May 18, 2009
Pesticides indicted in bee deaths
http://www.salon.com/env/feature/2009/05/18/bees_pesticides/
Agriculture officials have renewed their scrutiny of the world's best-selling pest-killer as they try to solve the mysterious collapse of the nation's hives.
【生物】消えたミツバチ
http://www.worldwatch-japan.org/NEWS/worldwatchreport09040601.htm
アメリカの新聞には、２年近くにわたり不吉な見出しが躍っている。不可解な病気、蜂群崩壊症候群（CCD）を伝える記事だ。CCDが原因で多くの作物 の受粉を助けるミツバチが壊滅状態にある。ミツバチが消えれば、田畑は不毛の地となり、経済が崩壊し、食料不足に陥るだろうと記事は続いている。 アメリカでは、アーモンドからズッキーニに至るまで100以上の農作物の商業的生産がミツバチの媒介に依存していると言われている。多くの生産者は、商業 養蜂家から、ミツバチを借りる。養蜂家は、ミツバチの巣箱を場所から場所に移動させ、さまざまな農作物を受粉させるのである。花粉媒介産業の最大規模の例 として、カリフォルニアのアーモンド畑があげられる。毎年２月中旬から３月中旬にかけて600億匹近いミツバチを集め、22万3000ヘクタールに広がる アーモンドの花を受粉させる。
たったひとつの外来種のハチで成り立っている花粉媒介産業が、どのようにして、かつては多様な野生種のハチが提供していた無料の花粉媒介サービスに取って 代わってしまったのか、正確にはわかっていない。しかし、生態学者の間では、花粉媒介産業と農業集約化に密接な関連があるということでほぼ意見が一致している。アメリカで花粉媒介産業が生まれたのは、20世紀中ごろ、農場主が大量の有機リン酸エステル系農薬の使用を始め、大規模な単一栽培農業を導入し、農場の周囲や道路わきから野生植物を一掃する「除草農法」を採用した時期である。蜂群崩壊症候群（CCD:Colony Collapse Disorder）は不思議な現象である。最初に報告されたのが2006年秋で、数人の養蜂家が、ミツバチが巣箱からすっかり消えているのを発見し た。死んだハチより逃げたハチの方が多かった。通常は必死に巣箱を守るハチが（だからこそハチは刺すのだが）、女王バチや生まれて間もないハチを置き去り にして逃げてしまったのだ。
科学者が確認しているのは、CCDが劇的かつ広範な問題であるということだ。CCDが発生した最初の冬にあたる、2006年から2007年にかけて、 CCDの被害を受けたアメリカの養蜂家は、全養蜂家の１／４に及んだ。巣箱のミツバチの30〜90％が忽然と消えたのだ。翌年は冬の気候が温暖であったた め、弱体化したハチ群には救いであったが、それでも全米のハチの消失数は、その前年よりも若干増加した。CCDは、全米36の州で報告されている。カナ ダ、一部のヨーロッパ諸国、インド、台湾、ブラジルのハチもその影響が疑われている。2009/4/ 5 ミツバチはどこへ消えた？ 受粉進まず農家に大打撃
http://www.j-cast.com/2009/04/05038846.htmlミツバチが日本から姿を消している。農薬による死滅や寄生虫の大発生などの要因が重なったからだという。そのせいで、交配用のミツバチが不足し、ミツバチを必要とするイチゴやメロン、スイカを栽培する農家は頭をかかえている。
2008年夏頃から、ミツバチが大量に死滅
ミツバチの数が減っている交配用のミツバチの販売を手がける、丸東東海商事（愛知県豊橋市）の代表、金子幸義さんは「ミツバチの出荷量が業界内では前年比で50％減った」と話す。2008年夏頃から突如として、ミツバチが減ったからだ。
原因は3つある。1つめは、主に水田で使われる害虫駆除を目的とした農薬「ネオニコチノイド」による死滅だ。主に北海道・東北地方でこうした 事態が起きた。2つめは、ミツバチに寄生する「ヘギイタダニ」が大発生したこと。駆除する薬が効きにくくなっていたこともあり、ミツバチが死に絶えてし まった。3つめは、女王蜂の輸入ができないこと。女王蜂は海外で伝染病が確認され、2008年11月から輸入できない状況が続いている。これにより、ハチの数が減ってしまったというわけだ。
ちなみに、ミツバチが大量に姿を消してしまう「蜂群崩壊症候群（CCD:Colony Collapse Disorder）」と呼ばれる謎の現象もある。アメリカでは一昨年から去年にかけて、 全米のミツバチ3分の1以上が消えたといわれ、関係者を悩ませている。しかも、原因は全くわからず、今後、日本でも同様の事態が起きる可能性も心配されて いる。
「不受精でイチゴが実らない、小さい」
ミツバチ減少により、ミツバチ不足の状況が続いている。ミツバチを使って受粉させるイチゴやメロン、スイカなどを栽培する農家では、ミツバチの仕入れが前年より少ないようだ。
ミツバチ不足のせいで、販売価格も高騰している。丸東東海商事では、およそ10アールの広さで使えるミツバチ6000匹の価格は現在、2万6000円。前年同期比1万円程度の値上げだという。
もっとも、前出の金子さんによると、3、4月はミツバチの繁殖期であることから、ミツバチが増えている状況にはある。あたたかい地域を中心に 繁殖を急いでおり、「4月は前年比で80％近くまでは戻るのでは」と見込んでいる。だが、ミツバチが不足していることに変わりはなく、高価格の状況はしば らく続きそうだ、という。
とはいえ、ミツバチ不足で最も打撃を受けるのは農家だ。栃木県にある養蜂園の担当者は、イチゴ農家から寄せられた話を交えて、こう話す。
「農家の方からは今年、不受精でイチゴが実らなかったり、小さかったり、形が悪かったりすると聞いています。これは、昨年までは ほとんど無かったので、やはりミツバチが少なかったことが影響しているようです。イチゴの出荷時期は5月。農家の間では売り上げが2割近く落ちるのでは、 と嘆いています」
原因は「疫病説」（イスラエル急性麻痺ウィルス (Israeli acute paralysis virus）、「栄養失調説」、「ネオニコチノイドやイミダクロプリドなどの殺虫剤説」、「電磁波説」「害虫予防のための遺伝子組み換え農作物説」（3倍体トウモロコシ等）、「ミツバチへの過労働・環境の変化によるストレス説」などが唱えられているが、未だ解明はされていない。 CCDは、問題の発生した地域の商業養蜂家により報告されており、野生のコロニーや有機養蜂では発生していない。そのため、養蜂の慣習が基本的な要素であると考えられている。
Gene Brandi will always rue the summer of 2007. That's when the California beekeeper rented half his honeybees, or 1,000 hives, to a watermelon farmer in the San Joaquin Valley at pollination time. The following winter, 50 percent of Brandi's bees were dead. "They pretty much disappeared," says Brandi, who's been keeping bees for 35 years.
Since the advent in 2006 of colony collapse disorder, the mysterious ailment that continues to decimate hives across the country, Brandi has grown accustomed to seeing up to 40 percent of his bees vanish each year, simply leave the hive in search of food and never come back. But this was different. Instead of losing bees from all his colonies, Brandi watched the ones that skipped watermelon duty continue to thrive.
Brandi discovered the watermelon farmer had irrigated his plants with imidacloprid, the world's best-selling insecticide created by Bayer CropScience Inc., one of the world's leading producers of pesticides and genetically modified vegetable seeds, with annual sales of $8.6 billion. Blended with water and applied to the soil, imidacloprid creates a moist mixture the bees likely drank from on a hot day.
日本のバイエル クロップサイエンスの結城中央研究所は、世界No.1殺虫剤「アドマイヤー」の有効成分イミダクロプリド：１−（６−クロロ−３−ピリジルメチル）−Ｎ−ニトロイミダゾリジン−２−イリデンアミン：を開発するなど、日本だけでなくグローバ ルでも事業の牽引役となっています。
Stories like Brandi's have become so common that the National Honeybee Advisory Board, which represents the two biggest beekeeper associations in the U.S., recently asked the U.S. Environmental Protection Agency to ban the product. "We believe imidacloprid kills bees -- specifically, that it causes bee colonies to collapse," says Clint Walker, co-chairman of the board.
Beekeepers have singled out imidacloprid and its chemical cousin clothianidinクロチアニジン, also produced by Bayer CropScience, as a cause of bee die-offs around the world for over a decade. More recently, the same products have been blamed by American beekeepers, who claim the product is a cause of colony collapse disorder, which has cost many commercial U.S. beekeepers at least a third of their bees since 2006, and threatens the reliability of the world's food supply.
クロチアニジンは、武田薬品工業（住化武田農薬→住友化学が吸収合併）が開発したチアゾール環を有するネオニコチノイド系殺虫剤。幅広い害虫に低薬量で効果を発揮し、作物に対しても安全性の高い化合物とされている。
海外では、韓国、台湾、米国、欧州、東欧など20カ国以上で登録済である。主としてバイエルクロップ サイエンス 社と共同で海外展開している。
Scientists have started to turn their attention to both products, which are receiving new scrutiny in the U.S., due to a disclosure in December 2007 by Bayer CropScience itself. Bayer scientists found imidacloprid in the nectar and pollen of flowering trees and shrubs at concentrations high enough to kill a honeybee in minutes. The disclosure recently set in motion product reviews by the California Department of Pesticide Regulation and the EPA. The tests are scheduled to wrap up in 2014, though environmentalists, including the Sierra Club, are petitioning the EPA to speed up the work.
For over a decade, Bayer CropScience has been forced to defend the family of insecticides against calls for a ban by beekeepers and environmentalists. French beekeepers succeeded in having imidacloprid banned for use on several crops after a third of the country's bees died following its use in 1999 -- although the French bee population never quite rebounded, as Bayer is quick to point out. Germany banned the use of clothianidin and seven other insecticides in 2008 after tests implicated them in killing up to 60 percent of honeybees in southwest Germany.
Imidacloprid and clothianidin are chloronicotinoids, a synthetic compound that combines nicotine, a powerful toxin, with chlorine to attack an insect's nervous system. The chemical is applied to the seed of a plant, added to soil, or sprayed on a crop and spreads to every corner of the plant's tissue, killing the pests that feed on it.
Pennsylvania beekeeper John Macdonald has been keeping bees for over 30 years and recently became convinced that imidacloprid is linked to colony collapse disorder. It's the only explanation he can find for why his bees, whose hives border farmland that uses the pesticide, started dropping dead a few years ago.
"There's the pernicious toxic effect -- it does everything nicotine does to our nervous system," says Macdonald. "There's the pathological effect, the interference with basic functions. They get lost, they get disoriented. They fall to the ground. They get paralyzed and their wings stick out. I can't think of anything in the environment that's changed other than farming, and virtually every farmer is using treated seeds now."
Bayer CropScience spokesman Jack Boyne says his company's pesticides are not to blame. "We do a lot of research on our products and we feel like we have a very good body of evidence to suggest that pesticides, including insecticides, are not the cause of colony collapse disorder," he says. "Pesticides have been around for a lot of years now and honeybee collapse has only been a factor for the last few years." (Imidacloprid has been approved for use in the U.S. since 1994 and clothianidin has been used since 2003.)
Scientists continue to investigate the causes of colony collapse disorder. Leading theories suggest a combination of factors that include parasitic mites, disease, malnutrition and environmental contaminants like pesticides, insecticides and fungicides. The current EPA review will provide further insight into the role of pesticides, as it will uncover whether honeybees sickened by exposure to imidacloprid spread it around by bringing contaminated nectar and pollen back to the hive.
EPA critics suggest that the agency allowed economic considerations to take precedence over the well-being of honeybees when it approved imidacloprid for sale in the U.S. 15 years ago. "I think the EPA and USDA [U.S. Department of Agriculture] have been covering up for Bayer, and now they're scrambling to do something about it," says Neil Carman, a plant biologist who advises the Sierra Club on pesticides and other issues. "This review should have been done 10 years ago. It's been found to be more persistent in the environment than was reported by Bayer."
Imidacloprid was approved with knowledge that the product, marketed as Gaucho, Confidor, Admire and others, was lethal to honeybees under certain circumstances. Today the EPA's own literature calls it "very highly toxic" to honeybees and other beneficial insects. Its workaround was to slap a label on the product, warning farmers not to spray it on a plant when bees were foraging in the neighborhood.
In its 2007 studies, Bayer applied standard doses of imidacloprid to test trees, including apple, lime and dogwood. Its scientists found imidacloprid in nectar at concentrations of up to 4,000 parts per billion, a dose high enough to kill several bees at once. (Honeybees can withstand a dose of up to 185 ppb, the standard amount it would take to kill 50 percent of a test population.) What caught the attention of California agricultural officials was that the test trees contained the same amount of deadly imidacloprid as the citrus and almond groves regularly sprayed by farmers, and pollinated by bees. (California's almond industry has increased its use of imidacloprid by a factor of 300 in the past five years.) Agricultural officials were also surprised to learn that the imidacloprid can persist in the leaves and blossoms of a plant for more than a year.
The Bayer results don't surprise University of California at Davis professor Eric Mussen, a well-known entomologist and one of the country's leading experts on colony collapse disorder. Mussen has seen a variety of unpublished studies with similar results, including one at U.C. Riverside that found imidacloprid in the nectar of a eucalyptus tree bloom at concentrations of 550 ppb a full year after it was applied.
"From some of the data on the trees, it appears as though there are situations where honeybees can get into truly toxic doses of the material," says Mussen, who avoids spraying imidacloprid on his own demonstration fields at U.C. Davis. "This the first time that we've had something you put in a tree that could stay there for a long time."
But Mussen isn't convinced imidacloprid is a primary cause of the honeybee die-off. He explains that some bees settle on fields of sunflowers and canola treated with the chemical and then "fly right through to next year." So imidacloprid is not the only story. "Could it be part of the story?" he asks. "I'm sure. I think any of the pesticides the bees bring back to the beehive is hurting the bees."
Mussen adds that ongoing research into chronic exposure to insecticides will be crucial. It's likely, he says, that exposure to even low doses acts like a one-two punch: It can weaken the bees until a parasite or pathogen moves in to finish them off.
As the EPA begins its pesticide studies this year, skeptics wonder whether the agency can conduct an unbiased review. Back in 2003, they point out, the EPA reported that clothianidin was "highly toxic to honeybees on an acute contact basis," and suggested that chronic exposure could lead to effects on the larvae and reproductive effects on the queen. Although the EPA asked Bayer for further studies of its effects on honeybees, it nevertheless authorized the chemical for market.
"If the EPA had sufficient concern about harm to bees that they would insist on other studies, it seemed unwise to approve it anyway and ask for research after the fact," says Aaron Colangelo, an attorney with the Natural Resources Defense Council. "The EPA's job is to make a decision about whether a chemical is safe or not."
Colangelo envisions a similar scenario in coming years. The EPA has announced it will review clothianidin and other chemicals in the same family, but not until 2012. In the meantime, there's nothing stopping the agency from approving the insecticides for use on new crops based on existing policies. In the end, Colangelo has little confidence the federal agency will bring a hammer down on the agribusiness giant. The EPA, he explains, often keeps its test results confidential for proprietary reasons at a company's request. As a consequence, it's unclear where gaps or discrepancies occur until a company makes a disclosure similar to Bayer's.
"They're not making decisions about whether the pesticide can be put on the market based on impacts to bees, no matter how much evidence of harm there is," Colangelo says. "The EPA will just approve it anyway and put a warning label on the product."
Halting the sale of pesticides, though, would be no mean task. Over 120 countries use imidacloprid under the Bayer label on more than 140 crop varieties, as well as on termites, flea collars and home garden landscaping. And the product's patent expired a few years ago, paving the way for it to be sold as a generic insecticide by dozens of smaller corporations. In California alone, imidacloprid is the central ingredient in 247 separate products sold by 50 different companies.
In a statement, the EPA says that before banning a pesticide, it "must find that an 'imminent hazard' exists. The federal courts have ruled that to make this finding, EPA must conclude, among other things, that there is a substantial likelihood that imminent, serious harm will be experienced from use of the pesticide." The EPA did not clarify what is meant by "imminent hazard" and why the death of honeybees does not qualify.
As Mussen points out, though, a few million dead honeybees may be the cost of doing business. "If they didn't register products that were toxic to honeybees, there wouldn't be a lot of products on the market that were available for pest control."
All the more reason to start taking the world's most ubiquitous insecticide off the market and invent a safer one, argues Walker, of the National Honeybee Advisory Board. "It's on every golf course, it's on every lawn. It's not just an agricultural product. There's really not one part of our lives it's not touching."