Advertisement
Advertisement

More Related Content

Advertisement

More from ICRISAT(20)

Advertisement

Applied genomics @ ICRISAT

  1. Biosafety of Transgenic Crops to Natural Enemies of Cotton Bollworm/Legume Pod Borer, Helicoverpa armigera Nov 2009 To ensure sustainable deployment of transgenic insect-resistant plants, it is important that they are compatible with other control methods, including the natural enemies. Therefore, we studied the effects of transgenic cotton expressing Bacillus thuringiensis (Bt) toxin proteins on the parasitization of Helicoverpa armigera Bt toxin was detected in cocoons of the parasitoid. Reduction in cocoon formation was due to early mortality of H. armigera rather than the direct effects of Bt toxin on the parasitoid. Effect of Bt intoxicated H. armigera larvae on the predator, Cheilomenes sexmaculatus Plate 1. Ichneumonid, Campoletis chlorideae parasitizing Helicoverpa armigera larva (1a), cotton aphid, Aphis gossypii (1b), and the coccinellid, Cheilomenes sexmaculatus (1c). Materials and Methods H. armigera was monitored in Bt-transgenic and non-transgenic Bt C. chlorideae, the H. armigera larvae were reared on Bt-transgenic and non-transgenic cottons. H. armigera of Bt (0.05%) and untreated control diet were offered to the grubs of the coccinellid predator, C. sexmaculatus. Bt-transgenic cotton on the predatory coccinellid, larvae of C. sexmaculatus were reared on A. gossypii fed on Bt-transgenic and the non-transgenic cottons (Mech 12 and RCH 2). Fig. 1. Parasitization of Helicoverpa on transgenic and non-transgenic cottons in farmer’s fields (1a), and effect of Bt-transgenic cotton on cocoon formation of larval parasitoid, Campoletis chlorideae (1b). ++ Helicoverpa larvae fed on transgenic cottons before and after parasitization. -- Helicoverpa larvae fed on non-transgenic cottons. conditions, and the effects of Bt-transgenic cotton and Bt CRY toxin proteins on Campoletis chlorideae (Plate 1a), and the generalist predator, Cheilomemes sexmaculatus (Plate 1c) under laboratory conditions through intoxicated H. armigera larvae, and the cotton aphid, Aphis gossypii (Plate 1b). Results and Discussion Influence of Bt-transgenic cottons on parasitization of Helicoverpa armigera Trichogramma spp. was greater in Bt-transgenic than in non-transgenic cottons (Fig. 1a). parasitism by C. chlorideae and Eriborus spp., and no larval-pupal tachinid parasitoids were recorded in Bt cotton. C. chlorideae reared on H. armigera fed on Bt-transgenic cottons was (Fig. 1b). Conclusions However, Bt effects of Bt toxins on the natural enemies. Bt-transgenic crops on the natural enemies are far lower than those of the synthetic pesticides, which result in complete elimination of the natural enemies. Acknowledgments: C. sexmaculatus fed on H. armigera larvae reared on Bt intoxicated diet increased by 1.5 days (Fig. 2a, b). However, there was no effect on adult emergence (Fig. 2a). Bt protein were detected in C. sexmaculatus larvae when fed on H. armigera larvae raised on Bt intoxicated Fig. 2. Development period and adult emergence of Cheilomenes sexmaculatus fed on Helicoverpa armigera larvae reared on Bt intoxicated Effect of Bt-transgenic cotton reared Aphis gossypii on Cheilomenes sexmaculatus C. sexmaculatus reared on Bt-transgenic cotton fed A. gossypii increased by 1 to 1.5 days (Fig. 3a), and the adult emergence decreased by 13 to 40% (Fig. 3b). <0.5 ppb) of Bt protein in A. gossypii and C. sexmaculatus adults, and moderate levels (>2.5 ppb) in C. sexmaculatus larvae (Fig. 4). Fig. 4. Detection of Bt toxins in different stages of Cheilomenes sexmaculatus and Aphis gossypii. Fig. 3. Development period (3a) and adult emergence (3b) of Cheilomenes sexmaculatus reared on Bt-transgenic and non- transgenic cotton fed Aphis gossypii. a a b b c
Advertisement