Effect of temperature on egg parasitoids of Halyomorpha halys
Halyomorpha halys (Hemiptera: Pentatomidae – formerly EPPO Alert List) originates from Asia and has emerged as an invasive pest in North America and Europe in the 1990s and 2000s, respectively. Two scelionid egg parasitoids were considered the most effective natural enemies of H. halys in Asia: Trissolcus japonicus (Hymenoptera: Scelionidae) and Trissolcus mitsukurii (Hymenoptera: Scelionidae). The temperature related development of the two parasitoids, was assessed under four constant temperatures (16, 21, 26 and 31°C). Laboratory colonies of T. japonicus, T. mitsukurii and H. halys were established from field collected insects in Veneto region, North-East Italy. Before the temperature experiment, the parasitoids were reared on H. halys egg masses at 25°C. 10 males and 10 females of T. mitsukurii and the same numbers of T. japonicus were placed in a constant temperature chamber with a fresh H. halys egg mass for 24 hours. Following this, the egg mass was removed and placed into a separate chamber with the same temperature. Parasitoid couples and parasitised egg masses were observed daily to check parasitoid emergence and survival. The longevity of T. japonicus was higher than T. mitsukurii for all temperatures. The reproductive rate of T. japonicus was higher than that of T. mitsukurii at 26 and 31°C. Both parasitoid species completed their development at 16°C, but with low performance. Results showed that T. mitsukurii had a higher population increase when mean temperatures are 21°C, while T. japonicus population increase was favoured by higher temperatures.
Sources
Mele A, Avanigadda DS, Ceccato E, Olawuyi GB, Simoni F, Duso C, Scaccini D, Pozzebon A (2024) Comparative life tables of Trissolcus japonicus and Trissolcus mitsukurii, egg parasitoids of Halyomorpha halys. Biological Control 195 105548.