhiana during 2015 and 2016. The Cry toxin concentration estimation at the three trophic levels of Bt cotton plant, prey (Aphis gossypii Glover) and predators, Cheilomenes sexmaculatus (Fabricius) and Chrysoperla zastrowi sillemi (Esben-Petersen) revealed maximum Cry1Ac and Cry2Ab concentration in cotton leaves in the treatment of 60 days old Bt plants and minimum concentration in cotton leaves of 40 days old Bt plants. While, in similar experiment with Bt cotton leaves, prey (Bemisia tabaci Gennadius) and predators (C. sexmaculatus and C. z. sillemi), maximum Cry toxins concentration in Bt cotton leaves was observed at 70 days and minimum concentration in 110 days old Bt plants. In the tritrophic experiment of Bt cotton, aphid and C. sexmaculatus at second trophic level, we found mean values of 0.24, 0.41µg/g FW of Cry1Ac and Cry2Ab toxins respectively, in aphids reared on Bt cotton. Whereas, in Bt cotton, whitefly and C. sexmaculatus tritrophic experiment, 0.31, 0.52 µg/g FW of Cry1Ac and Cry2Ab toxins were detected in whiteflies. Further, the flow of these toxins in the predator, C. sexmaculatus adults has been recorded with the values of 0.04, 0.09 µg/g FW of Cry1Ac and 0.07, 0.19 µg/g FW of Cry2Ab toxins in case of aphid and whitefly feeding. In the tritrophic experiment of Bt cotton, aphid and C. z. sillemi at second trophic level, mean values of 0.20, 0.38 µg/g FW of Cry1Ac and Cry2Ab toxins respectively, were recorded in aphids reared on Bt cotton. Whereas, in Bt cotton, whitefly and C. z. sillemi tritrophic experiment, 0.24, 0.37 µg/g FW of Cry1Ac and Cry2Ab toxins were detected in whiteflies. At the third trophic level in predator, C. z. sillemi adults, 0.06, 0.07 µg/g FW of Cry1Ac and 0.08, 0.09 µg/g FW of Cry2Ab toxins were recorded in case of aphid and whitefly feeding.When the Bt toxin reared prey, A. gossypii and B. tabaci were used in the tritrophic feeding bioassay experiments with C. sexmaculatus and C. z. sillemi, no significant indirect effects of Cry toxins were observed on the various developmental and reproductive parameters of both the predators. Though, slightly lower larval survival, fecundity, adult emergence and longevity were recorded in predators fed with Bt reared prey. In the abundance and diversity studies in Bt and non-Bt cotton under field conditions, a total of 70 and 73 species of arthropods distributed over 12 orders belonging to 48 and 50 families were found to be associated with the cotton crop during 2015 and 2016, respectively. Among the different categories of the pests, four species of target insect pests, nine species of sucking insect pests, 25 species of natural enemies and 32 and 35 species of non-target insects were recorded from Bt and non-Bt cotton during two years. BG II cotton did not significantly affect the arthropod abundance, species richness and diversity indices of arthropods with some exceptions of target insect pests (bollworms) as their population was negligible in the Bt treatments. The abundance of sucking insect pests was significantly more in Bt cotton plots during the year 2015 in comparison to 2016. Moreover, arthropod abundance, species richness and diversity indices were more under unprotected conditions as compared to treated plots in Bt and non-Bt cotton. On the whole, cultivation of BG II cotton did not pose any adverse effect on biodiversity including natural enemies found in cotton ecosystem.en_US
dc.identifier.urihttp://krishikosh.egranth.ac.in/handle/1/5810047785
dc.keywordsArthropods, biodiversity, Bt cotton, Cry toxins, Cheilomenes sexmaculatus, Chrysoperla zastrowi sillemi, indirect effects, trophic levelen_US
dc.language.isoenen_US
dc.pages139en_US
dc.publisherPunjab Agricultural University, Ludhianaen_US
dc.research.problemEffect of Bt cotton on important insect pests and their natural enemiesen_US
dc.subEntomologyen_US
dc.subjectnullen_US
dc.themeEffect of Bt cotton on important insect pests and their natural enemiesen_US
dc.these.typePh.Den_US
dc.titleEffect of Bt cotton on important insect pests and their natural enemiesen_US
dc.typeThesisen_US
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