Biochemical characterization of Aedes aegypti (Linnaeus) (Diptera: Culicidae) resistance to deltamethrin, fipronil, and imidacloprid.

Aedes aegypti is an important vector of dengue fever, dengue hemorrhagic fever and yellow fever, chikungunya, and Zika virus. The objective was to evaluate the resistance of A. aegypti exposed to insecticides with different action modes (deltamethrin, imidacloprid, and fipronil) under intense selection pressure for 10 generations in laboratory. Bioassays were conducted according to World Health Organization. Biochemical assay performed after selection with deltamethrin (Delta-SEL), fipronil (Fipro-SEL), and imidacloprid (Imida-SEL) from G to G was used for the assessment of detoxification enzymes (esterase (EST), acetylcholinesterase (AChE), glutathione S-transferases (GST), and acid and alkaline phosphatases (ACP and ALP)). The Fipro-SEL (G) had high resistance (77-fold), whereas Delta-SEL and Imida-SEL populations presented very high resistance with 118 and 372-fold, respectively, in comparison with unselected (UNSEL). The levels of EST, AChE, GST, ACP, and ALP enzymes amplified on application from G to G. The enzymes contributing in resistance development of insecticides were as follows: GST (20.7 µmol/min/mg of protein) in Delta-SEL (G), while AChE 9.71 µmol/min/mg of protein in Imida-SEL (G) and the peak ACP and ALP enzyme activities 13.32 and 12.93 µmol/min/mg of protein, respectively, in Fipro-SEL (G). The results showed that detoxification enzymes trigger insecticide resistance in A. aegypti and their suppression may aid in the resistance breakage.