Evaluation of Entomopathogenic Fungi for the Management of Tobacco Caterpillar Spodoptera litura (Fabricius)

摘要

The efficacy of two entomopathogenie fungi, Beauveria bassiana and Metarhizium anisopliae, against tobacco caterpillar, Spodoptera litura (Fabricius) is a polyphagus noctuid pest inflicting heavy losses on many of the cultivated crops were studied under laboratory and field conditions. The estimated LC_(50)value of B. bassiana and M. anisopliae towards third instar larvae of S. litura were 50.31 x 10s conidia/ml and 16.52 x 10~5 conidia/ml, respectively. The LT value of B. bassiana and M. anisopliaeat the concentration of 10~8 conidia ml~(-1) against third instar larvae of S. litura were 5.49 and 4.79 days, respectively. The incidence of Spodoptera litura population from two rabi crop seasons revealed that S. litura population was positively correlated with maximum temperature, minimum temperature, wind velocity and sunshine hours, whereas negatively correlated with RHI and RHII. The correlation was non significant between maximum temperature, but significant with wind velocity and sunshine hours,while it was negatively non significant with RH -I and negatively significant with RH- II. Field study revealed that the efficacy of entomopatho genie fungi B. bassiana (Bb-L-2) and M. anisopliae (Ma-L-1) strains) was enhanced in combination with the newer molecular insecticide (Spinosad45 SC)@0.009%, Neem oil 5% and NSKE 5% in controlling S. litura larvae and spinosad was found most effective against S. litura. While, the fungus, B. bassiana and M. anisopliae at recommended concentration with spinosadat half recommended dose and at recommended dose of the neem oil and NSKE (Neem seed kernel extract) were found equally effective.