Comparison of insect biodiversity between organic and conventional plantations in Kodagu, Karnataka, India

Abstract

We undertook a comparative analysis of ground insects and fruit eating butterflies on 29 different plantations in Kodagu District of Karnataka which is one of the rich biodiversity zones of the Western Ghats. These included organic and conventional coffee and cardamom plantations using different levels of chemical fertilizers and pesticides. A total number of 457 ground insect species were collected using pit-fall traps which included 92 species of ants and 123 species of beetles, among other insect taxa that we measured. Similarly, 25 species of butterflies belonging to the family Nymphalidae were collected using bait traps. We found a clear negative effect on the ground insect species diversity (Shannon index) and evenness (Shannon evenness index) in pesticide treated plantations as compared to the organic plantations. A similar negative effect was observed for butterfly diversity in plantations using pesticides. Our results corroborate the value of organic plantations in supporting higher levels of biodiversity.