NlCYP4G76 and NlCYP4G115 Modulate Susceptibility to Desiccation and Insecticide Penetration Through Affecting Cuticular Hydrocarbon Biosynthesis in Nilaparvata lugens (Hemiptera: Delphacidae)

The functions of cuticular hydrocarbons (CHCs) are varied in insects, but one example is to reduce water loss. Previous work has suggested that biosynthesis of CHCs is strongly related to the CYP4G sub-family. Targeting these genes in the brown planthopper, Stål, might be a new application for integrated pest management. Therefore, we explored the functions of (GenBank: KM217045.1) and (GenBank: KM217046.1) genes in this study. The desiccation treatment (RH < 5%) for the duration of 1-3 days significantly increased the transcription level of and . RNAi through the injection of and dsRNA could significantly decrease their expression, respectively, and further reduced the biosynthesis of CHCs, i.e., saturated and straight-chain alkanes. When and were suppressed, the susceptibility of nymphs to desiccation increased, due to the deficiency of the CHCs in the insect's cuticle. When the expression of and was decreased, this resulted in an increased rate of penetration of the four insecticides: pymetrozine, imidacloprid, thiamethoxam and buprofezin. Therefore, and appear to regulate the biosynthesis of CHCs in nymphs, which play a major role in protecting insects from water loss and the penetration of insecticides. and might be used as a novel target in integrated pest management to