INOCULATION TRIGGERS FREEZING AT HIGH SUBZERO TEMPERATURES IN A FREEZE-TOLERANT FROG (RANA-SYLVATICA) AND INSECT (EUROSTA-SOLIDAGINIS)

Animals may be in direct contact with external ice or snow at temperatures above the supercooling point of their body fluids; ice nucleation may occur across the epithelium or cuticle, causing the freezing of body fluids. Two freeze-tolerant animals are wood frog Rana sylvatica and goldenrod gall fly Eurosta solidaginis. Frogs remained supercooled for 3 h at -1.5 to -2.0°C when kept on an unfrozen surface, but they began to freeze in <30 s after coming in direct contact with ice crystals. Seeding occurred in <1 min across isolated patches of frog skin held in a modified. Ussing chamber. Similarly, externally moistened larvae of E. solidaginis froze at higher temperatures than dry larvae. Likewise, within galls containing a relatively high water content (65.8%), larvae froze at higher temperatures than ones found in drier galls (19.6%). In E. solidaginis, exposure to sufficient moisture to trigger inoculation declines as winter approaches; thus, this avenue for freezing seems limited to autumn, when plant galls have a high water content. -from Authors