Molting site fidelity accounts for colony elimination of the Formosan subterranean termites (Isoptera: Rhinotermitidae) by chitin synthesis inhibitor baits

Abstract

Site fidelity by molting termites in Formosan subterranean termite, Coptotermes formosanus Shiraki colonies is a new addition to our understanding of lower termites’ behavior and biology. Our previous studies indicated that workers moved to the central nest to molt in the presence of eggs and reproductives. The current study showed that noviflumuron-affected workers also return to the central nest and died in the vicinity of reproductives and eggs. The aversion to the dead and decaying workers caused reproductives and brood to leave the original central nest site in a colony and refuge at newer sites every few days in response to newly dead workers near them. Because mortality was an event observed only in workers undergoing molting under the effect of noviflumuron- a CSI, the death of molting individuals was observed only around reproductives and brood. This study reveals a previously undiscovered behavior of molting termites and the mechanics behind a successful arsenal; noviflumuron baits used against subterranean termites.

Area-Wide Elimination of Subterranean Termite Colonies Using a Novaluron Bait

“…In general, R. flavipes colonies occupied a small foraging range with minimal overlap between colonies, which is consistent with what was found in previous studies [16,44,46]. In a few instances, two colonies were collected from the same station at different times, and this may be due to the utilization of another colony's pre-formed foraging tunnels [36,47,48].…”

“…These site-specific control measures attempt to protect the structure from invading colonies, but the overall threat of re-infestation remains as neighboring colonies can move into these vacated areas [33,34]. Termite baits are used as both curative and preventative measures against subterranean termites and have been shown to eliminate colonies [30,35,36]. The active ingredients of most termite baits are chitin synthesis inhibitors (CSI), which cause mortality in the workers when they return to the nest to molt and spreads through the colony through trophallaxis.…”

Concentration-Dependent Feeding Deterrence to 20-Hydroxyecdysone for Three Subterranean Termite Species (Blattodea: Rhinotermitidae)

“…Baits containing CSIs are known to cause mortality in termites through disruption of the molting process [ 2 , 6 , 19 ]. Similarly, individuals that fed on 20E (100 and 1000 ppm) exhibited hyperecdysonism in C. formosanus and R. flavipes , and displayed dose-independent mortality while the mortality occurred in a shorter time period (≈12 days) than CSIs, suggesting 20E could be used to enhance the speed of termite baiting systems [ 13 , 20 ].…”

“…It has been demonstrated that foraging populations of C. formosanus will molt two weeks after field collection [ 16 ], indicating that termites that have consumed a lethal dose of a CSI do not die until reaching their next molting cycle, at which point ecdysis cannot be successfully completed [ 17 , 18 ]. A recent study found that termites always return to the central nest prior to molting where reproductives, eggs and younger brood are located, and die near them if termites have ingested CSI baits [ 19 ].…”

Application strategies by selective medium treated with entomopathogenic bacteria Serratia marcescens and Pseudomonas aeruginosa as potential biocontrol against Coptotermes curvignathus

“…However, the bait method may be able to attract termites to feed on it and cause intoxication through ingestion. Foraging termites will ingest toxins within the bait and then carry these toxins back with them to the colony, where they will share the lethal bait with their nest-mates [4].…”