Cold hardiness in the collembolan Orchesella cincta under different food conditions

Abstract

The effect of dietary nitrogen on the ability of the collembolan Orchesella cincta to develop cold tolerance was studied. Animals fed for 6 weeks under summer conditions on the fungus Cladosporium cladosporioides containing 2.3% nitrogen.had a higher lipid and lower protein concentration than those fed on the same fungus containing 4.3% nitrogen. After 6 weeks, the animals were placed under winter conditions, and their cold tolerance and hemolymph osmolality was tested weekly. No effect of the food treatment was found for these parameters. Because starvation did not increase the cold tolerance of the animals, elimination of ice nucleators in the gut is not thought to be a mechanism for increasing cold tolerance in this species. Winter acclimation increased survival of exposure to cold; the animals were able to survive an exposure to −3°C for 1 week after 2 weeks acclimation at winter conditions. Hemolymph osmolality did not change with the increased cold tolerance of the animals. It is concluded that O. cincta does not use osmotically active cryoprotectants to develop cold tolerance. The animals may use antifreeze proteins to increase cold tolerance.