Evaluación de cepas nativas de Bacillus thuringiensis Berliner para el control de Heliothis virescens Fabricius en el cultivo del tabaco en Cuba

liquid culture of eight bacillus thuringiensis strains were evaluated on second instar larvae of heliothis virescensfabricius. lbt-111 strain showed 50% of mortality the second day of experiment. a second bioassay with this strain allowed to determinate the cl50 against heliothis virescens, which was 2.6 x 107 spores/ml-1 and the highest correlation (0.95) was obtained with the data of 48 h. the confidence limits (p 0.05) in the dosis-probit correlation line showed narrow margins with the data of 48 h, which indicate the accuracy in the calculation of the cl50.