This summer I had the opportunity to work in the Adler lab with an incoming PhD student, Sonja Glasser, on a research project investigating the effects of planting sunflower family (Asteraceae) flowers on farms to combat a common bee pathogen, Crithidia bombi. Crithidia infects up to 80% of bumble bees in Massachusetts and can reduce colony-founding ability, colony size, and male production. Past research in the Adler lab has shown that planting sunflowers on farms dramatically reduces Crithidia infection in bumble bees, so we wanted to see if other plants in the Asteraceae family also have this medicinal effect. We hypothesized that bumble bees on farms with more Asteraceae cut flowers would have lower pathogen loads compared to bees on control farms with few Asteraceae cut flowers. If our hypothesis was supported, farmers could plant these flowers to improve bee health while growing a specialty crop.
Throughout the summer, our team collected bumble bees and quantified floral resources from 3 “cut flowers” farms with at least ½ acre of Asteraceae flowers and from 3 “control” farms with less than 1/10 acre of Asteraceae flowers. The collected bees were dissected to count the number of Crithidia cells in a gut sample. After analysis, we did not find that farms with high acreage of Asteraceae flowers significantly reduced infection compared to control farms. Some hypotheses for why we found this result are that Asteraceae pollen does not reduce Crithidia or that the bumble bees were not collecting enough pollen to reduce infection. Overall, the data does not support planting Asteraceae on farms to reduce Crithidia infection. For further research, the Adler lab will test whether Asteraceae pollen can reduce infection in a laboratory using commercial bumble bees.