Host kairomones influence searching behavior of Trissolcus japonicus (Hymenoptera: Scelionidae), a parasitoid of Halyomorpha halys (Heteroptera: Pentatomidae)

Authors: BOYLE, SEAN - University Of Delaware; Weber, Donald; HOUGH-GOLDSTEIN, JUDITH - University Of Delaware; Hoelmer, Kim

Submitted to: Environmental Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/5/2019
Publication Date: 12/16/2019
Citation: Boyle, S.M., Weber, D.C., Hough-Goldstein, J., Hoelmer, K.A. 2019. Host kairomones influence searching behavior of Trissolcus japonicus (Hymenoptera: Scelionidae), a parasitoid of Halyomorpha halys (Heteroptera: Pentatomidae). Environmental Entomology. 49(1):15-20. https://doi.org/10.1093/ee/nvz155.
DOI: https://doi.org/10.1093/ee/nvz155

Interpretive Summary: The brown marmorated stink bug has become a serious invasive agricultural and nuisance pest across North America and Europe. Our laboratory host range evaluations determined the egg parasitoid Trissolcus japonicus (“samurai wasp”) to be the primary candidate biocontrol agent for the stink bug. However, initial laboratory evaluations only show us the potential host range of natural enemies and do not account for behavioral choices made by natural enemies in response to different environmental cues. Previous studies with other egg parasitoids have shown that detecting chemical cues left by their pest hosts can significantly influence the searching behavior of the parasitoids. To assess the samurai wasp’s host selection process, wasps were exposed to leaf surfaces contaminated by the brown marmorated stink bug or from the spined soldier bug, a potential alternate host species that is a useful native predator of various pest insects in agricultural and forest ecosystems. We found that the samurai wasp displayed significant foraging preferences for leaves contaminated with chemical traces of brown marmorated stink bug. Our study suggests that behavioral studies may be used to further evaluate the host specificity of samurai wasp and can be an invaluable supplement to classical biocontrol host range testing regimes.

Technical Abstract: The brown marmorated stink bug, Halyomorpha halys, is a highly polyphagous species native to Asia that has become a serious invasive agricultural and nuisance pest across North America and Europe. Over the last decade, classical biological control host range evaluations have revealed the solitary egg parasitoid Trissolcus japonicus to be the primary candidate biocontrol agent for field release against H. halys. However, these evaluations only provide us with the physiological host range of T. japonicus. Previous studies with other Trissolcus species have demonstrated that contact kairomones from different host species elicit varied responses in the parasitoids’ host foraging behaviors. To assess the parasitoid’s ecological host range, mated naïve T. japonicus females were exposed to leaf surfaces contaminated with contact kairomones from its preferred host, H. halys, or from a native non-target host, Podisus maculiventris. Red maple, apple, and soybean were used as plant substrate treatments. The wasp’s residence time on the leaf surface, linear walking speed, and angular velocity were observed and measured using Noldus EthoVision XT tracking software. T. japonicus displayed significant host foraging preferences for leaves contaminated with contact kairomones from H. halys. The parasitoid resided on H. halys contaminated leaves for approximately twice as a long as it did on P. maculiventris contaminated leaves. Also, T. japonicus walked more slowly on H. halys contaminated red maple leaves than on P. maculiventris contaminated red maple leaves. Overall, our study suggests that kairomone-based behavioral studies can be used to further evaluate the host specificity of T. japonicus and can be an invaluable supplement to classical biocontrol host range testing regimes.