EFFECT OF BEAUVERIA-BASSIANA AND ITS TOXINS ON MYSIDOPSIS-BAHIA (MYSIDACEA)

Beauveria bassiana spores and metabolites were evaluated for toxicity and pathogenicity to Mysidopsis bahia. Static acute 96-h 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 10(6)/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, which contained approximately 1% beauvericin by weight, 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.