Pesticides contributing to decline in bee numbers

Date:04-06-2011

Pesticides are not solely to blame for the decline in British bee numbers but are a contributing factor, an expert has said.

Research leader at the US Department of Agriculture’s Bee Research Laboratory in Maryland Dr Jeff Pettis said pesticides, along with poor nutrition and pathogens, were also a problem.

There has been particular concern is recent years about the use of systemic pesticides called neonicotinoids. It is claimed these can enter every part of the plant, including the pollen and nectar and means bees and other pollinating insects can pick them up, even if they are not the target species for the pesticide.

He said: “We call them the three Ps. If we have all three of them present in bees then they will be in poor health, but even having two of them could be problematic.”
Bees contribute up to £200 million to the agricultural economy every year, mainly through crop pollination and honey production.

Scientists have been looking at ways to stem the deaths and researchers have conducted various tests in order to identify the probable causes of colony collapse disorder (CCD).

Dr Pettis said nosema, the parasite which affects the stomachs of honey bees, was ‘very wide spread’ and was ‘always present’.

Other parasites such as the varroa destructor, which spreads dangerous viruses, were also highlighted.

But Dr Pettis said it was a combination of the ‘three Ps’ which amounted to the massive decline in bee numbers.

In addition, the study showed bees had found a way of shielding themselves from diseased cells which the foraging or ‘working’ bees had picked up in the fields.

Colony studies showed the bees had used propolis - a glue-like substance which they use to seal up cracks in the hive - to protect themselves from certain chemicals.