Transgenic insect-resistant Bt cotton expressing Cry1Ac/1Ab does not harm the insect predator Geocoris pallidipennis.

The large-scale commercial cultivation of genetically modified (GM) cotton has brought significant economic and environmental benefits. However, GM crops must undergo strict environmental monitoring and long-term observation. An important natural enemy insect in cotton fields, Geocoris pallidipennis , can ingest the Bt protein expressed in GM cotton by feeding on herbivorous insects that feed on the cotton. However, the potential risk of GM cotton to G. pallidipennis is still unclear. We here evaluated the effects of Bt cotton expressing the Cry1Ac/1Ab protein on nymphs and adults G. pallidipennis. Cry1Ac protein was detected in the midgut of the cotton bollworm, Helicoverpa armigera, after it ingested Bt cotton, and in the midgut of G. pallidipennis nymphs and adults preying on Bt-fed H. armigera. However, the survival rate, growth, development, and fecundity of G. pallidipennis were not adversely affected. Furthermore, G. pallidipennis cadherins, and those genes related to detoxification, antioxidant activity, nutrient utilization, and immune function were not differentially expressed in response to Cry1Ac exposure. Finally, we showed that Cry1Ac could not bind to brush border membrane vesicles (BBMV) proteins in G. pallidipennis nymphs or adults. In summary, these results indicate that the potential negative effect of transgenic Cry1Ac/1Ab cotton on the insect redator G. pallidipennis is negligible. [Display omitted] • Cry1Ac toxin expressed by Bt cotton can be transmitted to the predator Geocoris pallidipennis. • Cry1Ac-expressing Bt cotton did not affect the survival, growth and reproductive ability of G. pallidipennis. • Cry1Ac-expressing Bt cotton did not affect the expression of genes related to the detoxification and immunity of G. pallidipennis. • No Cry1Ac binding protein was detected in the midgut of G. pallidipennis. [ABSTRACT FROM AUTHOR]