Meeting Abstract

P2.27  Friday, Jan. 4  Effect of Prior Freeze Exposure on Cold Hardiness of Woolly Bear Caterpillars LESZCZYNSKI, Christine F*; LAYNE, JR., Jack R.; Slippery Rock Univ., Pa; Slippery Rock Univ., Pa cxl9371@sru.edu

Woolly bear caterpillars (Pyrrharctia isabella) hibernate under leaf litter and throughout much of North America this causes them to be exposed to freezing temperatures. Prior to winter woolly bears produce glycerol as a cryoprotectant to enable them to withstand harsh temperatures. The effect of prior freezing on glycerol levels and survival rates in woolly bear caterpillars were studied here. Thirty woolly bears were collected from Butler County, Pennsylvania during October 2006. Ten woolly bears served as an unfrozen control and were kept at 3 C (no freeze exposure), ten woolly bears were exposed to -4 C for four days, and ten woolly bears were first exposed to -4 C for two days, then -8 C for two days (harsh freeze). After one week of hydration at 3 C, glycerol levels and survival rates were observed. There was a significant difference (P < 0.05) between the harsh freeze and the control group concerning the glycerol levels. The caterpillars in the harsh freeze showed an increase in glycerol levels that was 3X higher than the level in the unfrozen caterpillars (mean � SD) 181 � 33 to 490 � 127 mmol/L. The -4 C group did not show a significant change in glycerol levels. Survival rates for both of the two groups of freeze exposures had less than 50% survival rate. Nearly 45% of the caterpillars pupated in the -4 C freeze, and slightly over 36% emerged as moths. Nearly 44% of the caterpillars pupated after the harsh freeze, and nearly 44% emerged as moths. These results show that by exposure of woolly bears to a harsh freeze can trigger additional glycerol production, which may render them more resistant to future harsh freezes.