INTEGRATED MANAGEMENT OF IMPORTED FIRE ANTS AND EMERGING URBAN PEST PROBLEMS
Location: Imported Fire Ant and Household Insects
Title: Expressed sequence tags from the red imported fire ant, Solenopsis invicta: Annotation and utilization for discovery of viruses
Submitted to: Journal of Invertebrate Pathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 25, 2008
Publication Date: September 1, 2008
Citation: Valles, S.M., Strong, C.A., Hunter, W.B., Dang, P.M., Pereira, R.M., Oi, D.H., Williams, D.F. 2008. Expressed sequence tags from the red imported fire ant, Solenopsis invicta: Annotation and utilization for discovery of viruses. Journal of Invertebrate Pathology. 99(1):74-81.
Interpretive Summary: The red imported fire ant was introduced into the United States in the 1930s and currently infests about 300 million acres. It causes significant economic losses (approximately $5 million) in livestock and agricultural production and poses a threat to human health. USDA-ARS scientists at the Center for Medical, Agricultural and Veterinary Entomology (Gainesville, FL) and the Horticulture and Breeding Research Laboratory (Ft. Pierce, FL) have generated an expression library and sequenced 2300 clones in an effort to discover new pathogens for controlling the red imported fire ant. Six sequences exhibited homology with RNA viruses. Each of these was examined in detail and led to the ultimate discovery of the first virus shown to infect the red imported fire ant. It is hopeful that this virus can be utilized to help control red imported fire ant in the United States.
An expression library was created and 2,300 clones sequenced from a monogyne colony of Solenopsis invicta with the primary intention of discovering viruses infecting this ant pest. After assembly and removal of mitochondrial and poor quality sequences, 1,054 unique sequences were yielded and deposited into the GenBank database under accession numbers EH412746 through EH413799. At least nine expressed sequence tags (ESTs) were identified as possessing microsatellite motifs and 15 ESTs exhibited significant homology with microsporidian genes. These sequences most likely originated from Thelohania solenopsae, a well characterized microsporidian that infects S. invicta. Six ESTs exhibited significant homology with single-stranded RNA viruses (3B4, 3F6, 11F1, 12G12, 14D5, and 24C10). Subsequent additional analysis of these putative viral ESTs revealed that 3B4 was most likely a ribosomal gene of S. invicta, 11F1 was a single-stranded RNA (ssRNA) virus contaminant introduced into the colony from the cricket food source, 12G12 appeared to be a plant-infecting tenuivirus also introduced into the colony as a field contaminant, and 3F6, 14D5, and 24C10 were all from a unique ssRNA virus found to infect S. invicta. The sequencing project illustrates the utility of this method for discovery of viruses and pathogens that may otherwise go undiscovered. The project also provides gene sequences from S. invicta and most likely T. solenopsae that are available publicly through the GenBank database that will certainly facilitate a number of studies concerned with fire ant biology and the epidemiology of its pathogens.