THERMAL TOLERANCES OF 4 TERMITE SPECIES (ISOPTERA, RHINOTERMITIDAE, KALOTERMITIDAE)

Upper thermal tolerances were determined for four species of termite p seudergates and nymphs using both a preset temperature method and a bi oassay in which the temperature was increased at a known rate. Termite s were acclimated at 28 degrees C for a minimum of 24h prior to being placed into an oven preset to temperatures of 40 degrees C to 49 degre es C, or placed into an oven at room temperature (ca. 25 degrees C) wh ich was then raised at 1.0 degrees C/min. In preset bioassays, the low est temperature that caused 100% mortality in all replicates was 42 de grees C for Coptotermes formosanus Shiraki and 45 degrees C for Incisi termes immigrans (Light). In temperature rate bioassays, upper lethal limits (ULL) were 47.9 degrees C, 51.0 degrees C, 51.3 degrees C and 5 1.3 degrees C for C. formosanus, I. immigrans, Neotermes connexus Snyd er, and Cryptotermes brevis (Walker), respectively. These elevated ULL values could be due to a time-lag between the body temperature and th e chamber temperature, or result from increased thermotolerance; both of which are possibilities with gradually increasing temperatures. Act ual lethal thresholds are likely to be lower than observed lethal tole rances generated by the ULL method.