Submitted to: Sociobiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/1997
Publication Date: N/A
Interpretive Summary: Heat treatments for the control of drywood termite infestations were investigated. The two major drywood termite pests of Florida were tested for their heat tolerance. Additional studies were conducted to determine the influence of relative humidity, the rate of temperature increase, and the temperature at which the termites were raised on termite heat tolerance. We found that effective eastern drywood termite control could be achieved when exposed to temperatures of 48 or 50 C for 10 or 4 minutes, respectively. Neither humidity nor the temperature at which the termites were raised had an effect of heat tolerance. However, the termites were more sensitive to slower than more rapid heating rates. Although the current heat treatment recommendations may be excessive they should be effective at controlling infestations by these species. Expenses could be reduced by decreasing the temperate or exposure time of the treatment.
Technical Abstract: Heat tolerance studies were conducted against CryHeaptotermes brevis and Incisitermes snyderi pseudergates to determine temperature and heating time requirements at target sites for controlling structural infestations. Complete mortality of C. brevis was obtained following exposure times of 4 and 10 min at 50 and 48 C, respectively, while I. snyderi required a minimum 15 min exposure at 50 C. Relative humilities (RH, ca 10, 50, and 90%) did not significantly influence the heat tolerance of C. brevis. Mortality was similar in termites exposed to these RH levels within exposure times (25, 35, and 45 min) when termites were heated to 45 C indicating that the amount of water vapor in the air had no effect on heat tolerance of this species. The rate at which the temperature was increased significantly affected C. brevis mortality only at 50 C with a 1 min hold time. Pseudergates treated with the slowest temperature increase (0.5 C/min) had the highest mortality compared with the more rapid increases (1.0 and 3.0 C/min). Gradual acclimation of C. brevis pseudergates at 35 C for 10 d had no significant effect on heat tolerance. The recommended commercial exposure of 54.4 C internal wood temperature for 60 min will achieve control of economically important drywood termites in Florida and could be substantially reduced if temperature of all target sites can be monitored