First records of adventive populations of the parasitoids Ganaspis brasiliensis and Leptopilina japonica in the United States

Abstract

We report the first known incidence of two parasitoid species of the invasive pest, Drosophila suzukii (Matsumura) (Diptera: Drosophilidae), in the United States (US). The discovery of Ganaspis brasiliensis (Ihering) (Hymenoptera: Figitidae) and Leptopilina japonica (Novković & Kimura) (Hymenoptera: Figitidae) in northwestern Washington State (US) was made shortly after their discovery in nearby southwestern British Columbia (Canada), indicating that contiguous populations of these species are established in both countries. The first specimen of L. japonica from Washington was collected in the fall of 2020, when it was found in a rice wine/orange juice trap deployed to survey for Vespa mandarinia Smith (Hymenoptera: Vespidae). Subsequent examination of trap contents from the 2020–2021 seasons indicated the presence of both L. japonica and G. brasiliensis. In September of 2021, live collections of both G. brasiliensis and L. japonica were made, reared from D. suzukii-infested Himalayan blackberry in Whatcom County, WA. Adult parasitoid identifications were based on morphology and COI DNA barcodes. All sequenced specimens to date from Washington and British Columbia belong to the G1 group of G. brasiliensis, the only group approved for release as a classical biological control agent in the US. This study provides an example of how even small changes in the geographic range of a natural enemy, now extending across an international border, may have significant consequences for the future of a biological control program.

Olfactory responses of Drosophila suzukii parasitoids to chemical cues from SWD-infested fruit

“…In fact, inundative biological control is currently applied against D. suzukii in Europe, where Trichopria drosophilae (Hymenoptera: Diapriidae) is the most promising and commercially available biocontroler (Gonzalez-Cabrera et al, 2019; Rossi-Stacconi et al, 2018). In the United States, as a result of quarantine studies in Switzerland and California (US), and given the specificity shown by the Ganaspis brasiliensis (Hymenoptera: Figitidae) groups, a petition submitted to USDA-APHIS was approved for the release of G. brasiliensis G1 group (Beers et al, 2022). Trichopria anastrephae has been proposed in Brazil as useful in greenhouses (Vieira et al, 2020).…”

Ovipositor characteristics differ between two parasitoids (Hymenoptera, Figitidae) of Drosophila suzukii (Diptera, Drosophilidae) in an adventive landscape

“…The narrow host range of G. brasiliensis has led to its recent approval for field release in the United States of America (Beers et al 2022). Leptopilina japonica, however, has not yet been approved for release in the USA due to its broader host range.…”

“…Two parasitoid wasp species, Leptopilina japonica Novković & Kimura and Ganaspis brasiliensis Ihering (Hymenoptera: Figitidae), have been proposed as candidate classical biological control agents for the small fruit pest D. suzukii (Lee et al 2019). These parasitoids have recently been detected in North America, specifically in southwestern British Columbia (BC), Canada (Abram et al 2020) and northwestern Washington State, USA (Beers et al 2022). Leptopilina japonica has the broader host range of the two parasitoids and successfully parasitizes several drosophilid species in four genera in laboratory trials (Kimura and Novković 2015;Girod et al 2018b;Daane et al 2021).…”

“…Leptopilina japonica has the broader host range of the two parasitoids and successfully parasitizes several drosophilid species in four genera in laboratory trials (Kimura and Novković 2015;Girod et al 2018b;Daane et al 2021). The lineage of G. brasiliensis recorded in BC and Washington State ("G1"; Beers et al 2022) has a narrower host range, primarily attacking flies in the subgenus Sophophora Sturtevant in laboratory trials (Girod et al 2018b;Giorgini et al 2019;Daane et al 2021). These parasitoids are adventive in the fruit growing regions of southwestern BC but have evidently not dispersed into the province's interior (Abram et al 2022a, b).…”

Mapping the global distribution of invasive pest Drosophila suzukii and parasitoid Leptopilina japonica: implications for biological control

“…In its native distributional areas, L. japonica is one of most abundant potential parasitoids of D. suzukii ( Kimura & Novković, 2015 ; Puppato et al, 2020 ); its occurrence in Europe( Puppato et al, 2020 ) and North America ( Abram et al, 2020 ; Abram et al, 2022 ; Beers et al, 2022 ) was identified only recently. Previous laboratory experiments in the United States indicated that South Korean L. japonica strains attacked the North American strains of D. suzukii readily ( Daane et al, 2016 ), supporting at least in part the suitability of L. japonica as a biocontrol agent for D. suzukii .…”