Description of the basic features of parent-offspring stomodeal trophallaxis in the subsocial wood-feeding cockroach Salganea esakii (Dictyoptera, Blaberidae, Panesthiinae)

In subsocial xylophagous cockroaches it is thought that parental feeding is important for the survival and growth of the altricial offspring, but the details of parental feeding in these groups are poorly known. We observed stomodeal (oral) trophallaxis between parents and the 2nd or 3rd instars of the wood-feeding cockroach Salganea esakii Roth, and here report basic features of trophallaxis in young families. Both the female and male parents fed young nymphs with stomodeal food, and there was no difference in the frequency of the behavior between parental sexes. Up to three nymphs could be fed simultaneously during a single trophallactic event. Adults occasionally rejected contact with nymphs by blocking them with their forelegs. Nymphs utilized trophallactic food from parents more frequently than feeding independently on wood pieces or fecal pellets. Trophallaxis between sibling nymphs was never observed. These results suggest that the 2nd and 3rd instar nymphs rely on the stomodeal substances provided by their parents, and that provisioning is an essential component of subsocial behavior in biparental wood-feeding cockroaches.