Bumblebee Foraging Preferences : a Case Study at Frantsila Herbal Farm

Abstract

This thesis examines bumblebees’ foraging preferences at Frantsila Herbal Farm in Hämeenkyrö, Finland. This case study was conducted in an organic agricultural setting by investigating the relationship between herbal flowering plant abundance and bumblebees’ foraging behaviour with the aim of revealing ecological balance. The thesis objectives were identifying the flowering plant that attracts the most bumblebees, the type of bumblebees that can be seen in the farm, and how the foraging choices change in the flowering season. The case study was designed by examining eight herbal flowering plants by counting bumblebees using a line counting method. The background highlights the vital role of bumblebees as pollinators and bioindicators of ecosystem health. Bumblebees are sensitive to biotic and abiotic stress caused by anthropogenic activities. Climate change, the availability of flowering plants, intensive agriculture, and usage of pesticides heavily influence their existence. The presence of bumblebees reveals the ecological balance of farm environments and strengthens the sustainability of agricultural practices. Although bumblebees have been heavily researched in previous studies, most of these studies focus on controlled environments. Fewer studies are available on organic farm settings. Case study outcomes show a notable change in foraging preferences. Salvia officinalis, prunella vulgaris, and trifolium pratense bloomed at the beginning of the flowering season by welcoming the bumblebees. Echinacea purpurea was the most attractive plant in the middle of the flowering season. Nepeta cataria, centaurea cyanus, and calendula officinalis emerged as late-seasonal flowers. Nepeta cataria and centaurea cyanus were able to attract bumblebees together more than Eechinacea purpurea. However, Medicago sativa was recorded as the least attractive plant among Bumblebees. Trifolium pratense stands out as a moderately attractive food source during the flowering season. Bombus lapidarius bumblebees were identified as the dominant bumblebee species. The conclusion of this case study underscores the importance of diverse flowering resources throughout the flowering season and pollinator-friendly agricultural practices of the Frantsila Herbal Farm. Creating undisturbed habitats in north-facing slopes to ensure higher survival during winter, establishing spruce hedgerows towards the neighbouring conventional farms against pesticides and wind, and establishing Salix bushes to provide early food sources for bumblebees can be recommended to align with Finland’s National Pollinator Strategy 2030.