Neuropeptide ecdysis-triggering hormone and its receptor mediate the fecundity improvement of ‘Candidatus Liberibacter asiaticus’-infected Diaphorina citri females and CLas proliferation

The severe Asiatic form of huanglongbing (HLB), caused by “Candidatus Liberibacter asiaticus” (CLas), threatens global citrus production via the citrus psyllid, Diaphorina citri. Culturing challenges of CLas necessitate reducing D. citri populations for disease management. CLas boosts the fecundity of CLas-positive (CLas+) D. citri and fosters its own proliferation by modulating the insect host's juvenile hormone (JH), but the intricate endocrine regulatory mechanisms remain elusive. Here, it is reported that the D. citri ecdysis-triggering hormone (DcETH) and its receptor DcETHR play pivotal roles in the reciprocal benefits between CLas and D. citri within the ovaries, influencing energy metabolism and reproductive development in host insects; miR-210, negatively regulates DcETHR expression, contributing to this symbiotic interaction. CLas infection reduces 20-hydroxyecdysone (20E) levels and stimulates DcETH release, elevating JH production via DcETHR, enhancing fecundity and CLas proliferation. Furthermore, circulating JH levels suppress 20E production in CLas+ ovaries. Collectively, the orchestrated functional interplay involving 20E, ETH, and JH increases energy metabolism and promotes the fecundity of CLas+ D. citri and CLas proliferation. These insights not only broaden the knowledge of how plant pathogens manipulate the reproductive behavior of insect hosts but also offer novel targets and strategies for combatting HLB and D. citri.