Researcher Christian Krupke said insecticides, which are highly toxic to bees, were found in each sample of dead bees collected over a two-year period. He said live bees at collection sites were exhibiting odd behavior, including tremors, uncoordinated movement and convulsions, which are all signs of insecticide poisoning. Krupke said the corn pollen bees were taking to hives was contaminated with neonicotinoids at levels high enough to kill bees if "sufficiently consumed," but talc exhaust from machinery contained levels up to about 700,000 times the lethal dose for bees.
Researcher Greg Hunt said there is no single cause of colony collapse disorder, which is devastating bee populations. Scientists believe other factors, including parasitic mites, habitat destruction, lack of food sources and poor quality food, could all contribute.