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They came, they conquered, and they stayed, but you’d hardly know it if you weren’t an entomologist.

After years of media hype, Africanized hybrid honeybees, once commonly called “killer bees,” have established themselves in urban areas to the point of genetic domination among wild European honeybees — also an introduced, if more mellow, species. Biologists, who regularly test local bees for genetic makeup, estimate that three-fourths of feral honeybees in San Diego County’s urban areas are now Africanized, but to the surprise of beekeepers and scientists, the newcomers have been relatively polite neighbors.

“We may have overhyped it,” says Dr. David Kellum, San Diego County’s entomologist, “but we had to stress the danger level to get people’s attention because these bees really are measurably more aggressive.”

Local beekeepers have learned to contend with this new member of the environment. Beekeepers’ colonies regularly become “infected” with Africanized genes, a situation observable by heightened aggressive behavior in the bees, which may pounce on a beekeeper at the slightest disturbance. Africanized bees produce honey just like the European subspecies, and while some beekeepers “run” Africanized bees, the insects’ behavior can make them hazardous to work with. Where an unprotected person may get stung 10 times by a disturbed European colony, an Africanized colony might deliver 1000 stings.

“You open up the hive and they jump all over you,” describes Chuck Nickels, part owner of San Luis Rey Apiaries in Valley Center.

Beekeepers frequently “requeen” infected colonies, removing the Africanized queen and replacing her with a female purchased from a professional breeder, most of whom are based in genetically clean zones, such as Northern California or Hawaii. The colony’s worker bees constitute the bulk of the hive’s 50,000-odd bees. Workers can live for several months, while queens may live for three years or more. Thus, within weeks or months of requeening, all the Africanized offspring will have died off, leaving the colony clean and the pure queen seated on the throne.

But Nickels, who works between 4000 and 5000 hives, usually kills the entire colony when he observes Africanized behavior.

In the United States, Africanized bees have killed 23 people by some reports since entering Texas from Mexico in 1990. In California, one person, a Long Beach man, has been killed by Africanized bees since 1994, when they are believed to have arrived in the state.

“By stirring up the media interest all those years, we’ve alleviated the potential impact and disaster,” says Kellum.

Bee advisories were distributed in Southern California in the 1990s in nine languages to elevate public awareness, says Dr. Eric Mussen, an apiculturalist at the University of California, Davis. Such campaigning and public education did not occur in Mexico, he says. The result was 175 deaths between 1988 and 1995, prompting the popular name “killer bee” in movies, on TV, and among the media.

African honeybees first appeared in the New World in 1956, in São Paulo, Brazil, as researchers attempted to breed their genetic material into local honeybees to produce a sturdy strain more appropriately suited to the local climate. The African bees escaped and “swarmed,” breeding with local honeybees and foraying outward in search of new habitat, and the aggressive insects commenced on a northward journey of sometimes 250 miles per year. The bees reached Mexico in 1985. Meanwhile, dispersal slowed in the desert region of northern Mexico, and the Africanized bees arrived in Texas in approximately 1990. In California, the bees have moved northward at a rate of approximately 50 miles per year. The insects have been found as far north as Tulare County in the Central Valley and Santa Barbara on the coast, but for the past three years, says Mussen, northward movement has apparently ceased.

Kellum says that identifying Africanized bees’ hives by observation may not be immediately possible. A colony of bees may move into an attic or a backyard and demonstrate a gentle temperament for several weeks. Behavior changes dramatically once they have built up a honey store to protect or established a nursery of young to guard. While all bees may respond aggressively to intruders, and Africanized bee venom is no more potent than that of other bees, Africanized bees are more aware of their surroundings. They may react to vibrations 50 feet from their hive and may chase fleeing targets for a mile or more.

The most recent such incident in California occurred in early June in Stoney Point Park in Chatsworth, north of L.A., when a group of teenage boys who had stumbled upon a hive was attacked by a swarm of bees. Their pet dog was killed. Also in June, a 72-year-old bulldozer operator in Graham, Texas, was attacked and stung thousands of times, according to local authorities. Rescuers hauled the man, who survived, into a truck, which the bees reportedly chased for several minutes.

Alan Mikolich, a commercial beekeeper who works 700 to 1000 hives in San Diego and Imperial counties, finds infected hives every week or two, he says. He recalls one such instance in early June.

“I was going through, opening the hives, and they swarmed out and stung me about ten times immediately.”

He retreated, then returned wearing protective clothing and carrying a bucket of soapy water to douse the bees — a trick that coats the insects with suds and effectively drowns them. Emptying a can of ether into the hive will also do the trick. Last year, Mikolich, who has kept bees commercially since 1985 and prefers to work in shorts and a T-shirt, killed seven of his colonies.

James Gibbs, owner of Chaparral Honey in Valley Center, has killed only a dozen colonies in the past 5 years, he says. The 83-year-old has kept bees for 40 years and reports a limited influence from Africanized bees on his colonies. He prefers to requeen those that “turn mean.”

Last fall, San Luis Rey Apiaries’ Chuck Nickels found just three of his hives infected upon bringing them home from the Imperial Valley’s alfalfa fields. Indeed, while local entomologist David Kellum’s research in Escondido, San Diego, Oceanside, and many other cities has revealed a rate of 75 percent Africanization, the Imperial Valley is believed to bear a lower Africanized density, closer to 30 percent, according to UC Davis’s Mussen.

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