Causes and Impacts of the Decline of Pollinators

 Pollinators are a crucial contributor to our food supply and natural resources. They consist of animals from all walks of life, though most pollinators are insects. Of the 250,000 species of plants on Earth, 88.7% of them are angiosperm plants. This means that they are flowering plants that require some form of pollination. It is estimated that roughly 90% of all angiosperm plants are pollinated by animals. Of these animal pollinators, 99% of them are insects (Sasaki & Hoshiba, 2008, p. s16).  These insects are responsible for pollinating crops all throughout the United States. Although the largest yielded crops in the US are grains like corn and are wind pollinated, many other need help from insects. These include fruits, berries and some vegetables. Many of these crops are pollinated by “managed pollinators”. Managed pollinators are insects that are raised and taken care of by humans, such as the Apis mellifera known as the Honey Bee. On the contrary, wild pollinators are pollinators that do not require any support from humans. In Michigan, blueberry farms require extensive help from bee pollinators. In a 2010 publication by Rufus Isaacs and Anna K. Kirk, the impact of wild and managed bees on small and large blueberry fields was studied. It was found that smaller fields were mostly pollinated by wild bees at around 58%. While larger fields were pollinated by managed bees at about 97%. Although wild bees may dominate small farms, it is estimated that they only contribute to 12% of all pollination on Michigan’s blueberry farms (Isaacs & Kirk, 2010). Unfortunately, both groups are on the decline. The reason is heavily debated, but may be influenced by habitat decline, invasive species and climate change.

 Habitat loss is a primary contributing factor for the decline in pollinators. Many insects are habitat specific, and cannot strive in other environments (New York Bee Sanctuary, 2015). With the construction of roadways, farms, housing developments and cities, insect pollinators are pushed away and begin to die out. These massive concrete jungles remove any prior places for them to feed, nest and diapause during winter. Habitat decline is not limited to habitat loss though. It also includes habitat degradation. Degradation is the decline in quality in a habitat. This could be from over use of resources, pollution, or various other factors. In fact, nearly all factors to pollinator decline contribute to habitat quality. A 2002 published study recorded the population status of Diptera psychodidae (drain flies) in Columbia. The study consisted of two locations. One was severely degraded, while the other was more so untouched. The degraded habitat represented was San Andres Sotavento, and the intact habitat represented was a reserve in Coloso. The study lasted eight months, and used various forms of traps to collect the flies. The study resulted in the capture of 18,312 flies. The intact environment yielded 15,988 flies, while the degraded environment only produced 2,324 flies (Travi, Adler, Lozano, & Caden, 2002). Catastrophes like this are not limited to Columbia. They are happening all over the world. Many haven’t been given proper media attention or simply haven’t been discovered yet. We cannot deconstruct our cities, but we can establish more reserves where construction may not take place. This would limit the amount of future habitat loss.

 Invasive species are another primary contributing factor to the decline of pollinators. One of the most infamous invasive species in the United States, is the Red Imported Fire Ant. Fire ants were introduced to the US during the 1930’s by accident from South America. Since then, they have rapidly spread throughout the Southeastern and Southwestern regions. A 2017 map from the US Department of Agriculture shows that the fire ant invasion has spread to all Southern states and reached as far as Midwest Oregon on the Western sea border (United States Department of Agriculture , 2017). Fire ants are extremely tolerant of environments and reproduce quickly. A single queen colony may build up to 150 mounds and reach as many as 7 million ants per acre (Amdro, n.d.).  Fire ants cause both direct and indirect stresses on native pollinators. Direct stresses include predation. These mostly include non-flying pollinators, or flying pollinators whilst they are still in larva stage. Because fire ants are omnivorous, they consume plant material as well. Fire ants often cut into the stalks of grain plants, and eat other devolving plants fruits and seeds (Extension, 2019). This is an indirect stress on pollinators. Although most grains do not need insects to pollinate, they do provide pollen to insects regardless. Eating the plants that pollinators rely on results in dwindling flowering plant populations. Pollinators struggle to find the remaining flowering plants, as crops and natural plants are devastated. Fire ants are not the only invasive species in vast numbers. The beloved European Honey Bee is actually an invasive species. Honey Bees were introduced to the Americas by European settlers soon after the establishment of Jamestown (Garvey, 2014). Since then they have been spread by man throughout the Americas. Honey bees are generally not considered invasive, as they pollinate extensively for us. But, they were not the first bees here. The problem with Honey bees, is that they apply stress to the native bee species. Taking resources and slowly driving native species out of their natural habitat. An example of this is the Michigan blueberry farm bees in paragraph one. Honey bees have also been attributed to the spread of disease amongst native populations. One disease that has resulted in the decline of native bees is Nosema bombi; a fungal disease with strands similar to that of diseases affecting Honey bees (Rogers, 2017). Currently there is not much that can be done about these invaders. Fire ants often require harmful chemicals to the environment to kill them. Honey bees are considered too valuable to our agriculture.

 The final primary contributor to the decline of pollinators is climate change. Because many pollinators can only withstand specific temperatures, they are at risk of species loss due to change in climate. Global temperature is projected to increase between 2 º -  4º Celsius by 2050. This heavily depends on the status of emissions leading up to this date. During a study in Brazil, scientist determined that pollinator loss could be around 13% by 2050. If their hypothesis is correct, 90% of species would suffer some form of species loss. Not only would pollinator populations be impacted, but crop yields would decline as well. This is a direct result of the decline in pollinators in the area. (Giannini TC, 2017). Climate change is a global phenomenon. Crisis like that in Brazil will happen all over the globe if temperatures continue to rise. With so many agricultural crops depending on pollinators, decline in them will devastate the agricultural economy. Increasing temperatures could threaten the existence of Honey bees. It is estimated that the disappearance of Honey bees could result in the consumer surplus loss of between $210 million and $430 million dollars (Dharam, 2011). In order to stop the increase of global temperatures, we must reduce the amount of carbon emissions entering the atmosphere dramatically. Implementation of more efficient power sources such as solar, hydropower, nuclear and wind energy would decrease emissions.

 Pollinators are extremely important to us. However, because of habitat loss, invasive species and climate change, the presence could begin to dwindle. It is critical that we implement new ideas and strategies to combat these factors. Unchecked habitat loss will eliminate the possibility species returning. Even if the climate is controlled more efficiently, many of the species that are already displaced will continue to struggle in their new environments. Invasive species that are not dealt with will continue to put stress on native species that have no way to combat and compete with them. On top of both of these factors, climate change will reduce populations on pollinator species as well. Because most native species cannot tolerate other temperatures than that of their natural habitat, they will cease to exist, at least in any substantial numbers. In conclusion, we need to draw our focus to the pollinator and do what we can to fix this global crisis.

Bibliography

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• Dharam, A. P. (2011, 9 28). Climate Change and Pollinators. Pollination Biology, 479 - 508. Retrieved from https://link.springer.com/chapter/10.1007/978-94-007-1942-2_15
• Extension. (2019). What do fire ants eat? . Retrieved from Extension: https://ant-pests.extension.org/what-do-fire-ants-eat/
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• Giannini TC, C. W.-F. (2017, 8 9). Projected climate change threatens pollinators and crop production in Brazil. Retrieved from PLOS ONE: https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0182274
• Isaacs, R., & Kirk, A. K. (2010). Pollination services provided to small and large highbush blueberry fields by wild and managed bees. Journal of Applied Ecology, 841.
• New York Bee Sanctuary. (2015). Let's Reverse HABITAT LOSS. Retrieved from New York Bee Sanctuary: http://www.newyorkbeesanctuary.org/habitat-loss
• Rogers, N. (2017, 1 23). How the Bees You Know are Killing the Bees You Don’t. Retrieved from Inside Science: https://www.insidescience.org/news/how-bees-you-know-are-killing-bees-you-don’t
• Sasaki, M., & Hoshiba, H. (2008, 11). Perspectives of multi-modal contribution of honeybee resources to our life. Entomological Research, 38.
• Travi, B. L., Adler, G. H., Lozano, M., & Caden, H. (2002, 5 1). Impact of Habitat Degradation on Phlebotominae (Diptera: Psychodidae) of Tropical Dry Forests in Northern Colombia. Journal of Medical Entomology, 39(3), 451-456.
• United States Department of Agriculture . (2017). Potential United States Range Expansion of the Invasive Fire Ant . Retrieved from Agricultural Research Service: https://www.ars.usda.gov/southeast-area/gainesville-fl/center-for-medical-agricultural-and-veterinary-entomology/imported-fire-ant-and-household-insects-research/docs/potential-united-states-range-expansion-of-the-invasive-fire-ant/