Intraspecific variability in biocontrol agents: Comparative studies of two strains of Trissolcus japonicus

Intraspecific variability in hymenopteran parasitoids is a well-documented phenomenon of considerable importance to biological control. The samurai wasp, Trissolcus japonicus, is an Asian wasp that is used for biological control of the brown marmorated stink bug, Halyomorpha halys, in Europe and North America. While adventive populations of T. japonicus continue spreading throughout Europe, permission was given to release a T. japonicus line originating from Beijing (China) at more than 700 locations in northern Italy from 2020 onwards. A recent study testing the degree of genetic differentiation among adventive lines and the released Chinese line revealed considerable genetic variation among these lines. Here we present data on differences in life history traits of adventive and released lines and discuss if the level of variability is relevant from a biological control perspective.