Provisioning call by mothers of a subsocial shield bug



Lisa Filippi, Department of Biology, Hofstra University, Hempstead, NY 11549, USA. Tel: +1 516 463 5831



The offspring of many animal species solicit food from parents using begging signals, while parents manipulate offspring behavior to optimize fitness using various signals. Female Parastrachia japonensis (Heteroptera) provision nests with drupes of the host tree. Provisioning females were recently heard emitting a low-pitched fluttering sound that we characterized in the field using a contact microphone. A single calling event consisted of multiple sound bouts of varying lengths. A fast Fourier transform analysis revealed a frequency range of 0∼1 kHz. We hypothesized that the call is specific to provisioning behavior in the context of parent–offspring communication, and tentatively designated it ‘provisioning call’. To test this hypothesis, we observed nesting females in the laboratory to determine if and when they emitted the call, and the response of nymphs. In every case, the call was clearly coordinated with female provisioning behaviors: females emitted the call only upon returning to their nests with a drupe. Moreover, nymphs quickly gathered to the drupe while the female was calling. Because nymphs usually hide in crevices throughout the nest debris while the mother is foraging, we also hypothesized that the provisioning call functions to induce nymphs to gather and feed synchronously on newly provisioned drupes. A playback experiment indicated that significantly more nymphs gathered on a drupe with the playback call than without the call, supporting this hypothesis. Furthermore, observations through nymphal development revealed that the total length of all sound bouts in a single provisioning call was shorter for females with older nymphs. This is consistent with the assumption that older nymphs should gather on the provisioned drupe more quickly than young, less-motile nymphs. To the best of our knowledge, this is the first report of a parent producing sound and/or vibration signals directly to offspring at repeated progressive provisioning events in a subsocial insect.