For related articles and more information, please visit OCA’s Genetic Engineering page, Millions Against Monsanto page and our Honey Bee Health page.

Bumblebees exposed to controversial pesticides collect just half the pollen they would otherwise harvest, according to new research, depriving their growing young of their only source of protein.

The work has been hailed as important by independent scientists because it sheds light on how the neonicotinoid pesticides can harm bees.

“Pollen is the only source of protein that bees have, and it is vital for rearing their young,” said Professor Dave Goulson, at the University of Sussex and who led the study. “Collecting it is fiddly, slow work for the bees and intoxicated bees become much worse at it. Without much pollen, nests will inevitably struggle.”

A two-year EU ban of three neonicotinoids, the most widely used insecticides in the world, began in December, following research that showed harm to honey and bumblebees. The neonicotinoids are “systemic” pesticides, being applied to seeds so that the chemical spreads within the plants. Over three-quarters of the world’s food crops require insect pollination, but bees have declined in recent decades due to loss of flower-rich habitat, disease and pesticide use.

Goulson’s team tested one of the three, called imidacloprid, at low doses aimed at replicating those encountered by bees in fields. They attached tiny electronic tags to bees so their movements could be tracked and each bee was weighed on its way in or out of the nest.

Bees exposed to the neonicotinoid brought back pollen from only 40% of trips, while unexposed bees carried pollen back from to 63% of trips. Furthermore, exposed bees that did return with pollen carried 31% less than unexposed bees. Overall, the nests exposed to the pesticide received 57% less pollen. The ability of bees to collect sugary nectar did not differ significantly between the bees. The work is published in the peer-reviewed journal Ecotoxicology.

Hannah Feltham, at the University of Stirling and another member of the research team, said: “This work adds another piece to the jigsaw. Even near-infinitesimal doses of these neurotoxins seem to be enough to mess up the ability of bees to gather food. Given the vital importance of bumblebees as pollinators, this is surely a cause for concern.”