For nearly a decade, the declining health of bee colonies has been a growing concern for entomologists and conservationists around the world. Beginning in 2006, beekeepers started to report unusually heavy losses in their honey bee populations. Since then, the rate of bee deaths has shown little sign of improvement, with average winter losses in the U.S. at 28.7 percent.
The magnitude of the current trend is still difficult to determine. Since winter losses are normal and because colony deaths vary widely from year to year, it is difficult to say how rapidly bees are dying or even whether imminent extinction is inevitable at the current rate. In the U.S., however, the rate of winter and yearly losses has remained significantly higher than normal for the past eight years, and some sources estimate that as many as one-third of honey bee colonies in the U.S. have already been wiped out. Therefore, it would be difficult to argue that there is not some cause for alarm.
Bees are important primarily because of their role as pollinators. They are responsible for pollinating one-sixth of flowering plants in the world, and approximately 75 percent of the fruits, nuts, and vegetables grown in the United States. We have bees to thank for an estimated one-third of food and beverages. And, most importantly, many of the plants that they help to pollinate are critical links in the food chain of present-day society, making up a large portion of livestock feed. Certainly with an exponentially increasing population of more than seven billion humans, humanity as we know it would struggle to survive in a world without bees.
Through their role as pollinators, they also contribute to ecosystem stability by maintaining genetic variation in the plant community. Cross-pollination is the only way to constantly mix genes for a plant, creating genetically varied offspring. Not only does this contribute to biodiversity, it also helps plants evolve and adapt to environmental changes. The more genetic diversity in a species, the greater the chance of some offspring surviving any new environmental conditions they may face.
Quite a few factors play into bee deaths. A particularly severe problem that has worsened in the last decade is Colony Collapse Disorder (CCD) in honey bee hives. CCD results in a colony in which most of the adult bees either die or abandon their hive, usually leaving behind a live queen and immature bees. It is not the only cause of losses, but it is certainly one of the major contributing factors of the increased rate of commercial losses beginning in 2006. Because of CCD, the number of honey bee hives in the U.S. is at its lowest point in 50 years.
Some scientists speculate that climate change may also contribute to losses. Honey bees, like many pollinators, hibernate during the winter. The rise in global temperatures over the past two centuries can alter the time frame during which some species of flowering plants bloom. This can be problematic if the flowers that provide food for bees have already bloomed by the time they wake from hibernation.
Similarly, when flowers bloom before bees come out of hibernation, it is much more difficult for them to reproduce because the bees are not helping them to cross-pollinate. And with earlier blooming often comes earlier declining of flowers, which hurts those species that need a supply of pollen and nectar throughout the year.
In recent years, flower rich meadows and wildflower populations have been destroyed to make way for commercial farmland or development projects, causing the bees to suffer tremendous losses because they no longer have the food to sustain their populations.
Destruction of grasslands due to farming, urban development, and changes in climate is a growing trend across the globe. The U.K. has lost an estimated 97 percent of its flower rich grasslands in the last 70 years, largely to make way for farmland. It is no surprise that a number of bumblebee species in the U.K. have gone extinct in the past few decades.
The current drought in California has also contributed to habitat loss, since less rain means fewer flowers. California’s almond orchards and other cash crops rely heavily on bees for cross-pollination. With the drought, these bees may only have access to these almond plants because many of these farms do not provide a variety of plants for them pollinate. The pollen and nectar from almond plants is not as nutritious as that of other plants, and relying on these crops alone is not healthy for the bees.
Stress from Commercial Beekeeping
There are several ways in which certain commercial beekeeping practices are thought to cause CCD. Continuing with the almond example, there is a high demand for bees to pollinate California’s almond crop in the late winter. This is before bees normally repopulate, so this kind of stress on smaller populations of bees that are already struggling to make it through the winter can be problematic.
The agri-industry’s drive to maximize profits has also hurt bees by focusing on money-making crops like corn and soybeans, which are not as healthy for bees as plants that they are drawn to in nature, such as alfalfa and clover fields. Bees need high-quality pollen in the fall to produce offspring that can survive through winter, and without access to pollen and flowers that are healthy for bees, winter losses will inevitably be higher.
Another problem is when beekeepers lease their colonies for pollination. Many of the crops that bees are leased out to pollinate, almonds included, cause nutritional stress for them. The transportation and new environments also cause stress on the colonies.
And finally, the chemicals that beekeepers use to treat for pests and parasites in bee colonies can sometimes negatively affect the bees. Some of these chemicals, such as fluvalinate, which targets varroa mites in honey bee colonies, can accumulate in comb wax and harms worker bees over time.
Pesticides are a major cause of colony loss. One study found 35 different pesticides as well as high levels of fungicides in the pollen collected by bees in five U.S. states. Some of these samples contained lethal levels of these chemicals. Another study found that certain fungicides made bees up to three times more susceptible to infection by the parasite Nosema ceranae, which may also contribute to CCD.
One potentially lethal class of pesticides is known as neonicotinoids. These were first registered for use in the mid-1990s, and are now used on farm crops, ornamental landscape plants and trees. Neonicotinoids are systemic chemicals, meaning that they are absorbed by plants and transferred through the vascular system, making the plants themselves toxic to insects.
Neonicotinoids are long-lasting, both in the plants themselves and in the soil. Even when neonicotinoids are applied outside of a plant’s bloom period, the harmful effects will remain present in the pollen and nectar of the plant for long periods of time.
Neonicotinoids are known to poison entire colonies, not just individual bees. Bees not only feed on the contaminated nectar, but they bring pollen full of neonicotinoids back to the hive. These pesticides affect the central nervous system of the bees. At their lethal dosage, neonicotinoids are thought to block nerve endings, causing paralysis and eventual starvation.
Lack of Genetic Diversity
Like the plants they pollinate, bees rely on genetic variation in order to adapt to environmental changes. Honey bee colonies contain large numbers of related bees that live in high densities and exchange food by mouth—all perfect conditions for the development and spread of disease. They do have behavioral and immune system defenses against disease, but those are only effective if there is a high level of genetic variation within colonies. If all worker bees are the same, they may be more vulnerable to certain pathogens because they all lack the immune system and behavioral responses capable of fighting those pathogens.
There are several causes behind the lack of genetic variation in bees. Because the varroa mite has wiped out many of the feral bees, some scientists suggest that it is even more likely that bees will mate with close relatives in the colony. Additionally, the falling population of bees means that there are fewer drones overall for queens to mate with. Finally, the frequent transport of bees to new locations may play a role, as those bees do not have a chance to adapt to local pathogens and conditions in their new environments.
So what would happen if bees went extinct? The most obvious answer is that there would be a lot less food in terms of variety and quantity. Since an estimated one-third of all food eaten by humans is dependent on bee pollination, an ever-growing human population of more than seven billion would certainly struggle to survive. Fruits, vegetables, and nuts would be scarce, and humans would have to find a new source of livestock feed in order to keep up our addiction to meat and dairy products.
Not only would flowering plants be at risk, but ecosystems dependent on bees for maintaining biodiversity would suffer, making some organisms more susceptible to disease and, eventually, extinction.
It does not look as though honey bees will be going completely extinct in the near future, but with the current rate of colony death, we may soon see a devastating impact on the genetic diversity and sustainability of ecosystems on a global scale.
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