The Life History of the Japanese Carrion Beetle Ptomascopus Morio and the Origins of Parental Care in Nicrophorus (Coleoptera, Silphidae, Nicrophorini)

The subject of the origin and evolution of sociality in insects has a rapidly growing literature. Most of this pertains to the Hymenoptera. Within the Coleoptera, presocial or subsocial parental care and division of labor are known in at least nine families (Wilson, 1971). The most advanced form of parental care known in beetles is that of the Nierophorus carrion or burying beetles (tribe Nicrophorini). This generalization is based on the study of six European species by Pukowski (1933, 1934) which has since been abstracted and popularized by many (e.g., Balduf, 1935; Milne and Milne, 1944, 1976; Wilson, 1971, 1975). Briefly, a male and female form a conspecific pair at a carcass of a mouse or other small vertebrate. They work cooperatively to exclude competitors, to bury the carcass, and to shape it into a ball in a crypt. The male leaves after oviposition but the female tends the developing larvae, calling them to the carrion by stridulation, and repeatedly feeds them by regurgitation. Such behaviors do not exist in the other tribe of silphid carrion beetles, the Silphini. The only work on the life cycle of a North American Nicrophorus is a short note by Leech (1934) on N. defodiens (under the name N. conversator). Thus, it is not really known how general or widespread is the phenomenon of parental care in the genus, nor if all species are equally advanced behaviorally. There are about 20 species in the New World, and at least 65 species in all the world, in several lineages within the genus. As part of a series of studies on the comparative biology and evolution of silphid beetles, I undertook a study of the life history of Ptomascopus morio Kraatz of Japan, to learn something of the