Drought and soil microbial community: Implications for pollinators' preferences and colony fitness

Red Clover (Trifolium pratense) is a perennial legume grown for seed production in Western Canada and is a highly important commodity for the Canadian Prairies. Due to its near self-sterile nature, seed production heavily depends on insect-mediated pollination to ensure seed set and, in turn, high yield. Further, red clover forms mutualistic associations with soil microbes, which are known to enhance seed production and stress tolerance.

Agricultural intensification has decreased biodiversity in plants, animals, and soil microbes. Certain changes in agricultural practices, such as tillage operations or pesticide applications, can also affect the structure, composition, and microbial community of agricultural soils, leading to hydrological changes. These changes directly impact the plants and have cascading effects on native pollinators that provide pollination services due to floral reward quantity and quality alterations.

This study utilized two-choice and no-choice bioassays to investigate the effects of drought and soil microbial community changes on bumblebee foraging behaviour and hive community. A full factorial design was used to test the effects and interactions on Common eastern bumblebee (Bombus impatiens) preference and colony fitness exposed to red clover plants subjected to two treatments: soil treatment (sterilized soil versus field-collected soil) and water treatment (drought versus wet).