Knockdown of hexokinase in Diaphorina citri Kuwayama (Hemiptera: Liviidae) by RNAi inhibits chitin synthesis and leads to abnormal phenotypes

Background Silencing specific genes in pests using RNA interference (RNAi) technology is a promising new pest‐control strategy. The Asian citrus psyllid, Diaphorina citri Kuwayama, is the most important citrus pest because it transmits Candidatus Liberibacter asiaticus, which causes huanglongbing. Chitin is essential for insect development, and enzymes in this pathway are attractive targets for pest control. Results The hexokinase gene DcHK was characterized from D. citri to impair proper growth and chitin synthesis through RNAi. The transcription of DcHK was more highly developed in third‐instar nymphs, adults and the Malpighian tube. The RNAi needed for D. citri is dose‐dependent, with 600 ng μl−1 dsDcHK sufficient to knockdown endogenous DcHK expression. The messenger RNA (mRNA) level was lowest at 36 h after dosing, and there were significant effects on the relative levels of mRNA in the chitin synthesis pathway (DcTre, DcG6PI, DcGNAT, DcGFAT, DcPGM, DcUAP and DcCHS), leading to mortality, reduced body weight and abnormal or lethal phenotypes. Conclusion RNAi can be triggered by orally delivered double‐stranded RNA in D. citri. These results can provide support for HK genes as a new potential target for citrus psyllid control. © 2022 Society of Chemical Industry.