Host range of Trissolcus japonicus
Halyomorpha halys (Hemiptera: Pentatomidae – formerly EPPO Alert List) originates from Asia and emerged as an invasive pest in North America and Europe in the 1990s and 2000s, respectively. Trissolcus japonicus (Hymenoptera: Scelionidae – an egg parasitoid) is a biological control agent of H. halys which has been unintentionally introduced into the EPPO region with adventive populations occurring in some countries (e.g. Germany, Italy and Switzerland). Host specificity testing has shown that the physiological host range (the range of species on which T. japonicus can survive, reproduce and complete its lifecycle under optimum conditions) is reasonably broad. To assess if the predicted physiological host range was similar to the realized host range (the range of species on which a BCA is able to survive, reproduce and complete its life cycle under natural conditions in the field) sentinel egg masses of H. halys along with 18 native non-target species (Pentatomidae and Scutelleridae) were exposed to T. japonicus in Italy and Switzerland. Additionally, naturally occurring egg masses were also assessed. Over the three-year study, 15 of the 18 non-target species were recorded to be parasitized by T. japonicus though in most case the parasitism was less on non-targets compared to H. halys. Pentatoma rufipes was the non-target species most parasitized by T. japonicus and reasons for this include sharing the same ecological niche as H. halys and that P. rufipes lays eggs in the late summer when parasitism by T. japonicus is at its highest.
Sources
Haye T, Moraglio ST, Tortorici F, Marazzi C, Gariepy TD, Tavella L (2023) Does the fundamental host range of Trissolcus japonicus match its realised host range in Europe? Journal of Pest Science. https://doi.org/10.1007/s10340-023-01638-0