First discovery of adventive populations of Trissolcus japonicus (Ashmead) in Europe

Authors: STAHL, JUDITH - Commonwealth Agricultural Bureau International (CABI) - Switzerland; TORTORICI, FRANCESCO - University Of Torino; PONTINI, MARIANNA - University Of Torino; BON, MARIE-CLAUDE - European Biological Control Laboratory (EBCL); Hoelmer, Kim; MARAZZI, CRISTINA - Cantonal Phytosanitary Service; TAVELLA, LUCIANA - University Of Torino; HAYE, TIM - Commonwealth Agricultural Bureau International (CABI) - Switzerland

Submitted to: Journal of Pest Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/27/2018
Publication Date: 10/31/2019
Citation: Stahl, J., Tortorici, F., Pontini, M., Bon, M., Hoelmer, K.A., Marazzi, C., Tavella, L., Haye, T. 2019. First discovery of adventive populations of Trissolcus japonicus (Ashmead) in Europe. Journal of Pest Science. 92:371-379. https://doi.org/10.1007/s10340-018-1061-2.
DOI: https://doi.org/10.1007/s10340-018-1061-2

Interpretive Summary: The brown marmorated stink bug (BMSB), Halyomorpha halys, is an invasive stink bug that attacks a wide variety of tree fruits, vegetables, and field crops. Originating from Asia, the pest has spread during the last decade throughout North America and more recently Europe. As a response to this invasion, classical biological control programs were launched in several countries invaded by the pest, to search for natural enemies to control the pest, especially parasitoids attacking the eggs. As part of this program, field surveys were conducted in Switzerland using frozen sentinel eggs of the stink bug to determine what species of natural enemies may already be present. One of the parasitoids recovered from apple orchards in the Canton Ticino, Switzerland in 2017 and 2018 looked like the Asian species Trissolcus japonicus. We conducted detailed morphological studies and molecular genetic analysis which confirmed this identification. This is the first report of this species in Europe, and the second in invaded countries, the first being in the U.S. The parasitoid was presumably accidentally introduced, possibly along with its host. This parasitoid is considered as a biological control agent, so it may be helping to reduce the pest population. Surveys will be continued to evaluate the establishment and spread of this parasitoid as well as the presence of other parasitoid species.

Technical Abstract: The brown marmorated stink bug, Halyomorpha halys, native to East Asia, has emerged as an invasive pest in Europe in the 2000s. In its native range, Trissolcus japonicus is the dominant egg parasitoid of this pest, and thus, it has been considered for classical biological control in countries invaded by the pest. A survey of native egg parasitoids conducted in 2017 and 2018 with frozen, sentinel egg masses of H. halys revealed that T. japonicus was already present in apple orchards in the Canton Ticino, Switzerland. This parasitoid was recovered in both years and from two different sites. A phylogeographic analysis using the barcode mitochondrial DNA evidenced a best match of the “Ticino” populations to Japanese populations so far, possibly indicating an introduction from Japan, but the pathways of entry remain unknown.