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本文研究了小地老虎、家蚕、直纹稻苞虫和二化螟幼虫对苏云金杆菌的患病症状及组织病变。经口摄入致死剂量细菌后,家蚕、直纹稻苞虫表现出强烈症状,4—8小时内血淋巴 pH 值上升,迅速瘫痪死亡;二化螟没有明显的外部症状,血淋巴 pH 值保持不变,2—3日死亡。小地老虎不感病,行为、血淋巴 pH 值、组织形态等均无异常表现。苏云金杆菌的三个株系对同一幼虫所引起的症状和组织病变基本相同。细菌伴孢晶体分解毒素导致幼虫中肠敏感部位细胞坏死、脱落是幼虫死亡的直接原因;中肠坏死后,细菌进入血腔引起败血症进一步破坏了虫体的其它组织、器官。
In this paper, the symptoms and histopathological changes of Bacillus thuringiensis were studied in the larvae of the small tiger, the silkworm, the rude rice and the stem borer. After oral ingestion of the lethal dose of bacteria, the silkworm and the germplasm showed a strong symptom. Within 4 to 8 hours, the pH value of the hemolymph increased rapidly and paralyzed to death. There was no obvious external symptom on the stem borer and the hemolymph pH remained Unchanged, 2-3 days of death. Small tiger is not susceptible to disease, behavior, hemolymph pH, histological abnormalities showed no abnormalities. The three strains of Bacillus thuringiensis caused by the same larvae symptoms and histological lesions are basically the same. Bacterial spore crystal break down toxins lead to necrosis of the sensitive part of the larvae midgut, shedding is the direct cause of death of larvae; necrosis of the midgut, the bacteria into the bloodstream caused by sepsis further undermine the parasites of other tissues and organs.