Low Temperature Effects on Development, Mortality, Fecundity, and Viability of the Ectoparasitoid Catolaccus grandis (Hymenoptera: Pteromalidae)1

Abstract

The low temperature threshold for development of Catolaccus grandis (Burks) was 12°C for eggs, 11.5°C for larvae, and 9.5°C for pupae. The developmental time for male or female parasitoids increased by 4.6 to 5.3 times and the preovipositional period of females increased from 2.2 to 9.3 days when the temperature was reduced from 30°C to 15°C. The number of degree-days to complete development was 225.6 for females and 197.2 for males. The mean duration of emergence for C. grandis ranged from 2.6 days at 27°C - 30°C to 5.7 days at 20°C. Reduction of the temperature from 25°C to 15°C increased the death rate of C. grandis 2.3 times and reduced emergence of parasitoid females by 77.8%. The percentage of emergence of females from pupae with the black thorax-yellow abdomen held at temperatures lower than 15°C for 20 days or more and pupae with yellow color held at 5°C for 10 or more days decreased significantly compared with females from pupae held at 25°C. Storage of pupae at 20°C or lower resulted in adult females with reduced fecundity. However, the sex ratio of the progeny was not significantly affected.