Insecticide Resistance in Mosquito Populations: Mechanisms and Management

Abstract

Mosquito-borne diseases such as malaria, dengue, chikungunya, Zika, yellow fever and Japanese encephalitis remain major public-health challenges. Insecticides are an important component of mosquito-vector control, particularly through indoor residual spraying, insecticide-treated nets, larviciding and adult mosquito control. However, repeated and intensive use of insecticides has contributed to the evolution and spread of insecticide resistance in several mosquito species. Insecticide resistance is an inherited reduction in susceptibility that allows mosquitoes to survive exposure to doses that would normally kill susceptible individuals. The major mechanisms include target-site resistance, metabolic resistance, reduced penetration through the cuticle, and behavioural resistance. Target-site resistance commonly involves mutations such as kdr mutations in the voltage-gated sodium-channel gene, while metabolic resistance is associated with enhanced activity of cytochrome P450 monooxygenases, esterases and glutathione S-transferases. Resistance can reduce the effectiveness of vector-control programmes and may contribute to persistent transmission of mosquito-borne diseases. The World Health Organization (WHO) recommends systematic surveillance, standardized susceptibility testing, identification of resistance mechanisms and evidencebased selection of vector-control interventions. Integrated vector management, insecticide rotation or mosaic approaches where appropriate, synergists such as piperonyl butoxide (PBO) for suitable applications, biological control, environmental management and development of new vector-control technologies are important components of resistance management. This article reviews the mechanisms, causes, consequences, monitoring approaches and management strategies for insecticide resistance in mosquito populations and emphasizes the need for integrated and locally adapted approaches