Insecticide resistance of Culex pipiens (Diptera: Culicidae) in Turkey

Abstract

Insecticides are the primary means of controlling mosquitoes in Turkey, especially Culex pipiens and Anopheles maculipennis complex species. To better understand how the resistance status affects the success of vector control programs, we investigated the level of resistance of strains collected from seven localities to 4 larvicides (temephos, fenthion, Bacillus thuringiensis israilensis (Bti), and Bacillus sphaericus (Bs)) and 4 adulticides (DDT, malathion, deltamethrin, and permethrin) that are registered (except DDT) and are used heavily in mosquito control programs in Turkey. High levels of resistance were found to temephos in the Birecik, Viransehir, Mersin, Ankara, and Antalya strains, and we found resistance to fenthion in the Birecik, Mersin, Cankiri, and Antalya strains. Resistance levels to other larvicides (Bti and Bs) and strains (to temephos and fenthion) were less than 10-fold. We determined low mortality rates with the diagnostic dosage of DDT in all strains. Birecik and Viransehir mortality rates were lower than 30%. The diagnostic dosage mortality rates of the other adulticides varied widely (65.8% malathion Antalya, and 97.5% malathion Birecik, and deltamethrin Hatay) but Ankara and Antalya strains appeared to be resistant to all adulticides tested. The other strains were placed in the surveillance category according to the WHO categorization. Diagnostic dosage experiment results revealed that DDT resistance exists in all populations, although this insecticide has not been used for 30 years in Turkey. Our results indicated that Bti and Bs are very effective control agents for larval control while permethrin and deltamethrin are effective for adult control.