Wetenschap - 8 juli 2010

Who’s going to watch out for bugs now?

The Ministry of Agriculture, Nature and Food Quality (LNV) plans to end funding for the ‘Invasions, diseases and plagues’ project. This will probably put an end to a biological dataset that is 65 years old. ‘Stopping this project is asking for trouble. For 65 thousand euros you can buy your way out of a lot of problems.’

There is no mistaking insect plague expert Leen Moraal's office at Alterra for anything but the habitat of an entomologist. There are glass jars full of pale, lifeless larvae dotted about amongst the countless stems and branches knawed on by insects. Moraal works on insects that thrive on live and dead wood, and specializes in plague insects. He picks up a barkless bit of trunk and points out a network of corridors bored into the wood. 'This is the work of the emerald ash borer', he explains. 'The mother makes the main entrance and lays eggs at regular intervals as she bores her way in. When the larvae hatch out they make the narrower passaged going off from the main one.' It looks rather beautiful, but it is bad news for the tree: tens of thousands of knawing larvae usually spell its downfall. 'The mother beetle can only do this in a weakened tree', says Moraal. 'Healthy trees encapsulate the eggs by forming callouses around them.'
Early warning
Moraal is the key resource person on insect plagues in the Netherlands. Since 1946, infestations on trees and shrubs have been monitored and reported by a network of hundreds of volunteers. 'You have to keep that network alive', says Moraal, 'It works well because we are a free service. People can send us insects or photos of insects and we will identify them.'
Moraal thinks it is very important for new plagues to be picked up early. Goods transportation has increased enormously over the past fifty years, and that raises the risks of unwelcome six-legged stowaways, hiding in wooden packing material for example. The entomologist fears for an invasion by the Asian emerald ash borer, which reached North America in packing material and has caused havoc there, killing 30 million ash trees in the US and Canada. 'If this creature comes to Europe and we don't notice it in time, we'll lose all our ashes', claims Moraal. 'With early warning of a new plague like that, you might be able to do something about it.'
The ending of the subsidy for monitoring plagues has many negative consequences. 'Things like dehydration, the increasing nitrogen levels and climate change affect the vitality of trees and therefore favour plague insects which depend on weakened trees', says Moraal. 'In the case of the oak processionary caterpillar, for example, we know that populations now regularly reach plague proportions due to global warming.'
By keeping managers and the public informed about plagues - usually through the media - you put people more at ease, says Moraal. People might come to understand that one tree that has been stripped bare is not necessarily a disaster. 'With the knowledge that we have collected over the decades, we can predict which plagues are likely to crop up, what causes them and what could be done about them', he explains. Climate scientists are predicting drier summers, for example. Rising drought stress will lead to larger numbers of weakened trees that are vulnerable to plague insects. Moraal: 'We had a taster of the effects of a dry summer in 2003, when the oak processionary caterpillar made a killing because the oaks were all weakened by drought. In the end, four percent of the Dutch oaks died.'
Professor of applied animal ecology Henk Siepel is not happy about the funding being cut. 'Incomprehensible and a great pity if this is ended', he says. 'If there is one project that delivers the goods, it is this one.' Siepel is particularly shocked by the reasons given for stopping the subsidy: ' "The project cannot be relevant because it has been going so long." That was literally how it was put.' Siepel thinks a timescale of 65 years is unique in the Netherlands and very relevant for recognizing patterns and changes and preventing plagues in the country. Some plagues have disappeared while others are rearing their heads. 'The project is not just about monitoring and collecting knowledge. It is also a helpdesk where people can come with their questions.' The researchers also use the information they collect to advise nature managers on which trees they should or should not plant.
However, for the ministry of LNV, this project does not have priority. 'We have got to make budget cuts in the knowledge business too. We have got to be more and more critical about how we use scarce means', says Jan Willem van der Ham, policymaker at the department of Nature, Landscape and Rural Areas. 'We've got to set priorities.'
Oak processionary caterpillar
The data this project provides can be the starting point for further research, says Siepel. For example, on the basis of the dataset, researchers established that plagues of insects that are not very mobile, such as the oak processionary caterpillar, increased threefold between 1945 and 2005. Siepel: 'If you look at photos from then and now, you see that the landscape has changed enormously. By planting trees along the roads and lanes everywhere, we have solved the mobility problem for this group of insects. Against our will, we have played into the hand of these plagues.'
Siepel calls the funding cut 'penny wise, pound foolish'. 'For 65 thousand euros you can buy your way out of a lot of problems, and it is of real scientific importance too', says the professor. 'You will get a lot of hassle and unease if the helpdesk isn't there any more. Then there is no one who can tell you within five minutes over the radio whether or not there is a real problem.' In spite of the poor outlook, Siepel will go on standing up for the plague network. 'Over the past few years, we have already snatched the project from the jaws of death a couple of time. Nothing is certain until the curtain falls.'