Researchers led by the US Department of Agriculture's Bee Research Laboratory head Dr Jeffrey Pettis claim that even minute doses of the chemical render honeybees more vulnerable to infection by the fungal parasite Nosema.
"We believe that subtle interactions between pesticides and pathogens, such as demonstrated here, could be a major contributor to increased mortality of honeybee colonies worldwide," the paper states.
Imidacloprid, made by Bayer CropScience, is an active ingredient in commercial horticultural products Admire, Gaucho, Intercept, Merit Turf and Provado.
But Bayer CropScience representative Dr Julian Little said: "Jeff Pettis's studies were carried out in the laboratory and not the open air. Bee health is really important, but focusing on pesticides diverts attention away from the very real issues of bee parasites and diseases."
NFU horticulture adviser Dr Chris Hartfield said: "Pettis's findings are another piece of the puzzle but don't tip the balance. Bodies with an anti-pesticide agenda want to take a precautionary or risk-based approach, but there should be a weight of evidence before a ban is considered and that certainly isn't there."
Charity Buglife has previously called for the chemical to be banned, a plea that was reiterated by the charity and the British Beekeepers Association last weekend.