Sampling methods for adventive Trissolcus japonicus (Hymenoptera: Scelionidae) in a wild tree host of Halyomorpha halys (Hemiptera: Pentatomidae)

Authors: QUINN, NICOLE - Virginia Tech; TALAMAS, ELIJAH - Virginia Tech; Leskey, Tracy; BERGH, CHRISTOPHER - Virginia Tech

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/31/2019
Publication Date: 4/30/2019
Citation: Quinn, N., Talamas, E., Leskey, T.C., Bergh, C. 2019. Sampling methods for adventive Trissolcus japonicus (Hymenoptera: Scelionidae) in a wild tree host of Halyomorpha halys (Hemiptera: Pentatomidae). Journal of Economic Entomology. https://doi.org/10.1093/jee/toz107.
DOI: https://doi.org/10.1093/jee/toz107

Interpretive Summary: Eggs of the brown marmorated stink bug (BMSB), an invasive stink bug distributed throughout the USA, has recently been attacked by an egg parasitoid native to Asia and commonly referred to as the Samurai wasp. This wasp was originally found in Maryland in 2014 but has spread to a number of other states. To better monitor for the presence of the Samurai wasp, we compared sentinel egg masses and yellow sticky cards deployed in the lower, middle, and upper canopies of tree of heaven, a common host of BMSB. While both methods resulted in Samurai wasp detections, yellow sticky traps were easier to use. In general, most detections were in the middle and upper canopy. These results provide a simple-to-use method for tracking the spread of the Samurai wasp across the USA.

Technical Abstract: Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive pest that has established in much of the USA. Adventive populations of an effective Asian egg parasitoid of H. halys, Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae), were recently detected in several states including Virginia in 2015, and its geographic range appears to be expanding. Thus, documenting changes in its distribution and abundance have become key research priorities. For these specific purposes, Tr. japonicus surveillance over large geographic areas using sentinel H. halys egg masses may not be optimally efficient, and examination of alternative sampling tactics is warranted. In 2016, sentinel H. halys egg masses were deployed as vertical transects in the canopy of female Ailanthus altissima in Virginia. A brief, preliminary, follow-up study using yellow sticky traps deployed in the same trees yielded Tr. japonicus captures, leading to a comparison of vertical transects of sentinel eggs and yellow sticky traps in 2017. Both methods yielded Tr. japonicus detections only in the mid- and upper tree canopy. Whereas, other known H. halys parasitoids were detected in the lower, middle, or upper canopy. Based on this information, a method for deploying yellow sticky traps in the mid-canopy of H. halys host trees was assessed in 2017, yielding Tr. japonicus captures. A comparison of estimated time inputs required revealed that traps were more efficient than sentinel eggs in this regard. Results are discussed in relation to the utility of each sampling method for addressing specific questions about the range expansion and ecology of Tr. japonicus.