Growth of Beauveria bassiana in Fire Ant Nest Soil with Amendments

Abstract

Studies evaluated the capacity of Beauveria bassiana (Bals.) Vuill. to grow, spread, and sporulate in soil from fire ant ( Solenopsis invicta Buren) nests, with or without nutrient amendments. Amendments included fire ant carcasses, chitin, and rice. Soil obtained from fire ant nests was inoculated with B. bassiana as mycelial mats, conidial suspension, or infected cadavers. No significant differences in colony diameters were detected among the nonsterile soil treatments regardless of inoculum type, but in sterile soil amended with ants or rice, fungal colonies were significantly larger than colonies on control or chitin-amended soil. CFU counts also showed similar results. Ground rice and either sodium dodecyl sulfate-clean or natural ant carcasses showed equally beneficial effects on fungal growth in sterile soil. Results suggest that addition of tested amendments to the nest soil, as would be accomplished by formulation of microbial insecticides, may not offer any advantage to the development of epizootics of B. bassiana in fire ant nests.