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Crop Biotech Update

Seed Mixtures vs Structured Refuges for Bt Hybrids

May 7, 2010

Putting up a refuge to prolong the effectiveness of Bt hybrids against pests has been the recommended practice. However, growers are hoping that this regulation will change in time as more science is put into insect pest management and stewardship. Recently, a journal article published by Purdue University entomologists described some of the benefits as well as drawbacks associated with seed mixtures as a refuge for western corn rootworms.

The article in the Journal of Economic Entomology reported the results of field studies comparing seven treatments: block refuges of 10% and 20% strip, strip refuges of 10% and 20%, seed mixture refuges of 10% and 20% and a 100% refuge. The authors concluded that the use of seed mixtures is advantageous because of its convenience to growers and that "mixing the seed may facilitate random mating because of increased proximity of adult beetles in both space and time, theoretically enhancing resistance management." On the other hand, it can also be a disadvantage for potential larval movement between refuge and insect resistant crops "can reduce the number of susceptible beetles while increasing the number of potential heterozygotes and exposure of later-instar larvae to sublethal doses of Bt toxin."

More on this article can be read at  http://ipm.illinois.edu/bulletin/article.php?id=1290