FATE OF SUBTERRANEAN TERMITE COLONIES (ISOPTERA) AFTER BAIT APPLICATIONS - AN UPDATE AND REVIEW

Populations of 6 colonies of the Formosan subterranean termite, Coptot ermes formosanus Shiraki, were significantly reduced but survived afte r 12-mo baiting using metabolic inhibitors such as A-9248 (diiodomethy l para-tolyl sulfone) or sulfluramid. These survived colonies recovere d within several years and caused additional structural damage to the nearby buildings. Nine colonies (6 C. formosanus and 3 Reticulitermes flavipes (Kollar)) were eliminated after 2 - 9 mo baiting using the ch itin synthesis inhibitor, hexaflumuron. Colony elimination generally c reated zones of termite-free soil that lasted for several years, excep t for one colony whose territory was invaded by a new C. formosanus co lony 9 mo after the baiting. The presence of neighboring colony popula tions are evident in 3 sites but these neighboring colonies did not ta ke over territories of eliminated colonies. Two additional colonies (o ne each of R. flavipes and C. formosanus) were intentionally left aliv e after partially suppression using hexaflumuron baits. One colony (R. flavipes) slowly declined and eventually collapsed 4 yrs after the ba iting, while the other colony (C. formosanus) recovered. Results of th is study demonstrated the advantages of colony elimination in providin g long-term protection of structures from subterranean termites. Elimi nation of colony populations was achieved only when the chitin synthes is inhibitor, hexaflumuron, was used. Baits containing metabolic inhib itors such as A-9248 or sulfluramid only partially suppressed the colo ny populations even after the monthly placement of baits for 12-mo. El imination of the vast populations of subterranean termite requires tha t the toxicant must be (1) slow-acting (2) non-deterrent, (3) must not cause adverse effects when ingested at sublethal dose levels, and (4) its lethal time must be dose-independent.