Crop Protection Section, ICAR-Indian Institute of Oilseeds Research, Rajendranagar, Hyderabad, 500 030, Telangana, India.
Crop Production Section, ICAR-Indian Institute of Oilseeds Research, Rajendranagar, Hyderabad, 500 030, Telangana, India.
World J Microbiol Biotechnol. 2020 May 15;36(5):78. doi: 10.1007/s11274-020-02849-8.
Bacillus thuringiensis (Bt) and entomopathogenic fungi (EPF) are in use for management of insect pests. Continuous use of Bt can lead to problem of resistance development in insect pests. Hence use of combination formulations (CF) of microbials with diverse modes of action has been attempted to slow down the process of resistance development. Suspension concentrate (SC) formulations of a local strain of Bt var. kurstaki DOR Bt-127 were developed singly and in combination with conidia of the EPF Nomuraea rileyi (Nr) and Beauveria bassiana (Bb). Electron microscopy of Bt + Bb CF treated larvae of Helicoverpa armigera revealed simultaneous infection by both microbials indicating their compatibility. Endotoxin contents in Bt-SC, Bt + Bb and Bt + Nr CFs were 5.0, 4.7 and 4.7%, respectively. These formulations were effective against larvae of Spodoptera litura, H. armigera and Achaea janata coupled with a lowering of the effective requirement of Bt and EPF. In multi-location field trials, Bt-SC and Bt + Nr CF were highly effective against S. litura and A. janata on castor as well as H. armigera and Thysanoplusia orichalcea on sunflower. However, Bt + Bb CF was highly effective only on sunflower against H. armigera and T. orichalcea. All formulations had 24 months shelf-life at room temperature. DOR Bt-127 based SC formulations developed singly and in combination with Nr and Bb were effective against major lepidopteran pests of castor and sunflower and did not lose viability under storage at room temperature. The CFs of Bt with EPF could prove promising for mitigating resistance development to Bt.
苏云金芽孢杆菌（Bt）和昆虫病原真菌（EPF）被用于防治害虫。Bt 的连续使用可能导致害虫产生抗药性问题。因此，尝试使用具有不同作用方式的微生物组合配方（CF）来减缓抗药性发展的过程。单独和与昆虫病原真菌球孢白僵菌（Nr）和金龟子绿僵菌（Bb）的分生孢子联合开发了一种当地的苏云金芽孢杆菌变种 kurstaki DOR Bt-127 的悬浮浓缩（SC）配方。Bt+Bb CF 处理的棉铃虫幼虫的电子显微镜显示，两种微生物同时感染，表明它们具有兼容性。Bt-SC、Bt+Bb 和 Bt+Nr CF 中的内毒素含量分别为 5.0%、4.7%和 4.7%。这些配方对斜纹夜蛾、棉铃虫和 Achaea janata 的幼虫有效，同时降低了 Bt 和 EPF 的有效需求。在多点田间试验中，Bt-SC 和 Bt+Nr CF 对蓖麻上的斜纹夜蛾和 A. janata 以及向日葵上的棉铃虫和烟粉虱具有高度有效性。然而，Bt+Bb CF 仅对向日葵上的棉铃虫和 T. orichalcea 高度有效。所有配方在室温下的货架期均为 24 个月。单独和与 Nr 和 Bb 联合开发的基于 DOR Bt-127 的 SC 配方对蓖麻和向日葵上的主要鳞翅目害虫有效，在室温下储存时不会失去活力。Bt 与 EPF 的 CF 可能有希望减轻对 Bt 的抗药性发展。
