Insecticide Confrontation in Dengue Vector: Enzymatic Characterization of Tolerance Level in the Mysore Field Populations of Aedes aegypti

Abstract

The susceptibility status of an insect population to any insecticide depends on several factors such includes genetic constitution, ecology of breeding place, previous history of insecticide application if any in that area and the cross resistance spectra. In view of the frequent outbreaks of dengue in different parts of the country and Karnataka state, in particular Mysore and surrounding districts, it is felt essential to generate a base line data on the susceptibility of vectors of local importance and their genetic differentiation through biochemical markers. Resistance to insecticides developed by Aedes aegypti was biochemically detected among its population collected from five different urban areas of Mysore city and from four rural locations of Mysore, Mandya and Hassan districts. Insect larvae exposed to different concentrations of insecticide - Deltamethrin for 24 hr. Insecticide resistance/tolerance level in terms of LC 50 and LC 90 for the insecticide was high in rural population than urban. Correspondingly, the reason for the resistance was detected through qualitative and quantitative analysis of three biochemical marker enzymes viz., A-Esterase, B-Esterase, Dehydrogenase (G6PD), and Phosphtases (Acid, Alkaline). The allelic frequency of Esterases and Phosphatases was more in rural over urban populations and the same was implied in quantitative estimation also. Wherein the allelic frequency of both the Phosphatases remains same in all the populations but the enzyme concentration was elevated in rural over the urban populations. The inspection of the present study reveals that, the Mysore populations of Ae. aegypti shows much variation for which their ecology was responsible.