Sunflower plantings reduce a common gut pathogen and increase queen production in bumble bee colonies
Rosemary L. Malfi, Quinn S. McFrederick, Giselle Lozano, Rebecca E. Irwin, and Lynn S. Adler
We evaluated whether plantings of sunflower (Helianthus annuus), whose pollen reduces infection by some pathogens when fed to bees in captivity, lowered pathogen levels and increased reproduction in free-foraging bumble bee colonies (Bombus impatiens). We placed pairs of commercial colonies of B. impatiens at 20 mixed vegetable farms in western Massachusetts between Jul-23 and Oct-6 2019. Flowering resources typically visited by bumble bees were quantified at each farm twice to characterize abundance and diversity. We also visited each farm 3-4 times and at each visit, we (a) recorded colony weights to track growth, (b) collected ~10 corbicular loads from returning foragers (per site) to assess usage of sunflower and other Asteraceae, and (c) collected 10 returning foraging workers from each colony entrance for later pathogen analysis. Visual assessment of pathogen samples and pollen composition occurred at UMass Amherst during the 2019-20 academic year. Molecular assessment of pathogen samples occurred at UC Riverside. An associated manuscript with this title and these authors is being submitted for publication.
The Intersection of Bee and Flower Sexes: Pollen Presence Shapes Sex-Specific Bee Foraging Associations in Sunflower
Justin C. Roch, Rosemary Malfi, Jennifer I. Van Wyk, Deicy Carolina Muñoz Agudelo, Joan Milam, and Lynn S. Adler
We evaluated whether female or male bees were more abundant on sunflowers, whether female bees were more abundant on pollen-fertile or pollen-sterile sunflower cultivars, and whether the bee community differed between pollen-fertile and pollen-sterile sunflower cultivars. We further evaluated whether bee communities were shaped by local floral resources and landscape composition. We sampled bees visiting sunflowers (Helianthus spp.) from 14 farms in the Connecticut River Valley of western Massachusetts between 25 July to 27 September 2019, typically making two sampling visits to a farm. We also measured floral resource diversity and abundance at the farms, and categorized the landscape types at 500 m, 1000 m, 1500 m, and 2500 m radii around the farms using GIS data. All sampled bees were identified to species or species complex. An associated manuscript with this title and these authors is being submitted for publication.