Effect of silencing a boule homologue on the survival and reproduction of Asian citrus psyllid Diaphorina citri

The fertility gene boule is conserved in most organisms and deletion of boule is found to block meiosis during spermatogenesis, which contributes to male infertility. The biological role of boule in Asian citrus psyllid Diaphorina citri, currently the most serious citrus pest and the vector of huanglongbing (HLB) pathogen, remains poorly understood. In the present study, a boule homologue in Diaphorina citri (DcBol) is identified and the potential application of DcBol for RNA interference (RNAi) based control of D. citri is evaluated. DcBol is constitutively expressed at gonadal and somatic tissues in both sexes. DsDcBol appears to be refractory to the salivary proteins of D. citri and no degradation is discovered over a 3-day feeding period. DsRNA-mediated RNAi of DcBol is achieved via artificial feeding, with DsDcBol at 400 ng mu L-1 being sufficient to knockdown endogenous DcBol expression. A further bioassay reveals that knockdown of DcBol causes higher mortality of adult D. citri. In comparison with the control, the number of eggs and offspring nymphs generated by RNAi males is not reduced significantly. The results of the present study indicate that DcBol may play a limited role in male fertility.