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.
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 hive health and colony losses, and to find ways to reduce such stressors. Consequently, most beekeepers have changed how they manage their hives to avoid weakening honeybee colonies which can ultimately lead to colony loss. Although beekeepers today are not seeing the massive colony losses experienced in the early years of CCD, maintaining the everyday health and well-being of honeybee colonies continues to challenge beekeepers worldwide, often with wide-ranging regional differences in the numbers of hive losses.
For example, a nationwide survey conducted in the U.S. between April 2014 and April 2015 found the smallest loss of honeybee colonies occurred in Hawaii at 13.95% while the largest rate occurred in Oklahoma at 63%. Although the comparatively low occurrence of CCD among managed honeybee colonies in Hawaii was cause for celebration among beekeepers, seven types of native Hawaiian, yellow-faced bees were added to the endangered species list in 2016! These were the first bees ever to be added to this list! Such dramatic threats to native bee species also were found elsewhere in the world. In Hawaii, the loss of diversity in native plant species and the increase in invasive plant species crowding out and/or killing off native plants has greatly contributed to the decline in native Hawaiian, yellow-faced bees as their diet is exclusively based on native plant species.
With growing awareness about CCD and the need to protect the world's bees, there has also been a growing interest in beekeeping, in efforts to help mitigate the decline in honeybee populations. The increase in beekeeping certainly has had a positive impact but more needs to be done. In 2018, the U.S. alone saw an average of 41% loss of honeybee colonies due to CCD, In 2020, the U.S. Department of Agriculture reported that American beekeepers lost 105,240 colonies just in the early months of the year. These statistics presented a 76% increase from 2019 and the highest total since 2016.
Since the emergence of CCD in 2006, scientists and beekeepers have made great strides toward reducing the massive losses of bee colonies seen in the initial years. For example, through collaboration, they have developed new solutions to strengthening colonies and reducing potential stressors to managed honeybees. For example, queen bee breeding programs seek to identify and produce honeybees that are more equipped to cope with environmental stressors. Hawaii is home to the world’s leading breeders of honeybee queens. Many of them have successfully identified and selected specific traits that help strengthen a colony’s chances of survival. Breeding queens are selected with particularly strong traits of improved hygienic behavior, which they pass on to worker bees that are especially inclined toward hive cleaning, specifically, removing dead/dying brood from the hive. This important trait results in the worker bees more quickly ridding the colony of potentially harmful pathogens. Queen bees are also identified and bred for greater resistance to certain types of pests, such as the dreaded varroa mite, a tick-like parasite, which is one of the greatest threats to managed beekeeping today.
[A varroa mite, Varroa destructor, on a honeybee pupa. Copyright: CSIRO, CC BY 3.0, via Wikimedia Commons]
Scientists continue to develop medications and mitigating treatments for weakened colonies or sick bees as well as to create innovative beekeepers’ tools that are capable of better monitoring the health of their bees. Small devices, for example, are being developed that will be able to ‘listen’ and ‘smell’ inside hives to give beekeepers a more direct indication of a colony’s health.
The successful efforts of scientists and beekeepers in reducing CCD, especially among managed honeybee colonies worldwide, can be greatly improved through public awareness about the multiple causes of the phenomenon and the means to mitigate sub-lethal stressors not just for honeybees but for all bee species. Crucial steps can be taken at both the individual and communal level include eliminating or reducing the use of chemical pesticides, herbicides, and fungicides in gardens; planting bee-friendly gardens and fields; mowing lawns less frequently; allowing patches of weeds to grow and blossom; planting native wildflowers and plant species in public green spaces; installing freshwater features for thirsty bees; placing native bee houses in the yards and parks; adopting and/or supporting organic practices; engaging in community projects for the preservation of all bees; helping to mobilize local communities to plant and maintain bee-friendly gardens in urban, suburban, and rural settings; supporting legislation that bans the use of harmful pesticides, fungicides, and herbicides; reducing one's carbon footprint; participating in political activism to stop climate change; and, last but not least, supporting your local beekeeper!!
Bees are such an important element in the interdependence and survival of so many plant and animal species (including ourselves). So, as we all continue to do our part in caring for our Earth, let us remember also our busy little friends and the lessons that Colony Collapse Disorder has taught us about the importance of these tiny creatures to life on Earth as we know it.