Dung beetle (Coleoptera: Scarabaeinae) community structure across a forest- agriculture habitat ecotonein South Western Ghats

Ecotones are zones of transition between biomes or ecosystems.Ecotones, natural or anthropogenic, can greatly affect insect community structure across habitats.Scarabaeinae dung beetles are ideal biological indicators that are used to study effects of habitat modification, fragmentation and edge effects on biodiversity. Dung beetle community structure across a forest-agriculture habitat ecotone in South Western Ghats, a biodiversity hotspotin India was studied.Dung baited pitfall traps were used to collect dung beetles from forest, ecotone and agriculture habitat. Community attributes such as species richness, abundance, diversity,indicator and detector species were recorded in the study sites. Species composition varied between the three habitats. Greater similarity in species composition was observed between forest and ecotone. This isattributed to the presence of heliophilic species in the region, adapted to survive in forest and the open edge. Though forest recorded higher abundance,ecotone and agriculture habitat recorded higher species richness and diversity. Low diversity in forest resulted from decreased equitability in the overall forest assemblage resulting from increased dominance of few species such as Onthophagusfurcillifer and O. pacificus. Higher species richness in ecotone and agriculture habitat was associated with heliophilicspecies that respond positively to disturbance, whereas stenotopic species adapted to closed canopy were negatively affected in the region.Onthophagusfurcillifer, the indicator species in the forest and ecotone was also the detector species in agriculture habitat. Presence of such species in the region that are adapted to survive in widely different habitat types is a result of decades of forest degradation and fragmentation in the Western Ghats which led to the establishment of heliophiles andsynanthropic species in the region.Such increase in species richness in disturbed habitat is not considered a positive attribute, as original species composition is altered to favor disturbance adapted species in the region.