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February 17, 2012 9:53 pm
Ladybirds are currently a focus of ecological attention, with the publication of two international studies of these much-loved insects.
One provides compelling evidence that the harlequin ladybird, an invasive species introduced to Europe from east Asia, is causing large declines in several native species.
The second study shows that the intensity of a ladybird’s red colour is a direct indicator of how toxic it is to predators. Better fed ladybirds give a more visible warning signal and are more deadly.
Although invasive alien species are widely recognised as a driver of biodiversity loss, there are surprisingly few clear demonstrations in the scientific literature of the impact of a new arrival on native species.
A study, led by the UK Centre for Ecology & Hydrology and Belgium’s Research Institute for Nature and Forest, examined thousands of ladybird distribution records following the harlequin’s arrival in Belgium in 2001 and Britain in 2004. The records were collected mainly by members of the public and verified by experts.
The results, published in the journal Diversity and Distributions, show a steep decline in seven of the eight native species studied in Britain and five of the eight species in Belgium. Worst hit was the two-spot ladybird, now “near the threshold of detection” in habitats where it was previously common.
The harlequin, whose colouring and spotting is much more varied than native European ladybirds, lives in deciduous trees and shrubs. It has a particular impact on species such as the two-spot, which share the same ecological niche – through predation and competition.
One common European species, however, remains unaffected by the harlequin’s arrival: the seven-spot ladybird. The ecologists believe this is because the seven-spot is a large ladybird and therefore able to defend itself against the harlequin – and its preferred habitat, herbaceous vegetation, overlaps less with the harlequin.
The seven-spot is, coincidentally, the subject of the second ladybird study – published in Functional Ecology. Researchers at Exeter, Liverpool and other universities reared seven-spot ladybirds on either a low-quality or a high-quality diet of aphids, their favourite food. The better fed insects had not only redder wings but also higher levels of the toxic chemicals that put birds off eating them.
“Those with less good access to food are less toxic, so they try to copy the brighter, more expensive signals of the more toxic animals that had better access to food,” says Mike Speed of Liverpool.
“However, the well fed animals appear to win the battle as the signals they make are too bright and expensive for the other animals to copy.”
Science’s own financial crisis
Powerful evidence of the financial sector’s failure to stimulate science-based growth has emerged from a €1.5m (£1.25m) research project funded by the European Commission’s Framework programme.
The three-year Finnov project (its name stands for finance innovation) analysed the extent to which the financial system promotes or impedes growth in a range of high-tech and science-based sectors. The results reveal a “dysfunctional” system, which has become worse during the current crisis.
According to researchers at Canada’s Dalhousie University, drivers who have had cannabis within the past three hours are nearly twice as likely to cause a crash as those not under the influence of drugs or alcohol.
“The crisis has exposed deep flaws in conventional economic thinking on which financial policies and regulations have been based,” says Mariana Mazzucato of the University of Sussex, the project leader.
“The changing links between risks and rewards have contributed to an increasing ‘financialisation’ of the economy, and this has allowed parts of the financial services sector to extract value at the expense of industrial growth,” she adds. “This practice is undermining investment in productive activity.”
Finnov debunks what the researchers call a series of myths about the financial system’s role in supporting innovation-led growth. Most importantly, its report says policymakers should reject the myth that markets are the best way to co-ordinate economic activity and “recognise the important role played by the state in supporting and encouraging innovation”.
Government can pick winners, contrary to free market belief, Finnov found. Around the world, state funding has played a key role in launching new sectors.
Another myth is that private venture capital funds drive innovation, according to the report. In fact private VC funds “have performed poorly and now have trouble raising enough money to reach the size needed to be commercially viable.” “Hybrid funds”, with private investment backed by public money, are a more successful VC model, Finnov shows.
How to make sewage disappear
New technology, using superheated water and oxygen, could help dispose of the millions of tonnes of unwanted sewage sludge that is generated every year by the world’s water treatment plants.
AquaCritox, as it is called, was originally developed in the US to destroy military and specialised industrial waste. Since 2007 an Irish company, Supercritical Fluids International (SCFI), has been working to take it into the general sewage treatment market.
Its first commercial-scale plant, under construction at Youghal, County Cork, is scheduled to start up later this year, processing 60 tonnes a day of sludge produced by 140,000 people. The process involves compressing a stream of wet sludge to a high pressure (220 atmospheres) and heating it above 375C. Under these conditions the water enters a new “supercritical” fluid phase and, when oxygen is added, all organic materials in the sludge are oxidised very quickly.
The oxidation reaction produces more water, carbon dioxide (which can easily be captured and sold for industrial use) and, most importantly, energy. This can be used to generate electricity to power the water treatment process or feed into the local grid.
John O’Regan, SCFI chief executive, says the installation costs – from £4m for a system to treat sewage sludge from 40,000 people up to £24m for 1m people – are affordable. “We are currently in discussion with a number of UK water companies,” he says.
Getting dirty could be good for you
The hygiene hypothesis – the idea that you need considerable exposure to dirt and germs early in life if your immune system is to work well – is supported by growing epidemiological evidence. People raised on farms, for example, suffer fewer auto-immune disorders than people who grow up in clean modern cities.
Now research at Bristol University has shown directly that farm life damps down the excessive immune responses that can lead to allergies, inflammatory disease and other health problems – at least in pigs.
The scientists separated six litters of piglets into two groups. Half of the animals were nursed by their mothers on a farm while their siblings were reared in a hygienic isolator unit.
The study, published in the journal Pediatric Allergy and Immunology, found profound differences between the immune systems of the two groups.
In particular the farm-reared animals had many more regulatory T-lymphocytes, cells that pacify immune responses and limit inflammation. These pigs reacted less to novel food proteins after weaning – a sign of reduced susceptibility to allergy.
Marie Lewis, the study leader, says more research is needed to establish what causes the increased capacity for immune regulation in the farm-reared piglets. “Our previous work suggests that intestinal bacteria play a pivotal role in the development of a competent immune system and these bacteria are obtained from the environment during early life,” she adds.
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