Influence of pollen quantity and nutritional quality on wild bee foraging choices in agricultural landscapes
(2025)
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- Authors
- Supervisors
- Jacquemart, Anne-Laure
- Abstract
- This thesis investigates the influence of the nutritional quality and availability of floral resources on the foraging behavior of wild bees in the agricultural landscapes of Wallonia. Field surveys, pollen chemical analyses, and ecological modeling were combined to explore the relationships between farming practices, pollen nutrition, and plant–pollinator interactions. The study provides an integrated view of pollen availability according to biotopes, management intensity, phenology, and inter-annual variation. The resilience of pollen resources relied on the complementarity of biotopes: (1) croplands provided massive but short-lived inputs, (2) semi- or extensively managed grasslands ensured greater continuity and diversity, and (3) woody elements supplied early and summer floral resources. Agricultural intensification was accompanied by a simplification of bee–plant interaction networks and a decline in diversity, whereas semi-intensive landscapes retained a network organization comparable to that of extensive systems, highlighting their key role in maintaining ecological functions within agroecosystems. Bumblebee pollen-collection choices were influenced by landscape-scale floral diversity and species traits (flower morphology and nutritional quality of floral resources). They prioritized pollens with balanced protein–lipid ratios and flowers producing sugar-rich nectar. The nutritional balance of pollen, rather than total macronutrient content, was the main driver of foraging decisions. A functional approach to pollen, integrating nutritional, ecological, and phenological dimensions, was developed. The results provide practical recommendations to promote a heterogeneous and temporally staggered mosaic of habitats — including delayed mowing, hedgerow preservation, fallows, and the maintenance of key species — to balance the quantity, accessibility, and nutritional quality of floral resources throughout the season.
- Affiliations
Citations
Jeannerod, L. (2025). Influence of pollen quantity and nutritional quality on wild bee foraging choices in agricultural landscapes. https://hdl.handle.net/2078.5/270844