Ecological Study of Beetles Inhabiting Cryptoporus volvatus (PECK) SHEAR (II) : Relationship between Development of the Basidiocarps and Life Cycles of Five Major Species of Beetle Inhabiting the Fungus, with Discussion of the Spore Dispersal

The relationship between the development of basidiocarps of Cryptoporus volvatus and the life cycles of five major species of beetle inhabiting the fungus was surveyed in 1992 by sampling and rearing in secondary forests composed mainly of Pinus densiflora in Seki City, Gifu Prefecture, Japan. The developmental process of the basidiocarps was divided into four stages : (1) growing stage, (2) mature stage, (3) early decay stage, (4) late decay stage. C. volvatus basidiocarps in the growing stage were found from February to early July in the study area. Overwintering adults of Cryptophagus erormis that feed only on C. volvatus flew to the basidiocarps in the growing stage in February and March, and bred on them in early April. C. volvatus basidiocarps in the mature stage were found from mid-April to late July. Overwintering adults of Aphenolia pseudosoronia, Parabolitophagus felix and Ischnodactylus loripes that feed only on C. volvatus came flying to the mature basidiocarps and bred within the volval chambers. C. erormis and A. pseudosoronia grew quickly and adults of the first generation came flying to the matured basidiocarps from late May to July. Overwintering adults of the predator Trogossita japonica flew to the basidiocarps in the mature stage from April to August. The present observations showed that immigration of the adults of these beetles was synchronized with the sporulation of C. volvatus. This suggests that C. volvatus spores adhere to the surface of these beetles and are dispersed mainly by their migration.