Bees can't sniff out flowers because of CARS: Diesel fumes change the odour of blooms and could cause a global food crisis Scientists from the University of Southampton said honeybees use floral odours to find flowers that will give the best yields of pollen and nectar Harming the forager bees' ability to find the flowers from which they get pollen and nectar is likely to damage the success of the colony or hive Researchers focused on diesel as they were also interested in the impact on bee foraging of particulates, known to harm human health Diesel pollution makes it harder for honeybees to find flowers by changing the chemical make-up of their scent, scientists have found Diesel pollution makes it harder for honeybees to find flowers by changing the chemical make-up of their scent, scientists have found. Honeybees use floral odours to find flowers that will give the best yields of pollen and nectar but diesel fumes can affect their ability to locate and recognise the plants, potentially affecting pollination and ultimately global food security. British researchers took eight chemicals found in the odour of oilseed rape flowers and mixed them both with clean air, which had no impact on the scent, and air containing diesel fumes. When mixed with diesel fumes, six of the eight chemicals reduced in volume and two disappeared completely within a minute, changing the chemical mix of the scent as it reacted with nitrogen oxides (NOx) found in the exhaust fumes. The researchers, from the University of Southampton then trained honeybees to recognise a synthetic oilseed rape perfume, by giving the bees a sugar solution when they were exposed to the scent so that they learned to stick out their proboscis when they smelled it. When they were exposed to a synthetic floral odour which had the chemicals affected by nitrogen oxides removed, the proportion of honeybees able to recognise the scent was significantly reduced, the study published in the journal Scientific Reports found. The researchers said the number of bees recognising the odour fell from 100 per cent to 30 per cent when both the chemicals affected by nitrogen oxides were taken out of the scent. Dr Tracey Newman, a neuroscientist at the university, said: 'Diesel exposure alters floral odours and it's a significant enough change in the chemistry to impact on the honeybee's ability to recognise that odour. Honeybees use floral odours to find flowers that will give the best yields of pollen and nectar but diesel fumes (pictured) can affect their ability to locate and recognise the plants, potentially affecting pollination and ultimately global food security The honeybee (Apis mellifera) is a social bee that forms large colonies. A strong honeybee colony may contain about 60,000 bees. Several factors have been identified as probable contributory causes of honeybee decline: The Varroa mite sucks bee blood from the bodies of honeybee larvae, pupae and adult bees in hives around Britain. Infested colonies can die within two or three years. Honeybees and their larvae are affected by many diseases caused by bacteria, fungi and viruses. Research has shown a link between certain bee viruses and colony decline. As honeybees need more care and management to watch levels of Varroa mites, neglect by beekeepers can kill colonies. Pesticides are blamed for bee losses and insecticides are sprayed directly onto the creatures. Particular concern has been raised about some neonicotinoid insecticides, which are used by farmers and gardeners to control a wide range of pests. 'It's not just about a bee getting confused because there's a new smell around, it's that the odour itself is being chemically altered.' The scientists focused on diesel because they were also interested in the impact on bee foraging of particulates (PMs), which are known to harm human health and are found in much higher levels in diesel. But as nitrogen oxides - nitrogen dioxide and nitric oxide - are also found in petrol fumes the pollution from much of road transport could be having an effect, they said. Harming the forager bees' ability to find the flowers from which they get pollen and nectar is likely to damage the success of the colony or hive, affecting the number of colonies and the pollination of crops that are important to humans. Professor Guy Poppy, ecologist at the University of Southampton, said: 'Honeybee pollination can significantly increase the yield of crops and they are vital to the world's economy - £430 million a year to the UK alone. Dr Tracey Newman, of the university, said: 'Diesel exposure alters floral odours and it's a significant enough change in the chemistry to impact on the honeybee's ability to recognise that odour' However to forage effectively they need to be able to learn and recognise the plants. The results indicated that NOx gases, particularly nitrogen dioxide, may be capable of disrupting the odour recognition process that honeybees rely on for locating floral food resources. The scientists said air pollution could be one of a number of stresses that could be harming honeybees which, like many pollinating insects, are struggling. Dr Newman said: 'Diesel exposure is not the root of the problem in honeybees. However if you think of a situation where they're dealing with vial infections, mite infections, another thing that then makes it harder in its environment adds to the list of stresses. 'It is likely to have detrimental consequences for the animals' health.' Dr Giles Budge of the Food and Environment Research Agency, said the researchers have pinpointed 'a fresh issue to add to the many problems facing our insect pollinators, the potential for the fumes from a generator to degrade flower scent. This work highlights a possible problem in a laboratory setting and the challenge will be to see whether this problem exists in the wider environment.