BEEPOCOLYPSE?: COLONY COLLAPSE DISORDER

Many humans might not know just how important bees are to human existence as we know it today. The western (aka European) honeybee, or Apis mellifera, is perhaps the most familiar species to humans because of its annoying sting but also its deliciously sweet honey. The honeybee, however, is just one of around 20,000 known species of bees.


Did you know, though, that bees are also responsible for pollinating about 84% of the insect-pollinated crops that humans eat? To put this interdependency into a national context, in the US alone, one out of every three mouthfuls of food—including many fruits, vegetables, nuts, berries, and coffee—is a product of bee pollination. Without bees, Americans would lose many of the foods that provide them with a diverse, healthy, and nutritious diet.


With this in mind, I would like to look back at some not-too-distant bee history that reminds us of just how fragile and interdependent our ecosystem really is and what we can all do to help such tiny creatures as bees, which have such a huge impact on the world around us.

[Pollination of an apricot flower by a bee in early spring. Copyright: Karalevna 25, CC BY 4.0, via Wikimedia Commons]


WHAT IS COLONY COLLAPSE DISORDER?

In 2006, beekeepers around the world saw tens of thousands of honeybee colonies mysteriously dying off. These colony losses ranged between 30-90%, depending on the geographic location. Referred to as Colony Collapse Disorder (CCD), this phenomenon is characterized as a dead or dying colony with no adult honeybees but with a live queen, and usually honey and immature honeybees still present. Without the adult honeybees (worker bees), which care for and feed a colony, a hive is doomed.


The global emergence of CCD in 2006, and its continuation into subsequent years, made it apparent that, if left unmitigated, the loss in honeybee populations from CCD could create an existential crisis for honeybees. Moreover, if CCD were to continue at the same rate as when it emerged in 2006, this devastating global phenomenon could have impacted the food security of human communities that are dependent on bee pollination for their food staples.


In the first years of CCD, beekeepers and scientists saw massively declining native and managed bee populations around the world. With this came also the reduction of bee pollination of plants, including many plant-based foods that humans eat. Moreover, the loss of plant species resulting from reduced pollination impacted the food security for other animals as well, particularly for those animals that rely on bee-pollinated plant species for their own survival, and so on up the food chain.


CAUSES OF COLONY COLLAPSE DISORDER

Since CCD began occurring in 2006, scientists have established that there is not a single cause; rather, various factors contribute to this widespread phenomenon. For example, the use of chemical pesticides, especially systemic varieties (such as neonicotinoids) that are designed to kill ‘pest’ insects actually suppress also a bee’s immune system. This makes them more susceptible to health stressors. Even low-level exposure to chemical pesticides can compromise a bee’s health and immune system.

[Spraying of pesticides (by AMAZONE UG 3000 Nova) in spring. (Estonia). Maasaak, CC BY-SA 4.0. via Wikimedia Commons]


The introduction of new parasites, pests, and pathogens into the environment also weakens bees. Often acting as sub-lethal stressors, these introductions make bees more prone to pesticide poisoning. Reversely, when weakened by pesticides, bees also become more vulnerable to parasites, pests, and pathogen infestations that ultimately lead to CCD.


Increased urbanization and suburbanization have led to the loss of bee habitats. An abundance of prairies, meadows, and fields of wildflowers once offered bees a nutritious and diverse range of food resources for foraging. These natural green spaces have been rapidly disappearing. Consequently, the loss of dietary diversity and bee food stability leads to poor nutrition and compromised colony health.

[At Taberville Prairie Conservation Area in western Missouri. Copyright: Chris M Morris, CC BY 2.0, via Wikimedia Commons]


Bee habitat loss is further exacerbated in urban or suburban settings where herbicides and fungicides are used in green spaces to eliminate weeds and their flowers. Bees of all species rely upon these alternative food resources for their survival. So, when trees are not in bloom and nectar flows have stopped, bees head for the weeds and wildflowers in overgrown fields and roadsides!


Bee habitat loss is even more exacerbated by climate change. Increasingly warm winters in many regions of the world have impacted plant life cycles. In particular, the timing of seasonal blooms has begun to shift, often forcing premature flowering and nectar flows to occur before overwintering bees have re-emerged from their insulated clusters within the colony. Current studies show up to 50% loss of honeybee pollination of plants as a result of global climate change. These shifting plant cycles deprive bee populations of their much-needed food resources to keep their colonies healthy and strong, especially after harsh winters that contribute to the depletion of their internal stored food reserves. Deprived of sufficient nutrition, bees’ health and immune systems become compromised. They then become more susceptible to parasites, pests, and pathogens and, ultimately—as the vicious cycle continues—to CCD.


In managed honeybee colonies, apiary overcrowding, in which too many honeybee hives compete with each other for insufficient locally available food resources can also lead to a weaker colony. Likewise, when a queen bee in a managed honeybee colony has mated with a limited number of drones (male honeybees), the colony’s lack of genetic diversity can contribute to its inability to resist the kinds of sub-lethal stressors mentioned above. The hive is more likely to succumb to colony stressors and CCD.


Viewed alone, each contributing factor is not necessarily deadly to bees, but it does hamper their behavior, thus increasing their vulnerability to additional sub-lethal stressors. On the other hand, a combination of these often overlapping and interactive factors can directly harm, even kill, healthy bee colonies. This was the case especially between 2006 and 2013, for example, with the loss of over 10 million honeybee colonies around the world.


MITIGATING COLONY COLLAPSE DISORDER

Since the first major outbreaks of CCD in 2006, scientists and beekeepers have worked together to become increasingly aware of what to look for in CCD causation, to understand the impact of sub-lethal stressors on hi