The intense use of insecticides has resulted in the selection of resistance in mosquitoes and agricultural pests to such an extent that their control becomes exceedingly challenging. Target site mutations or increased detoxification are the major mechanisms responsible for the phenotype, however it is often their co-evolution that leads to striking resistance phenotypes. By using a variety of approaches, including immunohistochemical staining, functional expression, and characterization of recombinant P450 proteins, as well as in vivo ectopic expression and CRISPR-mediated genome modification in Drosophila, we aim to understand better the role of individual genes and pathways in the development of resistance. Immunohistochemical stainings showed that the major pyrethroid P450 metabolizers in the main malaria vector Anopheles gambiae, such as the CYP6M2, CYP6Z1, and CYP6Z2 are primarily localized in the malpighiam tubules. We have also expressed a number of P450s from the spider mite Tetranychus urticae that were associated with striking multiple resistance phenotypes, such as tuCYP392E10, tuCYP392A16, and tuCYP392A11 and have verified that they are capable of catalyzing the detoxification of certain acaricides/insecticides, such as tetronic acids, avermectins, and METIs. We currently evaluate P450 genes and mutations associated with insecticide resistance, via ectopic expression and genome modification, in Drosophila. We employ the GAL4/UAS system for ectopic expression of cytochrome P450s and the CRISPR system for the introduction of several resistance mutations in Drosophila and assay phenotypes with predicted resistance to different pesticides.

Functional, immunohistochemical, and targeted mutagenesis/ectopic expression approaches for understanding the role of individual genes and pathways in insecticide resistance

248th National Meeting (2014)

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