Thursday, April 12, 2012

Imidacloprid linked to bee colony collapse

Harvard scientists recently tested the effects of the pesticide imidacloprid on bee colonies in situ, meaning out in the field instead of in a laboratory.  At each site, four hives were treated with four different amounts of the pesticide.  Beginning with the hives that received the highest doses, and continuing to the hives that received low doses, the bees died in a fashion symptomatic of colony collapse disorder (CCD).

Reactions: The scientists say their findings show that even low doses of imdacloprid, similar to those used in real agriculture, can cause CCD.  The pesticide's manufacturer, Bayer, says the low doses used in the study remained too high to be realistic.  The EPA still considers CCD to result from a mix of factors, possibly including pesticide exposure as just one factor.  That may still be a reasonable summary of the balance of current evidence, but the new study strengthens the case that pesticides -- imidacloprid in particular -- have a big role.

I follow this issue in part because my father-in-law is a retired scientist and a beekeeper.  He tracked the decline and later half-hearted recovery of his hives in lab notebooks.  In 2010, when I took a cross-country drive, visiting sites of food and agricultural interest all along the way, my starting point was his hives in Carlisle, MA.  After reading the Boston Globe article on the recent Harvard Study, he wrote a letter to the editor, which was published this week:
ONE THING we can all do is to put pressure on our elected leaders to have the Environmental Protection Agency do a better job of regulation (“Study links pesticide to bee deaths; Harvard scientists make case,’’ Metro, April 6).

The EPA does not test for the low-level chronic effects of pesticides such as those addressed in the recent studies. It also does not test for interactions between pesticides and other agricultural chemicals - and yet it is known that there are powerful synergies between some of these chemicals.

Furthermore, the EPA farms out its testing to the very companies that are producing the pesticides - kind of like the fox guarding the chicken coop.


e2huber said...

Bayer is correct in their criticism of the Harvard study when they say that the imidacloprid levels were unreasonably high. The study should have started at 20 parts per Billion and gone down to lower levels not up. Recent testing in many areas in the U.S., both agricultural and rural, has indicated that it is much more common for bees to be gathering pollen and nectar with neonicotinoid contamination in the1-2 ppB range than in the 20-400 ppB range such as were used in the study. There have been several important studies at these lower levels, however. The high level contaminations used in this study are encountered only in special situations- like hives near a cornfield using coated seeds. Many beekeepers will no longer place hives near corn fields since 99+ percent of all corn seeds are now coated with neonicotinoids.

rjs said...

it's not much of a surprise that bees would succumb to larger doses of an insecticide...though i'd just as soon see them ban neonicotinids and the rest of the pesticides, i'm not willing to put colony collapse into the solved column on those results yet...i did a lot of reading on CCD when it first broke (subscribed to 2 bee journals back then) and i havent seen anything that fits all the cases reported in those early years..i still think that Israeli acute paralysis virus, first discovered in 2004, is one of several underlying factors, probably weakening the bees to succumb to other issues, such as varroa mites or pesticides...

the only colony i ever lost to CCD symptoms was last april, & it was so wet at the time there wasnt a piece of farm equipment out in the fields anywhere in this county - so no one was using pesticides at that time (im in a wildlife area where there is little ag activity anyhow)

i think some reported CCD is likely normal winter kill, and i know there's also been a lot of CCD in non agricultural areas, too...i'm interested to see how the bees make it this year; mine here in ohio are as strong as they've ever willing to bet that with this warm spring in the east, CCD will almost disappear..