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A System for Elimination of

Subterranean Termite ColoniesNan-Yao Su and Rudolf H. Scheffrahn

University of Florida, Ft. Lauderdale Research and Education Center

3205 College Avenue

Ft. Lauderdale, FL 33314

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Of the approximately $1.5 billion spent annually for termite control in the U.S.,subterranean termites account for an 80% share. Triple mark-recapture programs using dye

markers such as Sudan Red 7B Figure 1 revealed that a single subterranean termitecolony may contain millions of foragers and may forage a distance of up to 300 ft (Su andScheffrahn 1988, Grace et al. 1989, Su et al. 1993). A large subterranean termite colony,therefore, may inhabit large areas of soil beneath an infested home Figure 2A .

Conventional soil termiticides have been used for the last four decades to provide achemical barrier for the exclusion of soil-borne termites from a structure Figure 2B .

Typically, 100 - 200 gal. of liquid termiticide (8 - 17 lb. active ingredient @ 1%concentration) are applied in the soil beneath and surrounding an infested home (NPCA1985). The vast proportion of subterranean termites, however, are not affected by such soiltermiticide treatment Figure 2B . These termites often find their way back into the

structure, causing costly re-treatment (Su and Scheffrahn 1988).

Population studies for field colonies of subterranean termites indicated that wooden stakesplaced near a large colony of these cryptic insects are eventually attacked by termites.Slow-acting and non-repellent toxicants may be incorporated into such food sources toaffect the vast population of the subterranean termite colony (Su et al.1982) Figure 2C .

Through an extensive laboratory screening program (Su and Scheffrahn 1993), wediscovered that a chitin synthesis inhibitor, hexaflumuron, interfered with the moltingprocess of both the Formosan subterranean termite, Coptotermes formosanus, and theeastern subterranean termite, Reticulitermes flavipes Figure 3 . A baiting procedure that

incorporated a matrix containing hexaflumuron was evaluated against field colonies of theFormosan and eastern subterranean termites (Su 1994a). Wooden stakes were first driveninto soil to detect the presence of termites. Bait tubes were placed in the soil where termites

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were detected. The results demonstrated that approximately 4 - 1,500 mg (less than 1/20oz.) of hexaflumuron was needed for 90 - 100% reduction of field populations containing0.5 - 2.8 million eastern subterranean termites per colony Figure 4 , and 1.0 - 2.4 million Formosan subterranean termites per colony Figure 5 . Elimination of colony populationscreated a zone of termite-free soil surrounding a home for several years (Su 1994b).

Following the success of the initial field trials, a prototype monitoring/baiting station wasdesigned for commercial application Figure 6 . The station containing the monitoring

device is first installed in soil surrounding a home Figure 7A . When termites are found in the station Figure 7B , the monitoring device is replaced with a tubecontaining bait laced with a minute amount of hexaflumuron Figure 7C . Termites collected from the monitoring device are dislodged into an empty space on the top of thetube, called the "recruiter's chamber." Figures 7C, D

Termites placed in the recruiter's chamber have to feed their way out of the bait to reunitewith nestmates Figures 8A, B . Left behind in the bait are their species- and

colony-specific odors Figure 8C . One of such chemicals is the trail-following

pheromone excreted from the sternal gland Figure 9 , which guides nestmates to the

bait. This self-recruitment procedure enhances bait uptake by termites (Su 1994a).Hexaflumuron kills insects only when they molt every 1 - 2 months. During this period, thebait is thoroughly distributed throughout the colony populations. The monitoring/baitingsystem is currently commercialized under the Sentricon® brand name by DowElanco(Indianapolis, IN), who invented and owns the proprietary rights to hexaflumuron. Fieldtrials using the system typically require less than one gram (0.04 oz.) of hexaflumuron toeliminate field populations of several million termites (Su et al. 1995) Figure 10 .

References Cited

Grace, J. K., A. Abdallay and K. R. Farr. 1989. Eastern subterranean termite (Isoptera:Rhino-termitidae) foraging territories and populations in Toronto. Can. Entomol. 121:551-556.

NPCA (National Pest Control Association). 1985. Approved reference procedures forsubterranean termite control. NPCA Inc., Dunn Loring, VA.

Su, N.-Y. 1994a. Field evaluation of a hexaflumuron bait or population suppression ofsubterranean termites (Isoptera: Rhinotermitidae). J. Econ. Entomol. 87: 389-397.

Su, N.-Y. 1994b. The termite bait age dawns. Pest Control 62: 36-38.

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Su, N.-Y. and R. H. Scheffrahn. 1988. Foraging population and territory of the Formosansubterranean termite (Isoptera: Rhinotermitidae) in an urban environment. Sociobiology14: 353-359.

Su, N.-Y. and R. H. Scheffrahn. 1993. Laboratory evaluation of two chitin synthesisinhibitors, hexaflumuron and diflubenzuron, as bait toxicants against Formosan and easternsubterranean termites (Isoptera: Rhinotermitidae). J. Econ. Entomol. 86: 1453-1457.

Su, N.-Y., M. Tamashiro, J. R. Yates and M. I. Haverty. 1982. Effects of behavior on the evaluation of insecticides for prevention of or remedial control of the Formosansubterranean termite. J. Econ. Entomol. 75: 188-193.

Su, N.-Y., P. M. Ban and R. H. Scheffrahn. 1993. Foraging populations and territories ofthe eastern subterranean termite (Isoptera: Rhinotermitidae) in southeastern Florida.Environ. Entomol. 22: 1113-1117.

Su, N.-Y., E. M. Thoms, P. M. Ban and R. H. Scheffrahn. 1995. A monitoring/baiting station to detect and eliminate foraging populations of subterranean termites (Isoptera:Rhinotermitidae) near structures. J. Econ. Entomol. 88: 932-936.