First records of Ctenochares bicolorus (Linnaeus, 1767) (Hymenoptera: Ichneumonidae) in Germany

35 FAUNISTISCH-ÖKOLOGISCHE MITTEILUNGEN 13/2024 KIEL-UP • DOI: 10.38072/2699-7762/p26 First records of Ctenochares bicolorus (Linnaeus, 1767) (Hymenoptera: Ichneumonidae) in Germany Erste Nachweise von Ctenochares bicolorus (Linnaeus, 1767) (Hymenoptera: Ichneumonidae) in Deutschland Lennart Bendixen 1, Niklas Büchel2, Jörg Tilmans3, Thomas Hörren 4, Augustijn De Ketelaere 5, Fons Verheyde 6 1 Mohrkirch, lennar[email protected] 2 Köln 3 Mönchengladbach 4 Essen 5 Beernem (Belgium) 6 Oostende (Belgium) Schlüsselwörter: eingeschleppte Art, Faunistik, parasitoide Wespen Zusammenfassung Die Schlupfwespe Ctenochares bicolorus (Linnaeus, 1767) wird erstmals in Deutschland nachgewiesen, basierend auf einem im Mai 2023 in einem Kölner Supermarkt fotografierten Weibchen und einem im Dezember 2023 in einem Mönchengladbacher Wohnzimmer gefangenen Männchen. Abstract The ichneumonine Darwin wasp Ctenochares bicolorus (Linnaeus, 1767) is reported for the first time from Germany based on a female photographed in May 2023 in a Cologne supermarket and a male caught in December 2023 in a living room in Mönchengladbach. Keywords: Introduced species, faunistics, parasitoid wasps 1. Introduction Ctenochares bicolorus, a well-known African species introduced to Southern Europe, has been recorded from Northwest Europe only recently, namely from England (Jones 2001), Belgium and the Netherlands (Verheyde 2019). Ctenochares Förster, 1868 is a small genus more or less confined to the African continent (Yu et al. 2016), of which only C. bicolorus is a resident of Continental Europe. In May 2023, a conspicuous female ichneumonid sitting on cauliflower was photographed by NB in a “Rewe” supermarket in Cologne. The image was uploaded to iNaturalist, later determined as ichneumonid by another user and hence was found by LB while scanning German records of ichneumonids on citizen science platforms. In December 2023, a male of the same species was found by JT in his living room after returning from a supermarket. It was uploaded to Naturgucker.de and Observation.org, where it was identified by the AI as Ctenochares bicolorus. The male specimen was handed over to TH in a container with some sugar water the day after the record where it lived for another 21 days. 13/2024 FAUNISTISCH-ÖKOLOGISCHE MITTEILUNGEN KIEL-UP • DOI: 10.38072/2699-7762/p26 36 Bendixen et al.: First records of Ctenochares bicolorus (Linnaeus, 1767) (Hymenoptera: Ichneumonidae) in Germany 2. Materials & Methods The female specimen was photographed in-situ by NB using an iPhone 13 mini. The image was uploaded to iNaturalist.com and can be found here: https://www. inaturalist.org/observations/161387157 (last accessed December 3, 2024). The male specimen was photographed in a plastic box by JT using a Panasonic DC-TZ202D and flashlight. The images were uploaded to Naturgucker and observation.org and can be found at https://naturgucker. de/?bild=-176285818 (last accessed December 3, 2024) and https://observation.org/observation/294800844/ (last accessed December 3, 2024). The specimen was given to Thomas Hörren and is now deposited in the collection of the Entomologischer Verein Krefeld. To make sure no records were missed, all unseen German records of ichneumonids on Naturgucker.de and Observation.org and all Central European records of ichneumonids on iNaturalist were checked during the winter of 2023/2024 by LB. Here, Central Europe is defined in the sense of Jordan’s (2005) country-based division of Europe, including Germany, Luxembourg, Switzerland, Liechtenstein, Austria, Slovenia, Croatia, Hungary, Slovakia, Czechia, Poland, Lithuania, Latvia and Estonia. 3. Results The female from Köln was identified as Ctenochares bicolorus (Linnaeus, 1767) by LB. The male from Mönchengladbach was identified by the app “ObsIdentify” as the same species and was validated by ADK. These are the first records from Germany known to us and at the same time possibly the first from Central Europe. Recognition From photos, the species can be easily recognised on its habitus and colours: with the tricoloured flagellum and black/red mesosoma with orange scutellum, combined with the conspicuously darkened fore wing tip and apical metasomal tergites, C. bicolorus is hardly to be mistaken for any other species. Another helpful character is the slender appearance with the metasoma protruding conspicuously beyond the tip of the forewing. The equally conspicuous but larger Callajoppa exaltatoria (Panzer, 1804) can be distinguished from C. bicolorus by a mainly black mesoscutum, black propodeum, lack of a white antennal ring, less distinct infuscation of the forewing tip and stouter body shape. With a specimen at hand, the lack of any propodeal carination combined with the pectinate claws are distinctive (Gauld 1984), although Heinrich (1967) points out that the degree of pectination of the claws underlies considerable variation and is not always well visible. Gauld (1984) and Verheyde (2019) describe additional characteristics. Observation.org’s AI identified the male specimen discussed here correctly. Concerning ichneumonids, this tool is mainly ‘trained’ by FV’s and ADK’s approximately 230.000 Belgian and Dutch validated records (partially available on GBIF). This finding proves the AI works well for many of the more easily recognisable species, even if only few pictures (in this case approx. 10) are available. Because of the automatic labelling, the record of the male C. bicolorus could be detected quickly and thus validated without much effort. This approach, of course, involves the risk of overlooking records not identified correctly by the AI or only to family level, as happened to the female uploaded to iNaturalist, which was probably too small in relation to the photo size to be recognised by iNaturalist’s AI as C. bicolorus. Fig. 1: Female Ctenochares bicolorus in a Cologne supermarket, 13th of May 2023, Köln, Germany. Photo (cropped) Niklas Büchel. Bendixen et al.: First records of Ctenochares bicolorus (Linnaeus, 1767) (Hymenoptera: Ichneumonidae) in Germany 37 FAUNISTISCH-ÖKOLOGISCHE MITTEILUNGEN 13/2024 KIEL-UP • DOI: 10.38072/2699-7762/p26 Fig. 3: Male Ctenochares bicolorus, 18th of December 2023, Mönchengladbach, Germany. Photo Jörg Tilmans. Fig. 2: Male Ctenochares bicolorus, 18th of December 2023, Mönchengladbach, Germany. Photo Jörg Tilmans. 4. Discussion Biology The supposed main host of C. bicolorus is the polyphagous plusiine moth Chrysodeixis chalcites (Esper, 1789) (Lepidoptera: Noctuidae) (Fitton et al. 1983), which is distributed from Southern Europe to Southern Africa. With the help of southerly winds, adults from the Mediterranean occasionally migrate to Central and Northern Europe (Collins et al. 2014) but the species is more often introduced to Germany as larva with its food plants (Steiner et al. 2014). In the Netherlands, C. chalcites can be very common in greenhouses where it mainly feeds on Tomato (Verheyde 2019). It is not yet known to reproduce in the wild in Germany but has recently been reported to do so in South Tirol (Eitschberger & Frei 2019). The related plusiine moth Autographa gamma (Linnaeus, 1758), a known host of C. bicolorus in Malta (Mifsud et al. 2019), however, is one of the commonest moths in Germany. Thus, it is not impossible that C. bicolorus will be able to establish populations in Central Europe in the future. In the Netherlands, the species has already been found “in the wild” (although in an urban environment) as early as 2018 (https:// waarneming.nl/observation/157152942/, last accessed December 3, 2024). Distribution Whilst other members of the genus are largely confined to sub-Saharan Africa, C. bicolorus shows an unusually wide distribution from Southern Africa to Southern Europe, which led to several descriptions of the species in various genera (Heinrich 1967). Guérin-Méneville (1848, as Ichneumon instructor F.) was already aware of its occurrence in both Cape of Good Hope and Sicily without expressing any doubts that these records refer to the same species. Apart from this, Berthoumieu (1894) was the first to mention occurrences on the European continent, namely in Italy, Greece, France and Spain. Fitton et al. (1983) considered the species migratory, thus, with the potential of reaching Southern Europe by itself. In contrast, Verheyde (2019) regarded it as introduced. So far, it remains unresolved whether C. bicolorus has colonised the European Mediterranean with or without human aid in the 19th century. The species is considered introduced to Australia and New Zealand, where it was recorded since 1970 (Gauld 1984) and 1981 (Fitton et al. 1983), respectively. Recent expansion in Europe Although Schmiedeknecht (1930) included the species in his key to the Hymenoptera of North and Central Europe (as C. instructor (Fabricius, 1793)), it was probably only known from Greece, Italy, France and Spain at 13/2024 FAUNISTISCH-ÖKOLOGISCHE MITTEILUNGEN KIEL-UP • DOI: 10.38072/2699-7762/p26 38 Bendixen et al.: First records of Ctenochares bicolorus (Linnaeus, 1767) (Hymenoptera: Ichneumonidae) in Germany that time (Meyer 1933). More northerly located records stem from London in 2000 (Jones 2001), the Netherlands in 2015 and 2018 and Belgium in 2019 (Verheyde 2019). Since then, more recordings of the species were reported for both countries and it has also been reported in Denmark, Sweden, Norway and Scotland within the last two years (www.inaturalist.org/observations?- place_id=any&subview=map&taxon_id=343394). This suggests that C. bicolorus has been becoming more commonly spread with vegetable transports (cf. Verheyde 2019). This is supported by the fact that most of the specimens were found in vegetables (cauliflower, endive and spinach), and a good share of them late in the year (December) indoors and in bigger cities. However, as the numbers of records from these countries on citizen science portals are generally increasing, it remains uncertain whether human-assisted introductions are the only cause for the species’ more frequent observations in Europe. 5. Conclusions and prospects The here reported records of C. bicolorus from Germany are strongly believed to result from unintentional introductions with vegetables. Thus, the species is not considered to reproduce in Germany and should consequently neither be regarded as part of the German fauna nor be added to the checklist of German ichneumonids (Riedel et al. 2021). Such an addition of C. bicolorus to the checklist may be reconsidered, should its sightings increase, especially in the wild. Acknowledgements Many thanks to Alexandra Viertler for helpful comments on the manuscript. Author Lwennart Bendixen Lennart Bendixen is an entomologist with a main interestin faunistics and ecology of Western Palaearctic Ichneumonidae. / Lennart Bendixen ist Entomologe mit Interessenschwerpunkt auf der Faunistik und Ökologie westpaläarktischer Ichneumoniden. Fig. 4: Female Ctenochares bicolorus in a Cologne supermarket, 13th of May 2023, Köln, Germany. Photo Niklas Büchel. Bendixen et al.: First records of Ctenochares bicolorus (Linnaeus, 1767) (Hymenoptera: Ichneumonidae) in Germany 39 FAUNISTISCH-ÖKOLOGISCHE MITTEILUNGEN 13/2024 KIEL-UP • DOI: 10.38072/2699-7762/p26 References Berthoumieu V (1894) Ichneumonides d’Europe et des pays limitrophes. Annales de la Société Entomologique de France 63:505-592. Collins L, Korycinska A, Baker R (2014) Rapid Pest Risk Analysis for Chrysodeixis chalcites. 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