Pesticides contributing to decline in bee numbers

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.

Readers' comments (4)

  • I accept that neonicotinoids have the potential for affecting bees through uptake in pollen, but why are bees declining in countries such as France, which has effectively banned neonicotinoids from flowering crops such as oilseed rape, sunflowers and maize? These products are only used on sugar beet which does not flower and is not visited by bees. The evidence of neonicotinoid poisoning is scant from what I have seen in the literature.

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  • Some neonicotinoids have been banned on sunflowers and maize, whilst others have not. This means one neonic has been replaced with another, or Fipronil, another systemic toxin.
    There is no blanket ban on all neonicotinoids for all crops, or even groups of crops.

    This is why French beekeepers are rightly upset, and continue in their protest.

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  • If AW is correct and neonicotinoid use continues as it has, why have bee losses over the last two years in the UK fallen to their lowest in ten years?

    Dr Pettis is correct in stating that neonicotinoid use is a factor BUT only a factor and in itself would probably do no harm to the bees. We should encourage improved bee health (through registration on BeeBase) which lets Bee Inspectors check the all hives. In addition we should increase beekeepers awareness of hive hygiene to try to eradicate the varroa mite. We would then probably see even greater declines in bee losses.

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  • If I communictaed I could thank you enough for this, I'd be lying.

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