Fire Ant Trails:
News from the Texas Imported Fire Ant Research & Management Plan

September 1999 Vol. 3 No. 1

Fire Ant Awareness Week, September 12 - 18, 1999, Features a New Videotaped Educational Program

By now, everyone should know that the second week in September is Fire Ant Awareness Week in Texas. Each County office and Extension staff will be receiving a recently produced videotape program called,

"The Texas Imported Research and Management Fire Ant Project" (VHS#2321). This 18 minute videotape was developed in collaboration with the Hutchings Media Group International. The program introduces the viewer to the red imported fire ant, discusses the Fire Ant Research & Management Plan and current research, fire ant control options and promotes the concept of managing these ants on a community-wide basis.

Funding for the production of this video tape was provided, in part, by the following companies:

We wish to thank these groups for supporting the Texas Imported Fire Ant Project and becoming part of the "Team" for tackling imported fire ants!

The video tape is being distributed to all Texas counties. Additionally, copies can be checked out from Extension's Audio Visual Library by ordering VHS#2231

Additional support materials for Fire Ant Awareness Week have been prepared by Agricultural Communications' Lynette James, Edith Chenault and Jerrold Summerlin. Copies are available and all of these materials can be downloaded from the web site, http://fireant.tamu.edu

If you or your organization wishes to support the Texas Imported Fire Ant Research & Management Plan and join the "Team", hit the logo on our web site home page and select "Make a Contribution"

Citrus Oils and D-Limonine as Fire Ant Insecticide - prepared by Bastiaan M. Drees, Texas Imported Director, Texas Imported Fire Ant Project

A new product was launched this summer (August 23, 1999) in the Houston area:

CITREX™ Fire Ant Killer. This product contains 78.2 percent d-limonine, which is a botanical or plant-derived insecticide extracted from citrus peels. Citrus peels contain several compounds known to have insecticidal activity: d-limonine and linalool. Citrus extracts have been reported to be toxic to fire ants (Ellis & Bradley 1996), but until now have not been formulated as insecticides and registered for use by the Environmental Protection Agency (EPA).

The Texas Agricultural Extension Service evaluated an earlier, experimental formulation of d-limonine as a mound drench in 1995. The report can be found on the web site, http://fireant.tamu.edu, under "Research", "Applied Research", "Individual Mound Treatments", and is entitled, "Evaluation of D-Limonine as an Individual Red Imported Fire Ant Mound Treatment, 1995" by C. L. Barr. The formulation tested provided about 80 percent elimination of ant colonies in treated mounds. The new product contains a new emulsifying agent, but the active ingredient is still the same. However, it has not been formally evaluated.

CITREX™ Fire Ant Killer (EPA Reg. No. 72244-1-72440; EPA Est. No. 72440-TX-01) is manufactured by Envirosafe Labs, LLC (210 North Loop 336 East, Conroe, TX 77301; www.envirosafelabs.com). It is applied as a mound drench: Do not disturb mound prior to applying mixture. Mix with water at a rate of 8 fl. oz. per gallon of water to undisturbed ant mounds making sure to completely saturate each mound treated. Although not stated on the product label, promotional/supplemental information from EnviroSafe Labs, LLC promotes use of this product in "outdoor areas including gardens, ornamental turf, golf courses, school grounds and croplands.

Source and mode of action: Crude citrus oils and the refined compounds d-limonine and linalool are extracted from orange and other citrus fruit peels. D-limonine, a terpene, constitutes about 90 percent of crude citrus oil, and is purified from the oil by steam distillation. The mode of action of d-limonine in insects are not fully understood. D-limonine is thought to cause an increase in the spontaneous activity of sensory nerves. The heightened activity sends spurious information to motor nerves and results in twitching, lack of coordination, and convulsions. The central nervous system may also be affected, resulting in additional stimulation of motor nerves. Massive over stimulation of motor nerves leads to rapid knockdown paralysis. However, adult fleas and other insects may recover from knockdown. Crude citrus peel oils and products prepared with crude oils may be more toxic to animals than products containing purified d-limonine or linalool (Weinzeri & Henn 1989).

Both d-limonine and linalool were granted GRAS (Generally Regarded as Safe) status by the United States Food and Drug Administration in 1965, and are used extensively as flavorings and scents in foods, cosmetics, soaps, and perfumes. Both compounds are considered safe when used for these purposes because they have low oral and dermal toxicities (Table 1). At higher concentrations, however, d-limonine and linalool are physiologically active and may be irritating or toxic to mammals. Exposure to citrus oils may cause some animals to experience tremors and salivation, although generally not harmful to humans.

Table 1. Toxicity (LD50) values for active ingredients (milligram/killogram of body weight): Higher values are less toxic.

Ingredient Oral   Dermal Signal word
d-limonine >5,000  – CAUTION  
linalool 2,440-3,180 3,578-8,374 CAUTION
pyrethrins1,200-1,500 > 1,800 CAUTION
rotenone60-1,500* 940-3,000 CAUTION
nicotine 50-60 50 DANGER
*toxicity varies greatly depending on type of solvent used as a carrier

Although d-limonine has been used in insecticide products for other pests such as fleas, CITREX is the first product registered to control imported fire ants. Another product is available for killing and repelling ants:

Concern® Citrus Home Pest Control™ (EPA Est. No. 55179 EPA Reg. No. 61887-1-50932) produced by Necessary Organics, Inc., One Nature's Way, New Castle, VA 24127-0305; www.concerngarden.com; (CAUTION) contains 5.8 percent d-limoninein a ready-to-use hand pump spray bottle. It can be applied to pet bedding to control fleas, or indoors to spray ants and other insects directly or applied to cracks and crevices in kitchens and pantries, under cabinets and appliances, anywhere insects hide. Treatments are claimed to keep killing and repelling for weeks. Outdoors, the product can be sprayed around perimeter of home to make barrier of protection or applied to doorways, window frames, cracks, anywhere insects can enter, saturating areas of trails or nests.

In 1997, a fire ant mound drench product was available in parts of Texas containing 30 percent orange oil and 70 percent liquid compost: Fire Ant Control produced by Garden-Ville Fertilizer Co. (7561 E. Evans Rd., San Antonio, TX. 78266; phone: 210/ 651-6115). The user was directed to apply the drench after mixing 4 to 6 ounces product per gallon of water. A new formulation of this product is currently being evaluated by Extension Agents - IPM (Fire Ant Project) and federal registration is being sought. The initial formulation was made available as a home recipe (see the web site, http://fireant.tamu.edu under "materials" and "fact sheets" for FAPFS#012).

Citations:
Ellis, B. W. and F. M. Bradley (eds.) 1996. The Organic Gardener's Handbook of Natural Insect and Disease Control. Rodale Press, Emmaus, PA. 534 pp.

Henn, T. and R. Weinzeri. 1989. Botanical Insecticides and Insecticidal Soaps. Circular 1296. Cooperative Extension Service. University of Illinois, Urbana-Champaign

Texas Gets Fire Ant Insecticide Product Named For the State!
Accompanying the May Issue (Issue II, 1999) of DowAgroSciences Active Info, an insect announced the availability of a new product containing chlorpyrifos called Knockout® Brand Texas Lone Star™ Fire Ant Killer for use in ornamental and recreational turf! Note that this product is not in any way associated with the Texas Imported Fire Ant Research & Management Project...

Texas County Future Forum (TCFF) Identifies Fire Ants as Top Issues
 Bowie, Colorado, Cooke, Coryell, Hamilton, Liberty and Orange Counties have determined that imported fire ants and their management is a major issue of concern in their counties.

Fire Ant Project Web Site Wins Awards
 In July, Agricultural Communications has won a number of awards:

Mary Porter reported that The Dallas Morning News included the fire ant web site in an article in Friday's printed edition in the gardening section. The link to the online article is:

http://www.dallasmorningnews.com/lifestyles/0702hg2gardenweb.htm

Congratulations to Lynette James and Edith Chenault for all the hard work they have done to make this a great web site!

Audio Clips and New Information on the Fire Ant Web Site!
The three "hit singles" written about fire ants are now featured along with an actual recording of a red imported fire ant "stridulating." Like other ant species, imported fire ants communicate by making squeaking sounds from a stridulatory organ on the ant's body, consisting of a washboard-like set of ridges and a scraper (R. Hickling, U. Mississippi)! No cheating by listening to this recording provided by Dr. S. Bradleigh Vinson when practicing for this year's fire ant calling contest held annually with the Marshall Fire Ant Festival!

The fire ant "hits" include:

New USDA Publication
A new publication, Imported Fire Ant: Quarantine Treatments for Nursery Stock and Other Regulated Articles" (Animal and Plant Health Inspection Service Program Aid No. 1653, June 1999) is available. The State Plant Health Director of the USDA-APHIS in Texas is located at 903 San Jacinto Blvd., Suite 270, Austin, Texas 78701-2450 (512/916-5241).

New Publications

Fact sheets are available as copy-ready copies, print-on-demand copies, or can be downloaded from the fire ant web site. If bulk copies are required, plan ahead and contact Anna Kjolen, Administrative Assistant for the Texas Fire Ant Project (a-kjolen@tamu.edu or phone 409/845-5878).

Check Out These Magazine Articles:

 

>Prepared by: >Bastiaan "Bart" M. Drees,>
Director, Texas Imported Fire Ant Project
>Department of Entomology>
412 Minnie Belle Heep Bldg.>
Texas A&M University>
College Station, Texas 77843-2475>
409/845-5878; FAX: 409/845-7029>
b-drees@tamu.edu>
http://fireant.tamu.edu

The information given herein is for educational purposes only. Reference to commercial products or trade names is made with the understanding that no discrimination is intended and no endorsement by the Texas Agricultural Extension Service or the Texas Agricultural Experiment Station is implied.

>Educational programs conducted by the Texas Agricultural Extension Service serve people of all ages regardless of socioeconomic level, race, color, sex, religion, disability or national origin.