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Diesel threat to pollination – study

http://www.iol.co.za/scitech/science/environment/diesel-threat-to-pollination-study-1.1587928

October 7 2013 at 09:47am By Melanie Gosling

Cape Town – One in three mouthfuls of the food we eat depends on bee pollination – but our industrial lifestyles are making it difficult for bees to pollinate crops.

Bee pollination is vital for a wide variety of food crops and is worth £430-million a year to the UK economy alone. In the US, bees help farmers produce crops worth $20-billion to $30bn a year.

Now research by the University of Southampton, published in the journal Scientific Reports, has found that when bees are exposed to air pollutants from diesel exhaust emissions it affects their ability to recognise the scent of flowers.

In this way, diesel pollution could affect global food security, researchers say. Bees use floral odours to help them find and identify the flowers they target to forage for nectar.

To test the impact of diesel exhaust on bees, researchers mixed two lots of rapeseed flower scent, one with clean air and the other with diesel exhaust fumes.

There were eight chemicals in the rapeseed scent. The scent that was mixed with clean air was unaffected.

But when mixed with diesel fumes, six of the eight chemicals in the rapeseed scent reduced in volume, while two disappeared altogether within minutes of mixing.

This showed that the flower scent had been completely changed by the diesel exhaust emissions.

The researchers did the same with nitric oxide and nitrogen dioxide, both found in diesel exhaust, with the same outcome.

The flower scent and diesel mix was then shown to bees, which could not recognise it.

Tracey Newman, a neuroscientist at the university, said this suggested that diesel exhaust pollution altered the the floral odour, which in turn affected the bees’ recognition of flowers.

This could have a serious detrimental affect on both the number of bee colonies and pollination activity.

In May this year, the US Environmental Protection Agency and the Agriculture Department published a report which said the number of bee colonies in the US had more than halved since 1947, largely because of parasites, disease and pesticides.

The decline raised doubts about whether honey bees could fulfil their crucial role in pollinating crops that played a role in about a third of all food and beverages sold in the US. – Cape Times