A few years back mt expressed skepticism about the connection between pesticides and bee colony disorder. Stronger evidence is in, however.
Youris.com reports that ban on the insecticide-soaked seed coating enforced by the Italian government last year seems to have worked wonders, judging from the freshest data collected on the ground by researchers, beekeepers and regional authorities alike.
Francesco Panella, President of the Italian Association of Beekepers, says:
On behalf of beegrowers working in a countryside dominated by maize crops, I wrote to the Minister of Agriculture to confirm the great news, for once: thanks to the suspension of the bee-killing seed coating, the hives in the Po Valley are flourishing again. We cannot underestimate that there are over one million hectares of maize crops, predominantly in Northern Italy, which means one crop out of every seven which are grown every year in our country. This year’s magnificent and unusual spring growth of bee colonies means a very good production of acacia honey in Northern Italy. We are now anxious to ensure that the temporary ban of neonicotinoid seed coating becomes definitive
Marco Lodesani, director of the honey bee and silkworm unit at the Agricultural Research Council (CRA-API) in Bologna, elaborates:
What did we learn in the past few years about the causes of CCD and the link with neonicotinoids?
Until recently, studies focused on the immediate, lethal effects of pesticides on bees. In other words, they looked at the dose that is needed to kill bees if they are exposed to a certain insecticide.
However, it is now clear that sub-lethal doses have a chronic effect that may be even more critical. When bees fly over the dust from coated seeds, they accumulate small doses of neonicotinoids that do not kill them. But it affects both each individual and the colonies in more subtle, long-term ways. For example, contaminated bees have a weaker immune response. This makes them more susceptible to viruses, which are a major cause of death.
Other effects are neurological and include learning problems, impaired orientation, or the inability to remember colours and odours. All of these aspects are crucial for the social organisation of colonies.
Are these chronic effect taken into account by the industry when testing for the safety of new compounds?
Not really. Testing is largely based on assays that look at the acute toxicity of compounds. But with CCD you do not necessarily expect to see bees decimated right in places where they use pesticides. You need to look at sub-lethal effects that are more insidious and difficult to study, but still involve entire colonies.
UPDATE: The work appears in three white papers released last January. There does not appear to be a peer reviewed version as yet. The white papers are one each on clothiandin, imidacloprid, and thiomethoxam.
h/t to users LooseCannon and super_cookies at Reddit for demanding more information. (That’s all I got.)