Thermoregulation and Response to Competition in the African Dung Beetle Kheper nigroaeneus (Coleoptera: Scarabaeidae)

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Abstract
Previous studies have shown that some large African dung beetles maintain an elevated thoracic temperature while constructing and rolling dung balls, while others allow body temperature to decline to near ambient temperatures. These studies suggest a causal relationship between elevated thoracic temperature and intense competition for dung The ability for endogenous temperature regulation is well developed in Kheper nigroaeneus, a diurnal dung ball roller found in Kruger National Park, South Africa. We studied K. nigroaeneus on the dung of large herbivores during the rainy season. We here report that, although winners of conspecific contests for possession of already constructed dung balls have significantly higher thoracic temperatures than losers, K. nigroaeneus does not maintain an elevated body temperature while making or rolling dung balls under competition. Rather, K. nigroaeneus responds to inter- and intraspecific competition by reducing both ball construction time and ball volume prior to initiating ball rolling, thereby reducing potential loss of energetic investment. On arrival at fresh dung, beetles assessed both dung quality and intensity of competition and often rejected dung that had begun to dry or on which many conspecifics were already present. Alternative dung-handling strategies by other species (e.g, pellet sequestering and kleptoparasitism) are discussed.

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