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Bee dying Two insecticides harm queen bees
For years, pesticides have been suspected of being the cause of bee mortality. An international research team now concludes that two insecticides from the group of neonicotinoids harm the reproduction of queen bees. The experts call for thorough environmental impact assessments of pesticides.
Parasites and insecticides responsible for bee mortality
In addition to imported parasites, agricultural insecticides have been suspected for years of being responsible for the worldwide deaths of bee colonies. The University of Bern has now announced in a press release that contradictory studies have so far made no clear conclusions about their effect on beneficial organisms. However, surveys of beekeepers in several countries have suggested that the loss of entire colonies may be linked to the health problems of queen bees.
Some insecticides cause dying queen bees. (Image: Heinz Waldukat / fotolia.com) Queen Bees less successful at laying eggs
An international research team under Swiss leadership has now for the first time investigated the effects of insecticides from the group of neonicotinoids on the reproduction of queen bees. Employees of the Institute for bee health of the University of Bern, the agricultural research institute Agroscope and the Canadian Acadia University were involved. In the Scientific Reports journal of the Nature publishing group, the scientists reported that the examined queens had enlarged ovaries, were less able to store sperm from male bees (drones), and were less successful at laying eggs. The reported insecticide concentrations were in the "realistic field" range.
Several drugs were banned years ago
"The results show that these chemicals damage queens and may be responsible for the losses of bee colonies," said first author Geoffrey Williams of the University of Bern. As a precautionary measure, the use of three active substances from the group of neonicotinoids in Europe was severely restricted for two years in 2013 in order to investigate the effects on bee health in more detail. Only a few months ago a court ruling had been issued in Germany, according to which certain Bayer pesticides may be called bees dangerous. The lawsuit involved two products containing the neonicotinoid drug thiacloprid, which has been scientifically evaluated as "bee-friendly". The currently banned chemicals include thiamethoxam, clothianidin and imidacloprid, the first two of which were studied in the present study and showed a significant negative effect on the queen bees.
"Worrying but not surprising "
Dr. Agroscope's Laurent Gauthier said, "The results of the study are worrying but not surprising." According to the researchers, these chemicals are not as harmless to beneficial organisms as originally thought. Scientists call for more thorough environmental impact assessments of neonicotinoids to protect bees and other beneficials. German experts take their demands a step further. For example, the Bioland Bundesverband recently demanded a pesticide levy and a quick ban on particularly dangerous agricultural poisons. Among other things, they had cited the better protection of the bees as a reason.
Bee colony can not survive without queen
In every bee colony there is only one queen. Only she can lay eggs and is therefore central to the offspring in the people. It also ensures the social cohesion of the people through the production of pheromones. "Without them, the people would no longer survive in no time," said co-author Professor Peter Neumann from the Institute for bee health of the University of Bern. Millions of honeybee colonies in Europe and North America produce honey and pollinate plants. The variety of bee-pollinated plants ranges from carrots to almonds to rape. The total pollination output is several billion euros per year. (Ad)