Hommels

The Ontario government has unveiled North America’s first agricultural restrictions on a widely used class of pesticides blamed for the decline in bees and other pollinators.The controversial regulations aimed at reducing the use of neonicotinoid insecticides made by Bayer AG and Syngenta AG by 80 per cent within two years goes into effect on July 1. The province said on Tuesday it wants to reduce the overwintering death rate of honey bees to 15 per cent from an average of 34 per cent by controlling the planting of seeds treated with the three most commonly used neonicotinoids. Glen Murray, Ontario’s Minister of the Environment, said the rules are “highly workable” and address farmers’ concerns while reducing damage from neurotoxic pesticides that are persisting in streams and soil and affecting everything from birds and bees to butterflies and aquatic life. The rules, which are intended to improve the health of insects responsible for pollinating about $900-million worth of crops, require that farmers who use neonic-treated seeds to grow corn and soybeans show they have insect problems, and that seed vendors be licensed. Vendors of other pesticides require licences, and the new Ontario rules simply add neonics to that regime, he noted. Establishing, administering and enforcing the licensing and planting system will cost $3-million to $4-million a year, said Mr. Murray, conceding there is little to prevent anyone from purchasing the treated seeds in the United States.

In a recent issue of the journal Science, Dave Goulson and colleagues presented a review entitled “Bee declines driven by combined stress from parasites, pesticides, and lack of flowers”. This stimulated Jaboury Ghazoul to submit a letter to Science criticising the Goulson et al. paper from a number of perspectives, but particularly the paucity of the evidence base for pollinator declines. Dave and his co-authors robustly responded to that letter, as you might imagine. In some respects this was an unsatisfactory exchange, however, as the focus was largely on agricultural pollinators, rather than pollinators of all plants (including the majority non-cultivated species) and I think that (perhaps with more space?) Dave could have outlined the evidence in more depth. The most striking statement in Jaboury’s letter was that the “evidence for pollinator declines is almost entirely confined to honeybees and bumblebees in Europe and North America”. Now, even given the fact that Jaboury was possibly referring specifically to agricultural pollinators, that is a very extreme statement to make. Underlying it is the suggestion that global concerns about declining pollinator biodiversity (a subject I’ve discussed repeatedly on this blog) is underpinned by a taxonomically and geographically thin evidence base. Is that really true? I don’t believe so and I think it’s worth presenting a brief overview of the evidence, not least because Dave’s review and the resulting correspondence is pay-walled at the Science site (though if you Google the titles you might, just might, find copies posted on the web…).

Scientists have reported that a certain class of pesticides is turning bees into zombies by killing vital brain cells, leaving them unable to learn, gather food and reproduce. In a research report published in the FASEB Journal, scientists report that a particular class of pesticides called "neonicotinoids" wreaks havoc on the bee populations, ultimately putting some crops that rely on pollination in jeopardy. Specifically, these pesticides kill bee brain cells, rendering them unable to function and survive. "Our study shows that the neonicotinoid pesticides are a risk to our bees and we should stop using them on plants that bees visit," said Christopher N. Connolly, Ph.D., a researcher involved in the work from the Medical Research Institute at the Ninewells Medical School at the University of Dundee. To make their discovery, Connolly and colleagues fed bees a sugar solution with very low neonicotinoid pesticide levels typically found in flowers (2.5 parts per billion) and tracked the toxins to the bee brain. They found that pesticide levels in the bees' brains were sufficient to cause the learning cells to run out of energy. Additionally, the brain cells were even vulnerable to this effect at just one tenth of the level present.

Bienen fliegen auf bestimmte Pflanzenschutzmittel: Sie meiden mit sogenannten Neonicotinoiden behandelte Pflanzen nicht etwa, sondern steuern sie wohl sogar bevorzugt an. Beim Sammeln von Nektar und Pollen könnten sie deshalb mehr von den Schadstoffen aufnehmen als bisher angenommen, schreiben Forscher aus Großbritannien und Irland im Fachblatt „Nature“. In einer zweiten Studie fanden schwedische Wissenschaftler, dass die Mittel Wachstum und Vermehrung von Wildbienen und Hummeln beeinträchtigen können. „Neonicotinoide steuern im Nervensystem von Bienen die gleichen Mechanismen an wie Nikotin im Gehirn von Menschen“, erläutert die Studienleiterin Geraldine Wright von der Newcastle University. „Die Tatsache, dass die Bienen eine Vorliebe für Neonicotinoid-belastete Nahrung haben, ist besorgniserregend, weil es vermuten lässt, dass die Neonicotinoide ähnlich wie Nikotin als Droge wirken und solche Nahrung besonders belohnend wirkt.“

For the first time, a research project has investigated how a neonicotinoid pesticide, clothianidin, affects both honeybees and wild bees under field conditions in agricultural landscapes. The study shows that honeybees can cope with exposure to the pesticide, but that it has a strong negative impact on wild bees. The researchers, from Lund University and Swedish University of Agricultural Sciences, in collaboration with the Swedish Board of Agriculture, have investigated how the neonicotinoid clothianidin affects domesticated and wild bees under Swedish field conditions. The research findings have now been published in the scientific journal Nature, and they show that the insecticide has a negative impact on wild bees. This is severe, because wild bees play an important role in pollination of crops. Wild bees are in Sweden bumblebees and solitary bees. “We saw a clear negative impact on growth and reproduction in bumblebee colonies near treated oilseed rape fields”, said Maj Rundlöf from Lund University, the coordinator and principal investigator for the field study.

Es ist lange bekannt, dass bestimmte Pestizide schädlich für den Bestand von Honigbienen sein können. Dennoch tun sich Politiker schwer damit, die Chemikalien zur Schädlingsbekämpfung gänzlich zu verbieten. Nun melden sich Wissenschaftler in der Europäischen Union zu Wort. Sie bestätigen, dass der Einsatz bestimmter Gifte für das Bienensterben verantwortlich ist. Es gebe starke Beweise für die negativen Auswirkungen auf andere Organismen durch Neonicotinoid-Insektizide, heißt es in einer am Mittwoch veröffentlichten Studie des EU-Wissenschafsnetzwerks Easac. In dem Bericht werden die Befunde einer Expertengruppe von 13 Forschern zusammengefasst. Das Netzwerk berät Entscheidungsträger in der EU. Die EU-Kommission überprüft bis Dezember die vor zwei Jahren verhängten Beschränkungen für die Pflanzenschutzmittel, die überwiegend von Bayer aus Leverkusen und Syngenta aus der Schweiz produziert werden. Die Mittel werden in mehr als 120 Ländern eingesetzt. Dem Bericht der Wissenschaftler zufolge sind vom Einsatz der Insektizide nicht nur Honigbienen, sondern auch Motten und Schmetterlinge betroffen, die ebenfalls Pflanzen bestäuben. Auch auf insektenfressende Vögel hätten die Pestizide Auswirkungen. Der Studie zufolge drohe durch Pestizideinsatz ein "Bestäubungs-Defizit" - da immer mehr Nutzpflanzen angebaut werden, die in ihrer Entwicklung auf die Bestäubung der Bienen angewiesen sind.