Purdue University could play a role in hardening European honeybees, the bees agriculture most depends on, against threats they face.

Greg Hunt, an associate professor of entomology at Purdue, sees great potential in uncovering secrets of bee behavior, then breeding lines of bees with traits that help preserve their bee colonies.

Recently, the best-known of these bee problems is colony collapse disorder, or CCD, a mysterious problem that apparently causes bees to leave their hives, never to return. This has caused some well-founded concern in other parts of the country, but there are no confirmed episodes of CCD in Indiana. In this state, Hunt said, the real threats are familiar enemies, such as the weather, which can knock out colonies in a few weeks, and varroa mites, which have afflicted beekeepers around here for about 15 years.

No researchers have pinned down the cause of CCD conclusively. "I'm not really worried about CCD, whatever it is. But ever since 1990, varroa mites ... have caused widespread die-offs of bees," Hunt said.

"All of the hives have mites at some level. We will never get rid of them," he said. If mite populations get too high in a hive, they can be killed with one of several pesticides. "If you don't control them, they're going to kill off your colony," he said.

In the last year, weather was the biggest problem Hoosier beekeepers faced. As Hunt explained, bees are vulnerable in many ways. A summer drought can reduce the flowers and other plants that bees depend on for nectar and pollen. But too much rain can be just as bad, "because when it's raining, bees can't forage," he said. Last winter, the unusually warm weather in December and January started queens laying eggs prematurely. Then cold weather kept worker bees near colonies' young to warm them; they were warm, but unfed.

"Our problem last winter was starvation," he said. "We lost about 50 percent of Purdue's beehives."

Prompted in part by CCD, there's a fledgling national effort to coordinate bee research, Hunt said, so that scientists aren't unknowingly duplicating one another's work. Purdue's greatest contribution to improving honeybees will likely come through work in breeding and genetics, he said.

An example from Purdue: While Miguel Arechavaleta-Velasco (who now works for the Mexican agricultural research service) was a Purdue graduate student, he found honeybees in Mexico that fought varroa mites on their own by grooming each other and chewing the mites.

Other strains of honeybees can smell varroa mites when they lay eggs in the honeycomb cells where young bees mature. Still others display beneficial "hygienic" behavior by removing dead or diseased bees from the hive - and, along with them, some of the mites or mite eggs.

Identifying hives where such behavior is common, where bees have innate defenses against the mites, and old-fashioned selective breeding could make a big difference. Lines of honeybees with demonstrated mite resistance could spread quickly as beekeepers propagate more and more colonies from those lines.

Entomologists at Purdue already have narrowed the genetic foundation of some anti-mite defenses to about 20 genes, Hunt said. Besides revealing more about bee genetics, identifying exactly which genes are responsible for bees' mite-biting defense could ensure that beekeepers don't accidentally nurture bee colonies that are more generally aggressive.

North American dependence on honeybees isn't as extreme as some of the most alarmist coverage of CCD would indicate, but a commonly accepted estimate is that about 30 percent of our food depends on bee pollination. None of the other 3,000 to 4,000 species of bees in North America pollinate human food crops as well as the ordinary honeybee.

"These other species of bees are just not as amenable to human cultivation," Hunt said. "Most are solitary bees," which means they can't be conveniently nurtured or transported in colonies of 50,000 or more, as honeybees can. Bumblebees are also good pollinators, and they form colonies, but only their queens survive over winter, so each colony starts from scratch each year, Hunt said.