ELIMINATION OF SUBTERRANEAN TERMITE POPULATIONS FROM THE STATUE OF LIBERTY NATIONAL MONUMENT USING A BAIT MATRIX CONTAINING AN INSECT GROWTH REGULATOR, HEXAFLUMURON
NAN-YAO SU, JAMEY D. THOMAS, & RUDOLF H. SCHEFFRAHN
After consuming a total of 1.8 g hexaflumuron, all four clusters of termite activity were eliminated from the Statue of Liberty National Monument (see table 1). A conventional soil treatment of trenching and rodding the monument foundation would have applied >50 kg of insecticide (active ingredient), and such a soil treatment probably would have only excluded, instead of eliminating, soil-borne termites from the structure. The baiting program required considerably less insecticide because baits were used only when and where they were needed and because termites themselves delivered hexaflumuron to nestmates. As shown in this study, however, baiting is also time- and labor-consuming. Time required for elimination ranged from three months (BOL) to 11 months (SAL), possibly due to the differences in population size of the subterranean termite colonies. Because hexaflumuron is an insect growth regulator that affects termite molting, and termites probably do not molt often when temperatures are low, termite populations that survived the baiting program before the onset of cold weather (SAL and EXT) tend to require additional bait application before elimination (see fig. 4).
After the elimination of all detectable termite populations, 77 Sentricon stations were placed in soil (see fig. 2, S) at 5 m intervals surrounding the exterior wall foundation of the monument in October 1997. The stations are monitored quarterly by volunteer pest control firms and Dow AgroSciences personnel. Because the monument is on an island, as long as precautions are taken to avoid shipment of infested materials, further immigration by termites is unlikely. It is probable that some alates that swarmed in 1994–96 may have successfully initiated small colonies on the island. Such incipient colonies may have escaped our survey. As these small populations grow, it is expected that the ongoing monitoring program with the Sentricon stations will detect termite activity and subsequently eliminate it by additional baiting before substantial damage is done.
We are grateful to A1 Farrugio (Statue of Liberty National Monument, National Park Service), Paul M. Ban (University of Florida) and James R. Lofton (Dow AgroSciences) for technical assistance, and Joan Perrier (University of Florida) for figure illustrations. We also thank to Robin Giblin-Davis (University of Florida) and Mark Gilberg (National Center for Preservation Technology and Training, National Park Service) for reviewing this manuscript. Partial funding for this project was provided by NCPTT, National Park Service, Department of the Interior under the grant agreement No. MT-0424-5-NC-023. Additional funding was provided by the Statue of Liberty–Ellis Island Foundation, Inc. (This article is Florida Agricultural Experiment Station Journal Series No. R-06117).