Hommels

Exposure to even small amounts of pesticides is preventing bumblebees from efficiently extracting pollen from their favourite wildflowers, says a new study, raising concerns that the chemicals are impairing the insects' ability to learn.
And scientists warn that could affect the ability of the bees to pollinate both crops and wild plants, which can ultimately harm the food supply. The findings, contained in a study co-authored in Canada and the U.K., show that bumblebees exposed to a realistic level of a neonicotinoid insecticide called thiamethoxam, collected more pollen, but took longer to do so than control bees. The study, published Monday in Functional Ecology, found that low exposure to the crop chemical can hinder the ability of bumblebees to develop the skills they need to collect nectar and pollen. While several studies have been conducted on the effects of pesticides on the honeybee population, these findings are the first to explore how the chemicals may affect the ability of bumblebees to forage from common wildflowers. The pesticides confuse the insects, changing their foraging behaviour and floral preferences and hindering the development of the skills needed to extract nectar and pollen, says University of Guelph professor and senior author Nigel Raine.

An international science body tasked with tracking the ecological health of the planet has announced the findings of its first report. The review warns that the ongoing decline in the number of pollinating insects and animals threatens global crop production. The Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services (IPBES) was established in 2012, and is roughly modelled on the Intergovernmental Panel on Climate Change (IPCC). The reponse to the pollinator report, announced on 26 February at a meeting in Kuala Lumpur, may be an early sign of whether the body's influence will one day match the IPCC's political and scientific clout. Robert Watson, an environmental scientist at the Tyndall Centre for Climate Change at the University of East Anglia in Norwich, UK, who is vice-chairman of the IPBES, says that he is confident that the assessment will have an impact. The IPBES has 124 member governments, and its pollinator assessment went through two rounds of external peer review. And just as with the IPCC’s climate reports, the assessment was debated word for word, Watson says. “The fact that all governments requested this document really bodes well that they will use the results,” he says. But Dave Goulson, a bee researcher at the University of Sussex in Brighton, UK, says: “I would question whether any practical on-the-ground action to help pollinators will happen as a result of this document. We are in the midst of the sixth global mass-extinction event, and we sit around spending thousands of hours writing documents about biodiversity, but we do not take action to address the fundamental issues that are causing this ecological catastrophe.”

The results show that, in the same two areas, sampled in the years 1989 and 2013, there was a dramatic fall in the number of flying insects. Using the same traps, in the same areas, significant reductions of insect populations, of more than 75%, were found. Our data confirms, that in the areas studied, less than 25% of the original number of flying insects collected in 1989, were still present in 2013.

In Krefeld sind in den vergangenen Jahrzehnten von 28 dokumentierten Hummel-Arten 19 ausgestorben; bei den verbleibenden neun Arten geht die Zahl der Individuen beständig zurück. Das ist unterm Strich das Ergebnis von Insektenzählungen, die Fachleute des Krefelder Entomologischen Vereins betreiben. Die Hummeln haben damit Anteil an einem dramatischen Rückgang der Insektenbestände, auf den die Entomologen seit langer Zeit hinweisen - und vor dem sie warnen: "Jede Art hat ihre Funktion im Naturhaushalt; wenn man eine Art verliert, verliert man deren besondere Fähigkeiten", sagt Andreas Müller, Vorsitzender des Entomologischen Vereins Krefeld, "wir wissen nicht, was mit unseren Ökosystemen und unseren Naturschutzgebieten in der Zukunft passiert, wenn man immer mehr Funktionen herausnimmt." Die Krefelder Entomologen betreiben seit 30 Jahren systematisch Insektenzählungen, auch mit neueren Methoden wie den sogenannten Malaise-Fallen, unter anderem im Orbroicher Bruch und im Latumer Bruch. Die so gefangenen Insekten werden dokumentiert und gezählt. "Das Ergebnis ist ein sehr beunruhigender Rückgang an Arten und auch an Masse", resümiert Heinz Schwan, Ehrenvorsitzender des Entomologischen Vereins, "die Hummeln haben Anteil an dieser Entwicklung, die man auch anhand der Entomologischen Sammlungen gut nachvollziehen kann".

Like many other area farmers, the Bredeson family in Harvey Township, between Grove City and Litchfield, buys corn and soybeans seeds treated with pesticides. Pesticides are designed to improve crop yields, but they have side effects, and the family has been learning more about these effects from an expert — Mark and Julie Bredeson’s own son, Michael. “He’s kind of on the cutting edge of finding that these pesticides that farmers have been using for many years have become a detrimental thing to not only agriculture but mother nature,” Julie said about Michael’s work. Michael, a 2008 Litchfield High School graduate, is pursuing his Ph.D. at South Dakota State University, where he studies the effects of pesticides on organisms, particularly linked to sunflowers, a common cash crop in South Dakota. In commentary in the Independent Review (see below), Michael writes about pesticides’ effects and the long-term implications for birds, reptiles, mammals, fish and plants. Julie and Michael said they’ve both noticed a reduction in wildlife at and near the family’s Meeker County farm over the years. As he grew older, Michael noticed a decline in good fishing holes, which he attributes to runoff from crop fields. “My life revolved around fishing on all the little lakes. A few of my great fishing spots died off, and that kind of irritated me, of course,” he said. Julie said she’s also witnessed a decline in wildlife since she was a child. “The landscape as far as our wildlife, butterflies and bees, has dramatically changed,” she said. “It’s something we need to think about.”

The first ever Britain-wide assessment of the value of wild flowers as food for pollinators, led by the University of Bristol, shows that decreasing resources mirror the decline of pollinating insects, providing new evidence to support the link between plant and pollinator decline. In recent years, there have been considerable concerns over threats to wild bees and other insect pollinators which are vital to the success of important food crops and wild flowers. Amongst the many pressures facing pollinators, a key factor is likely to be decreasing floral resources in Britain. The study, published today in Nature combines vegetation survey data recorded over the last 80 years with modern day measurements of nectar to provide the most comprehensive assessment ever published. In the study, researchers from the University of Bristol and University of Leeds worked with scientists from the Centre for Ecology and Hydrology and Fera Science Ltd, to find substantial losses to nectar resources in England and Wales between the 1930s and 1970s – a period closely linked with agricultural intensification.

Outbreaks of infectious diseases in honey bees, fish, amphibians, bats and birds in the past two decades have coincided with the increasing use of systemic insecticides, notably the neonicotinoids and fipronil. A link between insecticides and such diseases is hypothesised. Firstly, the disease outbreaks started in countries and regions where systemic insecticides were used for the first time, and later they spread to other countries. Secondly, recent evidence of immune suppression in bees and fish caused by neonicotinoids has provided an important clue to understand the sub-lethal impact of these insecticides not only on these organisms, but probably on other wildlife affected by emerging infectious diseases. The negative impacts of pesticides, in particular insecticides, on bees and other pollinators have never been disputed. Insecticides can directly kill these vital insects, whereas herbicides reduce the diversity of their food resources, thus indirectly affecting their survival and reproduction. At sub-lethal level (bLD50), neurotoxic insecticide molecules are known to influence the cognitive abilities of bees, impairing their performance and ultimately impacting on the viability of the colonies. In addition, widespread systemic insecticides appear to have introduced indirect side effects on both honey bees and wild bumblebees, by deeply affecting their health. Immune suppression of the natural defences by neonicotinoid and phenyl-pyrazole (fipronil) insecticides opens the way to parasite infections and viral diseases, fostering their spread among individuals and among bee colonies at higher rates than under conditions of no exposure to such insecticides. This causal link between diseases and/or parasites in bees and neonicotinoids and other pesticides has eluded researchers for years because both factors are concurrent: while the former are the immediate cause of colony collapses and bee declines, the latter are a key factor contributing to the increasing negative impact of parasitic infections observed in bees in recent decades.

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.