Efficacy of Beauveria Bassiana and Bacillus Thuringiensis Against Maize Stem Borer Chilo Partellus (Swinhoe) (Lepidoptera: Pyralidae)

Abstract

Biocontrol potential of Beauveria bassiana (Balsamo) Vuillemin and Bacillus thuringiensis (Berliner) was investigated under laboratory conditions against maize stem borer Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae). Three dose rates of B. bassiana (1 × 104, 1 × 106 and 1 × 108 conidia/ml) and one of B. thuringiensis (0.75 µg/g) were applied alone and in combination against 2nd and 4th larval instars of C. partellus. Larval mortality, pupation, adult emergence, mycosis and sporulation varied against different individual concentrations of B. bassiana and its integrated application with B. thuringiensis. Results of the experiment revealed that combined application of highest concentration of B. bassiana (1 × 108 spores/ml) and B. thuringiensis (0.75 µg/g) exhibited highest larval mortality both in 2nd and 4th instars larvae of C. partellus. The mortality data also demonstrated that 2nd instar larvae were more susceptible to the tested microbial treatments than 4th larval instars. Moreover, less pupation and adult emergence was observed in combined treatments of entomopathogens rather than their individual applications. Maximum mycosis and sporulation was recorded in the cadavers of C. partellus where B. bassiana was applied alone at dose rate of 1 × 104 conidia/ml. These outcomes suggest that combined application of B. bassiana and the toxic protein produced by B. thuringiensis could be a promising ecofriendly approach for the successful management of maize stem borer.