Beauveria bassiana as an Endophyte in Tissue-Cultured Banana Plants: a Novel Way to Combat the Banana Weevil Cosmopolites sordidus

Beauveria bassiana, which is effective against a range of insect pests, is the most researched and commercialised fungal biopesticide. Laboratory and screenhouse studies have revealed that this entomopathogenic fungus has great potential for use against the banana weevil, Cosmopolites sordidus. However, impractical field delivery methods and high costs associated with the application of B. bassiana prevent its use and commercialisation in banana fields against C. sordidus. Our research has revealed that B. bassiana can colonise internal banana tissues for at least 4 months after tissue-cultured plantlets are dipped in a spore suspension. The type of banana cultivar did not affect colonisation by B. bassiana, and, even when elevating doses, plant growth was not reduced. In a set of three screenhouse experiments, larval mortality rates in B. bassiana-treated plants were 24-89%, and the presence of the fungus led to a reduction in larval damage of >50%. Application of B. bassiana as an endophyte could circumvent bottlenecks associated with its application as a conventional biopesticide.