Dhillon M K, Sharma H C
Division of Entomology, Indian Agricultural Research Institute (IARI), New Delhi-110 102, India.
J Environ Biol. 2013 Jan;34(1):67-73.
The effectiveness of commercial Bt-cotton in pest management, influence on arthropod diversity, natural enemies, and toxin flow in the insect fauna under field conditions were studied keeping in view the need to assess bioefficacy and biosafety of Bt-transgenic cotton. There were no significant differences in oviposition by Helicoverpa armigera on Bt-transgenic and non-transgenic cottons (9.2 versus 9.6 eggs plants(-100)), while the numbers of H. armigera larvae were significantly more on non-transgenic than on Bt-transgenic (10.4 versus 4.0 larvae plants(-100)) cotton. The Bt-cotton had significantly more number of mature opened bolls (9.6 versus 4.4 bolls plant(-1)), lower bollworm damage (12.8 versus 40.2% bolls damaged), and higher seedcotton yield (667.7 versus 231.7 kg ha 1). Population of cotton leafhopper, Amrasca biguttula biguttula was lower (582.2 versus 732.2 leafhoppers plants(-100)), while that of whitefly, Bemisia tabaci was higher on Bt-transgenic (65.2 versus 45.6 whiteflies plants(-100)) than on non-transgenic cotton. There was no significant influence of Bt-transgenic cotton on abundance of natural enemies of crop pests - chrysopids (9.6 versus 8.4 chrysopids plants(-100), ladybird beetles (16.0 versus 10.8 ladybirds plants(-100)), and spiders (128.4 versus 142.8 spiders plants(-100)). There were no significant differences in H. ormigera egg (19.8 versus 20.9%), larval (7.4 versus 9.6%), and larval-pupal (1.3 versus 2.9%) parasitism on Bt-transgenic and non-transgenic cottons in the farmer's fields. The parasitism in larvae of H. armigera was far lower than that of the eggs, which might be because of early mortality of H. armigera prior to parasitoid development in the host larvae. Although, Cry1Ac Bt toxin was detected in Cheilomenes sexmoculatus, chrysopids, A. bigutulla bigutulla, Thrips taboci, Myllocerus sp., Oxycarenus laetus, Dysdercus koenigii, spiders, bugs, and grasshoppers, no significant differences were observed in their abundance on Bt-transgenic and non-transgenic cottons, suggesting that there were no adverse effects of Bt-cotton on the arthropod diversity under field conditions.
考虑到评估转基因抗虫棉生物有效性和生物安全性的必要性，研究了商业化种植的转基因抗虫棉在田间条件下对害虫治理的有效性、对节肢动物多样性、天敌以及昆虫群落中毒素流动的影响。棉铃虫在转基因抗虫棉和非转基因棉上的产卵量没有显著差异（分别为每百株9.2枚卵和9.6枚卵），而棉铃虫幼虫数量在非转基因棉上显著多于转基因抗虫棉（分别为每百株10.4头幼虫和4.0头幼虫）。转基因抗虫棉成熟开放棉铃数量显著更多（分别为每株9.6个棉铃和4.4个棉铃），棉铃虫危害更低（棉铃受害率分别为12.8%和40.2%），籽棉产量更高（分别为每公顷667.7千克和231.7千克）。棉叶蝉，棉二点叶蝉的种群数量在转基因抗虫棉上更低（分别为每百株582.2头叶蝉和732.2头叶蝉），而烟粉虱，烟粉虱在转基因抗虫棉上的种群数量更高（分别为每百株65.2头粉虱和45.6头粉虱）。转基因抗虫棉对作物害虫天敌草蛉（分别为每百株9.6头草蛉和8.4头草蛉）、瓢虫（分别为每百株16.0只瓢虫和10.8只瓢虫）和蜘蛛（分别为每百株128.4只蜘蛛和142.8只蜘蛛）的丰富度没有显著影响。在农民田间，转基因抗虫棉和非转基因棉上棉铃虫卵（分别为19.8%和20.9%）、幼虫（分别为7.4%和9.6%）以及幼虫 - 蛹（分别为1.3%和2.9%）的寄生率没有显著差异。棉铃虫幼虫的寄生率远低于卵的寄生率，这可能是因为棉铃虫在寄生蜂在宿主体内发育之前就过早死亡。虽然在六斑月瓢虫、草蛉、棉二点叶蝉、西花蓟马、瘤背豆象、宽黾蝽、红蝽、蜘蛛、蝽象和蝗虫中检测到了Cry1Ac Bt毒素，但在转基因抗虫棉和非转基因棉上它们的丰富度没有显著差异，这表明在田间条件下转基因抗虫棉对节肢动物多样性没有不利影响。
