Killer Bees Terrorize California Town
Africanized bees have spread to northern California and may have been responsible for severe stings and the death of two dogs. →
A community in northern California is returning to normal after a weekend attack by suspected ‘killer" bees left several people stung and two dogs dead.
The attacks began when beekeeper Arthur Janke tried to move a hive in his backyard in Concord, about 20 miles northeast of Berkeley. The bees in the hive "went berserk," stinging him through his bee suit. They attacked his parents and spread out into the neighborhood, stinging the man who lives across the street from Janke 16 times, descending on a mail carrier, attacking pedestrians and swirling around cars.
Janke's neighbors returned home that evening to find their two dachshunds in the backyard, covered with stings - at least 50 each, by a veterinarian's count. Both dogs died. (This piece in SFGate includes a number of remarkable first-person accounts of the scene as the bees attacked.)
By end of day Sunday, police confirmed that the swarms were no longer present in the community, but Concord police spokesman Corp. Chris Blakely told the East Bay Times, "as it gets warmer, you'll see more and more of the isolated (bees), and there's no doubt, they are very, very aggressive. So while the swarms are gone, it's not something that's going to go away entirely overnight."
The working theory is that the bees were Africanized honey bees - a hybrid of European and African honey bees. African bees were imported into Brazil in 1957 to improve honey production, and have been spreading steadily north since then, entering California for the first time in 1994. Once in the United States, they have mated with domesticated European bees to create ‘Africanized' bees.
While African and European honey bees are physically similar, the former are far more aggressive, and can chase a human or animal for a mile or more, according to this University of Florida fact sheet. That's a behavioral adaptation to an environment in which predators such as honey badgers pose a real threat; in contrast, European honey bees have been selectively bred over generations to be more docile.
It seems likely that a colony of aggressive Africanized bees either mated with or displaced the European honey bees in Janke's hive. Although the San Francisco Chronicle reported officials at the Contra Costa Mosquito and Vector Control District as saying that three dead Concord bees they examined didn't appear to be Africanized, studies have shown that once more than 50 percent of a colony consists of Africanized bees, the entire hive becomes more aggressive. DNA testing is being conducted on a number of the bees to establish their genetic makeup.
The attack came shortly after scientists confirmed through genetic tests that Africanized bees had been present in the Bay Area since at least 2014. However, it doesn't necessarily follow that the region's bees are on an inevitable march toward hyper-aggressiveness: The relatively cool weather in northern California may counter the advantages that African bees enjoy in warmer climes, and there's some indication that with repeated hybridization, Africanized bees become less aggressive over time.
Africanized honey bees look much like their European counterparts, but frequently exhibit far more aggressive behavior.
The global pandemic that is killing bees worldwide is man-made, with humans fueling the spread of tiny disease-carrying mites, a new study finds. At the center of it all is the Varroa mite, which can harbor the virus for the bee-killing disease known as deformed wing virus, or DWV. The new study, published in the journal Science, found that European honeybees are the source of cases of DWV infecting hives worldwide. "Varroa mites feed on honeybee hemolymph or 'blood,'" lead author Lena Bayer-Wilfert, a senior lecturer in molecular evolution at the University of Exeter's Center for Ecology and Conservation, told Discovery News. "They can get infected or contaminated when they feed on infected honeybee larvae and can then in turn pass on the virus to new bee larvae."
The mites have been inflicting a devastating double blow to bee colonies. They feed on bee larvae, a practice that itself is clearly damaging. Even worse, if the larvae were previously infected with DWV by another mite, the feasting parasite could then spread the virus to other larvae as well as to adult bees. For the study, Wilfert and her team sequenced data of DWV samples across the globe from both honeybees and the mites. They additionally tracked the occurrence of the mite worldwide. The researchers then used that information to reconstruct the spread of DWV. They found that the epidemic largely spread from Europe to North America, Australia and New Zealand. There was some two-way movement between Europe and Asia, but none between Asia and Australasia, despite their closer proximity. (Australasia refers to Australia, New Zealand, the island of New Guinea, and neighboring islands in the Pacific Ocean.) The scientists also looked at samples from other species suspected of transmitting the disease, including different species of honeybee, mite and bumblebees, but concluded that the European honeybee was the key transmitter.
Look closely and you will see the mites attached to some of these honeybees. The researchers found that how the host bees and their mite parasites interact with each other has changed over the past century. Bayer-Wilfert explained that the change is due to a combination of increased man-made movement of bee colonies over large geographic scales, and the emergence of Varroa mites as a carrier of DWV, which humans facilitated. "Moving animals and plants around, especially to areas where they are not native, can facilitate the spread of diseases," she explained.
The normal flight range of a bee hive's population is just over 6 miles, but because humans move whole hives over long distances, Varroa mites were able to spread from Southeast Asia through much of Russia within little more than a decade. "Some of the early spread can be traced back to efforts to increase beekeeping as part of developmental aid, largely a noble undertaking that did, however, contribute to the very rapid global spread of Varroa," Bayer-Wilfert said. She continued, "Honeybee queens, hives and bee products, such as pollen that can be used to supplement bees when local forage is poor, are also traded. In some cases, most notably pollen, we have only in recent years become aware of how easily these can spread diseases."
DWV does not just infect honeybees. It can infect bumblebees and other pollinators too, according to the researchers. Future studies will look at the role mites may play in infecting wild and unmanaged pollinators, like bumblebees. The good news is that the virus does not sicken humans. Varroa mites also do not parasitize people.
Symptoms of the virus include damaged wings and other bee body parts, miscoloring and paralysis of the legs and wings, and a severely reduced lifespan. Infected bees, such as this one, are typically expelled from the hive.
Winter, with its cooler weather and reduced food sources for bees, is especially tough for DWV victims. Since the mites are so plentiful and the virus spreads easily, many bees within a hive can be infected at once. "That means that whole honeybee hives may be lost over the winter period," Bayer-Wilfert said. To combat the problem, she and her colleagues call for upholding existing restrictions of the international movement of honeybees. Efforts should also be made to ensure that areas that are free from Varroa mites remain that way. "This is particularly relevant for smaller islands that may not have been a priority so far," Bayer-Wilfert said. "The best way of achieving this is to make the local beekeeping community aware of the potential risks." She added that there are several chemical treatments to rid bees of mites, but the mites have started to develop resistance against them. A non-chemical way of combating the mites, she says, is to cultivate a comb of male drone bee larvae (male larvae are larger and a better food source for the mites). Then that comb can be removed -- along with the mites -- from the colony. "This means that some larvae have to be sacrificed, but there is not chemical exposure of the rest of the hive and the mites cannot develop resistance," she said.
"Honeybees are our most important managed pollinator, but they face major threats across much of the globe," Mark Brown, a professor at Royal Holloway, University of London, told Discovery News. Brown is also the head of the university's Center for Ecology, Evolution and Behavior. "Understanding how deformed wing virus, which has a major impact on honeybee health, has spread around the world is important," he added. "It can help us to manage the future flow of honeybees and associated products to minimize the impact of emerging diseases like DWV, and to prevent the spread of future viruses." "Lena's results show clearly how DWV has spread, and thus give us clues as to where efforts could be best spent to protect the health of our managed honeybees, and the wild bees with which they interact."