Also Check Out: USDA Website on CCD for Updates, including this May 2008 Article. The Plan for Action on CCD drafted in 2007, is also available for download.
“The Potential Impact of Pesticides on Honey Bee Health” 
Presented by: Maryann Frazier
Apiculture Extension Associate
Pennsylvania State University
Summarized by an MCBA Member
“The Potential Impact of Pesticides on Honey Bee Health” was the title of the talk given by Maryann Frazier at the June 24, 2008 Southeastern PA regional beekeepers’ meeting held at Keeney & Ziegler Apiaries, Bethel, PA. Maryann Frazier is an expert on honeybees and an apiculture extension associate working at Penn State University. More than 100 beekeepers from our region attended the meeting, which began in the bee yard with nucs, proceeded to the lecture, and ended with birch beer and sweet treats, courtesy of Keeney & Ziegler. Photos by: Bill Mondjack © June 2007
Throughout the lecture, Maryann gave frequent credit to her colleagues at Penn State, USDA and EPA in their cooperative efforts to research Colony Collapse Disorder (CCD) and to evaluate the impact of agrochemicals on the honeybee. The national press that CCD is receiving has resulted in significant media attention to the plight of the bees and has served to focus the public on the importance of the honeybee in agriculture and our ecosystem. This has led to significant donations of funds for research as well as renewed interest in becoming involved in beekeeping. While the syndrome is devastating, the positive outcomes of more honeybee research, greater attention to the chemicals that we use in our environment, and the surging interest in beekeeping will benefit all of us in the long run.
Pennsylvania beekeepers have served a central role in the investigation of CCD. One of the first to identify the problem of CCD was Dave Hackenberg, a PA beekeeper. Although in Florida at the time, he immediately notified agricultural associations and scientists of his concern over his empty and failing hives.
Although declining populations were in the news as early as 2004, the National Academy of Sciences published their study, the
“Status of Pollinators in North America” in 2007 that helped to raise the alarm for CCD. The report highlighted through studies conducted in 2005/6 that pollinators of many types are in decline. In the journal
Science, in 2006, European studies similarly confirmed that European pollinators were also found to be in decline. The decline was especially severe in those that specialized on particular plant species. The reciprocal relationship between the two affecting both species.
Of current interest to researchers investigating CCD are links between agrochemicals and the honeybees. Are the bees being poisoned by the chemicals we use on agricultural crops? Neonicotinoids in particular are getting a lot of attention by toxicologist and entomologists studying CCD and its potential causative factors, although many pesticides and herbicides are being evaluated.
(See article regarding a recent ban on the neonicotinoid family of compounds in Germany.)
To evaluate potential links, scientists have studied:
Scientists first identified 171 typical pesticides, herbicides and other agro-chemicals that honeybees are likely to be in touch with. Using Liquid and Gas Chromatography analyses coupled with Mass Spectrometry (LC/MS-MS and
GC-MS) it is possible to test samples collected from collapsed, near-collapse Photo: B.Mondjack©Oct2006
and healthy colonies down to part per billion (ppb) levels. back to top
What Has Been Found?
One hundred eight (108) pollen samples showed forty-six (46) different pesticides and their metabolites. Among the culprits found were:
8 pyrethroids (including fluvalinate and bifenthrin)
5 organophosphates (including coumophos and chlorpyrifos)
4 carbamates
3 neonicotinoids (group to which banned German chemistry and French restrictions apply)
3 insect growth regulators
2 organochlorines
1 chlorinated cylcodiene
6 herbicides
As well as several systemic pesticides
Formic acid and oxalic acid were not found. But the volatility of these compounds is such that their absence is not surprising. This makes scientists believe that these two compounds are ideal for treatment as they do not have residuals that will harm the bees long term.
In pollen samples tested, the average sample showed five (5) pesticides. One sample had as many as fourteen (14) pesticides present. Of the 108 samples tested, only three (3) samples showed none. In other words, > 97% of the samples tested contained pesticides.
Fluvalinate and coumophos were the most commonly found pesticides. These compounds are frequently used by beekeepers in the control of varroa mites and other hive pests such as the hive beetle. Although these compounds also have minor uses in other forms of agriculture, by far the biggest consumption of these two chemistries is through hive maintenance. Chlorpyrifos, an insecticide, was also found frequently in pollen samples.
Pollen results were from bee-bread as well as trapped pollen. Since the trapped pollen was also found to be contaminated, the prevailing theory is that the adult bees are carrying the pesticides to the flowers on their mouth parts and on the external parts of the bee.
Ninety-two (92) brood nest wax samples were also contaminated in a high percentage of the samples tested. 100% of samples contained fluvalinate and coumophos. Bifenthrin was only found in three (3) of the ninety-two (92) samples, but it is a very toxic compound for bees, with an LD
50 of 0.015 μg / bee. Compared to fluvalinate, for which the LD
50 is 0.2 μg / bee.
(Don't know what LD50 means? Click here.)In this study, the age of the wax was not known, as the current hive management practices typically do not date the foundation as it is placed in the hive. However, “new” foundation was tested, and fluvalinate and coumophos were both detected. This indicates that the processes used to treat and process beeswax to make wax foundation do not eliminate the risk of carryover of pesticides.
Scientists are currently working with foundation manufacturers to help reduce the prevalence of contamination in “new” foundation by modifying their manufacturing and treatment techniques.
Only five (5) brood samples were tested, however 100% of the samples had fluvalinate and coumophos. 172 – 937 parts per billion (ppb) was the range found. Since the LD
50 is one part per million (1 ppm, which is equivalent to 1000 ppb), this maximum level found in samples is nearly a toxic dose.
Up to twenty-four (24) types of pesticides were identified in adult bee samples.
The presence of these contaminants at all levels of the hive (wax, pollen, brood, adults) is a considerable problem for bees which are exposed to these chemicals throughout their life-cycle and in every day activities.
Honey was not sampled as part of this series of tests, however USDA / EPA are currently testing honey and the results should be out shortly. Thus far, no levels have been found that would be harmful to humans.
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Why are the Colonies Collapsing? And Other Unanswered Questions
Key questions with all of the contamination samples are whether the exposures that were seen in samples are due to maverick, off-label use, or whether the increase in prevalence of these chemicals in hives was still occurring with proper use.
There was anecdotal information from individuals with very well-documented miticide use, that showed that even after one or two uses of fluvalinate when the product was first released in 1998 and no repeat use in the hives, that their hives still shows a high rate of contamination. This indicates that the pesticides are persisting in the beehives over long periods of time.
Although the pesticides found are quite toxic, they were still present at levels that we understand to be close to, but below, the level that would be Photo: Bill Mondjack © Jul 2007 considered toxic for bees. So why are the colonies collapsing?
There are unanswered questions about the effects of these sub-lethal doses of pesticides and herbicides on bee behavior such as navigation, communication about food sources, as well as effects on the pheromones and chemical cues on which the bees operate.
There are unanswered questions about the effect of these pesticides and herbicides on bee health that might affect their ability to fight off infections (e.g., nosema ceranae, or Israeli acute paralytic virus)
There are unanswered questions about the persistence of chemicals in the environment outside of the hive (e.g., soil, trees, flowers) and how the chemicals might impact the flower pollen and nectar on which the bees feed. This work has been begun at Penn State and will be continuing.
Anecdotal evidence from CCD hives are that hive beetles, robbing bees, wax moths are not present for several weeks after a collapse. We don’t know the answer as to whether the hives are toxic, or whether these scavengers are failing to get some cue from the hive when it collapses.
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Banning Chemical Usage is Not the Solution
What does LD50 mean? What about TLV?
LD
50 stands for Lethal Dose 50. It is the amount of a material that, when administered to a population of animals or insects at the stated level, will be lethal for 50% of the population tested. For example and LD
50 of 0.015 μg / bee means that 15 trillionths of a kilogram will kill 50% of the bees that are exposed. The LD
50 is established during safety testing conducted during product development.
(return to What Has Been Found)TLV, or Threshold Limit Value, on the other hand, is an occupational exposure level frequently printed on the MSDS (Material Safety Data Sheet) or label of a product. It is the maximum level to which a person can be safely exposed to that product when in use in accordance with the personnel protective equipment described on the label. The level is the amount believed a worker can be exposed day after day for a working lifetime without adverse health effects. The TLV does
not relate to the amount that can be safely ingested as TLV values are typical inhalation or skin exposure related.
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