Insecticide resistance and malaria transmission: divergent effects on Anopheles vector competence

The global reduction of malaria burden through the use of insecticides in the form of insecticide-treated nets (ITNs) or indoor residual spraying has been challenged with insecticide resistance among species of Anopheles mosquitoes. The challenge is due to resistance mechanisms such as target site mutation, metabolic resistance, cuticular thickening, and behavioral resistance. Despite few studies reporting significant influence of insecticide exposure on vector competence-a mosquito's ability to infect, harbour, and transmit Plasmodium - the relationship between insecticide exposure in mosquitoes and vector competence remains poorly understood and underexplored. While some studies have reported on the impairment of parasite development in mosquitoes, some others concluded that vector competence in mosquitoes is enhanced by insecticide exposure. This review therefore reports on recent knowledge about the effects of insecticide resistance on vector competence for malaria transmission in Anopheles populations. We argue that the integration of omics-based approaches that embrace ecological reality is crucial for addressing current contradictions observed and accurately predicting epidemiological implications of insecticide resistance in malaria transmission.