First record of Leptopilina japonica Novković & Kimura, 2011 (Hymenoptera: Figitidae) in Germany, a parasitoid of the Spotted Wing Drosophila Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae)

Two years after the first European record in Italy, we report the first occurrence of the parasitoid wasp Leptopilina japonica Novković & Kimura, 2011 (Hymenoptera: Figitidae) in Germany. The species is a larval‐pupal parasitoid of Drosophila suzukii (Matsumura, 1931) (Diptera: Drosophilidae), which is a widespread invasive and economically important pest of soft‐skinned fruit. In total, we found 29 specimens of L. japonica in five different locations in southern and western Germany in the years 2021, 2022 and 2023. We examined the specimens morphologically and generated their DNA barcodes for identification. In three of the locations, L. japonica was sampled from raspberries. In two locations, L. japonica was caught in two and three consecutive years, respectively, which indicates adventive establishment. As D. suzukii and L. japonica originate from the same region in Asia, the possible establishment of L. japonica could be a case of unintentional biological control in Germany. In addition to this first record in Germany, we present a diagnosis of L. japonica to distinguish the species from the rest of the European Leptopilina fauna.

Diapriidae) and Pachycrepoideus vindemmiae (Rondani, 1875) (Hymenoptera: Pteromalidae) (Englert & Herz, 2016;Knoll et al., 2017;Kremmer et al., 2017) and these are currently explored for use in augmentative biological control of SWD in Germany (Eben et al., 2022).European larval-pupal parasitoids of SWD have very low reproduction rates due to host resistance and lead to low levels of mortality of the host (Kruitwagen et al., 2021;Poyet et al., 2013); these species may fail to attack SWD when it is offered as a host (Chabert et al., 2012).
Both species have followed their host to western parts of North America and have been present there since 2016 (L.japonica) and 2019 (G.brasiliensis) (Abram et al., 2020).They have since established adventive populations (Beers et al., 2022).G. brasiliensis is also found in several Central and Southern American countries (Buffington & Forshage, 2016;Gallardo et al., 2022;Gonzalez-Cabrera et al., 2020) and has been released since 2021 as part of a classical biological control programme in Italy (Fellin et al., 2023).
L. japonica is less widely distributed and the only report outside of its area of origin in Southeast Asia (Novković et al., 2011) or North America (Abram et al., 2020) is from Italy in 2019 (Puppato et al., 2020).
In this study, we report the presence of L. japonica in Germany for the first time, which is also the northernmost record of the species in the world.This arrival of L. japonica may open the possibility to enhance natural regulation of SWD in the future.

| MATERIAL S AND ME THODS
We analysed specimens from five different locations in western and southern parts of Germany, details on locations and collection methods are given in Table 1.From three of the locations, wasps were reared from drosophilid-infested berries; in one of them, the berries were exclusively infested by SWD.The collections in Veitshöchheim were conducted to monitor the parasitoid complex of SWD in Germany.
Sequences of the CO1 barcode region were obtained from five specimens (Table 1) using standard procedures at Advanced Identification Methods (AIM, Leipzig, Germany, see Morinière et al., 2015) and the Leibniz Institute for the Analysis of Biodiversity Change (LIB, Museum Koenig Bonn, Germany, see Jafari et al., 2023 for lab protocol, andAstrin &Stüben, 2008 for the LCO1490-JJ forward-and the HCO2198-JJ reverse-primer).We combined our CO1 barcode sequences with those of Leptopilina specimens deposited at the DROP Database (Lue et al., 2021), including the sequences published together with the description of L. japonica (Novković et al., 2011).Using Geneious (vers.7.1.9,Biomatters Ltd.), we aligned sequences with MUSCLE and generated a neighbour-joining tree (Tamura-Nei).Based on this tree, we evaluated conspecificity of the sampled specimens and those with data deposited at DROP on their distance-based clustering.
In addition to CO1 barcode analysis, we morphologically examined barcoded specimens and 24 additional specimens from the same localities using a Leica M205C stereomicroscope.We used the latest treatments of the genus for the Western Palearctic region (Forshage & Nordlander, 2008;Nordlander, 1980;Novković et al., 2011;van Alphen et al., 1991), including the relevant terminology.Our diagnosis of L. japonica is based on information from these sources and verified with specimens of all included taxa, except L. australis (Belizin, 1966), since no specimen of that species was available to us, but which can be distinguished from L. japonica through literature alone.
The result from analysis of the nucleotide sequence data is congruent with the results from the morphological identification.Our sequences match the reference sequences of L. japonica from DROP with 97.8% to 100% similarity (excl.the cluster around the TP strain, since none of our sequences fell within that cluster and the specimens were described as separate subspecies of L. japonica).The minimum similarity among the sequences in the DROP dataset (i.e.alignment without our sequences) is 98.2%.

| DISCUSS ION
The same way that pests spread without intentional human interference, their natural enemies may spread as well (Weber et al., 2021).
In the case of non-native parasitoid Hymenoptera in Europe, 45% originate from unintentional introductions (Weber et al., 2021).
These unintentional introductions may substantially reduce pest populations, as in the case of Aphelinus certus Yasnosh, 1963 (Hymenoptera: Aphelinidae) in the United States (Kaser & Heimpel, 2018), or serve as unintended test area for a later classical biological control programme, as in the case of Trissolcus japonicus (Ashmead, 1904) (Hymenoptera: Scelionidae) in Italy (Falagiarda et al., 2023).
was discovered in 2021 at three different locations up to 220 km apart, it is likely that the species is even more widespread or has been (accidentally) introduced multiple times.In two of the locations, L. japonica was found in consecutive years, which may indicate that adventive populations are established.The specimens in Germany, especially in Bonn, represent, to the authors' knowledge, the northernmost findings of L. japonica (Latitude 50.7).This is possibly due to the mild mesoclimate of the Rhine valley and the favourable conditions in the urban environment.The small number of recorded specimens in this study is linked to the unsystematic type of collecting efforts and probably does not relate to actual population sizes.Although not restricted to the Drosophila melanogaster species group, the known host range of L. japonica is relatively narrow (Daane et al., 2021; Kimura & Novković, 2021; F I G U R E 1 Records of Leptopilina japonica in Germany.F I G U R E 2 (a, b) Leptopilina japonica habitus (lateral view, a) and mesoscutellum (dorsal view, b).The arrows indicate diagnostic characters mentioned in the diagnosis.(c, d) L. heterotoma habitus (lateral view, c) and mesoscutellum (dorsal view, d).