[Esterase patterns in Culex (C.) quinquefasciatus Say, 1823, and its relation to malathion organophosphate insecticide resistance].

This paper describes the esterase patterns found in a wild strain of Culex quinquefasciatus which was known to bear resistance genes and the existence of genetic polymorphism for such esterases is demonstrated. The most frequent polymorphisms found were Est-1, Est-2, and Est-3; Est-2 was possibly responsible for Culex quinquefasciatus resistance. The frequency of potentially resistant females was significantly higher as compared to males: in addition, the hypothesis was proposed that heterozygotie Est-3 is selected as a genotype which may contribute to resistance in neotropical areas.