Investigation of physiological insecticide resistance developed by mosquitoes in Çukurova

ABSTRACT Since 1 957, a considerable amount of different groups of insecticides has been used in Turkey especially in Adana, for the control of agricultural pests and vectors of Public Health importance The susceptibility tests have been successfully applied for many years to determine the insecticide resistance raised in pest and vector insects including An. sacharovi, the most important human malaria vector in Turkey. As this method does not allow to obtain sufficient information about physiological resistance, an alternative method of enzyme tests based on biochemical and genetic evaluations has been developed. In this study both methods were used for comparison. First of all the susceptibility for insecticides were tested in adult females of An. sacharovi collected in various seasons from Tabaklar and Herekli villages where insecticides are used intensively for both agricultural and vector control purposes and from Menekşe village where insecticide applications are more limited. Samples taken from laboratory colonies representing the mosquitoes under non-insecticide pressure during gonoactive season were also tested to compare with the field material. By the susceptibility test using lethal doses of DDT 4%, Malathion 5%, Propoxur %1, Deltamethrin 0.025% and Permethrin 0.25% each sample was divided into resistant and susceptible groups. Secondly the changes in the activity levels of enzymes were studied in these groups. Three enzymes were tested; Acetylcholine Esterase (AChE) which is the target site in the organophosphate and carbamate insecticide resistance, Glutathione S-Transferase (GST) which has a significant role in detoxification of organochlorine and pyrethroide insecticides and non-specific General Esterase which has a role in detoxification of all insecticides. The discriminant analysis which was used to understand the fitness between the grouping by susceptibility tests and the enzyme activity levels in these groups showed considerably high fitness rates 76.6% for AChE, 74.1 for GST and 62.2% for General Esterase. XIThe activities of the three enzymes were found in higher levels in resistant groups than susceptibles and also higher levels in gonoactive period than in hibernation season. It was also found that AchE, GST and General Esterase enzyme activities were higher in the localities under intensive insecticide application than in the localities where insecticides are used in lesser quantities or none. Keyword : An. sacharovi, insecticides, Resistance enzymes, Susceptibility tests XII