Research Product

Beauveria bassiana spores and metabolites were evaluated for toxicity and pathogenicity to Mysidopsis bahia. Static acute 96-hr tests were conducted with less than or equal to 24-h-old M. bahia using either conidiospores, the mycotoxin, beauvericin, or a nonpolar extract of the mycelia. Conidiospore densities of greater than or equal to 1.5 X 106/ml caused high mortalities. These mortalities were attributed to a high particulate density since heat-killed controls also proved lethal. Beauvericin, a cyclic depsipeptide produced by some strains of B. bassiana, was toxic at an LC50 of 0.56 mg/L. The toxicity of beauvericin persisted in sterile seawater for at least 3, but not 8 weeks. A nonpolar extract of mycelia from B. bassiana containing beauvericin was toxic at an LC50 of 84.2 mg/L. In contrast, a nonpolar extract of mycelia from the fungal weed pathogen, Colletotrichum gloeosporioides f.sp. aeschynomene, was not toxic when tested up to 70.4 mg/L.