HEAT TOLERANCE OF STRUCTURE-INFESTING DRYWOOD TERMITES (ISOPTERA, KALOTERMITIDAE) OF FLORIDA

Heat tolerance studies were conducted against Cryptotermes brevis (Wal ker) and Incisitermes snyderi (Light) pseudergates to determine temper ature and heating time requirements at target sites for controlling st ructural infestations. Complete mortality of C. brevis was obtained fo llowing exposure times of 4 and 10min at 50 and 48 degrees C, respecti vely, while I. snyderi required a minimum 15min exposure at 50 degrees C. Relative humidities (RH, ca. 10, 50, and 90%) did not significantl y influence the heat tolerance of C. brevis. Mortality was similar in termites exposed to these RH levels within exposure times (25, 35, and 45min) when termites were heated to 45 degrees C indicating that the amount of water vapor in the air had no effect on heat tolerance of th is species. The rate at which the temperature was increased significan tly affected C. brevis mortality only at 50 degrees C with a 1min hold time. Pseudergates treated with the slowest temperature increase (0.5 degrees C/min) had the highest mortality compared with the more rapid increases (1.0 and 3.0 degrees C/min). Gradual acclimation of C. brev is pseudergates at 35 degrees C for 10d had no significant effect on h eat tolerance. The recommended commercial exposure of 54.4 degrees C i nternal wood temperature for 60min will achieve control of economicall y important drywood termites in Florida and could be substantially red uced if temperatures of all target sites can be monitored.