P. S. Shanmugam ¹, R. Balagurunathan ¹, N. Sathiah ¹, N. G. V. Rao ²

Affiliations
1 Department of Agric. Entomology, Tamil Nadu Agricultural University, Coimbatore-641003, Tamil Nadu, IN
2 Department of Biotechnology, Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola-444104, Maharashtra, IN

Abstract

The susceptibility of different instars of Earias vittella (Fabrieius) to Bacillus thuringiensis (Bt) insecticidal proteins (ICP) was studied. The LC₅₀ of CrylAa, CrylAb, Cry1Ac, CryiC and Cry1E were 108.54, 97.04, 66.62, 1240.83 and 1335.60 ng/cm², respectively to E. vittella neonates. The order of toxicity of different ICPs to second and third instar was Cry1Ac > CrylAb > CrylAa. Overlap 95 per cent fiducial limits at LC₅₀ of CrylAa and CrylAb showed similar toxicity of these toxins to second and third instars of E. vittella. The possibility of these toxins and toxicity parameters in resistance management is discussed.

Keywords

Bacillus thuringiensis, Earias vittella, Insecticidal Proteins, Median Lethal Concentration, Toxicity.

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Indira Bhojne ¹, N. R. Supare ¹, N. G. V. Rao ¹

Affiliations
1 Dr. Panjabrao Deshmukh Krishi Vidyapeeth, Akola 441 004, Maharashtra, IN

Abstract

Comparative studies on the efficacy of Bacillus thuringiellsis Berliner var. kurstaki(HD-I) and morrisoni (HD-12), when used alone against second instar larvae of Helicoverpa armigera (Hubner) revealed that the strain kurstaki(HD-l) was more toxic than morrisoni (HD-12). Strain kurstaki (HD-I) could cause 79.38 per cent mortality of second instar larvae of H. armigera at 0.00963 per cent concentration, while morrisoni (HD-12) could cause 89.66 per cent mortality at 0.0576 per cent concentration. The LC₅₀ was 0.0055, whereas that of HD-12 was 0.02%.

Keywords

Bacillus thuringiensis Var, kurstaki, Morrisoni, Helicovejpa armigera.

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