Honeybees are vanishing from their hives without leaving a trace. The phenomenon known as “Colony Collapse Disorder” occurs when worker bees abruptly disappear from a beehive. It was first reported in the United States in 2006. Since then, continued decreases in honeybee populations are making the disorder a prevalent issue threatening food production both locally and in the country.

Symptoms of the disorder include the rapid loss of adult worker bees, few or no dead bees found in the hive, and only a small cluster of bees with a live queen present. “The demand for honeybees is growing, and the supply is sharply decreasing,” said Matthew O’Neal, an assistant professor of entomology at Iowa State University.

O’Neal said the demand for honeybees and the lack thereof will cause problems for the honeybee industry. He said the pressing demand is going to raise the cost beekeepers charge and farmers have to pay, and eventually, consumers will feel the price hike. “It’s just a matter of time,” O’Neal said. “If we don’t adjust that relationship somehow, it’s going to affect all of us.”

Honeybees are directly and indirectly responsible for pollinating one-third of the food humans consume. Dave Irvin, president of Eastern Central Iowa Beekeepers, said Iowa was hit by colony collapse disorder badly a year ago, and beekeepers have been trying to rebuild since.

In Johnson County and counties close by, Irvin said there are beekeepers who experienced up to 50 percent colony loss. “After the winter, you find dead bees in the hive that have starved,” Irvin said. “But with this, the bees were all gone for no apparent reason, and the honey was all still there.”

Joel Coats, an ISU distinguished professor of entomology, said losses because of this year’s harsh winter have been greater than usual, with some beekeepers losing 75 percent of their hives. According to the U.S. Department of Agriculture, the United States had as many as 6 million honeybee colonies in 1947. That number dropped to roughly 4 million in 1970 and 3 million in 1990. Today’s number is approximately 2.5 million colonies.

“Many fruit and vegetable growers depend heavily on bees,” Coats said. “And they are very concerned about the availability of enough bees to pollinate their crops.” O’Neal said there isn’t just one cause of the decline, but numerous “stressors” honeybee populations are facing. Some of the decline contributors include pesticide exposure, disease, invasive species, loss of habitat and habitat fragmentation, and a lack of diverse food sources.

Neonicotinoids, the world’s most widely used insecticide, has been scrutinized for recently killing honeybees. “When honeybees are exposed to neonicotinoids, their immune system is compromised,” O’Neal said. “And they’re more prone to being infected by disease.”

This particular insecticide is based on nicotine — a substance toxic to insects. In extreme cases, neonicotinoids are altered to make the chemical longer lasting, and therefore making it significantly more toxic. State apiarist Andrew Joseph said the problem with pesticide use in farming is the airborne toxic clouds that come with the modernization of air-driven planters. When planting a seed, it goes through a mechanism in which tufts of air are released. Problems arise when the air mixes with chemicals from the pesticide treatment, putting the chemical into the air for bees to breathe.

Joseph said we’re at the point where the damage of pesticides on honeybees are known; the debate is now what we can do about it. “Our industry is at a critical time where beekeepers are having extremely high losses that aren’t sustainable,” he said. “There’s a lot of room for improvement.”

ISU Extension Professor Donald Lewis said we need to avoid “one size fits all” solutions in solving the problem of honeybee decline. “Insecticides may be the one impact on honeybee population decline we can easily regulate,” Lewis said.

Though there have been efforts in Europe to ban neonicotinoids, the threat colony collapse poses to food supply around the world has yet to be solved. But there is some hope, O’Neal said. He said since the 1990s, there has been a remarkable increase in what scientists know about honeybee biology and ecology.

“There are thousands of other bee species,” O’Neal said. “We’re starting to learn how to manage them to use them as pollinators; some are even more efficient.”