Bumblebees are furry and critical pollinators that are sadly vulnerable to many things such as heat and predators. Another thing that affects their populations that we can keep an eye out for in our gardens is parasites. 

Recent research from North Carolina State University showed that the shapes of certain flowers reduced the number of parasites that affect bumblebee populations. 

Picking the right flowers

The team was looking at the common eastern bumblebee (Bombus impatiens) and a gut parasite called Crithidia bombi. They wanted to see if flower traits like size, shape, and number affected the rate of transmission of parasites to bumblebees. Parasites have been a major contributor to the bumblebee population decline. 

In particular, they were looking at the three main steps that led to transmission to bees on flowers. These were fecal deposition on flowers, parasite survival on flowers, and acquisition of the parasite by a new bee host.

“Of the flower traits we measured, the floral shape was the best predictor of parasite transmission to bees,” said Mario Simon Pinilla-Gallego, a former Ph.D. student in the department of applied ecology at North Carolina State University and co-corresponding author of a paper

“Wide and short flowers—like black-eyed Susans and coneflowers—reduce the survival of the parasite on flowers, but at the same time they collect more bee feces, and bees are more likely to come in contact with and acquire the parasite on these types of flowers,” said Rebecca Irwin, professor of applied ecology and co-corresponding author of the paper. 

The team believes that identifying flowers with high rates of parasite transmission could be a net bonus for pollinators. Improving floral and pollination resources for bees could even be put in the hands of everyday gardeners, looking to help their local environment. 

Source Study: Ecology — Floral shape predicts bee–parasite transmission potential – Pinilla‐Gallego – – Ecology – Wiley Online Library