Parental Care and Reproductive Investment in Shield Bugs (Acanthosomatidae, Heteroptera)

Abstract

Females of the three Elasmucha species (E. grisea, E. fieberi and E. ferrugata) guard their offspring by standing over them until they are small larvae; later stage larvae are abandoned. Female size limits the area that can be defended effectively. In making a given reproductive investment, a female can choose to lay several small eggs or a few big ones. The hypotheses tested were that 1) egg size should increase with the parental care, and 2) investment in the first clutch (duration of parental care and clutch mass) should affect future reproductive investment and the probability of laying a second clutch. In a laboratory study, females of the smallest species (E. grisea) had the largest clutches with many (absolutely and relatively) small eggs, and females of this species also cared for their offspring for the longest period. E. ferrugata females had the largest eggs and the shortest time of care, and it was the only species where some females laid a second clutch after a normal care period. The reproductive investment and duration of parental care in E. fieberi was intermediate to that observed in the other two species. In contrast to the general pattern among invertebrates and other ectotherms with parental care, the species with largest eggs exhibited parental care for the shortest time. Among Elasmucha, species laying many small eggs with a long time of care may involve a partial shift from iteroparity to semelparity.