AasandOctober 5, 2018
Factors Contributing to the Decline of Bees
As the title of this paper suggests, the following pages will address the issues concerning bees and why the number of bees is declining. I began this paper hoping the issue would be cause/effect or problem/solution but through my research I quickly discovered that was not the situation. Bees hold a great deal of significance to the lives of both plants and consumers through pollination and food production. However, bees are threatened by multiple factors that all contribute to their decline. Factors such as disease, parasites, Colony Collapse Disorder, and agriculture-related events all effect these important pollinators.
Plants that do not self-pollinate rely on cross pollination, which is typically seen in wind pollination or animal pollination, if not a combination of both. Many grains are able to reproduce by wind pollination, but most fruits and vegetables, as well as fodder crops for livestock, rely on animal pollination. The Greenpeace Science Laboratory at Exeter University (2013) reported that about one third of plants, including crops consumed by humans, depend mainly or entirely on animal pollination. Animal pollination occurs naturally and accidentally by various animals or insects. Some of these creatures include butterflies, bees, and hummingbirds. When an animal pollinator goes to a flowering plant to feed, some of the pollen from that plant becomes stuck to them. When they move to a different plant of the same variety to feed, some of that pollen falls off and ultimately leads to pollination of the plant. In addition, there are some plants that are pollinated in other ways, but benefit from animal pollination. Professor Alexandra-Maria Klein, the Department Head Chair of Nature Conservation and Landscape Ecology at the University of Freiburg notes that of the world’s leading crops, about 75% produce more with animal pollination in conjunction with other pollination methods than non-animal pollination alone (as cited in Tirado et al., 2013, p. 14). To put it into perspective, without pollinators, there would be about 30% less plants around the globe, and the remaining plants would be less abundant and lacking in variety. As the human population continues to rapidly increase, scarcity of food cannot be afforded. Animal pollination plays a significant role in the production of plant-based foods and as bees are among the most prolific of animal pollinators, they also play a significant role in the production of plant-based foods.
Senior Research Associate at University of Bern in Switzerland Geoffrey R. Williams, et al., concluded that honeybees are “valuable animal pollinators to agriculture because they can be easily maintained and transported to pollinator-dependent crops.” (Williams, 2010). Honeybee hives can be managed and strategically utilized to pollinate commercial crops that produce food. Because bee pollination increases crop yield, large numbers of portable hives are often taken to fields and released to freely pollinate that specific crop. Once the time period for pollination has ended, the hives can be transferred to another field of crops that are then ready for pollination. This practice is beneficial to agriculture and food production, but is ultimately harmful to bees. This issue will be further explained in a later paragraph.
The Food and Agriculture Organization of the United Nations (FAO) estimates that of the 100 leading crop species which provide about 90% of food, 71 are pollinated by bees (as cited in Tirado et al., 2013, p.14; Kluser et al., 2010, p. 1). Without bees’ pollination of crops, crop production would show a significant decrease and world-wide food shortage could be the result. As the world population continues to grow, the need for food increases as well. James Owen from National Geographic News reported that currently about 40% of the Earth’s land is used for agriculture, which is an increase from the 7% of land in 1700 (Owen, 2005). To compensate for the increased production of food and crops, the population of pollinators should have increased as well. As Klein, along with Dr. Marcelo Aizen, pollination researcher and author of over 150 articles, Lucas Alejandro Garibaldi, Scientific Advisor at the Food and Agriculture Organization of the United Nations, and Professor Stuart A. Cunningham point out: in the past 50 years, the amount of managed honey bee hives has increased approximately 45%. However, the amount of crops that require insect pollination has increased about 300% in the same time period (as cited in Aizen ; Harder, 2009, p. 915; Spivak, Mader, Vaughan ; Euliss, 2011, p. 34; Williams et al., 2010, p. 845). That 45% increases would appear significant, but it is minuscule compared to the increased demand for insect pollination. And while the amount of managed hives has increased, those sources failed to point out the change in the overall number of bees. Despite that 45% increase seen in the last five decades, the population of bees, both commercially managed and wild, is currently decreasing. As pointed out before, bees are crucial pollinators to crops and play an important role in global food production. So the question is, what is causing the declining bee population?
There are numerous factors contributing to this decline, some natural and less manageable, and some quite complicated but with possible solutions. Some of the more minor and uncontrollable issues are disease, parasites and Colony Collapse Disorder (CCD). Most diseases and parasites are invasive species that must be fought through natural adaption of the bees. One such parasite is an external mite, Varroa destructor. This parasite feeds on bees’ blood and can spread from hive to hive, and in turn spread other diseases to neighboring hives (Tirado et al., 2013). Parasites such as Varroa destructor often do not directly kill bees. However, bees that are already weakened by parasites or illness become more susceptible to other factors, such as CCD, which will kill bees and destroy entire hives. CCD is a disorder in which large numbers of adult worker bees leave the hive to die and there are not enough remaining worker bees to maintain the queen, larvae, and hive. This unexplained disorder ultimately leads to the collapse of the bee colony, hence the name “Colony Collapse Disorder” (Spivak et al., 2011). Aside from those contributing factors, farming and agriculture practices seem to pose the largest threat to honeybees. Specific farming related factors include monoculture farming, destruction of habitat and nesting area, and the widespread use of insecticides.
Bees, like most other living species, thrive on a varied diet, rather than consuming the same food source repeatedly. The main source of food and protein for bees is pollen. For optimum health, it is best for bees to collect pollen from a variety of flowering plants. However, their ability to do this, and ultimately their ability to be as healthy as possible, is often inhibited by monoculture farming. Monoculture farming is the growing of a single crop at one time, over a large area of land. This becomes an issue for bees because in monoculture settings, there is only one type of flower to get their pollen from, which limits the amount of diet diversity the bees have access to. Not only that, but crops flower for only a short amount of time compared to the length of the season. This in effect provides nearby hives with a surplus of food for a short period of time, then limited pollen options when that particular crop is no longer in the flowering part of its life cycle. After the crops in monoculture farming have flowered, bees have limited food. As a result, the worker bees are sometimes unable to feed and maintain the hive, which can lead to starvation of colonies. In addition to pollen availability, Claire Kremen, conservation biologist and professor at University of California, and Aizen, (2007) examined how agriculture factors such as tillage, irrigation, and the clearing of woody vegetation destroys the nesting sites of pollinators, including bees (as cited in Tirado et al., 2013, p. 26). When 40% of land is used for agriculture, such practices that are involved with farming threaten the habitats of bees and limits available nesting areas. At the thought of habitat destruction, most often people think of far away rainforests. However, habitat destruction on a smaller but equally important scale is happening all over North America and bees are one of the species suffering the effects of it. As the agricultural business and demand for crops grows, so does the adverse effects of it on bees and other pollinators.
While those factors undoubtedly contribute to the decline in bee population, another agricultural practice, the use of insecticides, is possibly the most problematic issue to bees. Insecticides are a “particular class of pesticide specifically designed to kill insect pests” and therefore “pose the most direct risk to pollinators” (Tirado et al., 2013). As briefly mentioned before, bees that suffer from parasites or sickness can become more susceptible to other issues. In turn, the same can happen when bees are exposed to insecticides. It is in a way a cycle of tragedy. Bees suffering from disease and parasites and more likely to be affected by insecticides, and bees weakened by insecticide exposure are an easy target for disease and parasites. Maryann Frazier, Chris Mullin, Jim Frazier and Sara Ashcraft from Department of Entomology at Penn State University became aware that “pesticides may affect bees at sublethal levels, not killing them outright, but rather impairing their behaviors or their ability to fight off infections” during a 2007 study of pesticides in pollen and honeybee hives (Frazier, Mullin, Frazier & Ashcraft, 2008). Not only do insecticides weaken bees, but they also damage their ability to function normally.
One variety of insecticides that affects bees at a sublethal level is Neonicotinoids. The report, “How Neonicotinoids can Kill Bees” from the Xerces Society for invertebrate conservation, it is explained that unlike other pesticides, which are topically applied to crops, Neonicotinoids are systematic insecticides. This type of insecticide is typically applied as a coating to the seeds before planting, which is a potential disaster to pollinators. The insecticide spreads throughout the system of the treated plant as it grows, including the pollen and nectar, which is consumed by bees. Topical insecticides remain on the surface of the plants for a limited amount of time, and pose less risk to bees. Neonicotinoids remain present throughout the duration of the crops’ life cycle, from seed to harvest. Currently Neonicotinoids are the most widely used group of insecticides in 3329940182880the world (Hopwood et al., 2016). While the use of Neonicotinoids was introduced in the 1980s, their use did not become popular until the early 2000s as shown in the figure to the right, (Hopwood et al., 2016) and steadily increased in the last decade as more varieties were created. The image shows the estimated annual agricultural use of Neonicotinoids in the United States between the years 1994 and 2014. While different colors depict different types of Neonicotinoids, the graph overall shows the increased use of Neonicotinoids in general. The graph shows a quite obvious trend in increased use of Neonicotinoids and suggests that the growth will continue.
As this particular type of insecticide gains popularity, the noticeable effects in bees also increases as a result. “Honey bees exposed to sublethal levels of neonicotinoids can experience problems with light and navigation, reduced taste sensitivity, and slower learning of new tasks, all of which impact foraging ability and hive productivity,” (Hopwood et al., 2016, p. vii). Although bees are often exposed to low amounts of the poison and do not immediately die, the effects are destructive and ultimately can cause death. Bees are complex and community creatures. They rely on their natural instincts and the functionality of the entire hive to survive. If some of the bees in a hive are even minimally impaired by the effects of Neonicotinoids, the entire hive could suffer the consequences. For example, many studies have found that cognitive abilities, communication, navigation and mobility of bees are all impaired due to the exposure to insecticides (Tirado et al., 2013; Hopwood et al., 2016). That damage could cause bees to not be able to communicate with one another about the location of food, or individuals to become lost while foraging and not return to the hive. Without worker bees returning to the hive, there will not be enough bees to maintain the needs of the queen and the larvae, which could in turn lead to the collapse of the colony.
In addition to all the adverse effects of Neonicotinoids, bees have no way to avoid contact with the insecticide. As mentioned before, Neonicotinoids are systematic insecticides, meaning they stay present for the plant’s life cycle. This is becoming even more of an issue because of the increasing popularity of the insectide. Not only are Neonicotinoids a now wide-spread and popular insecticide, but a recent study found that bees are incapable of detecting it in their food. Sébastien Kessler, reasearch associate, Geraldine A. Wright, professor of insect neuroethology, Kerry L. Simcock, Sophie Derveau, and Samantha Softley at Newcastle University of England, in collaboration with Jessica Mitchell, Erin Jo Tiedeken, research biologist, and Jane C. Stout, professor at Trinity College, Dublin, conducted a study involving Neonicotinoids and bees. They gave bees the option to feed from two sucrose solutions. One sucrose solution contained low doses of Neonicotinoids, about the amount that would be found in the nectar of a flower treated with the insecticide, and one control sucrose solution. The results showed that bees were not repelled by the Neonicotinoid solution, and were in fact unable to detect the low amount which shows that “…bees cannot control their exposure to neonicotinoids in food and implies that treating flowering crops with neonicotinoids presents a significant hazard to foraging bees” (Kessler et al., 2015). If bees are unable to avoid a harmful substance because they are unaware of it, they will inevitably consume it. If they inevitably consume Neonicotinoids, the negative consequences are also unavoidable, leading Neonicotinoids to be partly blamed for the decline in bee population.
To conclude, the number of bees is declining for a multitude of reasons. As animal pollinators, bees hold an incredibly important role in the production of food. Without them, the planet would experience a major decrease in plant life and plant variety, and the availability of food would decrease as a result. Despite bees’ role in pollination and food production, they are being harmed by the production of food in the agricultural and farming communities. That harm can be accredited to monoculture farming, habitat destruction due to increased farm land, and largely the wide-spread use of insecticides, particularly the systematic insecticide Neonicotinoids. In addition to the adverse effects farming brings to bees, their numbers are also suffering from disease, parasites, and the unexplained dilemma of Colony Collapse Disorder. There is no single factor to blame for the decreasing bee population. Rather, the cause of this global issue is due to a combination of many factors and those factors working in conjunction have led to the unfortunate pattern of bee death.
Aizen, M. A., ; Harder, L. D., (2009). The Global Stock of Domesticated Honey Bees is
Growing Slower than Agricultural Demand for Pollination. Current Biology, 19(11), 915-918. Retrieved from https://ac.els-cdn.com/S0960982209009828/1-s2.0-S0960982209009828-main.pdf?_tid=eeed9b63-cc25-4c29-8add-97cadc90ba81;acdnat=1537551796_c2bff4b54a2060b858fa54646576bd99. Citation.
Summary This article focuses on the history of the declining bee population and the world’s dependence on bees and other pollinators. Reflection Because this article has a slightly different main focus than the other articles I have looked at, this one will be helpful for the introduction portion of my research paper. I plan to explain the importance of bees and discuss their disappearance, and this article will provide useful information for that. Evaluation This article was written for Current Biology by senior researcher and biologist Marcelo A. Aizen, and University of Calgary Professor of Biological Sciences Lawrence D. Harder. It is a reliable and useful resource.
Frazier, M., Mullin, C., Frazier, J., Ashcraft, S. (2008). What Have Pesticides Got to Do With It? Retrieved from HYPERLINK “https://www.researchgate.net/profile/Jim_Frazier/publication/
Summary This article provides a brief overview of the issue of the declining bee population. It then focuses on the issue of pesticide use and explains the results of research conducted involving the levels of pesticides found in various parts of beehives. Reflection Because this is a primary source (it gives data and results from research), it will be useful for explaining the factor of pesticides and insecticides in my paper. Evaluation Along with references several reliable articles and sources, the authors of this scholarly article are from Department of Entomology at Penn State University, which contributes to the reliability of this source.
Hopwood, J., A. Code, M. Vaughan, D. Biddinger, M. Shepherd, S. H. Black, E. Lee-Mäder, and C. Mazzacano. (2016). How Neonicotinoids Can Kill Bees: The Science Behind the Role These Insecticides Play in Harming Bees. 2nd Ed. 76 pp. Retrieved from http://www.xerces.org/wp-content/uploads/2016/10/HowNeonicsCanKillBees_Xerces Society_Nov2016.pdf. Citation.
Summary This is a very lengthy article focusing on Neonicotinoids. Like most other articles, this one briefly explains the importance of bees. It then goes into all the details involving insecticides and bees, specifically neonicotinoids. The article explains what neonicotinoids are, how bees are exposed to them, the effects, and potential solutions. Reflection This source is helpful because from my research I believe that neonicotinoids are the most harmful insecticides to pollinators. This article gives good information on that specific insecticide and has some graphs and images that could be useful for me. Evaluation This article was written by a team of researchers and scientists at the Xerces Society for Invertebrate Conservation. It is an organization dedicated to the preservation of many species, including bees.
Kessler, S., Tiedeken, E. J., Simcock, K. L., Derveau, S., Mitchell, J., Softley, S., … Wright, G. A. (2015). Bees Prefer Foods Containing Neonicotinoid Pesticides. Nature (521)74–76.
Retrieved from http://web.a.ebscohost.com.ezproxy.library.pfw.edu/ehost/pdfviewer/ pdfviewer?vid=4&sid=b4cc40d5-7aa4-4fe2-8365-c25503e7af4f%40sessionmgr4006. doi:10.1038/nature14414. Citation.
Summary This article from the periodical Nature describes all use of neonicotinoids and the effects they have on bees. It also explains the results of a study conducted that determined that bees cannot detect the insecticide in pollen and therefore are at increased risk of the negative effects. Reflection I will be able to use this source in my paper by explaining the study. Using a direct source like this will add to the credibility of my paper. Evaluation This is a very reliable source. All the authors are all successful or experts in their fields. Sébastien Kessler, reasearch associate, Geraldine A. Wright, professor of insect neuroethology, Kerry L. Simcock, Sophie Derveau, and Samantha Softley at Newcastle University of England, Jessica Mitchell, Erin Jo Tiedeken, research biologist, and Jane C. Stout, professor at Trinity College, Dublin all contributed to this article that was published for the International Journal of Science, Nature.
Kluser, S., et al, (2010). Global Bee Colony Disorders and Other Threats to Insect Pollinators. 16
pp. Retrieved from https://europa.eu/capacity4dev/unep/document/global-bee-colony-disorders-and-other-threats-insect-pollinators. Citation.
Summary This is another good article that explains why pollinators are important and goes into detail of potential causes and threats. Reflection I should be able to pull some good statistics from this article, and it gave me some new ideas to research. Evaluation This article was published by the United Nations Environmental Programme, an organization that pushes to improve and protect the global environment.
Owen, J., (2005, December 9). Farming Claims Almost Half Earth’s Land, New Maps Show. National Geographic News. Retrieved from https://news.nationalgeographic.com/news/2005/12/1209_051209_crops_map.html. Citation.
Summary This article explains how much of the earth’s land is used for farming and how that is projected to grow as the population grows. Reflection This source will be useful because I can use it to explain my point of just how necessary pollinators are. Without pollinators, how would all that farmland be pollinated, and how would that affect our food supply? Evaluation This article was written for National Geographic and author James Owen uses many reliable sources to explain his main points.
Spivak, M., Mader, E., Vaughan, M., Euliss, N. H. (2011). The Plight of the
Bees. Environmental Science & Technology, 45(1), 34–38. Retrieved from https://pdfs.semanticscholar.org/780b/df12fb876ec647c9755a68f930f5bff180db.pdf.
Summary The article discusses the decline of bee populations and its causes. It explains the importance of bees economically in agriculture, monoculture crops, and different issues the honeybees face, including CCD, nutrition, and habitat. Reflection I like that this article gives a good summary of the overall issue and mentions detail about other pollinators. Evaluation This is a reliable source. It is from the scholarly journal, Environmental Science & Technology, and the authors used about 50 sources to compile the 4 pages.
Tirado, R., Simon, G., Johnston, P. (2013). Bees in Decline. Greenpeace Laboratories. 46 pp.
Retrieved from http://www.greenpeace.org/switzerland/Global/international/publications/ agriculture /2013/BeesInDecline.pdf. Citation.
Summary This article goes into detail about the many different factors affecting the health of pollinators, and suggests which ones are the most severe. It also provides many helpful statistics and visuals. Additionally it includes suggested solutions. Reflection I think this will be an extremely helpful source because it goes into detail about essentially all the points I wanted to address in this paper, and should be a good jumping off point for the solution aspect of the paper (if I chose to take that approach). Evaluation This technical report was published by a group of scientists at Greenpeace Research Laboratories.
Williams, G. R., Tarpy, D.R., vanEngelsdorp, D., Chauzat, M. P., Cox-Foster, D. L., Delaplane, K. S., … Shulter, D. (2010). Colony Collapse Disorder in Context. Bioessays 32 (10), 845-846. Retrieved from https://onlinelibrary.wiley.com/doi/epdf/10.1002/
Summary This article explains the necessity of bees and the issue of Colony Collapse Disorder. It doesn’t blame CCD for the declining bee population, but suggests the idea that a combination of factors is to blame and some of those factors contribute to the severity of CCD. Reflection While short, this article provides good information relating to my topic and will be a useful resource. Evaluation Most of the authors of this article are from the Department of Entomology at Pennsylvania State. Other authors include Peter Neumann from the Swiss Bee Research Centre, ecotoxicologist Richard E. L. Roger, and Marie-Pierre Chauzat from the French Food Safety Agency (AFSSA).