Huang Bao-Fu, Feng Ming-Guang
Institute of Microbiology, College of Life Sciences, Zhejiang University, Hangzhou, Zhejiang 310058, People's Republic of China.
Mycopathologia. 2009 Sep;168(3):145-52. doi: 10.1007/s11046-009-9207-7. Epub 2009 Apr 24.
The tolerances of 20 Beauveria bassiana isolates derived from host insects worldwide to UV-B irradiation were assessed quantitatively in multi-dose bioassays. Conidial suspensions of the isolates smeared on glass slides were exposed to the gradient UV-B doses of 0.1-1.6 J cm(-2) (D), which generated from 0.75 to 10.17 min irradiation of weighted 312-nm wavelength at 2.0-2.61 mW cm(-2). Irradiated conidia were then incubated for 24 h at 25 degrees C under saturated humidity. The ratio of germination at each dose over that in the blank control was defined as survival index (I (s)). For all isolates, the I (s) - D observations fit well with the survival model I (s) = 1/[1 + exp(a + bD)] (0.94 < or = r (2) < or = 0.99) generated widely spanned lethal doses of 0.154-0.928, 0.240-1.139, and 0.383-1.493 J cm(-2) for their losses of 50%, 75%, and 95% viabilities, respectively. These were far below the solar UV-B dose of 2.439 J cm(-2) measured in a sunny day during the summer. The large variation of UV-B tolerance among the isolates indicates a necessity to select UV-tolerant candidates for formulations applied to insect control during summer. The highly efficient bioassay method was developed to measure accurately the UV-B tolerances of fungal biocontrol agents as lethal doses.
在多剂量生物测定中，对来自世界各地寄主昆虫的20株球孢白僵菌分离株对UV-B辐射的耐受性进行了定量评估。将涂抹在载玻片上的分离株分生孢子悬浮液暴露于0.1 - 1.6 J cm(-2)（D）的梯度UV-B剂量下，该剂量由在2.0 - 2.61 mW cm(-2)的加权312纳米波长下照射0.75至10.17分钟产生。然后将经辐照的分生孢子在25℃、饱和湿度下培养24小时。将各剂量下的萌发率与空白对照中的萌发率之比定义为存活指数（I(s)）。对于所有分离株，I(s) - D观测值与存活模型I(s) = 1/[1 + exp(a + bD)]拟合良好（0.94≤r(2)≤0.99），其50%、75%和95%活力丧失的致死剂量分别为0.154 - 0.928、0.240 - 1.139和0.383 - 1.493 J cm(-2)。这些剂量远低于夏季晴天测得的2.439 J cm(-2)的太阳UV-B剂量。分离株之间UV-B耐受性的巨大差异表明，有必要选择耐UV的候选菌株用于夏季昆虫防治制剂。开发了高效生物测定方法来准确测量真菌生物防治剂作为致死剂量的UV-B耐受性。
