Transmission of bumble bee pathogens


Bee colonies are pretty dense and there  are lots of interactions between individuals, giving parasites a chance to spread within the colony. I tested how fast some pathogens spread within bumble bee and honey bee colonies, and how the initial number of infected bees in the colony affects the spread of the parasites. I used the parasites Crithidia bombi for bumble bees and Nosema ceranae for honey bees, and found that for both parasites, when the initial number of infected bees is small, the social immunity of the colonies is able to control the spread of the parasites. But when the initial number of infected bees is about 30%, the parasites will spread really quickly in the colony.  This means that if we can control the exposure to parasites in the environment, we can also reduce within-colony transmission of parasites.

 Check out a video about that experiment and the paper with the final results 


The way many bee parasites transmit in the environment is by the shared used of flowers. Intestinal parasites, like C. bombi, are released in the feces, and if the feces fall on a flower, another bee can become infected. Given the wide variety of flower shapes and sizes, I wanted to know how the morphology of the flowers affect different steps of the transmission process, including the probability of catching bee feces, survival of the parasite on the flowers, and the actual transmission to new bees.  Check out this video with the preliminary results.