Damage of Ubame Oak, Quercus phillyraeoides by Oak Ambrosia Beetles, Platypus quercivorus in Muroto City, Kochi Prefecture

Abstract

The production of Tosa bincho charcoal in Kochi Prefecture is increasing in recent years. The major material of the charcoal is ubame oak, Quercus phillyraeoides that are often attacked by oak ambrosia beetle, Platypus quercivorus. In order to estimate the resource and to establish sustainable resource management system of the oak, it is necessary to understand the attack pattern of the beetle. Therefore, we surveyed the damage of the oak caused by attacking of the beetle in Muroto City, Kochi Prefecture, where is the main production area of the charcoal. A total of 560 ubame trees inhabited in 11 survey plots, of which 179 trees got damaged, but none of completely dead trees with typical symptoms of Japanese oak wilt was found. Logistic regression analysis showed negative correlation between damage ratio and tree species mixture ratio of survey plots, as well as positive correlation between damaged ratio and diameter of the tree.