【摘要】 为明确微孢子虫对草地贪夜蛾[Spodoptera frugiperda （J. E. Smmith）]的生防机制，本研究采用实时荧光定量PCR（qRT-PCR）检测技术和组织病理学切片法研究草地贪夜蛾3龄幼虫感染微孢子虫后，中肠等组织微孢子虫浓度及组织病理变化情况，并以未取食微孢子虫的草地贪夜蛾幼虫为对照，分析微孢子虫对草地贪夜蛾幼虫血淋巴酶活性的影响。荧光定量结果显示，微孢子虫在侵染初期即可在中肠组织中被检测到，第4天左右扩展到肠外，第6天时中肠内的浓度达到第一个高峰，为2.05×10¹² copies·μL^-1，第9天时中肠外的微孢子虫浓度达到8.97×10¹² copies·μL^-1。石蜡切片结果显示，中肠肠壁细胞出现环肌肿大、空泡增加、细胞变形拉长、杯状细胞减少脱落、细胞解体等病变，且随侵染时间的增加，微孢子虫突破肠壁细胞向外扩展，马氏管、丝腺和脂肪体等组织也先后发生相应病变。酶活性测定结果显示，感染微孢子虫对幼虫血淋巴乙酰胆碱酯酶和谷胱甘肽S-转移酶活性有影响，具体表现为乙酰胆碱酯酶活性较对照增加，谷胱甘肽S-转移酶活性则降低；而对羧酸酯酶活性无显著影响。本研究结果为微孢子虫侵染技术的研发及其在草地贪夜蛾生物防治技术领域的应用扩展提供了理论依据。更多还原

【Abstract】 To elucidate the biocontrol mechanisms of microsporidia against Spodoptera frugiperda larvae, quantitative real-time PCR（qRT-PCR） and histopathological sectioning were utilized to investigate the concentration of microsporidia and tissue pathological changes in various tissues such as the midgut of 3rd-instar S.frugiperda larvae after being infected with microsporidia. The larvae of S. frugiperda did not ingest microsporidia was used as the control group to analyze the effect of microsporidia on the hemolymph enzymes activity in S.frugiperda larvae. The qRT-PCR results showed that microsporidia could be detected in the midgut tissue at the early stage of infection, microsporidia spread outside the midgut around on 4^th day, the concentration in midgut reached the first peak on the 6^th day, with a value of 2. 05×10¹² copies·μL^-1, and the concentration outside the midgut reached 8. 97×10¹² copies·μL^-1 on the 9^th day. The paraffin section results indicated that pathological changes such as enlargement of circular muscles, increased vacuoles, deformed and elongated cells, reduced and shed goblet cells, and cell disintegration occurred in the midgut intestinal wall cells. With the increase of infection time, the microsporidia broke through the intestinal wall cells and spread outwards, resulting in corresponding pathological changes in markov tubules, silk glands and adipoid body successively.The results of enzyme activity in S. fragiperda larvae showed that, compared with the control group, microsporidia infection impacted on the activities of acetylcholinesterase and glutathione S-transferase in the hemolymph of larvae, specifically manifested as increased acetylcholinesterase activity and decreased glutathione S-transferase activity. However, it had no significant effect on the activity of carboxylesterase. The results of this study provide a theoretical basis for the development of microsporidian infection technology and its expanded application in the field of biological control technology for S. frugiperda.更多还原