Adipokinetic hormone signaling mediates the enhanced fecundity of Diaphorina citri infected by ' Candidatus Liberibacter asiaticus'

serves as the primary vector for ' Liberibacter asiaticus ( Las),' the bacterium associated with the severe Asian form of huanglongbing. Las-positive are more fecund than their Las-negative counterparts and require extra energy expenditure. Therefore, understanding the molecular mechanisms linking metabolism and reproduction is of particular importance. In this study, we found adipokinetic hormone ( ) and its receptor ( ) were essential for increasing lipid metabolism and fecundity in response to Las infection in . Knockdown of and not only resulted in the accumulation of triacylglycerol and a decline of glycogen, but also significantly decreased fecundity and Las titer in ovaries. Combined in vivo and in vitro experiments showed that miR-34 suppresses expression by binding to its 3' untranslated region, whilst overexpression of miR-34 resulted in a decline of expression and Las titer in ovaries and caused defects that mimicked knockdown phenotypes. Additionally, knockdown of and significantly reduced juvenile hormone (JH) titer and JH signaling pathway genes in fat bodies and ovaries, including the JH receptor, ( ), and the transcription factor, ), that acts downstream of it, as well as the egg development related genes ( ), ( ) and the vitellogenin receptor ( ). As a result, Las hijacks AKH/AKHR-miR-34-JH signaling to improve lipid metabolism and fecundity, while simultaneously increasing the replication of Las, suggesting a mutualistic interaction between Las and ovaries.