【作者】 崔峰；

【导师】 徐洪富；

【作者基本信息】 山东农业大学 ， 农业昆虫与害虫防治， 2002， 硕士

【摘要】 本论文通过石蜡切片法、扫描电镜技术系统研究了甜菜夜蛾胚胎发育的一般过程和特点，并从组织学和生化方面研究分析了特异性杀虫剂灭幼脲类的杀卵作用，确定胚胎对药剂的最敏感阶段，即用灭幼脲类防治甜菜夜蛾卵的最佳时期。 在25℃、相对湿度80％和日光熙14小时的条件下，甜菜夜蛾的卵期约为71小时。甜菜夜蛾的卵近扁球形，颜色有多种，卵块外密布绒毛；卵的周质分两层，卵核分裂时子核形成“彗星”状活质体向卵表面迁移，引起卵黄分布的变化，卵黄在以后的发育中逐渐形成卵黄球，内有1～2个消黄细胞；子核在卵后极区形成极细胞，经分裂后成为一团原始生殖细胞，呈“帽状”，以后分两团移至胚胎腹部侧背面，被中胚层细胞包裹，形成生殖脊：胚带形成时很长，约占卵赤道面的3／4，随后不断伸长，使胚带头、尾两端向卵黄内陷入，且头部卷曲、螺旋；原肠沟出现，胚层开始分化，外层将来形成外胚层，里层形成中胚层利内胚层；浆膜早于羊膜形成，晚于羊膜破裂，羊膜在发育中后期形成临时性体壁；成神经细胞出现较早，神经系统发育、成熟得快，腹神经索早梯状，原脑分为前脑和中脑，后脑由上颚前节神经节发育而成，口道神经系出现额神经节和嗦囊神经节两大细胞群，6对侧单眼来自靠近视叶的外胚层细胞；胚胎发育到50小时左右，体壁真皮细胞开始分泌含几丁质的表皮，幼虫孵化前，其体表面布满脊突和刚毛；前肠、后肠分别来自外胚层内陷而成的原口陷和原肚陷，前肠分化为食道、嗦囊和前胃，后肠分化为前后肠和直肠，中肠来自中肠前基和中肠后基两群内胚层细胞；6条马氏管的末端插入直肠后端的肠壁内，形成“隐肾”；呼吸系统由中、后胸及1～8腹节外胚层内陷而成，到发育后期，中胸气门移至前胸，后胸气门退化：绛色细胞由胚体1～8腹节的外胚层部分细胞发育而成；体腔囊出现后，中胚层分为体壁中胚层和脏壁中胚层，体壁中胚层将来形成体壁肌、脂肪体等，脏壁中胚层形成消化道外的肌肉层，居间中胚层发育成血细胞；体壁中胚层与脏壁中胚层交界处的细胞发育成成心细胞，随着背合的完成形成心脏，并与头部伸出的大动脉相接，形成背血管；胚动分为四个阶段：胚带伸长与螺旋卷曲阶段、胚体缩短与解螺旋阶段、胚体翻转阶段、胚胎再伸长与再螺旋阶段；背合与胚体翻转几乎同时发生，背合从前、后两端向中央进行，胚体翻转结束时背合也同时完毕；孵化前，胚胎取食卵内未包入中肠的卵黄；根据甜菜夜蛾胚胎外形的发育特点，可将整个发育期分为5个阶段，即早期发育阶段、胚带伸长阶段、胚胎缩短阶段、胚胎翻转及背合阶段、胚胎再伸长成熟阶段。 甜菜夜蛾卵对灭幼脲类药剂敏感时期的试验结果表明，胚胎发育50小时左右的卵对灭幼脲类约剂最敏感，此时止是胚胎体壁真皮细胞开始分泌表皮、几丁质合成的时期。通过扫描电镜观察发现，灭幼脲类能够使甜菜夜蛾胚胎表皮局部出现破裂，呈孔洞状，体壁上的脊突萎缩，从而导致胚胎死亡。通过生化方法测定几丁质分解酶活性，发现用灭幼脲处理发育到一定阶段的卵较正常发育的卵几丁质分解酶的活性升高，说明灭幼脲类药剂能在一定程度和一定时间内增强几丁质分解酶的活性或诱导几丁质分解酶产生活性。幼虫孵化前死亡有可能与用药后几丁质分解酶活性提高 崔峰：酣菜夜蛾胚胎发育的研究有关，即胚胎皮细胞分泌的儿厂质被灭幼腺诱导激活的儿］质分解酶所分解，或几厂质的合成受到分解酶的抑制，因而导致胚胎无法形成IL常的表皮。作者对此作出一大胆的猜测，还有待I运川分f生物学和其他生化手段加以论址。更多还原

【Abstract】 The course and characters of the embryonic development of beet armyworm, Spodoptera exigua HUbner, were studied with paraffin sections and scanning electron microscopy in this paper. The ovicidal function of diflubenzuron, a kind of specific pesticide, was researched and discussed by the way of histology and biochemistry, anil the most sensitive phase to diflubenzuron for the beet armyworm embryo was also found, which meaned the best opportunity of applying diflubenzuron to kill eggs of the beet armyworm was known.The embryo period of beet armyworms was about 71 hours under the condition of 25 "C, 80%RH, 14 hours lighting per day. The egg was suboblate, multicolor and covered with villi. The periplasm of eggs included two layers. Daughter nuclei moved towards the egg surface in the form of cometic energids, which changed the spread of yolk. The yolk would become yolk sphere later which contained one or two vitellophages. Daughter nuclei in the posterior pole of eggs became cap-shaped primordial germ cells after cleavage, moved in two masses to the laterodorsal abdomen of embryo, and then were enveloped by mesoderm to form germinal ridge. The germ band was so long at the beginning as to be about 3/4 of the egg equator perimeter, and then became longer and longer so that the head and cauda were immersed into yolk, as well as the head curling and twisting. The germ band started to be delaminated into two layers with the appearance of gastral groove. The outer layer would become ectoderm and the inner would form mesoderm and endoderm. Serosa formed earlier and broke later than amnion, the latter forming temporary body wall in the later development. Neuroblasts appeared early and the nervous system developed very quickly. The ventral nerve cord looked like a ladder. Protocerebrum would developed into procerebrum and deutocerebrum, while tritocerebrum came from premandibular ganglion. The stomodaeal nervous system comprised frontal ganglion and ingluvial ganglion. Six pairs of lateral ocelli came out of ectodermal cells near lobus opticus. Hypodermal cells began to secrete chitinous epidermis at 50th hour around. The embryo body was covered densely with crests and chaetae before hatching. The foregut and hindgut derived respectively from the stomodaeum and proctodaeum. The foregut would be differentiated into oesophagus, crop and proventriculus while the hindgut would be composed of ileocolon and rectum. Themidgut came from anterior mesenteron rudiments and posterior mesenteron rudiments.Six Malpighian tubes formed crytonephridiel by putting their tube ends into the rectum wall. The ectodermal cells of mesothorax, metathorax and 1 to 8 abdomen got in to form the respiratory system. The spiracles at mesothorax moved to prothorax and spiracles at metathorax disappeared in the later development. Oenocytes derived from ectodermal cells of 1 to 8 abdomen. The mesoderm differentiated into somatic mesoderm and splanchnic mesoderm after coelomic sals appeared, the former developing into musculus parietalis, fat body etc., and the latter forming muscles of the alimentary canal. The median mesoderm turned into haemocytes. Cardioblasts came out of cells between somatic and splanchnic mesoderm, then formed heart after dorsal enclosure and connected with the large artery to form the dorsal vessal. The blastokinesis included four phases: germ band elongating and twisting; embryo shortening and unwinding; embryo reversing; embryo elongating and twisting again. Dorsal enclosure took place from head and cauda to center nearly at the same time of embryo reversing. The embryo ate up yolk unenveloped into the midgut before hatching. According to the characters of embryo shape, die whole embryonic development of the beet armyworm could be divided into five phases: the phase of early developing, germ band elongating, embryo shortening, embryo reversing and dorsal enclosure, embryo elongating again and maturing.Through the experiments of determining the sensitive phase of beet armyworm eggs to diflubenzuron, the outcome showed t更多还原