University of Agricultural Sciences, Bangalore

Insects are one of the most versatile and fascinating groups among all the animals. They have dominated the earth and excel all other animals in both diversity and magnitude. There are atleast three times as many species of insects as of all other animals combined. They are the most ubiquitous of all animals and are virtually found wherever life can exist. There are insects living in the Himalayas, at freezing temperatures in the inhospitable wastes of antractica, on the burning dunes of deserts, in hot water (60 c) springs and burrowned far underground. A few species occur in salt water, and quite a number of them occur in fresh water, but insects are essentially a terrestrial group. In size, they vary from microscopic beetles which can easily pass through the eye of a needle, to large moths, with wing span of more than 32 cm.

Physical and mechanical control were one of the methods to be used for reduciing the incidence of insect pests. Drying of grains before storage, handpicking of lice and collection and destruction of pest-infested plant parts were the routine methods that were employed since long. Similarly, some legal measures were also adopted to overcome certain pests which were otherwise difficult to contain. For example, as early as 1911, removal of cotton sticks by 1as august every year was made compulsory by law to minimise the incidence of pink bollworm on cotton in the erstwhile madras state. All these methods were improved and refined to enhance their efficiancy against various insect pests.

In the history of the world, no century can match the population growth of the one that has just come to a close. We entered the 20th centur with less than 2 billion people and left it with more than 6 billion. The global population reached 6.70 billion in mid-2008 and is likely to reach 9.35 billion towards the moddle of the 21 st centrury. It has been estimated that the population may grow even more in the 21 st century, but in a different manner. The developed countries, which almost doubled their population size in the 20th century, will grow slowly or not at all. The new century's growth will occur almost exclusively in the developing countries. India would overtake china by 2050 to occupy the first position with a population of 1.75 billion followed by china with 1.44 billion people. The population growth will tax food supplies and outstrip countries efforts in many areas. It is thus clear that the world's farmers will need to production in the 20the century have caused many environmetnal, economic and social problems. Therefore, we face a gigantic task of ensuring environmental and food security in the twenty-first century.

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