Insecticiden

Reports of bat deaths worldwide due to human causes largely unique to the 21st century are markedly rising, according to a new USGS-led analysis published in Mammal Review. Collisions with wind turbines worldwide and the disease white-nose syndrome in North America lead the reported causes of mass death in bats since the onset of the 21st century. These new threats now surpass all prior known causes of bat mortality, natural or attributed to humans. A comprehensive study reveals trends in the occurrence and causes of multiple mortality events in bats as reported globally for the past 200 years, shedding new light on the possible factors underlying population declines. "Many of the 1,300 species of bats on Earth are already considered threatened or declining. Bats require high survival to ensure stable or growing populations," said Tom O'Shea, a USGS emeritus research scientist and the study's lead author. "The new trends in reported human-related mortality may not be sustainable."

It has been suggested that several neonicotinoids cause neurodevelopmental toxicity in mammals. The aim was to establish the relationship between oral intake and urinary excretion of neonicotinoids by humans to facilitate biological monitoring, and to estimate dietary neonicotinoid intakes by Japanese adults. Deuterium-labeled neonicotinoid (acetamiprid, clothianidin, dinotefuran, and imidacloprid) microdoses were orally ingested by nine healthy adults, and 24 h pooled urine samples were collected for 4 consecutive days after dosing. The excretion kinetics were modeled using one- and two-compartment models, then validated in a non-deuterium-labeled neonicotinoid microdose study involving 12 healthy adults. Increased urinary concentrations of labeled neonicotinoids were observed after dosing. Clothianidin was recovered unchanged within 3 days, and most dinotefuran was recovered unchanged within 1 day. Around 10% of the imidacloprid dose was excreted unchanged. Most of the acetamiprid was metabolized to desmethyl-acetamiprid. Spot urine samples from 373 Japanese adults were analyzed for neonicotinoids, and daily intakes were estimated. The estimated average daily intake of these neonicotinoids was 0.53–3.66 μg/day. The highest intake of any of the neonicotinoids in the study population was 64.5 μg/day for dinotefuran, and this was <1% of the acceptable daily intake.

Mayfly nymphs are among the most sensitive taxa to neonicotinoids. The present study presents the acute and chronic toxicity of 3 neonicotinoids (imidacloprid, thiacloprid, and thiamethoxam) to a mayfly species (Cloeon dipterum) and some notes on the seasonality of the toxicity of imidacloprid to C. dipterum and 5 other invertebrate species. Imidacloprid and thiamethoxam showed equal acute and chronic toxicity to a winter generation of C. dipterum, whereas thiacloprid was approximately twice as toxic. The acute and chronic toxicity of imidacloprid was much higher for the C. dipterum summer generation than for the winter one. The acute toxicity differs by a factor of 20 for the 96-h 50% effective concentration (EC50) and by a factor of 5.4 for the chronic 28-d EC50. Temperature had only a slight effect on the sensitivity of C. dipterum to imidacloprid because we only found a factor of 1.7 difference in the 96-h EC50 between tests performed at 10 8C and 18 8C. The difference in sensitivity between summer and overwintering generations was also found for 3 other insect species. The results indicate that if the use and environmental fate of the 3 neonicotinoids are comparable, replacing imidacloprid by another neonicotinoid might not reduce the environmental impact on the mayfly nymph C. dipterum. The results also show the importance of reporting which generation is tested because sensitivity values of insects in the summer might be underestimated by the experiments performed with neonicotinoids and an overwintering population.

Der Imkerverein Lingen hat bei seiner Generalversammlung verdiente Imker ausgezeichnet. Darüber hinaus zeigten sich die Imker besorgt über die Auswirkungen der Veränderungen der Landschaft auf die Imkerei. Den Beobachtungen der Imker zufolge nimmt seit den 1950er Jahren die Zahl der Hummeln, Wildbienen und Schmetterlinge dramatisch ab. Das zeige, dass unsere Landschaft sich dramatisch verändert habe, heißt es in einer Pressemitteilung der Imker. Es gebe nicht mehr grün blühende Wiesen, Ackerflächen mit Wildblumen umrankt, Kornblumen, Kleearten und Wildkräuter, Wald und Moore. Alles sei hauptsächlich in Agrarlandschaft umgewandelt. Viele nützliche Insekten ernähren sich nach Angaben der Imker heute von ganz anderen Pflanzen als noch vor 50 Jahren. Denn die Blüten, die sie eigentlich bevorzugen, gebe es heute gar nicht mehr. Der Einsatz von Insektiziden im deutschen Rapsanbau hat sich den Lingenern zufolge vervierfacht. Dennoch hätten es die Imker erreicht, das die Bienen auch weiter in unserer Landschaft bestäubend tätig sind. Dieses Wissen müsse an die jungen Imker weiter gereicht werden, hieß es.

DW looks at why people are taking to the streets in Germany to demand an "Agrarwende" - or agricultural transformation. Issues include health concerns, protection of animals, and pollution impacts on water and climate. Under the motto "we're sick of it!", people in Berlin will hit the streets by the thousands on Saturday (01.16.2016) to protest for a transformation in agricultural systems. A broad coalition of more than 50 environmental, consumer, animal and farming groups have called for the demonstration, which coincides with the opening of Green Week in Berlin - the largest agricultural trade fair in the world.

Bumblebees are exposed to pesticides applied for crop protection while foraging on treated plants, with increasing evidence suggesting that this sublethal exposure has implications for pollinator declines. The challenges of navigating and learning to manipulate many different flowers underline the critical role learning plays for the foraging success and survival of bees. We assessed the impacts of both acute and chronic exposure to field-realistic levels of a widely applied neonicotinoid insecticide, thiamethoxam, on bumblebee odour learning and memory. Although bees exposed to acute doses showed conditioned responses less frequently than controls, we found no difference in the number of individuals able to learn at field-realistic exposure levels. However, following chronic pesticide exposure, bees exposed to field-realistic levels learnt more slowly and their short-term memory was significantly impaired following exposure to 2.4 ppb pesticide. These results indicate that field-realistic pesticide exposure can have appreciable impacts on learning and memory, with potential implications for essential individual behaviour and colony fitness.

The dramatic loss of honey bees is a major concern worldwide. Previous studies have indicated that neonicotinoid insecticides cause behavioural abnormalities and have proven that exposure to sublethal doses of imidacloprid during the larval stage decreases the olfactory learning ability of adults. The present study shows the effect of sublethal doses of imidacloprid on the neural development of the honey bee brain by immunolabelling synaptic units in the calyces of mushroom bodies. We found that the density of the synaptic units in the region of the calyces, which are responsible for olfactory and visual functions, decreased after being exposed to a sublethal dose of imidacloprid. This not only links a decrease in olfactory learning ability to abnormal neural connectivity but also provides evidence that imidacloprid damages the development of the nervous system in regions responsible for both olfaction and vision during the larval stage of the honey bee.

"Unsere Beobachtungen sind hochgradig beängstigend", sagt Josef Tumbrinck vom Naturschutzbund Deutschland (Nabu). Er warnt vor einem neuartigen Insektensterben mit unbekannten Folgen für Deutschland. Nach einer aktuellen Untersuchung ging im Bundesland Nordrhein-Westfalen in den vergangenen 15 Jahren die Masse an Insekten um 80 Prozent zurück. Eine ähnliche Entwicklung wird auch in anderen Regionen befürchtet. "Wenn uns die Fluginsekten fehlen, gerät die gesamte Nahrungskette in Gefahr: Blumen und Bäume werden nicht mehr bestäubt, und den Vögeln fehlt die Nahrungsgrundlage", sagt Tumbrinck, Vorsitzender vom Nabu in NRW. Der Umweltverband hatte zusammen mit Insektenkundlern zwischen 1989 und 2014 an 88 Standorten Insekten gesammelt, ihre Arten bestimmt und sie gewogen. "Während wir 1995 noch 1,6 Kilogramm aus den Untersuchungsfallen sammelten, sind wir heute froh, wenn es 300 Gramm sind", sagt Tumbrinck. Der Rückgang von bis zu 80 Prozent betreffe unter anderem Schmetterlinge, Bienen und Schwebfliegen. Besonders Neonicotinoide stehen im Verdacht, für das massenhafte Sterben von Insekten verantwortlich zu sein. Die hochwirksamen Insekten-Nervengifte werden seit Mitte der 1990er Jahre in der Landwirtschaft eingesetzt.