Nesting habitat and prey preferences in two caterpillar-hunting Anterhynchium species (Hymenoptera: Vespidae: Eumeninae)

Many wasps hunt prey and transport them to nests located far from prey-hunting sites. While many studies have presented either prey preferences or nesting habitat selection in hunting wasps, few have investigated whether prey habitats are closely linked to nesting habitats. To clarify the relationship between prey and nesting habitats, we studied the prey items and nesting habitats of the two caterpillar-hunting wasps, Anterhynchium flavomarginatum and Anterhynchium gibbifrons (Hymenoptera: Vespidae: Eumeninae), in a mixed agricultural and forest landscape in Hyogo, central Japan. Trap nests were placed in four environments, agricultural fields, bamboo forest edges, broad-leaved forests, and bamboo/broad-leaved forest boundaries, from June to November 2020. Anterhynchium flavomarginatum and A. gibbifrons nested in 25% and 60% of the 48 trap nests, respectively. The former nested in all four environments, whereas the latter nested at bamboo forest edges, in broad-leaved forests, and at the boundaries. Anterhynchium flavomarginatum provisioned its nests with larvae of 15 moth species (Lepidoptera: Crambidae, Pyralidae, Tortricidae), whose host plants were found in agricultural fields and other environments. In contrast, A. gibbifrons provisioned its nests exclusively with larvae of Demobotys pervulgalis (Crambidae), with its host plants restricted to bamboo. Our findings suggest that prey availability influences nesting habitat selection in the two Anterhynchium species. Anterhynchium flavomarginatum showed greater habitat flexibility, likely due to its broader prey range, whereas A. gibbifrons exhibited a narrow habitat range corresponding to the host plant distribution of its sole prey species.