Insecticiden

Industrial agriculture, with its heavy use of chemical pesticides, pollutes our water and soil and leads to loss of habitats and biodiversity, according to a Greenpeace report. With almost one in four (24.5%) vulnerable or endangered species in the EU being threatened by agricultural effluents, including the use of pesticides and fertilizers, species survival and crucial ecosystem services, like pollination, are at risk. Political and financial support is urgently needed to shift from chemical-intensive, damaging agricultural methods, to sustainable ecological farming practices. In Europe, a catastrophic decline of insects was signaled by the "IUCN Task Force on Systemic Pesticides" in 2015, after analyzing over 800 scientific reports. The impacts can be devastating, as 70 per cent of the 124 major commodity crops directly used for human consumption like apples and rapeseed are dependent on pollination for enhanced seed, fruit, or vegetable production. Dirk Zimmermann, Ecological Farming Campaigner at Greenpeace Germany said: "Europe's dependency on chemical pesticides is nothing short of an addiction. Crops are routinely doused with a variety of chemicals, usually applied multiple times to single crops throughout the whole growing season. Non-chemical alternatives to pest management are already available to farmers but need the necessary political and financial support to go mainstream."

In ihrer Studie untersuchten die Wissenschafter die Wirkung von zwei verbreiteten Neonikotinoiden (Thiamethoxam und Clothianidin) auf Bienenköniginnen. In der EU und der Schweiz ist die Anwendung dieser und weiterer Substanzen seit Ende 2013 für zwei Jahre stark eingeschränkt. Die Idee hinter diesem Moratorium: Die Zeit sollte genutzt werden, um den Einfluss der umstrittenen Gifte auf das Bienensterben zu untersuchen. Genau das hat die schweizerisch-kanadische Arbeitsgruppe getan. Sie konzentrierte sich auf die Königinnen, weil Umfragen bei Imkern den Verdacht aufkommen liessen, dass diese Tiere beim Bienensterben eine Schlüsselrolle spielen könnten. In der Studie seien die Bienenköniginnen dem Thiamethoxam und dem Clothianidin in einer realistischen Umgebungskonzentration ausgesetzt worden, schreiben die Forscher. Dies hatte gravierende Auswirkungen auf die Fruchtbarkeit der Königinnen, wie die Wissenschafter in der Fachzeitschrift «Scientific Reports» schreiben. Bei den Tieren stellten sich sowohl anatomische wie auch physiologische Veränderungen ein. So wiesen sie vergrösserte Eierstöcke auf und konnten weniger Spermien von männlichen Bienen (Drohnen) speichern. Insgesamt waren die Bienenköniginnen dadurch weniger erfolgreich beim Eierlegen.

Queen health is crucial to colony survival of social bees. Recently, queen failure has been proposed to be a major driver of managed honey bee colony losses, yet few data exist concerning effects of environmental stressors on queens. Here we demonstrate for the first time that exposure to field-realistic concentrations of neonicotinoid pesticides during development can severely affect queens of western honey bees (Apis mellifera). In pesticide-exposed queens, reproductive anatomy (ovaries) and physiology (spermathecal-stored sperm quality and quantity), rather than flight behaviour, were compromised and likely corresponded to reduced queen success (alive and producing worker offspring). This study highlights the detriments of neonicotinoids to queens of environmentally and economically important social bees, and further strengthens the need for stringent risk assessments to safeguard biodiversity and ecosystem services that are vulnerable to these substances.

Farmland is home to hundreds of plant and thousands of animal species, many of which are highly dependent on each other forming a complex food web. This was first revealed by our early work on the grey partridge in Sussex. The population of grey partridge was partially dependent on the survival rate of the chicks, which in turn depended on them sourcing enough protein-rich insects. The insects that were most important to the chicks were largely weed-feeding species, and as a consequence, insect abundance was controlled by the management of the crop, but especially by the levels of herbicide inputs. Thus, herbicides were identified as causing an indirect effect on the number of insects within the crop, but also ultimately on the population of grey partridge. Herbicides also reduce the abundance of vegetation and weed seed that are important food sources for insects, birds and small mammals. The indirect effects of pesticides are now a recognised phenomena and along with direct effects are considered responsible for the decline of many other farmland birds because all of them, with the exception of pigeons and doves, feed their young insects during the first few weeks. Autoecological studies have helped to identify the causes behind the decline of some farmland bird species, such as those conducted on grey partridge, corn bunting and yellowhammer. These revealed a strong relationship between invertebrate food availability during breeding and breeding success and this was consequently linked to population change. The majority of other farmland birds also feed their chicks invertebrates because they provide the necessary protein for growth and the energy to resist chilling.

In recent years, an intense debate has been generated about the environmental risks posed by neonicotinoids, a group of widely-used, neurotoxic insecticides. When these systemic compounds are applied to seeds, low concentrations are subsequently found in the nectar and pollen of the crop, which are then collected and consumed by bees. Here we demonstrate that current focus on exposure to pesticides via the crop overlooks an important factor – throughout spring and summer, mixtures of neonicotinoids are also found in the pollen and nectar of wildflowers growing in arable field margins, at concentrations that are sometimes even higher than those found in the crop. Indeed the large majority (97%) of neonicotinoids brought back in pollen to honey bee hives in arable landscapes was from wildflowers, not crops. Both previous and ongoing field studies have been based on the premise that exposure to neonicotinoids would only occur during the blooming period of flowering crops and that it may be diluted by bees also foraging on untreated wildflowers. Here, we show that exposure is likely to be higher and more prolonged than currently recognized due to widespread contamination of wild plants growing near treated crops.

In response to a petition from the Center for Biological Diversity, the U.S. Fish and Wildlife Service today announced that the tricolored blackbird (Agelaius tricolor) may qualify for federal Endangered Species Act protection. The Center petitioned to protect tricolored blackbirds under both the federal and California Endangered Species Acts after dramatic declines of nesting colonies due to loss of wetlands and native grasslands, shooting, pesticide use and mass destruction of nests through mowing and harvest of crops the birds use for nesting in California. “Tricolored blackbirds once formed massive nesting colonies of millions of birds in California’s Central Valley but are now suffering declines comparable to the extinction trajectory of the passenger pigeon,” said the Center’s Jeff Miller. “Endangered Species Act protection is needed to safeguard their vulnerable breeding colonies, especially since the state of California has inexplicably delayed protection for tricoloreds despite warnings by biologists that we could lose this species entirely.” Comprehensive statewide surveys found only 395,000 tricolored blackbirds in 2008, followed by a decline to 259,000 in 2011 and only 145,000 in 2014 — the smallest population ever recorded.