Cold hardiness adaptations of codling moth, Cydia pomonella

The cold hardiness adaptations of natural and laboratory reared populations of the codling moth, Cydia pomonella, were examined. Hemolymph, gut, and w hole body supercooling points (SCPs), 24-h LT(50)s, polyhydroxy alcohol con centrations, hemolymph freezing points, and hemolymph melting points were d etermined. Nondiapausing codling moth larvae do not have appreciable levels of ice nucleators in the hemolymph or gut. Whole body supercooling paints were higher than hemolymph supercooling points. For nondiapausing larvae, L T(50)s were significantly higher than both the whole body and the hemolymph supercooling points, indicating the presence of chill sensitivity. As the larvae left the food source and spun a cocoon, both hemolymph and whole bod y SCPs decreased. Diapause destined larvae had significantly lower hemolymp h SCPs than nondiapausing larvae, but whole body SCPs were not significantl y different from nondiapausing larvae of the same age. The LT(50)s of diapa use destined and diapausing larvae were significantly lower than that of no ndiapausing larvae. Codling moths are freezing intolerant, with LT(50)s clo se to the average whole body supercooling point in diapause destined and di apausing larvae. The overwintering, diapausing larvae effectively supercool to avoid lethal freezing by removal of ice nucleators from the gut and bod y without appreciable increase of antifreeze agents such as polyols or anti freeze proteins.