Effects of brief exposure to high temperatures on the survival and fecundity of Athetis lepigone (Lepidoptera: Noctuidae).

ABSTRACT

In Huang-Huai-Hai Summer Corn Region of China, brief periods of high summer temperatures have been reported with increasing frequency in recent years. Athetis lepigone is a cosmopolitan insect which causes severe damage on summer corn seedlings. To understand how high summer temperatures may affect the population dynamics of A. lepigone, we exposed different developmental stages (1, 2 and 4-day old eggs; 1, 6, 12 and 18-day old larvae; 1, 3 and 6-day old pupae; and 1 and 2-day old female and male adults) to 41 °C for periods of various length (0.5, 1, 2, 4 and 6 h) The rearing temperature (constant 26 °C) was used as control. After heat treatment, all individuals were transferred to a 26 °C climate chamber for further development. The effects on immediate survival, maturation success to adulthood, and female fecundity were studied. Eggs, young larvae, late pupae and newly emerged adults had relatively higher immediate survival rates than the other experimental groups. Heat treatment at the egg and larval stages had no impact on development to adulthood and on female fecundity, while it significantly reduced the survival rate of larvae but not of eggs. Brief exposure to high temperature during the early pupal stage and as adults depressed female fecundity whereas exposure during the late pupal stage had no effect.