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

Authors: KAKKAR, GARIMA - University Of Florida; Osbrink, Weste; SU, NAN-YO - University Of Florida

Submitted to: Nature Scientific Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/4/2018
Publication Date: 1/19/2018
Citation: Kakkar, G., Osbrink, W.L., Su, N. 2018. Molting site fidelity accounts for colony elimination of the Formosan subterranean termites (Isoptera: Rhinotermitidae) by chitin synthesis inhibitor baits. Nature Scientific Reports. 8:1259.

Interpretive Summary: Where it occurs, the Formosan termite is the most devastating termite pest in the world. This termite is well established in the south eastern part of the United States. Whole colonies with a king and queen were studied in large ant farms to determine the dynamic interaction of molting of Formosan termite workers in laboratory-reared colonies. It was determined that termite workers return to the main nest near the royal pair (king and queen) and brood (eggs and young termites) to molt. It was further determined that as the molting workers treated with chitin synthesis inhibitor (CSI) baits die, the king and queen termites relocate to avoid the diseased environment. This cycle is repeated until the royal pair also dies. This is important because other toxicants that kill near the bait stations cause repellency of other termites due to the decomposition of their bodies, thus preventing further poisoning of the colony. We have demonstrated that with CSI baits, the termites return to the nest to molt and die and do not contaminate the bait station with repellent dead termites. This provides an opportunity to accelerate such induced mortality using molting hormones or their mimics to speed up colony destruction.

Technical 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. Current study showed that chitin synthesis inhibitor (CSI)-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 seek 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 CSI, 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: CSI baits used against subterranean termites.