Another study adds to the buzz that a certain class of pesticides, called neonicotinoids, may be behind the bee-killing colony collapse disorder. But the findings have stirred up a hornet’s nest of objections from the pesticides’ manufacturer Bayer.

Harvard University biologist Chensheng Lu found a correlation between an imidicloprid contaminated diet and one of the symptoms of colony collapse disorder.

Neonicitinoids are pesticides chemically similar to nicotine found in tobacco. The pesticides, such as imidicloprid, clothianidin and thiamethoxam, are both sprayed on crops and used to treat seeds prior to planting. Discovery News reported on a study which suggested pesticide contaminated residue blown off from treated seeds during planting could be harming bees.

Some entomologists and conservationists also worry the chemicals find their way into the nectar and pollen bees feed on and products subsequently made from plants treated with neonicitinoids, such as corn.

Commercially available high-fructose corn syrup may contain residues of imidicloprid, contends Lu.