Selection of strains from Bacillus thuringiensis genes containing effective in the control of Spodoptera frugiperda.
Ana Rita Nunes Lemes
Suzana C. Marucci
Juliana R. V. Costa
Eliane C. C. Alves
Odair A. Fernandes
Manoel Victor F. Lemos
Janete A. DesidÃ©rio
Univ Estadual Paulista, Faculdade de CiÃªncias AgrÃ¡rias e VeterinÃ¡rias, 14884-900, Jaboticabal, SÃ£o Paulo, Brazil
Bt Research, 2015, Vol. 6, No. 1 doi: 10.5376/bt.2015.06.0001
Received: 24 Oct., 2014 Accepted: 29 Jan., 2015 Published: 31 Jan., 2015
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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 caused increased mortality in S. frugiperda larvae. Due to their insecticidal potential, these isolates are a prospective source of genes that can be used to genetically modify crops to increase the efficacy of pest control.
Biological control; Vip3Aa; Cry1Fa; chitinase