Diesel Fuel Exhaust and Impact on Honeybee Population

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Honeybees worldwide are currently facing a new and dangerous threat to their sensitive population. According to researchers from the University of Southampton, diesel fumes and air pollution make it more difficult for honeybees to find flowers, reducing the amount of available food source for the hive. This reduction of available food is of significant concern because it directly impacts the future viability of the species. Absent reliable and quality food sources, the bees may not be able to survive.

The honeybee (scientific name, apis millifera) has become an important part of agriculture in the world. Originally native to Asia and the Middle East, the honeybee is now naturalized across the globe and can be found on every continent, absent Antarctica (Kozhukhov). Researchers found that honeybees have “one hundred and seventy odorant receptors,” which the honeybees use to locate, identify and recognize sources of food (University of Illinois at Urbana-Champaign). Worker honeybees rely on “olfactory clues,” and then fly from flower to flower in pursuit of these clues (University of Illinois at Urbana-Champaign; Kozhukov). Upon confirming a food source, the worker bee fills its honey sac with nectar and returns back to the hive to deposit the nectar (University of Illinois at Urbana-Champaign; Kozhukov). The worker bee then communicates the location of this food source back to the other worker bees through a complex, but highly standardized, the pattern of dance, so that the other honeybees may then go out and perform the same bee functions (Kozhukov). Throughout its travels, worker bees also provide the important function of cross-pollinating crops for farmers, by transferring pollen from stamen to the pistil structure (Rucker et al. 956). In fact, honey bees function as the primary source of pollination for crops produced in the United States, as well as in other countries (Kozhukhov). These crops include apricots, pears and a watermelon (Kozhukhov). Honeybees also produce the seeds of many vegetables, including asparagus, carrots and turnips (Kozhukhov). A reported seventy percent of the world’s agriculture relies directly on pollination from honeybees, translating into thirty-five percent of the world’s food production (Girling et al. 1). One estimate places the value of this honeybee activity at over $135 billion worldwide (“Bees’ ability”). Without honeybees, the agricultural industry would have to perform this pollination function on its own, using other most costly and more cumbersome methods to complete the task (“Kozhukov”). This would create significant financial hardship for an already challenged agricultural industry.

However, in recent years the valuable honeybee has faced a continuing struggle to survive. Honeybees are generally susceptible to the virus, bacterial disease and parasites, resulting in a diminished number of bees, worldwide (Kozhukhov). Nosema is a virus that reportedly causes dysentery and paralysis in adult bees, and is responsible for a natural decline in the honeybee population (Kozhukhov). Additionally, the Honey Bee Tracheal mite, as well as the Varroa mite, has reportedly killed tens of thousands of honeybee colonies in North America alone (Kozhukhov). These mites also decimated the bee nationwide population during the 1980s, creating a significant issue for farmers (Rucker et al. 956). Unfortunately, in their ongoing efforts to control the mites and prevent a repeat of the tragedy, some farmers inadvertently poison the honeybees with the same pesticides and fungicides that they use to treat them in the first place (Kozhukhov). This effectively diminishes the honeybee population to even lower levels (Rucker 956). Honeybee colonies are also frequently threatened by natural animal prey. As a favorite food of cane toads and birds, the animals catch and then eat honeybees on their way back into the hive (Kozhukhov). Robber flies also eat the bees as they fly from flower to flower in search of nectar (Kozhukhov). Other insects, such as hornets and wasps, actually invade the honeybee hives and then eat the young larvae (Kozhukhov). This not only damages the existing hive but impacts the future viability of both the hive and the bee population as well (Kozhukhov). Lastly, bears often destroy beehives in search of honey and larvae to eat, as this is a primary source of food for the species (Kozhukhov). Unfortunately for farmers, these are not the only threats to the honeybee population.

Air pollution (particularly in the form of diesel fumes emitted by motor vehicles) reportedly poses a significant threat to honey bees and their delicate sense of smell. According to research, diesel fumes make certain emissions into the environment, including radicals such as nitrogen dioxide, nitric oxide, carbon monoxide and sulfur dioxide (Girling et al. 1). Based on related research findings, these emissions interrupt “plant-to-plant” odor communication (Girling et al. 1). However, researchers in the United Kingdom chose to investigate whether diesel exhaust pollution had an impact on honeybees by interrupting the olfactory function in bees so integral to their basic functions (Girling et al. 1-5). The results of this study were significant for the scientific community.

Scientists found that diesel emissions are, in fact, extremely damaging to honey bees. In conducting their research, the scientists created a blend of eight floral chemicals and subsequently exposed them to diesel fumes (Girling et al. 1). These fumes included nitric oxide, nitrogen dioxide and carbon monoxide (sulfur dioxide was excluded from the study) (Girling et al. 1). Subsequent analysis of the odor spectrum of these chemicals found that after only one minute of exposure to the diesel fumes, two of the eight floral chemicals were completely unrecognizable (Girling et al. 2). As the exposure continued, two additional chemicals were further diluted by the diesel fumes (Girling et al. 2). After an additional sixty minutes of exposure to diesel fumes, the levels of p-cymene notably increased, further changing the chemical composition of the floral blend (Girling et al. 2). This resulted in significant changes to the odor produced, making it completely unrecognizable to the insects (Girling et al. 2). The honeybees were only able to accurately recognize the food source a disappointing thirty percent of the time (Girling et al. 3). To confirm these findings, the researchers similarly exposed the same floral blends to ambient air (free from diesel exhaust) (Girling et al. 2). This portion of the study found that the unpolluted air had no effect on the chemical composition of the scent, and bees were able to accurately identify these odors ninety-eight percent of the time (Girling et al. 2). This translates into a conclusion that in nature, free from air pollution, flowers emit a constant and identifiable scent. What is most important to note is that in order for a honey bee to recognize a food source, their basic function requires that they are first able to detect (smell) it (Girling 2). Given these findings, bees would no longer be able to recognize the floral odors once they have mixed with diesel fumes.

Some researchers posit that this inability to recognize flowers by smell may have significant negative effects on the honeybee colonies. While previous studies blame other factors (such as natural predators or pesticides) for the decline in the honey bee population, other argue that air pollution may actually be responsible for the decline in the bee population, because it renders the bees unable to locate quality food sources (“Bees’ ability”). Other researchers argue that the exhaust fumes could also significantly damage the honeybees’ nervous systems, permanently weakening their sense of smell to recognize even unaltered odors (“Bees’ ability’). It is clear that action must be taken in order to preserve the worldwide honeybee population and protect them from further exposure to diesel fumes - perhaps creating biodiesel from waste alternatives.

Countries like the United Kingdom have investigated the feasibility of implementing a comprehensive National Bee Action Plan. The United Kingdom is reportedly home to over 250 species of bees, including the honeybee (“Reviving Bees” 1). This country acknowledges the importance of these bees to both the food supply, and the economy (“Reviving Bees” 1). Concerned about the continuing decline in existing bee populations, advocates in the U.K. recommend the implementation of this national plan to save the bees (“Reviving Bees” 1). Included in the National Bee Action Plan are restorative measures, such as increasing the size of “Ecological Focus Areas” for the bees to forage and providing additional flowers and nesting sites for them (“Reviving Bees” 2). However, while the program addresses other key areas requiring action (such as limiting the use of pesticides, expanding prevention programs and improving protection site planning), the National Bee Action Plan does little to address the key issue of air pollution and the negative impact that it has on the honey bees. In fact, one producer of diesel fuel emissions would be the diesel fuel engines that operate tractors (and other farm machinery) working the fields. This apparent void in the reform needs to be corrected if the honeybee population is to be preserved.

The worldwide honeybee populations continue to decline at an alarming rate. This is due to a variety of factors, including what may be the most important – contamination from diesel fuel exhaust. Given the impact on the honeybees, it is imperative that diesel fumes are controlled so that the honeybees may continue to perform the important function of cross-pollination of crops, worldwide.

Works Cited

“Bees' ability to sniff out pollen badly damaged by traffic fumes.” Times [London, England] 4 Oct. 2013: 21. Academic OneFile. Web. 9 Dec. 2013.

Girling, Robbie, Inka Lusebrink, Emily Farthing, Tracy Newman, and Guy Poppy. “Diesel exhaust rapidly degrades floral odours used by honeybees.” Scientific Reports 3.2779 (2013): 1-5. Print.

Kozhukhov, Oleg. “Honey Bee.” Everything About. Encarta, 2 Jan. 2001. Web. 9 Dec. 2013. <http://www.everythingabout.net/articles/biology/animals/arthropods/insects/bees/honey_bee/>.

“Reviving British Bees: why we need a National Bee Action Plan.” Friends of the Earth. Friends of the Earth, n.d. Web. 1 Apr. 2002. <http://www.foe.co.uk/sites/default/files/downloads/bees_report_briefing.pdf>.

Rucker, Randal, Walter N. Thurman, and Michael Burgett. “Honey Bee Pollination Markets and the Internalization of Reciprocal Benefits.” American Journal of Agricultural Economics 94.4 (2012): 956-977. Print.

University of Illinois at Urbana-Champaign. “Honey Bee Chemoreceptors Found For Smell And Taste.” ScienceDaily, 27 Oct. 2006. Web. 9 Dec. 2013.