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Background: Investigation of insecticide resistance mechanisms is considered a vital first step towards the creation of effective strategies to control resistant mosquitoes and manage mosquito-borne diseases. Our previous study revealed that NYD-OP7 may be associated with deltamethrin resistance in Culex pipiens pallen. However, the precise function of NYD-OP7 in deltamethrin resistance is still unclear. In this study, we investigated the role of NYD-OP7 in the molecular mechanisms underlying pyrethroid resistance., Results: Knockdown of NYD-OP7 not only increased the susceptibility of the mosquitoes to deltamethrin in vivo but also simultaneously repressed both expression and enzyme activity of its downstream effector molecule, phospholipase C (PLC) and expression of several insecticide resistance-related P450 genes. Knockdown of PLC also sensitized the mosquitoes to deltamethrin and reduced the expression of the P450 genes., Conclusions: Our results revealed that NYD-OP7 and its downstream effector PLC contribute to deltamethrin resistance by regulating the expression of P450s in Cx. pipiens pallens.

BACKGROUND The insect cuticle protects against environmental stresses such as insecticides, physical injury, dehydration and pathogenic microorganisms. Structural cuticular proteins (CPs) are the primary components of the cuticle, and are of interest for physiology-based pest management methods. Anopheles sinensis CPs are poorly characterised at present, and therefore we performed whole-genome sequence analysis and re-analysed available transcriptome data to identify potential insecticide resistance-associated CPs. RESULTS Genome analysis revealed 238 putative CPs belonging to 11 different families; 136 proteins possessing a Rebers and Riddiford motif (CPR), 12 CPs analogous to peritrophins with a single chitin-binding domain (CPAP1), eight CPs analogous to peritrophins with three chitin-binding domains (CPAP3), four proteins with a 44 amino acid motif (CPF), five CPF-like (CPFL) proteins, nine Tweedle proteins, three proteins of low complexity with alanine residues (CPLCA), 26 proteins of low complexity with conserved glycine residues (CPLCG), seven proteins of low complexity with invariant W residues (CPLCW), 27 proteins of low complexity with proline residues (CPLCP), and one protein with two or three copies of a C-X -C motif (CPCFC). Two CPs belonging to the CPR and CPAP3 families were over-expressed in a deltamethrin-resistant strain. CONCLUSION These results establish an information framework for An. sinensis CPs that provides a basis for further molecular research. © 2017 Society of Chemical Industry [ABSTRACT FROM AUTHOR]