What pesticides are hibernating with your honey bees?

by Michele Colopy

Now that it is November, honey bees across the U.S. have been moved to the south, the west, or “wrapped up and put to bed” for the Winter. Whether your honey bees were placed to pollinate crops, you moved your bees through a county or region to secure continuous nectar flows for a honey crop, or your bees sat in your backyard: they were all exposed to pesticides.
What pesticides are hibernating with your honey bees: lurking in the pollen, suspended in the honey, saturating the wax? No one is checking the pesticide residue load in the wax and honey prior to winterizing their hive. Many factors affect the lives of our honey bees, their survivability of Winter, including the sub-lethal or pre-lethal effects of pesticide residues that build up in their hives.

Studies have shown pesticides do not “stay put.” The EPA acknowledges this:
“Pesticides can move from the sites where they are applied into the surrounding environment through a number of different ways, including drift and volatilization. Pesticide drift can occur when pesticides move off the application site in the air as particles or aerosols during application or when the pesticides move that are attached to dust. Volatilization occurs when pesticide surface residues change from a solid or liquid to a gas or vapor after an application of a pesticide has occurred. Once airborne, volatile pesticides can move long distances off site. Fumigant pesticides (used to treat soil before planting and to treat structures such as homes or storage bins) are especially volatile.” 1

The National Coalition on Drift Minimization defines drift as, “The physical movement of pesticides through the air at the time of pesticide application, or soon thereafter from the target site to any non- or off- target site.” However, they continue to explain, “Pesticide drift shall not include movement of pesticides to non- or off-target sites caused by erosion, migration, volatility or windblown soil particles that occurs after application, unless specifically addressed on the pesticide product label with respect to drift control requirements.” 2

You can call it “drift” you cannot call it “drift,” either way honey bees and native pollinators are exposed to pesticides. Sub-lethal or pre-lethal, pesticides have an impact upon your bees. A study of trapped pollen in seven countries and beebread from 12 European countries found 72 of 107 trapped pollen samples contained one of 53 different pesticides. Seventeen of the 25 samples of beebread contained one of seventeen different pesticides.3

The International Bee Research Association published a study analyzing the hives of “amateur beekeepers from five U.S. states.” Besides finding chemicals normally used by beekeepers to protect against Varroa, the study found chemicals not used by beekeepers. Other “agricultural compounds were dimethoate, an organophosphate insecticide, a fungicide, and two herbicides.”4
IBRA Science Director Norman Carreck says: “In general, the levels of residues found in honey from the brood combs in this study were significantly higher than in the honey supers. Even though the amounts of pesticide found were well below the LD50 levels known to directly kill bees, because the brood nest honey is fed to developing bee larvae, there is a concern that these sub lethal doses of pesticide may harm bees. This study’s results support current concerns relating to the possible effects of sub-lethal doses of pesticides on bees and clearly demonstrates that further studies of this nature are needed”.4

A study reviewing four common pesticides toxicity to honey bee larvae found:
“All pesticides at hive-residue levels triggered a significant increase in larval mortality compared to untreated larvae by over two fold, with a strong increase after three days of exposure. Among these four pesticides, honey bee larvae were most sensitive to chlorothalonil compared to adults . . . We also tested the common ‘inert’ ingredient N-methyl-2-pyrrolidone at seven concentrations, and documented its high toxicity to larval bees. We have shown that chronic dietary exposure to a fungicide, pesticide mixtures, and a formulation solvent have the potential to impact honey bee populations, and warrants further investigation. We suggest that pesticide mixtures in pollen be evaluated by adding their toxicities together, until complete data on interactions can be accumulated.” 5

“A broad survey of pesticide residues was conducted on samples from migratory and other beekeepers across 23 states, one Canadian province and several agricultural cropping systems” that found “121 different pesticides and metabolites within 887 wax, pollen, bee and associated hive samples.”6

“Almost 60% of the 259 wax and 350 pollen samples contained at least one systemic pesticide, and over 47% had both in-hive acaricides fluvalinate and coumaphos, and chlorothalonil, a widely-used fungicide. In bee pollen were found chlorothalonil at levels up to 99 ppm and the insecticides aldicarb, carbaryl, chlorpyrifos and imidacloprid, fungicides boscalid, captan and myclobutanil, and herbicide pendimethalin at 1 ppm levels. Almost all comb and foundation wax samples (98%) were contaminated with up to 204 and 94 ppm, respectively, of fluvalinate and coumaphos, and lower amounts of amitraz degradates and chlorothalonil, with an average of six pesticide detections per sample and a high of 39.”6

Even a USDA study in Gastonia analyzing the pesticide residues in beeswax exclaimed “it was surprising to find more pesticides than expected.”7 The beehives in the urban area of Gastonia were found to contain coumaphos, fluvalinate, thymol, and chlorothalonil (a fungicide).
A 2011 study by Wu, Anelli, and Sheppard studied indirect and direct effects of pesticide exposure. They studied worker bees “reared in brood comb containing high levels of known pesticide residues (treatment) or in relatively uncontaminated brood comb (control). Delayed development was observed in bees reared in treatment combs containing high levels of pesticides particularly in the early stages (day four and eight) of worker bee development. Adult longevity was reduced by four days in bees exposed to pesticide residues in contaminated brood comb during development. Pesticide residue migration from comb containing high pesticide residues caused contamination of control comb after multiple brood cycles and provided insight on how quickly residues move through wax. Higher brood mortality and delayed adult emergence occurred after multiple brood cycles in contaminated control combs. In contrast, survivability increased in bees reared in treatment comb after multiple brood cycles when pesticide residues had been reduced in treatment combs due to residue migration into uncontaminated control combs, supporting comb replacement efforts. Chemical analysis after the experiment confirmed the migration of pesticide residues from treatment combs into previously uncontaminated control comb.”8
The sub-lethal effects of pesticide residues in the hive delayed larval development, delayed adult emergence, and shortened the life-span of adult honey bees. “In addition, longer development time for bees may provide a reproductive advantage for parasitic Varroa destructor mites.”8

The dose makes the poison: an immediate lethal dose, as well as the slow, long-term exposure to low doses of lethal toxins (or a cocktail of lethal toxins). The synergism with other pesticides, with pathogens, and pests impact the honey bee (and native pollinators) through direct contact with pesticides, low doses that build-up, residues that survive in the hive and in the food stores. In the end, dead is dead! Your bees may survive the Spring and Summer, only to die a slow death from toxic food, a toxic hive environment, and opportunistic pests and pathogens.
No matter your level of beekeeping, replacing combs, and decontaminating your hives annually may be the wave of the future. A researcher in Georgia annually scrapes the hive frames down to the foundation, removing the old wax filled with pesticide residues. For commercial beekeepers to manage such a feat they would have to have one set of colonies simply to create pesticide free comb that would be put into the comb of the migratory bees. When the migrant bees return, those frames would be scraped to the foundation, decontaminated and given to the bees that simply build comb. The remaining problem with that concept, is where can a beekeeper keep enough honey bees away from pesticide exposure and drift who will simply build pesticide residue free comb for the migrant bees? The philosophical question is why can’t the honey bees keep the food they collect? After eons, why is the food bees have always collected now weakening their immune systems, impairing their ability to navigate, creating a toxic home environment, and killing them?

Footnotes and Research:
1Pesticide issues in the works: pesticide volatilization, from EPAs website
2Power point presentation for Pesticide Drift From MSU Pesticide Education Program Michigan Groundwater Stewardship Program (MGSP),d.b2U
3The Bees Burden,Published April 2014 by Greenpeace Research Laboratories, School of Biosciences Innovation Centre Phase 2, Rennes Drive, University of Exeter, Exeter EX4 4RN, United Kingdom
4Overwintered brood comb honey: colony exposure to pesticide residues, Dr. Nancy Ostiguy and Dr. Brian Eitzer, Journal of Apicultural Research, vol. 53(3) pp. 413-421, July 4, 2014
5Four Common Pesticides, Their Mixtures and a Formulation Solvent in the Hive Environment Have High Oral Toxicity to Honey Bee Larvae , Wanyi Zhu mail, Daniel R. Schmehl, Christopher A. Mullin, James L. Frazier, Published: January 08, 2014, DOI: 10.1371/journal.pone.0077547
6High Levels of Miticides and Agrochemicals in North American Apiaries: Implications for Honey Bee Health, Christopher A. Mullin, Maryann Frazier, James L. Frazier, Sara Ashcraft, Roger Simonds, Dennis vanEngelsdorp, Jeffery S. Pettis, Published: March 19, 2010, DOI: 10.1371/journal.pone.0009754
7Pesticide Residue Detection in National Science Lab Beeswax, Posted by Michael Sussman, Science and Technology Programs, on August 2, 2011 at 2:45 PM
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8Sub-Lethal Effects of Pesticide Residues in Brood Comb on Worker Honey Bee (Apis mellifera) Development and Longevity, Judy Y. Wu, Carol M. Anelli, Walter S. Sheppard, Published: February 23, 2011, DOI: 10.1371/journal.pone.0014720