Beyond toxicity: the effect of pesticides on pathogen transmission Ginamaría Román Echevarría, M.S. candidate in Entomology

Bees, despite their many amazing behaviors, don’t always know what’s good for them. And flowers, despite their dainty, innocuous appearance, are actually akin to the bathroom doorknob of an insect pollinator’s world: they are covered in microbes. When visiting a flower for nectar, bees inadvertently spread these microbes, depositing their own and picking up others. Some of these, called pathogens, cause disease. What’s more, bees actually prefer to feed from flowers with trace amounts of certain pesticides, especially neonicotinoids. The consequences of this interaction between pathogen and pesticide for bee health are unknown, but potentially dire.

Enter Ginamaría Román Echevarría, a MSc. student in Entomology at Penn State University.

I want to understand the role of pollinator behavior and pesticide exposure on pathogen transmission. We aim to understand how the time a pollinator interacts with a flower and the amount of pollinators that visit a flower impacts the amount of pathogen left behind.

To study this, Román will let bumble bees forage on pumpkin flowers that have either been treated with neonicotinoids or not, and record the number of visits by bumble bee workers, the duration of those visits, and the resulting pathogen load on the flowers. If bumble bees spend more time visiting the neonicotinoid treated flowers, those flowers will likely harbor more pathogens, leading to a higher risk of disease for the bees that visit them.

These results will have implications beyond bumble bees and pumpkins, as many of the pathogens on flowers can be transferred between insect species and impact the whole pollinator community. “The ultimate goal is to put this type of knowledge into the hands of the farmer”, says Román, “so that when they are deciding on a treatment program, they at least have the information to say ‘Hey, when I use these pesticides, they’re not just killing pests, they’re also affecting how disease is spread among all these pollinators’”.

If the bees don’t know what’s good for them, at least there are scientists like Román trying to figure it out on their behalf.

By Nathan Derstine


Created with images by Aaron Burden - "Large pumpkins in field" • Anita Austvika - "untitled image"