Track Them Down: The spatial ecology and behaviour of the enigmatic moss carder bee (Bombus muscorum (Linnaeus, 1758)) and the invasive sculptured resin bee (Megachile sculpturalis Smith, 1853)

Wild bees provide pollination services, which is a key ecosystem function for maintaining local biodiversity and ecosystem resilience. The conservation of rare pollinator species is crucial, because biological diversity and efficient pollination provision depends on a resilient pollinator community. Further, non-native bees might apply positive services to their new environment, but may also negatively affect the native fauna and flora, e.g., by acting as competitors for native bees for nesting sites and floral resources, modify native pollination networks or act as vectors for introduced parasites. A prerequisite of establishing suitable animal conservation measures is to understand the specific habitat requirements and spatial ecology of endangered but as well as invasive species. Recent developments in animal tracking technology expand the use of active radio transmitters even to insects such as larger bees. In our project we apply this approach to vulnerable species (i.e., our first study organism – Bombus muscorum), but also introduced species threatening local bee populations, (i.e., our second study organism – Megachile sculpturalis). We aim to study movement patterns, home range, daily activity patterns of the two species, define ecological niche to predict presence and absence and gain insights in these species’ population density and dynamics over an entire season. In 2022, during the main activity period of the two study species (June-August), we plan to track males (drones) and females (workers in case of bumble bees) using rechargeable active transmitters (Plecotus-Solutions GmbH) specifically designed for large bees (weighing 180 mg). Adverse effects of trackers are infrequently reported in literature and are often based on observations. To quantify possible effects, we will perform preliminary trials for both target species, to compare bee behaviour with and without trackers in a cage experiment. During the duration of the active tracking experiment of individuals in the field (30 days per species), we will install stationary receivers with internal data loggers to store tracking data remotely. To increase signal range (600m-1km), receiver stations will be placed at elevated locations (e.g., roofs in urban habitats, and small hills, open terrain in natural habitats). In addition to the tracking subsequent analysis, a capture re-capture study is planned. This data, along with the tracking data will be used in a spatially explicit open population analysis, which allows estimation of population densities and dynamics, emigration, immigration and survival during the study period. Our results will contribute to establish suitable conservation/control measures for the two study species.