There are quite a few theories about the cause: the draught, a new fungus, a virus. But there is also evidence that the culprit could stem from the mass-scale use of pesticides. Imidacloprid, a common insecticide used frequently to combat the infestation of the emerald ash borer in many states, has come under question. Developed in 1994, it has quickly become one of the most common pesticides, used not just for agriculture, but in golf courses, business and office complexes, parks, athletic fields, and residential areas.

The EPA report classifies imidacloprid as moderately toxic, warranting a warning label, though not restricting its use. It is classified as ?EUR??,,????'??highly toxic to honey bees,?EUR??,,????'?? though the levels of Imidacloprid found in the empty nests is below the bees?EUR??,,????'??? acute toxicity limit. That is, the bees are not being poisoned outright. Yet there is a theory that the pesticide is causing secondary effects on the bee?EUR??,,????'???s behavior which is causing their death. In the volume 21/2001 issue of the Journal of Pesticide Reform Eric Zeisstoff writes, ?EUR??,,????'??bees affected by imidacloprid suffer problems with orientation. Bees with a particular level of imidacloprid contamination at 500 meters from the colony did not return to the hive at all.?EUR??,,????'?? It is well known that honeybees depend largely on chemicals as a means of communication, so that the presence of the strong chemicals in pesticides can disrupt their normal means of orientation.

Richard H. Miller, of the The Columbus Dispatch responds that the environment is ?EUR??,,????'??being saturated with imidacloprid ?EUR??,,????'??? it is the chemical of choice in a no-win battle in the Midwest against the emerald ash borer, used lavishly on golf courses and various other applications.?EUR??,,????'??

Some people view the bees?EUR??,,????'??? disappearance as indicative of the safety of the presence of pesticides in the world?EUR??,,????'???s food. Miners kept canaries inside the caves to detect the presence of oxygen; when the canaries tipped over, it was time to leave. Honeybees are extremely sensitive to chemicals; the U.S. army is testing how to use honeybees as a sign of the presence of biological warfare.

Not everyone is convinced that pesticides are the source of the bee die-off. Eric Mussen, an entomologist and bee specialist at University of California Davis, believes malnutrition, caused by this being the driest year on record, to be the culprit. Though he hasn?EUR??,,????'???t ruled out the possibility, he feels there is not enough research to warrant any dramatic altering of imidacloprid usage.

Regardless of the outcome, this issue raises significant questions about how the EPA is testing pesticides. There is certainly a lack of research on the behavioral effects the pesticide is causing, other than simply the acute toxicity levels. Further, it would be important to test different forms of the pesticide (granular vs. spray vs. injectible) to determine if one form is safer than another. If imidacloprid is source of this large bee die-off (ironic, as so many food sources depend on their pollination to survive) the implications could be grave.