Effect of Combinations of Vairimorpha necatrix (Kramer) with Antibiotics on the Susceptibility of Spodoptera litura (Fabricius)


  • Tamil Nadu Agricultural University, Department of Agricultural Entomology, Coimbatore, Tamilnadu, 641 003, India


Vairimorpha necatrix (Kramer) was combined with different antibiotics to increase its pathogenicity. It was administered to third instar larvae of Spodoptera litura (Fabricius) under laboratory conditions by diet surface treatment and the mortality and spore yield was studied. Reproductive spores of V.necatrix at 106 spores/ml were mixed with 100 ppm of antibiotics viz. gentamycin, oxytetracycline, ampicillin, kana mycin and chloramphenicol. The results showed that the larval mortality due to various Vairimorpha antibiotic combinations ranged from 10 to 62.07 per cent and it was high compared to prepupal and pupal stages. Assessment of spore yield in the infected larvae, pre-pupae and pupae revealed that larval stages recorded higher production of spores which ranged from 0.23 to 2.36 x 1010 spores for larva, 2.26 to 5.28 x 109 spores for pre pupa and 0.28 to 2.23 x 109 spores for pupa. Among the various combinations, Vairimorpha-gentamycin combination produced higher mortality and spore yield of V. necatrix.


Antibiotics, Mortality, Spodoptera litura, Spore Yield, Vairimorpha necatrix.

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