The Anopheles mosquitoes transmit malaria. What are the resistance mechanisms that evolved in these malaria vectors? How do these mechanisms help them avoid being killed by insecticides used in vector control?

Nadja Wipf studied insecticide resistance in Anopheles mosquitoes from Côte d’Ivoire. In this video, she leads you through the different mechanisms that help mosquitoes survive insecticides. These mechanisms include behavioural, cuticular, metabolic and target site resistance. Further challenges are cross-resistance and multiple resistance to insecticides.

Knowing the underlying resistance mechanism is essential for choosing the Insecticide Resistance Management strategy (IRM) that is tailored to control the local mosquito population. Cross-resistance, for instance, means that a mechanism responsible for resistance to one insecticide also allows mosquitoes to resist other insecticides with the same mode of action. Thus, you need to reflect carefully when switching from one insecticide to another.

Nadja explains cross-resistance between insecticides of the two classes pyrethroids and organochlorines. But cross-resistance also happens between other insecticide classes. Here is an additional example: Organophosphate and carbamate insecticides are both acetylcholinesterase inhibitors. ACE–1 mutation is a single point mutation that leads to an amino acid substitution. In malaria vectors, this reduces the binding of acetylcholinesterase inhibitors. It confers a cross-resistance between organophosphate and carbamate insecticides.

After you’ve watched the video, think about what the important questions are when encountering resistance in a field mosquito population and share them in the comment section.

References

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Carrasco, D, Lefevre, T, Moiroux, N, Pennetier, C, Chandre, F, Cohuet, A. Behavioural adaptations of mosquito vectors to insecticide control. 2019. Curr Opin Insect Sci, 34, 48-54.

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Hemingway, J, Hawkes, N J, McCarroll, L, Ranson, H. The molecular basis of insecticide resistance in mosquitoes. 2004. Insect Biochem Mol Biol, 34, 653-65.

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Pavlidi N, Vontas J, Van Leeuwen T. The role of glutathione S-transferases (GSTs) in insecticide resistance in crop pests and disease vectors. Curr Opin Insect Sci. 2018;27:97-102.

Vontas J, Katsavou E, Mavridis K. Cytochrome P450-based metabolic insecticide resistance in Anopheles and Aedes mosquito vectors: Muddying the waters. Pestic Biochem Physiol. 2020;170:104666.

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