Honey Bee Parasites and Diseases Term Paper Sample

Parasites of the Honey Bee

The current term paper provides the description of three different groups of parasites, which affect the honey bees. They are Apocephalus borealis, Varroa jacobsoni, and Acarapis woodi. Two hypotheses were tested in this work. The null hypothesis assumes that these parasites have similar influence on the behavior and life of honey bees, whereas the alternative hypothesis states that their effects differ greatly. The description of the history of the parasites’ investigation, their hosts and mechanism of parasitism, economic importance, control, and preventive methods were studied for testing of the above mentioned hypotheses. The analysis of the information concerning Apocephalus borealis, Varroa jacobsoni, and Acarapis woodi revealed that these three groups of parasites have different effects on honey bees and their behavior. It is reflected in the location of the parasites and their influence on the insect’s body, its behavior and ability to collect pollen and make honey. Consequently, the null hypothesis was not proved.

Introduction

The current term paper covers several questions, concerning honey bees and their health issues, caused by parasites. It studies different parasites’ effects on the insects and their population and describes all the stages of their life cycle. Much attention is devoted to the behavior of honey bees and their ability to pollinate plants and make honey, when they suffer from different parasites. The investigation, performed in the current work, represents relevant scientific issues, which can be addressed only by application of scientific approaches to studying insects and parasites. The discussed issue represents an open-ended problem, which has numerous solutions, described below. Its relevance is based on the fact that parasites have a significant negative impact on the health and life of honey bees as well as their ability to pollute plants and make honey, which can lead to death of thousands of bees, reduction of pollen, decreasing plant diversity, lowering of the quantity of produced honey, and enormous economic losses.

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Hypotheses

Two hypotheses are applied for understanding the mechanisms of the influence of such parasites as Apocephalus borealis, Varroa jacobsoni, and Acarapis woodi on honey bees. The null hypothesis states that these parasites have similar effects on honey bees and do not influence insects’ daily hive activities and pollination of crops. The alternative hypothesis insists that these types of parasites have different effects on honey bees and their daily hive activities as well as on the pollination of crops.

Definition of Parasitism

The testing of these two hypotheses is closely connected with the parasitism in honey bees. Parasitism can be considered as non-mutual relationships between several species. In these symbolic relationships one species (parasite) benefits from the other (host). The first can be rather small and is not be observed by a human eye. There are different types of influence of the parasites on their hosts. Parasitoids, for example, usually kill their hosts during their life cycle. Those parasites that live outside the insect are known as ectoparasites. The parasites, which live inside, are entitled as endoparasites. They can exist in the body of the host or in the cells.

Brief Description of Honey Bees

As it was mentioned above, the major emphasis of the current work will be made particularly on honey bees. Their colors are light brown or golden-yellow with dark-to-white stripes (Orkin, 2016). Their legs are brown. Honey bees are usually about 15 mm long (Orkin, 2016). The body is oval and divided into several segments: antenna, stinger, legs, six segments of abdomen, and three segments of thorax (Orkin, 2016). On the bees’ head one can see the eyes (compound and simple), a part of the digestive system, and an antenna. The thorax contains legs, wings, and muscles (Orkin, 2016). The abdomen contains reproductive organs (in the queen and drones) or a string (in the queen and workers) (Orkin, 2016).

The colony contains only one queen, which copulates with drones and lay eggs into the cells (Orkin, 2016). The only purpose of the drones is mating with the queen. The workers are responsible for tending larvae in the cells and for feeding them. They are foraging for food all their life (Orkin, 2016). The collective behavior of honey bees is also connected with their aggressiveness, making honey, plant pollination, and special relationships with people. They still reflect some aggressiveness. For example, a queen may string other queens during the mating fighting (Orkin, 2016). Drones may be ejected from their nests during the low temperatures (Orkin, 2016).

The process of making honey is performed by gathering pollen from a flower, transferring it to honey-making bees, and passing it from mouth to mouth untill the significant reduction of moisture is achieved. During the collection of pollen, bees transfer the pollen grains from one plant to another. In such a way they participate in the pollination of plants (Dukas, 2005). The pollinated plants and produced honey are consumed by humans, who can keep honey bees in hives. They pay much attention to choosing a safe plant, for example, the one, which has no crab spiders (Dukas & Morse, 2003). Thus, a risk to encounter a predator may also alter the behavior of honey bees (Jones & Dornhaus, 2011). The insects can become aggressive and defensive, when they feel that there is a threat to their nests, stored food, and brood (Breed, Robinson & Page, 1990).

Bees’ behavior significantly changes when they are affected by parasites. As it will be described below, they can act like zombies, fly on the light at night, and at the same time interrupt the performance of their daily activities because of the changes in morphology. These changes can easily pass from one zooid to another through skin or laid eggs. The parasites can cause rather high mortality rates, which will be discussed below.
Honey bees try to deal with parasites by changing the location of their hives on trees (Seeley, Seeley and Akratanakul, 1982), and altering the interiors of these hives. They may express aggression towards other bees, which are infected, or increase the swarm in order to reduce the density of parasites (Royce, Rossignol, Burgett, & Stringer, 1991).

Comparison / Contrast

Apocehalus Borealis

Discovery

A professor of biology John Hafernik was first, who discovered the significant negative impact of this parasite on honey bees in 2008 in California (Reuber, 2015). He observed a bizarre and erratic behavior of bees, which were infected by Apocehalus borealis. The researcher discovered it in the test tube and suggested that he observed the CCD (Reuber, 2015). Since that time, it is estimated that Apocehalus borealis may act as the cause of CCD (Reuber, 2015).

Hosts

Bumble bees are attacked by this parasite mainly during their interaction with plants (Gillespie and Adler, 2013). It is notable that these parasites spread equally between two species of bumble bees (Bombis vosnesenckii and Bombus melanopygus). A special research, performed in California’s Central Valley and South Dakota, shows that 77 % of both species’ samples suffer from the discussed parasite (Core et al., 2012). Apocehalus borealis can be also widely found in the populations of paper wasps, which live on the territory of the USA (Core et al., 2012). The discussed parasite also has a heavy influence on the European honey bees, also known as Apis mellifera, especially after a close contact with the invasive African honey bee (Torto, Boucias, Arbogast, Tumlinson, & Teal, 2007).

Mechanism of parasitism

At the current moment there has been revealed various mechanisms of parasites’ spreading, such as laying eggs into the victim or attacking it in its larva, pupa, and imago states (Packard, 1868). Usually female bees, infected by Apocehalus borealis, use their position of an ovipositor with a string for laying eggs into the abdomen of honey bees. Most part of the larval stage takes place inside the host bee (Packard, 1868). A mature parasite is developed from the host’s head and thorax. The final stage of the development is ended with leaving the dead host. The development of larvae is associated with attacking bees’ brains. It causes their disorientation, because the process involves taking food from bees’ brains and muscles. It takes about a week, while the entire lifecycle lasts for about 28 days.

The likelihood of transmission of this parasite is rather high. As it was noted above, about 77 % of the observed honey bees were infected with it (Core et al., 2012). Moreover, according to a similar investigation, the rate of infection of Bombis vosnesenckii reached 80 % (Core et al., 2012).The parasites decrease the average lifespan of insects by about 11 days (Otterstatter, Whidden, & Owen, 2002). The insects, which host parasites, die. The observers notified that zombie-like behavior of parasitized bees, their flights near the light at night, lack of activity during the daytime, and other disordered actions can also lead to a death.

Economic importance

The economic importance of the consideration of the problem of Apocehalus borealis is extremely high, as 77 % of bees, which produce honey, are infected by it (Casuso, Mortensen, & Ellis, 2014). These bees are major insect pollinators. The annual net profit from their activity in different locations all over the world is about $215 billion (Casuso et al., 2014). The development of this issue can significantly decrease these financial gains.

Control Methods

The researchers, who study the discussed issue in the National History Museum of Los Angeles and in San Francisco State University proposed the ZomBee Watch control method (Casuso et al., 2014). It is based on the identification, observation, documentation, and reporting about the appearance of the insects, affected by Apocehalus borealis, in bee populations of different locations.

Varroa Jacobsoni

Discovery

This species is named after Marcus Terentius Varro, who was a scholar and kept bees (Reuber, 2015). It was first noticed in Java in 1904 and was later observed in insects, which inhabited Asia (Reuber, 2015). In 1987 Varroa jacobsoni was discovered in the USA, in 1992. It was also found in the UK and in 2000 it was observed in New Zealand (Reuber, 2015). Currently, Varroa jacobsoni can be found on all continents (Reuber, 2015).

Hosts

Varroa jacobsoni is feeding on the hemolymph of adult and even immature honey bees (Ellis & Nalen, 2016). Its native host is Apis cerana, which lives in Asia (mainly in the eastern region) (Ellis & Nalen, 2016). It is estimated that this species tends to have some natural defense that protects the insect from the negative effect of the mite. Apis mellifera, which unlike Apis cerana was affected by Varroa jacobsoni much later (about 50-100 years), did not get such protection (Ellis & Nalen, 2016). An additional attention should be paid to the existence of the significant number of variations of the internal immunity to this parasite in different colonies of Apis mellifera (Evans & Pettis, 2005).

Mechanism of parasitism

The time period during which Varroa jacobsoni enters the brood cells is considered to be the initial phase. It usually lasts from 4.5 to 11 days. An adult female is feeding on the adult bees, particularly on their hemolymph. It is usually placed in the abdominal segments of insects. The second phase is known as reproductive. It starts when a mature mated female incepts the larval cell of the insect. This female hides the larva near the bottom of the cell for several days. Then, it defecates to the upper part of the wall and lays eggs. After the release, the mite starts eating hemolymph of the bee. Then the new eggs are laid on the wall of the cell. The emerging bee is released from the cell with a mite. This phase lasts from 6 to 7 days. The further feeding is performed through the intersegmental membrane.

The major reason why the spread of Varroa jacobsoni is rather high is the fact that it can easily switch the hosts and move across the continents. According to the European research control, it can transmit with the efficacy of 70 % among the honey bees (Commission of the European Communities, 1986).

Economic importance

Varroa jacobsoni has a significant economic importance as it imposes extreme damages on the colonies of honey bees. The infection of the potential workers weakens and destroys them, therefore, preventing from reproducing the insects. The additional emphasis should be made on the enormous spread of Varroa jacobsoni. It kills both domesticated and wild bees all over the world, which causes serious economic problems to the agricultural sector. It affects the homey production and leads to the decrease in plant species. The appearance of Varroa jacobsoni in a colony of bees leads to the changes in their behavior. The infection of females with Varroa jacobsoni requires faster identification and removal of the dead brood (Marcangelli, 2001). It should also be considered, because mites can serve as activators of such viruses (Sumpter & Martin, 2004) as Kashmir bee virus and deformed wing virus (Shen, Yang, Cox-Foster, & Cui, 2005).

Control Methods

Varroa jacobsoni can be measured by special sampling tools. They include sticky screens, sugar shakes, and ether roles (Harbo and Harris, 1999). The first one is represented by a carbon coated piece in a sticky substance. It enables to protect bees from Varroa jacobsoni through a mesh and at the same times serves as a barrier to bees, because it eliminates their touching of sticky substance. They can be located under the nests. This method gives the most accurate results. The spread of Varroa jacobsoni can be also prevented by using ether rolls. It involves collecting bees into glass jars and spraying them by ether (Harbo & Harris, 1999).

The shaking of a jar would affect the adherence of Varroa jacobsoni inside the walls, and would enable the parasite identification with a possibility of its quantifying. This method is less accurate than the previous one. The additional attention should be payed to the determination of Varroa jacobsoni with a help of sugar shake. Powdered sugar is placed into the jar with the bees. The insects are shaken and released. The amount of dissolved sugar enables to determine the number of Varroa jacobsoni (Harbo & Harris, 1999).

The resistance to Varroa jacobsoni may be performed by the systematic selection of honey bees, which are more resistant to mites. Specific characteristics of some species of bees (such as Russian honey bees) affect the reproductive systems of Varroa jacobsoni mites (Harbo & Harris, 1999). Thus, insects become more resistant to them.

C. Acarapis Woodi

History

The considerable contribution to the study of Acarapis woody was made by John Rennie, who was initially investigating the causes of Isle of Wight Disease, as he assumed that the bees’ symptoms were related to it (Baker, 2010). John Rennie observed their inability to fly, disjointed wings, decreasing number of bee colonies, and death. When the scientist reported about Acarapis woody for the first time, he named it Tarsonemus woody. The final name was given by his co-worker Bruce White in 1921 (Baker, 2010). In North America, it was discovered in 1980 (Wilson et al., 1990). Since that time, Acarapis woody spreads all over the world and it can be found in all locations, where honey bees live.

Hosts

Acarapis woody affects honey bees of different types, i.e. both drones and workers. A special investigation revealed that there is no significant difference between the mites’ preferences for them (Dawickem, Otis, Scott-Dupree, & Nasr, 1992). However, they are influenced by the migration behavior of the insect. At the same time Acarapis woody adult females are found in a greater extent in drones, which migrate from one location to another (Dawickem et al., 1992).

Mechanism of Parasitism

Acarapis woody parasitize in the breathing system of honey bees. Females of Acarapis woody are infecting young insects. The mite goes to tracheas of insects, which live only one or two days (Dawickem et al., 1992). After 3-4 days, these female mites lay the eggs there. The number of eggs usually varies from 5 to 7. The further development depends greatly on the gender of an insect. Male mature parasites are usually formulated on the 11th – 12th day (Dawickem et al., 1992). They are from 125 to 136 microns in length and from 60 to 77 microns in width (Dawickem et al., 1992). The final stage of the development of adult Acarapis woody females usually ends on the 14th – 15th day (Dawickem et al., 1992). They are 140 – 175 microns in length and in 75 – 84 microns in width (Dawickem et al., 1992). The additional attention should be paid to the fact that the females may move alongside the body hairs of the insect and even move to another bee.

The likelihood of transmission is relatively low, because Acarapis woody mainly lives in the insects’ trachea, except for the periods, when females leave them for the contamination of other insects. They are highly affected by temperature, humidity, and other external factors. Thus, their chances for survival are low. They can be spread inside the colony because of the direct contact between the insects. A transfer to other colonies and regions is usually associated with the purchasing of bees and queens, or migrating insects.
The mortality rate of bees from Acarapis woody usually varies from medium to high. The infection becomes apparent at its heavy stages.

Economic Importance

The economic importance of Acarapis woody is significantly lower than the economic importance of Apocephalus borealis and Varroa jacobsoni. This statement is based on the fact that it does not directly causes the death of bees. However, it may shorten its life by a few days. Moreover, Acarapis woody has a negative impact on the life of bees. Their capability to collect pollen and make honey is reduced because Acarapis woody causes the disjoining of wings.

Control Methods

Nowadays, various control methods are applied to address Acarapis woody. One of the most wide-known and effective ways is the use of acaricides. Using of both natural menthol crystals and synthetic menthol pellets did not provide a significant reduction in the mite prevalence (Scott-Dupree & Otis, 1992). During the time periods of cool temperatures, the efficiency of this method is lowered, because an insufficient amount of vapor is released. At the same time, this vapor can repel insects from their hive during the days with high temperatures (Scott-Dupree & Otis, 1992). The control of Acarapis woody is also performed by Acarol.

Evidence of the Null Hypothesis Failure

The description of all three types of parasites (Apocephalus borealis, Varroa jacobsoni, and Acarapis woodi) and their impact on honey bee’s life and behavior debunks the null hypothesis and proves the alternative one. This statement is based on the fact that their impact on bees, crops, and agricultural sphere, connected with honey manufacturing and pollinating, differs greatly. All three parasites have different effect on the insect’s life and actions. While Apocephalus borealis leads to the insects’ death and changes their behavior, which can endanger their lives, Varroa jacobsoni weakens the out-reproducing hosts of colonies, and Acarapis woodi has a relatively mild effect on the honey bees’ life, as it just shortens it by several days and reduces the ability to collect pole and make honey. Apocephalus borealis develops inside the body and affects the muscles and brains, Varroa jacobsoni mainly affects cells and larva, and Acarapis woodi is living in tracheas.

Thus, the second and the third type of parasites cause significantly less damage to the honey bees’ morphology, than the first one. Apocephalus borealis and Varroa jacobsoni lead to relatively high rates of mortality, whereas Acarapis woodi does not lead to the death of insects. Due to the fact that all types of the parasites have negative influence on the behavior of insects and lower (or sometimes even eliminate) their ability to collect pollen, they cause direct economic damage. Decreased pollination can lead to the reduction of the diversity of plants and their quantity. It is also directly connected with the lowered production of honey, because honey bees, which do not collect pollen, have no any ability to produce it. The additional emphasis should be made on the fact that these negative economic tendencies can be observed all over the world, i.e. in all locations where honey bees live, as the above mentioned parasites can be found on all continents.

Thus, the significance of the discussed issue is rather high. However, it is recommended to perform more accurate calculations and researches on the economic impact of these parasites in different locations for a more precise understanding of the danger of the discussed crisis. Additional attention should be paid to the fact that no controversies were found in the analyzed sources.

Benefits of the Parasitic Relationships

Notwithstanding the fact that the above mentioned parasites cause enormous harm to the honey bee population, plant diversity, and economies, their existence can be rather beneficial. According to the Red Queen hypothesis, the interactions between species can be even more important than the environmental changes (Barnosky, 2001). Such interactions on the example of honey bees and their parasites were discussed in the current work. It assumes that this interaction stipulates a constant adaptation of living organisms for their further survival, instead of simple gaining a reproductive advantage.

Thus, notwithstanding the fact that the activity of Apocephalus borealis, Varroa jacobsoni, and Acarapis woodi causes the reduction of the number of honey bees, decreases the collection of pollen, and as a result negatively affects plants’ reproduction ability, lowers the production of honey and its availability to animals and people, who eat it (thus, forcing them to search for new types of food), it may have the significant benefit. The necessity to address the issue of parasites may require the development of protecting schemes and responses of bee’s organisms, and even breeding new species of honey bees.