Metro Atlanta Beekeepers Association |
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Hazardous Working Zone Maryann Frazier, Chris Mullin, and Jim Frazier Department of Entomology, Pennsylvania State University Honey bee exposure to chemical pesticides has long been a concern of beekeepers and growers alike. A large portion of the country’s 2.4 million colonies is utilized for crop pollination, typically pollinating several different crops a season. These colonies are potentially at risk of exposure to the pesticides used by growers to control pest insects. Likewise, the need to use chemical pesticides within the hive to control Varroa mites has long been a concern in terms of the potential impact on developing bees, especially queens, and the possible contamination of hive products. In the past, our experience with pesticides has been associated with lethal exposure, indicated by the obvious symptom of a pile of dead bees on the ground in front of the hive. But we are increasingly concerned about how pesticides may affect bees at sublethal levels, not killing them outright but impairing their behavior or their ability to fight off pathogen infections. For example, pesticides at sublethal levels have been shown to impair the learning abilities of honey bees. For these reasons, pesticide exposure is one of the potential factors contributing to the honey bee decline currently under investigation. In 2007 we conducted a survey of pollen (bee bread), wax, and brood to determine if pesticide contamination is occurring and might be a potential factor in declining honey bee health and possibly Colony Collapse Disorder (CCD). In a total of 92 pollen samples analyzed, 43 different pesticides and five other metabolites were identified. Up to 17 different pesticides per sample were found. On average samples contained five different residues. Only three of 92 pollen samples lacked detections. The total pesticide load in the majority of the samples is of concern relative to bee health. Of particular concern, Aldicarb metabolites, ranging up to 1236 ppb, were found at two locations in Florida where trees were being treated for citrus greening disease, representing a combined level in pollen that exceeds current food tolerances for human safety. These multiple residues of different pesticides including insecticides from several chemical classes with fungicides and less commonly together with herbicides, result in a total pesticide load in pollen that raises concerns about the possible combined effects these may have on honey bee health from both acute as well as chronic exposure scenarios. CCD operations and analysis A large number of samples were analyzed as part of an in-depth, on-going study of the cause of CCD. Out of a total of 41 samples including 18 pollen (bee bread), 18 wax, and 5 brood samples analyzed to date (from CCD and control operations), 29 different pesticides were detected with as many as 13 detections per sample. Fluvalinate and coumaphos were found in 100% of the wax and brood samples. Fluvalinate was found in all but one of the pollen samples, although coumaphos was less frequent in pollen. Chlorpyrifos and fenpropathrin were also present in most of the bee bread samples. Chlorpyrifos and clorothalonil frequently occurred in wax. The most significant difference in pesticide levels relative to bee health was that fluvalinate residues tended to be higher in the pollen, wax, and brood of weak, dead, and recovering colonies relative to strong colonies. Highest levels of pesticides were found in the wax, followed by the pollen and brood, but levels in wax were much more variable than in pollen or brood. The fluvalinate levels found in brood are within a lethal range for honey bees. Conclusions The toxic chemical burden of honey bees is primarily a combination of both in-hive and out-of-hive pesticide exposures, the latter associated with residues in pollen and nectar brought into the hive. Unprecedented amounts of fluvalinate at high frequency have been detected in the wax, pollen, and brood of honey bees. Another in-hive miticide, coumaphos, and numerous environmental insecticides along with fungicides and herbicides have also been widely detected in these hive matrices. The large numbers and multiple kinds of pesticides could result in potentially toxic interactions. These chronic levels of pesticides in pollen, wax, and brood at potentially acute levels need to be further investigated in regards to their causative role in CCD. It is anticipated that increasing the breadth of multi-residue pesticide analysis of brood and adult bee samples, and its correlation with related pollen and wax pesticide residues, will provide valuable insight into recent declines in honey bee health. Have Your Wax Samples Tested Over the past few months I have been in search of pesticide-free wax, specifically wax free of miticides used to control Varroa mites. I acquired two samples of cappings wax from colonies which had no known history of pesticide use. Samples were sent to the National Science Laboratory in North Carolina to be analyzed for coumaphos (CheckMite®), and fluvalinate (Apistan®). Both samples came back with detectable amounts of coumaphos, fluvalinate, and the breakdown metabolite from coumaphos. This analysis was disturbing to both me and the beekeepers involved. If you would like to have your wax tested, you can send a sample to the USDA Agricultural Marketing Service. They will test samples for anyone who is interested. For amitraz (plus metabolites), coumaphos (plus metabolites), and fluvalinate the fee is $126.00 per sample. If you would like a comprehensive test which includes about 170 pesticides, the fee is $252.00 per sample. Below is the contact information. USDA Agricultural Marketing Service Roger Simonds, Supervisory Chemist National Science Laboratory 801 Summit Crossing Place, Suite B Gastonia, NC 28054 |