Natural enemy impact on eggs of the invasive brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), in organic agroecosystems: A regional assessment

• Broad-scale assessment of natural enemies' effect on invasive H. halys eggs in eastern US crops.
• Predation, mainly by chewing predators, accounted for the majority of control of H. halys eggs.
• Parasitism of H. halys eggs by native parasitoids was very low.
• Baseline data to evaluate potential future biocontrol programs and native parasitoid adaptation.

Understanding native natural enemy impacts on the invasive brown marmorated stink bug, Halyomorpha halys (Stål), offers insight into the population dynamics of this invasive pest and the potential for biological control. This two-year study offers a broad-scale assessment of mortality factors affecting sentinel and naturally laid H. halys eggs in agroecosystems in the pest’s invaded range in eastern North America. Predation and parasitism rates varied among states and crops, but overall were low. Average maximum levels of biological control were estimated to be about 19% and 20% in 2013 and 2014, respectively. Of the eggs destroyed by natural enemies, chewing predation was the most prevalent. Parasitism by native parasitoids was very low, with adult parasitoids emerging from <1% of eggs averaged across crops, locations, and years; an additional 2.8% of eggs contained partially developed parasitoids. Lower percentages of sentinel H. halys hatched in organically versus conventionally managed crops, and in most cases had higher percentages of predation. Parasitism of sentinel and naturally laid eggs of the native stink bugs Euschistus servus (Say) and Chinavia hilare (Say) averaged 49.3% (±8.6 SE) and 0.6% (±0.3), respectively, across locations and years. Telenomus podisi (Ashmead) was the most common parasitoid parasitizing E. servus and H. halys eggs, but rarely did >1 individual parasitoid emerge from a H. halys egg mass. Parasitism of H. halys eggs by a complex of parasitoids is an important population regulation factor in its native Asian range, but this study found that parasitoids native to eastern US agroecosystems do not provide that service in this introduced region. The greatest potential for biological control of H. halys may be via classical biological control by the Asian parasitoid Trissolcus japonicus (Ashmead), which has recently been detected in both the eastern and western US.

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