Tag Archives: Synergisms

Powerful Poisons Interact to Attack the Industrious Honey Bee

In and of themselves pesticides may not be the sole culprits of Colony Collapse Disorder (CCD).  Could understanding the synergisms between these chemicals help solve the mystery of CCD?

Beeswax Candles--Courtesy of Roberrific/Flickr Creative Commons

The snowstorm is looming. Tom Theobald, Boulder Colorado bee keeper, will retire to his honey house to watch the early winter flakes dance in the cold air.  There, he will be “doing a run of hand-dipped beeswax candles.”  After all, when the power goes out he always reverts to the work of small and industrious insects, the honey bees, whose burning wax will shed light in his cabin.  Theobald can enjoy the process of making beeswax candles and can survive the exit of the bees from his life were his colonies to continue to wane because of CCD. Commercial bee keepers, as he says, cannot–as they are the most affected economically by the decline of the bees.   While one may be able to pinpoint the role of one specific pesticide in CCD,  the mystery of CCD is intensified as the interactions between the many chemical ingredients used in 21st century American agriculture become apparent.

Theobald takes my call on November 1, 2011, just before the storm.   This time we don’t focus merely on the systemic pesticide chlothianidin, but rather discuss the complexity of synergisms, the interactions of various pesticides on the health of the hive and the bee.  Theobald confides that fungicides “only entered his consciousness just recently,”  as part of a larger investigation into neonicotinoids, nicotine-derived pesticides.

As I mentioned in an earlier blog, fungi are crucial to the health of the hive.  They break down the pollen inside the hive.  As Theobald points out, fungicides disrupt the bee’s intestinal flora.  Bee bread is only a partly digested product that needs intestinal flora to be metabolized.  Fungicides, instead, “decrease the microbial diversity of the bee’s food source” according to David Doll, Farm Advisor for the University of California Cooperative Extension.  However, since fungicides, like pesticides, are required for a profitable crop, they become an integral element of the pollination process and therefore pose health risks to honey bees.

According to David Doll, fungicides are generally applied around or at bloom when they will adhere to the pollen. Their application during bloom should, therefore, be regulated.    Unlike Europe that errs on the side of caution, banning pesticides until they are proven not to be harmful, in the US there is, as reporter for the GMO journal Deniza Gertzberg points out, “no accurate and complete picture of what pesticides are used, where and in what amounts, or the accurate measures of just what the maximum exposure is in agricultural or urban settings on blooming plants.”

Jan Knodel, Extension Entomologist for North Dakota State University presents guidelines for reducing pesticide poisoning to bees:

As bees work the hardest during bloom, they will thus inevitably bring back the fungicide-laced pollen to the hive where they will store it to be eaten later or where it is eaten immediately, its nutritional value having been altered by the fungicides.

Theobald focuses on the fungicide boscalid in particular.  Introduced in the USA in 2003, boscalid, the active ingredient in the fungicide emerald, is a respiration inhibitor within the fungal cell.  It is highly successful in fighting fungal diseases in fruits, vegetables and grapes that are used for wine.

In the non-committal language of the EPA boscalid is “practically nontoxic to terrestrial animals and is moderately toxic to aquatic animals on an acute exposure basis.”  However, according to the PAN pesticides database,  “population-level effects on honeybees may occur even if a pesticide has low acute toxicity. […] certain pesticides interfere with honeybee reproduction, ability to navigate, or temperature regulation, any of which can have an effect on long-term survival of honey bee colonies.”

A recent study by James Frazier, professor of entomology at Penn State’s College of Agricultural Sciences highlights the magnitude of the problem of pesticides like boscalid making their way into the bee’s hives and lacing their food with poison: “on average six different pesticides, and in some cases, as many as 39 pesticides were found in hives across the United States.”   This  study focuses not on one specific pesticide but rather on the presence of multiple pesticides, in fact “98 pesticides and metabolites detected in […] bee pollen alone,” suggesting  the need for research on the synergisms between pesticides that might underlie the demise of the bees.

Theobald echoes the need for research on the potentially lethal synergisms of various pesticides on bees, as he refers to a 2010 report by the Cornell University Cooperative Extension stating the need for such studies, as “some fungicides may affect a bee’s ability to tolerate other pesticides.”

It is not only about chlothianidin.  It is not merely about boscalid.  According to Gertzberg, over 1,200 active ingredients are distributed among 18,000 products nationwide and are now integral to the honey bees’ landscape.  The complexity of the demise of the bees lies in the synergisms between these chemicals.