POTENTIAL OF THREE BIOLOGICAL CONTROL AGENTS FOR SUPPRESSION OF SOLENOPSIS INVICTA, THE RED IMPORTED FIRE ANT

Abstract:
Three potential biological control organisms, a fungus Beauveria bassiana, a protozoan Thelohania solenopsis and a parasite, Solenopsis daguerrei are being evaluated in the field to suppress fire ant populations. All of these organisms have some detrimental effect on fire ants in the laboratory but little is known what effect they have on field populations. Although B. bassiana gave complete mortality of ants in the laboratory, no mortality was observed when it was mixed with the potting soil and fire ants were exposed. This fungus did seem to stimulate colony movement. If the soil was sterilized, then this fungus was more lethal to the ants, especially the brood and queens. The fungus was effective against ants in media with little or no organic matter such as vermiculite or sand. However, for practical control of fire ants in potting media, B. bassiana does not work. In the laboratory colonies infected protozoan with this disease Thelohania solenopsis quickly died and it was very effective in the field in reducing the size and number of fire ant colonies. However, much more research needs to be done before this disease can be introduced into the United States. Still this organism appears to have great promise as a potential biological control organism of fire ants. It has been reported in the literature that the parasite Solenopsis daguerrei will kill the queen, and is very specific for fire ants. However, it is cyclic and does not seem to be very lethal to the fire ant colonies in Argentina. Although it probably has a draining effect on the host colony.