[Stinging Insects] Steadily Spreading

Even as thousands of honeybees so vital to agriculture are mysteriously disappearing, the harder-to-handle Africanized honeybee is spreading farther into the United States — even into hard-winter climates — frustrating pest control operators and confounding researchers.

Gloria DiGrandi-Hoffman leads a team of researchers at the Carl Hayden Bee Research Center in Tucson, Ariz. She’s been studying bees and pollination for almost 30 years, and another dozen years focusing on Africanized honeybees, and their steady spread into the United States from South and Central America.

A BIT OF BEE HISTORY. Africanized honeybees — often mistakenly referred to as “killer bees” by the media and horror movie fans — came to the United States in 1985 in a shipment of freight. The bees first swarmed into America a few years later, establishing colonies in South Texas, and they eventually moved into much of the southern U.S.

And now, thanks mostly to truck and train transport, the bees have spread into Arkansas, New Mexico and Texas, with the indefatigable insects no longer stymied by temperatures that regularly dip below freezing.

WHAT’S THE DIFFERENCE? Sure, to the uninitiated, a bee is a bee is a bee. But, to someone like DiGrandi-Hoffman, who has devoted so much time studying lapidary bloodlines, the genetic differences between Africanized and European bees are legion.

The main — and hugely important — difference between an Africanized and a European honeybee is one of simple timing: An Africanized queen bee matures about a day earlier than her European counterpart, giving her an edge in breeding time, DiGrandi-Hoffman said.

And queens of both stripes seem to prefer the genetics of African drones to Europeans. If a queen mates with an even number of Africanized and European drones, her offspring will be 70 percent Africanized, DiGrandi-Hoffman said. Those offspring with the Africanized bloodlines then mature faster, leading to the so-called Africanization of a colony.

“That fixes the African genealogy in that colony,” DiGrandi-Hoffman said. “Because of their earlier emerging time, the colony won’t revert back to a European colony. Over time, there becomes this irreversible Africanized process.”

And, as far as the bees are concerned, none of this is bad. The Africanized bees are more are more resistant to disease and temperature changes; they can breed all year and can forage longer and earlier than European bees. But for pest control operators, the Africanization of a colony can be a very bad thing.

Africanized honeybees have “pretty intense nesting behavior,” which is difficult to manage, she said. And while their reputation for swarming at random and stalking prey is unwarranted, they are more apt to swarm defensively, claiming a larger territory as their own than European bees.

“You have to have them in places where there aren’t people walking around all the time,” she said, adding that the bees can be managed by professionals in farms, and still can be used to pollinate crops.

WHAT IS TO BE DONE? DiGrandi-Hoffman said she and her team of researchers have to be diligent to ensure genetic purity in their honeybee populations; any queens allowed to freely mate would likely become Africanized.

“Beekeepers are really the front line of defense,” she said.

PCOs, though, need to be aware that they are the best people available to eliminate nesting sites or potential swarms.

“If you have a swarm of bees in your house…they need to be removed by professionals,” she said. “It’s similar if you knocked down a hornet’s nest, or a nest of yellow jackets. It’s the same sort of thing.”

But whatever PCOs and beekeepers do to control the spread of Africanized honeybees, DiGrandi-Hoffman said, the species isn’t likely to disappear anytime soon.

“It seems that it’s found a survival strategy as it’s hybridized with European (honeybees),” she said. “It’s been quite surprising. They’ve been able to adapt.”

The author is assistant editor of PCT magazine.

How to Best Control a Swarm of Africanized Honeybees

When Africanized honeybees swarm into a new area, their first matter of business is finding a place to live. If they like where they’ve landed, the bees will lay down honeycomb and start building a colony, said Gloria DiGrandi-Hoffman, the lead researcher at the Carl Hayden Bee Research Center in Tucson, Ariz.

DiGrandi-Hoffman recommends watching the bees for a day or two to see if they do start to put down roots. Many times, they will land, not like the proposed home site and leave, she said. If they do start to lay down comb, she said a soapy water mixture works well to desiccate the bees.

But, she said, “if it’s an established colony, you need pesticide to prevent swarm,” and something with a high residual value to control foraging bees returning to the hive.