Comparative life tables of Trissolcus japonicus and Trissolcus mitsukurii, egg parasitoids of Halyomorpha halys

Abstract

Trissolcus japonicus (Ashmead) (Hymenoptera: Scelionidae) and Trissolcus mitsukurii (Ashmead) (Hymenoptera: Scelionidae) are Asian egg parasitoids that are considered important natural enemies of the brown marmorated stink bug Halyomorpha halys (Stål) (Hemiptera: Pentatomidae). These species are expanding their geographic distribution outside their native area, which suggests investigating their adaptability to environmental conditions. In a laboratory experiment, we investigated the life table parameters of these two egg parasitoid species under four constant temperatures, i.e., 16, 21, 26 and 31 °C. Results showed that the longevity of T. japonicus was higher than that of T. mitsukurii at all temperatures considered. The net reproductive rate ($\mathrm{Ro}$) of T. japonicus was higher than that of T. mitsukurii at 26 and 31 °C. However, the intrinsic rate of increase ($r_m$) at 26 and 31 °C was similar between the two species, and at 21 °C, T. mitsukurii exhibited a higher intrinsic and finite rate of increase. The two species complete their development at 16 °C, but with the lowest performances. Results suggest a higher increase of T. mitsukurii population when mean temperatures are equal to 21 °C, while the population increase of T. japonicus is expected to be favoured at higher temperatures.