 Hi, welcome to the first class of integrated pest management. Before getting into the applied aspect about how to manage a pest in an agricultural ecosystem, let us first look at the basic science about the insects, their abundance and the diversity. We all know that insects as a group are more successful organisms on the planet. It is true if you look at the tremendous success relative to the other organisms other than human beings and their extreme importance from the human point of view. How do you measure the success of insects? One of the airsticks for measuring their success is the number of extant species that means existing species on the planet. Insects probably outnumber all the species of other animals and the plants combined. It has been estimated that there are nearly 10 million species of insects and out of which we only know about 1 million species of insects. Another airsticks for measuring their success is their adaptations and it is quite phenomenal. So insects are most abundant and quite adopted to every conceivable places on the terrestrial habitat. If you look at this pie chart which gives the glimpse of about the number of extant species in relation to the other organisms. Nearly 1 lakh species of insects which have been identified will take a lion's share when compared to the description which is made in other organisms including the plants. Fishes which occupies a major habitat on the universe like water were also no match for the insect diversity and of course birds and animals are also very few. And this diagram will further strengthens and tells the abundance of the insects which speaks about their diversity when compared to all other organisms. Now what exactly the position of the insects in an animal kingdom? So let us look at its position. The animal kingdom can be broadly categorized as vertebrates and invertebrates and insects which comes under the phylum Arthropoda. So mainly belongs to an invertebrate group and it shares with the other sister groups such as arachnids, the crustaceans and myriapods. Now what are the reasons for such a tremendous success especially for the insects? Actually the Darwin's theory of evolution through natural selection which has 5 premises will very well fit into the insects as in successful groups. Let us look at one by one. The insects have got a very high natality rate indicating that their birth rate is higher than the death rate. So the many more individuals are born in each generation then actually they survive and reproduce and insects are highly variable because each individuals will have a variable characters which is not identical to their other individuals and insects also have a very high survivorship. The individuals with certain characteristics have a better chance of survival and reproduction when compared to the other characters and some of these characters of the insects are quite heritable since these characters are what is called transfer to the next generation and those characters are going to stay with that generation. And more important is they have got a time at their advantage as these insects are available or originated long ago and which has made them for a slower and steady evolutionary process. Remember the insects as attacks on have a very long inhabited this planet. Now let us look into the time of events of these things. So if you look at the earth which has actually is 4.5 billion years old and the first living cells in the form of a single cell creature like prokaryotes have originated during the P. Cambrian period around 3.1 billion year ago and the multicellular organisms have first started 600 million year ago during Cambrian period and the arthropods which are the mothers of the insects we can say were actually moved from aquatic ecosystem to the land ecosystem around 425 million years ago during Celerian period and we have in first evidence of the true insects around Devonian period which is around 400 million years ago. And at 3.45 million years ago the first great radiation of insects came which is at Carboniferous period and second great radiation of insects happened at 135 million years ago during Cretaceous period. I will explain about these two great radiations in the coming slides and we know that in comparison with the insects so around 63 million years ago that is in tertiary period. So it was dominated by mammals, birds along with insects and we the human beings hardly evolved since 2 million years ago and this diagram will again speaks about the evolution of insects in close relation to the other organisms such as myriapods and the crustaceans which are the sister groups of insects so which started around 400 million years ago. And if you look at the dinosaurs which started in the middle and then become extinct and compared to the man who has most recently evolved. I was telling you about the great radiations of the insects which took place during the course of evolution you look at like when the insects started on the earth. So in fact they were quite primitive in terms of not having the wings. So we let us look at the macro evolutionary process of the insect a little bit. So insect macro evolution if you look at that the first group of insects which were actually wingless and which are referred as a teregotens and which were originated during 400 million years ago during Devonian period and quite surprisingly some of these groups such as the silver fish then spring tails along with proturans and dipluorans are still existing. The first great radiation of insect took place by the possession of the wings and in fact we know that the insects are the first invertebrates who actually developed wings and capable of flying and thus group of insects we call them as the teregotens. And in this teregot group in fact the earlier insects like the dragonflies, damselflies and the mayflies are referred as paleopterans as they do not have the capability of folding their wings and it was a little bit disadvantageous. And the second great radiation of insect took place with a very little modification as a wing flexing mechanism that means they developed a mechanism of folding the wings and with this slight modification the insects could actually exploit smaller places and escape from the predators and having a better survivorship. So they are referred as the neopterous group and you will be surprised to know that nearly 97% of the species which are existing today will comes under the neopterous group. Now coming back to the classification of the insect in the animal kingdom I was telling you about the position of the insects and this insects which comes under the arthropoda are closely related to the arachnids, crustaceans and the myriapods. Arachnids which commonly include the scorpions, mites, then the spiders and the ticks whereas the crustaceans includes the crayfish, crabs, lobsters and the myriapodans which mainly have the centipedes and the millipedes. And all these four sister groups along with the insects will share certain common characters which are a characteristic feature of the arthropods. What are the characteristic feature of arthropods? Arthropods can be broadly divided as an arthropoda and poda. Arthropoda means the jointed and poda means the appendage or the legs and all these groups have got the jointed or segmented body and paired and segmented appendages. And these appendages are bilaterally symmetrical and they have been provided with an exo-critical which is a special cuticular structure which is made up of chitin which is periodically shed. And they have an open circulatory system unlike our higher animals which have got a closed circulatory system and the body cavity is not true. And how can we differentiate the insects as a group from the other sister groups? There are three to four basic characters by which anybody can identify an organism as an insect. Let us look at what are those characters. So insect basically have got three body divisions as a head, thorax and abdomen and these head, thorax and abdomen are easily distinguishable. Then all these insects have got three pairs of legs or six legs that is why we refer them as hexapoda. Hexa means six, poda means legs and each pair of these legs arise from each of the thoracic segment. And they also have a pair of antenna which is situated on the head which acts as a sensory structure and majority of the insects will possess the wings either one pair or two pairs of wings and with these characters it is quite possible to identify the insects. Thank you.