Edge effect on roller dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae) in the moist South Western Ghats

Abstract

Effects of habitat fragmentation and modification, leading to creation of habitat edges is studied on the species richness and abundance parameters of the roller dung beetle population of Nelliampathi in South Western Ghats. Round the year collection of dung beetles was made employing dung baited pitfall traps in three habitats- semi-evergreen forest, agriculture habitat and the ecotone between the two habitats. The rollers represented by three genera, Paragymnopleurus sinuatus (large roller), Ochicanthon mussardi (small roller), Sisyphus araneolus (small roller) constituted the second most abundant guild (4.07%) preceded by the tunnelers. The general low abundance of rollers compared to tunnelers is attributed to the cool, moist climate which makes dung processing a difficult and energetically less efficient behavior for rollers. Species richness of rollers did not show edge effect. Two species, each was collected from ecotone (O. mussardi and S. araneolus) and forest (P. sinuatus and S. araneolus) and none from agriculture habitat. The overall abundance of rollers was low in ecotone and high in the forest. The ecotone dung beetle assemblage was essentially a diminished sample of forest assemblage and the proximity of ecotone to forest and agriculture field did not enhance its suitability as preferred habitat for roller guild of dung beetles in Nelliampathi region.