Fewer poisoned bees

Since the early 1960s, the number of bees poisoned by insecticides has fallen by 95 per cent. Now there are less than 10 recorded cases each year.

Things are looking up for the Danish honey bees. There are now far fewer bees getting poisoned by agricultural insecticides.

Every year bee farmers send in dead bees for toxicological examinations. The cause can be put down to poisoning for only half of these. Since the early 1960s, the incidence of bee fatalities from poisoning has fallen by 95 per cent and currently there are fewer than 10 such cases recorded each year.

Lars Monrad Hansen, who is senior scientist at the Danish Institute of Agricultural Sciences (DIAS), has studied the closer details of honey bee poisoning. He explains that scientists at DIAS have developed a method to identify the insecticide responsible when bees die from poisoning. The new method consists of an advanced form of mass spectroscopy that is able to detect the tiniest amounts of insecticide.

- In the relatively few cases of poisoning in recent years the culprit has nearly always been insecticides that contain the active ingredient dimethoate. It is therefore important that farmers take serious heed of the safety warnings on the label and refrain from using the insecticide on crops in open flower, points out Lars Monrad Hansen.

There are probably many reasons why there has been a large fall in the number of bee poisonings, but an important cause has been the change to another active ingredient. In the 1980s, pyrethroids started to dominate the market. With recent scientific advances, less than 10 g is now needed per hectare of this insecticide in its most toxic form. As bees are repelled by pyrethroids, they are rarely poisoned by them.

Another explanation for the fall in the number of poisonings is the increased awareness over the last 50 years of the problems caused by the use of insecticides. The collaboration between scientists, advisors and farmers has meant that they now know when and when not to spray. Both the amount of insecticide and the number of applications have been reduced.

For further information please contact:

Senior scientist Lars Monrad Hansen, Department of Integrated Pest Management, Research Centre Flakkebjerg, telephone: +45 8999 3638, mobile: +45 2228 3334, e-mail: [email protected]