LOW-TEMPERATURE EFFECTS ON SURVIVAL OF THE EASTERN SUBTERRANEAN TERMITE (ISOPTERA, RHINOTERMITIDAE)

Reticulitermes flavipes (Kollar) (third and fourth instar) workers fro m a laboratory colony were subjected to 0-degree-C for either 10 or 30 d after having been exposed to 10-degrees-C for varied periods from 0 to 30 d. Worker mortality increased with increased exposure to 10-deg rees-C. The lowest percentage of mortality was observed in workers exp osed to 0-degree-C for 10 d after 0 d of 10-degrees-C acclimation. Wor kers exposed to 0-degree-C for 30 d exhibited high mortality rates reg ardless of the duration of the 10-degrees-C acclimation periods. The s upercooling point of laboratory reared termite workers generally incre ased with prolonged exposure to 10-degrees-C. Termite workers subjecte d to 0-degrees-C for 10 d did not exhibit lower supercooling points fo llowing increased acclimation periods at 10-degrees-C. However, termin tes subjected to 0-degrees-C for 30 d generally did exhibit decreased supercooling points following increased exposure to acclimation temper atures at 10-degrees-C. Lower lethal temperatures were higher than the supercooling points for laboratory workers exposed to 10-degrees-C fo r 0, 1, and 10 d and for field collected workers during the months of May to July 1992. However, lower lethal temperatures were lower than s upercooling points for laboratory termites exposed to 10-degrees-C for 20 and 30 d and for field collected termites during the months of Sep tember to November 1992. These data indicate that 10-degrees-C cold ac climation of R. flavipes does not result in lower supercooling points in either laboratory maintained or field collected samples. However, d ecreased lower lethal temperatures in response to either cooler season al temperatures or longer exposure does indicate that a switch from pr efreeze mortality to freeze tolerance may be occurring.