Non-native Vespula germanica yellowjackets dominate urban-to-rural gradient

Social insects are highly successful invaders of novel habitats and, of these, wasps and yellowjackets are quite successful worldwide. Vespula germanica (German yellowjackets) have become a pernicious cosmopolitan problem—yet the degree of their urban association and domination remains unclear. We investigated the invasion and behavior of V. germanica in Western New York along a rural–urban gradient to understand their conspecific dominance and their foraging behavior around human activities. We placed yellowjacket baits in urban, suburban and rural sites through the summer season to assess V. germanica dominance, and we conducted behavior trials at picnic tables to observe their responses to human activity. Given that the invasive ecotype prefers to nest in human structures, we predicted that we would find greater V. germanica dominance near structures and in urban areas. Moreover, given that they learn to associate food with cues, we predicted that they would associate human presence/activity at picnic tables with food. We found that V. germanica dominated everywhere (70–95% of all Vespula wasps), but dominance was highest in suburban and urban areas, with a preference for foraging near human structures. Surprisingly, behavior trials revealed that the yellowjackets were less attracted to baits with humans nearby, suggesting an avoidance of human activity rather than learned affinity. These findings reinforce V. germanica’s attraction to human structures and urban environments, and their high negative impact on native yellowjacket populations.