Effects of vector-borne plant pathogen on interactions between Diaphorina citri and its natural enemy, Harmonia axyridis

The Asian citrus psyllid, Diaphorina citri, is the vector of plant pathogen, Candidatus Liberibacter asiaticus (CLas) that causes huanglongbing, also known as citrus greening disease. This pathogen can manipulate vectors directly by modifying their behavior and fitness and indirectly by reducing host plant quality, which could also affect predation by natural enemies in the third trophic level. The objective of this study was to understand how CLas affects the interactions between D. citri and its predators. We compared fitness of Harmonia axyridis fed on non-infected versus CLas-infected adult psyllids in no-choice bioassays by measuring feeding rates and weight of male and female beetles. Furthermore, we quantified egg laying and oocyte development in beetles fed on infected versus non-infected psyllids. Our results support the hypothesis that D. citri carrying the CLas pathogen are a sub-optimal food source as compared with non-infected counterparts, which may impact fitness of predators.