Survival and Feeding Responses of the Formosan Subterranean Termite to Wood Treated with Menadione and Menadione Sodium Bisulfite

The Formosan subterranean termite, Coptotermes formosanus Shiraki, is an invasive species and among the most economically damaging structural pest worldwide. Various insecticides and natural substances have been investigated for their management. Among these, naphthoquinones have demonstrated insecticidal activity against termites and diverse other insect pests. Menadione (vitamin K₃), a naphthoquinone derivative, has been examined for its toxicity and repellency against C. formosanus when applied to soil, the tunneling substrate for termites. However, its potential for wood preservation was not investigated. In this study, we tested the water-insoluble menadione and its water-soluble derivative, menadione sodium bisulfite (MSB), for their effects on survival and food consumption in C. formosanus through wood treatment over 28 days. Our results revealed toxic effects of both compounds, with significant termite mortality observed between 500 and 1000 ppm in a no-choice assay. In a choice assay where termites were provided with treated and untreated wood, menadione at concentrations ≥ 500 ppm exhibited a strong feeding deterrent effect and reduced wood damage. However, such effects were not consistently detected for MSB ranging from 1 to 1000 ppm. These findings suggest that menadione is more effective than MSB and may have greater potential as a wood preservative.