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United States Department of Agriculture

Agricultural Research Service

Title: Infection of Red Imported Fire Ant (Hymenoptera: Formicidae) Colonies with the Entomopathogen Thelohania Solenopsae (Microsporida: Thelohaniidae)

Authors
item Williams, David
item Oi, David
item Knue, Gregory

Submitted to: Journal of Economic Entomology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: April 10, 1999
Publication Date: N/A

Interpretive Summary: Imported fire ants are a significant pest of the southern United States, where the ability to sting, damage crops, and reduce biodiversity make it a concern in urban, agricultural, and wildlife areas. Thelohania solenopsae is a pathogen of imported fire ants that can infect the ovaries of fire ant queens. This pathogen slowly debilitates a queen so that her reproductive capacity diminishes and she eventually dies. Previously, this pathogen wa known only from South America. In 1996, T. solenopsae was discovered in several locations in Florida, and limited surveys throughout the southern U.S. revealed that infections were present in Texas and Mississippi. In this study we provide the first documentation of artificially initiated transmission of T. solenopsae among fire ant colonies by providing colonies with infected immature ants. The laboratory inoculations resulted in significant reductions in immature ants and adults. Lower egg laying rates, queen weights, and queen survivorship was also documented from infected colonies. Artificial inoculations resulting in infections and spread of T. solenopsae among red imported fire ant colonies under field conditions was also demonstrated for the first time. The ability to artificially infect S. invicta colonies with T. solenopsae should facilitate the assessment and development of this pathogen as a biological control agent of imported fire ants.

Technical Abstract: Thelohania solenopsae Knell, Allen, & Hazard, is an entomopathogenic microsporidium that infects imported fire ants. We provide the first documentation of artificially initiated transmission of T. solenopsae among colonies of the red imported fire ant, Solenopsis invicta Buren. Microsporidian transmission was initiated by providing colonies with brood (mixture of eggs, larvae, and pupae) from infected S. invicta colonies. Inoculated laboratory colonies of S. invicta had significantly less brood and adults than control colonies. Lower egg laying rates, queen weights, and queen survivorship was also documented from infected colonies. After 23 to 29 wk, there was 90% less brood in the inoculated laboratory colonies. Thus, T. solenopsae slowly debilitates a S. invicta queen so that her reproductive capacity diminishes and she eventually dies. Artificial inoculations resulting in infections and spread of T. solenopsae eamong red imported fire ant colonies under field conditions was also demonstrated for the first time. KEY WORDS: Solenopsis invicta, fire ant, biological control, pathogen, microbial control, disease

Last Modified: 9/2/2014
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