J Cristian Vidal-Quist1, Pedro Castañera, Joel González-Cabrera. 1. Unidad Asociada de Entomología IVIA (Instituto Valenciano de Investigaciones Agrarias)-CIB (Centro de Investigaciones Biológicas) del Consejo Superior de Investigaciones Científicas (CSIC), Valencia, Spain.
Abstract
BACKGROUND: Ceratitis capitata (Wiedemann) is one of the world's most destructive fruit pests. The aim of this study was to ascertain insecticidal activity of Bacillus thuringiensis (Berliner) delta-endotoxins to C. capitata. RESULTS: Among 42 selected Bacillus strains, only B. thuringiensis serovar israelensis (Bti) solubilised protoxins showed biological activity against C. capitata neonate larvae, whereas Bti spore and crystal mixture was inactive. Insecticidal activity of Bti protoxins was significantly enhanced by incubation with Culex pipiens L. gut extracts. Overdigestion of Bti protoxins with Sesamia nonagrioides (Lefebvre) gut extracts suppressed biological activity against C. capitata, and this correlated with degradation of Cyt toxins. Cyt1Aa solubilised protoxin showed the highest toxicity, LC(50) after 7 days of 4.93 microg cm(-2), while proteolytical processing of Cyt1Aa protoxins by larval gut extracts did not enhance insecticidal activity. CONCLUSION: The present study provides evidence for the first time of the insecticidal activity of a B. thuringiensis strain against C. capitata and identifies a single delta-endotoxin with potential for controlling this pest. (c) 2010 Society of Chemical Industry.
BACKGROUND:Ceratitis capitata (Wiedemann) is one of the world's most destructive fruit pests. The aim of this study was to ascertain insecticidal activity of Bacillus thuringiensis (Berliner) delta-endotoxins to C. capitata. RESULTS: Among 42 selected Bacillus strains, only B. thuringiensis serovar israelensis (Bti) solubilised protoxins showed biological activity against C. capitata neonate larvae, whereas Bti spore and crystal mixture was inactive. Insecticidal activity of Bti protoxins was significantly enhanced by incubation with Culex pipiens L. gut extracts. Overdigestion of Bti protoxins with Sesamia nonagrioides (Lefebvre) gut extracts suppressed biological activity against C. capitata, and this correlated with degradation of Cyt toxins. Cyt1Aa solubilised protoxin showed the highest toxicity, LC(50) after 7 days of 4.93 microg cm(-2), while proteolytical processing of Cyt1Aa protoxins by larval gut extracts did not enhance insecticidal activity. CONCLUSION: The present study provides evidence for the first time of the insecticidal activity of a B. thuringiensis strain against C. capitata and identifies a single delta-endotoxin with potential for controlling this pest. (c) 2010 Society of Chemical Industry.