Bioefficacy of some entomopathogenic fungi against thrips, thrips tabaci lindeman on onion crop
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Date
2010
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Publisher
CCSHAU
Abstract
Investigations were carried out to assess the pathogenicity of two entomopathogens, Beauveria
bassiana and Verticillium lecanii against Thrips tabaci on onion crop. Bioassay studies under
laboratory were carried out to determine the LC50 and LT50 values of these entomopathogens against
T. tabaci. Screen house and field studies were carried out to assess the bioefficacy of the
entomopathogens against T. tabaci. The cumulative corrected mortality of T. tabaci due to B. bassiana
ranged from 43.75 - 90.63 per cent at 7 days after treatment (DAT) whereas due to V. lecanii it was
31.34 - 86.57 per cent under laboratory conditions. The LC50 values of B. bassiana and V. lecanii
against T. tabaci were 1.23x107 and 1.82x108 spores/ml, respectively. The LT50 values of B. bassiana
for different concentrations against T. tabaci ranged from 72.42 - 191.90 hours where the lowest LT50
value of 72.42 hours was obtained for the concentration of 1x1012 spores/ml. The LT50 values of V.
lecanii against T. tabaci ranged from 79.61 - 270.41 hours where the lowest LT50 value of 79.61 hours
was obtained for the concentration 1x1012 spores/ml. In screen house experiment with B. bassiana, a
cumulative corrected mortality of 78.48 per cent was observed at 7 DAT for the lab cultured B.
bassiana at the concentration 1.23x108 spores/ml, while the commercial formulation of B. bassiana
(Myco-Jaal, 1x108 spores/ml) recorded a mortality of 78.48 per cent at 7 DAT and the standard check
Fenvalerate 20 EC (0.0075%) gave a mortality of 97.84 per cent. In the case of V. lecanii a cumulative
corrected mortality of 78.88 per cent was observed for the lab cultured V. lecanii at the concentration
1.82x109spores/ml while the commercial formulation of V. lecanii (Phule Bugicide, 2x108 cfu/g)
recorded a mortality of 80.53 per cent and the standard check Fenvalerate 20 EC (0.0075%) gave a
mortality of 99.50 per cent. In field experiments, the lab cultured B. bassiana with concentration of
1.23x109 spores/ml recorded a mortality of 69.40 per cent while the commercial formulation of the
fungus gave a mortality of 73.40 per cent and Fenvalerate 20 EC (0.0075%) gave a mortality of 90.50
per cent. The lab cultured V. lecanii of concentration 1.82x1010 spores/ml gave a mortality of 69.70
per cent and the commercial formulation of the fungus recorded 74.90 per cent mortality, however the
insecticide Fenvalerate 20 EC 0.0075% gave a mortality of 90.10 per cent. The results obtained from
the studies revealed that the entomopathogenic fungi were found effective against T. tabaci.
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Keywords
Diseases, Mutants, Biological phenomena, Wheats, Phenols, Fungi, Sugar, Planting, Rapd, Proteins