Effect of temperature on the life cycle of Lydella jalisco (Diptera: Tachinidae), a parasitoid of Eoreuma loftini (Lepidoptera: Pyralidae)

Abstract

The effect of temperature on development, survival, and adult longevity of Lydella jalisco Woodley (Diptera: Tachinidae), a parasitoid of the Mexican rice borer, Eoreuma loftini (Dyar) (Lepidoptera: Pyralidae), was studied under laboratory conditions. Development times of L. jalisco larvae and pupae decreased with temperatures in the range 15-35°C. However, survival was greater at cooler temperatures similar to those encountered in the parasitoid's native habitat; percentage of adult emergence was 62.5% at 20°C compared with 9.5% at 35°C. The lower temperature threshold for development of larvae was 14.5°C, whereas for pupae it was 13.8°C. Adult lifespan was also affected by high temperatures. Adult parasitoids lived 20 to 25 d at temperatures in the range 15-25°C, whereas they lived 4 to 6 d at 35-40°C. For <10 consecutive hours, temperatures exceeding 30°C prevail in the Lower Rio Grande Valley of Texas during the months of May through September when populations of E. loftini reach an economic threshold. Therefore, the potential efficacy of L. jalisco as a biological control agent of E. loftini in south Texas should be examined closely because mated females of L. jalisco require 7-14 d for maximum egg fertilization and embryonic development.