Behavioural repertoire and the effect of male removal in a geotrupid beetle with parental care

Abstract

Although biparental care is thought to be rare among insects, it has evolved independently numerous times resulting in diverse forms and varying levels of parental involvement. Several theoretical studies address potential factors promoting biparental care in beetles; however, empirical studies target principally only species of Scarabaeidae and Silphidae families. Here, we investigated the behavioural repertoire of the breeding pairs in two natural populations of a geotrupid beetle Lethrus apterus with parental care. Changes in female care as a response to the male's absence were also investigated by experimentally removing males from pairs. We found that males spend the majority of their time at the nest entrance, while females leave their nest and collect leaves at a significantly higher rate than males. We also showed that males often desert their nests and were usually replaced by new males in a short time. The desertion of males, however, does not seem to influence females' behaviour. These findings indicate that L. apterus may have a dynamic mating system with typically short-term mate fidelity. Furthermore, our results have advanced our understanding of parental roles and nesting behaviour and contributed to the description of the distinct roles of parents in different phases of nesting events in L. apterus beetles.