Lesson 1
 

INTRODUCTORY ENTOMOLOGY

What is entomology :

  Entomology is a branch of zoology, which deals with the study of insect. The word entomology has two parts viz., Entomon = Insects and logos = study. Agril. Entomology deals with the study of insects in relation to agriculture

Importance and scope of entomology:

  Study of entomology aims at understanding insect body organization and function, their habitats, behaviours, relation to one another and to the surrounding in which they live, their classification, development distribution, post history and their economic importance.

  Man has been attracted towards insects from very early times. The Sanskrit term Shatpada refers to the hexapodous condition of insects. Use of insects and insect products as items of medicinal value (oil beetles, use of lac, use of red ants in suturing wounds) have found a place in certain indigenous systems of treatments. Honey is used more as medicine than as a food. Parts of insects have been used as cheap jewellery by certain tribes.

  As far as study of insect is concerned in agriculture it is of worth importance. Related to agriculture, insects are both useful and harmful. As a harmful role they damage our crops, lay waste vast areas of cultivated land, despoil on feed; they bring about different diseases and some of the examples are Malaria, plague, typhus, sleeping sickness etc. The serious disease malaria was earlier thought to be beyond the reach of mankind. A lot of money was just wasted in Malaria management but was of no use. When the entomologist studied the morphology and taxonomy of mosquitoes, they get interesting information on malaria transmitting mosquito, the Anopheles and the problem was solved just like anything. Another example is that of body louse spreading typhus fever in 1944 in Italy amongst the civilians living in crowded conditions. In 1939 Dr. Paul Muller discovered the insecticidal properties of DDT, which was then used in control of body louse. DDT become famous overnight as an insecticide and Muller saved thousands of soldiers from the deadly disease, typhus and not surprising, therefore that P. Muller was  awarded the Nobel prize for Medicine in 1948. These are some insects, which are of international importance as a pest e.g. Locust. To show their devasting features some statistics related to them sufficient. A swarm of locust is estimated to contain more than 1500 million individuals. They fly with a speed of 150km/day. Even sunlight can not pass on earth when they are flying. They just eat everything which is green on earth. Army worms behaves like an army and destroy the crop within an overnight. This is about the harmful role played by insect. Now some of the useful roles played by the insects are.

1. Insects are the cheap producers of some valuable natural commodities e.g. silk. Honey lac, cantharidine, tannic acid, formic acid etc.

2. Insect act as natural pollinators.

3. Insect plays viral role in biological control of other injuries insects and weeds.

4. Insects improves the physical condition of soil by a) burrowing b) by adding their dead bodies.

5. They play vital role in converting dead decaying organic material into organic manure.

6. Some insects are valuable in scientific study e.g. Drosophila; insects helps in criminal investigations especially in murder cases (Housefly maggots)

  Entomology as applied science has its own importance both in plant protection and getting benefit for mankind from the useful role played by insects. Scientific entomology is over a century old in India and a firm foundation of economic entomology has been laid by scientists like Lefroy, Fletcher, Ramkrishnan Ayyar and Ramchandra Rao in India. Till absent 1930, the subject was morphological all over the world. This study yielded considerable information on Taxonomy, insect pests and control. Towards the later period, applied entomology developed and a fundamental basis for pest study and methods of pest control including biological and legal control formed the major activity in this branch of science. Recognizing the usefulness of insect as an experimental animal Wigglesworth showed that physiology of insect is a fascinating field of study, and he established insect physiology as a separate discipline in 1930-38; in later period the same was extended into field of insect control also. In 1950-60 entomology emerged as a biological science encompassing morphology, ecology, physiology, phenology, pestology, biochemistry and ethiology (behaviour).

Scope: In their attempt to secure food insect inflict considerable damage to almost every part of the plant. The origin of insect dates back to about 350 million years ago. Of the estimated 1.35 million living species of animals more than 9,00,000 are insects. Their capacity for multiplication and wonderful adaptations has made them a serious threat to human being and his existence. They compete man for three basic needs i.e. Food, clothing and shelter. Among these food is common to both of them. Looking towards increasing population this vital item is now a days becoming scare and to secure this food man has to always think about insect as his first enemy. Due to this, entomology has its scope first in the area of plant protection. Research is continuously going on and newer insecticides are evolved as a result.

  Still the problem is not solved. And hence man is taping new feeds in plant protection. As result of this new generation pesticides were born some of them are use of harmones, antihormone coupounds, chemosterilents, antifeedant, repellants, pheromones etc. which now a days replacing use of hazardous pesticides.

  We are not yet able to identify most of the insects on earth where there may be chance of identifying a new pest. There is a scope for entomologist to identify more no of insects. Similarly scope is there for designing newer and cheaper methods of pest control because all the pesticides are toxic to human being causing several deaths every years. Also they are producing resistance in insect, where to control such a resistant progeny is a great challenge. To solve this problem upto certain extent a new technique adopted is IPM. (i.e. Integrated pest management) but still IPM for all the crops is not available here also a vast scope is there. New field called genetic engineering is coming up where one can develop pest resistant (immune) crop variety which will solve all further problems arising as a by product of pesticide use. Such work is in progress all over the world. (e.g Bt rice, transgenic cotton etc.)

  On the other hand we havenít yet able to exploit the fullest utilization of useful role of insect in agriculture. As seen earlier insect benefit to us in several ways one of it is their valuable products. Still in India the silk industry is not growing as it is growing in other countries like Japan and France this is because of lack of knowledge, excluding Karnataka other states should come up in production of silk which has a great potential in earning foreign exchange. Similarly bee keeping it yields honey and wax which are very important commodities, other then that pollution by bees is an additional advantage and farmers should take help of these pollinators to uplift their yields.

  Entomology can generate employment up to certain extent e.g. production of parasites/ predators, diseases causing agents. This job one can do by taking short training and can earn money as well as can help the farmer in adoption cheap and non polluted plant protection.

  For increasing population we will be in short of food material and to secure it  we have to do a lot of labour in this field . Where still a lot of scope is there.