Silencing of Cytochrome P450 genes CYP6CY14 and CYP6DC1 in Aphis gossypii by RNA interference enhances susceptibility to clothianidin

Cytochrome P450s (CYPs) genes are associated with insecticide resistance through overexpression and detoxification mechanisms in several insect-pest species. However, little is known about the role of P450s genes and their response to clothianidin resistance development in cotton-melon aphid, Aphis gossypii, a serious crop pest. In this study, we characterized CYP6CY14 and CYP6DC1 from CYP3 clad that are differentially expressed in aphids. Quantitative real-time PCR (qRT-PCR) analyses revealed that CYP6CY14 and CYP6DC1 expressions were significantly higher among thirty five cytochrome P450 genes in clothianidin-resistant strain (CT-R) of A. gossypii compared to the susceptible strain (CT-S). RNAi was conducted to knock-down the highly expressed CYPs genes (CYP6CY14 and CYP6DC1 from CYP3 clad) and study their detoxification effects on clothianidin. The apterous adult aphids became more sensitive to clothianidin, with a higher mortality rate than the control after silencing CYP6CY14 and CYP6DC1 genes. Bioinformatic analysis showed conserved motifs in amino acid sequences of CYP6CY14 and CYP6DC1 with other insect species. This study highlighted the functional importance of these P450 genes in insecticide resistance development and revealed that overexpression of CYP6CY14 and CYP6DC1 genes was responsible for the high levels of insecticide resistance in the A. gossypii population.