Parasite-Induced Changes in Host Behaviour

Parasite-Induced Changes in Host Behaviour Parasite-Induced Changes in Host Behaviour: Is it Truly Parasitic Manipulation? Introduction Behavioural changes in the host when infected with a parasite were first observed in 1952, when van Dobben discovered that fish caught by cormorants (waterbird) were more likely to play intermediate host to the cestode, Ligula intestinalis than fish caught by fishermen (cited in Thomas et al., 2005). However it wasn’t until 1972 that the ability of parasites to manipulate their host’s behaviour in order to facilitate their transmission was discovered and demonstrated by Holmes and Bethel (cited in Poulin, 2000). They showed that infection of the parasite, Polymorphus paraoxus caused the amphipod, Gammaeras lacustris to display abnormal behaviours that led to an increase in its predation by ducks, the definitive host of the parasite. Since then there has been considerable research carried out in this area supporting the idea that parasites have adapted in order to manipulate their host, with a large number of parasites now known to cause changes to their hosts behaviour. There is a wide array of influenced behaviours from anti-predator behaviour e.g. mice infected with the tapeworm, Taenia crassiceots show no stress response to predation (Wheat, 2009); to reproductive behaviour e.g. female mice infected with the nematode, Trinchinella spiralis show inhibition of their sexual behaviours, limiting possible mate response (Kavaliers et al., 2000). In a few cases completely new behaviours in infected hosts have been observed, for example orb-weaving spiders infected by a parasitic wasp build unusual webs that are designed to protect the emerging larva once the host spider dies (Eberhard, 2010). More recently, the idea of parasitic manipulation has come under criticism, due to the lack of supporting evidence demonstrating that these behavioural changes provide parasites with a fitness benefit (a prerequisite of an adaptive trait), either in the form of increased transmission or survival (Poulin, 1998) and has therefore been suggested that the observed ch anges may just be an inevitable consequence of infection, or in some cases mediated by the host itself in order to counteract the negative fitness effects of parasitic infection. Understanding the origin of these behavioural changes is of great importance as there are many manipulative parasites that have implications for human health, such as malaria which alters the behaviour in the mosquito in order to increase transmission to humans (Lynch et al., 2014) and Toxoplasma gondii which can alter the personality of infected individuals (Worth et al., 2014). Manipulative parasites are also seen as playing as important a role as predation in shaping biological communities, even having an influence on non-host species (Hatcher et al., 2014). Adaptive vs. Non-adaptive Behavioural Change The argument that some of the previously observed behavioural changes of the host during parasitic infection are non-adaptive and just a consequence of infection generally refers to three different kinds of phenomena (Thomas et al., 2005). The first is the idea that the behavioural changes are just a side-effect of parasitic infection and confer no adaptive value for either the parasite or its host. However this is a questionable explanation as it is highly unlikely that any such change in behaviour will not provide a positive effect for either organism. Therefore this explanation should only be used if there is strong supporting evidence and not used as a default explanation, for example the parasitic cestode, Hymenolepis diminuta was shown to cause reduced fecundity in females of the beetle intermediate host, Tenebrio molitor and was seen as a side-effect, until further research discovered that the parasite produced a substance that inhibited vitellogenin uptake (Moore, 2012). Seco ndly some behavioural changes may be considered beneficial to the parasite, but are not due to manipulation by the parasite in order to do so, for example when the parasite Ligula intestinalis infects the Roach (Rutilus rutilus) a change in host migration to areas where predation by the parasites definitive host, ichtyopahgous predatory birds, are more common is observed (Loot et al., 2001). However it was found that these areas are more productive and it is therefore more likely that the increased energy demands caused by the parasitic infection had caused the Roach to migrate to these areas in order to negate this negative effect of the parasitic infection and increase its own fitness. Thirdly other adaptations by the parasite may have coincidentally caused behavioural changes in the host which unintentionally led to an increase in the transmission of the parasite to its definitive host, for example Fathead minnows (Pimephales promelas) are commonly infected by the trematode, Orni thodiplostomum ptychocheilus which caused a reduction in behaviours associated with host vision by the encystment of the parasite in the optic lobes, which leads to an increase in its predation by piscivorous birds. However this encystment in the eye may originally been favored by selection as it offers the parasite protection from the host’s immune system and not because it increased the transmission of the parasite to its definitive host (Shirakashi and Goater, 2005) On the other hand the argument for the adaptive nature of behavioural changes of the host during parasite infection is normally supported by the idea that it should show some degree of specificity in the intermediate host, for example P. laevis induces various behavioural and physiological changes in the crustacean amphipod, Gammarus pulex, such as altered drifting behaviour, altered anti-predator behaviour, partial castration and lower immune activity. These changes are not observed in Gammarus roeseli a closely related species, showing that the alterations by the parasite are specific to Gammarus pulex (Lagrue et al., 2007) Examinations on the effect of the acanthocephalan parasite, Moniliformis moniliformis on the behaviour of different species of cockroaches by Moore and Gotelli found that different behavioural changes had evolved for different species of cockroach supporting the adaptive nature of the host behavioural change (cited in Poulin, 1998). Indirect methods have also be en used to demonstrate the adaptive nature of altered behaviours in the host by determining whether the timing of observed behavioural changes coincide with the period when the parasite is infective to its next host. For example Tribolium confusum beetles infected with the nematode, Protospirura muricola only show observable changes in the behaviour of the beetles that make them more vulnerable to predation when the parasite has developed to the third larval stage. No behavioural change is observed in beetles home to the first and second larval stage. (Schutgens et al., 2013) Behaviour as a Form of Host Defense Not all changes in behaviour can be attributed to the manipulation of the host by the parasite as they do not benefit the parasite. The host is under selection to avoid parasites, and when possible to compensate for the negative effects of infection. Behaviour is often used in order to achieve this and is the first line of defence against parasites as it allows animals to avoid becoming infected in the first place (Moore, 2012). Animals may avoid infection by parasite propagules through behavioural means such as territoriality, site-specific defecation and mate selection. More drastic measures may be taken when trying to avoid ectoparasites, including migration, shifting habitats and lethal combat e.g. howler monkeys invest a significant proportion of their energy to slap at flies, and execute over 1500 slaps in a 12 hour resting period. Once a host becomes infected with a parasite, its behaviour will also be altered in order to minimise damage caused by the parasite. For example ani mals display sickness behaviours e.g. fever and behavioural chills, which may help in obtaining the benefit of increased care from other members of a group/population. Some animals, for example Chimpanzees, show self-medicating behaviour in which infected animals may consume medicinal plants that are not part of their usual diet. It is also possible in some cases that both parasite and host are shown to benefit from a change in host behaviour, in these cases it can be difficult to determine which organism is responsible for change, or whether it is a shared adaptation, for example caterpillars of several butterfly species play host to braconid wasp parasitoids and unlike non-parasitised individuals they perch at the top of high branches. It has been suggested this benefits the host by making itself more likely to eaten by a predator, killing both the parasitoid and host, but protecting its nearby relatives from the parasite. However it may also help the parasite by reducing the risk of hyperparasitism and therefore increasing its chance of survival. (Poulin, 1998). Conclusion Up to this point mainly laboratory based studies have been carried out in order to assess host behavioural changes due to parasite infection. Future research into the area needs to include field based studies in order to fully assess these changes in the natural environment. Currently very little is known about the molecular and genetic mechanisms underlying these changes. Therefore the basis as to how parasites cause these behavioural changes in there host is an area that needs to be addressed in order for these behavioural changes to ever be fully understood. Word Count: 1490 References Thomas, F., Adamo, S. and Moore, J. 2005. Parasitic manipulation: where are we and where should we go? Behavioural Processes, 68: 185-199 Poulin, R. 2000. Manipulation of host behaviour by parasites: a weakening paradigm? Proceedings of the Royal Society Biological Sciences, 267 (1445): 787-792 Wheat, S. E. B. 2009. Parasitic manipulation: The current state and future direction. University of Sheffield, Department of Animal and Plant Sciences Kavaliers, M., Colwell, D. D. and Choleris, E. 2000. Parasites and behaviour: An ethopharmacological perspective. Parasitology Today. 16 (11): 464-468 Eberhard, G. W. 2010. New types of behavioural manipulation of host spiders by a parasitoid wasp. Psyche: A Journal of Entomology. 2010: 1-4 Poulin, R. 1998. Evolution and phylogeny of behavioural manipulation of insect hosts by parasites. Parasitology. 116: S3-S11 Cator, L. J., Lynch, P. A., Thomas, M. B. and Read, A. F. 2014. Alterations in mosquito behaviour by malaria parasites: potential impact on force of infection. Malaria Journal. 13(164) Worth, A. R., Lymbery, A. J. and Thompson, R. C. A. 2013. Adaptive host manipulation by Toxoplasma gondii: fact or fiction? Trends in Parasitology. 29(4): 150-155 Hatcher, M. J., Dick, J. T. A. and Dunn, A. M. 2014. Parasites that change predator or prey behaviour can have keystone effects on community composition. Biology Letters. 10: 20130879 Moore, J. 2012. An overview of parasite-induced behavioural alterations – and some lessons from bats. The Journal of Experimental Biology. 216: 11-17 Loot, G., Brosse, S., Lek, S. and Guegan, J. F. 2001. Behaviour of roach (Rutilus rutilus L.) altered by Ligula intestinalis (Cestoda: Pseudophyllidea: a field demonstration. Freshwater Biology. 46: 1219-1227 Shirakashi, S. and Goater, C. P. 2005. Chronology of parasite-induced alteration of fish behaviour; effects of parasite maturation and host experience. Parasitology. 130: 177-183 Lagrue, C., Kaldonski, N., Perrot-Minnot, M. J., Motreuil, S. and Bollache, L. 2007. Modification of hosts’ behaviour by a parasite: field evidence for adaptive manipulation. Ecology. 88(11): 2839-2847 Schutgens, M., Cook, B., Gilbert, F. and Behnke, J. M. 2013. Behavioural changes in the flour beetle Tribolium confusum infected with the spirurid nematode Protospirura muricola. Journal of Helminthology. 1-12

motivation :: essays research papers

There are several Organizational Behaviors that can be attributed towards how successful a company or one in a company will be. I have decided that the two most important elements are the motivational behaviors and the stress factors. The reason I have chose these are that someone that is motivated and can deal with stress in positive ways will be a success. Also when a corporation can motivate its employees and helps them deal with stress they are usually successful as well. Stress is a very serious problem, and can be affiliated with many fatal conditions. Stress can also be put into positive use by the correct individuals. Eustress is stress at normal healthy levels and will be prevalent in motivated individuals. In emergencies eustress can be used to enhanced focus and give a burst of energy. Eustress also has other positive effects such as cardiovascular efficiency and increased arousal. In the Japanese workplace there is too much stress and is causing somewhat of an epidemic. Yearly about 30,000 workers die from a condition known as "karoshi†, which is when they literally work themselves to death. Although in America the stress levels haven’t become an epidemic some surveys show that about 75% of American workers consider their jobs stressful. There are several factors that contribute to these high stress levels. At the moment the way the world is becoming globalized and how America is in an economic recession that is causing downsizing are considered the two biggest stressors. The downsizing is not only because of the recession but a common trend in business is to hire less then adequate number of workers then working them to their full potential or even beyond their full potential. Another problem that causes a lot of stress is known as â€Å"a square peg in a round hole†. This is when an individual is in a position that does not fit their personality. An example of this is someone such as an extrovert working a position that is better suited for an introvert. Sometimes one personality may not fit what they are doing at work and will be more successful in a different position. This is something many managers ignore so if someone wants to change their job they have to do it themselves.

High School Student And Adulthood Essay

â€Å"The power which resides in him is new in nature, and none but he knows what that is which he can do, nor does he know until he has tried.† Understanding Defines Change Psychologists Scott Scheer, Stephen Gavazzi, and David Blumenkrantz undertook a comprehensive review and analysis of the psychoanalytic literature that discussed the rites of passage in adolescence; from the reading, they derived two truths concerning an adolescent’s rite of passages. Primarily, as Scheer, Gavazzi, and Blumenkrantz state, â€Å"Not all transitional events necessarily indicate the occurrence of life transitions† (1); however, â€Å"It is believed that both cognitive interpretation and integration are required before the event genuinely becomes a significant transition or rite of passage† (1). Essentially, to label a singular event as one that ignited a life transition, one must understand the resulting effects of the event. Additionally, according to Scheer, Gavazzi, and Blumenkrantz, the event that marks the end of the transitional period between adolescence and adulthood defines the rite. Principally, a singular event cannot accelerate one’s progression into adulthood without one realizing the effects or changes that the event caused. In â€Å"Self-Reliance† by Ralph Waldo Emerson, Emerson described the idealistic depiction of the Romantic hero’s rite of passage. Emerson states that â€Å"The power which resides in him is new in nature† (1), and he believes that a person should seek the meaning of that power for himself. Emerson’s statement that one doesn’t know the power that they have until one finds it (1) falls directly in line with Scheer, Gavazzi, and Blumenkrantz’s interpretation of one’s rite of passage. Scheer, Gavazzi, and Blumenkrantz postulate that one cannot arrive at adulthood without first understanding a transitional event. Similarly, Emerson reveals, in the quote at the top of the page, that one does not know his unique power until he has tried to find it himself. Likewise, if one didn’t find their unique power, based on the definition given by Emerson, one hasn’t successfully arrived at that â€Å"Time in a man’s education† (1), and, thus, has not successfully completed a rite of passage. Therefore, Emerson views rites of passage as events that are intrinsically bound to understanding, and without cognitive interpretation, an event cannot allow one to find one’s unique power, disqualifying it as a rite of passage. The idea that rites of passages are dependent upon cognitive understanding holds true throughout a number of literary texts. For instance, in Walden by Henry David Thoreau, Thoreau details the rite of passage of a king’s son. As Thoreau states, â€Å"One of his father’s ministers having discovered him, revealed to him that he was, and the misconception of his character was removed, and he knew himself to be a prince† (72). Like Scheer, Gavazzi, and Blumenkrantz’s postulated, the son’s discovery alone did not result in the personality transition from that of a forester’s child to a prince. Instead, the son had to realize that he was, in fact, a prince before the transition could completely take effect. Thus, for one to totally embark and complete a rite of passage or a life transition, one must understand the effects of a singular event. (487) Works Cited Emerson, Ralph Waldo. â€Å"Self Reliance.† Adventures in American Literature: Pegasus Edition. Ed. Bernard Brodsky. Orlando: Harcourt, 2004. 221. Print. Scheer, Scott, et al. â€Å"Rites of passage during adolescence.† Forum. n. page. Web. 17 Feb. 2013. . Thoreau, Henry David. Walden. New York: Penguin Classics Publishing, 2005

Anne McCaffrey essays

Anne McCaffrey essays Dragons. Creatures of legend, and also the title characters in many of Anne McCaffrey's books. . Anne McCaffrey is an excellent writer of Sci Fi/Fantasy books. McCaffrey has been writing full time since the late 60's and during her time as a writer she has amassed a great amount of fame. Though you may not know who she is, Anne McCaffrey is one of the most popular Science Fiction/Fantasy writers and her books are a must read. Anne McCaffrey was born on April 1, 1926 at 1:30 PM in Cambridge Massachusetts. Her parents are George Herbert McCaffrey and Anne Dorothy McElroy McCaffrey. She has two brothers: Hugh McCaffrey (deceased 1988), and Kevin Richard McCaffrey, still living. Anne was educated at Stuart Hall, Staunton Virginia, Montclair High School, Montclair, New Jersey, and she graduated cum laude from Radcliffe College, majoring in Slavonic Languages and Literature. Anne got married in 1950 and she had 3 children: Alec Anthony, born in 1952, Todd, born in 1956, and Georgeanne, born in 1959. Anne currently lives in a house of her own design called Dragonhold-Underhill-so called because she had to dig out part of a hill on her farm to build it. Her farm is located in Wicklow County, Ireland. Anne McCaffrey didn't hold very many jobs before becoming a writer. She was a character actress while in college and appeared in the first successful summer music circus in Lambertsville, New Jersey. After college she worked for Helena Rubinstein at Liberty Music Shop. She worked there for 5 years before she begun to write short stories for a living. Anne McCaffrey's interests are pretty varied. One of her biggest interests are horses. In fact, on her farm she has a private stable and she has horse trials at her farm. She also loves to ride horses. Her other big interest is dragons. She absolutely loves dragons. She also likes operas and operetta's. Anne McCaffrey has written a lot of books. Her ...

Sawing essays

Sawing essays This report is intended to give detailed information about Scotland; its Scotland was and still are inhabited by Scots, whom are descendants of Celtic peoples. A colony of Scots came from Ireland in the sixth century and united with the Picts, the original inhabitants, in the ninth century. Though some historians beleive that the first to live in Scotland were Iberians. They farmed, built ships, and made tools.The Iberians were one of the most ancient European peoples. Therefore, it is possible to say that Iberians were the first to inhabit Scotland. Later on, Celtic invaders entered England at about 600 B.C. and taught the Iberians new skills. The Scots fought against the Vikings in the north and England in the south, for a prolonged time. Feudalism began during the Norman conquest of England in 1066. This led Scots to flee and become refugees. They were given a substantial amount of land and were intoduced into the system of feudalism. At the time, King Malcom gave chartes out to towns and developed a similar parliament to England. Feudalism is a system in which the nobles of the Middle Ages kept ownership of their land. Feudalism controlled politics, financial affairs, government issues, and society. It had reached its height during the 1100's and the 1200's. Then, dramaticaly the system almost disappeared by the end of the 1400's. When Queen Margaret , King Malcom's wife, died in 1290; many Scots competed for the throne. Edward I of England declared one baron. He chose John Baliol as king of Scotland. ...

Role of Motivation in Second Language Acquisition Research Paper

Role of Motivation in Second Language Acquisition - Research Paper Example Through a questionnaire that sought to ascertain the level of their motivation and anxiety towards English acquisition as a second language, I was able to set up the base for a formal research to examine the level of motivational and anxiety patterns as a result, of second language learning. More significantly, the subjects of the research were Saudi student who was studying English for their general academic purposes and latter use in their careers expressed dissatisfaction in their early education. More so, the students indicated that both social and psychological problems caused them difficulty when studying English as a second language in their earlier education at primary, intermediate and secondary schools for a period of seven years. Literature Review In most cases, motivation as a way of enhancing second language learning is important for an individual to acquire successfully language competence. Therefore, this section of the research gives an overview of literature that is considered relevant in establishing my research objectives. More than often, it is hard to describe the motivation because of it complex phenomenon in different facets of life. Shuib & Al-Tamimi (2009) put more emphasis on the fact that, proper motivation remains relevant among learners of a second language as a way of enhancing their language competence. More significantly, both the social and individual decisions in the degree of effort and emphasis people make, as they set their goals in second language depends on the source of motivation.... More than often, it is hard to describe the motivation because of it complex phenomenon in different facets of life. Shuib & Al-Tamimi (2009) put more emphasis on the fact that, proper motivation remains relevant among learners of a second language as a way of enhancing their language competence. More significantly, both the social and individual decisions in the degree of effort and emphasis people make, as they set their goals in second language depends on the source of motivation. On the other hand, Ghazi et al. (2010) described the motivation as the voluntary forces that give an individual the will to develop direction, arousal, and persistence of goal-directed towards achievement of success in second language acquisition. In addition, they believe that motivation acts as a driving force that compels, energizes and prompts an individual to develop interest in a second language learning within a particular time in which focus is set on attaining a specified goal. Rubenfeld et al. (2007) describe the motivation as self-determination, which drives an individual’s motives towards their goal pursuits as inspired by either intrinsic or extrinsic aspirations. More so, the goals that drive an individual’s motive is aimed at attaining both the basic and psychological needs that later on leads to external approval and rewards (Dekker & Fischer, 2008). As a result, students undertaking English learning, as their second language in their studies derive their motivation from extrinsic goals. Even so, learners of second language could be driven by intrinsic goals as they intend to enhance their sense of belonging within the community that uses a second

Liquidity Risk Essay Example | Topics and Well Written Essays - 4000 words

Liquidity Risk - Essay Example On the other side, the market liquidity depends on the calculation of value risk and the length of holding period. So, the risk liability is attached with the issue of funding liquidity which may vary in the case of vast range of transaction (Fight, 421). The risk of liquidity tends to be managed, when market, credit and other risks are considered to be additional. There are several types of risk resolving techniques. These all are incorporated with the life of initial bank risk. The Federal Reserve System provided a banking risk framework designed by six factors. These include, reputational and liquidity risk, legal risks, market risks, credit risks. The structures of risk management are thus reviewed, making use of these risk categories. The supervision group is concerned with the liquidity risk fund, continue the preventive action against the other emerging risk and follow the current risk. All this preventive actions are fixed on revelation by majority of Federal Reserve banks. T his process tends to figure on a continuous basis, and as a result, measures to counter the existence of so many opportunities may result to risk (Morrison, 245). The financial risk is related with the possibilities of losing money of shareholder. On the other word, the investors did not have enough return on their investment in the company. This type of situation arises when the cash flow of the company proves inadequate to meet all the financial obligation of the company. At the time of insolvency, the creditors.