?Early-phase colonisation by introduced sculptured resin bee (Hymenoptera, Megachilidae, Megachile sculpturalis) revealed by local floral resource variability

There is a growing interest to document and better understand patterns processes involved in non-native bee introductions subsequent colonisation of new areas worldwide. We studied the spread East Asian Megachile sculpturalis Serbia south-eastern Europe; was earlier established USA (since 1994) western Europe 2008). Its establishment remained dubious throughout most 2017–2019, following its first detection. hereby report on spreading, which were corroborated 2019 under specific circumstances. Owing an exceptionally poor blooming Styphnolobium japonicum 2019, we recorded high activity density M. concentrated scarce key food resource. present novel quantitative approach for improved early detection , based interplay between local occurrence pattern dynamics food-plant(s) availability. This seems particularly effective during early-phase colonisation, at initially low population introduced bees. address importance integration genuine plant usage with context-specific assessment options establishing monitoring. The understanding triggered questions about possible origin(s) modes dispersal east Alps. To explore scenarios introduction(s), extended study wider spatio-temporal context – region SE (2015–2019). two complementary approaches (at regional scale) provided more comprehensive evidence history varied recording contexts. Based this two-scale approach, suggest that diffusive mode introduction into now be plausible scenario (than long-distance jump). argue outcomes from contrasting (a systematic surveillance, resources broad-scale opportunistic recording) could great methodological relevance development future monitoring protocols.