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苏芸金杆菌以色列变种(Bacillus thuringtensis var. tsraelensis de Barjac)对尖音库蚊(Culex pipiens var. pallens Coq uillett)三龄幼虫具有极高的毒性,在浓度为1.5×10~4芽孢/毫升时,死亡率达100％。其他几个变种B. T. var. thuringiensis(E—009)var. kurstaki(HD—1)、var. kenyae(7404)、var. ostriniae(006)浓度达4×10~5芽孢/毫升时仍未见毒效。 用液体双相与等密度离心法将以色列变种的晶体与芽孢分离,分别研究晶体(纯度达99.5％以上)、芽孢(纯度达99.5％以上)对尖音库蚊幼虫的毒性。发现使蚊幼虫致死主要是晶体LC_(50)为0.023微克/毫升,芽孢也具有毒性LC_(50)为0.86微克/毫升,晶体与芽孢混用制剂的LC_(50)为(0.014微克晶体+0.014微克芽孢)/毫升。 晶体制剂在30℃和21℃的温度条件下毒力没有变化,但芽孢制剂在21℃毒力显著下降;芽孢制剂致死幼虫,立即用相差显微镜镜检,发现肠道内有大量正在萌发的芽孢,对芽孢致死的原因进行了初步分析。
Bacillus thuringiensis var. Tsraelensis de Barjac is extremely toxic to Culex pipiens var. Pallens Coq uillett third instar larvae. At a concentration of 1.5 × 10 4 spores / ml , The mortality rate of 100%. Several other varieties of BT var. Thuringiensis (E-009) var. Kurstaki (HD-1), var. Kenyae (7404), var. Ostriniae (006) effect. The crystals and spores of Israel were separated by liquid biphasic and iso-density centrifugation. The toxicity of crystal (purity over 99.5%) and spore (purity over 99.5%) to Culex pipiens pallens larvae were studied respectively. It was found that the LC 50 of the mosquito larvae was 0.023 microg / ml and the LC 50 of the spores was 0. 86 microg / ml. The LC 50 of the mixture of crystal and spore was 0.014 microgram crystal + 0.014 microgram Spore) / ml. The virulence of the crystal preparation did not change under the conditions of 30 ℃ and 21 ℃, but the spore preparation had a significant decrease in virulence at 21 ℃. The spore preparation died of larvae and was immediately examined by phase contrast microscopy. The causes of lethal spores were analyzed preliminarily.