Scientists at the Plant Sciences Group of Wageningen UR in collaboration with the University of North Carolina (USA) have studied Bt cotton durability against lepidopteran pests. Research published in the journal Evolutionary Ecology showed that durability of Bt cotton may be due to the female insects preference to lay eggs in plants other than Bt cotton.

Bt cotton which has been planted extensively in China, India and the U.S. for over 13 years have always been accompanied with planting of refuge plants. This strategy was adapted because it was generally believed that the resistance to insects was not durable and could only be made to last longer by planting both resistant and non-resistant plants together thus reducing the selection pressure. Maarten Jongsma, scientist at Plant Research International of the Plant Sciences Group, said that "results show that the chance of breaking the resistance may be much smaller than the chance of changing insect behavioral preferences." This is because female moths are genetically determined to lay their eggs through her own preference and behavior. Females that prefer other plants than Bt cotton have a selective advantage since their offsprings will develop and reproduce elsewhere in nature without harming the cotton. Thus, the change in insect pest behavior ensures the durability of the plant resistance.

For details, see the story at http://www.wur.nl/UK/newsagenda/news/mot020310.htm.