Bee decline has been a hot topic for some time now. While many were talking about the phenomenon of colony collapse during the mid-2000s, some have pointed to recent evidence stating that Colony Collapse Disorder (CCD) is no longer a problem, and that honey bees are not as threatened as we once thought. There are also reports from a couple of years ago that shows honey bee colonies have actually increased since CCD was discovered.
But in 2018, beekeepers lost around 40% of their colonies. While CCD may not be a current problem, honey bees – and the 95% of bees that are not honey bees – are indeed declining, and there are many reasons why that is happening.
Study About Bee Decline
A 2019 study, conducted by the National Scientific and Technical Research Council in Buenos Aires, supported its hypothesis of a widespread global decline in bee diversity that began in the 1990s and continues to this day. Since there are a documented 20,000 species of bees in the world, and each belongs to one of seven bee families, the researchers wondered if there were significant differences among the different bee families.
The scientists collected data from the Global Biodiversity Information Facility – along with local and regional reports of wild bee decline – and concluded that there is a generalized decline across six of the seven families and that there was not one specific family that was driving the downward trend. The researchers chose not to include the Stenotritidae family because of its small size, its low number of species (21) and its limited regionality (Australia).
Why Is Bee Decline Happening?
It is not just one thing causing the reduction in bee populations – it is many things, and all of them combined.
Loss of Habitat
It is shocking to learn that since World War II, 97% of wildflower meadows have disappeared. Without enough places to nest and forage, bees can not survive. Bees can not depend only on protected wildlife sites.
There are two major causes of habitat loss: modern farming habits and urban development.
Large farms that take up land to grow a single crop for commercial production have deprived bees of the diverse diet they need. Add to that the loss of natural habitats like trees, ponds, hedgerows, and flower meadows in order to scale the production of commercial crops, and the result is a devastating loss for pollinators.
Urban development, while not inherently bad, can also wipe out natural resources in the process of putting up buildings. Developers should make a concerted effort to include plantings and parks in their plans.
Since changes in climate can affect when plants flower, bees may have difficulty finding food when they need it. Climate change may also impact nesting behaviour and disrupt their emergence from hibernation. If bees emerge when food is not available – either before plants have flowered or after it’s too late – it could alter or even halt their life cycles.
Parasites and Predators
Honey bees seem most susceptible to parasites, especially the varroa mite. Although only 1.2 millimetres in length, this mite is terribly destructive. It violently inserts itself between the honey bee’s exoskeletal plates and releases an enzyme that essentially liquifies the bee. This parasite targets adult bees, larvae, and pupae. Another parasitic mite is the Acarapis woodi. It infests the breathing tubes of honey bees and then feeds on their blood.
Predators are also a danger – especially for bumblebees. They are threatened by badgers, birds, and even spiders. But honey bees must also watch out for bears, skunks, and beetles. And recently, there are reports of an invasion of “murder hornets” that crawl into honey bee hives and rip off the heads of multiple bees.
While pesticides are necessary for reducing the number of crop-destroying insects, they can also harm non-targeted pests like bees. The most deadly class of insecticide is known as neonicotinoids. These chemicals are absorbed by the entire plant, so when bees forage among plants that have been treated, they bring these toxic substances back to their nests and hives, which ultimately impact the health of the colonies.
Because neonicotinoids are so widely used – in over 120 countries worldwide – they can have a profound impact on the bee population. Studies have found that bumblebees are disproportionately affected by neonicotinoids, and are 2-3 times more sensitive to these substances than are honey bees.
It’s also a bitter irony that the fungicide used to manage the varroa mite can cause harm to the bees it aims to protect. A 2007 study found evidence of this fungicide in the bee bread of honey bee colonies.
Disease can impact both adults and developing broods. Some of these diseases can cause paralysis or invade the digestive tracts of honey bees. While controlling disease in the wild is not possible, it is incumbent upon domestic beekeepers to remove sick bees from their hives so that the disease won’t wipe out entire colonies.
Invasive Plant Species
Invasive plant species can impact bee diet when these plants usurp native plant resources. This could ultimately affect bee diet and could even lead to a loss in plant diversity. While the research is inconclusive as to the overall impact of the threat of invasive plants, they could certainly be problematic for particular bee species.
What Is the Biggest Factor in Bee Decline?
Most scientists have come to the conclusion that there is not just one cause of bee decline, and it’s more likely that several factors in combination are contributing to a reduction in bee numbers.
But a recent exploration of the decline of insect species has pointed to habitat loss as the major cause of bee decline. Long-term trends of increased manufacturing, urbanization, and an increase in commercial agriculture have had a profound negative impact on bee survival rates.
Agriculture plays a dominant role in threatening bee species, and it’s not just deforestation and grassland conversions that are creating problems. It is also the trend toward planting only one kind of crop (monoculture), using synthetic fertilizers and pesticides, removal of plants to incorporate mechanization, and altering natural water sources to improve drainage and irrigation.
What Is the Rate of Bee Decline?
A study published in the journal, Biological Conservation, entitled “Worldwide Decline of the Entomofauna: A Review of its Drivers” aimed to collect data on threats to insects across the globe. Information about threats specific to bees is shown in the table below:
|Taxon||Declining (%)||Threatened (%)||Annual Species Declines (%)||Extinction Rate (%)|
Proportion of declining and threatened species per taxa (published April 2019)
Why Are Some Countries Experiencing More Bee Decline Than Others?
The challenge in determining where bee decline is most prevalent is the disproportional number of records available in certain regions of the world. North America and Europe have kept the greatest number of records, and so it makes sense that it appears the largest decline in bee species is occurring in those regions.
While there is not one particular country or region contributing the most to bee decline, there are records that indicate when specific regions have shown the biggest decline.
In North America (including Central America and the Caribbean) the biggest decline thus far occurred between 1990 and 2000. Europe, however, shows two different periods of decline – one during the 1970s and 1980s and the other between 2000 and 2010.
Africa’s records show a continuous decline starting in the 1990s, and Asia’s drop-off began two or three decades before that. South America hasn’t kept the best records, but there is evidence that the continent has also experienced decreases during the last twenty years.
Even though data availability makes it difficult to point to one area as a hotspot for bee decline, evidence shows that bee species are declining on nearly every continent.
What Effect Is Bee Decline Having on Our Society and Humans Needs and Lives?
There is a common saying consumers come across when reading about the impact of bee decline on our health and well-being: “Pollinators are responsible for one out of every three bites of food we eat.” That may sound like hyperbole or a click-bait headline, but it is estimated that pollinators contribute to 35% of global food production.
Further estimates state that if pollinators didn’t exist, there would be a drop in global supplies of fruit (23% decline), vegetables (16%), and nuts/seeds (22%). While it may be a dramatic illustration – and we are not at the stage where all pollinators are becoming extinct – the decline of pollinating insects could have deleterious effects on human health and nutrition worldwide.
Using the most extreme model of pollinator absence, researchers have been able to estimate how vitamin deficiencies – as a direct result of pollinator decline – would impact global health:
- 71 million people would become Vitamin A-deficient in low-income countries, and an additional 2.2 billion who are already not getting enough of the vitamin would be at greater risk.
- 173 million people could become deficient in folic acid, and there are an additional 1.23 billion who are already deficient.
- The risk of noncommunicable diseases (cancer, diabetes, heart disease) and malnutrition-related diseases could increase by 1.42 million.
But even using less severe models, the effects of pollinator loss are troubling:
- A 75% loss of pollination would result in an estimated 1.05 million extra deaths per year.
- A 50% loss of pollination could mean 700,000 additional deaths per year.
The regions most at risk include sub-Saharan Africa, south and southeast Asia, and central and eastern Europe.
But it is not only fruits, vegetables, and nuts/seeds that would be impacted by the loss of pollinators. There are plants consumed by animals (e.g. alfalfa) that, if in short supply due to lack of pollination, would lead to a reduction in the quantity of meat and dairy that’s available for human consumption.
Plants are also used in making pharmaceuticals, and we can not forget plants’ role in removing carbon dioxide from the atmosphere. It’s hard to imagine how human society could continue without the pollinated plants that allow us to breathe, eat healthfully, and manage a number of deadly diseases.
Of course, not all plants are bee-pollinated, and some are not even reliant on insects for pollination. Some plants are wind-pollinated and others are self-pollinating. Still, the loss of plants that are bee-pollinated would cause a chain-reaction of environmental disturbances that would be very difficult to overcome.
The Debate Regarding Bee Decline
It seems that because it is not easy to point to one specific reason why bee populations are declining, some publishers work to discredit the theory that bees are endangered. These organizations accuse the media of trying to scare people into believing there is a real threat to bees and hive health.
The most common approach to denying there’s a problem is to point to the earlier uproar about Colony Collapse Disorder and to show recent trends in the increasing number of colonies – as if to say that CCD was manufactured strictly to hurt the agriculture industry due to its use of pesticides. These outlets find experts who will cast doubt on existing theory, as in the case where a plant pathologist claimed that it was not pesticides or insecticides that caused the collapse of colonies, but rather diseases or parasites.
There is also an effort by deniers to brush off the threat of monocultures in reducing the variety of plant and floral resources. Instead of responding to the problems monocultures pose for pollinators, they instead point to the need to keep the food supply abundant and affordable. Moving away from monoculture would be less efficient, they say, and produce lower yields.
Their biggest weapon, though, is to state that the honey bee is not on the endangered species list, and that is why people shouldn’t worry about these bees becoming extinct. Efforts to cherry-pick data to prove their points may, at first, seem convincing. But as discussed above, there are multiple factors synergistically working to pose a threat to bee populations. While they are correct in saying individuals and larger community groups should plant more gardens to save the bees, to deny that pesticides or changes in land use are a viable threat is irresponsible and self-serving.
The majority of scientists have concluded that bee populations are declining, and have produced volumes of evidence to back up their claims. It’s important to unearth the motivations behind the cause to discredit their work.