1 Research Article Open Access Selection of B. thuringiensis strains containing genes effective in the control of

© 2015 Ana Rita N. Lemes et al., This is an open access article published under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Preferred citation for this article: Ana Rita N. Lemes et al., 2015, Selection of B. thuringiensis strains containing genes effective in the control of Spodoptera frugiperda., Bt Research, Vol.6, No.1, 1-8 (doi: 10.5376/bt.2015.06.0001) Abstract The bacterium Bacillus thuringiensis (Berliner) is an important entomopathogen that can replace chemical pesticides in crops. In addition to the endotoxins found in B. thuringiensis, new proteins have been studied recently, such as Vip and Chitinase, which can enhance toxic effects by acting synergistically. Thus, the objectives of this work were to select new B. thuringiensis isolates carrying cry1Fa, vip3Aa, and chi; to verify polymorphisms based on PCR-RFLP analysis; and to evaluate mortality and existence of synergistic effects of these genes on Spodoptera frugiperda larvae. A total of 114 isolates were subjected to screening via PCR to detect the vip3Aa, cry1Fa, and chi genes. Neonatal larvae of S. frugiperda were bioassayed using isolates containing one, two or all three genes and were compared to the standard strains. The PCR-RFLP analysis showed the absence of polymorphisms in these gene regions. The B. thuringiensis isolates from different regions of Brazil contained different combinations of the cry1Fa, vip3Aa, and chi genes. The presence of vip3Aa appeared to act synergistically with chi, and the combination of all three genes cause