Crop Biotech Update

No Deleterious Effect of Maize Bt Protein on Non Target Arthropods

May 30, 2008

Transgenic Bt maize varieties derived from the events Bt176 and MON810 were found to have no deleterious effect on the beneficial insect predator (Stethorus punctillum). The study which investigated prey-mediated effects of two maize varieties expressing a truncated Cry1Ab protein was conducted by the group of Fernando Alvarez-Alfageme at the Centre of Biological Research in Spain. Spain is a major Bt maize growing country in Europe with more than 75,000 hectares in 2007. Bt maize was first commercially planted in the country in 1998.

The researchers studied the survival of the insect predator, their developmental time to adulthood, and fecundity when exposed to its prey, the red spider mite T. urticae, reared on Bt and non Bt maize leaves. Commercial Bt maize varieties Compa CB (Bt176) and DKC7565 (MON810) with corresponding non-transformed near isogenic varieties Brasco and Tietar were used in their experiments. The results from feeding
trials showed that neither Bt maize variety caused any negative effects on any of the parameters studied. The group reports that the predator midgut lacks specific receptors for the active Bt toxin to bind to.

The paper is available to journal subscribers at