Maternal care behaviour and kin discrimination in the subsocial bug Tectocoris diophthalmus (Hemiptera:Scutelleridae)

Most insects employ non-caring strategies to safeguard their eggs and offspring from predation. Parental care behaviour is extremely rare in insects, but has been described in several insect groups and particularly in the Hemiptera. Given that such behaviour is considered an evolutionary precursor to more complex forms of insect sociality, investigating the dynamics of parental care may inform our understanding of social evolution. In this paper, we describe the oviposition and maternal care behaviour of the egg-guarding cotton or hibiscus harlequin bug Tectocoris diophthalmus (Thunberg, 1783) in the field. We also report the results of experimental manipulations designed to test for egg discrimination mechanisms in this species. Our observations indicate that females lay about 100 eggs in a cylindrical cluster around a branch or leaf petiole. Maternal care is limited to egg straddling and defensive postures and behaviours. These were only displayed when walking invertebrate predators approached the egg clutch; mothers were observed to react to the presence of parasitoid wasps on their clutches. Protective behaviours are only displayed by guarding females and are possibly triggered by oviposition, but will cease permanently if females are separated from their clutch for more than a few minutes. We found no evidence for clutch discrimination, as females guarded their own clutch as readily as unrelated eggs until hatching. Egg guarding in this species may have been selected to enhance offspring survival in a high predation environment.