University of Minnesota professor Marla Spivak studies honeybees. She's fighting a parasite that has killed up to half of all North American bees in the last year.

Spivak leads a bee-breeding program that produces queen bees that remove larvae infested with Varroa sp. mites from their hives. (The mites suck blood from the bees, especially developing ones, weakening them and shortening their lifespan. Infested emerging bees may be missing wings and legs. And an untreated infestation can kill an entire honeybee colony.)

Humans used two chemicals against the mites for years, but the mites have recently become resistant to both and have made a big comeback, destroying honeybee colonies across the country. But beekeepers using Spivak's queen bees have experienced only minor losses.

Don't think humans depend on bees? Think again. Honeybees pollinate about a third of our diet and dozens of agricultural crops. The mite problem affects even the dairy industry, since the cattle feed crops alfalfa and clover are honeybee pollinated, not wind pollinated like most grasses.

Many, many "pest" species are developing resistance to the chemicals we use to control them. Do you worry about this trend? Do you see alternatives to chemical pest control? Would you be willing to pay more for food products that are chemical free?