This post is a part of a special series, written by undergraduate students in the University of Rhode Island’s Spring 2018 “Biology and Society” course. This course, taught by Dr. Lindsay Green-Gavrielidis, explores the intersection of biology and society. As part of the course, students wrote blog posts translating scientific articles related to ecology and society for a public audience.
The importance of pollinators
To give a little more insight on how pollinators are important to our lives, the U.S. Department of Agriculture says that over a third of all crop production, including 90 crops from nuts to berries to vegetables require insect pollinators to be made (USDA, 2017). In 2015 Goulson and his colleagues published an article on bee declines that they correlate to stressors such as pesticides, colony collapse disorder, transport of bees, bee diseases, climate change, competition, and mixed stressors. Pesticide exposure impair mechanisms bees use to clean out their systems, and immune responses, which makes bees more prone to parasites.
To help bee populations, we should consider bringing flower-rich habitats into farmlands, using sustainable farming methods, such as reducing pesticides to increase biodiversity, and pushing quarantine measures on bee movements around the world. Although measurements of declines are hard to estimate, human controlled honeybee colonies have suffered a 25% loss of colonies in Europe and a 59% loss in North America, which can be connected to a syndrome referred to as colony collapse disorder. Colony collapse disorder is an issue happening when most worker bees disappear and leave their queen behind along with food and nurse bees to care for the rest of the immature bees along with the rest of the colony. Researchers found out that hives cannot be sustained with the loss of worker bees and would soon decline, which brought this problem to light.
Habitat loss is a major issue bees are facing today. Bees require standard flower resources for their flight season, which can be short for solitary species, or yearlong social species. Bees also require undisturbed nest sites, but the biggest driver of habitat loss is the transition of natural and semi-natural flower rich areas to farmland. In just the 20th century, 97% of flower rich grasslands in the UK were lost, which resulted in major bee declines.
The 3 P’s: Pathogens, parasites, and pesticides
Of the pathogens and diseases that affect bees, deformed wing virus and Nosema ceranae infect both honey and bumblebees. The spread is usually due to the natural long distance traveling of bees. For example, the bee pathogen Varroa has jumped to hosts from Asia to Europe to the Americas and now New Zealand. Disease is also spread by commercial trade of bumblebee colonies, which started in the 1980’s in Europe but now has become much more popular.
Pesticides may be the most controversial aspect of bee loss yet, although they kill pests, they also diminish flowers for pollinators and contribute to making farmland an unlivable space for bees. Additionally they are harmful to the overall health of honeybees and pollinators worldwide. The strongest types of pesticide are “neonicotinoids”, which are neurotoxins that target insect central nervous systems causing death and paralysis. Even a brief exposure to pesticides when bees are still in the larval, or young stage, can affect their adult health. Pesticides prevent colony growth and reduce queen bee production globally by 85% in the honeybees (P. R. Whitehorn, 2012).
Due to the loss of flower-rich habitats to farmland, bees can go months consuming food from only one type of flower. Imagine only eating turnips for an entire month, it can get pretty boring. In California bees are used to pollinate almonds, but some of the pollen contains harmful toxin that the almonds produce naturally, this can cause a decline in the health of the bees. Even though these pesticides are dangerous little is known about certain brands used in this study, therefore, further research is needed.
Bees are transported around the world by agriculture to use as pollinators, and face situations like high temperatures, high levels of CO2 and vibrations, which can cause serious stress to bee colonies. In the future it would be useful to have studies that show how the stress of shipping can impact function and behavior of bee colonies. Competition with native bee populations is another common issue, since we often bring non-native bees to foreign areas, which can reduce the number of native bees in the area.
Climate change can be dangerous for plants that depend on pollinators, like bees, when considering that certain bees might migrate to new areas if the temperature becomes too hot or cold; this is called range shift. This can also result in areas with flowers in need of pollinators without any bees living in areas, and bees living where flowers are not plentiful. Range shifts are seen in butterflies and evidence tells us bees aren’t too far behind them when considering how the lower altitudinal limit of a species of montane bumblebees has moved uphill in Spain. Scientists are now predicting that bumblebee declines will begin at the southern border of their territory because they are poorly adapted to the high temperatures.
Major stressors for bees
Multiple stressors can combine to have a severe impact on bee populations. Certain chemicals and pesticides may not be harmful, but can become deadly if they come into contact with other chemicals in their travels.
Exposure to these chemicals or pesticides can make bees more susceptible to diseases. Even if the chemical that bees come into contact with isn’t dangerous, it could become deadly if the bees aren’t getting enough nutrients. Think about our immune system for example. If we don’t have the proper nutrients, we may be more likely to get sick, as opposed to someone with a strong immune system. Studies to determine how multiple stressors affect bee populations are hard to conduct because these stressors are difficult to control. The good news is that it isn’t hard to make some changes for the sake of our precious bee pollinators, on the flip side it may be expensive for farmers who could potentially lose crops. One of the easiest ways we can act would be to reduce our use of pesticides and other harmful stressors.
Studies in India suggest that bees are also affected by cell phone waves. Andrew Goldsworthy, a UK Imperial College biologist says animals as well as insects use chryptochrome to sense the direction of the earth’s magnetic field and their ability to do this is weakened by the radiation from cell phones and their base stations (Herriman, 2010). Bees are potentially getting lost as they travel back to find their hive due to cell phone signals.
Sustainable pollination for the future
With the addition of more insect-pollinated crops, there is more variety, as well as natural community for bee populations to live in. We should stop focusing on specific pollinators for certain jobs, such as almonds, because if one species is not populated in a specific area, bees will be free to travel and pollinate where they seem fit, and where nature takes them, which will most likely improve crop success. The increased number of bee species can also cushion the impact of climate change, which is another reason it’s crucial to save pollinator communities. Saving natural floral rich farmland is one of the steps we can take to start to help bee communities. This increases pollination and therefore increases foods and other resources that require pollination that we rely heavily on. Education about pollinator health is critical to maintaining bee populations.
Natural nesting sites for bees can be increased by maintaining patches of bare soil and hollow canes for bees to nest in. We should also start considering pesticides a last-resort to ward off pests that will reduce harmful effects on bees, the environment, and farmland. Restriction programs and other laws can help accomplish this. The US Environmental Protection Agency implemented a law in 2017 that helps protect bees from agricultural pesticide spray and dust applications while the bees are under contract for pollination services and advises states on how to develop pollinator protection plans. Additionally we can stop the transfer of foreign bees, parasites, and diseases by improving quarantine controls.
What’s beeing done?
Programs to help bee populations include Bumble Bee Watch in North America and Beewatch in the UK; these programs aim to map bee populations. The USDA Forest Service, the North American Pollinator Protection Campaign, the Pollinator Partnership, Urban Bee Gardens at U.C. Berkeley, and the Xerces Society each supply information to those who want to start gardening for pollinators or improving bee habitat in general (Moisset, 2011). There are many areas that require further research. Further research is needed to count bees and to get better estimates of populations and declines. If we don’t act fast and come up with better ways to establish concrete data on bee populations, who’s to say we are not already experiencing a pollination crisis?
Goulson, D., Nicholls, E., Botias, C., & Rotheray, E. L. (2015). Bee declines driven by combined stress from parasites, pesticides, and lack of flowers. Science, 347(6229), 1255957-1255957. doi:10.1126/science.1255957
Being Serious about Saving Bees. U.S. Department of Agriculture. Retrieved March 19, 2018, from https://www.usda.gov/media/blog/2017/06/20/being-serious-about-saving-bees
Moisset, B., & Buchmann, S. (2011). Bee Basics An Introduction to Our Native Bees . A USDA Forest Service and Pollinator Partnership Publication. Retrieved March 19, 2018, from https://www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5306468.pdf.
Herriman, S. (2010, June 30). Study links bee decline to cell phones. Retrieved March 19, 2018, from http://www.cnn.com/2010/WORLD/europe/06/30/bee.decline.mobile.phones/index.html
R. Whitehorn, S. O’Connor, F. L. Wackers, D. Goulson, Neonicotinoid pesticide reduces bumble bee colony growth and queen production. Science 336, 351–352 (2012).10.1126/science.1215025pmid:22461500 doi:10.1126/science.1215025