Population incompatibility associated with Wolbachia in the Asian citrus psyllids, Diaphorina citri: insights for pest management

BACKGROUND: Wolbachia are the most common intracellular symbiont in invertebrates primarily found in the reproductive tissues of their hosts inducing various host phenotypes such as cytoplasmic incompatibility (CI) that can affect their persistence and spread in host populations. This study explores the presence and likely impact of Wolbachia bacteria in the Asian citrus psyllid (ACP), Diaphorina citri. RESULTS: We detected Wolbachia in populations of ACP collected from Roodan (Ro) and Jahrom (Ja) in Iran and quantified their titers in different stages and tissues. Wolbachia titers were higher in the Ja population than the Ro population across stages and tissues. In both populations Wolbachia showed perfect vertical transmission. Based on the ftsZ gene, ACP Wolbachia belong to supergroup B. Using tetracycline treatment, we eliminated Wolbachia from ACP adults. However, the cured insects did not breed, preventing the establishment a Wolbachia-free line. We also crossed the Ja and Ro populations reciprocally and surprisingly found that the resultant eggs did not hatch although crosses of males and females within populations showed normal hatching. This suggests a bidirectional CI phenotype, likely as a result of different Wolbachia infections in the two populations. To test Wolbachia divergence further, we used quantitative polymerase chain reaction high-resolution melting analysis targeting the ftsZ gene followed by ftsZ sequence analysis, which revealed differences in the Wolbachia strains from the two ACP populations. To characterize the reproductive phenotype further and consider its potential use to suppress ACP populations, we varied the proportions of males and females from the different populations and released them on lemon seedlings where hatch rates were recorded. The hatch rates varied from 84.85 ± 1.8% in populations with an equal number of ♀ and ♂ from the Ro population to a low of 2.02 ± 1.7% where there was a ratio of 1:1:10 (♀Ro:♂Ro:♂Ja) present, reflecting the expected strong bidirectional CI when Ja males were released at a high relative frequency into an Ro population. CONCLUSION: Together, these results suggest that Wolbachia strains with perfect vertical transmission may induce strong population-level bidirectional CI with potential use for suppression of ACP populations. © 2025 Society of Chemical Industry.