Stuligross, C. | bioRxiv Science

bioRxiv2025

Floral microbes provisioned by Osmia lignaria establish in larval food stores, but do not affect bee development or survival

Microbial dispersal and subsequent establishment among linked habitats can be used to examine drivers of community assembly and function. Flowers host microbial communities that can be acquired and vectored by bees to new flowers, establish within the adult bee gut, and enter food stores (e.g., pollen provisions) of developing larvae. Yet, whether microbes vectored by insects or applied for biocontrol can establish across these habitats and if they affect bee fitness remain unknown. Here, we applied microbes to flowers visited by blue orchard bees (Osmia lignaria) and compared microbial communities in flowers, adult bee guts, and pollen provisions before and after inoculation to determine microbial establishment, environmental filtering, and overlap across habitat types. We also inoculated provisions with microbes to test their effects on larval survival and development. Experimentally inoculated microbes were detected in all habitats, demonstrating that flowers are a source of microbial acquisition for adult and larval bees. Additionally, larval health was not impacted by microbe supplementation, indicating tolerance of bee larvae to floral microbes in Osmia.

microbiology↗

bioRxiv2021

A meta-analysis of single visit pollination effectiveness

Many animals provide essential ecosystem services in the form of plant pollination. A rich literature documents considerable variation in the single visit pollination effectiveness of different plant visitors, but this literature has yet to be comprehensively synthesized. We conducted a hierarchical meta-analysis of 193 studies and extracted 1716 single visit effectiveness (SVE) comparisons for 252 plant species. We paired SVE data with visitation frequency data for 75 of these studies. Given the global dominance of honeybees in pollinator communities, we used these data to ask: 1) Do honeybees (Apis mellifera) and other floral visitors vary in their SVE?; 2) To what extent do plant and pollinator attributes predict the difference in SVE between honeybees and other visitors?; and 3) Is there a correlation between floral visitation frequency and SVE? We found that honeybees were significantly less effective than the most effective non-honeybee pollinator. Although not significantly different, honeybees also tended to be less effective than the mean community effectiveness. Honeybees were less effective as pollinators of crop plants and when compared to birds and other bees. Visitation frequency and pollination effectiveness were positively correlated, but this trend was largely driven by data from communities where honeybees were absent, suggesting that honeybees generally combine high visitation frequency and lower SVE. Our study demonstrates that non-honeybee floral visitors are highly effective pollinators of many crop and non-crop plants. While the high visitation frequency typically displayed by honeybees undoubtably makes them important pollinators, we show that honeybees are slightly less effective than the average pollinator and rarely the most effective pollinator of the plants they visit. As such, honeybees may be imperfect substitutes for the loss of wild pollinators and safeguarding global crop production will benefit from conservation of non-honeybee taxa. Open Research StatementAlthough we are fully committed to data transparency, we are also aware of different research teams working on related meta-analyses. As such, we prefer to wait until our paper is accepted to make data publicly available but are happy to share data upon request. Data will be permanently archived on Figshare following acceptance.

ecology↗