Factors influencing the production of pygidial secretions in the dung roller beetle Canthon smaragdulus (Coleoptera: Scarabaeinae)

Abstract

The dung roller beetle Canthon smaragdulus (Scarabaeinae) has a pair of pygidial glands whose secretions have different functions. However, the factors influencing the production of pygidial secretions in these dung beetles are not known. This study is the first to evaluate differences in the amount of pygidial secretions produced by C. smaragdulus individuals in relation to body mass, sex and social status (mature males and females alone or in couple). We also evaluated whether the production of pygidial secretions is stable over time in individual beetles. To achieve this, we collected pygidial secretions from 120 C. smaragdulus individuals and measured their body mass and body size. Secretions were collected twice more, for a total of three samples per specimen, which were obtained every seven days. Our results suggest that alone males produce higher amounts of pygidial secretions than females alone, couple males and couple females. Only the body mass of couple males was positively correlated with the amount of pygidial secretions. This was probably due to couple males remaining in the nest for a few days. Our results confirm that the production of pygidial secretions in dung roller beetles can be influenced by body mass, sex and social status. Thus, further experiments should assess the production of pygidial secretions throughout the dung beetle life cycle under different behavioural contexts such as defence, protection of the nest and reproduction.