Provisioned Parastrachia japonensis (Hemiptera: Cydnidae) nymphs gain access to food and protection from predators

Females of the shield bug Parastrachia japonensis Scott progressively provision nymph-containing nests with drupes of the host tree, Schoepfia jasminodora (Olicaceae: Rosidae: Santales). The majority of nests are 5-15 m from the host tree, a distance thought to have been a major impetus for the occurrence of provisioning in this species. However, the function of provisioning is not well understood. We carried out two field experiments to determine whether provisioning is nutritionally important and whether it affords protection against predation. Development of nymphs was significantly delayed and their survival was low in the absence of provisioning, even when nests were within the area of ground on to which the drupes fell, apparently because of the poor quality of the majority of the drupes. Selective provisioning of good-quality drupes by female P. japonensis, a semelparous species, was thus necessary for young nymphs to obtain enough food for their development. Furthermore, even without a female in attendance, having drupes in the nest significantly reduced early mortality in the presence of a predator. (C) 2000 The Association for the Study of Animal Behaviour.