Biocontrol implications of multiparasitism by <i>Trissolcus mitsukurii</i> and <i>Trissolcus japonicus</i> on the invasive brown marmorated stink bug

The egg parasitoids Trissolcus japonicus (Ashmead) and mitsukurii (Hymenoptera: Scelionidae) are the most effective biocontrol agents of invasive agricultural pest Halyomorpha halys (Stål) (Heteroptera: Pentatomidae) in its native range (east Asia). T. sympatric areas. In northern Italy, where H. is a major fruit orchards, adventive populations both species spreading, artificially released under classical program against halys. This laboratory study aimed to assess outcome competition when share same resource possible implications for biological control stink bug. Egg masses were offered each parasitoid after previous parasitization by other species. Parasitoid behaviour, number ovipositions, successfully developed recorded. Additionally, contest behaviour was assessed simultaneously on mass. Results showed that able parasitize an mass already parasitized Competition occurred within host eggs outperformed it first oviposit. Importantly, overall contribution mortality not affected interaction between parasitoids, as non-parasitized 4–6% absence <8% presence, respectively. When mass, more aggressive, engaging chase-off events 71% cases compared 50% japonicus.