Bt-transgenic technology may be especially vulnerable because insects are treated with a high dose of toxin even when they are not causing economic damage. This produces a highly constant selection pressure. One of the strategies to delay resistance is using seed mixture strategy, toxin-free and toxin-containing plants within the same field. However, it is expected that insect dispersal may alter the effectiveness of this strategy. There is little information available on larval dispersal of lepidopterous pests in corn, one of the major transgenic crops. An aim of our experiments was to determine whether or not endotoxins of Bacillus thuringiensis expressed in sweet corn tissues would affect the fall armyworm (FAW) larval dispersion. Natural and artificial infestations of the FAW were studied on sweet corn fields. The plants included transgenic sweet corn plants originating from the BT 11 transformation event that expressed the Cry 1A(b) toxin from Bt (Attribute™), and untransformed, near isogenic conventional sweet corn plants (Prime Plus™). Results indicated that more than 50% of surviving FAW larvae dispersed among neighboring plants from the source of infestation within the same row. Movement to neighboring rows represents less than 20% of the total number of survivors. Overall, larvae dispersed similarly on transgenic and conventional plants. The failure of seed-mixture strategy is likely to occur under these conditions.
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA