D3012: Effect of soil moisture on survivorship, tunneling, and food consumption in Coptotermes formosanus and Reticulitermes flavipes (Blattodea: Rhinotermitidae)

Substrate moisture is a critical environmental factor for the survival and behavior of subterranean termites (Rhinotermitidae). The invasive Formosan subterranean termite (Coptotermes formosanus) and the native eastern subterranean termite (Reticulitermes flavipes) co-occur in the southeastern United States. Tunneling activities of subterranean termites are promoted by positive moisture gradients, however, no research presents influences that constant soil moisture contents have on their behavior. We hypothesized that foraging activity and survivorship of both species alter in response to varying soil moisture contents. To test this, an experiment was performed where tunnel area, food consumption, and survivorship were documented for 28 days under six sand moisture regimes (0%, 1%, 5%, 15%, 25%, 30%) in both C. formosanus and R. flavipes. We found that, for both species, no tunneling or feeding activity was performed at 0% moisture, while no significant difference was found on tunnel area or food consumption among other tested conditions. Survivorships of termites at 0% and 1% were significantly lower than that at 5%, 15%, and 25% for C. formosanus, with mortality at 30% not significantly different from other groups. For R. flavipes, survivorships at 0% and 1% were significantly different from 5%, 15%, and 30%, with mortality at 25% not significantly different from other groups. At minimum, 1% soil moisture is needed for foraging and 5% to prevent colony death in both species. The results supported our hypothesis and highlighted the importance of soil moisture for foraging and survival of subterranean termites.