Insecticidal Control of the Red Imported Fire Ant,
Solenopsis invicta at Chamizal National Memorial
Fire Ant Laboratory, Department of Biological Sciences,
The University of Texas at El Paso, TX 79968
This experimental project is being conducted to evaluate the impact of insecticide on the Red Imported Fire Ant, Solenopsis Invicta Buren. AMDROâ and Logicâ insecticides were used in this project. The impact of AMDROâ and Logicâ on S. invicta was determined based on change of colony size, or if S. Invicta relocated somewhere else. The Chamizal National Memorial in El Paso, Texas was sampled and the greatest concentration of S. invicta was found in the Bowl area. The Bowl area was treated using the insecticides. Results showed that the number of nests had decreased significantly.
The red imported fire ant, S. invicta Buren, has greatly spread throughout the southern United States. The origin of S. invicta is in South America in the Pantanal area of Mato Grosso, Brazil which is a large swampy grassland with huge trees which are flooded naturally every year (Wojcik, 1983). Solenopsis invicta has infested the southern United States at a rapid rate possibly because there are many areas that are similar to their natural environment. Sometime between 1933 and 1945 this red imported fire ant was introduced into the United States in the area of the Mobile, Alabama port (Buren, et al, 1974). According to Lofgren, et al, (1975), S. invicta had invaded nine states from the Carolinas to Texas by 1980.
After a survey conducted in the summer of 1998 by the Fire Ant Laboratory at the University of Texas at El Paso, S. invicta was found at the Chamizal National Memorial in El Paso, Texas. The objective of this project is to evaluate the impact of insecticides on the Red Imported Fire Ant, S. invicta. It was hypothesized that the spread of insecticides in the Bowl area of the Chamizal National Memorial will have an observable decline of S. invicta nests. The null hypothesis for this project states that there will not be an observable decline of treated S. invicta nests in the Bowl area of the Chamizal National Memorial.
METHODS AND MATERIALS
The study site for this experiment is at Chamizal National Memorial in the Bowl area where weekly concerts of Music under the Stars are held every Sunday during the summer. The bowl area is approximately 1.62 hectares, it is oval shaped and has a depression in the center. An outdoor stage is located at the southern end of the bowl and trees run along the rim. The Bowl area was sampled using surface baits which consisted of one ounce Dixie cups with lids and a piece of Tuna Flavored Tender Vittle Cat Food. Five transects were done running across the Bowl area, each transect consisted of 15 surface baits which were placed every ten meters. The surface baits were used to collect surface ants that were foraging for food and to determine which nest were S. invicta. Then S. invicta nests were counted and plotted on a map.
In the beginning of October 1998, there were 76 nests active with S. invicta. Experiments were conducted using Logicâ (fenoxycarb) and combinations of AMDROâ (hydramethylon)/ Logicâ . In May 1999, before Memorial Day, a wide broadcast was done using Logicâ . After that each mound was treated individually using combinations of AMDROâ / Logicâ . It was believed that Mondays were a good time to treat especially after the concert on Sunday, since people would leave crumbs of food, scattered all over the grounds.
RESULTS AND CONCLUSION
The results did reveal significant reductions of S. invicta nests in the Bowl Area of the Chamizal National Memorial. Maps 1 and 2 reveals show the difference in the number of S. invicta ant mounds. As of today, there are approximately 21 S. invicta nest present and only five nests still exist out of the 76 nests from October, 1998. This means that it is suspected that these nests relocated not too far from their original location. Although the insecticides appear to be working, the colonies maybe regularly migrating within the Bowl area of the Chamizal National Memorial. Colonies are repeatedly migrating to other sites and can often redevelop quickly several hundred feet away (Drees, 1998). Both types of insecticides, AMDROâ and Logicâ , can be used as effective insecticides in the control of Red Imported Fire Ant nests.
Insecticides AMDROâ and Logicâ should be continued to eliminate S. invicta nests from the Chamizal National Memorial as well as other areas of El Paso in order to prevent them from increasing. Therefore, based on the results of this project we can reject the null hypothesis which states that the insecticides AMDROâ and Logicâ will not eradicate (or reduce) Red Imported Fire Ant mounds from the Bowl area at the Chamizal National Memorial. I suggest that further research should be done in order to see if S. invicta could in any way build a resistance to the insecticides. I believe that there should also be a continuating spread of insecticides to see if the S. invicta problem can be completely eradicated from the Chamizal National Memorial.
Buren, William F., George E. Allen, Willard H. Whitcomb, Frances E. Lennartz, and Roger N. Williams. 1974. Zoogeography of the Imported Fire Ants. Journal of the New York Entomological Society 2:113-123.
Drees, Bastiaan M., Charles L. Barr, S. Bradleigh Vinson, Roger E. Gold, Michael E. Merchant and David Kostroun. 1998. Managing Red Imported Fire Ants in Urban Areas. Texas Agricultural Extension Service. College Station, Texas.
Lofgren, C.S., W.A. Banks, and B.M. Glancey.1975. Biology and Control of Imported Fire Ants. Annual Review of Entomology 20:1-18.
Wojcik, Daniel P. 1983. Comparison of the Ecology of Red Imported Fire Ants in North and South America. The Florida Entomologists 1:101-111.
I would like to thank Dr. William P. Mackay, Dr. Raphael Cabeza, Dr. Jerry Johnson, Dominic Lannutti, Matthew McMillan, Mario Chavez, Hilda Taylor, Isidra Moreno, Cindy Morales, Cynthia Altamirano, Daniel Padilla, Jerome T. Flood, Jesus Bravo, the Desert Ecology Laboratory at UTEP, the Chamizal National Memorial staff, and the Bridges to the Future Program for their help and support.
Approximately 70 Nests Before Treatment
|Approximately 21 Nests After Treatment|
Denotes Solenopsis invicta nests
Denotes trees found in Bowl area?