Assessments of prey-mediated effects of Bt corn demonstrate no adverse effects of Cry1F on Coleomegilla maculata

The ladybird beetle, Coleomegilla maculata (DeGeer), is a common and abundant predator that suppresses pest populations in many cropping systems. Its larvae and adults are polyphagous, feeding on aphids, thrips, lepidopteran eggs and larvae as well as plant tissues. Thus, C. maculata may be exposed by several means to insecticidal proteins expressed in genetically engineered crops expressing insecticidal proteins from Bacillus thuringiensis (Bt). We evaluated the potential impact of Cry1F expressing corn (Mycogen 2A517) on several fitness parameters of C. maculata over two generations using Bt-resistant Spodoptera frugiperda (JE Smith) larvae as prey. Survival, duration of larval and pupal stages, adult weight and female fecundity of C. maculata were not different when they were fed resistant S. frugiperda larvae reared on either Bt or control corn leaves for both generations. ELISA and sensitive-insect bioassays showed C. maculata were exposed to bioactive Cry1F protein. However, the insecticidal protein had no effect on C. maculata larvae, although the larvae contained 20-30 ng Cry1F/g fresh weight. Our results demonstrate that Cry 1F expressing corn did not affect important fitness parameters of C. maculata and that Cry1F protein did not accumulate but decomposed when transferred during trophic interactions.