GEOGRAPHICAL AND SEASONAL VARIATION EFFECTS ON DIVERSITY AND ABUNDANCE OF ACRIDIDS FAUNA (ORTHOPETRA: ACRIDIDAE) FROM COIMBATORE, T.N., INDIAMuthu Suganya and Kannayiram Manimegalai
Grasshoppers are highly diversified in grasslands and considered for both ecological and conservation importance. This study was evaluated to describe the geographical and seasonal variation of acridids community in Coimbatore, Tamil Nadu, India. Acridids were sampled using sweep net and handpicking method. Different diversity indices were calculated to estimate the acridids diversity and abundances in different environmental zone as well as different season using PAST software. A total of 2966 acridids belonging to 21 species, 15 genera and 12 tribes are under eight subfamilies were recorded. Among the 21 species of acridids, dominant species were Spathosternum prasiniferum, Trilophidia annulata, Leva indica, Acrotylus patrulis, Oxya japonica japonica, Oedaleus abruptus and Phlaeoba infumata found in all the zones as well as all the seasons. Spathosternum prasiniferum was found to be the most dominant species (D = 20.97) compared to other species of acridids. Oedipodinae was the most species rich subfamily, amounting 41.37% of total collected species. Species abundances and richness were higher in zone I (D = 41.34) compared to zone III (D = 30.45) and zone II (D= 28.22). Higher species diversity and composition of acridids were recorded in pre-monsoon season (D = 39.48). Principal component analysis also revealed that the most of the species studied were closer to zone I and pre-monsoon season. Shannon diversity index and Margalef richness were higher in zone 1 (2.67 and 3.07) during pre-monsoon and lowest in zone II (1.87 and 1.54) during summer. Renyi diversity shows that species were distributed more equitably in zone II (8.59) followed by zone III (7.39) and zone I (6.18) and ï¡-diversity was recorded highest during pre-monsoon (8.82) compared to other seasons. Statistical analysis infers that the interaction between species, environmental zones and seasons have significant effect on abundance percentage of acridid populations.