Native flora receive more visits than exotics from bees, especially native bees, in an urbanised biodiversity hotspot

Abstract

Context Identifying floral resources preferred by bee assemblages is important for their conservation. Aims Here, I assess the association of flowering plant community composition, with that of honey bees and native bee abundance and diversity. I investigate flower preferences in terms of plant origin (native or exotic), and evaluate niche breadth, of introduced honey bees and native bee taxa. I also consider if habitat influences these patterns. Methods This was evaluated through recording flower visitation by honey bees and native bees in the urbanised region of the south-west Western Australian Floristic Region in seven bushland remnants and seven residential gardens over 2 years. Key results Both native bees and honey bees visited more native than exotic flora, however native bees visited a higher proportion of native flora than honey bees. The 10-most visited plants by native bees were exclusively native, whereas for honey bees, although their 10-most visited plants were predominantly native plant species, this selection also included exotic plant species. Niche breadth was broader in bushland remnants, indicating a greater range of preferred flora in bushland remnants. Honey bees however visited more plant families in residential gardens. With increased honey bee abundance, this was associated with native bees expanding their niche breadth, which may be a response to reduce competition. Flower preference patterns and niche breadth often differed between habitats, indicating that foraging patterns may be mediated by habitat context. Conclusion Native flora are preferred by bees, and native bees have relatively restricted flower preferences, especially compared with honey bees. Implications High proportions of preferred native flora are needed to support diverse native bee assemblages in urban areas.