{"id":18553,"date":"2012-04-16T12:00:54","date_gmt":"2012-04-16T11:00:54","guid":{"rendered":"http:\/\/www.transcend.org\/tms\/?p=18553"},"modified":"2012-04-11T00:25:21","modified_gmt":"2012-04-10T23:25:21","slug":"controversy-deepens-over-pesticides-and-bee-collapse","status":"publish","type":"post","link":"https:\/\/www.transcend.org\/tms\/2012\/04\/controversy-deepens-over-pesticides-and-bee-collapse\/","title":{"rendered":"Controversy Deepens Over Pesticides and Bee Collapse"},"content":{"rendered":"

A controversial new study of honeybee deaths has deepened a bitter dispute over whether the developed world\u2019s most popular pesticides are causing an ecological catastrophe.<\/em><\/p>\n

Researchers led by biologist Chensheng Lu of Harvard University report a direct link between hive health and dietary exposure to imidacloprid, a so-called neonicotinoid pesticide linked to colony collapse disorder<\/a>, the mysterious and massive die-off of bees across North America and Europe.<\/p>\n

The study isn\u2019t without critics, who say doses used in the study may be unrealistically high. But the level of a realistic dose is also a matter of controversy, and even critics say the findings are troubling.<\/p>\n

\u201cOur result replicates colony collapse disorder as a result of pesticide exposures,\u201d said Lu, who specializes in environmental exposures to pesticides. \u201cWe need to look at our agriculture policy and see if what we\u2019re doing now is sustainable.\u201d<\/p>\n

Developed in the 1990s as a relatively less-toxic alternative to pesticides that seriously harmed human health, neonicotinoids soon became the world\u2019s fastest-growing pesticide class and an integral part of industrial agricultural strategy. In the United States alone, neonicotinoid-treated corn now covers a total area slightly smaller than the state of Montana.<\/p>\n

Like earlier pesticides, neonicotinoids disrupt insects\u2019 central nervous systems. But unlike earlier pesticides, which affected insects during and immediately after spraying, neonicotinoids spread through the vascular tissues of plants. They\u2019re toxic through entire growing seasons, including flowering times when bees consume their pollen.<\/p>\n

The first reports of colony collapse disorder came in the mid-2000s from commercial beekeepers, who depending on region have experienced colony losses ranging from 30 to 90 percent. Commercial pollination costs have since skyrocketed<\/a>, and as wild bees are also afflicted<\/a>, even naturally occurring pollination is threatened.<\/p>\n

Measuring bee declines, however, proved much easier than explaining them. Among a lineup of potential culprits including fungus, mites, viruses, bacteria and pesticides, studies failed to find an obvious, smoking-gun cause \u2014 but, piece by piece, evidence against neonicotinoids has steadily accumulated.<\/p>\n

Honeybees are clearly exposed to them throughout the year and through multiple environmental routes<\/a>. At certain times, especially in spring, death often follows exposure, and even non-lethal exposures may disrupt bee learning and navigation<\/a>. Neonicotinoids also appear to make bees especially vulnerable to certain parasites<\/a> and may interact similarly with other stressors.<\/p>\n

Some European countries, including France, Germany and Italy, have even banned neonicotinoids, though pesticide companies vehemently defend their ecological safety and say concerns are based on inconclusive and premature science.<\/p>\n

Lu\u2019s study, released April 5 and scheduled for publication in the June Bulletin of Insectology<\/em>, attempts to replicate the life history of commercial bees, which are often fed dietary supplements of high-fructose corn syrup that may contain neonicotinoid residues that survive processing.<\/p>\n

\u201cWe tried to mimic commercial beekeepers\u2019 practices. I believe one reason that commercial beekeepers are experiencing the most severe colony collapse disorder is because of the link between high-fructose corn syrup and neonicotinoids,\u201d Lu said.<\/p>\n

In the spring of 2010, the researchers set up four groups of commercially purchased colonies. Each contained five hives, and during the summer months were fed a diet containing either no imidacloprid, what Lu considered a small dose of 20 parts per billion, or a much higher dose of 400 parts per billion.<\/p>\n

Colony collapse disorder is characterized in part by bees abandoning their hives during winter, and that\u2019s precisely what Lu\u2019s team reported in 15 of 16 imidacloprid-receiving hives. While other colony collapse disorder symptoms, such as queens that stay in the hive while workers flee, were not reported, Lu considers the experimentally induced collapse to be realistic.<\/p>\n

Reaction to the study was swift and varied.<\/p>\n

Bayer, the chemical and pharmaceutical giant that manufactures imidacloprid, issued a formal statement<\/a> denouncing the findings as \u201cspectacularly incorrect\u201d and \u201cbased on artificial and unrealistic study parameters that are wildly inconsistent with actual field conditions insecticide use.\u201d<\/p>\n

But Jeffery Pettis, a bee biologist at the United States Department of Agriculture, called the results \u201ctantalizing but not conclusive.\u201d With only four colonies used per dose level, the study\u2019s statistical significance is limited, \u201cbut I would love to see this study replicated\u00a0such that the trends \u2026 they observed could be actually validated,\u201d wrote Pettis in an email.<\/p>\n

Among Bayer\u2019s criticisms is that imidacloprid, a first-generation neonicotinoid, is little-used in the United States. It\u2019s largely been replaced by newer formulations \u2014 but these, said pesticide expert Charles Benbrook of The Organic Center, an organic food research consultancy<\/a>, are chemically similar to imidacloprid.<\/p>\n

\u201cVirtually all our corn seed has been treated with a very similar neonicotinoid,\u201d said Benbrook. If the study had been conducted with clothianidin, another controversial neonicotinoid, \u201cthey\u2019d almost certainly have found the same thing.\u201d<\/p>\n

According to Bayer, \u201canalysis from actual field grown corn samples have shown no detectable imidacloprid residues\u201d in high-fructose corn syrup. But Benbrook said that extensive testing by the Organic Center found traces of imidacloprid, but they were impossible to quantify.<\/p>\n

\u201cIt\u2019s very difficult to test for this particular chemical in high-fructose corn syrup. A lot of labs have spent lots of time trying to do it, but high-fructose corn syrup is a very sticky, dense matrix that basically gums up the testing machines<\/a>,\u201d said Benbrook. \u201cThat\u2019s why relatively little is known about imidacloprid in high-fructose corn syrup.\u201d<\/p>\n

Separate from the corn syrup issue is how the experiment\u2019s imidacloprid doses compared to real-world neonicotinoid exposures from pollen and crop residues. Bee biologist Dave Goulson of Scotland\u2019s University of Stirling, co-author of a recent paper on neonicotinoids and hive health<\/a>, said the doses \u201cseem to be unrealistically high,\u201d a critique echoed by Bayer.<\/p>\n

But Pettis said the study\u2019s lower dose ranges, which were sufficient to destroy the colonies, \u201cwere what bees could encounter in the environment.\u201d His take was echoed by biologist Christian Krupke of Purdue University, who said the doses \u201care certainly within the range that bees may encounter in the field.\u201d<\/p>\n

One way in which bees are regularly exposed to neonicotinoids is through drops of sap that form on the edge of plants<\/a>. Studies of these droplets have found neonicotinoid levels even higher<\/a> than those used in the new study, and the droplets can be fatal to bees (see video above).<\/p>\n

Another major route of exposure is through dust emitted by air-powered seed planters. Several years before the emergence of colony collapse disorder, neonicotinoid manufacturers started to coat seeds in the pesticides, vastly increasing the amount used in fields. The coatings are partially pulverized inside seed planters and emitted in plumes that appear to be highly toxic<\/a>. Neonicotinoids also remain biologically active in soil for years and perhaps decades, and it\u2019s possible that they seep into roots and throughout plants in ways that haven\u2019t yet been measured, said Krupke.<\/p>\n

The Environmental Protection Agency is currently evaluating the safety of neonicotinoids, and more than 1.25 million people have signed petitions requesting a ban. In parts of Europe that have already banned neonicotinoids, colony collapse disorder may have slowed<\/a>, though Krupke said these reports are too anecdotal to consider scientifically reliable.<\/p>\n

\u201cIf the relationship was as easy as that, we\u2019d have noticed it long ago. There are areas where neonicotinoids are used, but you don\u2019t have colony loss,\u201d Krupke said. \u201cBut what these studies are showing is that because neonicotinoids are absolutely ubiquitous, and we\u2019re seeing sub-lethal effects, is that they\u2019re stressors. They\u2019ve softened up the bees for other parasites.\u201d<\/p>\n

Pesticide risk analysis in the United States has focused too much on whether chemicals are immediately, obviously toxic, said Krupke. \u201cOur way of thinking is fundamentally flawed,\u201d he said. \u201cWe need to look at sub-lethal effects, and for a longer time period. These pesticides are everywhere, every year. We\u2019ve never used pesticides in the way we\u2019re using them now, where we charge up a plant and it expresses pesticides all year long.\u201d<\/p>\n

Lu described standing in front of the dosed beehives used in his experiment, and referenced Silent Spring<\/em><\/a>, an influential work that lamented the unintended consequences of bird-killing pesticides.<\/p>\n

\u201cThe hives were dead silent,\u201d he said. \u201cI kind of ask myself: Is this the repeat of Silent Spring<\/em>? What else do we need to prove that it\u2019s the pesticides causing colony collapse disorder?\u201d<\/p>\n

_____________________<\/p>\n

Brandon Keim – <\/strong><\/em>As a freelance science journalist, I\u2019m interested in those spaces where science, culture, history and nature converge. My work has appeared in Adbusters, Wired.com, the Christian Science Monitor, USA Today, ABC News, Seed, Psychology Today and Nature Medicine. I\u2019ve made broadcast appearances on NPR\u2019s Science Friday, Talk of the Nation and Here & Now, BBC\u2019s World Have Your Say, CBC\u2019s As It Happens, Animal Planet and G4\u2019s Attack of the Show. <\/em><\/p>\n

Go to Original \u2013 wired.com<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"

Researchers led by biologist Chensheng Lu of Harvard University report a direct link between hive health and dietary exposure to imidacloprid, a so-called neonicotinoid pesticide linked to colony collapse disorder, the mysterious and massive die-off of bees across North America and Europe.<\/p>\n","protected":false},"author":4,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[61],"tags":[],"class_list":["post-18553","post","type-post","status-publish","format-standard","hentry","category-environment"],"_links":{"self":[{"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/posts\/18553","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/comments?post=18553"}],"version-history":[{"count":0,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/posts\/18553\/revisions"}],"wp:attachment":[{"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/media?parent=18553"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/categories?post=18553"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.transcend.org\/tms\/wp-json\/wp\/v2\/tags?post=18553"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}