Dr Irengbam Mohendra Singh
Insects are remarkably efficient live machines, almost perfectly engineered by Nature. A mosquito can think 100 times faster than you and me. That’s why they are difficult to catch. This scientific news beggars belief. Those who have watched the World Cup football match between England and Tunisia in Russia on June 18 2018 at the Volgograd stadium, would have heard how the England player were struggling with little white flying insects, which they call ‘midges’ (pronounced midziz).
Midges is a common English word, like Manipuri Tin-kang for a group of smallest two-winged insects that include kinds of small flies. In summer, my garden with hedges at the far-end, swarms with black midges at dusk. The fly in among head hairs and bite, causing me itch.
Midges were wreaking havoc at the pitch in Volgograd as the arena stadium was built near a marshland and Volga River. FIFA sent helicopters into the night sky with special insecticide spray to try to clear the pest ahead of the next fixture.
We regard insects as nuisance, but not all of them are like that. The garden bumble bees with a band of yellow stripe on their shoulders are everybody’s favourite. They are remarkable animals. I never ever kill a bumble bee that has strayed into the house. They’re gentle, buzzing about colourful flowers, and hardly ever bite anybody.
New studies show bumble bees, despite their small brains, are inventive to solve complex problems, quickly figuring out a better way to get a sugar reward. They possess complex navigational skills, rudimentary culture, and emotions.
Bumble bees inspire many romantic poets. An old classic Manipuri song that shows a passionate display of emotions is “ mamang leikai thambal satle,/khoimuna ille khoilaba;/shabi lao lao chatsi lao;/ kalakpa yammee, kanjaoba yammee, mangda tharo lao (Lotuses are blooming in the neighbourhood, drones of black bees lay siege in the place. Hurry my love, walk ahead of me, there are many who are green-eyed).
A 1969, blockbuster Hindi cinema Aradhana (worship of a person), captures the romance of bumble bees: Gunguna rahe hain bhanware/khil rahi hai kali kali […]/Bhagon me bahar hai/safal hogi teri aradhana (The drones are humming in love/ the flowering buds are glowing in delight/ Your devotion will bear fruit).
Another insect that is frighteningly familiar with us are mosquitoes . Their brain, though very tiny (1.5 – 12.5 mm depending on size, from fossils) is fairly similar to human brain. But they can think 100 times faster than humans. Once a mosquito sees a motion, a high-speed information is relayed from their brain to the wing muscles in a fraction of nanosecond (so says research). That’s why mosquitoes are difficult to catch. Scientists still do not know why some human blood tastes better to mosquitoes. They choose who to bite, probably from smell.
Some insects like honeybees, are friends to humans. Without them you won’t be eating Shimla apples, cucumbers, onions, grapefruits. Some insects are incredibly weird, such as the rightly named ‘Assassin bug’ that has a straw-like mouth with which it injects prey with a toxin that liquefies their insides, which it then sucks it back up through its straw mouth.
Others like butterflies, are just delightful. While moths in general, bane of our expensive woollen clothes, silkmoths that have lost their ability to fly, are economically important insects. Mahatma Gandhi was against silk production because of his ahimsa philosophy. So he promoted cotton spinning wheels as well as ‘ahimsa silk’ or wild silk made from the cocoons of wild and semiwild silkmoths.
Kolkata is a good place for watching live butterflies, such as Butterfly Garden at J.B.S. Haldane Avenue. T During my college days, there was a large three-storey building full of dead butterflies at Chowringhee (now, JN Road) when Saheed Minar at the Esplanade was called Ochterlony Monument.
Some insects are like Superman. They can walk upside down on ceilings or walk up slippery glass panes. Because, the gravity pulling them down is weaker than the electromagnetic forces between the molecules of the sticky fluid they secrete on to their feet and the surface of the wall. They can fall from great heights and nothing happens to them. JBS Haldane, a British pioneering geneticist (1892-1964) wrote in his famous essay ‘On being the right size’ in 1926: “You can drop a mouse down a thousand-yard mine-shaft; and, on arriving at the bottom, it gets a slight shock and walks away, provided the ground is fairly soft. A rat is killed, a man is broken, a horse splashes. Big animals hit the ground with higher speed and higher energy, because of less air resistance.
Darwin, like many, was fascinated by the diversity of species of beetles (350,000 species) that had been in existence since the time of dinosaurs, 145 million years ago. The study of beetles is an important part of evolution. Haldane, promoting Darwinian thinking, was famous for the following quotation: “… if one could conclude as to the nature of the creator from a study of Creation, then it would appear that God has an inordinate fondness for stars and beetles…”. He aimed his statement at theologians who claimed that the nature of God could be discerned from His creation, and man, being the greatest creation of all, is created in God’s image.
Haldane, educated at Eaton College (school), and Oxford, taught at Cambridge in England, and Harvard in US. Later, he moved to India in 1957. He took Indian citizenship and headed the government Genetics and biometry Laboratory in Bhubaneswar, Orissa. He died there from cancer.
Insect fossil records date back some 480 million years. They evolved from crustaceans (see below) that lived in water. About 400 million years ago, the first insects were land-bound and one lineage evolved to fly with wings, the first animals to do so. Modern insect families appeared about 145 million years ago, about the time of the development of birds. Most modern insect species developed about 66 million years ago, called the Crustaceous period.
Recently, For the first time, researchers from the University of Maryland, US, have found ‘solid evidence’ that insects, such as beetles, honeybees, flies, ants etc. evolved from a group of crustaceans (animals with an outside skeleton), while another group evolved into today’s animals without backbones like lobsters, crabs and shrimps, and also into animals with back bones eg tortoises and turtles (their backbones and spines are fused to the bones of their shells).
Fossil records show giant insects eg Dragon flies (charang in Manipuri) as big as modern seagulls, dominated the Earth. They still dominate the planet (90% of all animal species). Over a million different species of insects have been discovered and 10 million more left to be discovered. We are lucky that their size is small, due to geometrical restrictions on their tracheal network (vide infra) because of the present low oxygen content of the atmosphere.
Insects were big, because the oxygen contents of the Earth’s atmosphere, 300 million years ago, before the evolution of the first insect, was between 30-50%; now 21%. They have no lungs and their tissues receive oxygen directly from outside through their spiracles and tracheal tubes that run along the body on the top side. As insects got larger the percentage of their bodies taken up by the tracheal system had increase to supply abundant oxygen. As this isn’t possible now, they have to reduce their size.
All insects undergo metamorphosis ie changes from egg to larva, pupa and adult. For them the three leg-bearing segments are fused into the thorax. Our common fly is a representative of all insects. Like us, it has three segments: head, thorax and abdomen. Each segment of the body has its own pair of appendages (arms and legs). Wings are thought to have evolved from the gills of their ancestors (crustaceans) while living in water. Most winged insects have two pairs of wings. In flies, the rear pair is reduced to act as stabilisers to help the insect orient itself.
Their internal body functions are quite similar to us. They breathe passively as above. Its digestive system consists of a large salivary gland, mid gut (stomach), hind gut and anus. Their circulatory system is called ‘open circulation’ ie their organs just float in blood that has no red pigment (haemolyph). They have a ‘heart’ that pumps blood, but no other blood vessels. Nutrients from the blood are transported to the cells.
The head has the mouth and two types of eyes; compound and simple. Each compound eye consists of four thousand separate lenses, providing a wide-angle vision as in a camera. They have also simple eyes called ocelli on top of their head to differentiate between light and darkness, and to detect UV and IR light patterns.
The nervous system contains the brain and the nerve cord, which runs along from head to tail. Their brain is sharp at processing visual signals, in particular with movements and chemical signals. It has good memory function. The antennae on its head serves as ears and nose, and taste. Their reproductive system in a female fly, consists of vagina and ovary. The male genitalia, located on its posterior are withdrawn when not mating. During copulation, the sperms are injected into the female reproductive system. Aren’t they amazing?
The writer is based in the UK Email: email@example.com Website: www.drimsingh.co.uk
Dr Irengbam Mohendra Singh