Can native egg parasitoids adopt the invasive brown marmorated stink bug, Halyomorpha halys (Heteroptera: Pentatomidae), in Europe?

Halyomorpha halys was accidentally introduced into Switzerland around 2004 and has recently spread to several additional areas in Europe, with established populations documented in France, Italy, Greece and Hungary. To test whether generalist egg parasitoids of European Pentatomidae have the potential to control H. halys, and whether these could be as effective as their related Asian species, sentinel egg masses of H. halys and six native European pentatomids were exposed in two regions of Switzerland. Freeze-killed sentinel egg masses of H. halys were attacked by the platygastrid Trissolcus cultratus and the eupelmid Anastatus bifasciatus, whereas fresh egg masses of native Pentatomidae occassionally yielded four Scelionidae species: Trissolcus semistriatus, T. scutellaris, T. cultratus and Telenomus chloropus. In no-choice tests, T. chloropus and T. semistratus produced no offspring from fresh H. halys eggs, whereas T. cultratus and T. scutellaris were sporadically able to complete development. Stopping embryogenesis by freezing egg masses of H. halys at -80 °C enabled T. cultratus and T. semistriatus to produce a high number of offspring without influencing the behaviour of the parasitoids. In contrast to European platygastrids, the Asian parasitoids Trissolcus japonicus and T. cultratus (Chinese strain) caused significantly higher parasitism of fresh H. halys eggs. Differences in developmental success may be related to less efficient venom of European scelionids injected during oviposition. To date, A. bifasciatus is the only potential candidate for augmentaive biological control of H. halys in Europe as it was the only European parasitoid capable of consistent, successful development on fresh H. halys eggs.