Department of Entomology Columbus, Ohio, United States
The samurai wasp, Trissolcus japonicus (Ashmead) (Hymenoptera, Scelionidae), is a parasitoid that was first detected in Ohio from a sentinel egg sample of brown marmorated stink bug in Franklin County, August 2017. Additional detections in May 2018 were used to start a lab colony. Sentinel egg masses that were deployed at 10 fruit farms in central Ohio in June 2018 did not detect any samurai wasp, thus releases of the wasp were made at five farms, with the other five farms used as a no-release comparison. In August 2018, all 10 farms were sampled with sentinel eggs and with yellow sticky traps, and the samurai wasp was found at one release site and one no-release site. In 2019, an additional 10 fruit farms were sampled with sentinel eggs, no samurai wasps were detected, and releases were made at five of these farms with the other five farms as no-release comparisons. In August 2019 and again in July 2020, all 20 farms were sampled with sentinel eggs. Yellow sticky traps were also used for sampling in 2020. No samurai wasps were detected by either sampling method, thus we have no evidence of the parasitoid being established at the release sites, however the sentinel egg sample size was likely too small or too infrequent for adequate detection. More intensive sentinel egg mass sampling at the original site shows seasonal trends in samurai wasp detection, and the benefit of more frequent sampling.
