Date of this Version
Cold acclimation and cold tolerance were studied in laboratory-reared diapausing pink bollworms, Pectinophora gossypiella (Saunders), conditioned at 5°, 10°, and 15° C for 2,4, and 8 wk. Larval mortality, abnormal pupation and total mortality from 2-h exposure to sub-zero temperatures increased similarly as the temperature decreased from _6° to -15° C. Exposure to -9° C and above had little effect. The effect of cold conditioning on cold tolerance was most important at the _12° C exposure. Conditioning at 5°, 10°, and 15° C reduced total mortality after exposure to _12° C, compared to unconditioned larvae. Conditioning of larvae at 10° C for 8 wk resulted in the least mortality of all treatments. Water content decreased as duration of conditioning increased, with no significant differences between conditioning temperatures. Decreased water content did not correlate well with observed changes in cold tolerance.