Emerging properties of adult woodwasps resulting from thinning-to-waste operations –A case study of Kami City, Kochi Prefecture–

Abstract

The density of woodwasps in bucked and non-bucked stems was investigated for Sugi cedar (Cryptomeria japonica). The trees were thinned in March and April, 2006 and their stems were either left full length (non-bucked), or bucked to 2 m, and were left until December 2006 so that they could be oviposited by woodwasps. The stems, 6 m from the butt end, were then placed in a netted room. The moisture content of the sapwood, and the number of emerged adult woodwasps and oviposition holes were investigated. As a result, three species of adult woodwasps was emerged. The number of adult Urocerus japonicus that emerged from bucked stems was lower than the number that emerged from full-length stems. Furthermore, the sapwood moisture content of the bucked stems in December 2006 was higher than that of the full-length stems. Additionally, there were significantly fewer oviposition holes in stems felled in April, which had high moisture content, than in stems that were felled in March.