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Flying in the face of climate change

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In 75 years’ time, the UK could be plagued by fly populations 250% up on today’s levels if forecasts of climate change prove accurate, ecologists have warned. Writing in a special climate change issue of the British Ecological Society’s Journal of Applied Ecology, Dave Goulson and colleagues from the University of Southampton found that if the worst case scenario for climate change occurs - a 5 deg C rise in temperature by 2080 - house fly numbers in the UK could explode.

Studies on the ecological impact of climate change has to date largely focused on butterflies and birds, two groups for which data on distribution and abundance abounds. Until now, ecologists have been less keen to study flies, but says Dr Goulson: “The annoyance and public health risks associated with large populations of flies are considerable, and potential increases in their abundance as a result of climate change are a cause for concern.”

Between January 2000 and December 2003 Dr Goulson and his colleagues monitored populations of calyptrate fly species - including the house fly Musca domestica and bluebottles Calliphora spp. - at six sites in Hampshire, three of which were near landfill sites. Over the four years they set almost 10,000 yellow sticky traps and caught more than 100,000 calyptrate flies.

Using the first three years’ data for weekly fly catches and prevailing weather conditions (temperature, rainfall and humidity) Dr Goulson constructed a model of the relationship between weather and fly populations. He then tested the model’s predictions against the actual number of flies caught in the fourth year of the study.

According to Dr Goulson: “Our study demonstrates that calyptrate flies are likely to be among the species that respond positively to a warming climate: population fluctuations were strongly determined by weather and we predict that small increases in temperature can lead to major increases in fly density.”

The results are important because they show how climate change could impact on disease in the UK. The adults of many species of calyptrate flies feed on human food as well as refuse and excrement and therefore act as important disease vectors. Up to 10 million flies can emerge from just 1 ha of household waste.

Dr Goulson’s findings could also mean that fewer pesticides need to be sprayed on landfill sites to control fly populations in future. “We successfully predicted M. domestica numbers from simple and readily recorded weather variables. This could be used to limit prophylactic spraying to periods when climatic conditions are likely to favour fly population increases,” he says.

Other papers in the special climate change issue of the Journal of Applied Ecology include:

* The British Ecological Society lecture on climate change: the science and the policy, given by Professor Sir David King at last year’s BES annual meeting.

* Recommendations by Norman Ratcliffe and colleagues from the RSPB on how best to conserve UK populations of the Red Listed black-tailed godwit. The birds are restricted to a handful of sites in England, two of which - the Ouse and Nene Washes - are floodwater storage structures protecting local property and farmland against flooding. However, if these areas flood in spring, the nesting godwits suffer and Dr Ratcliffe’s modelling suggests that to conserve the godwits, habitats need to be created outside the flood areas.

* Changes should be made to the way forests are managed, in order to reduce the increasing risk of forest fire as a result of climate change. Research by Allison Cocke and colleagues from Northern Arizona University shows that fire suppression management of forests on the San Francisco Peaks in Arizona has substantially increased the risk of devastating fires in these ecosystems.

While evidence mounts for the impacts of climate change on biodiversity, this special issue of the Journal of Applied Ecology illustrates the need for more research into how best to cope with climate change. According to the journal’s editorial by Dr Philip Hulme of the Centre for Ecology and Hydrology in Banchory: “While climate change impacts may be severe, they are often exacerbated by current management practices, such as the construction of sea defences, flood management and fire exclusion. In many cases, adaptation approaches geared to safeguard economic interests run contrary to options for biodiversity conservation.”

“There is a need to ensure that environmental and conservation policies not only address climate change but are sufficiently flexible to respond to rapid ecosystem alteration. Awareness among policy makers is increasing and hopefully further catastrophes will not be required to catalyse global efforts,” Hulme says.

Becky Allen | Quelle: alphagalileo
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