Home-and-away comparisons of life history traits indicate enemy release and founder effects of the solitary bee, Megachile sculpturalis

Abstract

Occurrences of introduced and invasive pollinators are increasing worldwide. To predict the potential impacts of exotic bees on native ecosystems we need to understand their ecological interactions. Life history traits are fundamental for understanding ecological interactions and often help to explain the spread of exotic species. We conducted home-and-away comparisons of life history traits of the first invasive bee in Europe, the sculptured resin bee Megachile sculpturalis Smith 1853. We compiled information on nest architecture, offspring, natural enemies, body size and phenology using published literature, museum specimen, data from citizen science initiatives, field observations and reared specimen. Megachile sculpturalis uses a broad variety of nesting materials for brood cell construction, including even plastic at the exotic range. Body size at warm temperate climate was similar in the native and exotic ranges, but phenology shifted forward by about one month (28.9 ± 3.3 SE days) in the exotic ranges. The abundance of natural enemies was similar between native and exotic ranges but specialist enemies were missing in the exotic ranges. These trait shifts may be explained by founder effects or ecological filtering. The comparison of life history traits in native and exotic ranges sheds light on the ecological-evolutionary process of this quickly spreading species and provides a better understanding of invasion processes in solitary bees.