Gut-binding peptides as novel tools to block Candidatus Liberibacter asiaticus (CLas) transmission by Diaphorina citri

The Asian citrus psyllid (ACP), Diaphorina citri Kuwayama, transmits the bacterium Candidatus Liberibacter asiaticus (CLas), which is presumed to cause huanglongbing (HLB) or citrus greening. Psyllid management with chemical insecticides has led to the emergence of resistant populations and negatively impacted non-target organisms. The aim of this research is to identify alternative strategies to reduce CLas spread and reinfection by disrupting ACP-mediated transmission. Gut-binding peptides (GBPs) are potential agents for blocking transmission of circulative, propagative pathogens by insect vectors. Here, we investigated whether GBPs could be used to disrupt the association of CLas with the D. citri gut epithelium, potentially interfering with transmission. We used an immobilized droplet feeding assay (IDFA) and membrane feeding to evaluate the effect of GBPs on CLas acquisition by ACP nymphs and adults, respectively. Our results indicate that certain GBPs significantly reduced CLas acquisition and inoculation by D. citri compared with controls. Moreover, D. citri nymphs fed with some GBPs exhibited lower CLas infection rates in their alimentary canal and salivary glands following acquisition access periods. Furthermore, GBPs did not affect D. citri fecundity or development, but slightly increased mortality compared to controls. These promising initial results suggest that GBPs may offer an alternative and environmentally conscious approach to inhibiting CLas transmission by ACP vectors.