Abundance and Richness of Wild Bees on Organically Managed Lavender Farms

Wild bees are important pollinators in agricultural systems, yet patterns of wild bee abundance and diversity in commercial lavender (Lavandula angustifolia) fields remain poorly characterized. We conducted a preliminary, observational assessment of wild bee abundance and species richness across organically managed lavender fields, including both certified organic and non-certified fields following organic practices, in Provence, France, between 2022 and 2024. Standardized 15-min collections were used to compare wild bee and managed honey bee activity during 66 sampling events, while additional non-standardized collections were used to characterize and qualitatively compare the taxa present in the different field settings. Wild bees represented only 2.8% of bees captured during timed collections and their abundance varied substantially among fields. Because only seven fields were studied and many field characteristics covaried, comparisons involving field size, lavender type, cover crops, tillage, landscape setting, apiary proximity, and management appearance are treated as exploratory patterns rather than independent management effects. At the scale of individual sampling events, wild bee abundance was negatively associated with honey bee abundance and positively associated with temperature, whereas floral abundance along sampling transects was not a strong predictor. Species richness also varied among fields: observed richness ranged from 17 to 88 species among the six sites included in the richness analysis, while Chao1-estimated richness ranged from 30.2 to 132.6 species. These results document substantial variation in both abundance and richness among lavender fields and identify patterns that warrant testing with larger, independently replicated studies.