Abstract
The invasive stink bug Halyomorpha halys is a severe agricultural pest of worldwide importance, and chemical insecticides are largely sprayed for the control of its populations. Negative impacts and several failures in chemical pest management led to consider classical biological control as one of the most promising methods in a long-term perspective. The Asian egg parasitoid Trissolcus japonicus is the main candidate biocontrol agent of H. halys, but more recently a second Asian egg parasitoid, Trissolcus mitsukurii, is getting attention after adventive populations were found on H. halys egg masses in Europe. Before recommending the use of T. mitsukurii for biological control of H. halys, a risk analysis is necessary and therefore here we present the first study on the fundamental physiological host range of this parasitoid in Europe. Tests conducted with T. mitsukurii on different hemipterans, using three different experimental designs, revealed a broad physiological host range, comparable with the host range displayed by T. japonicus under similar laboratory conditions. Specifically, in addition to its coevolved host H. halys, T. mitsukurii successfully parasitized the majority of tested pentatomid species and one scutellerid, although with highly variable emergence rates. Host egg sizes positively affected parasitoid size and female egg load. Further studies, testing more complex systems that involve olfactory cues from host and host plants, will simulate different aspects of the parasitoid host location behavior under field conditions, allowing in-depth evaluation of the possible risks associated with the use of T. mitsukurii as a biocontrol agent of H. halys.
