COLD HARDNESS OF SOME ARCTIC SPIDER SPECI ES

The lower temperature limit for motor activity of Pardosa glacialis, P . lapponica, Theridion impressum from Ellesmere Island, the Mackenzie River delata, the Kolyma River and the Khibini mountains was determine d. P. glacialis kept its activity under positive temperatures up to 0 degrees C. All the spider individuals, held at subzero temperature, be come active at -0.15-1.0 degrees C, P. lapponica kept activity up to 2.6...+3.1 degrees C, T. impressum was active at +1.5...+2.0 degrees C . Supercooling points of P. glacialis, P. lapponica, and T. impressum were examined. All the species studied were freezing intolerant and sh ew the trend of decreasing cold hardiness with age. The first instars were the most cold hardy. There were no differences between the superc ooling capacity of spider populations and various geographical areas. Low temperatures of supercooling points at the overwintering stages of development allow the species to spread to the north.