Bijen

Dass die Insekten auf dem Rückzug sind, ist vielen Menschen nicht bewusst. Eine Ausnahme bilden die Bienen. Ihr Niedergang ist bereits länger bekannt, was unter anderem daran liegt, dass sie als fleissige und nützliche Tiere gelten. Der Rest ist meistens nur lästig. Erst langsam spricht sich herum, dass auch Falter, Fliegen und Wespen bedroht sind.

Individually, insects are not incredibly interesting, unless you get down on the ground or view them under a microscope to look at their complexity. But they are the invisible force working throughout the world to keep it running. There are 1.4 billion insects for each one of us. Insects are “the lever pullers of the world,” says David MacNeal, author of Bugged. They do everything from feeding us to cleaning up waste to generating $57 billion for the U.S. economy alone. Almonds in California or watermelons in Florida wouldn’t be available if it were not for bees.

We tested the effects of acute or chronic exposure to thiamethoxam on the flight ability of foragers in flight mills. Within 1 h of consuming a single sublethal dose (1.34 ng/bee), foragers showed excitation and significantly increased flight duration (+78%) and distance (+72%). Chronic exposure significantly decreased flight duration (−54%), distance (−56%), and average velocity (−7%) after either one or two days of continuous exposure that resulted in bees ingesting field-relevant thiamethoxam doses of 1.96–2.90 ng/bee/day.

Neonicotinoids act as neurotoxins. Whether the interactions of imidacloprid with its target site in the nervous system – the nicotinic acetylcholine receptor - is reversible or not is an academic controversy which has practical implications for the risk assessment of neonicotinoids. Some scientists argue that imidacloprid irreversibly blocks the nicotinic acetylcholine receptors. Indeed, the lethality of imidacloprid to insects appears to be dependent on the time of exposure: the longer the exposure time, the less amount of total chemical is needed to kill honeybees.

Pollinators have a staunch ally in Graham White. White, a small-scale hobby beekeeper in Scotland, has been an international campaigner on the dangers of neonicotinoid pesticides since 2003. Born into a family of coal miners and glassmakers in an industrial town near Liverpool, England, White developed his love of nature exploring remnant woodlands and abandoned 19th century canals. He credits his 1976 expedition, hiking the John Muir Trail from Yosemite to Mt. Whitney in California, with changing his life.

Desde hace años los investigadores de todo el mundo intentan dar con la clave que produce la muerte de las abejas a escala global. Los estudios desarrollados durante varias décadas apuntan hacia distintos factores ambientales y el uso de pesticidas agrícolas como causas probables de la progresiva desaparición de estos insectos.Ahora, dos equipos de científicos del Reino Unido han llevado a cabo por primera vez una investigación a gran escala que demuestra los efectos negativos de los pesticidas derivados de la nicotina en diferentes especies de abejas.

Lo studio “Country-specific effects of neonicotinoid pesticides on honey bees and wild bees”, pubblicato su Science da un team di ricercatori britannici, tedeschi e ungheresi guidati da Ben Woodcock del Centre for ecology and hydrology (Ceh) del Natural environment research council (Nerc), espone i risultati di un esperimento sul campo su vasta scala per valutare gli impatti di pesticidi neonicotinoidi sulle api da miele e le api selvatiche in tutta Europa.

Ein aktueller Bericht des Bundes bestätigt, was unlängst befürchtet wird: Immer mehr Lebensräume, Pflanzen- und Tierarten sind bedroht. Über ein Drittel – weit mehr als in anderen europäischen Ländern – der beobachteten Pflanzen-, Tier- und Pilzarten werden aufgrund der Ergebnisse als bedroht eingestuft. Der häufige Einsatz von Pestiziden im Ackerbau ist verheerend für Insektenpopulationen. Auch in unserem Nachbarland sind die Bestände der Insekten im Sinkflug: In Deutschland ist mancherorts der Fluginsektenbestand seit 1989 um 80 Prozent geschrumpft (naturschutz.ch berichtete).