CYTOCHROME-P-450 FIELD INSECTICIDE TOLERANCE AND DEVELOPMENT OF LABORATORY RESISTANCE IN GRAPE VINE POPULATIONS OF DROSOPHILA-MELANOGASTER (DIPTERA, DROSOPHILIDAE)

Studies were conducted between 1993 and 1996 using 3 natural grape vin e populations. 1 susceptible laboratory strain, and I resistant select ed strain of Drosophila melanogaster L. Pn vitro monooxygenase activit y (ethoxycoumarine-O-deethylation) (ECOD) was recorded from microsomal fractious of all strains. Results varied over a 6-fold range between susceptible laboratory Canton and resistant selected RDDT strains and over a 2-fold range between the Canton strain and natural populations of flies, Few significant variations of ECOD activities were detected among the natural populations despite many insecticide treatments, but activities were significantly correlated with toxicological tolerance to 5 of the 15 insecticides (deltamethrin. fipronil, chlorpyriphos et hyl, DDT, and diazinon). Moreover, immunoblotting responses of microso mal protein encoded by Cyp6A2 showed that the levels of expression wer e quantitatively correlated with toxicological tolerance to almost the same group of insecticides (deltamethrin, fipronil, chlorpyriphos eth yl, DDT, fenvalerate, and fenthion). However, tile level of CYP6A2 exp ression in some natural strains (still weakly resistant) was almost co mparable with one of the resistant strains. In vivo monooxygenase acti vity recorded in individual abdomens of flies showed that frequency di stributions of ECOD activity in natural populations overlapped those o f the resistant and laboratory strains, which were much narrower. Subs tantial and fast frequency changes (of the narrowness) that obtained i n laboratory were related to either the time of rearing of 1 of the na tural populations or selecting this population with an insecticide tha t has a toxicology correlated with both of the monooxygenase signs mea sured. Perspectives on using the CYP6A2 expression and ECOD activity f ur detecting a resistance mechanism by cytochrome P450 in field popula tions are discussed.