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

为明确三种木蜂的资源利用格局和繁殖策略，对其生物学特性和生态学特性进行了研究。产卵活动受寄主树种条件的影响较大：采伐树木后0~3d内的新鲜原木和25d以上的老原木产卵比例明显低于中原木(4~24d)。不含共生真菌的木蜂X.spectra也只对人工接种了与其他木蜂共生的粉纹夜蛾或毛果扁豆的新鲜原木表现出产卵活性。日本斑潜蝇在日本柳杉和钝顶斑潜蝇商品林中具有暴发的潜在风险，在7月左右出现高峰，并在砍伐树木后1个月内对原木有产卵偏好。在日本落叶松和日本红松树上研究了蓝斑真菌与iPS cembrae的关系。从虫体表面分离到蓝斑菌Ophiostoma Piceae和Lepitgraph sp.，表明该种甲虫是这些真菌的传播媒介。从成虫和画廊中分离到的云杉褐飞虱出现频率较高，这也表明该真菌可能是侵染日本落叶松甲虫的主要蓝斑真菌。接种试验表明，在胁迫条件下，赤松幼树受到真菌侵染的伤害较大，病斑较大，木质部水压势降低，死亡率较高。

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.