Thursday, January 30, 2014

Environment’s Role in Parasitic Relationships


There are many parasitic relationships in today’s environment. This is where a parasite will use an organism to its advantage by getting proper nutrition or living conditions of some sort from their chosen host. (1) There are many things that could influence how parasites choose their hosts and gain the proper abilities to do so. One of the major influences is the environment. Factors caused by the environment can greatly influence the strengths or weaknesses of a relationship between a parasite and its host. (2) Some of these environmental factors include, but are not limited to, the temperature and altering an organism’s habitat. (3) 


Environmental factors can greatly strengthen the relationship between a parasite and its host. For example, whenever temperature increases in the habitat of a host and parasite, hosts can obtain the ability to have a greater amount of offspring. This being said, warmer temperatures are expected to yield a stronger presence of parasitic relationships, because that will increas the amount of susceptible hosts for the parasites. (4) As well as this, there are some parasites that survive better in the warmer temperatures, thus making them a bit stronger. For the malaria parasite, Plasmodium falciparum, temperature plays one of the biggest roles in its development. As well as the proper amount of rainfall, warm climates are crucial in order for the mosquitoes, the intermediate host of P. falciparum, to survive. This being said, mosquitoes are less likely to bite in colder temperatures, thus inhibiting the spread P. falciparum. (5)

Mosquitoes less likely to bite in cold temperatures (6)


Not only can the environment have a positive influence on the relationship between the host and the parasite, but also it could affect it negatively and create a disturbance or stress for the organisms. (3) For example, humans can alter organisms’ habitat by converting a forest to something like an amusement park. This changes the environment completely for the organisms that once occupied that space, and thus creates a stressor among them. This causes the relationship between any kind of host and parasite to weaken, which might ultimately lead to the parasite’s life coming to an end. In this instance, the parasite is more affected by the environmental disturbance than the host.  However, in other cases, different hosts in a single environment may start dying rapidly thus causing the parasites to eventually be removed from the population as well. (3) The malaria virus, P. falciparum, could also be used as an example to describe how the environment can influence a parasite negatively. Whereas warmer temperatures aid in strengthening the relationship between P. falciparum and its mosquito host, the colder temperatures weaken it. Another species with similar results is the Daphnia longispina and the Caullerya mesnili parasite. An experiment was conducted that resulted in more D. longispina species being infected with C. mesnili in 12°C rather than at 20°C. (7) This being said, warmer temperatures have an opposite affect on C. mesnili than how it affected the malaria parasite.

Daphnia longispina (8)


The environment can affect parasitic relationships in many different ways. For example, colder temperatures have a different affect on different types of organisms. This explains why some species can only survive in certain places around the world.  This also suggests that the environment has a lot to do with the selection of hosts among different parasites (9).  Environmental factors can also take a role in the explanation of why some parasitic relationships are not strong in areas that would be expected. This could occur in places where an organism’s habitat has been altered.



  1. I found your post very informative and you presented very good examples regarding how the environment can impact various parasites. I would also like to add the environment of some humans bodies can also fight off certain parasites. For example, humans with one allele for sickle cell disease have a better chance of fighting malaria, due to the their red blood cells not being able to hold hemoglobin properly . This makes it harder for the malaria parasite to survive in this environment.