Prevalence and impact of the microsporidium Thelohania solenopsae (Microsporidia) on wild populations of red imported fire ants, Solenopsis invicta, in Louisiana

• Published in: Journal of invertebrate pathology Vol. 97; no. 2; pp. 91 - 102
• Main Authors: Milks, Maynard L., Fuxa, James R., Richter, Arthur R.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.02.2008; Elsevier
• Subjects: Animals; Ants - microbiology; Biological and medical sciences; Biological control; Brood; Colony size; Commercial waterway; Control; disease prevalence; ecological factors; environmental factors; fire ants; Formicidae; Fundamental and applied biological sciences. Psychology; geographical distribution; infection; insect brood; insect colonies; Logistic Models; Louisiana - epidemiology; Microsporidia; Microsporidia, Unclassified - pathogenicity; microsporidiosis; Microsporidiosis - epidemiology; Microsporidium; Models, Statistical; monogyne colonies; Phytopathology. Animal pests. Plant and forest protection; polygyne colonies; Prevalence; Protozoa. Invertebrates; Social form; Solenopsis invicta; Thelohania - pathogenicity; Thelohania solenopsae; worker insects; Worker mass; Louisiana; United States; North America; America; Thelohania solenopsae; Brood; Colony size; Commercial waterway; Social form; Worker mass; Solenopsis invicta; Entomopathogen; Prevalence; Insecta; Biological control; Formicoidea; Microsporidia; Fungi; Pest; Microbiological control; Aculeata; Formicidae; Parasite; Social insect; Mycoparasite; Arthropoda; Colony; Hymenoptera; Invertebrata; Population density
• DOI: 10.1016/j.jip.2007.08.003
• ISSN: 0022-2011

We surveyed 165 sites to determine the ecological factors that might influence the distribution and prevalence of Thelohania solenopsae, and its effect on the demography of the red imported fire ant ( Solenopsis invicta) in Louisiana. The microsporidium was found in 9.9% of colonies and at 16% of sites. Its distribution was clumped within the state with the majority of infected colonies and sites occurring in two infection patches. The proportion of polygyne colonies was a strong (positive) predictor of the proportion of infected colonies at a site. Infected monogyne colonies, however, still accounted for nearly 20% of infected colonies, a much higher proportion than anticipated. Several other factors, including the numbers of colonies at a site, precipitation, proximity to commercial waterways and ports, and type of habitat were also retained in the multiple logistic regression model describing T. solenopsae prevalence. The microsporidium appears to adversely affect the occurrence of brood, and possibly the size of S. invicta colonies and the mass of workers. It, however, was not included in the multiple regression model of the number of colonies or the density of ants at a site. Although our findings do not imply causation, they have identified several variables that might influence the epizootiology of T. solenopsae. Future work should concentrate on experimentally manipulating these variables to confirm these relationships.