Aggregation mechanisms influencing spatial distributions of dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae and Aphodiinae)

Spatial distributions of insects associated with patchy habitats such as dung, carrion, mushrooms, and fallen fruit exhibit population densities that are aggregated across patches i.e. high degree of variance. What mechanisms are used to facilitate such distributional patterns? We examined the spatial distribution of dung beetles across ten dung-baited pitfall traps over 18 months. Standardized baits were wrapped in cheesecloth to prevent beetles from having direct contact with the bait. Since beetles were trapped upon arrival, patterns of trapping were indicative of immigration processes. Eight species of dung beetles were investigated and expressed strong intraspecific aggregation (high variance) in their distributions across traps. Interspecific aggregations were present but typically of lesser magnitudes than intraspecific aggregation and indicated species-specific distributional patterns across traps. Interspecific associations were not correlated with phylogenetic relationships and functional groups. Aggregation mechanisms will be discussed.