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To document which bee disease/parasites/pests of honey bees are present in Colorado and the U.S. and to provide information on the causes of honey bee decline. The survey will also evaluate pollen from sampled hives for the presence of exposure to pesticides.
Participating apiaries must have four or more hives. CDA will sample from 24 apiaries statewide. Past focus has been on apiaries with 8 or more hives. We want to get a more representative picture of honey bee health in the state.
The CDA will sample from 24 apiaries statewide. Past focus has been on apiaries with eight or more hives. This year we have approval to include apiaries with as little as 4 hives. We want to get a more representative picture of honey bee health in the state.
State Survey Coordinator
Apiary, Export, Nursery, PlantPest, Quarantine, and Seed Programs
Colorado takes part in the National Honey Bee Health Survey an initiative sponsored by United States Department of Agriculture, Animal Plant Health Inspection Service (USDA-APHIS) and the Bee Informed Partnership. Each year grant funding is available for CDA to sample 24 bee hives randomly scattered across the State.
Bee pollinators play a crucial role in natural and agricultural ecosystems, contributing over $200 billion in revenue from vegetable, fruit and nut production in the United States. The European honey bee, managed in hives, is actually considered ‘livestock’ by government policy and many laws.
Scientific surveys and research on honey bee health bear out that the past decade has been challenging for beekeeping with a decline in managed hives in the US. Ongoing media coverage continues to spread awareness among the public about the importance of pollinators in our food supply and ecosystems. This has led to a new generation of a hobby and part-time professional beekeepers, everyone intending to do their part to support bee health. The number of new beekeeping clubs and individual memberships in state beekeeping associations continues to grow nationally and in Colorado.
Honey bee researchers agree that there are many factors responsible for the challenges facing the valuable pollinator. Those are:
Results from the 2016 survey are in, allowing CDA valuable insight into the state of the state of managed honey bees in Colorado. A total of 67 apiaries (27% hobby and 73% commercial) have been sampled over 3 years of survey participation for the Varroa mite, several honey bee viruses that Varroa vectors and a fungal disease called Nosema. In addition, pollen and bee bread from 30 hives (10 per year) was also sampled for the presence/absence of over 170 pesticides.
To qualify, participating apiaries must have a minimum of 4, and preferably, more than 8 hives.
Samples of bees are collected and analyzed for the following parasites and diseases:
*replaced by Lake Sinai Virus (LSV2)
What have we found? SURVEY RESULTS from 2011 – 2013 – 2016
Results from the 2016 survey are in, allowing CDA valuable insight into the state of the state of managed honey bees in Colorado. A total of 67 apiaries (27% hobby and 73% commercial) have been sampled over 3 years of survey participation for the Varroa mite, several honey bee viruses that Varroa vectors and a fungal disease called Nosema. In addition, pollen and bee bread from 30 hives (10 per year) were also sampled for the presence/absence of over 170 pesticides.
Colorado has taken samples of qualifying apiaries (apiaries with a minimum of 4 – 8 hives; 8 hives preferred), in 21 counties in both urban and agricultural areas.
Chart 1. National Honeybee Health Survey results for Colorado; 2011, 2013, 2016. Percentage of apiaries testing positive for Varroa mite, Nosema and Varroa vectored viruses.
Because qualified apiaries were biased towards those involved in the commercial honey production and migrant pollination services, Colorado's hobby beekeeping community is underrepresented in survey participation. Nonetheless, results suggest that disease and parasite loads are significantly higher in hobby apiaries compared to those of their commercial counterparts. As shown in Table 1, Varroa mite was present in 78% of the hobby apiaries sampled, Nosema spp. present in over 40%, while Varroa vectored viruses were present in over 80% of hobby apiaries. Contrasted with commercial apiaries in which less than 40% have Varroa, Nosema and Varroa vectored viruses.
Varroa mites are parasitic animals that feed on the hemolymph (blood) of bees. Not only do Varroa mites cause injury to a honey bee by itself, they are also responsible for vectoring several honey bee virus diseases.
If left untreated Varroa mites can kill a colony in two or three years and are thought to be the single most significant reason for high colony loss numbers during the winter.
Nationally, surveys have determined that high Varroa mite numbers are particularly troubling for backyard bee keepers. Many backyard or hobby beekeepers do not have appropriate Varroa controls in place.
PESTICIDES FOUND IN POLLEN AND BEE BREAD – 2011- 2013 - 2016
Pesticide analysis data from the survey shows that the majority of pesticides found in pollen and bee bread sampled from hives in Colorado contain materials applied by beekeepers to control Varroa mite, a critical practice to insure that hives survive the winter. Results from Colorado’s data indicate that only 38% of hives managed by hobby beekeepers contain Varroa mite treatment residue. That suggests that 62% of hobby beekeepers may not be applying these important controls. In contrast our data indicates that 89% of the commercial beekeepers in Colorado do have appropriate Varroa controls in place (Chart 2).
Chart 2. Varroa applied pesticides by group
Honey bees pick up other pesticide residues in pollen as they forage, a small percentage of pollen sampled from hives (less than 20%) had herbicide residue present in it and an even smaller percentage of pollen sampled (7%) had insecticides used to control mosquitoes present in it. Researchers are still trying to understand the effects of herbicides and other pesticides, such as fungicides on pollinator health.
Table 1. The majority of pesticides found in pollen and bee bread during sampling were limited to the miticides and other materials beekeepers are using to combat Varroa mite and Nosema disease.
Pesticides* Found in Colorado Hives 2011, 2013, 2016
*Detection level in parts of billion
** Number of apiaries testing positive
National Survey Results
CDA is committed to continuing to participate in the National Honeybee Health Survey, to further our understanding and strengthen the data so that we can make meaningful decisions toward protecting the future of pollinators in the State.
"Most pathogens invade the digestive system through oral ingestion of inoculated food. These pathogens infect the mid gut epithelial cells, which are constantly being replaced and are protected by membranes and filters which confine the pathogen to gut tissue.
Parasites that infect the gut like Nosema apis and Nosema cerana can create lesions in the epithelium that allow a virus like BQCV to pass into the hemolymph and infect other cells in the body. In contrast, the external parasite Varroa destructor feeds directly on bee hemolymph providing an opening in the cuticle for viruses to enter.
Most virus infections rarely cause infection when ingested orally, but only a few particles are necessary to cause infection when injected directly into the hemolymph. Many viruses can be directly transmitted by Varroa mites, such as: DWV, those in the acute bee paralysis virus complex, and slow bee paralysis virus.
Other viruses, like sacbrood, have been detected in Varroa mites but Varroa has not been shown to directly transmit the virus. Some viruses, like DMV have been shown to directly multiply in Varroa mites, however, in most cases, we don’t know the exact relationship of Varroa mites to viruses or enough about how transmission occurs from mites to bees.
Knowledge about the presence, role and transmitting routes of these viruses in native bees, and other potential non-Varroa transmission routes is also lacking in detail, complicating recommendations for control.
Research does show viruses clearly affect honey bee health and warrant attention from the beekeeper and researcher alike.”
From: Honey Bee Viruses, the Deadly Varroa Mite Associates. August 19, 2015. Philip A Moore, Michael E. Wilson, and John A Skinner, Department of Entomology and Plant Pathology, the University of Tennessee, Knoxville TN.
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