Contents

Introduction

Apis mellifera (western honeybee, European honeybee) is a key pollinator for agriculture in the United States as it is reported to be the bee species that pollinates the greatest variety of the crop species[1]. Therefore, a continuous decline in the western honeybee population in recent years in North America is especially alerting. This wiki page will not only highlight the importance of the western honeybees but also introduce the impact of the decline in western honeybee population to our society, economy, and environment. Furthermore, this page introduces several potential causes such as a parasitic mite, Varroa destructor [2] that leads to the population decline as well as some additional responses that may be detrimental to the species.

Roles of Western Honeybees

As small as they are, honeybees play a crucial part in everyone’s daily lives. From beeswax, honey cosmetics, health benefits, etc., they also provide pollination services for food for humans, are part of the food chain which can help maintain biodiversity, and help with the pollination of wildflowers. The US holds one of the world’s most active market for pollination services by honeybees [3]. Apis mellifera, also known as the western honeybees are one of the key players in the agricultural industry in the US. Studies have shown that agricultural industries that rely on pollination by bees have gone up approximately 30% compared to those that do not. [3].Another study has also shown that “reduced agricultural yields and fruit deformation often results from a lack of pollination, [and] can also determine fruit and seed quality and nutrient content” [4][5].

There is a tradeoff between the increased quality of agriculture and the pollination services the western honeybees provide [3]. “Apis mellifera are used routinely to pollinate apple and pear orchards” [5].A study conducted in Argentina in pear and apple orchards and their relationships they shared with Apis mellifera found to have increased number of "fruits/tree and sugar content as well as overall farmer’s profit for apples" [5]. In this particular area, crop pollination was only done by one species (Apis mellifera), meaning that their decline in population would be detrimental.

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Causes of Population Decline

The population decline of Apis mellifera is not only affected by a combination of Varroa destructor and viruses, but also nutrition deficiency, starvation, colony collapse disorder, genetically modified crops, reduction of genetic variability, poor queens and climate change. Female Varroa mites along with viruses can be detrimental to honeybees, especially since the virus easily enables the Varroa mite to attack its host. It enters the hemolymph, which is the equivalent to blood in humans in invertebrates, and consequences include a decrease in body weight which would interfere with organ development and deformed wings which in turn can affect flight duration. Colony Collapse Disorder (CCD) can also be a consequence due to the Varroa mite [2][6].

There are no known treatments that are 100% effective against the Varroa mites and viruses and eradicate them from Apis mellifera. Treatments used against these mites would also kill the susceptible honeybees and give more resistance and time for the mites to adapt to these treatments. Over time the Varroa mites will develop even stronger resistance to the treatments and pass it down to their offsprings [6]. It was also stated by another, that without periodic treatment of Varroa, the colonies of most honeybees in temperate climates are susceptible to fail within two to three years [7].

Nutrient deficiency occurs when there are no crops available that provide the nutrients needed for the western honeybees. An example occurs in the United States Northern Great Plains, which have an influence over the health and nutrients of western honeybees located in that area. Pollen collected and stored in hives are the primary source of nutrition that is unavailable to them over winter [3]. Today up to 20% of losses are due to winter mortality [6]. Along with nutrient deficiency which causes honeybee populations to decline, starvation, which occurs when the honeybees cannot find any food for their survival or when there are poor forage conditions also affects the population. With the combination of starvation and nutrient deficiency, this makes Apis mellifera more susceptible to various viruses and Varroa mites [6].

Another factor that plays a role in the population decline of western honeybees can be found in pesticides. One of the reasons why genetically modified organisms (GMO) was created was to reduce the use of pesticides. However, over the years, many organisms have learned to overcome and adapt to pesticides. A study done in Washington in 1962 concluded that beekeepers lost approximately 3.2% of their bees due to pesticide-mediated bee kills [2].

Lastly, genetic variability of the honey bee colonies can affect the population decline of this species. There are selective pressures on the honey bees that are “influenced by management decisions used to control parasites and diseases, protection against cold temperatures and artificial feeding” [2]. This favors the colonies that were treated compared to those that were forced to adapt and develop natural resistance to diseases. Genetic variability can be lost at an exponential rate if the western honey bees are introduced to a new parasite, pathogen or virus that they have no resistance to. In general, having larger numbers of genetic variability is needed for evolution and adaptation to further better resistance to diseases, pathogens and viruses and overall increase colony fitness [2].    

Social Impacts

Being one of a few widely used honeybees around the world for agriculture, the western honeybee is an essential species for enhancing agriculture productivity [8]. The recent bee colonies decline has affected the honey industry, especially the beekeepers [9]. A symptom that contributes to a large number loss of mature bee with no dead bees around the hives which is being called Colony Collapse Disorder (CCD) has an enormous impact on the beekeeper community in USA [9]. Due to the tremendous yearly loss of the managed bee colonies ranging from 30% to 60% over winter continuously in the past decade, beekeepers are not able to keep up with the decline as the livelihood of the beekeeper community is threaten [10].

As the whole bee industry is affected by the decline in honeybee population, the supporting services that revolve around it  would also experience a negative impact. Transporting beehives has become more common in recent years to satisfy the need of farmers that grow mainly pollinator-dependent crops such as canola [11]. Followed by the decline of honeybee population across north America, trucks that transport beehives become an even less favorable job than before. Not to mention such service has already been suffering from low recruitment rate [11].

On a much larger social scale, the loss of pollinators affects the dynamics of food consumption and supply [12]. Statistics shows that the loss of pollinator will not only jeopardize the overall world food supply, but also will create a deficit in 3 main crop categorizes including fruits and vegetable that have high market value but low storage duration [12]. The report further explains that in some regions, the loss of pollinators will result a shift in consumption and production as consumption will exceed production [12]. Western honeybees are responsible for pollinating a wide range of crops in North America and their decline in population can certainly lead to negative shifts on a much greater scale [12].

Economic Impacts

Before the methods of refining sugar, honey was the only sweetener available which led to the domestication of bees and eventually, the practice of beekeeping [2]. Of the various bee species used for beekeeping, Apis mellifera L. is most used throughout the world due to their high adaptability [2]. Though bees are mostly known for their production of honey, they are also crucial for crop pollination and beeswax production amongst many other bee products.

Honey

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Honey, one of the most commonly used sweetener, has the highest economic importance among all the bee products. In 2007, honey was worth about US$1.25 billion and there about a “58% increase in production since 1961” [2]. Honey produced by canola is most common in Canada; almost 80% of the honey produced comes from canola. [11]. Honey from canola is also in high demand in the US [11]. Especially in areas where there are low yields of produce, honey from canola provides good income [11].

Crop pollination

Though honey provides are large source of income to beekeepers, providing bees to pollinate crops also is a large source of income. As for canola, canola is “90% dependent on honey bees”, though Megachile (leafcutter) are also used alongside these honeybees for pollination [11]. For areas in which pollination is challenging naturally, beekeepers provide bees to companies and contracts between companies, growers, and beekeepers are usual. According to Clay, 10-17 frames of bees cost about $110-$150 [11]. Though how many colonies are in per frame is not stated, Clay also mentioned that about 300,000 colonies pollinated canola, and 80,000 colonies of that amount were used in southern Alberta [11]. Not only do honeybees provide income to beekeepers, but also to the other “players” in the agriculture industry such as the canola seed company and truck drivers. As stated above, canola is very dependent on bees for sexual maturity as the bees transfer pollen. In 2008, 12.6 million tonnes of canola were produced and they were valued at $13 billion and the areas used for canola seed production is expanding, stressing the importance of bees’ role of pollination.

Whereas honeybees play an important role in canola plantations in Canada, mainly in southern Alberta, honeybees play an important role in almond plantations most specifically in California. California produces around 80% of the world’s almonds and 70% of almonds produced in California is exported, “making almonds California’s largest-value agricultural export” [13]. In two decades, California has found that there was a 84.5% increase from around 802,000 hives to 1,480,000 hives required for almond pollination” [13]. Carman states that the average cost for a hive was “$150.79 for almonds, $145.89 for early cherries, and $128.29 for plums” [13]. Like there were contracts between beekeepers and companies, there are contracts used in California as well, usually for more than one type of crop so that beekeepers can take advantage of different bloom periods of different crops [13]. Some other crops that honeybees pollinate are apple, avocado, cherry, kiwi, pear, prunes/plums, alfalfa seed, cucumbers, melons, sunflowers, and vegetable seeds [13]. Of these crops, apples, melons, sunflowers, and alfalfa seeds bloom later, which drive down the cost of the hives as pollination fees are the highest during early bloom as the demand of hives are high. One economic problem that beekeepers face stems from Bee Colony Collapse Disorder (BCCD or CCD). This is when a worker bee leaves the hive and never returns back to the hive. Though many possible factors were found, there is still no one cause of CCD that is widely accepted. Because of CCD, beekeepers, in order not to break their contracts with the farmers, “must replace the lost colonies by purchasing bees to fill the empty hives” [13]. The cost of a hive can cost over $100, which adds to beekeeping costs, almost increasing about half of the cost of almond production [13].

According to Gallai et al., they listed that the “total economic value of pollination worldwide amounted to €153 billion” and this represented “9.5% of the value of the world agricultural production [...] in 2005” [12]. This 9.5% value may be small, but it is due to many different crops which all have different factors being summarized into a single number. Per ton, crops that did not depend on insect pollination was about €151 while those that were dependent on insect pollination was about €761 [12]. With pollinator loss, though it may not decrease the world food supply, it would deplete crops such as fruits and vegetables. It should be noted that bees pollinating certain crops are also important for forage legumes which affect the “value of beef and dairy products” [12]. Despite the decline of honeybees being negative, many do not consider the fact that the market may also take measures to sustain the same production value [12].

Klein et al. on the other hand mention that without honeybees, more specifically, Apis mellifera, there would be a 90% decrease in fruit, seed and nut crop yields [14]. Especially because many crops depend on pollination by honeybees, a loss of honeybees would decrease the crop yield and affect those who consume insect pollination dependent products.

Beeswax

Commercial beeswax is mainly produced western honeybees. Though beeswax is mainly used for wax foundation, beeswax has many other uses such as for cosmetics, pharmaceutical products, candles, etc. [15]. Due to its versatility, beeswax has an economic importance only second to honey. [15].

It was found that the amount of beeswax produced is about 1.5 to 2.5% of the weight of honey produced. In 1991, 1.19 million tonnes of honey were produced, meaning that about 17,850 to 29,750 tonnes of wax were also produced. [15]. Additionally, in 1991, the price per tonne of beeswax was ranged from US$3300 to US$3600 and total value of insect waxes traded was US$23.35 million [15].

Environmental Impacts

Western honeybees are without a doubt the most frequent floral visitor of crops worldwide [16]. Their pollination services are extremely important due to their high contribution as a single genus. The only comparable genus would be the bumblebee genus and even then, the western honeybee doubles the floral visits of bumblebees. As the most important pollinator globally, they take care of a decent proportion of pollination despite their declining populations and increased mortality rates. Wild western honeybee visits have shown no decline in natural habitats and remain stable worldwide. Additionally, western honeybees will repeated visit certain plant species and specialize in certain plants. While specializing, they will synchronize their circadian system with the plant species and be able pollinate more efficiently.

Since more than 75% of cultivated plant species depend on bees, it is very important for the bees to be able to efficiently pollinate[17]. The bees will go under behavioral adaptations which allow them to find certain floral species more easily, learn locations and understand the morphology of the floral species. All of this adaptation allows the bees to be able pollinate the habitat more efficiently and protect the floral species from danger. When bees are not able to adapt to the species, they may repeatedly visit only local plants and therefore damage the floral species and consequently reduce the reproductive success of the floral species due to over pollinating.

The decline in honeybees’ availability for crops is more noticeable than in natural habitats and due to this fact, crops have seen a decrease in yield. Around 87% of global crops depend on the pollination of bees and other wild pollinators but due to the western honeybee’s influence, western honeybees are normally the more reliable and more versatile as an agricultural pollinator humans can control[18]. This leads to a sole reliance on honeybees, and additionally, wild pollinators have been able to enhance the production of some of the crops which is a healthy advantage [18].

We can also see a correlation between the populations of western honeybee, their pollination services, and human’s nutritional diet. Not only do bees help with provisioning services, they also help with regulatory services as they are a multi-ecosystem provider of services [19]. Their bodies serve as biological indicators for trace chemicals in the environment. Impairing chemicals stick to the bee’s body and therefore it is easier for us to track harmful pesticides [20]. Since western honeybees are so widespread, they become an integral part of the tracking process. It is easy to find out if a chemical is harmful to the environment if there are both a high mortality rate amongst western honeybees and chemical residue inside beehive products.

Response to Ameliorate the Decline of Western Honeybees

Consecutive years of increasing western honeybee mortality has been observed in the United States and additional funding and researches were mandated by the US Congress. Such efforts were aimed to find out the contributors of the honeybee decline [9]. Many suspected trans-global pathogen and parasites to be one of many main contributors to the decline [10]. When analyzing the spread of diseases and pests that were related to the decline of honeybee population (not restricted to only western honeybees), it was concluded that the surveyed disease/pest distribution was more likely to be restricted by their geographic elements and climates, rather than human efforts to mitigate the spread. However, the survey was conducted on a country-level and its finding lacked results from within the country. Therefore, the finding becomes less helpful in terms of dealing with the western honeybee population decline [10]. Further into the discussion, roughly 40 industry leaders and scientists in the United States attempted to come up with a solution in response to the western honeybee decline. However, no definitive conclusion was drawn from the meeting [9].

Restoration Methods of Western Honeybee Populations

In response to the rapidly declining western honeybee population, US Department of Agriculture (USDA) initiated an area-wide project administrated by Agricultural Research Service (ARS) and Coordinated Agricultural Project (CAP). Such project initiation was aimed to improve honeybee’s physical condition [9]. Several demonstrative trials were set up across the states and findings were pooled and analyzed by ARS aiming to discover natural resistant bee population to mites and disease [9]. Additionally, it is crucial for structural development to be implemented alongside with experimental results. National Institute for Food and Agriculture (NIFA) were keen to create a bridge that would improve the communication between the results of the research and beekeepers, who were the affected stakeholders of the declining honey bee population. CAP’s project was set to be multi-state, multi-year and also to be integrated to educate affected stakeholders like bee farmers, and such design allowed CAP to determinate the interactive effects of disease agents and environmental change on honeybee’s population, and quickly deliver findings to clients group (bee farmers) to speed up the process of recovering honey bee population.

Importance of Other Wild Pollinators

Though honeybees are the most important pollinators for crop monocultures worldwide, not all crops depend on honeybees nor are they the most efficient [2]. Klein et al. 2007 also mentions that honeybees are not necessarily the most effective pollinators for some crops [14]. Additionally, because not all crops are dependent on honeybees, reduced production of pollinator-dependent crops can be replaced by those that do not require pollinators [2]. Due to the large economic importance of western honeybees, wild bees’ “value for crop pollination has been overlooked” [14]. Though wild bees can “enhance production of some crops, [...] [they] are frequently too sparse to adequately pollinate crops” [14]. Gallai et al. mentions as well that though wild pollinators are important, it is said that there are not enough of wild pollinators “to insure adequate pollination of all crops throughout the year” [12]. However, because of the great importance and commonality of western honeybees, the importance of wild pollinators are often neglected and their decline in population should be taken into note as well.

Conclusion

In conclusion, the western honeybee is a great pollinator as it has the widest range of crop species [1]. However, the western honeybee population has seen a continuous decline in the past few years and does not show any signs of slowing down. Some of the causes might be nutrient deficiency, starvation, colony collapse disorder (CCD), reduction of genetic variability, or climate change. There may be a few reasons behind CCD, one of them being the influence of other insects, mainly the Varroa mite [6][2]. The mites are able to take over the hive and completely destroy the colony. While there are no known permanent treatments to the mite problem, there have been temporary solutions such as pesticides, but due to natural selection, mites be able to adapt with stronger resistances and therefore become immune to said pesticides [6]. Due to climate change, there may also be a drop in available nutrients leading to nutrient deficiency which may have a hand in CCD. In terms of social impact, bees have always helped humans out in agriculture productivity due to their domestication and they do so till this day. [8]. Honey, crop pollination, and beeswax have been an integral part of human economics and each are their own huge industries. Looking at environmental impacts, western honeybees have been known to sync up their circadian body rhythms with plants to allow them to pollinate more efficiently [17]. While there has been no conclusion made in international conferences for solutions with definitive results, there have been area-wide projects aimed to improve honeybee’s physical condition [9].

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