抄録
Mean supercooling points of the spotted cutworm, Xestia c-nigrum, dropped from -8°C to -17--18°C and mean contents (mg/g) of glycerol and trehalose rised respectively from 6 to 12 and from 17 to 26 by cold hardening, although hardening at -5°C for 10 days and 30 days showed no appreciable difference. Mean supercooling points by ice inoculation was -4.4°C. This species is weakly freezing-tolerant. Post-thawing survival was relatively high (57-70%) by spontaneous freezing after cooling to -12°C or by inoculative freezing after cooling to -20°C, but was virtually 0% by spontaneous freezing after cooling to -20°C. No appreciable difference due to instar was found on above aspects. Survival after spontaneous freezing from -6 to -12°C was confirmed under early winter field conditions. Wild larvae kept under field conditions during winter died less than those laboratory-reared ones and did not moult as latter did.
