Effect of temperature on the biology of Trissolcus japonicus and Trissolcus mistukurii, two egg-parasitoids of Halyomorpha halys

Halyomorpha halys (Stål) (Hemiptera: Pentatomidae) is an invasive agricultural pest native to Asia and spread out in many countries in America and Europe. Its widespread expansions resulted in significant financial losses to several fruit-growing regions in northern Italy. Classical biological control has been the most promising long-term pest management strategy for reducing H. halys populations. Recently, adventive populations of Asian egg parasitoids Trissolcus japonicus and Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae) have been discovered in Italy. In a laboratory experiment, the life table parameters of these two egg parasitoid species were investigated under three constant temperatures (21, 26 and 31°C). The survivorship of T. japonicus resulted higher as compared to T. mitsukurii at all temperatures considered. Moreover, T. japonicus parasitism performances were higher than T. mitsukurii at 26°C and 31°C. However, the T. mitsukurii population can grow faster than T. japonicus at 21°C. These outcomes suggest better performances of T. mitsukurii in the first part of the growing season, while T. japonicus should perform better during the summer.