Abstract
The polymorphism of two esterase loci (Est-1 and Est-2) was analyzed in relation to the sensitivity to Dursban (chlorpyrifos) organophosphosphorous insecticide in 12 natural populations from southern France. No correlation was observed between Est-1 polymorphism and Dursban sensitivity, but the increase of the Est-2(0.64) allele in the populations less sensitive to Dursban was highly significant (r=-0.9850 for 6 df).