Eur. J. Entomol. 96 (2): 165-168, 1999
Chill injury at alternating temperatures in Orchesella cincta (Collembola: Entomobryidae) and Pyrrhocoris apterus (Heteroptera: Pyrrhocoridae)
Survival and Lt50 after exposures at constant low temperature were compared to the values obtained at alternating temperatures in two active (summer acclimated) temperate terrestrial arthropods. The experimental regimes used interruptions - daily transfers from the lower temperature to various higher temperatures for two hours or to one high temperature for Various durations. In both species the alternating conditions improved survival, implying reparation of the chill injury. In the collembolan Orchesella cincta, there was a maximum Lt50 when the higher exposure temperature was equal to the temperature of rearing (19°C). In the bug Pyrrhocoris apterus, Lt50 increased strongly with increasing higher temperature from 0 to 15°C, and was subsequently constant over the entire physiological range suitable for development (to 35°C). Exposure at 0°C was harmful if continuously applied, but survival increased, relative to a constant exposure at -5°C, if the temperature alternated between -5 and 0°C.
Keywords: Cold hardiness, chill injury, low temperature, survival, mortality, Collembola, Orchesella cincta, Heteroptera, Pyrrhocoris apterus
Accepted: January 15, 1999; Published: June 30, 1999