Cold and drought stress in combination with pyrene exposure: studies with Protaphorura armata (Collembola: Onychiuridae).

Adult survival of the springtail Protaphorura armata exposed to pyrene, a common soil pollutant, was investigated in combination with cold and drought stress, in three separate experiments. (1) A drought stress imposed subsequent to pyrene exposure in soil resulted in a significant decrease in springtail survival, when compared with controls exposed to pyrene and subsequently to 100% relative humidity. (2) A previous exposure to drought stress resulted in slightly improved survival of pyrene exposure at a concentration of 10mg/kg, but not at higher pyrene concentrations. When comparing tests 1 and 2, better survival was found in the latter test. When comparing the drought survival of springtails that had been previously exposed to pyrene with drought survival of springtails with no previous history of pyrene exposure, survival was significantly lower in the former. (3) Springtail survival of pyrene exposure was investigated at several temperatures. Springtails showed a significant improvement in survival at temperatures fluctuating between +1 degrees C and -1 degrees C in 12:12-h cycles, and at a constant -3 degrees C, at the highest pyrene concentration (300 mg/kg), while survival remained the same at all temperatures when springtails were exposed to lower pyrene concentrations. It is concluded that temperature and water availability are important factors when assessing the springtails' susceptibility to pyrene exposure.