Effect of mass multiplication media on sporulation, field efficacy and shelf life of Beauveria bassiana against rhizome and pseudostem weevils of banana.

Abstract

The pseudostem weevil, Odoiporus longicollis (Olivier) and rhizome weevil Cosmopolites sordidus (Germar) are considered as major insect pests of banana in all the countries of the world. Studies were made on the virulence of the fungal pathogen Beauveria bassiana against these pests in relation to the mass production media and also the method of application under field conditions. Among the various methods, spraying the conidia spore suspension of B.bassiana 17-6 and immersion of the weevils in spore suspension recorded 100% adult mortality of both pseudostem and rhizome weevils in 6 days. Use of rice chaffy grains recorded maximum spore production (6 × 1010 CFU g-1) and significant mortality. Of the different methods of application, traps swabbed with rice chaffy grain formulation registered higher degree of weevil catch reduction in infestation levels and yield of banana than the maize formulation. Our study showed that the use of 17-6 isolate of B.bassiana has potential as a biological control agent of rhizome and pseudostem weevils.