Compatibility of released and adventive populations of Ganaspis kimorum Buffington, 2024, (Cynipoidea, Figitidae), parasitoid of the spotted-wing drosophila Drosophila suzukii (Matsumura, 1931)

Abstract

Taxonomic and host associations have been closely studied within the Ganaspis brasiliensis (Ihering, 1905) (Hymenoptera, Figitidae) complex as parasitoids of the spotted-wing drosophila, Drosophila suzukii (Matsumura, 1931) (Diptera, Drosophilidae). Initially, five genetic groups (G1–G5) were identified that suggested the existence of cryptic species that vary in their host ranges and geographic distributions. What was referred to as the “G1” strain was recently described as G. kimorum Buffington, 2024, and approved for release as a classical biological control agent in the United States and parts of Europe. Concurrently, an adventive population of G. kimorum was found in British Columbia, Canada and is likely spreading through parts of the Pacific Northwest such as Washington State, USA. Here, we compare the reproductive compatibility and molecular similarity of laboratory-bred G. kimorum (collected in Tokyo, Japan) used for release in the USA and Europe with the adventive population found in Washington State, USA. Cross-breeding experiments between the Tokyo and the adventive population showed successful mating and the production of female offspring, indicating that they are reproductively compatible. For both populations, the mitochondrial COI barcode region was sequenced and further confirmed the conspecificity of the Tokyo and adventive Washington populations with published G. kimorum. These findings will help to better understand and document the effects of releases of G. kimorum and the reproductive success of adventive and released populations.