What is the Biggest Challenge to Honeybee Hive Health?

CLAIM: Colony Collapse Disorder is the biggest threat to honeybees.
REALITY: CCD is a relatively small threat to honeybees compared to other well-known challenges.

“With a third of honeybee colonies disappearing due to ‘colony collapse disorder,’ it’s time to move into high gear to find a solution,” claims one Mother Jones article on the topic. But to find a solution, we need to understand the problem, and CCD is really not the main challenge facing honeybees.honeybeeonwatermellonflower

Not all honeybee losses are related to CCD. Honeybees die and disappear for many different reasons. The phrase “colony collapse disorder” refers to losses that occur along a very specific set of circumstances. Researchers attribute hive losses to CCD when most or all adult honeybees disappear from the hive, leaving behind honey, a live queen, and immature bees. According to a 2010 United Nations Environment Programme study, about 7 percent of hive losses are attributed to CCD, and the remaining 93 percent to other causes.

In fact, the real issue is not so much CCD, but instead hive health, which is affected by a number of factors. While each factor alone might not present much of an issue, it is the combination of such stressors that lead to poor hive health and periodic annual declines. Such stressors include diseases and parasites, poor queen bee health and limited generic diversity, hive transport for pollination services, nutritional issues, and a number of different pesticides.

Diseases and Parasites. Of all the factors impacting bee hive health, natural pests and diseases is quite significant. A 2009 study on hive health by Dennis vanEngelsdorp of the University of Maryland and other researchers underscores the significant role that pathogens play in hive health. In January and February 2007, the authors examined 13 apiaries owned by 11 beekeepers with a total of 91 bee colonies. They divided up the apiaries into one of two groups: a control group for those lacking CCD and another for apiaries that experienced CCD. They found that colonies affected by CCD had more pathogens—bacteria, viruses, and parasites—in the hive, and therefore a higher “pathogen load” than did the healthy hives, although no single pathogen or other variable was found to be more prevalent than others.

Some of these pathogens and parasites originate domestically but as beekeeping has become a global industry, different diseases have spread around the world through increased trade. These diseases may contribute to, or cause, some CCD cases. One researcher at the Department of Agriculture’s (USDA) Agricultural Research Service (ARS) says the first two of these diseases listed below are recognized as “probable” contributing factors. In any case, the diseases affecting honeybees are many. A few examples include:

  •  Varroa destructor mites. Accidentally imported into the United States in the late 1980s, the Varroa destructor mite is “the most detrimental honey bee parasite in the world today,” according to honeybee researchers. It has already nearly eliminated wild honeybee populations in the United States. These mites feed on honeybees and larvae. That is bad enough, but they also transmit secondary diseases, such as a virus called “deformed wing disease,” that can decimate hives if left uncontrolled. These mites have not destroyed commercial beekeeping, but they have increased annual hive losses and raised beekeeping costs. That appears to have reduced the number of small beekeeping operations and increased larger scale commercial beekeeping.
  • Nosema. Nosema is a disease transmitted by microsporidian parasites that enter honeybees as spores and then develop in the honeybee gut, where they weaken the bee and lead to premature death of adult bees and queens. Bees pass the spores via excrement, which builds up in the hive, particularly during the winter. Symptoms are hard to detect and beehives may recover, but only after many bees are lost.
  • Tracheal mites. First discovered in 1984 in Texas, these microscopic sized vermin inhabit the trachea of young adult honeybees, where they feed on the bees’ blood, affecting the bees’ development, ability to fly, and overall health. The mites easily spread from one bee to the next, with many infections occurring during winter hibernation and into the spring. Tracheal mites are controlled with Menthol crystals, which is a registered pesticide with the U.S. Environmental Protection Agency.
  • American and European foulbrood. American foulbrood is a bacterial disease that kills bee larvae in the honeycomb. The larvae first eat the bacteria’s spores that have contaminated their food. The spores then develop in the larvae gut, consuming its food, releasing more spores into the hive, and spreading the disease. The disease is hard to control because spores can remain viable up to 40 years and because each attached bee larvae can release up to a million spores. Burning the hive and related equipment, and then starting a new hive with sanitary controls may be the only option in some cases. Antibiotics may help treat infection, but cannot eliminate the spores, and the bacteria are growing resistant. Fortunately, researchers are making headway in finding a cure. European Foulbrood is similar, but not as dangerous, and some hives recover from it.

Queen Bee Health. In a healthy hive, queen bees usually lay eggs for about two years, populating the hive with worker bees as well as with the male drones that mate with the queen. But sometimes queen bees fail to produce enough offspring or mysteriously die, undermining hive health. In some cases worker bees will even kill off their own queens early if there is a health problem. Limited genetic diversity among the commercially farmed bees may contribute to poor quality queens, but the causes are not fully understood.  A  United Nations Environment Program report highlights the fact that poor quality queens is an even more significant problem. The report notes: “CCD only accounts for about 7% of losses in the USA, and even less in Europe. The loss of queen bees seems to be a much more common cause at about 25%.” In the United States, beekeepers reported premature death of queen bees in 32 percent of their hives.

Hive Transport and Pollination Services. Honeybee hives in the United States are farmed at various locations around the nation and then trucked to farms in the spring and summer to pollinate crops, with many hives visiting more than one farm every growing season. Such movements, although necessary, represent yet another stress that affects hive health. A report in Agricultural Research Magazine notes: “At the same time [as honey production moved overseas], the call for hives to supply pollination services has continued to climb. This means honey bee colonies are trucked farther and more often than ever before, which also stresses the bees.” In addition, the movement of hives aggregates bees and diseases they carry, increasing transmission, as the bees move from one region to the next.

Nutritional issues. Farmed honeybees spend much of their time pollinating a limited number of crops, which means their nutritional sources may be too one dimensional. And many times beekeepers supplement the hive diet with are fed high-fructose corn syrup, which offers limited nutritional value. Bees achieve better health when they can forage among a wider range of pollen and nectar sources. “Although honey bees may store food (in the form of honey and packed pollen) for times of dearth, lack of diverse floral resources is now demonstrated to diminish their immune response,” explain researchers in Environmental Science and Technology.

Pesticides. Ironically, the pesticides that pose the greatest exposure and risk to honeybees are also necessary to control some of the diseases that would otherwise destroy hives: fungicides and mitocides used directly inside the hives. These products pose risks to hive health, but they are necessary for survival. Of all the causes discussed here, agricultural pesticides appear to play one of the smaller roles, yet headlines focus on them. This is in part because they are the subject of regulation in Europe that warrants news coverage. But much of the news coverage derives from misinformed alarmism about these chemicals.


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