What Purpose Do Mosquitoes Serve? By Elizabeth Miller Mosquitoes seem to serve no purpose other to annoy us. But from the mosquitoes\’ point of view, their
is to make more mosquitoes. From the point of view of birds, fishes, frogs and other animals that eat them, their purpose is to provide a source of food. But does the world actually need mosquitoes? It\’s hard to find a reason. An article by Janet Fang in the July 2010 magazine asked scientists what the world would be like without mosquitoes. Most of them thought that we wouldn\’t miss the annoying little creatures. Disease among humans would decrease, if the mosquitoes that spread malaria, dengue fever, encephalitis and other illnesses disappeared. In the Arctic tundra, mosquitoes form dense clouds when they hatch. Birds which nest in that region might miss them as a source of food, if they disappeared. But other scientists say that mosquitoes don\’t make up a large enough part of the birds\’ diets, and they could survive on midges or other insects just as well. Caribou, which must deal with the onslaught of the mosquitoes, might change their paths, feeding in new places, and alter the ecosystem in localized areas of the Arctic. Elsewhere, frogs, lizards, spiders and other animals that eat mosquito larvae or adult mosquitoes would lose a food source. Mosquitoes make up a small part of the diet of some, but others, like the mosquitofish or gambusia, which specializes in eating the larvae, might become extinct. But most animals already eat enough of something else, or could change their diet, so they wouldn\’t go hungry without mosquitoes. Mosquito larvae consume a lot of organic matter in wetlands, helping recycle nutrients back into the ecosystem, but other larvae and water-dwelling creatures also do the same and could take over that job. Adult mosquitoes feed on nectar as well as blood–in fact, nectar is all the adult males eat–so some plants might suffer due to lack of pollinators if mosquitoes stopped visiting, especially northern orchids.
Though this might alter things somewhat, the plants aren\’t necessarily crucial to the ecosystem. The biggest effect, is that fewer people would die of mosquito-spread diseases, so there would be more humans on the earth, especially in countries that are already having trouble supporting their populations. But humans would be healthier, more productive, and not have to spend so much time and effort caring for those who were sick. \”The romantic notion of every creature having a vital place in nature may not be enough to plead the mosquito\’s case,\” Janet Fang concludes, in the Nature article. \”It is the limitations of mosquito-killing methods, not the limitations of intent, that make a world without mosquitoes unlikely. \” Of course, when imagining a world without mosquitoes, one must imagine that they were killed in a way that was harmless to other creatures, and that\’s part of the reason we can\’t just eliminate them, as much as we\’d like to. Insecticides kill not only mosquitoes, but other animals too. Even specially targeted natural larvicides, like those using kill a few closely related species such as black flies and gnats. So even though mosquitoes don\’t seem to have a purpose, other than to cause us annoyance and misery, we can\’t just get rid of them right now, without doing more harm to other species that are more useful. More articles: Images courtesy of acscom at Stock. xchng and at freedigitalphotos. net. Malaria kills hundreds of thousands of people every year and is a disease caused by parasitic microoorganisms, which mosquitoes unwittingly pass from one human to another as they move from one meal to the next. Feasting on blood is vital for the females of most mosquito species, as they need the proteins it contains to produce eggs. They can prey on animals and humans but it is those that prefer to make a meal of people known as anthropophilics that are the most efficient transmitters of malaria through their bites.
Female mosquitoes of the bloodsucking species are adapted to piercing skin and drinking blood, with a long proboscis for feeding helped by an injection of saliva that stops the blood from clotting and an abdomen that can swell to receive large amounts of blood, allowing the insect to potentially triple its body weight. Anatomically but genetically they have evolved thanks to their ability to breed quickly and produce thousands of offspring. This is now threatening worldwide progress on malaria prevention because some mosquitoes are developing resistance to pesticides, one of the main measures used to protect humans from being bitten. , from the London School of Hygiene and Tropical Medicine, is one scientist who is trying to find some answers. We re now seeing this resistance spread across sub-Saharan Africa like wildfire and this is a big problem, he says. The stuff that was killing mosquitoes before is no longer killing them and we re in a bit of trouble because we don t have any insecticides that are ready to be used and probably won t be ready to use for at least another five years. Studying an insect that can transmit the world s most deadly disease is highly dangerous and it is also difficult to observe mosquitoes natural behaviour under artificial conditions, but Dr Logan has had some successes as he tells the BBC s programme in the video clip above. The age old question of why some people get bitten while others escape has been attributed to a person s body odour, some people s sweat simply smells better to mosquitoes. Additionally Dr Logan has. Furthermore, by studying pairs of genetically similar identical twins and genetically different non-identical twins and their attractiveness to mosquitoes Dr Logan has. We found that identical twins were the same level of attractiveness, some of them were really attractive, some of them weren t very attractive, but they were the same as each other.
In the non-identical twins, that differed between twin pairs, he says. That gives us a level of heritability that is the equivalent of things like height and IQ which we know very well are passed on through your genes, so it s quite a strong trait. If the genes that produce the repellents can be identified, Dr Logan says it could lead to new drugs to protect against biting insects and bespoke ways to control mosquitoes. If we know which genes are involved in producing these natural repellents, we should be able to screen populations and be able to tell people what level of risk they are so that we can then target control measures, he tells BBC Earth. But the mosquito is only half of this particular problem, the parasites that cause malaria have changed as well and have become resistant to some anti-malaria drugs. The malaria parasite is known as nature s shape shifter, it changes all the time and it s highly evolved to do that which is why it s such a big problem, explains Dr Logan. The parasites are also able to manipulate the behaviour of their insect hosts and Dr Logan has. He says they become super-sensing mosquitoes due to the parasite changing their sense of smell, meaning humans are more likely to be bitten by an infected mosquito, which enhances the parasite\’s chances of transmission. Dr Logan says that further investigations into how the parasite does this could help identify new attractive substances which could improve mosquito trapping techniques, but ultimately he admits mosquitoes and malaria still retain the evolutionary advantage. This is one of the most challenging systems to work with. We re getting to understand it but we still don t understand it and it will probably continue to evolve, says Dr Logan. It s a bit of an arms race because at the moment the mosquito and the parasite always seem to be one step ahead of us and they re always evolving so we re playing catch up. You can follow BBC Earth on, and.