EUROPEAN JOURNAL OF ENTOMOLOGY

Eur. J. Entomol. 104 (2): 341-345, 2007 | DOI: 10.14411/eje.2007.049

Period of adult activity and response to wood moisture content as major segregating factors in the coexistence of two conifer longhorn beetles, Callidiellum rufipenne and Semanotus bifasciatus (Coleoptera: Cerambycidae)

Ryûtarô IWATA, Takahisa MARO, Yasushi YONEZAWA, Tôru YAHAGI, Yoshirô FUJIKAWA^*

Department of Forest Science and Resources, College of Bioresource Sciences, Nihon University, Fujisawa 252-8510, Japan;

The cerambycid borers Callidiellum rufipenne (Motschulsky) and Semanotus bifasciatus (Motschulsky) infest coniferous logs in Japan, with the latter distributed in the north and at high altitudes, where both species occur sympatrically. Semanotus bifasciatus adults were active at low temperatures and very active after sunset, and less active but never inactive in the daytime, whereas C. rufipenne adults were usually active at high temperatures and almost only in the daytime. At an almost constant temperature, C. rufipenne adults were almost inactive at night, whereas S. bifasciatus adults showed only an obscure decline in activity in the morning. Of a horizontal log, the upper surface tended to be drier and lower surface wetter, and C. rufipenne larvae grew large if they were in the upper part of a log, whereas S. bifasciatus larvae grew large if in the lower part. Thus, the coexistence of these two species can be ascribed to two major segregation factors: adult segregation based on temperature and sunshine, and larval segregation associated with the moisture content of the wood.

Keywords: Cerambycidae, Callidiellum rufipenne, Semanotus bifasciatus, coexistence of species, resource partitioning, diel activity, wood moisture content, temperature, sunshine

Received: July 19, 2006; Revised: December 18, 2006; Accepted: December 18, 2006; Published: April 25, 2007  Show citation