Abstract
A knowledge of insect biodiversity and patterns of distribution becomes necessary for a better understanding of insect ecology and behavior, as well as to design sampling programs for rapidly assessing pest density and phenological forecasting. In the state of Tamil Nadu about 62 species of acridids or short horned grasshoppers (Order: Orthoptera; Family: Pyrgomorphidae and Acrididae) have so far been recorded. Inventorying of acridids was carried out by surveying, sorting, cataloguing, quantifying and mapping of entities such as individuals, populations, species, habitats and ecosystems. The resulting data were used for further analysis of various parameters of biodiversity. The acridids recorded in Tamil Nadu inhabit a wide range of ecosystems. The present study was focused towards the acridid biodiversity in Tamil Nadu, their occurrence, distribution, richness and abundance from different vegetation sites viz., wasteland, grassland, forestland, and cropland as well as at different altitudes. From the 58 selected study sites in Tamil Nadu, over a period of 24 months, a total of 37 species belonging to 2 families and 11 subfamilies were recorded during the period of survey. The study depicted maximum species richness in forest ecosystem followed by wasteland, grassland and cropland. The diversity decreased with increase in altitude reaching a peak at 1100 MSL. A insignificant positive correlation was obtained between species richness for the longitudinal gradients and a negative correlation was obtained between species richness and the latitudinal gradients, while a significant negative correlation was observed with the altitudinal gradients.
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