Parental care and offspring survival in Copris incertus Say, a sub-social beetle

The effects of the lack of maternal care on offspring survival of the sub-social beetle Copris incertus Say (Coleoptera: Scarabaeidae: Scarabaeinae) were tested experimentally by excluding the female and determining the most vulnerable stage of development. Time budget studies were also conducted to determine the amount used by 10 females during the whole cycle from the making of the nest to the emergence of adults. A Kruskal–Wallis test and the subsequent non-parametric multiple comparisons showed a significant difference in survival between nests cared for by the mother and nests where the mother was excluded. Key-factor analysis showed that the absence of parental care affected offspring survival in the transition from the pupal to adult stage. Time budget studies indicated that, whether active or inactive, females were in direct association with the brood balls. Balls that received no care (in experimental exclusions or where the female abandoned the nest) were invaded by the fungi Metarrhizium anisoplae and Cephalosporium sp., which covered the surface and the inner part of the ball, considerably affecting pupal survivorship. Results show that sub-social care increases the probability of juveniles reaching adulthood.