Compelling new evidence from the US government's top bee expert that modern pesticides may be a major cause of collapsing bee populations led to calls yesterday for the chemicals to be banned. A study published in the current issue of the German science journal Naturwissenschaften, reveals how bees given minute doses of the widely used pesticide imidacloprid became more vulnerable to infections from a deadly parasite, nosema. The study, led by Dr Jeffrey Pettis, the head of the US Department of Agriculture's Bee Research Laboratory, says: "We believe that subtle interactions between pesticides and pathogens, such as demonstrated here, could be a major contributor to increased mortality of honey bee colonies worldwide."
Source: The Independent, 29th January 2012
http://www.independent.co.uk/environment/nature/pesticides-blamed-for-b…
The decline of bees has been in the headlines for several years, and theories to explain their deaths abound. But perhaps there is not just one single cause. University of California San Diego professor of biology James Nieh studies foraging, communication and health of bees. "I would say it's a combination of four factors; pesticides, disease, parasites, and human mismanagement," says Nieh. Bees might be weakened by having a very low level of exposure to insecticides or fungicides, making them more susceptible if they are attacked by viruses or parasites. "It's kind of like taking a patient who is not doing so well -- very weak, poor diet, exposing them to pathogens, and then throwing more things at them. It's not surprising that honeybees are not very healthy." One class of pesticides, neonicotinoids in particular has received a lot of attention for harming bees. In late 2010, the EPA came under fire from beekeepers and pesticide watchdog organizations. This happened when Colorado beekeeper Tom Theobald spoke out about how the EPA allowed clothianidin to be used without any proof it was safe and despite the fact that the EPA's own scientists believed it "has the potential for toxic risk to honey bees, as well as other pollinators." At that time Theobald had reported losing up to 40 percent of his bees, and now, things are looking even worse. "As a business, I think it's over," he says. "I think my business is no longer viable. I'll continue to keep bees as best I can and may be able to pull off a halfway decent crop for another year or two but the trendline is down and over the edge of a cliff and that's typical of what's going on nationally." A recently published study sheds a little more light on the impact of clothianidin. The study, which focuses on pesticide exposure in bees, looks at two pesticides that are used by treating seeds prior to planting. Each corn seed contains enough pesticide to kill 80,000 honeybees. Once the plant develops, all parts of the plant -- including the pollen collected by bees -- contain lower doses of the pesticide. One of the main revelations of the study is that bees get a hefty dose of these pesticides, clothianidin and thiamethoxam, during spring planting as the seeds are coated in talc to keep them from sticking together and then much of the talc enters the environment either with the seed or behind the planter through its exhaust fan.
The study found the pesticides on the soil of fields -- even unplanted fields -- and on nearby weeds, as well as in dead honeybees and in pollen collected by honeybees. Clothianidin is used on both corn and canola in the U.S., and while corn does not rely on honeybees for pollination (it is wind pollinated), the study found that "maize pollen comprised over 50 percent of the pollen collected by bees, by volume, in 10 of 20 samples." Tucked in the middle of the study is a bombshell: "The levels of clothianidin in bee-collected pollen [from treated maize] that we found are approximately 10-fold higher than reported from experiments conducted in canola grown from clothianidin-treated seed." This is significant because the pesticide clothianidin was deemed safe to bees by the EPA following a study of bees exposed to treated canola, a minor crop in the United States. However, according to the study, the pesticide dose bees are exposed to in the U.S. is usually ten times that, as corn (maize) covers more than 137,000 square miles in the U.S. -- an area larger than the state of New Mexico. So even though bees aren't pollinating corn directly, they still may be getting a toxic dose of pesticides from it.
To beekeepers, the news is not terribly surprising. Beekeeper Dave Hackenberg says, "You talk to more and more beekeepers across the country that don't really understand what's going on that are losing bees in the spring of the year when nobody's really spraying. You ask if there's corn there, and yeah, there's corn everywhere." Hackenberg, a commercial beekeeper with 3,000 hives, somewhat unwittingly alerted the world to the mass deaths of bees after suffering major losses of his own bees in November 2006. "We were knocking our heads out trying to figure out what went wrong," he recalls. First he checked the hives for mites but found none. He called in experts from Penn State, who worked day and night, combing through the hives, and taking all kinds of samples. "Within four or five days they said 'We're finding stuff we've never seen before and you definitely don't have the virus we were looking for.' They saw paralysis in the bees, crystallization in their intestines, things that nobody had seen before, but nobody looked probably."
Several months later, Hackenberg's troubles were written up in the Philadelphia Inquirer. Within two days, his story appeared in 487 newspapers around the world. Hackenberg says that, for beekeepers, "Somebody changed the rules and forgot to tell us."
Source:
By Jill Richardson, the founder of the blog La Vida Locavore and a member of the Organic Consumers Association policy advisory board. She is the author of Recipe for America: Why Our Food System Is Broken and What We Can Do to Fix It..
AlterNet, February 12th, 2012
http://www.alternet.org/environment/154039/have_bees_become_canaries_in…
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