Organisatie - 8 maart 2012

Study exonerates imidacloprid bee poison

There is no evidence that insecticides such as imidacloprid are responsible for the mass bee deaths, concludes an international group of researchers headed by Wageningen bee expert Tjeerd Blacquière.

He carried out a review for the Ministry of Agriculture on the effect of neonicotinoids on bees. The group investigated all the available scientific articles for the past fifteen years - the period in which neonicotinoids have been used.
‘They show there is not much evidence that these chemicals are playing a big role in bee deaths', says Blacquière emphatically. ‘Neonicotinoids are an effective, useful insecticide. That conclusion still stands.' This does not mean these chemicals are not poisonous. ‘They are incredibly toxic to bees, which is not surprising given that they are insecticides. And imidacloprid is the most toxic of them all.'
Room for improvement
But Blacquiere says this toxicity is most evident in lab studies. In practice the damage is not too serious. Studies show that the levels of poison in nectar and pollen are low and not fatal. With the important proviso that there is not much data. ‘Too little is known in the publicly available literature. This is a gap in our knowledge.' One reason is that a lot of data is not publicly available. The Bond for the Authorization of Pesticides in the Netherlands does not publish its data. That is a major disadvantage, says Blacquière, who advocates more openness. ‘The government could force the authorization studies to be peer reviewed and published. That would bring them into the open and would also let you compare those studies with other research, thereby contributing to scientific knowledge.'
Blacquiere also thinks the neonicotinoids could do with some more fine-tuning. ‘There is certainly room for improvement. You could make them more specific, and less long-lasting so that they are broken down more quickly in nature.'

It was a Zembla programme last year that triggered the neonicotinoids review. It put Wageningen's bee research in a bad light, saying Blacquiere was trivializing the role of imidacloprid for the sake of the pesticide industry. ‘It made quite a dent in my reputation', says Blacquiere laconically. ‘So the results of this study feel like a rehabilitation.' A detailed report based on the review in Ecotoxicology is currently with the Ministry.