Abundance, Distribution, and Availability of Trissolcus basalis (Wollaston) (Hymenoptera: Scelionidae) Hosts in a Soybean Agricultural System in Southeastern Queensland

Seasonal patterns of abundance and distribution of all life stages of known Trissolcus basalis (Wollaston) host species on different plant species in a soybean agricultural system in southeastern Queensland, Australia are reported. In particular, the seasonal phenology of different bug species is described with emphasis on periods of oviposition. Twelve hosts for T. basalis were identified, with three pentatomid bugs, green vegetable bug, green stink bug, and horehound bug, predominating. These three species appear to undergo at least three generations per year with mating and oviposition occurring during all months between September and April but mainly during October and January–April. Horehound bug is the only known T. basalis host that does not diapause during winter and continues to oviposit during winter at low levels. These results suggest that T. basalis is not host limited temporally except during winter when hosts are scarce. Results also show that T. basalis hosts are spatially aggregated at a number of levels, but how this affects T. basalis and the subsequent degree of biological control has yet to be investigated.