Subterranean Termites Feeding on CSI Baits for a Short Duration Still Results in Colony Elimination

Termite baits using chitin synthesis inhibitors can protect structures from subterranean termite damage by eliminating colonies. One of the potential shortcomings of baits is that termites may have to feed extensively on a bait station for the colony to be eliminated. If disturbances occur during this critical feeding time, termites may abandon the site, which could prevent colony elimination. We exposed whole laboratory colonies of Coptotermes gestroi (Wasmann) containing an average of 59,000 termites to 0.5% noviflumuron baits, from 1 to 10 d, to simulate a temporary access to the bait as a result of disturbances. Our results show that colonies which fed for a single day and consumed as little as 1.1 g of bait matrix (=5.5 mg noviflumuron) were eliminated within 90 d. This study indicates that only a fraction of the bait matrix is necessary for elimination of large laboratory colonies, and that hypothetical disturbance reducing the access to a bait station would likely have little impact on the effect of the bait. Within 1 d, colonies had already acquired a lethal dose, which is shared by trophallaxis to all individuals of the colony, and colonies inevitably died despite short exposure to noviflumuron. It is estimated that if a field mature colony of 1 million individuals consumes more than 18.6 g of bait (=93 mg noviflumuron) in a relatively short period, it would already have acquired a colony-wide lethal dose and reached a point of no-return for colony elimination.