Bee aware of their impact:

• Bees must collect nectar from 2 million flowers to make 1 pound of honey

• A hive of bees fly over 55,000 miles to bring you 1 pound of honey

• It takes 12 bees their whole lifetime to produce 1 teaspoon of honey

• Bees are the only insects that produce food eaten by man

• Everything the honey bee produces can be used by mankind. Examples include honey, beeswax, pollen, propolis, royal jelly and Apitherapy

• An estimated 80% of crop insect pollination is accomplished by honey bees

• The number of honey bee hives has declined in Ohio from a high of 330,000 in the 1940s to 32,109 colonies in 2010.

Source: Central Ohio Beekeepers Association

where are all the bees?

Recent studies show insecticides may be a factor in the disappearance of bees

by Amy Beth Graves

Whether you’re sitting in your back yard or watching a local baseball game, you’ve probably noticed there are not as many bees buzzing around and that has farmers and agriculture experts concerned. In Ohio and across the country, farmers rely on bees to pollinate their crops.

“The value of bee-pollinated crops in Ohio was $216 million in 2010,” said Reed Johnson, an Ohio State University assistant professor in the entomology department. “Without pollination, pumpkins, apples and other pollinated fruits would not be able to grow.”

Many are looking to Johnson and his colleagues for answers on why the bees are disappearing. The disappearance is known globally as colony collapse disorder, which means honeybees leave their hives and don’t return. Annual surveys show Ohio has been losing about one third of its bee colonies since 2006, Johnson said. In 2010, the state lost about 40 percent. As far back as 1969, Ohio State University has been examining nutrition, mites and pathogens and their potential roles in colony collapse disorder.

Recent studies indicate widely used insecticides may be contributing to the disappearance of the bees. The “neonicotinoid” pesticides are used on everything from field crops to trees to homeowner yards and are toxic to insects and safer for people than previous pesticides.

In one study, bumblebee hives were placed in enclosed fields with some sprayed with the insecticide and others not sprayed. After six weeks, the sprayed hives were 8 percent to 12 percent smaller than the nonsprayed hives and produced 85 percent fewer queen bees.

Another study focused on honeybees, which were exposed to the pesticide and tagged with tiny radios so scientists could track them. The bees were released more than half a mile from their hive. Bees exposed to the pesticide were 10 percent less likely to make it back to their hive while in familiar territory and 31 percent less likely in unfamiliar places, according to the study.

More research needed

The studies seem to indicate the insecticides are contributing to the dwindling number of bees but more research needs to be done, Johnson said.

“With regard to the honeybee (study), the experiments were done at levels above what most bees experience in nature. The doses were very high. The bumblebee study that is out, they did use lower doses, though,” he said.

“Every time there is a new study, people jump at it. We don’t know what the answer is yet. Pesticides probably play a role but what role they play is not clear.”

The insecticides could be making the bees weaker, meaning they are more susceptible to viruses, parasites and Varroa mites, which keep deformed or weakened bees from emerging from their developmental stage, Johnson said.

“Varroa mites are still a major problem. It’s possible that it’s not just one thing but several things working together,” he said.

Other factors

Erratic temperatures are another problem for bees. When temperatures rise, the bees commit to raising their offspring and if the temperatures plummet, they die off. They also dip into their honey stores during cold snaps, meaning they may run out and starve later.

One way for the bees to heal is a strong, productive nectar and pollen season in the fall so they can recover their strength and stamina before going through another winter, said Ohio State University apiculture specialist Jim Tew.

While scientists are still divided on what exactly is causing the bees to disappear, at least they can now rule out some possibilities, Johnson said.

“And that is progress,” he said.

All photos courtesy Ohio State University Communications and Technology.

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