【作者】 卜书海；

【导师】 李青旺；

【作者基本信息】 西北农林科技大学 ， 动物遗传育种与繁殖， 2011， 博士

【摘要】 华山松大小蠹(Dendroctonus armandi Tsai et Li)是秦岭巴山林区华山松的毁灭性森林害虫,严重威胁着秦岭巴山森林生态系统的稳定性。华山松大小蠹的发生规律、华山松大小蠹对寄主树木的选择性、飞行与扩散机制、华山松大小蠹和蓝变真菌的关系等已有大量研究,但华山松大小蠹消化系统结构、生殖与种群繁衍等未被充分地研究,直接制约了对华山松大小蠹种群数量波动和成灾机理的研究,以及对华山松大小蠹种群数量调控技术的研究和探索。为此,本文应用生理生化和电镜等技术,通过对华山松大小蠹成虫消化系统的形态与功能、生殖与种群繁衍的关系研究,旨在揭示华山松大小蠹种群数量波动的机制。1.对华山松大小蠹成虫前肠、中肠和后肠组织与细胞结构的研究,结果表明华山松大小蠹成虫消化道由前肠、中肠、和后肠组成,前肠分为口腔、咽、食道、嗉囊和前胃,食道和嗉囊存在着棘突,前胃具有精细的几丁质骨板结构;中肠由中肠前段、中肠后段和160个胃盲囊组成,胃盲囊位于中肠的后段,呈6纵列排列;后肠分为后肠前段和后肠后段,具有6个马氏管,后肠具有隐肾管系统,存在纵肌,但不存在细小的角质棘突。2.华山松大小蠹成虫中肠后段具有长的微绒毛、丰富的糙面内质网和多皱褶的基底内褶;同时,中肠中的围食膜是由2层不连续的套筒管状结构构成,每隔1 um呈纽扣状凸起于表面,属于Ⅱ型围食膜;后肠上皮表面具有角质层,上皮缺乏微绒毛。羽化成熟的华山松大小蠹雌性成虫中肠上皮细胞质具有发达的糙面内质网和大量高电子密度颗粒,这可能与小蠹虫中肠激素合成有关。3.对危害华山松韧皮部组织的16种小蠹虫前胃板结构研究,结果表明16种小蠹虫前胃均有8个骨板组成,每个骨板又被分为具齿的板状部和可移动的咀嚼刷和长刚毛的片状部两部分。这些韧皮小蠹虫胃板的骨化程度、板状部结构、咀嚼刷和刚毛的类型存在明显的差异,可分为A型、B型和C型3种类型,韧皮小蠹虫前胃板结构的差异不仅可以作为种的分类特征,而且前胃板结构的分化与营养的摄取有密切的关系。4.对华山松大小蠹雄性成虫生殖系统和精子发育的超微结构研究,结果表明华山松大小蠹雄性生殖系统由睾丸、输精管、储精囊、射精管、环状附腺、线形附腺(分长支和短支类型)组成。精细胞的分化发生在育精囊内,每个育精囊内精细胞可达到512个。华山松大小蠹精子和精子发生具有鞘翅目昆虫的基本特征,精子头部由3层结构的顶体和细胞核组成;尾部由线粒体衍生物、副体和9+9+2轴丝结构等细胞器组成。但华山松大小蠹精子在精细胞发育的早期,细胞核的拉伸和染色质的浓缩形成凸字形;精子超微结构中具有独特的“h”型顶体泡,以及位于精子尾部中段的海绵体结构和位于精子主段的涨泡状结构。此外,华山松大小蠹雄性具有环形和线形2种类型的附腺;每个睾丸含有20个精巢小管明显区别于鞘翅目其它昆虫。5.华山松大小蠹雌性成虫生殖系统和卵子发育的超微结构研究,结果表明华山松大小蠹雌性生殖系统由4个端滋式卵巢管(1对卵巢)、1对侧输卵管,1个中输卵管,和1个受精囊组成,缺少附腺。卵巢管原卵区为合胞体区,前卵泡细胞和停滞卵母细胞分布在基部区域;卵黄区由7~10个线性排列、处于前卵黄生成期和卵黄生成期发育阶段的卵泡组成。随着卵泡的发育,卵泡细胞间间隙增大,卵泡细胞质中出现更丰富的糙面内质网和线粒体,这些说明卵黄生成期的卵泡细胞促进了卵母细胞外源蛋白的吸收,同时也表明卵泡细胞参与卵黄膜的合成;卵母细胞质中积累了更多的脂滴,卵黄颗粒和线粒体、内质网、高尔基体等细胞器,说明卵母细胞自身参与到卵黄成分的合成过程。同心轮状糙面内质网的存在,是卵黄生成晚期卵母细胞的典型特征。更多还原

【Abstract】 The Chinese white pine beetle, Dendroctonus armandi (Coleoptera: Scolytinae) as a pioneer of bark beetles’ecosystem in Qinling Mountains, is specifically destroying Chinese white pine Pinus armandi. So it is seriously harmful to ecological stability of forestry in Qinling–bashan Mountains. The research was fully carrying out on the life history, mechanism of invading host tree, pheromone, flight and dispersal, the relation with their symbiosis and so on. However, the studying on their population fluctuation and mechanism of the Chinese white pine destroyed by D. armandi, as well as the exploration of the technical management in D. armandi will be directly limited because of failure of basic research on structure of alimentary canal and reproduction and population growth. Hence, we closely focused on the basic study on bark beetle’s digestion and reproduction to reveal the mechnism of their population fluctuation. We clarified its adaption to nicho under bast from the aspect of the morph-function of alimentary system and reproductive system by using SEM, TEM and so on. The results are as follows:1. The morphology and histology of the alimentary canal of the Chinese white pine beetle were studied by means of light and electron microscopy. The alimentary canal composed of foregut (formed by oral cavity, pharynx, esophagu, crop and proventriculus), midgut (formed by the anterior, posterior and 160 gastric ceca) and hindgut (formed by the anterior, posterior and 6 tuba Malpighii). Although many structures, such as 6 tuba Malpighii, the cryptonephridial system, spines in the esophagus and crop and chitinous plates in the proventriculus, were found to be similar to those reported for other Dendroctonus Erichson species, some differences were apparent, such as 6 row gastric ceca in the midgut, longitudinal muscle in the hindgut, fine spines on the hindgut cuticle, and specialized proventricular plates.2. The longer microvilli, abundant the rough endoplasmic reticulum (RER), and the folds of the basal labyrinth strongly existed in the epithelium of the posterior of midgut. Meanwhile, peritrophic membrane, which belonged to typeⅡ, was 2 layers tubiform with buttons-like structure every 1um in its surface. The hindguts structural characteristics, such as the cuticle in the surface of epithelium, the absence of microvilli, the scarce amount of organelles, and the thick muscle tissue, suggested that absorption and synthesis processes should be lower in this region than in the midgut. Also, more RER and redundant granules with strong electron dense were present in the epithelial cells of the midgut from the mature female individual. It indicated that Endodermal or midgut cells function as the site of pheromone synthesis.3. Proventriculi morphology was studied in 16 species of bark beetles (Coleoptera: Scolytinae) representing two subfamilies from host tree (Pinus armandi Fr.) by using light microscopy and scanning electron microscopy. General Proventricular morphology was found to be similar for those of species analyzed, with the presence of eight thick cuticular plates. Each chitinous plate can be divided in an anterior plate with sclerotized appendices formed by denticles or spines, and a masticatory plate with the movable brushes and long fine bristles. Obvious differences were observed in the sclerotization degree, the shape of the anterior plate and type of sclerotized appendices among the different bark beetles groups. Three types of proventriculus were identified according to the basic morphous comparison of the chitinous plates, and their morphology may supply auxiliary characters for taxonomy of these bark beetles. Obvious morphous variation and the sclerotization level of proventriculus may reflect an adaptation to variations in diet, which lead to occurrence of spatial and time sequence for 16 bark beetles in P. armandi.4. The reproductive tract and Spermiogenesis in Chinese white pine beetle were investigated by light and electron microscopy. The reproductive tract was composed of testes, deferent ducts, seminal vesicles, strand-shaped accessory glands, curcled accessory gland per unit and one common ejaculatory duct. The differentiation of spermatids occured within cysts of up to 512 germ line cells each one. While the spermatozoon and spermiogenesis was shown to possess several traits that are characteristics of other beetles in general. The head was formed by a three-layered acrosome with the perforatorium, the acrosomal vesicle, the extra-acrosomal layer and the nucleus. The flagellum presented a typical axoneme with a 9 + 9 + 2 microtubule pattern, two accessory bodies and two mitochondrial derivatives, which appeared with different sizes. In both derivatives there were dense crystalloid regions. Some peculiar characteristic were noted: the presence of tridents shaped nucleus in early spermatid stage, the presence of“h”shaped acrosomal visicles, a puff-like structure, the centriole derivative and a loose“large coil”-like spony body structure in sperm. Furthermore, the occurrence of 20 tubules and two type accessory glands in D. armandi differed from other Coleopteran so far examined.5. The present study described the female reproductive tract and the ultrastructure of meroistic telotrophic ovaries of the bark beetle D. armandi. The female reproductive system consisted of four ovaries and two short lateral oviducts, one oviduct and a spermatheca, devoid of the accessory glands. In this type of ovary, from apex to base individual ovarioles had four well defined regions: a terminal filament, tropharium (trophic chamber), vitellarium and pedicel (ovariolar stalk). Tropharia were not differentiated into distinct zones and consist of syncytium containing multiple trophocyte nuclei embedded in a common cytoplasm. Early previtellogenic (arrested) oocytes and prefollicular cells were located at the base of the tropharium. The vitellarium housed linearly arranged developing oocytes each of which was connected to the trophic core by a broad nutritive cord. Each oocyte was surrounded by a single layer of follicular cells. For D. armandi in the emergence phase, oocytes only in pre-vitellogenic and vitellogenic stages were observed in the vitellarium. Along with the developing of oocytes, the larger intercellular spaces, more redundant mitochondria and RER in the follicular epithelium were present than those observed in the previous stage. Our data clearly indicated that the opening of these spaces in the follicular epithelium of D. armandi oocytes increased as the intake of exogenous proteins intensifies, that was, in middle and end stages of vitellogenic oocytes. Also, the follicular epithelium participated in the synthesis of pre-vitelline membrane. Meanwhile, more yolk granules and lipid droplets with the larger sizes in the oocytes were than those observed in the previous stage. There was rich in Golgi apparatus, RER and mitochondria in the cytoplasm of oocyte, which showed the oocyte itself, participated in the synthesis of yolk. A peculiar characteristic was noted that redundant RER whorls which surrounded large characteristic lipid droplets or protein were present in the end stage of vitellogenic oocytes.更多还原