Biochemical and Molecular Analysis of Acetylcholine Esterase to Rule out Organophosphorus Detoxification Level in Field Populations of Culex Quiquefasciatus Say

Abstract

Background & Objectives: Acetylcholinesterase, responsible for neurotransmitter degradation at the cholinergic nerve synapse, is the target of both organophosphate and carbamate insecticides. The current study envisage to assess acetylcholine esterase levels and mutation in the acetylcholine esterase gene1 of Cx. quinquefasciatus of Kozhikode, Cochin, Malappuram, Thrissur, and Palakkad town areas of Kerala, India. Methods: The samples were collected from regularly insecticide spraying area and scarcely spraying area of the five locations in the year 2014, 15 and 16. The assays were done according to the protocol provided in techniques to detect insecticide resistance mechanism; Field and laboratory Manual. Site specific mutation in acetylcholine esterase gene 1 was identified by RFLP using Alu1 enzyme. Results: The % remaining activity in propoxur inhibited fraction in the regularly and scarcely insecticide treating field populations of Cx.quinquefasciatus were higher than 30% and lesser than 30% respectively. The value greater than 30% indicates the chance to develop resistance in field populations. The RFLP using Alu1 on the ace1 also showed the presence of heterozygous genotype in all the five field populations except in Ernakulam where the Cx.quinquefasciatus population possessed homozygous resistant genotype, which is an indication to the excessive and extensive usage of Temephos as a larvicide. Interpretation & Conclusion: The evidence of development of resistance to synthetic insecticides in mosquitoes observed in the present study points to the need of employing new or alternate insecticides which would be easily degradable and have less harmful effect on other organisms.