Silent Threat: Insecticide Resistance and Escalating Dengue Cases in India

The increasing incidence of dengue in India coincides with growing insecticide resistance in Aedes mosquito populations, undermining the efficacy of conventional vector control strategies. The introduction of DDT in the 1940s revolutionized mosquito control, forming the backbone of the global malaria eradication efforts, but widespread resistance and environmental concerns led to its reduced use. Subsequent adoption of organophosphates and carbamates provided effective alternatives by inhibiting acetylcholinesterase, though resistance again emerged across vector populations. The development of pyrethroids in the 1980s enabled low-dose, cost-effective vector control interventions like insecticide-treated nets and indoor residual spraying, significantly reducing the burden of vector borne diseases. However, rapid expansion of resistance at global scale compromised their long-term effectiveness. In response to these limitations, WHO promoted integrated vector management and facilitated the deployment of newer classes of insecticides such as neonicotinoids, microbial larvicides, and insect growth regulators to combat resistance and ensure sustainable control. This review provides a comprehensive analysis of the evolution of insecticide resistance. Specifically, it elucidates the mode of action of major classes of insecticide, the resistance mechanisms, and context-dependent deployment strategies crucial for preserving the effectiveness of vector control interventions against dengue, malaria, Zika, and other vector-borne diseases.