Scientists believe a combination of factors contributes to Colony Collapse Disorder, including habitat loss, parasites and viruses. But recent studies point to a common group of pesticides called neonicotinoids as a significant factor.
Paul Towers is with the Pesticide Action Network North America. He says current science suggests even low levels of pesticides can cause serious damage to bee colonies:
TOWERS: "While they may not kill the bees outright they suppress or depress their immune system, and make them vulnerable to a whole host of other factors, these other pathogens, the varroa mite, chief among them, and poor nutrition. It's this combination of factors that puts the honeybees at greatest risk."
Studies of corn grown from seeds treated with these pesticides show that the chemical does work its way into the pollen, as well as the soil and nearby untreated plants.
Several European Union countries have already limited use because of the risk to honeybees. A resolution introduced into the state Assembly asks the California Department of Pesticide Regulation to review the science.
Many California crops rely on bees. The almond industry alone rents about 1.5 million honeybee colonies each year.