Organophosphate resistance in Culex pipiens from Cyprus

Populations of Culex pipiens were sampled from 8 locations in Cyprus between 1987 and 1993. All population samples generally revealed organophosphate resistance to malathion, temephos, chlorpyrifos, fenthion, dichlorvos, and pirimiphos methyl, in decreasing order of magnitude. Of 7 populations assessed with the carbamate propoxur, all proved to be resistant to different degrees. Of the 6 populations tested with permethrin, 2 were resistant to permethrin. Resistance was associated with the presence of 5 different overproduced esterases (esterases A1, A2, A5, B2, and B5) as well as an insensitive form of acetylcholinesterase. These results are discussed in relation to the ongoing mosquito abatement program in Cyprus and to similar programs in other parts of the world.