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United States Department of Agriculture

Agricultural Research Service

Research Project: Areawide Management of Imported Fire Ants

Location: Biological Control of Pests Research Unit

2012 Annual Report


1a.Objectives (from AD-416):
The imported fire ants are serious pests affecting humans, wildlife, crops, and livestock, as well as a health hazard to humans. The goal of this project will be the development of management tools for a sustainable reduction of imported fire ant populations. To achieve this goal a proactive area-wide program will be implemented to suppress imported fire ant populations and to end the spread of infestations. A regional management program developed with Mississippi State University will include product testing, natural history, ecology, and biological control.


1b.Approach (from AD-416):
Cultural, biological, and chemical control methods need to be integrated into proactive, regional fire ant management programs. New bait technologies utilizing synthetic chemicals and microbials will be evaluated to identify the most effective treatments for implementation into large scale programs. Native species of ants will be inventoried to compare diversity of native ant species with abundance of imported fire ants either naturally or under different management strategies. Area-wide programs will be implemented through cooperation with the Mississippi Agricultural and Forestry Experiment Station. Information will be coordinated with the ARS Information Office and the Mississippi State University Extension Service.


3.Progress Report:

I. Surveys of exotic and native species of ants in midsouthern United States. Numerous surveys and collections of ants were made in the region: Florida: Apalachicola Bluffs and Ravines Preserve (Liberty County (Co.)), Apalachicola National Forest (N.F.). Torreya State Park (Liberty Co.), and Tall Timbers Research Station (Leon Co.); Georgia (GA): Covington (Newton Co.), Gordon (Wilkinson Co.), River Creek Wildlife Management Area (WMA) (Thomas Co.), and the Wade Tract (Thomas Co.); Mississippi: Upper Sardis WMA (Lafayette Co.), Delta National Forest (N.F.) (Sharkey Co.), John Kyle State Park (St. Pk) (Panola Co.), Lefleur's Bluff St. Pk. (Hinds Co.), Lake Lincoln St. Pk. (Lincoln Co.), Percy Quin St. Pk. (Pike Co.), Tombigbee N.F. (Winston Co.), Noxubee National Wildlife Refuge (Noxubee, Oktibbeha, & Winston Cos.), DeSoto N.F. (Forrest Co.), Holly Springs N.F. (Benton Co.), Jackson Sandhill Preserve (George Co.), Natchez Trace Parkway (Choctaw, Pontotoc, & Lee Counties), and various Gulf Coast localities (Jackson, Harrison, and Hancock Cos.); Tennessee: Big Hill Pond St. Pk. (McNairy Co.), Carroll Cabin Barrens (Decatur Co.), Cedars of Lebanon St. Pk. (Wilson Co.), Natchez Trace Parkway (Wayne and Lewis Cos.), Tennessee Welcome Center (Giles Co.), and the Wolf River WMA. (Fayette Co); and Texas: Big Thicket National Preserve (Hardin, Liberty, and Tyler Counties), Sandyland Preserve (Hardin Co.).

Several key donations and exchanges of ants from western states, Louisiana and Tennessee have increased the holdings of the Mississippi Entomological Museum (MEM) collection. Numerous specimens collected during the year were pinned, labeled, identified, and added to the collection. The donation of ants in vials of alcohol was sorted and identified. Identifications of ants were made for 10 researchers. Current projects include publishing up to date lists of the ants of Tennessee, Mississippi, and Big Thicket National Preserve, TX; examining trap samples from Kentucky to document ants of that state; a collaborative project studying the use of artificial wooden nests in the field in various southeastern forested sites to study ant nest densities, colony structure, spatial partitioning, and efficacy of the artificial nest design; a collaborative project studying colony structure, environmental factors limiting nesting sites, and spatial partitioning of cavity dwelling ant species in nuts of eastern U.S. forest floors; a study of the worldwide distribution of Strumigenys margaritae; development of identification resources for the Solenopsis molesta group in the Southeast; and continued monitoring for the hairy crazy ant along the Gulf Coast. As a result of recent surveys, several new state records in GA, MS, TN, and TX were discovered. Discoveries of two new species of Nylanderia and three new species of Polyergus collected by MEM staff have been described and will be included in upcoming revisions of these groups. As a result of collaborative work with researchers from LSU, a new exotic dacetine ant, Strumigenys epinotalis, was discovered for the U.S. and the novel use of modified arboreal pitfall traps used to collect them was described. The spread of the exotic stinging ant Gnamptogenys triangularis from South America to the southern U.S. was studied and results were published. The worldwide geographic spread of the exotic S. silvestrii was documented and a publication is in press. Collections of fire ants and hairy crazy ants were made for DNA studies by researchers from Mississippi State University (MSU). Surveys along the MS gulf coast have shown that the hairy crazy ant (Nylanderia sp. near pubens) has extended its distribution to new localities in the region. The exotic stinging ant Pseudomyrmex gracilis was discovered to occur in southern Alabama for the first time (Mobile Co.), and this species has now been found in four southern counties in MS (Hancock, Harrison, Jackson, and Pearl River). Camponotus tortuganus, a structural pest species of carpenter ant previously known only from southern FL, was discovered in southern MS. The website "Ants of the Southeastern United States" was revised to update recent nomenclatorial changes in the Amblyoponinae, Myrmicinae (Dacetini), and Ponerinae groups. Several new faunal studies were added to the site, numerous species pages were updated, and keys were updated to reflect nomenclatorial changes. .

Outreach activities included examination of fire ants with a portable scanning electron microscope for visiting school groups and the 4-H Entomology Bug Camps at Mississippi State University. Media interviews regarding Hairy Crazy Ants (Nylanderia) were made for Associated Press and carried by many national and international newspapers, Fox News and CBS News (national), local television news, live radio in Mississippi and Australia, and Mississippi Landmark magazine.

II. Genomic and physiological studies of select exotic ants in the southern United States. Microsatellite alleles for four gene loci were compared across S. invicta, S. richteri (red and black imported fire ant) and their hybrid. Particularly for regions with high occurrence of hybrids, at least one of these alleles in the Sol49 locus is highly indicative of either the hybrid (>85% present) or the S. richteri (100% present) form. This marker is absent in the red imported fire ant (S. invicta). The extremes in prevalence of this and other markers will aid in using genetic assays to more readily identify individual ants tospecies or hybrid form. Isolating South American source of black imported fire ant (Solenopsis richteri) in the U.S.: S. richteri from five TN counties have been sequenced for a 414 base pair mtDNA gene fragment. Enzyme digests were used on a larger sample of S. richteri from TN and MS. The sequence and digest data exactly match a haplotype reported from ants collected in Arroio dos Ratos, Brazil. Knowledge of the genetic source of this species provides amore refined basis for the application for biological control measures. Gene candidates are presently being evaluated for Nylanderia pubens (hairy, or Caribbean, crazy ant) population studies. Hairy crazy ant sequences have been generated for TX, FL, MS and Paraguay populations. Hairy crazy ant cold tolerance study: We collected hairy crazy ants from a Jackson Co., MS, population first noted in 2010. The super cooling point of ants was measured at the Grand Bay National Estuarine Research Reserve. Analysis of the data is ongoing. Diagnostic genetic assays were performed to provide colony social form and species/hybrid status for both departmental and USDA-ARS researchers.

III. Ultrastructure of chemoreceptors on mouthparts of Solenopsis and Nylanderia Research addressed the lack of information on the cuticular sensory receptors of the mouthparts of the imported fire ants, Solenopsis invicta, S. richteri, and the hairy crazy ant Nylanderia pubens. Sensilla of the labial and maxillary palpi of workers of these invasive ants were studied with scanning electron microscopy. Solenopsis workers have labial palpi with two segments, with the apical segment bearing three, smooth trichoid sensilla and a peg-like sensillum; all sensilla are porous indicating a chemomechanical function. Lengths of the trichoid sensilla differ between S. invicta and S. richteri and between major and minor workers of the same species. The maxillary palpi of the two Solenopsis species are similar in being one segmented and having a single porous trichoid sensilla in both major and minor workers. Nylanderia pubens, which lacks major and minor casts, has labial palpi with four segments covered with long microtrichial processes with unknown function. This species is similar to Solenopsis workers in having three trichoid sensilla and a peg sensillum, but the trichoid sensilla are grooved. The maxillary palpi have five segments with the apical segment having three, grooved trichoid sensilla, instead of one smooth sensillum as in Solenopsis species.


Last Modified: 7/25/2014
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