RESISTANCE-ASSOCIATED POINT MUTATIONS IN INSECTICIDE-INSENSITIVE ACETYLCHOLINESTERASE

Extensive utilization of pesticides against insects provides us with a good model for studying the adaptation of a eukaryotic genome to a st rong selective pressure. One mechanism of resistance is the alteration of acetylcholinesterase (EC 3.1.1.7), the molecular target for organo phosphates and carbamates. Here, we report the sequence analysis of th e Ace gene in several resistant field strains of Drosophila melanogast er. This analysis resulted in the identification of five point mutatio ns associated with reduced sensitivities to insecticides. In some case s, several of these mutations were found to be combined in the same pr otein, leading to different resistance patterns. Our results suggest t hat recombination between resistant alleles preexisting in natural pop ulations is a mechanism by which insects rapidly adapt to new selectiv e pressures.