Effects of Menadione on Survival, Feeding, and Tunneling Activity of the Formosan Subterranean Termite

SIMPLE SUMMARY: Subterranean termites are wood-feeding insects that construct foraging tunnels in soil to search for cellulose-based food sources. The Formosan subterranean termite is an invasive species to the United States and one of the most destructive termites in the world. Management of these termites depends on understanding termite behavior and the use of termiticides that are effective, safe, and cost-efficient. Menadione, also known as vitamin K3, is safely used in animal feeds but toxic to some insects due to disruption of energy production by interference with mitochondrial respiration. In this study, we examined how menadione affected the survival, feeding, and tunneling activity of the Formosan subterranean termite. We found that when menadione was applied to food (paper) or tunneling substrate (sand), this compound caused mortality and reduced feeding activity in termites in a dose-dependent manner. When provided with both treated and untreated sand, termites were deterred from tunneling and feeding on the side treated with menadione. Overall, our findings demonstrated strong toxicity and repellency of menadione against the Formosan subterranean termite, suggesting this compound can be potentially used as a termite control agent. ABSTRACT: The Formosan subterranean termite, Coptotermes formosanus Shiraki, is a highly destructive pest and a cosmopolitan invasive species. Sustainable termite management methods have been improving with the search for novel insecticides that are effective, safe, and cost efficient. Menadione, also known as vitamin K(3), is a synthetic analogue and biosynthetic precursor of vitamin K with low mammalian toxicity. Menadione has shown insecticidal activity in several insects, presumably due to interference with mitochondrial oxidative phosphorylation. However, little is known about its effectiveness against termites. In this study, we evaluated the toxicity and repellency of menadione in C. formosanus. Our results showed that menadione affected the survival and feeding activity of termites both in filter paper and substrate (sand) treatments, and menadione influenced termite tunneling activity in treated sand. In a no-choice assay, ≥90% mortality after seven days and minimal or no food consumption were recorded when sand was treated with menadione at 6 to 600 ppm. In a two-choice assay with a combination of treated and untreated sand, termites were deterred by menadione at 6 to 600 ppm and exhibited low mortality (≤30%) over seven days, while tunneling activity was prevented with 60 to 600 ppm of menadione treatment. Overall, our study demonstrated dose-dependent toxicity and repellency of menadione in C. formosanus. The potential use of menadione as an alternative termite control agent is discussed.