Role of chilling in the acquisition of cold tolerance and the capacitation to express stress proteins in diapausing pharate larvae of the gypsy moth, <i>Lymantria dispar</i>

Abstract

Abstract Cold hardiness in eggs (pharate first instar larvae) of the gypsy moth is not a component of the diapause program, but is acquired only after the pharate larvae have been chilled. The supercooling points of unchilled (25°C) and chilled (5°C) eggs are nearly the same (ca. −27°C), and chilling does not further elevate concentrations of glycerol, the major cryoprotectant, yet chilling at 5°C greatly increases the pharate larva's tolerance of −20°C. One conspicuous difference between the chilled and unchilled pharate larvae is their ability to express stress proteins. The most abundantly expressed stress protein, 75,000 M r , was expressed more highly in chilled pharate larvae than in unchilled pharate larvae, both at high temperatures (&gt; 40°C) and in response to low temperature (−15°C). This correlation suggests a link between stress protein synthesis and the acquisition of cold tolerance. © 1992 Wiley‐Liss, Inc.