Super insecticide imidacloprid has dramatic impact on insect richness in and around water

Press release Utrecht University - May 2, 2013
Insect numbers have been declining in recent years. Research by Utrecht University has found a link between the super insecticide imidacloprid and a decline in abundance of insects and other invertebrates in surface-water. Scientists are ringing international alarm bells. “Stricter standards alone are not enough. This insecticide is so harmful and remains in the environment for so long that an international ban is definitely warranted.”

Insecticide impacts on surface waters
In just over ten years, imidacloprid has become the most widely used insecticide in the world. Some 20,000 tons are produced annually and used on agricultural land and gardens to combat pests and insects that transmit plant diseases. However, the insecticide is used so widely, leaches so easily and is so poisonous and broad-acting that its lethal effect is not restricted to pests in fields and gardens. Research by Utrecht University’s Copernicus Institute of Sustainable Development has found the use of imidacloprid to have a highly adverse impact on insect abundance in and around surface waters.

Smartly combining monitoring data
Utrecht University scientists were the first to combine two long-term sets of monitoring data in a smart way to study the impact of imidacloprid on aquatic life in Dutch surface-water. As Jeroen van der Sluijs explains, “We see a strong link between situations in which imidacloprid levels in surface water exceed the standards and reduced abundance of aquatic insects.” The pesticide was found to have adverse effects on surface-water ecosystems. The concentration of imidacloprid in the water was too high in almost half the sites monitored in the Netherlands in the past eight years. “On average we found three times less invertebrates in these locations than in water that meets the standard.”

International ban
The ecological impacts of imidacloprid have led to wide-ranging debates in many other European countries, as well as in the US and Japan, where a possible ban on neonicotiniode insecticides is being discussed. Europe decided earlier this week to restrict its use in crops attractive to bees. As Van der Sluijs explains, “We hope that the clear and convincing evidence that our study provides promotes the insight that this far too broad-acting poison is severely affecting our planet’s insect wealth. We are risking far too much to combat a few insect pests that might threaten agriculture. That is why this substance should be phased out internationally as soon as possible.”

The paper written by Tessa van Dijk, Marja van Staalduinen and Jeroen van der Sluijs on their research has been published in PLOS ONE. The research was financed by a grant from the Triodos Foundation, which has set up a special fund for independent research on this controversial group of insecticides.

More information
Jeroen van der Sluijs
Powerpoint presentation of key findings
Read the PLOS ONE article online