22 June 2010

Impairment of brain function may hold clue to decline of bee numbers

Researchers from the University of Dundee have been awarded funding of £1.8million to examine whether the use of pesticides is hampering the cognitive functions of bees - and possibly hastening their demise.

The multidisciplinary project, led by Dr Chris Connolly and Dr Jenni Harvey from the University’s Centre for Neuroscience, will examine whether chronic exposure to a combination of chemicals could be harming bumblebees and honeybees, whose decline in number has attracted worldwide coverage over the past few years.

It is one of nine projects to share in a £10million funding package announced today as part of National Insect Week. The funding is provided by the Insect Pollinators Initiative, which aims to explore the causes and consequences of threats to insect pollinators, ensure that the pollination of agricultural and horticultural crops is protected and that biodiversity in natural ecosystems is maintained.

The Dundee team will investigate the 'synergistic impact of sublethal exposure to industrial chemicals on the learning capacity and performance of bees brains'. While pesticides are screened to be non-lethal to bees before they are passed for use, Dr Connolly said the Dundee team will examine whether a combination of chemicals used in agriculture may cause unexpected damage to bees.

'Many insecticides work by interfering with information flow in the brains of insects - either increasing or decreasing their brain activity,' he said. 'We will be looking at whether chronic exposure to chemicals used to control mites, combined with levels of agricultural pesticides that are not themselves lethal , may act together to magnify their affects on bee brain function.'

In collaboration with Dr Geraldine Wright (University of Newcastle) and Dr Nigel Raine (Royal Holloway, London) they will investigate the potential damaging effects of such agents on bee performance in learning visual and olfactory skills, foraging, navigation and communication.

'We rely on a varied cocktail of pesticides to protect our food supply and homes from pest damage,' continued Dr Connolly. 'Pesticides are also used to protect honeybees from mite infestation. Exposure to such chemicals could also be harming other beneficial pollinators and chronic exposure may be particularly important in the context of other challenges faced by these insects. Such effects may have a serious impact on biodiversity.

'It is believed that pesticides, when present in isolation, at the levels thought to exist in the environment, do not kill bees. Our hypothesis is that these chemicals may have a synergistic effect on the brain function of bees.

'Problems may manifest at a number of behavioural levels: Navigation (finding their way to food or returning home), communication (passing information regarding food supplies) and learning/memory (failure to remember food sources). In addition, developmental consequences may affect bee maturity and cognitive abilities.

'If bees were to die out, then our food security would be seriously compromised. We rely exclusively on bees to pollinate such a large number of our staple foods and the only alternative, which is hand pollination, is not really an option.'

The number of bees in the UK fell by up to 15 per cent in the two years up to April 2009, while the population of butterflies and other insects is also down. Declining numbers of bees are particularly concerning as it is believed up to a third of human nutrition is dependant on bee pollination and the total loss of insect pollinators could cost up to £440million per year in the UK alone.

No single cause for pollinator decline has been identified, and the reasons behind it are thought to be complex and involve interactions between the pollinator, the environment and the pests/diseases that affect these insects. Because of the vital role pollinating insects play, it is absolutely crucial that research is carried out to try and reverse the decline.

The projects will look at different aspects of the decline of insect pollinators. Some will focus on specific species and/or diseases; others will look more broadly at factors affecting the health and survival of some or all pollinating insects. The initiative brings together researchers from many disciplines including ecology, molecular biology, mathematics, and computing.

Dr Connolly and Dr Harvey’s research usually focuses on the neuronal communication in the mammal brain, but Dr Connolly said the pollinator decline crisis was of such importance that their skills, when aligned with those of existing bee experts, could be helpful in examining the insect world. Moreover bees, along with ants and wasps, are unusual - not just amongst insects, but mammals too - in that they live in a complex society. As such, they may provide a novel model system to study social learning.

The Dundee scientists will work closely with colleagues at Royal Holloway Hospital, the University of Newcastle and University College London as part of the research.

They will monitor honeybees and bumblebees and investigate their ability to learn different visual and olfactory tasks. In addition, they will assess their performance using the radio tagging of individual bees. Finally, the group will attempt to develop the first honeybee cell line for use in the screening of future pesticides and miticides.

In partnership with the Scottish Beekeepers Association they will carry out a three year survey to correlate the impact of environmental chemicals to colony performance and investigate if patterns of environmental risk factors support the laboratory data.

In summary, this project will be seeking to understand the molecular basis of learning and memory in bees using our knowledge of mammalian processes and address if, and how, these are affected by pesticide exposure.

'If synergetic effects are discovered to impair the brain function of bees, this information may influence the coordination of pesticide use. Moreover, we must then also look at whether the combination of these chemicals has the same effect on humans,' added Dr Connolly. 'Although pesticides are designed not to work on humans, synergistic interactions may amplify toxicity as much as 1000-fold.'

NOTES TO EDITORS

The Insect Pollinators Initiative is a joint scheme involving the Biotechnology and Biological Sciences Research Council, the Department for Environment, Food and Rural Affairs, the Natural Environment Research Council, the Scottish Government and the Wellcome Trust, and is funded under the auspices of the Living With Environmental Change partnership.

Projects funded under the initiative are:

• Sustainable pollination services for UK crops - Dr Koos Biesmeijer, University of Leeds.
• Modelling systems for managing bee disease: the epidemiology of European Foulbrood - Dr Giles Budge, Food & Environment Research Agency.
• Investigating the impact of habitat structure on queen and worker bumblebees in the field - Dr Claire Carvell, NERC Centre for Ecology and Hydrology.
• An investigation into the synergistic impact of sublethal exposure to industrial chemicals on the learning capacity and performance of bees - Dr Chris Connolly, University of Dundee.
• Linking agriculture and land use change to pollinator populations - Professor Bill Kunin, University of Leeds.
• Urban pollinators: their ecology and conservation - Professor Jane Memmott, University of Bristol.
• Impact and mitigation of emergent diseases on major UK insect pollinators - Dr Robert Paxton, Queen's University of Belfast.
• Unravelling the impact of the mite Varroa destructor on the interaction between the honeybee and its viruses - Dr Eugene Ryabov, University of Warwick.
• Can bees meet their nutritional needs in the current UK landscape? - Dr Geraldine Wright, Newcastle University.

More information is available at www.bbsrc.ac.uk/pollinators.

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Grant Hill
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University of Dundee
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