Monogyne RIFA Colony Development and Production

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Chapter 2 – Literature Review

History of Imported Fire Ants in the United States

In 1918, the Black Imported Fire Ant (BIFA), Solenopsis richteri Forel, was transported from South America to the United States in ship ballast and cargo. The ants were first observed near seaports located in Mobile, AL (Creighton 1930). In the 1930s, a second species, the red imported fire ant (RIFA), Solenopsis invicta Buren, was also introduced from South America into Mobile, Al (Buren 1972). The two imported fire ant species were originally identified as Solenopsis savevissima richteri, “dark phase” and “light phase” (Wilson 1952), until Buren (1972) named the light phase ant S. invicta. Since their introduction, many control efforts have been aimed at eliminating, or at least, slowing the spread of imported fire ants (IFA). However,in spite of management efforts, IFAs have continued to establish colonies throughout the United States, and now range from Florida to California.Although both imported fire ant species originated in South America, the ants differ in their native distribution and range. Populations of S. richteri occur in Uruguay, central eastern Argentina, and southern Brazil (Tschinkel 2006) whereas S. invicta has a much larger distribution inhabiting areas in Argentina, Uruguay, along the Pantanal River basin, and in Brazil (Allen et al. 1974, Tschinkel 2006, Folgarit et al. 2008). Currently, not much is known about the exact origin or initial geographic spread of IFAs in South America. However, the origin and spread of imported fire ants in the U.S. has been well documented (Canter 1981, Callcott and Collins 1996). IFAs initially spread out from Mobile, Al at rate of one mile per year between 1918 and 1932 (Callcott and Collins 1996) into
the surrounding counties via mating flights and human transport. Between 1932 and 1950, the IFAs rate of spread from Mobile, AL reportedly increased to three miles per year (Callcott and Collins 1996).

Control History and Current Distribution

In response to the rapid spread of RIFA throughout the southern states, the United States Department of Agriculture (USDA) instituted a $2.4 million federal and state fire ant eradication and control program in 1957 (George 1958, Lockley and Collins 1990). The goals of the program were to survey and identify imported fire ant infested areas and to treat these infested areas with government approved pesticides (Williams et al. 2001).The first active ingredients deemed appropriate for fire ant control were dieldrin, heptachlor, and chlordane (George 1958). As part of the fire ant eradication program the Plant Pest Control Division of the USDA, and Southern Plant Board developed an extensive spray regimen using these residual pesticides (George 1958). Initially, heptachlor and dieldrin were applied aerially or on the ground at a rate of 2 lbs of active ingredient per acre. However, these applications caused a great deal of damage to the environment and also caused significant mortality in bird and mammal populations (Tschinkel 2006). As a result, in 1959, the USDA lowered the application rate of these pesticides to 1.25 lbs of active ingredient per acre. The aerial applications of heptachlor and dieldrin were terminated in 1962 (Williams 1983) following the U.S. Food and Drug Administration’s discovery of epoxide residues in meat and milk. By this time, $15 million dollars had been spent to control the fire ant (Williams et al. 2001,Tschinkel 2006). Yet unfortunately, the spray control program was a complete failure because the fire ant managed to increase its range from 8 million to 12 million hectares of land during the three year control period (1959-1962) (Tschinkel 2006).Before usages of heptachlor and dieldrin were halted, researchers from the USDA and several institutions began developing chemical baits for fire ant control. Researchers wanted to develop bait that could be easily formulated of low cost materials, was easily applied, was not easily degraded by rain, and was non-toxic to non-target organisms. The first bait resulting from this research was Mirex. Mirex contained the active ingredient mirex (nerve poison) formulated in soybean oil and carried on corncob grit. In 1961, Mirex took the place of heptachlor as the premiere fire ant control product (Lofgren and Vander Meer 1986). That same year, aerial and ground applications of Mirex began. Initially, Mirex was applied at a rate of 11.2 kg/hectare, but by 1965 this amount was reduced to 1.4 kg/hectare because lower application rates of mirex still provided desirable control results (Tschinkel 2006). In early studies conducted by Lofgren et al. (1964) mirex showed great promise. Lofgren et al. (1964) reported that Mirex could provide 90-100% control in research plots. Based on this study, the USDA believed that imported fire ants could, in fact, be eradicated from the U.S. To test the efficacy of Mirex in the field, the USDA established research sites in Savannah, GA, Tampa-St. Petersburg, FL, and Columbus-Starkville, MS (Banks et al. 1973). Two treatment blocks of variable size were constructed in each city, and Mirex was applied three times aerially at a rate of 2.5 lb/acre or 1.25 lb/acre. Banks et al. (1973) reported near 100% colony mortality in all treatment plots except two. One surviving colony was found in a research plot at the Savannah, GA research site and several colonies were found in a research plot located in Tampa-St. Petersburg, FL. However, even in locations where Mirex provided near complete control, the fire ants were able to reinfest the treated areas within 3-6 months after treatment. Although, the ants quickly re-colonized in the treated areas, Banks et al. (1973) still argued that eradication of the fire ant in the U.S. was possible. Therefore,approximately 800,000 lbs of Mirex was dispersed over 140 million of acres of land between 1962 and 1978 (Williams et al. 2001). However, as with heptachlor, Mirex was found to be a severe environmental contaminant. In 1978, the EPA cancelled Mirex’s registration after high levels of mirex residues were discovered in the environment, fresh water fish, and other nontarget organisms (Kaiser 1978)


List of Tables
List of Figures
Chapter 1 Introduction
Chapter 2 Literature Review
2.1 History of Imported Fire Ants in the United States
2.1.1 Control History and Current Distribution
2.1.2 Current Range in the U.S
2.2 Imported Fire Ant Identification and Biology
2.2.1 Morphology
2.2.2 Monogyne RIFA Colony Development and Production
2.2.3 Pleometrosis
2.2.4 Monogyne Colony Foraging and Territorial Behavior
2.2.5 Discovery of Polygyny in U.S. Fire Ant Colonies
2.2.6 Origins of Polygyny and Colony Founding Behavior
2.2.7 Budding
2.2.8 Polygyne Colony Foraging and Territorial Behavior
2.2.9 Polygyne Colony Production
2.3 Ecological Impacts
2.3.1 RIFA Impacts on Arthropod Biodiversity
2.3.2 RIFA Impacts on Arthropod Pests and Beneficial Arthropods
2.3.3 RIFA Impacts on Birds
2.3.4 RIFA Impacts on Reptiles
2.3.5 RIFA Impacts on Mammals
2.3.6 RIFA Impacts on Cattle
2.3.7 RIFA Impacts on Crops
2.3.8 RIFA as Potential Biological Control Organisms
2.3.9 RIFA Impacts in the Urban Environment
2.4 Current Control Methods
2.4.1 Broadcast Control Methods/Baits
2.4.2 Granular Formulations
2.4.3 Individual Mound Treatments (IMTs)
2.4.4 Combination Treatment Methods
2.4.5 Biological Control Agents/Fungi
2.4.6 Viruses
2.4.7 Fire Ant Decapitating Phorid Flies
2.4.8 Microsporidia
2.4.9 Areawide Suppression Program
2.5 Predicting the Spread
Chapter 3 Comparison of three broadcast fire ant control products and an individual mound treatment to control fire ant colonies in
3.1 Introduction
3.2 Materials and Methods
3.3 Results
3.4 Discussion
Chapter 4 Effects of two broadcast fire ant control products
on non-target ant species in Virginia
4.1 Introduction
4.2 Materials and Methods
4.3 Results
4.4 Discussion
Chapter 5 Characterization of Solenopsis invicta
(Hymenoptera: Formicidae) populations in Virginia:
Social form genotyping and pathogen/parasitoid
5.1 Introduction
5.2 Materials and Methods
5.3 Results
5.4 Discussion
Chapter 6 Predicting the potential range expansion of the red
imported fire ant, Solenopsis invicta, in
6.1 Introduction
6.2 Materials and Methods
6.3 Results
6.4 Discussion


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