Wednesday, March 23, 2011

Mosquitos

Nobody really enjoys having those itchy, swollen spots from getting bitten by a mosquito. During the height of summer, almost everyone finds them cursing the fact mosquito exist at least once. Many people may even entertain the idea of getting rid of them so they wouldn't go around biting people. But as any biologist knows, eliminating one species can have a dire ripple effect on the rest of their ecosystem. However, writers for Nature** recently asked scientists how big the ripple effect would be if we were to get rid of mosquitoes from the world.

Like many things, this hypothetical really depends on where you are looking at. The importance of mosquitoes varies from ecosystem to ecosystem, something that is fairly intuitive. One prime example provided in the article is that of the Arctic tundra. In the Arctic, mosquitoes have an annual hatching where there are massive numbers of adults for a short span of time. These mosquito swarms not only act as a food base for many birds and fish, but also they have a direct effect of the paths that caribou take on their migrations, in order to avoid these choking swarms of bloodsuckers. The removal of these mosquitoes may serve to devastate the stability of the Arctic tundra biome.

However, there aren't especially many people for mosquitoes to annoy up in the Arctic tundras, suppose that we eradicated them in a less far-removed location. What would be the consequences of that? Studies showed that many species rely on mosquitoes as a food base. This ranged from spiders, fish, other insects, and many birds that simply had a diet of which mosquitoes are fraction to very specialized predators like the mosquitofish, which (as the name implies) is a predator that predates almost exclusively on mosquitoes. An experiment done with house martins revealed that the birds averaged one more egg per nesting in areas where mosquitoes were present. However, other species such as bats have a very small gut content of mosquitoes and would not be disturbed by their removal. Many ecologists speculated that the mosquitoes were filling an easily replaceable niche that would not be particularly crippling in the larger picture when they were removed. Mosquito larvae also have a notable role in the environments they inhabit. They help decompose decaying organic matter back into nutrients which are released back into the environment. However, they are just one among many species that perform this task, and in most areas don't make up an abundant amount of the biodiversity. It is only in, again, very specific areas and ecosystems that the removal of mosquitoes would be felt with some significant gravity.

This is just the ecological part of the picture. What sort of humanitarian reasons could we have for exterminating a species entirely beyond that they are just plain annoying? Mosquitoes are what is referred to as disease vectors, that is, mosquitoes spread diseases through sucking one organisms blood then depositing in their next meal. This transfer of bodily fluids spreads all sorts of nasty contagions. Mosquitoes spread malaria, which is one of the leading causes in death in many underdeveloped countries. It claims approximately one million a year, and infects 247 million. Other diseases born on the wings of mosquitoes are dengue fever, yellow fever, Japanese encephalitis, Rift Valley fever, Chikungunya virus, and West Nile virus. Exterminating mosquitoes could potentially cripple the virulence of these diseases and save millions of lives each year, not to mention extortionate amounts of money in the department of healthcare and disease prevention. The drawback for this, of course, is having more people alive in a world that is already considered to be over carrying capacity. But it is something of a tough call to make by saying that the issue of overcrowding is worse than the horrific effects that these mosquito-borne diseases have on the world. In that respect, the article concludes with the statement that it is probably our limitations on the ability to exterminate these pesky bugs that stops us from doing so more than the dilemma of whether it will have devastating effects on the world that stops us from getting rid of mosquitoes all together.

LINK: http://www.nature.com/news/2010/100721/full/466432a.html

Posted by Reed Allen (1)

7 comments:

  1. It seems to me that the better way to go is to control the disease in a preventative way and in a treatment way that does not involve wiping out an entire species. Clearly in some areas this species is more important to the ecosystem than in others, but no matter what, weakening an ecosystem is never a good idea, especially when climate change is already stressing many ecosystems. I agree that disease must be controlled, but I think there are better and less destructive ways of doing it.

    Posted by Marlena Grasso

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  2. As its mentioned/implied in your post, mosquitoes are an issue regardless of being vectors for diseases. Since many mosquitoes have developed a resistance to pesticides, mass removal of theses insects may be impossible. Eliminating them all together is a relief for us but it can disrupt the trophic interactions going on in the environment especially for organisms that are mosquito specialists (fish, plants, herps and etc).
    Insects that carry diseases do not carry them voluntarily. Like other organisms, they undergo immune responses to counteract infections/diseases. Some insects undergo melanotic encapsulation where parasites or diseases that enter the insect are enclosed and destroyed within a melanin rich capsule. In cases of mosquitoes and malaria, a 1997 Science publication showed that A. gambiae (mosquito species) can encapsulate human malaria parasites. This was discovered by looking at specific loci involved in the trait for encapsulation. By selecting for the encapsulation trait, these mosquitoes can be used as a replacement for other mosquito populations as a malaria control strategy. Also it can reduce the effects of the elimination of mosquitoes on organisms that are mosquito dependent.

    Posted by: Nelson Milano

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  3. I'm glad you brought this topic up, it's one of those very interesting subjects like global warming or commercial fishing in that it represents a fundamental conflict of interest between humans and the environment. From the conservation side, we know too well that the blow-back from a scheduled extinction can be far worse than the maladies that came before it. Likewise, the epidemiological argument is one of great significance in the third world, and one that should be considered from the perspective of millions of poor, starving people who have very little control over their own lives. I know nothing about mosquitos, though after reading your enlightening post, I have come to a final, informed opinion on how we should approach these organisms: we should wipe them off the face of the Earth and then hold an international coctail party to celebrate.

    Yes, mosquitos do play a role in caribu, arctic wolf and avian migration routes—by inhibiting them. Mosquitos not only delay migrations routes, but invariably make the herds and flocks into a breeding grounds for blood-borne pathogens. Killing mosquitos would actually benefit conservation.

    The human epidemiologicl evidence you cite is also compelling: 1 million dead and 247 million infected per year. At that rate, the humanitarian argument alone would probably be enough to drive the UN to support mosquito extinction.

    All said and done, it appears there would be one, lone victim of the hypothetical mosquito massacre: the mosquito fish.

    I honestly feel bad for the little guy, but, to be perfectly honest, it seems like a small price to pay in the fight against Malaria.

    Posted By: Alexander Simolaris

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  4. The relationships between mosquitoes and other species is reminiscent of one between locusts and birds. However, recently in Australia, the government changed laws so that the country's farmers are required by law to poison native Australian locusts. The birds and other animals that feed on these locusts are being poisoned because of this.

    I have read about the possible implications of removing all the mosquitoes before, and some of the articles mention a butterfly effect reaching out to humans, and our possible extinction because of this. Food chains are very interesting things.

    I also must say it were possible to eliminate all mosquitoes, and it would save one million lives a year from dying of malaria, that does sound very good. I, however, have some issues with this. But before that, who are we to say overpopulation is a greater issue than malaria? We must worry about, and aim to solve, overpopulation, but separately. But, as for saving money, I wonder how much money it would take to remove all mosquitoes. And who is to say another disease would not sprout up or become widespread after the removal of mosquitoes? We could not even begin to comprehend the effects of this removal, and who are we to say we are even allowed to kill an entire species of anything?

    Posted by Derek Melzar

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  5. I feel as though this topic would never be brought up for any other species that wasn't an insect. Nobody would think of this idea twice if it involved a different species, even other insects like spiders. Yes mosquitoes are annoying, but as the article states they have a great impact on the world, both positive and negative. If the entire species was wiped out, or even relocated, there would be severe consequences for the food chain and ecosystems. There is no debate in my mind that we need to let the Earth run its own course, without us purposefully destroying a species.

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  6. I certainly agree that weakning the ecosystem is not the good idea, there are several other ways to control this particular problem. Today as we know that technology is advanced and I think scientists will come up with some solution of the problem of mosquitos or invent some kind of drug that will affect them directly without impacting the ecosystem.

    by Ammar Zafar

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  7. Nelson, I agree that that entire species should not be wiped out. For such a minor annoyance to the human population, a species should not become extinct. Many organisms rely on the mosquitoes, or even rely on organisms that rely on mosquitoes. This small action will have huge impacts world wide and over several species.

    by Reed Allen

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