Author
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Pereira, Roberto |
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Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 3/17/2004 Publication Date: 5/26/2004 Citation: Pereira, R.M. 2004. Occurence of Myrmicinosporidium durum in red imported fire ants, Solenopsis invicta, and other new host ants in eastern United States. Journal of Invertebrate Pathology. 86:38-44. Interpretive Summary: A researcher of the USDA-ARS, Center for Medical, Agricultural and Veterinary Entomology in Gainesville, FL has discovered a new disease attacking red imported fire ants, and 5 other ant species. The disease is caused by a fungus known as Myrmicinosporidium durum that produces dark, thick-walled spores, in several parts of the ant body. Infections in fire ant colonies were as high as 31%, but generally lower than for other ants such as the thief ant Solenopsis carolinensis, a close relative of the imported fire ant. If this disease can be used as a biological control of red imported fire ants, it may represent one more tool for future management of these pest ants. Technical Abstract: Myrmicinosporidium durum is a parasitic fungus in several ant species that produces dark, thick-walled spores, which can be seen through the insect cuticle. Five new hosts for this fungus, all collected in the eastern United States are reported, including Solenopsis invicta Buren. Ants were collected using several methods including pitfall traps, battery-operated vacuum cleaner, baited traps, and plastic tubes inserted directly into ant nests. Ant specimens were examined under dissecting scope, light or phase microscope, mature spores were measured and infection rates were estimated. This is the first report of Myrmicinosporidium durum in the ants Paratrechina concinna, Pheidole tysoni, Pyramica membranifera, Solenopsis carolinensis, Solenopsis invicta, and Pogonomyrmex badius, and the first reports of this fungus in eastern United States (from the states of Florida and Tennessee). Spores can be found in most parts of the ant bodies. Mature spores are dark brown while immature spores vary from a clear to light brown. The disease can be recognized by the darker than normal color of the ants carrying mature spores. Spores observed in the different hosts were 47-57 µm in diameter. For ant samples where the disease was detected, infection rates varied between 4 and 83% of the ants, or 4 to 100% of the colonies. Infection was most common in S. carolinensis with rates between 17 and 83%. Infection rates for S. invicta were lower than for other ants, however, infection rates within the infected colonies were as high as 31%. Disease observations here were mostly from late summer and fall. Possible implications of this new disease in red imported fire ants are discussed. |
