ABSTRACT

The nidification (nesting) process of the Scarabaeinae beetles exhibits a range from relatively primitive levels, similar to those seen in other subfamilies of the Scarabaeidae, to highly complex nests. It is possible to follow the successive stages of this evolution in different suprageneric groups and even among species of the same genus.

Evolved nidification in Scarabaeinae has two main forms, the adaptive values of which appear to be equivalent. In the first of these behaviors, the mother covers the food destined for the larva (the brood ball) with a thick layer of soil. Immediately after laying the egg, the mother abandons the nest. The other behavior includes postovipo – sition care by the mother, with variable participation (depending on the species) by the male. These types of subsocial care have been identified in 67 species belonging to 13 genera. These genera belong to distinct phylogenetic lines, with no relationship other than that they are all Scarabaeinae (a monophyletic group).

Subsocial care in Scarabaeinae cannot be related to a specific morphological characteristic or to a concrete physiological function common to all known cases. From an ecological perspective, subsocial care appears to be a response, according to known cases, to different selective pressures.