Neonicotinoid pesticides have been proposed as the most likely cause of collapsing bee populations, although the claim remains very much disputed. Now the Worldwide Integrated Assessment report has concluded the damage extends to worms and butterflies, and even fish and birds. Unsurprisingly, the authors have called for tighter regulation of the their use.
Although none of the other species thought to be affected by the use of the neurotoxins have anything like the commercial importance of bees, the alleged impact on vertebrates raises questions about whether humans might also be vulnerable. The report expresses similar concerns about fipronil, a different soft of neurotoxin insecticide.
Neonicotinoids are used to treat seeds prior to planting. Advocates say the targeted methodology means application doses are low and protection long-lasting. The main manufacturers, Bayer and Snygenta, predict losses in the billions of dollars from bans on the products.
However, if the decline in bee populations globally is not reversed the losses will be far larger. Insect pollinators, predominantly bees, were estimated to be worth €153 billion in 2005, and mass starvation is very likely if their decline cannot be halted.
The question of whether neonicotenoids are responsible is thus a matter of enormous significance. Most scientists agree that there must be multiple factors causing bees to suddenly desert their hives, but whether neonicotenoids are one of the major ones remains hugely controversial. Several studies claim to demonstrate a link, but their relevance or sample size has been questioned.
The European Union has implemented a two year trial ban on the basis that, while the evidence was not conclusive it was strong enough to justify action.
The Assessment, conducted on behalf of the International Union for the Conservation of Nature and to be published in Environment Science and Pollution Research has widened the focus. Reviewing 800 studies it found that leaching into the soil is affecting earthworms, upon which the long term health of the soil depends, even more severely than bees. However, some studies report the damage goes further, reaching into waterways and affecting birds that eat fruits grown from treated seeds or insects that have fed on the plants.
“The evidence is very clear. We are witnessing a threat to the productivity of our natural and farmed environment equivalent to that posed by organophosphates or DDT. Far from protecting food production the use of neonics is threatening the very infrastructure which enables it, imperiling the pollinators, habitat engineers and natural pest controllers at the heart of a functioning ecosystem,”said Dr Jean-Marc Bonmartin, of the French National Center for Scientific Research, one of the reports lead authors.
Crop Protection Association chief executive Nick von Westenholz hit back, calling the report, "A selective review of existing studies which highlighted worst-case scenarios, largely produced under laboratory conditions".