Is there a link between the insecticide imidacloprid and the dwindling bird population in the Netherlands? An alarming claim that there is got Nijmegen researchers in the news recently.
Is the substance that is blamed for bee deaths fatal to birds as well? This conclusion is premature, according to professor of Chemical Stress Ecology Paul van den Brink.
What are the shortcomings of the study?
‘First of all, it only looked at imidacloprid. It would be much stronger if it had included other insecticides as well. And secondly, it only looked at insect-eating birds. As a control group you could make a comparison with birds which are not dependent on insects. The perfectly plausible assumption is that imidacloprid kills insects, leaving birds with not enough to eat. So you take two steps in one correlation.’
That is a fundamental criticism. How does a study like this get into Nature?
‘That amazes me too. The researchers could have done their work much better.’
What is the value of this study?
‘This study shows me that there is a relation between imidacloprid and the reduction in numbers of some birds. The study also shows that we need to look much better at the effects of imidacloprid on insects which are not the target. Imidacloprid is a persistent substance. In our lab studies you see that in the long term imidacloprid has effects even in low concentrations. So much more data need to be collected about the chronic effects on insects in water and in the air.’
What does the future look like for imidacloprid?
‘Based on our study last year on the effect of imidacloprid on aquatic life, a couple of uses of imidacloprid in the Netherlands have been banned. In Germany the norms have even been made much stricter. If Europe follows, the neonicotinoids are in deep trouble. It is quite funny really: while everyone is bickering about the effect of imidacloprid on bees, the substance might go out of use because of its effects on aquatic life.’