Gene flow in the European corn borer Ostrinia nubilalis: implications for the sustainability of transgenic insecticidal maize

Strategies proposed for delaying resistance to Bacillus thuringiensis toxin s expressed by transgenic maize require intense gene flow between individua ls that grew on transgenic and on normal (referred to as refuges) plants. T o investigate gene flow in the European corn borer, Ostrinia nubilalis (Hub ner), the genetic variability at 29 sampled sites from France was studied b y comparing allozyme frequencies at six polymorphic loci. Almost no deviati ons from Hardy-Weinberg expectations occurred, and a high stability of alle lic distribution was found among samples collected in the same site over tw o or three different generations, indicating a high stability of the geneti c structure over time. The overall genetic differentiation was low at the r egion and whole country level, suggesting a high and homogeneous gene flow. These results are discussed in relation to the sustainability of transgeni c insecticidal maize.