EXXANT RESEARCH

SUMMARY OF FINAL REPORT
Effectiveness of exxantTM for the control of
individual red imported fire ant colonies

Charles L. Barr Extension Program Specialist - Fire Ant  Project
Rody L. Best  Extension Assistant, Fire Ant Project
    The following trial tested the effectiveness of the product exxantTM Fire Ant Killer, distributed by Lang Laboratories, as an individual mound treatment for the control of red imported fire ants (Soenopsis Invicta Buren)

    The test was designed to test not only the effectiveness of the product on treated mounds, but also to detect colony movement, shattering, and/or appearance of "new" mounds within plot.

    The test was established near one end of Coulter Field, the municipal airport serving Bryan, Texas. A strip of land 30 ft. wide by indeterminate length constituted the test area. Mounds were identified using surveyor flags of differing colors until enough active mounds were marked to total 200 mounds. The mound areas were then divided into plots containing 4 replications of 10 mounds each per treatment solution.

    Solutions were mixed in watering buckets and applied to each mound until the mound filled and no more solution could be applied without excessive runoff. The standard Drench Treatment was mixed and applied similarly, but one gallon was applied to each mound, regardless of runoff, as per label directions.

    Results within Table 3 indicate that at the conclusion of the 33 day test, both the 1 oz. and 2 oz. concentrations were found to be as effective as the Standard in controlling the total active mound population.

    exxantTM took about one week to reach maximum suppression in treated mounds and was rate-dependent with the 2 oz, rate working the fastest. Given the rate responses seen, it is possible that a higher concentration solution of exxantTM would produce faster, more thorough colony elimination. With the concentrations tested, there was no sign of phytotoxicity.

    In summary, of the three rates tested the high rate of exxantTM 2.0 oz. per gallon applied to runoff, gave the best control of the fire ant mounds that were treated and a comparable control to that of the standard treatment. It took between 3 and 7 days for the 2 oz. treatment to reach maximum mound suppression. Results suggest that treatment with exxantTM may result in short-term colony movement and/or shattering before eventual elimination. This outcome was duplicated by the standard drench treatment, as well. In addition, weather and the actual site may have played a part in what appears to be substantial re-invasion of the plots by the end of the test. Considerable rain was received at the site shortly before the final evaluation after a three-week dry spell, which often leads to fire ant colony movement. Also, this particular site is known for the ants' tendency to abandon mounds and rebuild frequently. The very high density (600 mounds per acre) likely increased re-invasion as well.

    exxantTM is a non-toxic, non-poisonous permanent solution that does not involve any of the safety and environmental concerns that the standard drench requires for its use.
    Treatment Included:
    1. Untreated Included
    2. exxantTM 1/2 oz. per gallon of water
    3. exxantTM 1 oz. per gallon of water
    4. exxantTM 2 oz. per gallon of water
    5. Standard Drench Product, 4 tablespoons (2 oz.) per gallon of water

    Standard Drench (diatomaceous earth, 0.1% Pyrethrin and piperonyl butoxide) was included as a standard drench-type treatment as it has consistently shown near 100% control of treated mounds with little satellite mound formation, in previous tests.

Table 1. Mean number of active marked mounds per plot of 10 treated
TREATMENT
DAY 7
DAY 14
DAY 33
UNTREATED 8.50 8.75 8.25
exxantTM-1/2 oz. 2.25 0.50 2.00
exxantTM - 1.0 oz. 1.00 1.25 1.50
exxantTM - 2.0 oz. 0.50 0.25 0.25
STANDARD DRENCH 0.25 0.25 0.75

Results within Table 1 indicate that at day 14, exxantTM tested just as effective as the standard treatment and at the conclusion of the test, exxantTM tested slightly higher than the standard in eliminating existing mounds. Results indicate 97.5% effectiveness with only one treatment.


Table 2. Mean number of active "new" mounds per plot
TREATMENT
DAY 14
DAY 33
UNTREATED 2.25 3.00
exxantTM - 1/2 oz. 5.00 6.00
exxantTM - 1.0 oz. 2.00 5.50
exxantTM - 2.0 oz. 4.76 6.75
STANDARD DRENCH 2.25 5.75

Results within Table 2 indicate that at the conclusion of the 33 day test exxantTM proved to be just as effective as the standard drench in the prevention of new mounds.


Table 3. Mean number of total active per plot (treated + new)
TREATMENT
DAY 14
DAY 33
UNTREATED 11.00 11.25
exxantTM - 1/2 oz. 5.50 8.00
exxantTM - 1.0 oz. 3.25 7.00
exxantTM - 2.0 oz. 5.00 7.00
STANDARD DRENCH 2.50 6.50


EVALUATION OF AANKILL4 AS AN  INDIVIDUAL MOUND TREATMENT PRIOR TO NAME CHANGE IN 1999 TO exxantTM
For Control of Red Imported Fire Ants

W.A. Banks, U.S.A. Department of Agriculture
Agricultural Research Service Medical and Veterinary
Entomology Research Laboratory
P.O. Box 14565, Gainesville, Florida 32604
    Aankill 44, supplied to us by Lang Laboratories, Inc., was evaluated as an individual mound treatment for fire ants. Tests were conducted according to the attached protocol. For this particular test, plot size was 0.2 ha; each mound was drenched twice with 5 0z. of exxantTM per 5 gallons of water. The initial treatment was made on August 3rd and the second treatment on August 13th. A total of 15 mounds in the 0.2 ha plot were treated each time. Effectiveness of the treatment was evaluated on seven mounds in the smaller 1.0 ha circle in the center of the plot.

    Evaluations were made on August 30th and September 27th (about 4 and 8 weeks respectively after initial treatment). The following tables show the results of the pre and post treatment counts on the treatment plot and untreated controls. After four weeks the treatment had completely eliminated on 1 colony, however, all the surviving colonies had been drastically reduced in size as evidenced by the 92% reduction in the population index. By 8 weeks, only one colony remained active and it contained only worker brood and only a few hundred workers.

"Careful survey of the plot indicated that the colonies were in fact killed and had not simply relocated."

 
TABLE 1. Effectiveness of exxantTM as an Individual Mound Treatment
PRETREATMENT 4-WEEK POST-TREATMENT PERCENTAGE/CHANGE
Replicate No. Nests Pop'n Index No. Nests Pop'n Index No. Nests Pop'n Index

exxantTM
1 7 150 6 12 -14.3% -92.0%

CONTROL
1 6 140 8 150 +33.3% +7.1%
2 6 140 8 155 +33.3% +10.7%
3 6 150 7 165 +16.7 +10.0%
TOTALS 18 430 23 470 +26.4% +9.3%
 

 
TABLE 2. Effectiveness of exxantTM as an Individual Mound Treatment
PRETREATMENT 4-WEEK POST-TREATMENT PERCENTAGE/CHANGE
Replicate No. Nests Pop'n Index No. Nests Pop'n Index No. Nests Pop'n Index

exxantTM
1 7 150 1 2 -85.7% -98.7%

CONTROL
1 6 140 7 138 +16.7% +1.4%
2 6 140 8 164 +33.3% +17.1%
3 6 150 7 150 +16.7 +0.0%
TOTALS 18 430 22 452 +22.2% +5.1%
 

Notes from USDA Report
    Pop'n Index - Population Index - Value assigned to each mound based on estimated number of worker ants present.

    Control - Mounds in control area were treated with water only at same concentration as drench.

    Treatment - Mounds in treated area were treated with one gallon of exxantTM drench applied to mounds less than 8 inches in diameter and 2 gallons to mounds more than 8  inches in diameter.