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It is spring in Canada, and the buds and bees are coming back – but so are chemicals that initial research shows may affect the insects’ memories and navigation

It is a September day in Cambridge, Ont., and this common eastern bumblebee has found some goldenrod to forage on. On its back is a radio frequency identification tag left by the charitable research institute that owns the plots in the background.

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.

This metallic green sweat bee, foraging on a blueberry farm in Barrie, is likely a female Agapostemon sericeus. A related species, Agapostemon virescens, is the official bee of the City of Toronto. Bees are a critical part of Ontario’s ecosystems, and they are in decline: Species such as the rusty-patched and gypsy cuckoo bumblebees are endangered, and others are at risk.
In Cambridge, the researchers tag bumblebees, collected in tubes, with devices smaller than a quarter. They want to know whether pesticides impair the bees’ ability to fly and remember where to go. Initial findings suggest even small amounts of pesticides deemed safe by Health Canada could affect the bees’ decisions, making the difference between large and well-fed broods and smaller, vulnerable ones.
Amanda Liczner of the University of Guelph is lead researcher on the project. On the grass beside her, each plastic container represents a bee that has been tagged and released. The trackers will also give Dr. Liczner an idea of where the bumblebees hibernate, something only the queens do. The rest of the colony dies each fall.
In Markham, a black swallowtail drinks from wild teasel. Butterflies are also important pollinators, and like bees, they are under pressure from habitat loss, pesticides and other factors. Last summer, the once-ubiquitous monarch butterfly joined the endangered list kept by the International Union for the Conservation of Nature.
About a third of global crop production relies on pollinating insects. In Ontario, they are vital to apple orchards – like the one in Barrie where this mining bee is feasting – and summertime staples such as strawberries, peaches and grapes. By tagging bumblebees, Dr. Liczner and her team hope to get new insights so the bees, and by extension humans, can feed and thrive.

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