Honeybee Colonies in Decline - April 11, 2007
Jeff Schalau, Associate Agent, Agriculture & Natural Resources, Arizona Cooperative Extension, Yavapai County
I have been receiving some questions about the recent declines in honeybee populations. Since 1971, about one-half of the U.S. bee colonies have disappeared. These losses have been attributed to urbanization, tracheal and Varroa mites, beekeeper retirements, insecticide use, diseases, and other factors. However, in late 2006 honeybee declines reached new proportions and the phenomenon was given the name Colony Collapse Disorder or CCD. Similar losses were also recently observed in some European honeybee colonies and now scientists are working to sort it out.
Exact cause or causes of CCD are not known. However, one report came out of Penn State University saying that "During the last three months of 2006, we began to receive reports from commercial beekeepers of an alarming number of honey bee colonies dying in the eastern United States," says Maryann Frazier, apiculture extension associate in Penn State's College of Agricultural Sciences. "Since the beginning of the year, beekeepers from all over the country have been reporting unprecedented losses.”
Beekeeping is a $14 billion industry nationwide. Honey production is only one facet of the industry. Many agronomic crops rely on bees (along with birds, bats, and other insects) to pollinate them. Many beekeepers transport their bees from farm to farm following the bloom of various crops. A recent report by the National Research Council noted that in order to bear fruit, three-quarters of all flowering plants, including most food crops and some that provide fiber, drugs and fuel, rely on pollinators for fertilization.
During bee die-offs prior to CCD, the bodies of dead bees were often littered around a hive, sometimes carried out of the hive by worker bees. In cases of CCD no bee remains are found around affected colonies. Scientists assume these bees have flown away from the hive before dying. Some speculate that bees became weakened and lacked the strength to return to the hive while other think they may have become disoriented and were not able to find their way back. Bees remaining in the hives affected by CCD are often found to be infected with viruses, fungal infections, mites, and other pathogens. It is assumed that the bee’s immune systems are being depressed in some way.
One factor being investigated in CCD is a group of pesticides called neonicotinoids. Imidicloprid is a widely used systemic insecticide and a member of this pesticide group. Scientific research has indicated that imidicloprid can be absorbed by the plant and will find its way into the pollen and nectar. Some European scientists believe that bees gather and feed on this tainted pollen and nectar where they ingest a sub-lethal dose of imidicloprid. It is hypothesized that the imidicloprid could disorient and/or weaken the affected honeybee causing it to fly off and not return as well as becoming more prone to diseases. American scientists are being cautious about blaming pesticides as a possible cause of CCD and trying to see a bigger picture.
Some genetically modified crops (GMOs) , specifically Bt Corn have been suggested as a potential cause of CCD. Bt is a bacterium that has insecticidal properties. Scientists have isolated the gene with insecticidal properties and spliced it into various crop plants to protect them from insects. While this possibility has not been ruled out, CCD symptoms do not fit what would be expected in Bt affected organisms. For this reason GMO crops are not highly suspect at the moment.
Some beekeepers remember a similar phenomenon in the 1960’s that was called “disappearing disease”. However, those hives did not collapse as rapidly and the effect was not as widespread as the current outbreak of CCD. A CCD Working Group has been formed and causes are under investigation. Let’s hope they can figure this one out sooner rather than later.
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