Evidence is emerging that singles out one particular class of insecticides, a widely used group of chemicals known as neonicotinoids, as the prime suspect in the death of bee colonies.

An epidemic that affects this country's plant materials can be attributed to the disappearance of honeybee colonies, a phenomenon dubbed colony- collapse disorder, or CCD. We depend on honeybees to pollinate a tremendous number of food crops.

Bees pollinate not only the vegetables and fruits that we eat, but clover for the cows, goats and sheep that make milk and cheese, and cotton plants for the clothes we wear, according to author Annie Woodhull. They are responsible for one out of every three mouthfuls of food we eat.

The prevailing view was that a variety of factors, from pesticides to parasites and pathogens, combined to bring about these collapses. Since then, evidence is emerging that singles out one particular class of insecticides, a widely used group of chemicals known as neonicotinoids, as the prime suspect in the death of bee colonies.

The mounting case against the neonicotinoids has led to bans in several countries and, most recently, a two-year suspension of their use throughout the European Union. Italy, which unilaterally banned neonicotinoid use on corn in 2009, saw a dramatic increase in bee colony survival in the same year. As a result, the ban remains in effect there despite industry opposition.

Here in the U.S., the Environmental Protection Agency has not taken any of the neonicotinoids off the market. The agency's review process for such actions typically takes years, so it's uncertain as to when or whether these chemicals may be removed from use.