Partial elimination of Wolbachia in the Asian citrus psyllid, Diaphorina citri, increases phytopathogen acquisition and decreases fitness.

Wolbachia is a maternally inherited intracellular bacterium that infects a wide range of arthropods. Wolbachia can have a significant impact on host biology and development, often due to its effects on reproduction. We investigated Wolbachia infection in the Asian citrus psyllid, Diaphorina citri, which transmits Candidatus Liberibacter asiaticus (CLas), the causal agent of citrus greening disease. D. citri are naturally infected with Wolbachia; therefore, investigating Wolbachia-mediated effects on D. citri fitness and CLas transmission required artificial elimination of this endosymbiont with application of doxycycline. Doxycycline treatment of psyllids reduced Wolbachia infection by approximately 60% in both male and female D. citri; however, this reduction varied between generations of treated psyllids. Psyllids treated with doxycycline exhibited higher CLas acquisition as both adults and nymphs as compared with negative controls. In addition, doxycycline-treated psyllids exhibited decreased fitness as measured by reduced egg and nymph production as well as adult emergence as compared with controls lines where Wolbachia was not manipulated. Our results indicate that Wolbachia benefits D. citri by improving fitness and potentially competes with CLas by interfering with phytopathogen acquisition. Targeted manipulation of endosymbionts in this phytopathogen vector may yield disease management tools. Importance of the studyThis study provides insights into the critical role of Wolbachia in the Asian citrus psyllid, Diaphorina citri, a known vector of the presumed causal agent of citrus greening disease. Our data indicate a beneficial role of Wolbachia in D. citri, whereby the bacteria greatly enhance overall fitness and affect sex ratio of the host but interfere with acquisition of the phytopathogen, Candidatus Liberibacter asiaticus (CLas). By artificially eliminating Wolbachia from psyllids, the study confirms its endosymbiotic role and opens potential avenues for development of disease control methods. Specifically, our data suggest that targeted manipulation of insect endosymbionts like Wolbachia may potentially contribute new tools for management of this economically devastating and globally widespread disease of citrus.