Effects of decreasing thermophotoperiod on the eastern subterranean termite (Isoptera: Rhinotermitidae)

Abstract

Eastern subterranean termite, Reticulitermes flavipes (Kollar), workers were exposed to decreasing temperatures and a shift in photoperiod to simulate conditions that are encountered during the fall in eastern Nebraska. Mean water and fat content in termites exposed to a decreasing thermophotoperiod did not differ significantly from controls or laboratory colony termites. Survival was higher for termites subjected to a decreasing thermophotoperiod than for controls. This could be attributed to acclimation to low temperatures or a delayed mortality due to lowered metabolic activity at low temperature. Previously reported data on soil temperatures taken in Lincoln, NE, at a depth of 91.4 cm showed that the temperature rarely went below 0°C. Our results, observations from previous reports of R. flavipes found at depths >100 cm during the winter, and previously determined lower lethal temperatures and supercooling points suggest that successfully overwintering R. flavipes colonies retreat to soil depths where freezing temperatures are not encountered.