Honeybee Colonies Are Still Declining. What's Hurting Their Health?

As there continue to be reports of honeybee colony loss, we get the latest from a researcher who has been looking at the causes of the decline. University of Maryland scientist Dennis vanEngelsdorp talks with Here & Now's Robin Young about the factors impacting bee health.

On the worst honey bee die off in over a decade

"We lost a lot of colonies this winter and we’re still trying to figure out what was extraordinary about this winter that caused it. We think that some of the old standards are still at play.

We’ve always thought that pesticides are important. [Also] Varroa mites -  these large parasitic vampire-like mites that feed on the bees that pass on viruses. But this last year, I think if you remember last year we had a lot of flooding, we had a lot of fires, and we had a lot of climate events. We think that these things may have contributed, but still think that the leading cause of the loss are Varroa mites – these mites that were introduced into the country in the 80s and they’ve been here a long time. The products we have to control them aren’t working as well. ...The viruses they transmit have changed and become much more lethal."

On pesticides affecting the bee population

"When we talk about bees, are we talking about honey bees or the 4,000 native bees that we have in this country? When it comes to honey bees, honey bees are social insects – that means that they live sort of as a colony. So we think of the whole unit of 40,000 bees as being one organism. And that organism has a lot of fat, it has a lot of extra bees, which means it can take a pesticide kill and still be just as healthy.

Because you can lose 30 percent of bees in a colony and that colony is still able to survive. However, these native bees are solitary or very small colonies. If they get hit by pesticides, then you see the long term damage to the population… So we think pesticides certainly play a role, they probably play a much more pronounced role on native bees than on honey bees."

On mite control

"There’s several things we can do. First of all, beekeepers need to be aware of the problem. So they have to be sampling regularly. We process thousands of samples a month, and beekeepers can do this at home too, where you count the number of mites in your colony. And as soon as you reach a threshold, you need to treat. Actively watching mite levels, making sure they’re not getting too high, and controlling them right away I think is important for all beekeepers to follow up on.

...There was a time where you treated your colony and you knew you treated it once a year, and it worked. But those days are over. Getting that information out to beekeepers is really important."

On colony treatment

"You need to implement at least three different strategies. You can apply chemicals - a synthetic chemical to your colony.  [We] also have organic acids and essential oils that you can apply at the right temperature that will knock mite populations down.

...You can make the floor of the colony a screen so that it lets mites that just drop off of bees naturally drop out of the colony and can’t get back in. There are other physical things you can do while you’re managing your colony to keep mite populations low."

On breeding resistant bees

"I also think it’s important to note that there’s a group of beekeepers out there that are very nobly-minded, and these are the ‘no treatment’ beekeepers. These are the beekeepers who believe that if we leave the colonies and honey bee colonies alone that they’ll survive. And in fact, in the forest, when bees are in isolation and there are no colonies around, this strategy probably works.

However, because most colonies are managed in areas that are very densely populated, if you have 10 colonies and you let nine die in the hope that the one surviving colony you can breed from and save the American bee industry, that’s a noble cause. But unfortunately, as those nine colonies die, we’re pretty sure that the mites in those colonies are spreading like these mite-bombs in the landscape, invading neighboring colonies.

...If you want to breed resistant bees, which is a very good idea and there’s been success at doing it, you still need to manage the mites and control the mites once you’ve identified that the colony is not breeding stock."

On concern of losing beekeepers

"I think that’s the greatest fear. …Most beekeepers in this country are small-scale, backyard beekeepers. I really do recommend that everyone take the one opportunity to open a hive and hold that frame of bees in your hand on a sunny day, and the birds are singing, and you see these 30,000 workers working in unity, making this liquid gold, and there’s the queen. It’s an exciting and awesome experience to open a colony of hives.

Ninety percent of the colonies are managed by only five percent of the beekeepers – these are the commercial beekeepers. These are the last nomadic farmers in America. They take their bees and they put them on trucks, and move them up and down either the east or west coast. Most of them in February will go to California to pollinate the almonds, and put their bees back in trucks and move them around the country, just pollinating fruits and vegetables. That group of beekeepers, multi-family generations, so their great grandfathers did it and now they’re doing it. These family businesses I think are the ones we’re most worried about. Because if they go out of business, it’s really hard to replace them. You need to be a truck driver, you need to be a mechanic, you need to be a beekeeper, you need to an accountant. It takes a special kind of person and we worry that if we lose too many of those big commercial beekeepers, then we won’t be able to pollinate all those crops that we produce in this country."

On repopulating colony losses

"It’s a unique crop. When you have a dead colony and a living colony, you can go to that living colony, split it in half, buy a queen, which can arrive in the mail, add you queen bee to the colony that doesn’t have a queen, and you have two colonies again. So you can split to reproduce your colony losses very quickly. Even though a beekeeper may lose 50 or more percent of colonies over the winter, by next summer they have made up all those losses and are still at the same level.

Of course you can’t do that for free. There’s a loss in production, you have to spend more time doing it. So that’s where the economic burden, especially for these commercial beekeepers, comes into play."

On issues affecting the bee industry

"Increasingly, we’re seeing land that beekeepers used to be able to access, like federal forests, that are no longer available for bees. We’re also seeing a lot of farm policy is encouraging mass plantings of crops that are treated with pesticides. I think there are policy regulations we can change in order to encourage best practices that help honey bees and all pollinators. It’s important that we get some new tools to beekeepers that help control mites. And we have to really think about wise pesticide use across the country – do we really need to use it?"

Derek J. Anderson adapted this story for the web.