Levels of total acetylcholinesterase in Drosophila melanogaster in relation to insecticide resistance

Titration of acetylcholinesterase active sites was used to estimate the level of acetylcholinesterase in 82 Drosophila melanogaster strains originating from several countries. The amount of enzyme varied by up to a factor of twofold and was directly correlated with insecticide resistance. This suggests that increased acetyleholinesterase production contributes to resistance. This mechanism adds to the qualitative modifications of aceLylcholinesterase, which render me enzyme less sensitive to inhibition by insecticides. As these qualitative modifications of the active site of the enzyme usually result in a decrease in the rate of neurotransmitter hydrolysis, they may affect the fitness of the flies. Overproduction of a modified acetylcholinesterase appears to be a potential modifier since it compensates for the decrease in neurotransmitter hydrolysis. (C) 2001 Academic Press.