April 5, 2012
The Guardian , March 29, 2012
Pesticides linked to honeybee decline
The first study conducted in a natural environment has shown that systemic pesticides damage bees’ ability to navigate
By Damian Carrington
Common crop pesticides have been shown for the first time to seriously harm bees by damaging their renowned ability to navigate home.
The new research strongly links the pesticides to the serious decline in honey bee numbers in the US and UK – a drop of around 50% in the last 25 years. The losses pose a threat to food supplies as bees pollinate a third of the food we eat such as tomatoes, beans, apples and strawberries.
Scientists found that bees consuming one pesticide suffered an 85% loss in the number of queens their nests produced, while another study showed a doubling in “disappeared” bees – those that failed to return from food foraging trips. The significance of the new work, published Science, is that it is the first carried out in realistic, open-air conditions.
“People had found pretty trivial effects in lab and greenhouse experiments, but we have shown they can translate into really big effects in the field. This has transformed our understanding,” said Prof David Goulson, at the University of Stirling and leader of one of the research teams. “If it’s only one metre from where they forage in a lab to their nest, even an unwell bee can manage that.”
Prof Mickaël Henry, at INRA in Avignon, France, who led a separate research team, said: “Under the effects we saw from the pesticides, the population size would decline disastrously, and make them even more sensitive to parasites or a lack of food.”
The reason for the huge decline in bee numbers has remained uncertain, but pesticides, the varroa mite and other parasites, and destruction of the flower-rich habitats in which bees feed are believed to be the key reasons. Pesticide manufacturers and the UK government deny a class of the chemicals called neonicotinoids cause significant problems for bees, but Germany, Italy and France have suspended key insecticides over such fears.