Native to Asia, the samurai wasp has emerged as a promising weapon in the fight against the diabolical plant bug, a notorious pest that wreaks havoc on crops. Recently identified in France's Nouvelle-Aquitaine region, this parasitoid wasp could provide a natural, effective solution through its unique ability to parasitize the bug's eggs. While this discovery offers hope for sustainable agriculture, it also raises important questions regarding its ecological impact and practical implementation. 
© INRAE, Alexandre Bout
Trissolcus japonicus, commonly known as the samurai wasp, is a parasitoid species that naturally regulates populations of the diabolical bug (Halyomorpha halys) in its native regions of Asia, including China, Japan, Korea, and Taiwan. First detected in the United States in 2014 during studies seeking natural enemies of H. halys, the wasp was also found in Europe in 2017, specifically in Switzerland and Italy, during similar research initiatives. This pest targets various crops, from soybeans and maize to fruits and ornamental trees.
The samurai wasp combats the diabolical bug by laying its eggs inside the pest's eggs. As the wasp larvae develop, they destroy the bug eggs, with one adult wasp emerging from each parasitized egg.
In Nouvelle-Aquitaine, research conducted under the "RIPPOSTE" project, led by INRAE, ANPN (Association Nationale des Producteurs de Noisettes), and the University of Turin, has yielded significant findings. Between 2022 and 2023, scientists collected 56 specimens of T. japonicus from nearly 3,700 H. halys eggs. Morphological and molecular analyses confirmed the presence of the samurai wasp, likely introduced via pathways similar to those of Trissolcus mitsukurii, another parasitoid of H. halys identified in 2020.
This discovery is seen as a significant step toward controlling diabolical bug populations. Project partners are now focused on releasing and acclimatizing T. japonicus across France, with regulatory approvals already in place. Long-term monitoring will assess the establishment and dispersal of T. japonicus and T. mitsukurii. However, challenges remain: Will these wasps survive French winters? Can they consistently locate suitable hosts? Additionally, potential competition between the two parasitoid species warrants further study.
Published in the Journal of Hymenoptera Research in November 2024, this research offers a foundation for innovative biological control strategies. By mitigating the damage caused by H. halys, these approaches aim to protect crops while preserving ecological balance.
Reference: Martel G, Bout A, Tortorici F, Hamidi R, Tavella L, Thomas M (2024). "First detection of Trissolcus japonicus (Ashmead) (Hymenoptera, Scelionidae) in southwestern France." Journal of Hymenoptera Research 97: 1123–1139.
https://doi.org/10.3897/jhr.97.132433
Source: inrae.fr