Locomotor Response of Folsomia Candida (Collembola: Isotomidae) to Cooling Temperatures

Groups of Folsomia Candida (Willem) were chilled to 0°C and warmed back to room temperature to measure their locomotor response to cooling and determine the chill coma temperature of the species. Results showed that the frequency of walking springtails, in groups being chilled down to 0°C, was initially similar to that of control groups held at room temperature before consistently declining to chill coma thresholds well above the freezing point. Body size had a significant effect on response to chilling but not to recovery. Jumping, in groups being chilled, was absent from tests conducted in humid arenas but an important part of the locomotor response in dry arenas. Chill coma thresholds were higher in dry than in humid arenas. In a 4–33°C thermal gradient, warm-acclimated and cold-acclimated springtails distributed themselves over the whole gradient, but with a preference for sections at 8–11 and 5–8°C, respectively. Together, test results did not support the hypothesis that, for F. Candida, locomotion is the main strategy to avoid cold temperatures. Results suggest that F. Candida remain in the upper soil layers as the season becomes colder and increase their cold tolerance to continue foraging in the food-rich upper soil layers. Survival of the species to freezing temperatures may depend more on development of cold tolerance and cold hardiness (supercooling) than on relocation to warmer deeper soil lavers.