Bt Cotton’s Cry1ac No Harm to Predatory Bugs

Non-target herbivores feeding on Bt cotton can bio-accumulate the Cry1Ac toxin from the transgenic plant and pass it on to natural predators. However, predatory species are not affected by the toxin, said researchers at the Universidade Federal Rural de Pernambuco, Brazil and the University of Georgia.

The researchers investigated the movement of Cry1Ac toxin from the transgenic cotton plant to predators using three prey species fed with Bt-cotton. All three prey species were able to pass the Cry1Ac toxin to their respective predators. The researchers reported that the amount of toxin measured in the predators ranged from 4 to 17% of the amount in the herbivorous prey in their study.

Analysis of the developmental time, survival, longevity, and fecundity of the predator Posidus maculiventris indicated that those exposed to the Bt toxin had similar life history characteristics to those not exposed to the toxin. The researchers also reported that retention of the ingested Bt-toxins in non-target predators is relatively short. They observed that the toxin is undetectable in P. maculiventris after 48 hrs when it was switched back to prey fed with non-Bt cotton.

For more information, the paper can be accessed by subscribers to Transgenic Research at http://www.springerlink.com/content/6720174352336p64/.