Lacoursière J O, Charpentier G
Département de Chimie-Biologie, Université du Québec à Trois-Rivières, Canada.
J Am Mosq Control Assoc. 1988 Mar;4(1):64-72.
An experimental formulation of Bacillus thuringiensis var. israelensis was used in the laboratory to assess the influence of water temperature and pH on the relationship between concentration, duration of exposure, and mortality of the northern black fly species Simulium decorum and Prosimulium mixtum/fuscum group. Mortality increases in both species with increases in duration of exposure, concentration, temperature and pH. Onset of death is shortened by increase in concentration and temperature. As temperature rises, the concentration of B.t.i. required to induce mortality decreases; the sharpest decline occurring between 12 and 18 degrees C for S. decorum, and between 4 and 8 degrees C for P. mixtum/fuscum larvae. Lower pH induces a loss of efficacy of the B.t.i. formulation on S. decorum larvae at 4 and 12 degrees C. Dialysis of the B.t.i. formulation at pH 11 for 2 h increases its potency against S. decorum larvae, suggesting an effect of an extralarval alkaline hydrolysis on the B.t.i. efficacy. An alkaline prehydrolysis of the paracrystalline bodies could therefore be used in cold and acidic environments to compensate for loss of efficacy.
在实验室中使用苏云金芽孢杆菌以色列变种的一种实验制剂，以评估水温及pH值对北方黑蝇物种——装饰蚋和混合原蚋/深色原蚋组的浓度、暴露持续时间与死亡率之间关系的影响。两种物种的死亡率均随着暴露持续时间、浓度、温度和pH值的增加而上升。浓度和温度的升高会缩短死亡开始的时间。随着温度升高，诱导死亡所需的苏云金芽孢杆菌以色列变种浓度降低；对于装饰蚋，在12至18摄氏度之间下降最为明显，而对于混合原蚋/深色原蚋幼虫，在4至8摄氏度之间下降最为明显。较低的pH值会导致苏云金芽孢杆菌以色列变种制剂在4摄氏度和12摄氏度时对装饰蚋幼虫失去效力。将苏云金芽孢杆菌以色列变种制剂在pH值11的条件下透析2小时，可提高其对装饰蚋幼虫的效力，这表明幼虫体外碱性水解对苏云金芽孢杆菌以色列变种的效力有影响。因此，在寒冷和酸性环境中，对伴晶进行碱性预水解可用于弥补效力损失。
