Habitat specificity in African dung beetles: the effect of soil type on dung burial by two species of ball-rolling dung beetles (Coleoptera Scarabaeidae)

Abstract

The dung burial ability of two congeneric ball-rolling dung beetles, Allogymnopleurus thalassinus Klug 1855 and Allogymnopleurus consocius Peringuey 1900 was investigated in field experiments in three different textural classes of sod at contrasting moisture levels in order to seek an explanation for their strong associations with particular soil types in the field. The success and depth of burial of dung balls was measured and was strongly associated with sod hardness. Both species were unable to bury dung in soil with a hardness greater than 2 kg/cm-2. Beetles were able to utilize both sand and clay sods for dung burial sites provided the soil was soft. Hard-setting sandy clay soils exceeded the hardness threshold except during brief periods following rain but the deep sand and self-mulching clay soils did not exceed this threshold even when dry. The restriction of each species to soft soils of a particular texture is discussed.