Laboratory and Field Evaluations of Four Strains of Beauveria Bassiana As an Endophytic Fungal Entomopathogen in Cotton

The fungus, Beauveria bassiana, is a well-known entomopathogenic fungi that has been used for decades as an inundative biological control agent against many insect pests in multiple crops worldwide. More recently, B. bassiana has also been shown to be capable of living within many plants including cotton as an endophyte. Several beneficial effects of its presence as an endophyte have been reported such as enhanced plant growth and increased resistance to insects and pathogens. The objective of this study was to evaluate the effects of four B. bassiana strains as endophytes in cotton for their effects on plant performance and insect resistance under both lab and field conditions. Plants were grown from seeds treated with two sources of fungal inoculum, spores and biomass, applied to two different major commercial cotton varieties. In the lab, we evaluated endophyte colonization efficiency and resistance to cotton aphids. In field trials, we tested for treatment effects against cotton aphids and thrips, and evaluated plant performance variables across the growing season including stand density, plant height, square and boll retention, and final yields.