Comparison of Constant and Alternating Temperatures for Determining Developmental Rates of Mexican Bean Beetle Eggs and Pupae

Abstract

Eggs and pupae of the Mexican bean beetle, Epilachna varivestis Mulsant, were incubated at four constant temperatures (15, 20, 25, and 30°C) and at four alternating-temperature regimes (10 and 20, 15 and 25, 20 and 30, or 25 and 35°C), with 12 h of each temperature per day. Except for the intermediate constant temperatures of 20 and 25°C, the percent survival and median developmental rate were lower at each other constant temperature compared with the same temperature within an alternating regime. This suggests that only an intermediate range of constant temperatures is suitable for developmental studies and that alternating-temperature regimes should be utilized for determining developmental rates at both lower and higher temperatures. An alternative interpretation would be that development accumulation under alternating-temperature regimes is not simply the additive result of the development observed under constant-temperature conditions.