Laboratory and field evaluations demonstrate no acute survival or abundance deficits in insect predators fed transgenic Bacillus thuringiensis corn, suggesting safety for natural enemies.
Laboratory studies determined the effects of feeding corn, Zea mays L., pollen expressing a Cry1Ab protein derived from Bacillus thuringiensis (Berliner) subsp. kurstaki on 3 predatory species: Coleomegilla maculata DeGeer (Coleoptera: Coccinellidae), Orius insidiosus Say (Heteroptera: Anthocoridae), and Chrysoperla carnea Stephens (Neuroptera: Chrysopidae). No acute detrimental effects of the transgenic B. thuringiensis pollen (Cry1Ab protein) on preimaginal development and survival were observed among these predators. The following percentage survival values (±SE) were observed: C. maculata , 89 ± 2.2% ( B. thuringiensis corn pollen), 69 ± 5.9% (non- B. thuringiensis corn pollen); O. insidiosus , 63 ± 12% ( B. thuringiensis corn pollen), 44 ± 10.2% (non- B. thuringiensis corn pollen); and C. carnea , 49 ± 3.5% ( B. thuringiensis and non- B. thuringiensis corn pollen). No detrimental effects were observed in the abundance of Ostrinia nubilalis (Hübner) (Lepidoptera: Pyralidae) predators (coccinellids, anthocorids, chrysopids) in B. thuringiensis corn compared with non- B. thuringiensis corn during 2 yr of field evaluations. Predator numbers observed before, during, and after pollen shed suggest that B. thuringiensis corn pollen will not affect natural enemy movement in corn. Additional studies are needed to test for chronic and reproductive effects over several generations before concluding that transgenic B. thuringiensis corn pollen has no effect on insect predators.
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Pilcher et al. (1997) studied this question.