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You don’t want your kids to smoke, right?

Turns out, nicotine-like substances are harmful to bees as well, especially when it comes to producing more queen bees – the ‘super moms’ of the colonies.

The fate of bees and other insects is important because about a third of the food we eat, one bite in every three, depends on insects. Insects, such as honeybees and bumblebees, help our food plants reproduce by transferring pollen from flower to flower and plant to plant.

But just like humans, these insect pollinators need to eat, and as we cover more land with agriculture, these insects end up eating pollen from our crop plants. The problem: pollinator numbers are falling. The reasons behind these declines are complex, but there is growing concern that the chemicals we put on plants, especially as part of our industrial agricultural system, are playing a role.

RAPESEED FIELD. PHOTO: BAUM IM FELD, PETR KRATOCHVIL

RAPESEED FIELD. PHOTO: PETR KRATOCHVIL

One such chemical is imidacloprid, the second most widely used agrochemical in the world, and a neonicotinoid pesticide. Neonicotinoids are chemically similar to nicotine and, ironically, were welcomed as safer alternatives to earlier spray pesticides because they are applied to seeds, roots or trunks, greatly reducing human exposure.

But these pesticides are carried by sap all over plants and end up in the pollen and nectar that pollinators use for food. Eating such chemicals makes it harder for pollinators to raise their babies, especially their queens. Bumblebee colonies exposed to imidacloprid produce 85% fewer queens, and since queen bees single-handedly establish new nests, one less queen equals the loss of a whole colony.

The trouble is, scientists don’t know why this happens. Now new research from the U.K. may be shedding light on how imidacloprid harms pollinators. U.K. researcher Hannah Feltham and colleagues spent two weeks feeding bumblebees (Bombus terrestris) pollen and nectar laced with doses of imidacloprid commonly found in widespread flowering crops like oil seed rape (Canola).

Then they spent four weeks following the bees around the gardens of Stirling, Scotland. Imagine, keeping track of the comings and goings of bees! To do it, the researchers used Radio Frequency Identification(RFID) tags to track when pesticide-exposed and pesticide free-bees (controls) left their colonies and returned with food.

The researchers found that bees exposed to imidacloprid went out looking for food 23 per cent less frequently, and when they did go out, they brought back 31 per cent less pollen per hour than controls. The researchers could not figure out why bees exposed to pesticides had trouble bringing back pollen. These bees could bring back as much nectar as controls and did not seem to get lost more often. But whatever the reason, colonies exposed to imidacloprid got less pollen – the main protein source for bumblebees – and a food that is particularly important for feeding young, especially developing queens.

Worse, the bees’ food-finding ability was still affected four weeks after exposure to the pesticide stopped.

The bottom line: This research adds to a growing list of studies that question the wisdom of using neonicotinoid pesticides on agricultural plants that are increasingly used by pollinators for food (and that are eaten by humans too, by the way). The sultry days of summer are a ways off, but when they arrive and the air is (hopefully) filled with the low buzz of bees flitting from flower to flower, remember that although there may not seem to be a connection between the bees in your garden and the Canola oil in your dinner – there is.

The choices we make, as consumers, as voters, and as nations, have impacts on the world around us.

Deborah M. Buehler is an ecologist, an editor and a writer in Toronto. Follow her on Twitter and catch up on all her Wild City posts here.

Source: Ecotoxicology 

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