Habitat alteration, habitat loss, and introduction of alien species are common signs of human dominated landscapes. Alien plant species that become invasive are an ongoing threat to native biodiversity within intact ecosystems. However, some invasive species have been incorporated into landscapes and associated ecosystem processes for decades, provoking questions concerning adaptation to, and potential reliance on, invasive resources by native communities. Lonicera maackii is an alien invasive shrub with dense floral displays in spring and is patchily distributed throughout much of the eastern United States. Studies corroborate that L. maackii is a driver of ecosystem change with detrimental effects on multiple flora. What remains unclear is the impact of its dense and nectar rich, but ephemeral, floral resources on pollinator communities. To temporally define mechanistic responses of the bee community to the invasion of L. maackii, we sampled bees from April to November (2015) along edges of 12 large forest remnants in southwestern Ohio and southeastern Indiana that collectively represented a density gradient of L. maackii shrubs. We also recorded tree identities and floral counts of neighboring herbaceous species within each 10 m x 100 m plot to understand the effect of the flowering community on bee community composition.
Results/Conclusions
From April 23 to July 2, we sampled 6,194 bees from 27 genera and 4 families. We found that bee community composition responded predictably to L. maackii density during the L. maackii blooming period (May 11 to June 1) (p<0.05) and increased in abundance (ΔAICc = 17.30) and genera richness (ΔAICc = 12.76) regardless of surrounding floral richness or patch size. Interestingly, we saw exceptional increases in Ceratina and Lasioglossum (Dialictus) populations, but strong declines in abundances of wood nesting Augochlora pura with increasing L. maackii density. Following the blooming period of L. maackii from June 2 to July 2 we found continued growth at a lesser magnitude in bee communities. The end of the bloom coincided with strong decreases in Andrena, Eucera, and Peponapis abundances and the appearance of Mellisodes and Anthophora species. These results provide strong evidence that L. maackii is beneficially affecting native bee communities into the summer by providing supplemental food, and possibly nesting, resources in the spring.