Differentiation of food habit in tree-boring insects and its ecological and evolutional significance

主要研究结果总结如下：本项目研究了木蛀虫在其寄主树木（包括槭树）上的出现趋势、寿命和攻击模式等生物学特征。比较了岩手县、福井县、爱知县、三重县和岛根县4个采集点的特征。解剖一种木黄蜂（Xiphydria ogasawarai）的新生成虫，发现雌性具有一种充满真菌孢子的新型菌体，并在粘液库中产生粘液样分泌物（Kajimura 2000）。分离真菌，在培养基上培养。研究了栓皮栎（Quercus variabilis）和黑栎（Q.serrata）混交林中扩散前橡子的种虫区系、橡子脱落的季节模式（Fukumoto and Kajimura 1999）和橡子上昆虫的攻击模式，特别是主要物种的羽化期（Fukumoto and Kajimura 1999，日本）。利用原始方法在林内澄清了更多种类的昆虫，并讨论了不同时期橡子取食行会之间的种间竞争（Fukumoto and Kajimura 2001）。通过分析4年落入种子陷阱的橡子的内部条件，检测了橡子产量和虫害的波动模式（Fukumoto和Kajimura 2000，日本）。3 .研究了昆虫造成的胚乳损失对下胚轴和胚根存活率以及发芽成功率的影响（Fukumoto和Kajimura 2000）。在某些种类的仙甲虫中，从寄主树的壁面和甲虫成虫的菌丝中分离出真菌。将分离得到的真菌在不同的温度和湿度条件下进行培养。根据这些实验结果，建立了一种半人工饲养的饲料，并开发了一种确定其后代生长期的简单方法（Mizuno和Kajimura， 2000年，日本）。通过该方法，阐明了温度对子代生长的影响。通过人工饲养实验，从成活率和其他适合度成分的角度评估了甲虫对分离真菌的依赖程度，结果表明，与一种甲虫相关的原生ambrosia真菌是其他物种幼虫的潜在食物（Kajimura 1998）。本文对第6届欧洲昆虫学大会上所取得的有关神仙甲虫的研究成果和资料进行了总结和评述，并提出了进一步的工作建议（Kajimura 1998, in Japanese; Kajimura 2000, in Japanese）。少

The major results are summarized as follows.1. Some biological features such as emergence trend, longevity and attack pattern of wood borers, which were found in their host trees, felled bloadleaved-trees inculuding Acer spp., were examined for the project term. The features were compared among collection sites, Iwate, Fukui, Aichi, Mie and Shimane.2. Dissection of emerging adults of a xiphydriid woodwasp, Xiphydria ogasawarai, revealed that females possessed a new type of mycangia filled with fungal spores and produced a slime-like secretion in mucus reservoir (Kajimura 2000). The mycangial fungi were isolated and incubated on culture media.3. Seed-insect fauna of pre-dispersal acorns and seasonal patterns of acorn fall (Fukumoto and Kajimura 1999) and attack patterns of the insects on the acorns, in particular emergence periods of major species (Fukumoto and Kajimura 1999, in Japanese), were investigated in a mixed stand of Quercus variabilis and Q.serrata. Oviposition (boring) perio … More ds of the insects were clarified by using an original method in the stand, and interspecific competition between acorn-feeding guilds according to the periods was discussed (Fukumoto and Kajimura 2001).Fluctuation patterns of acorn production and insect infestation were detected by analysis of inner conditions in the acorns that fell into seed traps for four years (Fukumoto and Kajimura 2000, in Japanese). Rates of hypocotyl and radicle survival and of germination success were examined in relation to endosperm loss due to the insects (Fukumoto and Kajimura 2000).4. In some species of ambrosia beetles, isolations of fungi were made from walls of galleries in the host trees and mycangia of beetle adults. The isolated fungi were cultured under different conditions of temperature and humidity. Based on results of these experiments, a semi-artificial diet for rearing of the beetles was established, and a simple method for determining growth periods of their offsprings was also developed (Mizuno and Kajimura 2000, in Japanese). By the method, effects of temperature on the offspring growth were clarified. Degrees of dependence of the beetles on the isolated fungi were evaluated from view points of survival rate and other fitness compornents by artificial rearing experiments, which gave a notable result suggesting that primary ambrosia fungi associated with one beetle species are potential food for larvae of other species (Kajimura 1998). All the results and informations about ambrosia beetles, some of which were obtained in the 6th European Congress of Entomology, were summaried and reviewed, and further works were also proposed (Kajimura 1998, in Japanese ; Kajimura 2000, in Japanese). Less