My Science School

Scientists are not sure. Mosquitoes are not known for eating waste. They don’t improve the soil like earthworms do. Yes, frogs prey on mosquitoes, but it is not their major food source. Mosquitoes pollinate plants since the males drink nectar, but they don’t do a lot of it.

Winegard thinks that may be mosquitoes have evolved to check the uncontrolled human population growth. But no one will accept that theory. Others say they have been put on earth to tell us that we are not as mighty as we think we are. We can be brought down by a tiny insect army. Do you agree?

So do we eradicate all mosquitoes? Biologists say they are part of the ecological cycle, so we cannot. They are there for a purpose, for balance in the eco-system. Who knows, maybe if we kill off all the mosquitoes, we may upset this balance and the natural selection of species. Winegard also points out: “Since there are 3,500 mosquito species and very few transmit diseases, perhaps the eradication of those that transmit diseases is extreme.”

 

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Why mosquitoes bite and what to do:

• According to studies, mosquitoes prefer blood type O over A, B or a mix of any of them. So if your blood type is O, you find more of the insects buzzing around you.


• Mosquitoes are attracted to bright colours.


• Mosquitoes like the smell of beer in beer drinkers.


• When you exercise, you let out a lot of carbon dioxide. Mosquitoes thrive on CO2.


• Our skin usually keeps us safe from mosquitoes, but you know they attack your legs. That is because of the bacteria on your feet.


• All this information about what is good for them is genetically coded into the mosquito brain. So the insect knows where to find food.

What you can do:

• Sleep under a net if your area is mosquito-prone.


• Keep surroundings clean to prevent them from breeding.


• Keep your feet covered in places like the park, bus stands, railway stations, movie halls.


• Wash your feet well when you reach home after school, before sitting down at the table to study.

 

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Mosquitoes buzzed around even when dinosaurs roamed the earth. By sucking blood and carrying parasites of crippling diseases, these creatures have ravaged human populations, especially in Africa. Mosquito bites have caused the death and disability of millions of people, ruining the economy of some countries:

Weaponized

Mosquitoes have been used as a biological weapon during wars. According to Winegard, the Nazis purposely re-flooded the Pontine Marshes around Rome and Naples in Italy to reintroduce mosquitoes, and they spread malaria in that part of Italy during World War II. The soldiers fighting the Nazis got malaria and had to be sent back.

With all the science and technology we have now, why are we not eradicating mosquitoes?

Here is why:

They’re everywhere

Mosquitoes are everywhere – in swamps, forests, fields and homes – 110 trillion of them. They are global, and have been around for 100 million years. They are great survivors, “masters of evolutionary adaptation.” They are resilient, which means they can adapt to different weather conditions and terrains. They withstood “global showers” of DDT spray, and five types of mosquitoes are now immune to this pesticide. We all have defences in our body against disease. In the same way, mosquitoes have developed immunity to survive our attempts to kill them off.

Untiring work

Still, a lot of work has been done to tackle this relentless insect. Funding is available for research on mosquito-borne disease. Mosquito nets are given out in large numbers to people. Insecticides and malaria drugs are distributed in counties that cannot afford them. Doctors say death from malaria, the major disease caused by mosquitoes, has decreased across the world. However, there is an increase in the incidence of Zika, West Nile, and dengue.

Governments are low trying biological control of mosquitoes. This is to avoid use of pesticides. In this method, fish are bred in ponds where mosquitoes lay eggs. The fish eat the larvae. There are also plants that kill mosquito larvae. But these have had only limited success in keeping down mosquito numbers.

Climate crisis

Mosquitoes thrive when we create the right environment for them – by rearing animals and plants close to our homes, cutting down trees, letting water stagnate and keeping sewage channels open. Climate change, which is now a serious crisis, also helps breed mosquitoes. “Increased temperatures mean a longer breeding season for mosquitoes,” said Winegard in an interview.

“Canada has seen a 10% increase in mosquito-borne disease in the last 20 years. In the southern US, we’ve seen domestic cases of Zika, chikungunya, and even dengue in the last 10 years. So if temperatures rise around the planet, which increases the risk of spreading disease.”

 

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The mosquito transmits or carries more diseases than any other insect. The six major ones spread by it are: malaria, dengue fever, chikungunya, zika fever, lymphatic filariasis and Japanese encephalitis.

Different species of the mosquito cause different illnesses. Research into human civilisation shows that mosquito-borne diseases throughout history have killed more people than man-made weapons.

In the book: The Mosquito: A Human History of Our Deadliest Predator, historian Timothy Winegard gives us this startling fact: over the course of 200,000 years, 108 billion people have lived on Earth. Of these, 52 billion have been killed by mosquitoes. Since 2000, an average of 2 million people have died due to diseases caused by mosquitoes. And so, it is safe to sat, the insect has had a disastrous effect on our civilisation.

 

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Ants are some of the most skilful architects of the animal world, building a vast network of chambers under the ground. They have no blueprint to speak of, and no visible leader! They also work in total darkness.

An ant expert, Walter Tschinkel, made casts of ant colonies by pouring plaster, wax or molten metal into the hollows. He observed that most chambers were close to the surface, with smaller, more spaced-out rooms farther away. How ants gauge depth is not known, but Tschinkel thinks they can sense the carbon dioxide content of the soil. The amount of carbon dioxide increases as one goes deeper underground.

 

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It might sound like something out of a horror story, but the aptly-named bone-house wasp builds its nest out of dead ants! It stuffs the ant bodies between the mud walls of its nest. Scientists discovered that the corpses not only provided insulation from heat and cold that the scent kept away a number of predators. Most animals avoid ant colonies because they are known to put up a ferocious defence against intruders.

Scientists theorized the reasoning behind these strange defense tactics and concluded that the wasps are using the ant carcasses as deterrents from possible predators. Ants emanate strong pheromones as communication mechanisms and these scents linger for a period of time after their death. The smell of the lifeless bodies serves as an adequate deterrent for animals attempting to eat nesting larvae.

This analysis results in the subsequent reasoning that female wasps must actively seek out and kill live ants as opposed to collecting their dead bodies. This theory was confirmed by the 13% lower parasitism rates in bone-house nest as compared to nests of similar species.

 

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We all know that spiders make webs but the Australian leaf-curling spider builds two additional houses to provide her with a den as well as a nursery for her babies. After making a web, the female chooses a suitable dead leaf. She lines the leaf with spider silk and curls it to form a little den that is closed at the top and open at the bottom. She hangs it in the centre of the web and waits inside for passing prey.

When she is expecting babies, she curls another leaf and hangs it away from the web in the midst of foliage.

The spider is also eco-aware! She uses not just fallen leaves but also discarded scraps of paper or other waste material to make her shelters.

 

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The female of the montezuma oropendola of Central America builds one of the most elaborate nests in the animal kingdom. Using vines, the bird weaves a large basket-like nest that hangs from trees. The nests are anchored with the strongest vines, and bits of fibre and other vines are added as finishing touches. They are built in a group, forming a huge colony.

To keep away predators, nests are constructed on isolated trees and are suspended from the flimsy ends of the branches to deter monkeys. The oropendolas also take care to locate their nests inhabited by hornets!

 

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Four species of solitary bees in Turkey and Iran make a three-tiered shallow underground nest called a ‘flower sandwich’. The outside layer is made of petals, and then a lining of mud is applied, ending with a layer of petals for the innermost chamber. A store of nectar and pollen is deposited in his chamber for the larva to eat when it hatches. The egg is laid and the chamber is sealed by bending the petals forward and slathering the whole thing with mud! Each bee bower has room for just one egg.

The sandwich keeps the larva’s food moist. When the baby bee has eaten, it spins a cocoon and hibernates for ten months. By the time spring arrives, the chamber hardens like a nut, protecting the bee from predators and from collapsing inwards.

The bees emerge only to mate, build another nest and lay an egg, before they die.

Scientists found that the bees in Turkey pick pink, yellow, blue and purple petals while the ones in Iran favour only purple!

 

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