Effects of prolonged freezing and supercooling on body composition, pupariation, and adult emergence of Eurosta solidaginis (Diptera : Tephritidae)

Freeze tolerance and enhanced super-cooling ability (freeze avoidance) are distinct, adaptations in insects facilitating survival of subfreezing tempe ratures. It has been suggested that freeze tolerance has advantages over fr eeze avoidance with respect to certain aspects of insect ecophysiology. Thi rd instars of the gall flu Eurosta solidaginis Fitch were kept either froze n or supercooled at -5 degreesC for 10 wk. Supercooled larvae lost 26% of t heir wet weight and frozen larvae lost 14% of wet weight, mostly as a resul t of water loss during the treatments. Moreover, although supercooled larva e lost more water than did frozen larvae, lipid content was stable througho ut both treatments. Freeze-treated larvae were 50% more likely than superco ol-exposed larvae to survive to pupariation and adult emergence. E, solidag inis larvae survived prolonged freezing better than they endured prolonged super cooling, but it remains to be clarified whether or riot this effect c an be attributed to differences in water retention.