The Moth versus the Crowd - Tracking an alien invader of conker trees using people power

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Publication of new scientific paper a demonstration of how seriously citizen science is now taken by the community of professional scientists

An army of citizen scientists has helped the professionals understand how a tiny ‘alien’ moth is attacking the UK’s conker (horse-chestnut) trees, and showed that naturally-occurring pest controlling wasps are not able to restrict the moth’s impact.

The study’s conclusions are published this week in the open access scientific journal PLOS ONE.

No bigger than a grain of rice, the horse-chestnut leaf-mining moth has spread rapidly through England and Wales since its arrival in London in 2002. The caterpillars of the moth ‘tunnel’ through the leaves of conker trees, causing them to turn brown and autumnal in appearance, even in the height of summer.

In 2010 thousands of ‘citizen scientists’ were asked by two professional ecologists to collect records of leaf damage from across the country as part of a project called ‘Conker Tree Science’.

The results show that over the last decade the moth has spread from London to reach almost all of England and Wales. Investigating the data further the scientific team concluded that it takes just three years from the first sighting of the moth in a particular location to maximum levels of damage to the horse-chestnut trees being recorded.

In a follow-up experiment, many of the citizen scientists, including hundreds of school children, followed instructions to rear the moth by sealing the infested leaves in plastic bags and waiting for the insects to emerge. The results reveal that the tiny pest controllers (‘parasitiod’ wasps) that prey upon the caterpillars are not present in high enough numbers to control the moths.

Dr Michael Pocock, an ecologist at the Centre for Ecology & Hydrology and lead author of the research paper said, “This is the sort of science that anyone can do. By taking part the public are doing real science – and the publication of this scientific paper is a demonstration of how seriously citizen science is now taken by the community of professional scientists.”

Co-author Dr Darren Evans, a conservation biologist at the University of Hull said, “This work could have been done by paying research assistants to travel the country and collect records, but by inviting thousands of people to get involved we, together, were able to pull this off much more cost-effectively.”

Dr Pocock added, “It seems almost like magic for children and other people to put a damaged leaf in a plastic bag, wait two weeks and then see insects – the adult moths or their pest controllers – emerge, but making these discoveries was a valuable contribution to understanding why some animals become so invasive.”

Dr Evans added, “We have been challenged by other professional scientists as to whether ‘ordinary people’ can make accurate observations, suitable for real science. Of course they can – and we tested this in our study. So thank you to the thousands of participants because together we were able to do this science.”

Unlike some other citizen science projects that use biological records submitted by members of the public for long-term monitoring, the Conker Tree Science project set out to test two specific hypotheses over the course of a year. The authors suggest that this approach can be developed to examine a range of environmental problems.

Conker Tree Science was run with funding from the Natural Environment Research Council and begun when the two authors were at the University of Bristol.

Barnaby Smith, Media Relations Manager, Centre for Ecology & Hydrology

Tel: 44 (0)7920 295384 Email: bpgs@ceh.ac.uk

Centre for Ecology & Hydrology Maclean Building, Benson Lane Crowmarsh Gifford, Wallingford Oxfordshire, OX10 8BB

The Centre for Ecology & Hydrology (CEH) is the UK's Centre of Excellence for integrated research in the land and freshwater ecosystems and their interaction with the atmosphere. CEH is part of the Natural Environment Research Council, employs more than 450 people at four major sites in England, Scotland and Wales, hosts over 150 PhD students, and has an overall budget of about £35m. CEH tackles complex environmental challenges to deliver practicable solutions so that future generations can benefit from a rich and healthy environment. You can follow the latest developments in CEH research via Twitter www.twitter.com/CEHScienceNews and our rss news feed http://www.ceh.ac.uk/rss/rss.xml

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Quick facts

Since 2002, the moth has spread from London to reach almost all of England and Wales
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The scientific team concluded that it takes just three years from the first sighting of the moth in a particular location to maximum levels of damage to the horse-chestnut trees being recorded
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Quotes

This is the sort of science that anyone can do. By taking part the public are doing real science – and the publication of this scientific paper is a demonstration of how seriously citizen science is now taken by the community of professional scientists.
Dr Michael Pocock, CEH
We have been challenged by other professional scientists as to whether ‘ordinary people’ can make accurate observations, suitable for real science. Of course they can – and we tested this in our study.
Dr Darren Evans, University of Hull