Insects affect man’s welfare in many ways.Many insects are beneficial to man.Beneficial insects are divided into two main groups according to the nature of benefit derived from them.They are Productive and Helpful insects.
⚫ Productive insects
These insects produce certain substances which are useful to humans.The important insect products are Honey,Silk and Lac.
Honey bees are social insects.They line as colonies.They are active throughout the year.They feed on the pollen and nectar of flowers.The honey bees collect nectar from various flowers.The nectar is swallowed by the bees.In its stomach due to the action of enzymes certain changes happen to the nectar.Later in the bee hive it is collected and stored in Chambers as honey.Apiculture or bee keeping is the technique of rearing honey bees for honey and wax from their comb or beehives.
Honey has a high nutritive value.Its colour and smell varies in accordance with the nectar collected from different flowers.One gram of honey provides approximately 33k.cal of energy.It is used in Ayurvedic and Unani systems of medicines.It us helpful in building up the haemoglobin of the blood.It prevents cough,cold and fever.
Beewax is also a natural secretion of the worker bee from the glands located in the abdomen.It is used in the manufacture of cosmetics,face creams,paints, ointments, plastic works,polishes,carbon paper and many other lubricants.It is also used in microtomy for block preparation of tissues.
Silk is another valuable product from the insect world.The silk is obtained as fine threads from the cocoons of various species of silkworms.Sericulture is the scientific management of production and marketing of natural silk from silkworms.The caterpillar of this worm feeds on castor leaves.The cocoons of this worm have very loose texture and the silk produced is called as Arandi silk locally.The threads are not glossy but much durable.
The sericulture plays a significant role in the rural economy of our country.The Chinese have the credit of discovering silk.It was kept as a secret for several centuries.
The raw silk is used in the manufacture of woven materials,knitted fabrics and garments.It is also used in parachutes, fishing lines,as sieves in flour Mills, insulation coil for telephones and wireless receivers,and tyres of racing cars.
Another useful product we get from insects is lac.Lac is the recinous protective secretion produced by a kind of scale insect Called Laccifer lacca.The minute red coloured larva of this insect,settles on succulent shoots of the host plants.While growing they secrete a resinous material which covers them.The twigs are harvested and the encrustations scraped,dried and processed to yield the lac of commerce.
Lac is one of the most versatile natural resinous material.It has a unique combination of properties which render it useful in the plastics,epectrical,leather,wood finishing and other industries.It is a principal ingredient of sealing wax.
⚫ Helpful insects
This category of insects all forms which by their life activities help man in controlling the plant and animal pests.
These are generally larger than their prey.They can pounce upon and devour the prey easily.Amomg the insect predators,lady bird beetles are more useful to the farmers and gardeners.These small beetles are voracious and are highly prolific and long lived.Both larvae and adults feed on a wide range of insects.
⭐ Insect parasites
Insect parasites are smaller than their hosts.They live continuously for at least a part of their lifecycle on or within the body of the host.The braconids are a large group of small wasp like insects that parasitize a wide range of insects including plant lice and caterpillars.Most group of insects are plagued by ichneumon parasites.Employing insect predators and parasites for controlling the population of insect pests is known as biological control.
⭐ Insects as pollinators
Insects play an important role in the pollination of plants.Bees,wasps,ants,butterflies, beetles and thrips render valuable service in pollination.The services of honey bees are needed in the production of cultivated crops,such as apples,pears,plums and vegetables.Some plants like yucca and Smyrna fig are completely dependent upon insects for pollination.
⚫Other useful Insects
A number of insects feed on plants and they may aid in keeping plant weeds under control.The most successful use of an insect in the control of a plant was the introduction of the caterpillar of a moth to control the prickly pear.