BEPLS Vol 6 Spl issue [1] 2017 101 | P age ©2017 AELS, INDIA Bulletin of Environment, Pharmacology and Life Sciences Bull. Env. Pharmacol. Life Sci., Vol 6 Special issue [3] 2017: 101-105 ©2017 Academy for Environment and Life Sciences, India Online ISSN 2277-1808 Journal’s URL:http://www.bepls.com CODEN: BEPLAD Global Impact Factor 0.533 Universal Impact Factor 0.9804 NAAS Rating 4.95 FULL LENGTH ARTICLE OPEN ACCESS Insect Biodiversity: The Teeming Millions- A review E. Sankarganesh Department of Entomology, School of Crop protection, College of Post Graduate Studies, Central Agricultural University, Umiam, Meghalaya – 793103. ABSTRACT Insects are the world’s most diverse group of animals on Earth, in terms of both taxonomic diversity and ecological function accounting 75 % of the known species of animals.Approximately 30 million species are found worldwide, of which about 1.4 million have been briefly described.Less than 3% of all species of insects have aquatic stages in some freshwater biotopes. India is one among the twelve mega biodiversity countries of the world, constitute nearly 7% of the world insect fauna. Current estimate shows that out of nearly 63,760 species of insect species in India, about 21,166 species are endemic. The diversity of insects is greater in the north-eastern states, the Western Ghats and the Andaman and Nicobar Islands, and these areas also have a high level of endemism. Insects are becoming extinct because of habitat loss, over-exploitation, pollution, overpopulation and the threat of global climatic changes. Insect biodiversity has a significant role in the maintenance of the ecosystem. So, there is increasing need for taxonomic information and services in our society, particularly for biodiversity assessment for attaining an environmentally sustainable future. Several biodiversity indices were used to study the species richness in the area. With the recent advancement in science, the new method called DNA barcoding, a tool of DNA-based taxonomy is used to identify known and unknown species on the basis of the pattern of nucleotide arrangement in a fragment of DNA from target species. In order to speed up taxonomic identification, DNA barcoding is now been considered as an alternative tool for insect biodiversity identification in India and the World. Keywords: Biodiversity, Insects, Ecosystem, India, Taxonomy, DNA barcoding. Received 13.07.2017 Revised 09.08.2017 Accepted 23.08. 2017 INTRODUCTION Biodiversity in the recent years has acquired considerable importance as focal point ofdiscussion like some other global issues (Ghosh and Singh, 2000). It means the variability among the living organisms from all sources, diversity within species, between species, and of ecosystems. (Harper and Hawksworth, 1994).Usually biodiversity is considered has three levels genetic diversity, species diversity and ecosystem diversity (Solbrig, 1991).Insects represent the vast majority of species in terrestrial and freshwater ecosystem. They have adopted for almost every conceivable type of environment from the equator to the arctic and from sea level to the snowfield of highest mountains, on land, in air and water (Belamkar and Jadesh, 2014). Evolution of Insects Biodiversity is not static, it is a system in constant evolution from a species, as well as from an individual organism point of view. The average half-life of a species is estimated at between one and four million years, and 99% of the species that have ever lived on earth are today extinct. Biodiversity is not distributed evenly on earth, it is evident from fossilized specimens that insects were living 400 million years ago. Evolution of insects in our universe is classified as Silurian, Carboniferous, Late carboniferous or earlyPermian, Paleozoic and Cretaceous periods (Gullan and Cranston, 2005). Diversity of Insects Biologists have long realized the great diversity of insects. But the described insects are unknown fraction of total, no central organized database for the life on earth and also unclear how many described species exist (ZSI, 2012).Approximately 30 million species are found worldwide, of which about 1.4 million have been briefly described. (Balakrishnanet al., 2014).The kingdom Animalia is represented by 15, 52,319 species that have been described so far globally in 40 phyla in a new evolutionary classification. The phylum Arthropoda alone includes 12, 42,040 species, constituting about 80% of the total number of