On pages 100-102
Dr. Moalem talks about an experiment done in Central America with a parasitic
wasp, Hymenoepimecis arargyraphaga. They manipulate and paralyze an orb-weaving
spider to take care of their babies. This relates to Big Idea #4, which states:
Biological systems interact, and these systems and their interactions possess
complex properties.
How are these
parasitic wasps able to paralyze and completely manipulate their hosts to
create a web when the larva is ready to cocoon? Explain why the manipulation of
the host is critical in the development and growth of the parasitic wasp. Using
outside sources and previous units, explain what effect parasitism has on the
population and food chain and also what different mechanisms hosts can use in
order to prevent their death.
Pranathi Merneedi (pmernee4@students.d125.org)
H. Arargyraphaga is a parasitic wasp that uses plesiometa argyra as a host for its young to grow. First, the wasp finds a plesiometa argyra and paralyzes it. Then, the wasp lays its eggs on the spider's abdomen where the egg will be protected. As a larvae, it'll feed on the spider's hemolymph, the circulatory liquid of insects. Once it's an adult, the wasp injects a chemical into the spider that tells it to construct a stronger web. This web will support the larvae's final transformation into adulthood. This is a true parasitic relation because in the end, the wasp makes it into the adulthood while the spider dies. This relates to Big Idea 4 and how Biological systems interact, and how these system's interactions possess complex properties.
ReplyDeleteThe chemical the wasp uses changes the spider's behavior and makes a sturdier web. One particular scientific study determined that the normal spider had 5 different step when making its normal web. However, the spider injected with the behavior modifying chemical constantly repeated the first 2 steps. Once finished, the spider waits to die while the wasp is about to hatch.
Parasites, in an ecological sense, can act as both predator and prey. For example, the wasp spider is a predator but ectoparasites in birds living on the Gulf of California act as parasites for lizards living on the coast. Parasites are involved in "78% of all links" in a California marsh food web and are an integral part of the ecosystem. They act as a check on certain species because parasite populations will grow in response to more food. To combat this, hosts can carry enzymes or use their immune system to battle parasites. For example, the human body has eosinophils to combat parasitic worms. Hosts and parasites share a unique relationship.
http://www.americanarachnology.org/JoA_free/JoA_v29_n3/arac_29_03_354.pdf
http://nerdychristie.wordpress.com/category/hymenoepimecis-argyraphaga/
http://www.nature.com/scitable/knowledge/library/ecological-consequences-of-parasitism-13255694
Andrew Arceo - ibanezrg120ftw@gmail.com
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ReplyDeleteHymenoepimecis arargyraphaga is a parasitic wasp from Central America. This parasite wasp grows in relationship with Plesiometa Argyra, an orb-waving spider native to Central America. For simplicity, Dr. Moalem refers to the spider as “Thane of Cawdor
ReplyDeleteand the wasp as “Lady Macbeth” seeing as both organisms only have Latin names. Lady Macbeth uses Thane of Cawdor as a host for its offspring. Lady Macbeth stings Thane of Cawdor and lays an egg on the spider’s abdomen as the spider is paralyzed. As the Thane of Cawdor wakes up and continues to spin its web, the egg slowly waits for the day until it hatches. The egg soon hatches into a larva, and this small parasite utilizes host manipulation in order to ensure its development. The parasite feeds off the blood of the spider until it injects the spider with a chemical. Still a mystery to scientists, this chemical somehow changes the behavior of the spider. According to Dr. Eberhard, “ The larva somehow biochemically manipulates the spider’s nervous system causing it to perform one small piece of a subroutine, which is normally only a part of orb construction, while repressing all the other routines” (Moalem 102). Rather than building its five step circular web, the spider starts to repeat steps one and two to build a special web for the larva’s cocoon. After a period of time, the spider becomes weak and the parasite kills and disposes of the spider. The parasite then spins a cocoon and lives on the reinforced webs until it emerges as an adult wasp. Hymenoepimecis arargyraphaga’s use of host manipulation by using chemicals to alter the behavior of Plesiometa Argyra relates to Big Idea 4: Biological systems interact, and these systems and their interactions possess complex properties.
Parasites have special relationships with their hosts. This host manipulation is a beneficial tool that is utilized by parasites to ensure its survival. In this case, Lady Macbeth injects a chemical signal into Thane of Cawdor in order for the spider to act in a way that is beneficial for the parasite. Thane Cawdor is able to spin a web that protects Lady Macbeth as it approaches its final stage of growth. This reinforced web ensures a safe environment and survival for the parasitic larva to grow. It is also important to note that through natural selection the parasitic wasp has evolved a trait (chemical signal) that stimulates the host to behave in a way that ensures the survival and reproduction of the wasp. In addition to Big Idea 4, this parasitic relationship also relates to Big Idea 1: The process of evolution drives the diversity and unity of life.
Parasites grow in relationship with its prey. Going back to the ecology unit, a parasitic relationship is one in which the parasite benefits and the host suffers. For example, a tick lives on a dog. The tick feeds off the blood and dead skin of the dog and the dog is greatly irritated. At the same time, these two organisms evolve together. The dog has developed a behavior to scratch away ticks. Similarly, the tick, in the case, does not completely drain and kill the dog. Without the dog population, the tick population would slowly die off until it evolved to find another food source. I also agree with Andrew’s statement above. Parasites can also act as a check on certain species as more parasites grow in response to more food. Looking back at the ecology unit, parasites can prevent a population from exceeding its carrying capacity.
DeleteTo fight against parasites and its parasitic relationship, hosts can prosper in symbiotic relationships with other organisms. For example, Fungus growing ants are harmed by parasites in garden environments such as Escovopsis. In order to combat this, these ants have evolved through symbiotic association with certain bacteria that inhibit Escovopsis. This, in turn, allows the ant to survive and reproduce. In agreement with the statement above, hosts also utilize their immune systems and different enzymes to fight off parasites.
http://necsi.edu/projects/evolution/co-evolution/parasites/co-evolution_parasite.html
http://rsbl.royalsocietypublishing.org/content/2/1/12.short
Weilly Tong (wtong4@students.d125.org)
On pages 100-102 Dr. Moalem describes the relationship between a parasitic wasp called Hymenoepimecis argyraphaga and its host called Plesiometa argyra. The parasitic wasps are able to paralyze their hosts by stinging them. After this, the wasps lay an egg in the spider’s abdomen. After the egg develops into a larva, it starts to manipulate its host. This is done by the larva injecting chemicals to change the spider’s behavior. This is “effectively turning it into the larva’s slave” (page 101). Now, the spider does not build its normal circular webs. Instead, it goes back and forth (in as many as 40 times) and builds a special web to protect the larva’s cocoon. The larva then kills the spider and sucks it dry. Finally, it spins a cocoon around itself and after about a week and a half an adult wasp emerges out of it. This relates to Big Idea 4 (biological systems interact, and these systems and their interactions possess complex properties) because the Hymenoepimecis argyraphaga and Plesiometa argyra are interacting with each other, while showing a parasitic relationship.
ReplyDeleteThe manipulation of the host is essential for the development and growth of the parasitic wasp. In order to initially develop, the wasp needs nutrients from an outside source. So, it feeds off the blood of the spider in order for it to grow. The parasitic wasp also uses the spider for protection so it does not get hurt from other organisms. Without the host, the parasitic wasp would not have the nutrients or protection to develop.
Parasitism has multiple effects on a population. First off, they can act as prey or predators in a population. Some organisms eat certain parasites. Also, when an infected host gets eaten, parasites can be prey. If the damage done to a host results in disease, then the parasite can be very negative to the population. This is because the disease can potentially infect other organisms. However, parasites have generally negative effects on populations and food chains because of their adverse effects on organisms. For protection against parasites, organisms can have non-specific and specific defenses. For example, humans have skin and sweat glands to prevent parasites from growing on their bodies. These parasites that evade or overcome the relatively nonspecific constitutive defenses are usually susceptible to the more specific inducible defenses, once they have been developed” (bacteriology). Parasites in the bloodstream, for instance, can get antibodies made to attach on to them so macrophages can undergo phagocytosis on them (this relates to unit 12).
http://textbookofbacteriology.net/themicrobialworld/NHPR.html
Tyler Hagen-thagen4@students.d125.org