A honey bee queen surrounded by helping workers. Photo Credit: Pixaby Photo

In the winter of 2006-2007, beekeepers across the U.S. reported losses of 30-90 percent of their hives. The phenomenon was named colony collapse disorder (CCD). It’s defined by honey bee colonies missing adult workers, where only a struggling queen and a few juvenile workers remain. Recently, researchers found new ways to protect vulnerable colonies. The average annual loss rate of honey bee colonies has dropped to 39%. The rate is still bad, and CCD still threatens honey bees. This article will explain why honey bee colonies are so vulnerable to CCD.

The inner workings of a honey bee colony

     The western honey bee (scientific name Apis mellifera) is a famous and fascinating animal. They are known for their ability to produce honey and other valuable products such as beeswax, propolis, and royal jelly. Honey bees are eusocial, meaning they depend on a large familial lifestyle. 

     Some honey bees are wild, found in the cavities of trees, or anywhere else they can build their homes. However, in the U.S., where honey bees are non-native, most are kept by beekeepers. Beekeepers’ hives provide a sheltered cavity where bees can build comb, store food, and live while making inspection and honey collection easy for their caretakers. 

     A colony consists of one queen, tens of thousands of female worker bees, and a couple of hundred male drones. The queen bee is the only egg-layer of her colony and can live up to five years. Workers, making up the majority of their colony, perform dozens of important tasks to maintain living conditions. Some of these tasks include foraging for nectar and pollen, caring for young, and defending the nest. 

     Without the presence of workers, honey bees wouldn’t be able to survive and pass down their genes. The queen bee, unable to perform any other tasks, besides egg-laying, depends on her daughters. Because of this, colony collapse disorder is fatal to the remaining queen bee and her babies, because no one remains to care for, feed, or protect them.

Culprit #1:  Toxic Pesticides

     A new class of pesticides, called neonicotinoids, was developed in the mid-1990s. It’s now widely used in agriculture because it’s effective, easy to apply, and non-toxic to most wildlife.  Unfortunately, neonicotinoids decimate pollinator populations, including bees. These pesticides, unlike many others, accumulate in the pollen and nectar of plants that honey bees depend upon. Neonicotinoids lead to lower cognitive ability in adult bees, and lower survival among brood. The popularity and accumulation of these pesticides in soil and organic matter coincided with the 2006 observance of CCD.

Culprit #2:  Pathogens

     Honey bee hives provide a tempting environment and food resource for pests and pathogens. Beehives are warm, perfect for incubating bacteria and viruses. Their honey, as well as the larvae growing in the comb, are a nutrient-rich food source that must be constantly protected. Over time, more and more pathogens and pests have been identified that pose risks to honey bees. Currently, and during the rise of CCD, one of the most prominent and dangerous pests is a small mite known as Varroa. 

     Varroa parasites attach to the bodies of both adult and larval honey bees and suck their bodily fluids. Varroa can impair the function and survival of parasitized individuals, as well as spread diseases such as Deformed Wing Virus. The mites reproduce in brood comb, where immature bees grow. These invasive creatures have become so deadly for honey bees that even the most “natural” beekeepers are forced to intervene. Colonies must be regularly measured for infection rates, and chemical treatments must be applied to kill the mites. 

This honey bee has been parasitized by Varroa. Photo credit: Alex Wild

Culprit #3:  Loss of Forage

     As the human population expands, natural spaces have been converted to residential or agricultural land over time. Other factors, such as increased biofuel production, have contributed to the loss of flowering plants across the country. If honey bees cannot find enough nectar from the plants growing around them, they cannot produce enough honey to sustain the colony over the winter. Loss of foraging resources is classified as a cause of CCD.

Culprit #4:  Modern Management Stress

     In addition to your friendly backyard beekeeper’s hives, commercial apiaries have been a growing industry in the U.S. Commercial apiaries are bee yards containing hundreds of hives or more. This industry supplies the ever-increasing demand for honey and provides pollination services to farmers. Did you know that California’s almond industry depends on the rental of honey bees that supplement the lack of available, local, almond pollinators? Unfortunately, commercial beekeeping is hard on honey bees. Commercial beekeepers tend to harvest as much honey as possible from hives and feed their bees in the winter with artificial replacements, such as high-fructose corn syrup. This takes away the medicinal benefits the bees receive from their own honey, resulting in poor nutrition. The size of the apiaries and close contact in travel lead to a higher risk of pathogen spread and losing workers in travel. 

No Singular Convict:

     While the above factors are clearly linked to the phenomenon of CCD, it is impossible to trace it back to one cause. CCD is still the spearhead of modern honey bee research, as we scramble to protect these essential insects. There may be dozens of other reasons for CCD, and more may emerge in the future. What matters is taking action and accountability for the known culprits, and changing our behavior to prevent further damage.