Effects of constant and fluctuating temperatures on development and reproduction of Megoura crassicauda and Aphis craccivora (Hemiptera: Aphididae)

Abstract

The influence of fluctuating temperatures on the development and fecundity of two aphids, Megoura crassicciudci Mordvilko and Aphis craccivora Koch, were determined by collecting life table data at a constant temperature (22 °C) and two fluctuating temperatures (22 ± 3 °C and 22 i 5 °C). The longevity of M. crassi- cauda decreased significantly at 22 ± 3 °C and 22 ± 5 °C, while there was no significant difference in the longevity of A. craccivora among the three treatments. The fecundity and intrinsic rate of increase (r) of M. crassicauda decreased significantly at both fluctuating temperatures, while A. craccivora showed the opposite tendency. These results showed that the fluctuating temperatures had negative impacts on the life history traits ofM. crassicauda, but were bencficial for A. craccivora. Data obtained under constant temperatures may not reveal accurately enough the biotic responses of pests in the field.