Seasonal Activity of Dung Beetles (Scarabaeinae) in a Forest in South Western Ghats

Scarabaeinae dung beetle activity is strongly influenced by rainfall seasonality. Rainfall affects the quality and quantity of dung available, affects reproductive performance and triggers emergence and activity indung beetles. Effects of rainfall seasonality oncommunity attributes of dung beetles such as abundance, species richness and diversity in a forest in South Western Ghats was studied. Dung beetles were collected using cow dung baited pitfall traps during the southwest monsoon, northeast monsoon and summer season from the forest habitat. Though abundance was highest during the heavy rainy periods of southwest monsoon season, favoring the two dominant species Onthophaguspacificus and O. furcillifer, species richness and diversity was higher during the moderate rainy periods of northeast monsoon. The heavy rains ofsouthwest monsoon season may not be favorable to some of the species, especially of the roller and dweller guild as the rains maintain the dung in a fluid state which makes dung ball rolling and dwelling a difficult task to perform.This was observed by the absence of the roller, Sisyphus araneolus and dweller Tibiodrepanussetosus during the southwest monsoon season. Favorable microclimatic conditions and availability of abundant trophic resourceduring the moderate rainy periods of northeast monsoon season in the forest led to the high species richness and diversity in that season. Keywords— Scarabaeinae, dung beetles, South Western Ghats, forest, rainfall seasonality.