Honeybee die-off threatens crops in US and Europe

Scientists and apiarists are scrambling to explain the mysterious and unprecedented disappearance of bees that began affecting the US and Europe in the last months of 2006. As many as 700,000 of the US' 2.4 million bee colonies have been affected, according to the American Beekeeping Federation. The West Coast is thought to have lost 60 percent of its commercial bee population, with 70 percent missing on the East Coast. In London, about 4,000 hives–two-thirds of the bee colonies there–are estimated to have died this winter. In Spain, thousands of colonies are said to have been lost, and up to 40 percent of Swiss bees are reported to have disappeared or died. Heavy losses have also been reported in Poland, Croatia, Portugal, Italy and Greece. "It's called Colony Collapse Disorder (CCD)," said Jerry Bromenshenk, a University of Montana professor and head of Bee Alert Technology Inc. "We don't know that it's a disease, we don't know if it's due to management practices by beekeepers. There are so many variables. We can't yet find a common denominator." Crucial pollinators A recent report by the National Research Council noted that in order to bear fruit, three-quarters of all flowering plants–including most food crops and some that provide fiber, drugs and fuel–rely on pollinators for fertilization. Honeybees have been around for at least 150 million years, but in the past half-century, nearly all the wild bees have disappeared, the result of a combination of disease and loss of habitat. Because of this, beekeeper services are vital for the pollination of food crops. One-hundred and forty billion commercially raised honeybees are responsible for pollinating about $20 billion worth of crops, according to US Department of Agriculture (USDA) statistics. Search for clues A working group of university faculty researchers, state regulatory officials, and industry experts are working to identify the cause or causes of CCD and to develop recommendations for beekeepers. Organizations participating in the CCD Working Group include Penn State, the USDA, the agriculture departments in Pennsylvania and Florida, and Bee Alert Technology Inc., a technology transfer company affiliated with the University of Montana. "Unfortunately, beekeepers have struggled over the last few years from colonies dying from introduced parasitic mites and other things," says Jerry Hayes, the president of the Apiary Inspectors of America and member of the CCD Working Group. "They're already kind of numb because of all the problems. But last summer, beekeepers began losing colonies for reasons that weren't quite in line with the other problems." Over the course of a few weeks, beekeepers noticed colony bee numbers would dwindle as the insects simply disappeared. "With affected hives, there are no dead or dying bees on the ground as we see with pesticide exposures or other diseases. No one can explain this behavior," says Hayes. The scientists are also surprised that bees and other insects usually leave the abandoned hives untouched. Nearby bee populations or parasites would normally raid the honey and pollen stores of colonies that have died. "This suggests that there is something toxic in the colony itself which is repelling them," says Diana Cox-Foster, Penn State entomology professor and member of the CCD Working Group. "We've had reports of beekeepers forced out of business," reports Hayes. "They can't fulfill pollination contracts. Other businesses that normally provide queen bees are canceling orders. They don't have enough bees to work with." At some point, warns Hayes, "the lines on the graph will cross and there won't be enough honeybees in the United States to pollinate our crops." Cox-Foster says that researchers are "extremely alarmed," adding that the crisis "has the potential to devastate the US beekeeping industry." "Preliminary work has identified several likely factors that could be causing or contributing to CCD," says Dennis vanEngelsdorp, acting state apiarist with the Pennsylvania Department of Agriculture and member of the Working Group. "Among them are mites and associated diseases, some unknown pathogenic disease and pesticide contamination or poisoning." "They're looking for things affected beekeepers don't have in common–they can assume those aren't the cause," says Ed Levi, of the Arkansas State Plant Board. "Then, of course, they're looking at what the affected operations do have in common. "Taking all that information, they've narrowed down the possibilities. That doesn't mean the nail has been hit on the head. But all the possibilities concern stresses on the bees of some sort." Collapsed colonies generally contain only a queen, a few attendants, eggs and brood (baby bees). Often the few bees left behind appear to suffer from an immune system collapse. The bees seem to be susceptible to bacteria and fungi that normally would cause no harm. "That, too, is highly unusual, and we've been trying to find the cause for several months. It seems to indicate some sort of mass immune deficiency." says Hayes. In many cases, scientists have found evidence of almost all known bee viruses in the few surviving bees found in the hives after most have disappeared. Some had five or six infections at the same time and were infested with fungi–a sign, experts say, that the insects' immune system may have collapsed. Pesticides and GMOs Normally, honeybees forage within a 2.5-mile radius of their colony. "Of course, honeybees are exposed to agricultural chemicals sprayed on crops or used systemically to control pests," says Hayes. "Those pests are mostly insects, but so are honeybees. Even at sub-lethal levels, some of the chemicals can find their way through plant nectar and pollen to the bees." says Hayes. Jean-Claude Tassot, a beekeeper from Morris County, NJ said, "We have suspicions about pesticides. We noticed most of the dead hives are close to cornfields... And when we asked other beekeepers what was the principle crop near their hives, they said corn, corn, corn." One commonly used pesticide is a neurotoxin called imidacloprid, which works by blocking a pathway in insect brains that results in an accumulation of a neurotransmitter which leads to paralysis and death. At sublethal doses, imidacloprid may affect honeybees' ability to navigate. In a 2001 article in the Journal of Pesticide Reform, German scientist Eric Zeisstoff wrote that his research "indicated that bees affected by imidacloprid suffer problems with orientation. Bees with a particular level of imidacloprid contamination at [.31 miles] from the colony did not return to the hive at all." Genetically Modified Organisms (GMO) have also been implicated in the die-off. "There are some concerns about GMO crops that can produce a toxin used to battle harmful insects. Those traits are also in nectar and pollen," says Hayes. The most commonly transplanted segment of transgenic DNA involves genes from a well-known bacterium, bacillus thuringiensis (Bt), which has been used for decades by farmers and gardeners to control insects. Instead of the bacterial solution being sprayed on the plant the genes that contain the insecticidal traits are incorporated into the genome of the farm crop. As the transformed plant grows, these Bt genes are replicated along with the plant genes so that each cell contains its own poison pill that kills the target insect. Walter Haefeker, vice president of the European Professional Beekeepers Association who also sits on the board of directors of the German Beekeepers Association, recently sent a researcher at the CCD Working Group some data from a bee study that he has long felt shows a possible connection between genetic engineering and diseases in bees. The study concluded that there was no evidence of a "toxic effect of Bt corn on healthy honeybee populations." But when, by sheer chance, the bees used in the experiments were infested with a parasite, something eerie happened. A "significantly stronger decline in the number of bees" occurred among the insects that had been fed a highly concentrated Bt poison feed. According to Hans-Hinrich Kaatz, the director of the study, the bacterial toxin in the genetically modified corn may have "altered the surface of the bee's intestines, sufficiently weakening the bees to allow the parasites to gain entry–or perhaps it was the other way around. We don't know." The planting of transgenic corn and soybean has increased exponentially, according to statistics from farm states. Weather Some beekeepers are blaming a resurgent winter for taxing the honeybee population. Bee expert James Tew of Ohio State University's Honeybee Laboratory said the cold could contribute to a 40 to 70 percent death rate. The cold weather hit after a warm spell that allowed the bees to lay eggs, gather food and make wax. The cold snap meant the bees couldn't leave their hives to get food. Mobile phones On Apr. 14, UK' s Independent reported that, "a limited study... has found that bees refuse to return to their hives when mobile phones are placed nearby." However, the device used in this study was a base station for Digital Enhanced Cordless Telecommunications–essentially cordless phones. The radiation these emit is very different from that emitted by cellphone towers, and was at a much higher intensity than can be found in nature. Other stresses Other stress factors can play a role in the weakening of colonies. Many of the beekeepers experiencing this problem are "commercial and large," says Hayes. "Lots of them are migratory, moving their bees to different crops as they're needed. The bees seem to be stressed from either the migration or colony splits. Large beekeepers, especially, have a tendency to split colonies to make more. There's been stress from over-splitting." Jürgen Tautz, a bee researcher at the University of Würzburg in Germany believes that intensive beekeeping may itself be one of the main problems. Raising dense colonies of bees narrows the genetic pool for a population, and less genetic variation weakens any species. Research needed "Just when this phenomenon began is hard to pin down," says Bromenshenk, "because the reporting of problems is not organized." While the USDA keeps statistics on honey production, it does not track trends in pollination. "Unfortunately, historically, honeybee research hasn't gotten the kind of funding it deserves, considering the vital role honeybees play in agriculture," says Ed Levi of the Arkansas State Plant Board. "The universities and USDA labs working with bees are underfunded. That needs to change."