Effect of the Microsporidium Thelohania solenopsae (Microsporida: Thelohaniidae) on the Longevity and Survival of Solenopsis richteri (Hymenoptera: Formicidae) in the Laboratory

Abstract

The longevity of colonies of the black imported fire ant, Solenopsis richteri Forel, and the survival of starved workers and sexual females was compared between healthy colonies and colonies infected with the microsporidium Thelohania solenopsae Knell, Allen, & Hazard. The colonies were collected in the field and reared for approximately four mo. Individual workers and sexuals were held without food until death. The body weight of infected and healthy workers was compared. After 3 mo of laboratory rearing, longevity of infected colonies was significantly shorter than that of healthy ones; mortality of infected colonies was 92% and mortality of healthy colonies was 49%. At 27°C, mortality rate of workers from infected colonies was higher than in healthy workers. Workers from infected colonies lived between 8.8 and 29.2% less than healthy workers. At 22°C, no statistical significance was observed. At 21°C, only the initial mortality of sexual females was higher in infected than in healthy individuals. The weight of infected workers was very similar to that of healthy workers. T. solenopsae should be considered for the biological control of the imported fire ants in the United States.