Effects of temperature on immature development of the parasitic fly Bessa parallela (Meigen) (Diptera: Tachinidae)

Laboratory experiments were designed to determine the effects of four constant temperatures (15, 20, 25, and 30°C) on immature development of the gregarious larval parasitoid, Bessa parallela, using Pieris rapae crucivora as a host. The developmental rate from oviposition to adult emergence increased with increasing temperature. The lower developmental threshold from oviposition to adult emergence was 8.0°C for females and 7.5°C for males. The total effective temperature from oviposition to adult emergence was 333.3 degree-days for females and 250.0 degree-days for males. We estimated that B. parallela could have nine generations at most per year in Fukuoka City. Immature survival was not influenced by temperature, but the adults emerged at 30°C tended to have smaller body size than those at the lower temperatures.