Lower Supercooling Points Research Articles

Adaptations to low temperature in high altitude insects from Mount Kenya

Abstract. 1. The strategies for low temperature survival in insects on Mount Kenya were investigated. The insects were collected from their natural habitats and their supercooling points and low temperature tolerances determined.2. Most insects showed no special adaptations to low temperature survival and seem to depend on spending the cold nights in protected habitats, such as beneath stones and fallen trunks of plants, as well as within the wet frills of dead leaves of alpine plants, where they are protected by the heat released from freezing water.3. Some insects, e.g. Collembola, aphids and a curculionid beetle, which live in relatively unprotected habitats, had low supercooling points, allowing them to remain unfrozen when exposed to low night temperatures. A nucleator free diet is apparently essential for the survival of such species.4. Two species of curculionid beetles were found to withstand freezing down to ‐7d̀C. These beetles had nucleating agents in their haemolymph and higher supercooling points than most of the other species studied.5. A moderate freezing tolerance was found in larvae of a midge that lives in the watery liquid between the leaves of Senecio brassica.

Relationship between diapause and spercooling in the blowfly, Lucilia sericata (Mg.) (Diptera: Calliphoridae).

Experiments on the supercooling ability of the blowfly, Lucilia sericata (Mg.), in its prepupal diapause stage and in all life stages undergoing normal development have been carried out to determine the correlation between diapause and cold-hardiness. Results have demonstrated that the range in ability to supercool is the same in diapause larvae whether or not they have been cold-acclimated at 3 °C for varying periods of up to 9 weeks, and that diapause larvae and prepupal, non-diapause stages exhibit about the same degree of cold-tolerance. During normal development the egg and pharate adult stages have the lowest supercooling points, with the larva showing a gradual decline in ability to supercool throughout its feeding period until cessation of feeding, which occurs about 4 days before puparium formation. The results indicate that the physiological and biochemical processes leading to diapause induction do not enhance the supercooling potential of this species, and that cold-acclimation does not appear to be a prerequisite for the successful overwintering of the diapause larvae of L. sericata, at least in this part of its range in southwest British Columbia.