Chill injury in the eggs of the migratory locust, Locusta migratoria (Orthoptera: Acrididae): the time-temperature relationship with high-temperature interruption

Mortality of the overwintering egg of the migratory locust, Locusta migratoria L., was attributed to chill injury because of its occurrence well above the egg's super cooling point. In this study, two parameters, upper limit of chill injury zone (ULCIZ) and sum of the injurious temperature (SIT), were used to examine the locust egg's cold hardiness. The value of ULCIZ for the locust egg is 1.06 ± 0.54°C, and the SIT is -329.7 (hour · degree). The superoxide dismutase (SOD) and catalase (CAT) activities changed dramatically after cold stress, indicating that oxygen and hydroxide free radicals are probably efficiently detoxified at low temperatures. It was suggested that the nature of chill injury in locust egg might be a complex of metabolic disorder and a non-proportional decrease in enzymatic reaction and transports, because the LDH activity at low temperature increased significantly and the ATPase activity decreased with prolonged duration of exposure to low temperatures. The results from high temperature interruption revealed that the high temperature intervals significantly increased the survival of locust eggs.