Effect of parental RNA interference of a transformer-2 homologue on female reproduction and offspring sex determination in Asian citrus psyllid

Asian citrus psyllid Diaphorina citri Kuwayama is the vector of Candidatus Liberibacter asiaticus (CLas), the causal agent of citrus huanglongbing (HLB). A comprehensive understanding of molecular components that govern key physiological traits in D. citri would promote the development of novel genetic control strategies to fight this pest. In the present study, a transformer 2 homologue (Dctra-2) implicated in embryonic sex differentiation in dipteran insects is targeted to interfere with the offspring sex ratio of D. citri. The results of the present study show that Dctra-2 is constitutively expressed at all developmental stages and in both females and males during the adult stage. Quantitative reverse transcriptase-polymerase chain reaction analysis confirms the double-stranded RNA-mediated RNA interference (RNAi) of the Dctra-2. RNAi effects in D. citri female adults can be transferred in a trans-generational manner to their eggs and progeny, which are commonly referred as parental RNAi. RNAi females lay fewer eggs, with a mean of 12.44, and the hatching rate of laid eggs is reduced approximately by 29.86% compared with the control. However, parental RNAi of Dctra-2 do not produce male-biased progeny. The results suggest that Dctra-2 is an effective RNAi target for use in the management of D. citri. In addition, the parental RNAi would provide an effective tool for studying the function of early embryonic genes in D. citri.