Insecticiden

Neonicotinoide sind Insektenvertilgungsmittel, die manche für Wunderwaffen auf dem Acker halten. Aber das Gift tötet nicht nur Schädlinge, sondern bedroht in Kleinstmengen auch Menschen. Die Pestizide wirken als Nervengift tödlich auf Insekten und bilden dauerhaft Rückstände in Pflanzen. Japanische Wissenschaftler haben in Versuchen nachgewiesen, dass Neonicotinoide verheerend auf die Gehirnentwicklung von Föten und Säuglingen wirken. Die Spurensuche nach den Neonicotinoiden führt "planet e." nach Japan. Dort hat Recherchen zufolge der Einsatz dieser Mittel mutmaßlich zahlreiche Menschen gesundheitlich geschädigt. Aber auch in Europa warnte die zuständige Behörde für Lebensmittelsicherheit EFSA schon vor zwei Jahren vor den Folgen des Pestizids, besonders für Babys und Kinder. Doch noch immer werden Neonicotinoide in Europa und auf der ganzen Welt tonnenweise ausgebracht. Gegen ein drohendes Totalverbot laufen jetzt die Hersteller und Lobbyisten Sturm: in Brüssel bei der EU und in Berlin bei den zuständigen Ministerien. "planet e." spricht mit Prof. Karl Zwiauer vom Universitätsklinikum St. Pölten in Niederösterreich. Der Kinderarzt rät Eltern vorsorglich vom Verzehr mit Neonicotinoiden behandelter Lebensmittel ab. Das Gift gelange über die Plazenta oder die Muttermilch unmittelbar zum Nachwuchs. Zwar sei ein direkter Nachweis oft schwierig. Doch Gifte wie die Neonicotinoide wirkten schleichend und es sei möglich, dass spätere Lern- und Kommunikationsschwierigkeiten darauf zurückzuführen sind. Dabei, erklärt Dr. Henk Tennekes in "planet e.", sei die Menge des aufgenommenen Pestizids unwichtig. Der Toxikologe hat nachgewiesen, dass Neonicotinoide im Gegensatz zu andern Pestiziden schon in kleinsten Mengen wirken. "Es gibt keine Schwelle, keinen Grenzwert, bei dem die Neonicotinoide nicht gefährlich sind", so Tennekes in der Dokumentation über die Neonicotinoide - die schleichende Gefahr vom Acker.

Bats get their own day on the last weekend of August. Or rather, night: on European Bat Night, an international event promoted by UN bats secretariat Eurobats looks to get people closer to these animals. This is hoped to help the public better understand the important role of bats in the ecosystem, and encourage their conservation - since many species are in danger of extinction. These winged mammals are a "keystone species" essential to some ecosystems, being responsible for the natural control of agricultural pests, pollination of plants and seed distribution. Bats are critical to the survival of many wild species. Without them, the diversity of plants and animals on Earth would be greatly reduced. Even their droppings (known as guano) are a valuable natural fertilizer. Although bats have almost no natural enemies, over past decades they have been facing numerous threats. All of these are related to human activity: habitat loss due to deforestation, changes in building style, and overhunting for bush meat are among them. Beyond this, the ever-more more aggressive use of pesticides in agriculture has also lead to a significant decline of insects - bats' main food source - thus poisoning bats. Contributing to the problem is the difficulty in tracking significant declines in bat populations - until their situation is critical. And bats' low reproduction rates - most females give birth to only one pup per year - make recovery from serious losses especially slow.

Agricultural systems are drivers of global environmental degradation. Insecticides, in particular, are highly biologically active substances that can threaten the ecological integrity of aquatic and terrestrial ecosystems. Despite widespread insecticide application to croplands worldwide, no comprehensive field data-based evaluation of their risk to global surface waters exists. Our data show, for the first time to our knowledge at the global scale, that more than 50% of detected insecticide concentrations (n = 11,300) exceed regulatory threshold levels. This finding indicates that surface water pollution resulting from current agricultural insecticide use constitutes an excessive threat to aquatic biodiversity. Overall, our analysis suggests that fundamental revisions of current regulatory procedures and pesticide application practices are needed to reverse the global environmental impacts of agrochemical-based high-intensity agriculture.

The autumn darter -- a species of red dragonfly -- is making it onto the "red list" of endangered species in many local municipalities in Japan. The data point to a possible link with the use of pesticides. According to the Nature Conservation Society of Japan (NACS-J), the autumn darter (Sympetrum frequens) has been confirmed as being on endangered species lists in the six prefectures of Osaka, Hyogo, Mie, Toyama, Nagasaki and Kagoshima. Their numbers have dropped dramatically from the late 1990s onward. According to Tetsuyuki Ueda, an animal ecology expert and professor emeritus at Ishikawa Prefectural University, autumn darters were confirmed to have emerged from their chrysalises at 80 percent of rice paddies in the prefecture in 1989, while the figure was down to 19 percent in 2009. Tests found that using neonicotinoid insecticides, which have become widespread since their emergence in the 1990s, led to a 70-percent drop in the autumn darter's eclosion rate than when such insecticides were not used.

Einst war die Feldlerche (Alauda arvensis) ein häufiger Brutvogel der Agrarlandschaft. Doch schon seit vielen Jahren geht ihr Bestand stetig zurück. Diese besorgniserregende Entwicklung war Anlass für die Hessische Gesellschaft für Ornithologie und Naturschutz (HGON), gemeinsam mit dem Naturschutzbund Deutschland (Nabu) den aktuellen Bestand der Feldlerche im Kreis Offenbach ein weiteres Mal zu erfassen. Mitglieder des Arbeitskreises Offenbach der HGON haben die Feldlerchenvorkommen im Kreisgebiet 1998 erstmals kartiert. Insgesamt wurden damals 460 Reviere ermittelt. Das Ergebnis der diesjährigen Erfassung war erschreckend. Mit lediglich 165 Revieren ist der Bestand in den zurückliegenden 17 Jahren um 64 Prozent zurückgegangen. Völlig verschwunden ist die Lerche in diesem Zeitraum aus Sprendlingen, Hainburg und Urberach. Drastische Rückgänge gab es mit rund 90 Prozent in Heusenstamm, 80 Prozent in Seligenstadt sowie je 73 Prozent in Egelsbach und Obertshausen. Im Rodgau, dem Hauptverbreitungsgebiet der Feldlerche im Kreis, ging die Zahl der Paare von 243 auf 81 zurück. Die Feldvögel sind inzwischen die am meisten gefährdete Artengruppe innerhalb der mitteleuropäischen Vogelfauna. Die Zunahme des Maisanbaus und der Einsatz von Pestiziden tragen dazu bei. Große Flächen mit blühendem Raps sind für viele zwar hübsch anzuschauen, stehen Feldlerche und anderen Vögeln der Agrarlandschaft als Brutrevier und zur Nahrungssuche aber nicht zur Verfügung.

A UK Government study by their agency Fera has been published today. The study contains three key results, it shows:-
• A clear relationship across regions between imidacloprid use (the commonest neonicotinoid used during the period of the study) and overwintering honeybee colony losses. • Neonicotinoid seed treatments (mainly imidacloprid) on Oilseed rape did not produce a consistent yield benefit - positive in three years, negative in one and no overall effect.
• Neonicotinoid use reduced insecticide spray use in the autumn only if the initial use of the neonicotinoid was ignored, but appeared to increase insecticide sprays the following spring – net effect circa 0.75 more insecticide uses per hectare. Government has been aware of this statistical link between imidacloprid use and honeybee colony loss since early 2013 – the minutes of their own Advisory Committee on Pesticides of 29th January 2013 contain extensive discussion about a “prepublication” analysis that revealed that once regional differences had been accounted for 7-8% of honeybee colony loss was associated with imidacloprid use “there was a clear signal from imidacloprid use despite this ‘noise’, from other factors”.

Canada is home to billions of birds belonging to some 451 regularly occurring native species that raise their young or spend their non-breeding seasons in this vast and varied country. Increasingly, these birds face many threats here and elsewhere. On average, Canadian breeding bird populations have decreased 12% since 1970 when effective monitoring began for most species. Some groups, such as grassland birds, aerial insectivores and shorebirds, are showing major declines. Aerial insectivores—birds that catch insects in flight—are declining more steeply than any other group of birds. Some formerly very common species like the Barn Swallow and Chimney Swift have declined to less than a quarter of their 1970-level populations.

In the first national-scale investigation of neonicotinoids in streams, the U.S. Geological Survey found that in more than half of urban and agricultural streams sampled, the pesticide could be detected. The study, conducted from 2011 to 2014, is published in Environmental Chemistry. It spanned 24 states and Puerto Rico and was completed as part of ongoing USGS stream sampling. "In the study, neonicotinoids occurred throughout the year in urban streams while pulses of neonicotinoids were typical in agricultural streams during crop planting season," said USGS research chemist Michelle Hladik, the report's lead author. "The occurrence of low levels in streams throughout the year supports the need for future research on the potential impacts of neonicotinoids on aquatic life and terrestrial animals that rely on aquatic life," said USGS scientist Kathryn Kuivila, the research team leader. "These results will serve as an important baseline for that future work." The study is the first step in setting priorities for exposure experiments and identifying adverse effects to animals and wildlife near or in streams. Agriculture groups and others have been monitoring discussion about neonicotinoids' effects on non-target insects, especially pollinating honey bees and native bees.

Starting from a homology model of the active site of the nicotinic acetylcholine receptor (nAChR) of sensitive pest insects, such as aphids (here, Myzus persicae), a hypothesis for the mode of binding was created for five small-molecule agonists of the nAChR, representing all four chemical subclasses of group 4 in the Insecticide Resistance Action Committee (IRAC) mode of action (MoA) classification scheme. Docking poses of these agonists in the active site of the homology model revealed two major interactions that are common across all investigated compounds: 1) a water-mediated hydrogen bridge towards the backbone of the b subunit of the receptor. 2) an interaction with a conserved cluster of aromatic residues from the a subunit. Interactions 1 and 2 result in nice spatial alignment of all five agonists within the active site. 3) The four synthetic agonists carry a head group that forms a hydrogen bridge towards a charged arginine residue from the b subunit, which is known to be crucial for high-affinity binding and pest sensitivity. Interaction 3 is not only absent for the vertebrate toxic plant derived alkaloid nicotine, but is replaced by a weak electrostatic repulsion.