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

G Kakkar,W Osbrink,N.-Y Su

doi:10.1038/s41598-018-19603-8

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.

Highlights

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
Amongst strategies available for control of subterranean termites, chitin synthesis inhibitor (CSI) incorporated baits have been demonstrated to be a successful method for elimination of subterranean termite colonies[4]
Because molting took place in the central nest, we hypothesize that noviflumuron-affected termites may die near reproductives and broods instead of the foraging sites, which prevents the aversion of dead termites at bait stations

Summary

Treatment Control Noviflumuron Statistical analysis

Quantity of bait may be killed quickly, negating the slow-acting requirement of a successful bait AI. CSIs like noviflumuron interfere with the formation of cuticle and affect the molting process of workers, but those ingested lethal doses of CSIs are not affected until the onset of ecdysis, independent of dose. This may explain, in part, why only baits incorporating CSIs were successful in eliminating termite colonies as reported in many field studies[4,10]. A recent study by Kakkar et al.[11] showed that termites move back to central nest near reproductives and brood to complete the molting process and this molting-site fidelity may offer another explanation for the success of noviflumuron baits to eliminate termite colonies.

Results and Discussion

Materials and Methods

Additional Information