U. Gehrken et Te. Southon, EFFECT OF TEMPERATURE ON COLD-HARDINESS AND TISSUE ICE FORMATION IN THE ADULT CHRYSOMELID BEETLE MELASOMA-COLLARIS L, Journal of insect physiology, 43(6), 1997, pp. 587-593
The freeze-tolerant chrysomelid beetle Melasoma collaris overwinters i
n plant litter on windswept ridges or covered with snow for 8-9 months
in the Norwegian alpine region. Lower lethal temperature, supercoolin
g and melting point depression were correlated to accumulation of glyc
erol. The lower limit of freeze tolerance was associated with the free
zing of 73-75% body water, About 23-15.5% of the body water was osmoti
cally inactive, and the highest percentage was revealed in individuals
depleted of glycerol at 21 degrees C. A shift in cooling rate from 1
degrees C min(-1) to 1 degrees C every 13.5 min lowered nucleating tem
perature markedly. The alteration in nucleating activity probably aris
es from the structure of the haemolymph nucleating agent that function
s to slow embryo growth at the slow cooling rate. An enhanced supercoo
ling is particularly beneficial in autumn before M. collaris has accum
ulated glycerol, since supercooled individuals accumulate glycerol in
higher concentrations than frozen ones. Freezing at higher temperature
s is probably a better survival strategy during brief intervals with p
ronounced decrease in air temperature. (C) 1997 Elsevier Science Ltd.