Author
 |
Pereira, Roberto |
|
Submitted to: Meeting Abstract
Publication Type: Proceedings Publication Acceptance Date: 10/2/2003 Publication Date: 10/30/2003 Citation: Pereira, R.M. 2003. Areawide suppression of fire ant populations in pastures: project update. Annual Red Imported Fire Ant Conference. p. 57. Interpretive Summary: Technical Abstract: Project Importance and Rationale The red imported fire ant, Solenopsis invicta, is an invasive species inadvertently introduced into the USA and infests over 321 million acres in 12 southeastern states and Puerto Rico (Callcott et al. 1996, Code of Federal Regulations 2001). The fire ant thrives in disturbed habitats where people are likely to be present. The ant's potent sting and large populations have created serious medical and agricultural problems. About 40 percent of the human population in infested areas is stung each year. Medical attention is required in many severe cases and some result in death due to strong allergic reactions (deShazo et al. 1999). Fire ants also reduce populations of native ants and other insects, as well as many other animals (Porter and Savignano 1990, Jusino-Atresino and Phillips 1994, Wojcik 1994). Fire ants damage many crops and create problems for the cattle industry. Imported fire ants inhabit million acres of pasture in twelve southern states from Texas to Virginia and become established in some areas in California, Arizona, and New Mexico. The economic impact of fire ants in the US economy is estimated to approximately $6 billion dollars annually in damage, control measures, and medical treatments (Pereira et al. 2002). Chemical treatments can provide fast control in limited areas, but are costly and provide only temporary fire ant suppression. Treatment of pastures is usually cost-prohibitive, and a rare practice in the US pasturelands. There are only two commercial toxic bait treatments available for fire ant control in pasture. These baits are non-specific, costly and require multiple treatments per year, and continuous use for as long as fire ants are a problem. The continuous treatment/re-invasion process perpetuates the ecological balance originally upset by the invading imported fire ant. Fire ant densities in the United States are about five times those found in their indigenous South America, most likely because in the United States they have escaped from their native natural enemies (Porter et al. 1992, Porter et al. 1997). To resolve this issue, natural enemies of fire ants, such as parasitic phorid flies and a microsporidian pathogen are being evaluated to develop self-sustaining, biologically-based integrated pest management strategies for permanent or long term suppression of fire ants in the U.S. The decapitating flies, Pseudacteon tricuspis and other species in the same genus, and the microsporidian ant pathogen, Thelohania solenopsae, have been successfully established in several states in the past few years (Williams et al. 2003). The prevalence of these biocontrol agents continues to increase in many release sites where they have been established. These self-sustainable biocontrol agents are important stressors to fire ant populations and can impact the pest populations over wide areas. Pseudacteon flies are very host specific flies (Porter et al. 1995, Porter & Alonso 1999) that complete their development within the fire ant head, causing them to fall off. The flies cause direct mortality of fire ants, but its most detrimental effect may be the reduction of foraging opportunities and consequent weakening of fire ant colonies. Thelohania solenopsae is also very host specific, infecting only red, black, and red/black hybrid fire ants. It causes a chronic disease in worker and reproductive ants that can be transmitted transovarially to the brood, and horizontally to other ants. The disease causes a slow death of the colony (Williams et al. 1999), and makes ants more susceptible to the insecticide hydramethylnon (Valles & Pereira 2002). The primary objective of this project is to demonstrate that fire ant populations can be reduced and maintained at very low levels over a large area using chemical baits in combination with biocontrol agents. T |
