苏云金芽孢杆菌(Bacillus thuringiensis)感染菜青虫(Pieris rapae)幼虫的组织病理研究

本文从大体观察、显微观察和超微结构等方面对感染苏云金芽孢杆菌后的菜青虫幼虫进行了组织病理学研究。菜青虫在摄入苏云金芽孢杆菌后立即停食,30分钟后就在中肠上皮细胞中发现线粒体的脊内空间扩大、粗面内质网局部膨胀,微绒毛开始膨大并部分溶解。感染后1—2小时可见中肠上皮细胞靠近微绒毛一方出现较大的空泡,线粒体的空间进一步扩大,内质网的网膜慢慢分离。到第4小时,中肠上皮细胞的病变加剧,显微镜下看到细胞开始解体,电镜观察到线粒体开始破裂,内质网膜糊断裂。以后细胞迅速解体,到第8小时仅存基底膜,但其它组织基本完整。第10小时以后,观察到基底膜开始破裂,细菌进人血腔.脂肪体肌肉等组织均遭破坏,此时幼虫中部渐渐变黑,下痢并开始死亡。

THE HISTOPATHOLOGICAL STUDIES OF THE LARVAE OF PIERIS RAPAE INFECTED WITH BACILLUS THURINGIENSIS

Bacillus thuringiensis var. kurstaki, when administered to the Pieris raqae larvae, caused histo-and cytopathological changes, which were observed with naked eye, light microscope and electronic microscopa. Once the larvae ingested B. t. var. kurstaki, they stopped eating. By 30 min after ingestion, the microvilli of midgut epithial cells became swollen in diameter and partly disintegrated; the intracristal space of the mitochondria were irregularly enlarged; the endoplasmic reticulum were swollen locally. Within 1-2 hrs, the intracristal spaces continued to enlarge like vacuoles; the bourdary-lines of endoplasmic reticula were broken and scattered. Up to 4 hrs after ingestion, these organelles underwent disintegration, and the cytoplasm began liquefaction. About 8 hrs after ingestion, the cells sloughed off into the lumen and thus the basement membrane was exposed. Eventually, about 10 hrs to 1 day after ingestion, the basement membrane was broken and the other tissues in hemocoel, such as fat body, hypodermis, and muscles, were destroyed; then the larvae die from bacteraemia.