The Effect of Imidacloprid Pesticide Combined With Oxalic Acid Mite Treatment on
Apis Mellifera Mortality Wadley1
The Effect of imidacloprid combined with oxalic acid mite treatment on Apis mellifera mortality
Courtney Wadley
Abstract:
This study is a comprehensive collection of information on global bee colony decline and the factors that contribute to it. Imidacloprid and oxalic acid have each individually been known to contribute to Apis mellifera mortality and bee colony decline. While these factors have been studied individually, little to no research has been conducted on how the combinations of these and other factors affect mortality rates of Apis mellifera. Results suggested that the combination of feeding Western honey bees imidacloprid and treating them with oxalic acid leads to extremely significant and high mortality rates compared to other individual treatment groups.
Research Question
How does exposure to Varroa mite treatment and plant pesticide affect Apis mellifera mortality?
Background Research
Introduction:
Agricultural Research in the United States has revealed that the global population of bees (domestic and wild) is rapidly declining. This is troubling news, as bees serve as one of agriculture’s most important pollinators. Honey bees for many years have been successful in supporting human agriculture through pollination (Santos, et al., 2009). Some scientists believe that the phenomenon is occurring because bees are being exposed to sub-lethal amounts of pesticides, while others claim miticide (chemical treatment used to control pests in hives) indirectly affect bee mortality. Many factors such as bee diets, pathogens, parasites, diseases, global warming, and pesticide use were each thoughtto be the primary cause of this population calamity, but recent studies suggest that bees’ interaction with multiple factors may be the problem’s root (Pettis, et al., 2013).
Rapid decline in bee population negatively impacts the global economy. Because bees provide such an essential ecological service, humans depend on food produced as a result of pollination to make profit in the primary sector. There has been a six percent decline in vegetable availability, and with many crop yields producing similar patterns, profits are also on a major decline. Humans utilize many resources, including money, to harvest the pollinated crops. When there is too high a demand and not enough supply, global food prices increase, making synthetic and less healthy options objectively cheaper. This evidence proves the recent increase in bee mortality is not beneficial to the primary sector of the global market (Potts, et al., 2010).
The recent decline in bees can be attributed to many factors. But while the factors have been thought,in many cases, to be the cause of such a population and global crisis, these factors have never been considered together as cause for global bee colony decline. This is a pressing issue which needs to be studied with more intensity and focus on the relationships between factors as opposed to individual effects. The two most commonly individually studied factors seem to be the effect of plant pesticides on Apis mellifera and the effect of mite treatments on Apis mellifera (sources). This is why experimenting to see the effect of mite pesticides and plant pesticide treatments combined on bee mortality is so important to the future of global environment health.
Apis mellifera:
The subject of this experiment is the Apis mellifera (or Western honey bee). Western honey beeshave existed for millions of years serving as pollinators (Hester, 2015). Apis mellifera were brought to North America during the seventeenth century with the American colonists. This is why Western honey bees are also known as European honey bees (Sammataro and Avitabile, 1998). Western honey bees are classified as eusocial insects. Eusocial insects are organisms which cooperate in a cohesive pattern and collectively share attributes of one organism. Therefore, each colony functions as one cohesive organ system and performs tasks as a superorganism. Eusocial insects, such as bees, work specifically as nest-bound superorganisms, meaning the hive members depend on each other to maintain a hive’s (equilibrium) homeostasis. Honey bees cannot survive individually without the support of a hive or colony(Bonoan, et al, 2014).
Apis mellifera hives maintain homeostasis and functions as superorganisms through a caste system. The hive caste system dictates which occupants of the hives perform certain tasks. According to the Ontario Beekeeper’s Association, the queen, workers, and drones make up thethree hive castes. The queen and worker bees are all female while the drone bees are male. The queen bee decides whether a bee will be born a male drone or female worker through fertilization. Fertilized eggs are born female workers while unfertilized eggs are born as drones (2015).
The queen is at the top of the caste system function, and is essential to the survival of a colony or hive. A queen can be recognized as being slightly larger in size compared to the average worker bee which has short wings and a narrow abdomen. Queens live mainly to produce eggs, therefore creating more bees, for the entire hive.Queens have an average life span of two to four years and during that time laid an average of 365,000 to 547,500 eggs per year. The queen is vital to hive survival, and because of that, the workers keep a queen well fed and protected. Young worker attendants care for the queen, and constantly lick and groom her body; thereby, distributing pheromones which are essential to hive survival. Queen bees become fertile through a behavior known as the mating flights, in which the queen leaves the hive or colony as a virgin queen, shortly thereafter, inseminated with thousands of drone sperm. If promiscuous mating is not successful, the queen would only mate with a low number of drones, leaving the health of the hive at risk due to the lack of brood (bee pupae) genetic diversity (Hester, 2015).
Worker bees are second in the caste hive system and also vital to hive health, with their population making up the majority of a hive. Worker bees are infertile females and are a hive’s smallest bees. These bees serve primarily to keep the cohesive hive organ system running.A worker bee has several hive responsibilities which change during her life-span. During the first few days the newly hatched worker bee keeps cells clean and warms brood cells. The next few days she would proceed in the days after to feed older and then younger larvae. Next, she would transport food and repair damages to the hive. Some worker bees then go on to attend to the queen. Thepenultimate job for some workers is to become a guard bee, which is a bee that protects/surroundsthe queen and hive. The final job of a female worker bee is to forage for resources. The collection of resources is important for hive survival, and is essential to colony homeostasis (Hester, 2015).
Drones are at the bottom of the caste system. This type of bee possesses short legs, large compound eyes, and large flight muscles. They do not perform any tasks throughout the hive and nor do they feed themselves, because drones either barely or do not possess the physical characteristics required to forage in the environment. These bees only serve the purpose of fertilizing virgin queens during mating season. Drones mate by participating in the spring mating flight, in which bees will fly near a hive and try to fertilize a virgin queen during flight. After mating with a virgin queen, drones fall to the ground and die. These bees live towards the bottom of the hive and are usually kicked out of the hive by female worker bees or are dead by winter time each year (Hester, 2015).
During the winter time bees often face varying temperatures, which signals danger for the incoming brood and the health of the hive. It is important to note the natural maintenance practices of the hive. Broods in the hive need to maintain a steady temperature of 35-36o Celsius at all times for positive growth and development. To keep this temperature constant, the worker bees of the hive cluster around the brood cells and flex their thoraces (which are pressed against the pupae) rapidly (Bujok, 2002). Honey bees must constantly regulate temperature because their hive is immobile. This specific temperature range must be maintained because if temperatures are not favorable brood mortality and a hindrance in development can occur. Unfavorable temperatures can also lead to weak immune systems, causing increases in bee risk and susceptibility to pathogens, pesticides, and disease (Bonoan, et al., 2014).
Pesticides:
Many factors must come together in a hive so a colony can survive, but detrimental agricultural practices such as intensive pesticide use has proven to hinder hive homeostasis. In fact, scientists have pinpointed intensive pesticide use as the reason for such global bee population decline. Researchers Chakrabarti,Rana,Bandopadhyay,Naik,Sarkar, andBasur recently conducted a study investigating the effects of sub-lethal exposure to pesticide in an agricultural landscape on the olfaction and overall health of the Indian (Western) honey bee.The scientists asked the question, if native Apis ceranae are exposed to sub-lethal amounts (1.81 +.04) of pesticide for a significant amount of time, then how does this affect the bees’ olfactory system? The results found were that all honey bee samples produced similar results, there was a decrease in Proboscis Extension Reflex (PER) in High Intensity Crop (HIC) honey bees; there was a higher intensity of free (Calcium) Ca2+ in the brain of LIC (Low Intensity Crop) honey bees, and multiple pesticides impact bee olfaction capacity. The results were presented in a simple and easy to read format with an informative section which described how the results were found.The authors came to the conclusion that bees being exposed to sub-lethal amounts of pesticides in agricultural setting impairs the olfactory senses of bees, causing them to lose their way back to the hive. Bees cannot survive without the support of a colony just as a colony cannot function without workers (2015).
Research reveals the pesticides which mostaffects honey bees negatively are neonicotinoids. Neonicotinoids are commercial insecticides which are used to kill or remove unwanted pests from plants.Neonicotinoids were introduced into commercial agriculture production in the 1990’s, and are now the most used pesticides/insecticides in the world. These insecticides are utilized for agriculture in over one hundred and twenty different countries to control over one hundred and forty different pests such as moths, caterpillars and other insects harmful to crop health. Neonicotinoids are so widely used that they were valued at one point five billion dollars in the 2008 stock market. The pesticide works by remaining present in plant tissue, killing insects that consume the plants, but are thought to have no toxic effect on mammals. Numerous studies, including conclusions found in the study conducted by Chakrabarti, Rana, Bandopadhyay, Naik, Sarkar, and Basur,proves even sub-lethal exposure to these pesticides are toxic to the honey bee. Many countries and organizations such as the European Union have taken this information into account and have banned use of the three most controversial pesticides. These pesticides include Imidacloprid, Clothianidin, and Thiamethoxam (Lundin, et al., 2015).Honey bee risk is when Apis mellifera have higher chances of being killed or hurt, and hindering bee population growth and sustainability.Neonicotinoids can hinder cognition of honey bees, affecting how they forage and increasing Apis Mellifera mortality risk (Tan, et al., 2014).
One research study confirmed claims that pesticides can even increase chance of infection due to pathogens and parasites. In Crop Pollination Exposes Bees to Pesticides Which Alters Their Susceptibility to the Gut Pathogen Nosema ceranae, scientists tested the hypothesis that if Apis melifera experience consumption of honey bee diets, parasites, diseases and pesticides in an agricultural setting, then the interaction the bees have with parasites will have stronger negative effects on managed honey bee colonies. The background provided to support the hypothesis includes information on research concerning the sub-lethal effects of pesticides on bees, surveys on the different colony reserves and building material used, and background on Nosema (the investigated pathogen thought to impair olfactory senses within Apis mellifera).The results showed that all pollen collected contained pesticides, insecticides and fungicides. The amount of pesticides found was discovered to be similarly large across all hives. In addition to the pesticides present, researchers also found 147 out of all 630 bees were infected with Nosema.Nosema impairs the olfactory senses of honey bees and causes them to become lost on their way back to the hive from foraging. The researchers came to the conclusion that pesticides used by farmers have significant effects on a bee’s susceptibility to parasite and Nosema infection (Pettis, et. al, 2013).
Imidacloprid:
As stated previously, Imidacloprid has been banned from commercial use in certain countries and organization membership provinces. This is because Imidacloprid is a type of neonicotinoid pesticide. The metabolites of Imidacloprid aggravate nicotinic acetylcholine receptors and negatively impact the pollinating behavior of Apis mellifera. Use of Imidacloprid on crops statistically decreases pollination service quality by 6%-20%. This means that 6%-20% of crops do not get completely pollinated by the bees. This decrease in performance also negatively affects bees’ abilities to perform their duties such as enter the hive, forage, and even return to the hive. A bees’ ability to return to the hive is crucial for bee and hive survival (Tan, et al., 2014).
Imidacloprid is the most commonly used and researched pesticide (Lundin, et al., 2015).In one research study, Imidacloprid Alters Foraging and Decreases Bee Avoidance of Predators, Ken Tan and his fellow researchers hypothesize that if neonicotinoids (harmful insecticides) alter honey bee foraging behavior, then neonicotinoids would also impair a bee’s ability to sense danger and avoid predators.To support their hypothesis, Tan provided an extensive background on how Imidacloprid (a neonicotinoid) decreases foraging activity of bees and how neonicotinoids affect bee behavior around the world. Neonicotinoids have varying effects on Apis mellifera around the world depending on region and indigenous species. The results of this experiment showed there is a huge effect of pesticide concentration on the number of bees which returned to feeders after foraging, and that increasing pesticide concentration reduces the average amount of nectar collected, and that exposing bees to heavy concentrations of Imidacloprid causes bees to not avoid dangerous predators.After gathering all of the results, it was concluded that neonicotinoid pesticides impair honey bee cognitive responses and also concluded that significant concentrations of neonicotinoids can impair a bee’s ability to sense and avoid danger. Neonicotinoids are proving to be a key factor in global bee decline (Tan, et. al, 2014).
Miticide:
Another variable considered in the study is miticide. Miticide is man-made pest control used heavily around the 1980s and still used today to remove mites from bee hives. In 1984, Tracheal mites and Varroa mite infestations massively decreased United States bee population, prompting the invention of miticide. These chemicals served as anthropogenic (man-made) hive maintenance for years, and are supposed to not harm bees while killing off the mites. However,evidence has shown that it is difficult to create miticide completely safe for bees yet still be effective. Even with the advanced technology of miticide, Apis mellifera continue to die off in colonies at alarming rates (Burley, 2007).
Bee mortality has shown a rapid increase in recent years, and rates have increased in many regions of the world. Bee mortality rates are the average numbers of bee or colony deaths per year. The United States has lost fifty nine percent of its bees from 1947 to 2005 and meanwhile, Europe has lost twenty five percent of its colonies from 1985 to 2005. This troublesome news proves that mortality rates are rapidly increasing year by year. There are various consequences associated with this massive bee genocide: significant decrease in crop yield (amount of food produced), decrease in obtainable profit from crops, and drastic negative environmental impacts. When speaking specifically of harsh environmental impacts, a few effects concerning bees are very important to understand. Western honey bees are a primary agricultural pollinator. The crops they pollinate account for one third of all of the food humans consume. Without bees, there would be a significant increase in demand for pollinator intensive crops such as almonds, oil seed rape, watermelon, apples, broccoli, and many others. This decline causes a decrease not only in biodiversity but also food supply. Pollination is the major ecological service they contribute to human beings (Burley, 2007).