FIELD APPLICATIONS OF BEAUVERIA-BASSIANA FOR CONTROL OF THE RED IMPORTED FIRE ANT (HYMENOPTERA, FORMICIDAE)

A Beauveria bassiana (Balsamo) Vuillemin isolate (Bb447), recovered fr om the red imported fire ant, Solenopsis invicta Buren, in Brazil was applied to fire ant mounds in Florida pastures. Rice with Bb447 applie d to the tops of mounds resulted in a maximum infection of 55% of the live ants sampled; 70% of the treated mounds remained active or formed active new mounds within 8 wk. Injections of conidial powder formulat ions of Bb447 in late fall and early summer resulted in peak infection s of 60 and 52% of live ants sampled, respectively. All of the injecte d mounds remained active or formed active new mounds within 8 wk after treatment. Injection of Bb447 mixed with, a hydrophobic silica carrie r resulted in a 52% reduction in active mounds. Injection of the silic a carrier alone resulted in a 41% reduction. Foraging by the red impor ted fire ant was reduced significantly in areas within which mounds we re injected with fungal formulations, whereas foraging by other ant sp ecies increased in these areas.