The farmer interest in biological control-based management practices using entomopathogenic fungi (EPF) for the control of many economically important insects has increased. In this process, selection of effective strains of EPF is an important criterion to control the target insect pests in efficient manner. In this context, this research work was formulated to find out environmentally effective strains of EPF in the soils of costal districts of Andhra Pradesh, India. Out of 135 soil samples collected, 9 yielded 9 strains of Lecanicillium lecanii. Among all 9 L. lecanii isolates, the least median lethal concentration (LC50) for 3rd instar larvae of the tobacco caterpillar, Spodoptera litura (Fabricius) (Lepidoptera: Noctuidae), was 1.17 × 106 spores ml−1 in L-8, followed by 1.27 × 106 spores ml−1 in L-5 in an increasing order. Likewise, the median lethal time (LT50) values of different isolates of EPF against the 3rd instar of S. litura were calculated for the uniform highest concentration of 1 × 108 spores ml−1. Among all 9 L. lecanii isolates, the lowest median lethal time (LT50) was observed as 7.70 days by L-8, followed by 7.77 days by L-5 and 8.50 days by L-7.

中文翻译：

---

分离作为生物防治剂的白晕真菌本地菌株，以对抗烟草毛毛虫斜纹夜蛾（Fabodius）的三龄幼虫（鳞翅目：夜蛾科）

农民对使用昆虫病原真菌（EPF）控制许多具有经济意义的昆虫的生物控制管理方法的兴趣有所增加。在此过程中，选择有效的EPF菌株是有效控制目标害虫的重要标准。在这种背景下，这项研究工作的制定是为了寻找印度安得拉邦沿海地区土壤中对环境有效的EPF菌株。在收集的135个土壤样品中，有9个产生了9个Lecanicillium lecanii菌株。在所有9种Lecancan L. lecanii分离物中，烟草毛虫三龄幼虫Spodoptera litura（Fabricius）（鳞翅目：夜蛾科）的最低中位致死浓度（LC50）为L-8中的1.17×106孢子ml-1，其次是在L-5中按1.27×106孢子ml-1的顺序递增。同样 对于均匀最高浓度的1×108孢子ml-1，计算了不同的EPF分离株对斜纹夜蛾3龄的致死时间（LT50）值。在所有9个Lecanii分离株中，L-8观察到最低中值致死时间（LT50）为7.70天，L-5观察到为7.77天，L-7观察为8.50天。