Eradication of mosquitoes cannot be done without destroying the world

11/04/2016

Eradication of mosquitoes cannot be done without destroying the world

Maneka Sanjay Gandhi

(Bihar Times) Even an ahinsak like me makes an exception for the mosquito. I may not kill them myself – but I have the usual array of anti-mosquito devices to protect my house: from various versions of Goodnight to a much healthier and better smelling cowdung and camphor biscuit that we set alight every evening. In the bird pond, we have put small black fish called Gambusia which are voracious mosquito egg/larvae eaters.

Mosquitoes are the most deadly animals on the planet – as dangerous as the human being (and that is saying a lot!). They spread malaria, dengue, yellow fever, West Nile virus, Rift Valley fever. In 2015, 438,000 people died from malaria, according to WHO. 30,000 died of yellow fever and 22,000 with dengue. Mosquitoes have killed more people than warring humans. In fact, during wartime, more soldiers die of malaria than from bullets. And now comes Zika which has brought an entire subcontinent to its knees. Imagine being pregnant and finding out that, because you were bitten by a mosquito, your baby will be born with a small head and brain. The mosquitoes that have been implicated in this awful disease are day-biting mosquitoes Aedes aegypti and Aedes albopictus. Day biters are so much more dangerous than night biters because we have no protection against them at all.

And its not just humans. Dogs and cattle go crazy when mosquitoes buzz around them. Prior to the 1800s, mosquitoes did not exist on the Hawaiian Islands, so the wildlife there had no natural resistance to the diseases they can carry. When mosquitoes arrived as hitchhikers on human ships, countless species of native Hawaiian birds were decimated by diseases such as avian pox virus. And this is the story of all islands.

If the mosquito were bigger, it would be so much easier to kill. Humans have almost exterminated every large species of animal. If it were in the ground, we could deal with it as well – after all we have destroyed earthworms and thousands of other insects through our mad use of pesticides.

But it grows in temporary little puddles of water anywhere, in ponds that are not cleaned, in old tyres left in garbage dumps, in half filled tins. It travels. As the planet warms it goes higher to areas that were untouched because they had low temperatures.

Who can stop this tiny killing machine? Every day one country or another declares war on it. And that immediately brings joy to the chemical manufacturers. But nothing works. We are the only country in the world that still uses DDT and we have killed more people and birds with this chemical than mosquitoes which are immune to it.

Now that we have established that mosquitoes are the baddies of the world, what would happen if the mosquito simply disappeared – like the sparrow or the vulture? Perhaps nothing – the Greek meaning of the word Anopheles, one of the 3 worst species, is “of little use.”

Or perhaps a lot.

There are 3,500 species of mosquito and they play a major role in nature. Male mosquitoes eat nectar, becoming major pollinators of some crops and flowers—even orchids. They eat aphids which are destroyers of plants. Mosquitoes themselves feed on decaying leaves, organic debris, and microbes.

Mosquito larvae are aquatic insects. The larvae are filter feeders that strain tiny organic particles, such as unicellular algae, from the water and convert them to the tissues of their own bodies, which are, in turn, eaten by fish. Mosquito larvae feed on detritus that floats and clogs the surface of the water, keeping the detritus from choking off nitrogen and oxygen necessary to the survival of plants below. Without mosquitoes to eat away the waste, the plants and the ecosystem they support could vanish as well, since they cannot gain access to the nutrients they depend on for life.

Mosquito larvae are nutrient-packed snacks for fish and other aquatic animals. Their role on the bottom of the food chain doesn't end at the larval stage, of course. As adults, mosquitoes serve as equally nutritious meals for birds, bats, and spiders, fish, frogs, tadpoles, salamanders, spiders, lizards, turtles, dragonflies, songbirds, swallows and bats. Would bats disappear if mosquitoes did? Perhaps not, because they eat other insects as well. But other creatures could. Remove mosquitoes and the ecosystem might experience a paradigm shift; numerous species might starve out, with newer species rising up to replace them. Removing them probably does not mean the end of all life, but in a few years’ time, the ecosystem will look vastly different to the one we know today.

Scientists simply don’t know how the mosquito fits into the food chain. Research has unravelled food webs of bigger mammals, such as lions or leopards, because they are easier to observe. But no one knows the entire impact of the mosquito. Obviously, if you remove an animal from an ecosystem something will change, but can we afford it when we don’t know what? Mosquitoes populated this planet long before man; the oldest mosquito fossils date back some 200 million years, to the Cretaceous period. They seem to be an integral part of several ecosystems, since they have co-evolved with many species along the way. Presumably, sometime after large animals evolved, some insects started to take advantage of the rich nutrient source that is their blood. The insects that were best at eating vertebrate blood prospered, and their offspring, with mutations that made this task easier or more effective, prospered even more. Their distant descendants are today's mosquitoes.

What would happen if these creatures were eradicated completely? According to some ecologists, the loss of mosquitoes would harm most ecosystems. Others believe that other organisms would step in and assume mosquitoes’ role as food sources, detritivores, and pollinators.

The good part of their eradication? So many diseases would disappear, so many people would get a good night’s sleep without inhaling chemicals, and so much money that is now being spent on mosquito coils, bednets and medicines would be saved, so many hospital beds would be freed up. All good.

The bad part?

Eradication of mosquitoes cannot be done without destroying the world. If we use even more pesticides the damage to the environment would be colossal. As it is these pesticides give millions of people cancer. I would rather have malaria than cancer.

If you wanted to change the habitat you’d have to clear forests. You'd have to create a desert essentially to get rid of water sources. If you introduced a lot of predators - like fish, dragon flies – they might finish the mosquitoes but then they're going to start taking care of other things you don't want them to take care of.

Mosquitoes actually dictate ecosystems. For example, each year when the snow melts in the Arctic tundra, mosquitoes hatch from their eggs. These insects serve as an important food source for migratory birds. Mosquitoes even impact the migratory routes of caribou. As caribou move through the Arctic, they take certain routes specifically to avoid mosquito swarms. These migratory routes then impact plant distribution, dictate the feeding behaviour of wolves etc. Not just animals, mosquito-borne diseases have effectively protected people who reside in certain malaria-endemic regions from the influences of foreign intruders - whether those be military or commercial.

Elimination of mosquitoes might make the biggest ecological difference in the Arctic tundra. If that biomass vanished, the number of migratory birds that nest in the tundra could drop. In the absence of their larvae, hundreds of species of fish would have to change their diet to survive. And the loss of these or other fish could have major effects up and down the food chain. Many species of spider, salamander, lizard and frog would also lose a primary food source.
One ecological effect of eliminating mosquitoes is that you will have even more people, and an increased human population could outweigh the benefits of a healthier one. Do humans serve any meaningful purpose in nature? Is there a purpose to nature or are we all here because we have traits that allow us to survive?