Microbiome of psyllids of the family Aphalaridae, includingAphalara itadori, a potential biocontrol agent againstReynoutriaspp

Abstract

AbstractSeveral European and North American countries have started releasing the Japanese knotweed psyllidAphalara itadori(Hemiptera: Aphalaridae) to control the Japanese knotweedReynoutria japonica(Caryophyllales: Polygonaceae) and its relatives, which are among the worst invasive exotic plants. However, establishing populations of the current Kyushu and Hokkaido strains in the field has not been successful, desiring new lineages. Moreover, little is known about the microbiome of the current strains, which potentially impacts properties as biocontrol agents. Hence, this study analyzed the microbiota of anA. itadoristrain newly collected on Honshu Island, along with related species of the family Aphalaridae, using amplicon sequencing of 16S rRNA genes. TheA. itadorisymbionts were further located using fluorescencein situhybridization. The results demonstrated that the analyzedA. itadoristrain has a dual symbiotic system with “CandidatusCarsonella ruddii” (Gammaproteobacteria: Oceanospirillales) andSodalissp. (Gammaproteobacteria: Enterobacterales) harbored in the bacteriome, suggesting their evolutionarily stable mutualistic relationships withA. itadori. The central area of the bacteriome harboringSodalisappeared to comprise uninucleate bacteriocytes with nuclei larger than those of bacteriocytes forCarsonella, rather than a syncytium with smaller nuclei as previously reported for various psyllid lineages. No known plant pathogens or manipulators of insect reproduction were identified in the analyzed strain, indicating its suitability as a biocontrol agent, posing a minimum risk to the ecosystem. Besides distinctCarsonellalineages, the analysis identifiedSodalisindependently acquired byCraspedolepta miyatakeai, and an ambiguousEnterobacteralessymbiont inEpheloscyta kalopanacis. OnlyCarsonellawas identified inTogepsylla matsumurana.