Mortality of Oryzophagus oryzae (Costa Lima, 1936) (Coleoptera: Curculionidae) and Spodoptera frugiperda (J E Smith, 1797) (Lepidoptera: Noctuidae) Larvae Exposed to Bacillus thuringiensis and Extracts of Melia azedarach

• Published in: Brazilian archives of biology and technology Vol. 55; no. 5; pp. 725 - 731
• Main Authors: Berlitz, Diouneia Lisiane, Azambuja, Aline Oliboni de, Sebben, Alessandra, Oliveira, Jaime Vargas de, Fiuza, Lidia Mariana
• Format: Journal Article
• Language: English
• Published: Instituto de Tecnologia do Paraná (Tecpar) 01.10.2012
• Subjects: Alternative pest control; Bacillus thuringiensis; botanical insecticidal; Coleoptera; Curculionidae; entomopathogenic bacteria; insecticidal activity; Lepidoptera; Melia azedarach; Noctuidae; Spodoptera frugiperda
• ISSN: 1516-8913; 1516-8913; 1678-4324
• DOI: 10.1590/S1516-89132012000500012

Oryzophagus oryzae (Costa Lima 1936) (Coleoptera: Curculionidae) and Spodoptera frugiperda (J E Smith, 1797) (Lepidoptera: Noctuidae) cause important crop losses in southern Brazil. Control is possible by the use of the bacteria Bacillus thuringiensis and extracts of Melia azedarach. This study aimed to evaluate the mortality, in vivo, of O. oryzae and S. frugiperda submitted to two isolates of B. thuringiensis and the aqueous extract of M. azedarach. The LC sub(50) for O. oryzae due to bacteria was 5.40 mu g/mL (Bt 2014-2) and due to plant extract 0.90 mu g/mL. For S. frugiperda, the Bt 1958-2 bacterial suspension (1.10 super(10)UFC/mL) caused a 100% of corrected mortality, showing that the purified Cry proteins caused a CL sub(10) of 268 mu g/mL five days after the treatments, and M. azedarach toxins caused a CL sub(50) 173 mu g/mL four days after the treatment. Corrected mortality for O. oryzae and S. frugiperda in the interaction between the bacterial and plant toxins were 11 and 6%, respectively. In the PCR analysis of B. thuringiensis isolates, DNA fragments were enlarged and corresponded to the cry1 and cry2 genes for Bt 1958-2. Thus, it could be concluded that the usage of Bt 2014-2 active against O. oryzae larvae; Bt 1958-2 for S. frugiperda and, for both the insect species, M. azedarach aqueous extract could be used.