ESTERASES A5-B5 IN ORGANOPHOSPHATE-RESISTANT CULEX-PIPIENS FROM ITALY

Culex pipiens mosquitoes from Lignano city, Udine province, northeast Italy, were found to carry over-produced non-specific esterases A1, A2 -B2 and A4-B4 or A5-B5, detected by starch gel electrophoresis, giving multiple resistance to organophosphorus insecticides. Tn order to dif ferentiate between A4-B4 and A5-B5 esterases, the latter known only fr om Cyprus whereas the former is widespread in Italy and elsewhere, res triction fragment length polymorphism (RFLP) analysis was performed at the esterase B locus. Both B4 and B5 haplotypes were found. This is t he first record of A5-B5 esterase-mediated resistance in continental E urope.