   Honeybee Colony Collapse Update - January 21, 2009 Jeff Schalau, Associate Agent, Agriculture & Natural Resources University of Arizona Cooperative Extension, Yavapai County In late 2006, honeybee declines reached new proportions and the phenomenon was given the name Colony Collapse Disorder or CCD. Honeybee losses have also been observed in some European honeybee colonies and scientists have been working diligently to discover the cause(s). Bees with CCD seemingly “disappear” from the affected hive. To date, honeybee researchers have attributed their disappearance to a variety of factors including urbanization, tracheal and Varroa mites, insecticide use, diseases, viruses, and other factors. Exact cause or causes of CCD are still not known. However, new tests suggest how a virus nicknamed IAPV could partially explain the bee’s disappearance. IAPV is an acronym for Israeli acute paralytic virus. Diana Cox-Foster of Pennsylvania State University reported at the annual meeting of the Entomological Society of America (Reno, NV, November 2008) that during tests on hives placed in a greenhouse, bees infected with IAPV rarely died in the hive. Sick bees expired throughout the greenhouse, including near the greenhouse wall. Viruses belonging to the group including IAPV linger in pollen. Cox-Foster said that she and her colleagues have for the first time isolated bee viruses from pollen samples from outdoor hives, though IAPV itself was not found. In another study, the same viral strains showed up in wild bees and neighboring domestic hives. “Our conclusion is the strains are circulating freely,” Cox-Foster said. Even though the viruses don’t affect mammals and bee products would not be a threat to people, infected bees might contaminate visited flowers, perhaps spreading the virus to uninfected colonies. 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. Roughly a third of food production worldwide depends on pollinators such as bees. North American farmers start renting honeybees in February to ensure pollination of the almond crop, and continue renting bees for other crops throughout the growing season. Rental prices for bees are rising, in part because of CCD. Price changes affect the economics of crops nationwide and, ultimately, the prices paid by consumers. Researchers are fairly certain that IAPV is not the sole cause of CCD. This is because seemingly healthy bees have been found to be carrying the virus. Scientists conjecture that these bee colonies were healthy enough to cope with IAPV and not display symptoms of CCD. In addition, greenhouse-based experiments are known to stress honeybees without other factors such as CCD. While greenhouse studies are not the best way to conduct CCD research, it is currently the only way to isolate the bees from the outdoor environment. Several studies have failed to find links between colony collapse and acute exposure to crops genetically modified to produce the Bt (Bacillus thuringiensis) pesticide. Several agronomic crops (corn, cotton, and potatoes) have been genetically modified to produce the Bt toxin which is harmful to larvae of butterflies and moths that eat the Bt plant. Some readers may remember the Bt scare of corn pollen and monarch butterflies that was in the media in 1999. Fortunately, the “scare” proved unfounded for monarch butterflies. Subsequent studies have also shown that Bt crops are not harmful to honeybees. Conventional pesticides are still under suspicion for being linked to CCD. Residues of 75 pesticides have turned up in honeybee pollen samples, according to scientists working on CCD. The pesticide list includes chemicals that are no longer in wide use, such as DDT. This work will certainly continue. However, the root cause of CCD remains mysterious and will likely take several years to sort out. Much of the above information was pulled from and article in Science News, December 20th, 2008; Vol.174 #13. The University of Arizona Cooperative Extension has publications and information on gardening and pest control. If you have other gardening questions, call the Master Gardener line in the Cottonwood office at 646-9113 ext. 14 or E-mail us at cottonwoodmg@yahoo.com and be sure to include your address and phone number. Find past Backyard Gardener columns or submit column ideas at the Backyard Gardener web site: http://cals.arizona.edu/yavapai/anr/hort/byg/. |