| Summary: | The control of insect vectors, such as mosquitoes relies majorly on the use of insecticides. Most studies on insecticidal efficacy on mosquitoes have placed emphasis exclusively on lethal dosages. Whereas, sublethal doses of insecticide can alter the mosquito biology, physiology, behaviour and demographic parameters. Continuous and indiscriminate use of insecticides have created resistance problem which has reduced the efficacy of some insecticides. The pyrethroids (Py) and organophosphates (OPs) are most widely used, OPs inactivate acetylcholinesterase by phosphorylating or carbamylating the active serine, it also increases protein turn over and glycolytic activity while pyrethroid acts as a sodium channel modulator. In this study, Culex quinquefasciatus (Say) were used to estimate the effect of sublethal dosages of cypermethrin insecticide on tissue protein and carbohydrate levels and; acetylcholinesterase (AChE) and glutathione S-transferase (GST) activation levels. Culex quinquefasciatus (Say) used were reared in the laboratory with sucrose solution (10%) supplied daily as food source of carbohydrate while blood meal was provided for the adult females from white albino rats with body hair shaved off. In all cases, sublethal cypermethrin concentrations effect significant changes in the levels of tissue biochemicals; with increase in sublethal concentrations of cypermethrin, the tissue carbohydrate levels decreased significantly (F = 30.559, df = 8, 48, Sig. = 0.000 (P < 0.05) and AChE activation levels increased significantly (F = 22.414, df = 8, 48, Sig. = 0.000 (P < 0.05). Hence, sub lethal effects of insecticides on insect population is invaluable in the understanding of resistance population and the need to manage it. This effort will help in the prioritization and determination of the effective dosage of insecticides in mosquito control. Keywords: Acetylcholinesterase, Gluthathione-S-transferases, Tissues, Protein, Carbohydrate, larva, Lethal concentration (LC), Culex quinquefasciatus
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