Effects of transgenic Bacillus thuringiensis corn-fed prey on mortality and development time of immature Chrysoperla carnea (Neuroptera: Chrysopidae)
Authors: Hilbeck, A., Baumgartner, M., Fried, P.M., Bigler, F.
Journal, Volume, Year: Environmental Entomology, volume 27(2):480-487, 1998
Laboratory feeding experiments were conducted to determine the effects of Bt-fed herbivores (Ostrinia nubilalis and Spodoptera littoralis) on the predator Chrysoperla carnea. Bt corn (HD-1) coding for CryIAb and an isogenic strain were grown in greenhouses and used when they reached 50-80 cm (5-8 leaf stage). Mortality of chrysopid larvae raised on Bt-fed prey was significantly higher (67%) compared to those raised on Bt-free prey (37%). No differences were observed between chrysopid larvae raised on Bt-fed O. nubilalis or S. littoralis. Chrysopid larvae developmental time was prolonged when raised on Bt-fed O. nubilalis but not Bt-fed S. littoralis.
The experimental design of this study did not allow for differentiation between direct effects due to the Bt toxin versus indirect effects of consuming sick or dying prey that had succumbed to the Bt toxin. The dead or dying prey may have had limited nutritional value. In addition, chrysopid larvae were not given a choice in diet, which the have in the field. The study also had high mortality in the controls (34%), no prey-consumption data and no control using the purified Bt endotoxin.