Tracking the flight of bumblebees, Canadian researchers hope to learn how pesticides can muddle their minds

Overlooking their delicate subject, the team’s fingers hold back an arrangement of wings and appendages. With a gentle touch, Amanda Liczner sets the tiniest of radio-frequency identification tags on the back of her charge, a common eastern bumblebee queen.

Dr. Liczner, a postdoctoral research fellow with the University of Guelph’s Raine Pollinator Lab, releases the bees into the Rare Charitable Research Reserve in Cambridge, Ont. The novel study will analyze their flight patterns after exposure to field-realistic levels of systemic pesticides, comparing the well-known neonicotinoid imidacloprid with the less studied diamide cyantraniliprole.

The problem with these two classes of pesticides, Dr. Liczner explains, is that they are systemic – “they can go through the entire plant.” Whether the treatment occurs as a seed coating before planting or a foliar spray before the flowering season, it will permeate the plant’s cells long after the initial treatment, even in the nectar and pollen.

It was with that condition in mind that the researchers set the experimental dosage to closely imitate what the bees experience in the field. The field-realistic levels were determined by working with the Pest Management Regulatory Agency’s own results, where they measured the amount of pesticide that honey bees were bringing back, in nectar, to the hive.

Dr. Liczner’s bumblebees were fed a sugar water solution containing those same concentrations of either imidacloprid or cyantraniliprole, and untreated sugar water for the control, for one week. “If these bees had been wild near a farm where they spray these pesticides, this is the concentration they would be eating.”

Initial findings allowed the researchers to visualize how even minor exposures, at levels deemed safe by Health Canada’s PMRA, have sublethal effects for bumblebees that may lead to a reduced brood size and decrease a colony’s survivability.