Cry1F Maize Has No Adverse Effects on Cotesia marginiventris

Fall army worm is one of the major pests in maize especially in the United States and tropical areas in the western hemisphere. Bt maize expressing insecticidal Cry1F protein was planted in 2011 to combat fall army worm infestation. In 2006, a population of fall army worms in Puerto Rico was found to have evolved resistance to Cry1F maize in the field. Jun-Ce Tian from Cornell University and colleagues used the resistant population to evaluate the effects of Cry1F on Cotesia marginiventris, a wasp parasitoid of fall army worms. The researchers used resistant fall army worms to eliminate possible prey-mediated effects and avoid concerns about potential differences in laboratory- or field-derived Bt resistance.

Results showed that Cry1F maize had no effects on the development, parasitism, survivorship, sex ratio, longevity, and fecundity of C. marginiventris parasitizing fall army worms fed with Cry1F maize. The researchers also found out that the concentration of Cry1F in the leaves of maize was significantly decreased when fed by the fall army worms, and was undetectable in larvae, cocoons or adults of the wasp parasitoid. The results of this study disprove the earlier reports that Bt proteins harm C. marginiventris. The authors said that the results of those reports were caused by prey-mediated effects due to Bt-susceptible insect hosts.

Read the abstract of the study at http://link.springer.com/article/10.1007/s11248-013-9748-x.