Overwintering sites of the Japanese carrion beetle Eusilpha japonica

Abstract

Overwintering sites have recently been a focus of research into adaptive insect behavior in areas where winter is severe; however, little is known about the overwintering sites of most insects, including common ground or carrion beetles. Here, we reveal the overwintering site of Japanese carrion beetles Eusilpha japonica (Motschulsky) (Coleoptera: Silphidae). These beetles occupy various locations between spring and autumn; however, they are not observed in most of these places in winter. To investigate where they overwinter, a thorough scan was made of 109 sites. Overwintering beetles were found at 21 of 73 sites near to trees, and no beetles were observed at 36 sites that were not close to trees. To evaluate the influence of trees on the abundance of overwintering beetles, we established a quadrat consisting of 518 subquadrats in a suitable habitat with varying distances to the nearest trees. We caught 118 overwintering beetles in the quadrat. More beetles existed in subquadrats closer to trees, and analyses that considered spatial autocorrelation revealed a negative correlation between beetle frequency and distance to the nearest tree.