What is in this article?:
- Pesticides get undue blame in honey bee decline
- Genetic bottleneck
- Multiple factors contribute to the declining honey bee population, not just one class of insecticides.
- Multiple factors affecting colony health include pathogens, parasites, pesticides and malnutrition.
- Beekeepers continue to lose 40 to 100 percent of their colonies annually.
Mussen, in a recent talk at a UC Cooperative Extension seminar in Woodland, advocated that the bee toxicity tests conducted by the Environmental Protection Agency (EPA) and the California Department of Pesticide Regulation (DPR) “be of a longer time frame.” Current regulations “specify that they be completed in 96 hours, which is too short of a time period to see what happens to the bees.”
“Sublethal effects are not required, chronic exposure to sublethal effects is not required and synergism is not studied,” he said.
“Synergies easily could be the biggest problem,” Mussen said. “Coumaphos (an acaricide used for mite control) knocks the daylight out of queens when it’s in the pollen. “Fluvalinate (synthetic pyrethoid commonly used to control varroa mites) synergizes Coumaphos, and vice versa.”
Mussen cautioned that adjuvants can be toxic. “Adjuvants seem to make non-toxic fungicides toxic to honey bee brood, especially the organosilicone ‘superspreaders,’” he said. “The superspreader can penetrate the waxy cuticle of leaves, such as Eucalyptus leaves. And the waxy cuticle is the No. 1 bee protection.”
Also at the Cooperative Extension seminar, Mussen called for greater genetic diversity in the honey bee and a loosening of the “genetic bottleneck” in the United States. “Unlike dogs and horses, there are no pedigree bees and no papers, he said. “There are few true breeding lines, but they include the New World Carniolans (developed by bee breeder-geneticist Susan Cobey of UC Davis), Russians, Minnesota Hygienic, and the Varroa Sensitive Hygiene.”
“Most breeders simply select from last season’s best performing stock,” he said. They breed for certain company traits, such as color, gentleness and brood pattern.”
Mussen pointed out that in 1922 the United States closed the door to live bees entering our country” due to fears of an incoming pest, the tracheal mite.
The tracheal mite eventually found its way to the United States in 1984, he said. “We couldn’t prevent it from coming in forever. It killed half of our nation’s bees in five years as it expanded across the country. Then the varroa mite arrived in 1987, and killed half of the remaining colonies in five years as it expanded across the country. This one practically killed all of our feral colonies in 1995-1996. It made a really big dent in our gene pool.”
Mussen described the varroa mite as “Beekeeping Enemy No. 1.” Mite feeding lowers the pupal blood protein, resulting in underweight bees and a shortened life span, he said. It suppresses the honey bee immune system. And third, the mite is a vector for RNA virus diseases.
Of the viral diseases affecting the honey bee, RNA viruses are the most prevalent. “We have 20 known and named viruses, and more are coming,” Mussen said. Some of the viral diseases are shared with bumble bees, wasps, ants, other native bees and other unrelated species of insects.
Asked what the average person can do to help the bees, Mussen said that a wide mix of pollen is essential for honey bee nutrition, and “they’re not getting that any more. Plant bee attractive plants. Each colony needs the equivalent of one acre of bloom every day to survive.”
What about the role of genetically modified plants in bee health, he was asked. “They don’t appear to be a problem. One modified corn variety seemed to affect honey bees in lab studies, but it’s not being grown anymore. The honey bees don’t care if it’s genetically modified or not.”
As for viruses, “The harder we look, the more we find,” Mussen said.