Kleptoparasitism and the Effect of Nest Location in a Subsocial Shield Bug Parastrachia japonensis (Hemiptera: Parastrachiidae)

Females of the subsocial shield bug Parastrachia japonensis Scott progressively provision nymph-containing nests with drupes of the single host tree Schoepfia jasminodora Sieb. et Zull. The resource is unreliable and typically poor, and females invest considerable time in searching for suitable drupes. Earlier observations have indicated that although some females nest under the host tree, most prefer to nest far from the food source, despite the difficulty involved in transporting drupes to a distant nest. Because we have observed females stealing drupes from other females’ nests, we considered that kleptoparasitism might be a factor in determining nest site preference. A manipulated field study was carried out to clarify the prevalence of kleptoparasitism in nests close to and far from the host tree and to determine how these factors affect nest success. Surprisingly, in the year of this study, when drupes were particularly scarce, more drupes were stolen, but females still collected significantly more drupes and had greater nest success, in nests located under the host tree than in those that were 5 m away. The ecological factors relevant to kleptoparasitism and nest site choice are discussed.