Competitive Effects of a Recently Invading Wasp Species on a Native Congener in the Presence of Native Ants

When native and non-native congeners use the same resource, non-natives can competitively exclude natives. To clarify the effects of native ants on competitive interactions between native and non-native congeners, we experimentally investigated interactions between a native wasp species, Anterhynchium flavomarginatum, and a recently invading congener, Anterhynchium gibbifrons (Hymenoptera: Vespidae), using control and ant-excluded trap nests in central Japan. A total of 48 trap nests (12 bamboo canes per trap nest) were placed at forest edges between June and October 2021. Ants, which are native predators and nest-site competitors of Anterhynchium wasps, were experimentally excluded from half of the trap nests using a sticky barrier. Out of 288 control and 288 ant-excluded bamboo canes, A. flavomarginatum nested in 5.6