Monogyne RIFA Colony Development and Production

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Chapter 3 – Comparison of Three Broadcast Fire Ant Control Products and an Individual Mound Treatment for Control of Fire Ant Colonies in Virginia


Prior to 2009, all reported red imported fire ant (RIFA), Solenopsis invicta Buren,infestations in Virginia were documented and managed by the Virginia Department of Agriculture and Consumer Services (VDACS). However in spite of VDACS’ efforts, RIFA infestations within the state continued to spread. Therefore, in 2009 the United States Department of Agriculture (USDA) in conjunction with VDACS implemented the Imported Fire Ant Quarantine in the following areas of Virginia: the counties of James City and York, and the cities of Chesapeake, Hampton, Newport News, Norfolk, Poquoson, Portsmouth, Suffolk,Virginia Beach and Williamsburg. Consequently, VDACS is no longer responsible for treating RIFA mounds in the quarantined areas. Fire ant control in the quarantined counties/cities is now the responsibility of homeowners, nurseryman, and pest management professionals. However,VDACS is still responsible for managing RIFA infestations in cities outside of the designated quarantine areas.The VDACS standard control method for treating RIFA mounds in Virginia was to apply MaxForce® fire ant bait (1.0% hydramethylnon) (Bayer CropScience, Kansas City, MO) around each active mound. Bait applications were followed sixweeks later by an acephate mound drench. Although effective, these individual mound treatments (IMT) required that all target mounds be located before application. IMTs are labor intensive and time consuming, but the direct application of the chemical to the mound enhances the chance of insecticidal contact with colony members (Barr and Best 1999).Baits and liquid insecticides are the typical formulations used for IMTs, but aerosols,granules, and dusts can also be used. IMTs are useful when 20 or fewer mounds are present in an acre of land (Barr and Best 2002). IMTs are also beneficial because they are only applied to visible RIFA mounds, thus preventing native ant mortality. However, because IMTs are only applied to visible mounds, fire ant recolonization can easily occur in treated areas where small mounds are not obvious. Quite often multiple applications are necessary to control all mounds in a particular area. In contrast to IMTs, broadcast insecticide treatments for RIFA do not require individual mounds to be located. These products are generally applied at locations where mound densities exceed 30-40 per hectare. Therefore, application time and labor is decreased when broadcast products are used. Broadcast fire ant control products are currently formulated as either granules or baits.The active ingredient in fire ant bait is often combined with soybean oil or some other food matrix that is attractive to foraging fire ants (Williams et al. 2001). Broadcast baits are applied using either a hand or tractor mounted spreader (Drees et al. 1996). Once the ants transport the bait inside the colony, the ants transfer the active ingredient throughout the colony by trophallaxis. Because the active ingredients found in baits are spread throughout the colony by the worker ants, several weeks to months may pass before significant colony mortality occurs (Drees et al. 2006). Although colony suppression may take longer using broadcast baits, studies have indicated that individual mound treatments are more costly than and not as effective as some of the more novel broadcast bait products (Barr and Best 1999). Broadcast fire ant products have been used to treat fire ants in Virginia, but they have been infrequently used, due to VDACS’ preference for individual mound treatments. Because VDACS relinquished their responsibility to treat infestations in quarantined counties and cities,residents in these locales will have to learn to manage fire ants on their own. With the quarantine implementation, the need for broadcast RIFA product evaluations and other control recommendations are vital to Virginia.Two of the leading broadcast fire ant control products are Advion® fire ant bait (Indoxacarb 0.045%; DuPont, Wilmington, DE) and Top Choice granular (Fipronil 0.143%;Bayer Environmental Sciences, Cary, North Carolina). Advion is a fast acting bait (Furman and Gold 2006) that contains the active ingredient, indoxacarb, which belongs to the oxadiazine chemical class. Oxadiazines block sodium channels in the nerve axon. Immediately after bait ingestion, feeding begins to decrease and target individuals usually succumb to death within 48 hours (Barr 2002). Top Choice contains the active ingredient fipronil which belongs to the phenylpyrazole chemical class. Fipronil is a nerve poison that blocks the passage of chloride ions through GABA receptor and glutamate-gated chloride channels causing nerve hyperexcitation in target insects (Kolaczinski and Curtis 2001). Previous studies have shown that Advion significantly reduced fire ant foraging 24 hours after treatment (Barr 2004) and eliminated > 95% of colonies after one week (Hu and Song 2007) after application. Top Choice has a longer residual activity than Advion but is much slower acting. Barr and Best (2004) reported that Top Choice® reduced the mean number of active fire ant mounds by 80% five weeks after treatment and greater than 90% control was observed 52 weeks later.

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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 Virginia
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 detection
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 Virginia
6.1 Introduction
6.2 Materials and Methods
6.3 Results
6.4 Discussion


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