Cooperative associations of wood boring insects with micro-organisms and nematodes in forests.

通过对日本木蜂Sirex nitobei、日本木蜂Urocerus nitobei和日本木蜂Xeris spectrum的生物学和生态学特性的研究，阐明了它们的资源利用和繁殖策略。在不同的寄主树上产卵的比例不同，在采伐后0- 3d内的新鲜原木上产卵的比例和在采伐后25 d以上的老原木上产卵的比例明显低于在4- 24 d的中熟原木上产卵的比例。无共生真菌的木蜂X.spectrum也仅在人工接种与其他木蜂共生的方孔直孔菌（Amylostereumareokatum）或夏氏直孔菌（A.chailletii）的新鲜原木上产卵。在日本柳杉和钝头山核桃人工林中有发生的潜在风险，其羽化高峰期在7月左右，产卵偏好在采伐后1个月内的原木上。研究了日本落叶松和日本赤松中蓝变真菌与黑胫病的关系。蓝变真菌，云杉Ophiostoma piceae和Lepitographium sp.，从身体表面分离，这表明这种甲虫是这些真菌的载体。从日本落叶松成虫和廊道中分离到的云杉褐变菌的频率较高，表明该菌可能是感染日本落叶松甲虫的主要蓝变菌。通过对一种蓝变真菌Ceratocystis（Ophiostoma）piceae对红松幼树的致病性测定，结果表明，在胁迫条件下，该真菌对红松幼树的危害性较大，其坏死灶较大，木质部的水压势降低，死亡率也较高。

Biological and ecological traits of three woodwasp species, Sirex nitobei, Urocerus japonicus and Xeris spectrum, were investigated to clarify their pattens of resource utilization and reproductive strategies. The oviposition activity of Sirex nitobei was affected greatly by the host tree conditions : the proportions of oviposition on the fresh logs within 0-3 days and the old ones over 25 days after tree felling were much lower than those on the medium (4-24days) logs. X.spectrum, which has no symbiotic fungi with its body, also exhibited the oviposition activities only for the fresh logs inoculated artificially with Amylostereum areokatum or A.chailletii which were associated symbiotically with other woodwasp species. Urocerus japonicus, with a potential risk of outbreak in commercial plantations of Crytomeria japonica and Chamaecyparis obtusa, exhibited its peak emergence around July and ovipositional preference for the logs within one month after tree felling. The association between blue stain fungi and Ips cembrae was examined in Japanese larch and Japanese red pine trees. The blue stain fungi, Ophiostoma piceae and Lepitographium sp., were isolated from the body surface, which suggests that this beetle species was a vector of these fungi. The fact that O.piceae was consistently isolated with high frequency from both adults and galleries also suggested that this fungus species would be the principal blue stain fungus infecting the beetle attacked trees of Japanese larch. An inoculation experiment testing the pathogenicity of a blue stain fungus, Ceratocystis (Ophiostoma) piceae, to young Japanese red pine trees showed that under stressed conditions, the Japanese red pine trees were greatly damaged by the fungal invasion, with larger necrotic lesions, more reduced water pressure potential of the xylem and higher mortality than uninfested ones.