First report of Trissolcus japonicus, an egg parasitoid of Halyomorpha halys, in Europe
Halyomorpha halys (Hemiptera: Pentatomidae – formerly EPPO Alert List) originates from Asia and has emerged as an invasive pest in North America and Europe in the 1990s and 2000s, respectively. Surveys conducted in Northeastern China (part of the native range) have shown that the dominant parasitoid of H. halys was Trissolcus japonicus (Hymenoptera: Scelionidae – egg parasitoid), with parasitism levels ranging from 50 to 90%. Therefore, this species has been considered as a classical biological control agent in invaded areas. In Switzerland, a survey of native egg parasitoids of H. halys conducted in 2017 and 2018 revealed that T. japonicus was already present in apple orchards in the Canton Ticino. T. japonicus was recovered from sentinel egg masses of H. halys at 3 different sites and during 2 consecutive years, suggesting that it is established in Switzerland. Although further studies are needed to follow the establishment and spread of T. japonicus, as well as to evaluate its impact on H. halys and eventually on non-target pentatomid populations. it is hoped that T. japonicus will have the potential to reduce the populations of H. halys below economic thresholds.
Interestingly, a similar situation occurred in the USA, where T. japonicus was unexpectedly found in 2014 in Beltsville (Maryland) during a study on native egg parasitoids of H. halys.
Note: a nice video of Trissolcus japonicus parasitizing eggs of H. halys can be viewed on the Internet: https://www.youtube.com/watch?v=rbdXiiM538I
Sources
Stahl J, Tortorici F, Pontini M, Bon MC, Hoelmer K, Marazzi C, Tavella L, Haye T (2018) First discovery of adventive populations of Trissolcus japonicus in Europe. Journal of Pest Science. https://doi.org/10.1007/s10340-018-1061-2
Talamas EJ, Herlihy MV, Dieckhoff C, Hoelmer KA, Buffington ML, Bon M-C, Weber DC (2015) Trissolcus japonicus (Ashmead) emerges in North America. Journal of Hymenoptera Research 43, 119-128. https://doi.org/10.3897/JHR.43.4661