Seasonal Abundance and Diversity of Egg Parasitoids of Halyomorpha halys in Kiwifruit Orchards in China

SIMPLE SUMMARY: Surveys of egg parasitoids of the brown marmorated stink bug, Halyomorpha halys, were conducted in 2018 and 2019 in green-fleshed ‘Hayward’ kiwifruit orchards in Mei County, Shaanxi Province, China, to assess the abundance and diversity of parasitoid communities under two different management systems. Parasitism occurred from June to August and from May to August across the two survey seasons, respectively. Five parasitoid species were recovered from successfully parasitized H. halys egg masses, where Trissolcus japonicus and Trissolcus cultratus were the predominant species. The abundance of T. japonicus varied throughout the season in both orchards in both survey seasons. Monthly T. japonicus abundance showed a unimodal distribution in 2018, peaking in July. There were two peaks (May–June and August) in the 2019 season. This study provides valuable information on the season-long abundance and diversity of egg parasitoids of H. halys in kiwifruit, and most importantly on the abundance and effectiveness, relative to other parasitoids, of T. japonicus in kiwifruit orchards. ABSTRACT: To develop effective and targeted biocontrol tactics for the brown marmorated stink bug, Halyomorpha halys, in crop habitats, a good understanding is essential of the abundance and diversity of its parasitoids in different crop habitats in its native range. To obtain information on the egg parasitoid communities of H. halys in kiwifruit, surveys using sentinel egg masses were conducted in 2018 and 2019. These assessed the species composition of egg parasitoids of H. halys in green-fleshed ‘Hayward’ kiwifruit orchards, and quantified their season-long abundances in orchards under two different management systems. Parasitism was observed from June to August 2018 (mean parasitism: 48%) and from May to August 2019 (mean parasitism: 29%) across the experimental orchards. In total, five different parasitoid species were found across the two surveys seasons in the kiwifruit orchards, Trissolcus japonicus, T. cultratus, T. plautiae, Anastatus japonicus, and Acroclisoides sp., where T. japonicus and T. cultratus were the predominant species. Monthly T. japonicus abundance data had a unimodal distribution in 2018, peaking in July. There were two peaks (May–June and August) in the 2019 season. Overall, T. japonicus was significantly more abundant in the organic orchard than the conventionally managed orchard only in 2018, and its monthly abundance differed significantly in the two orchards in the two survey seasons. Results and their implications for future classical biological control for H. halys in kiwifruit are discussed.