The effect of rearing temperature on parasitism by Trichogramma sibericum Sorkina at ambient temperatures

Parasitism activity of Trichogramma sibericum Sorkina tested in laboratory bioassays at different ambient temperatures was not dependent on the rearing temperature of the wasps. Trichogramma sibericum parasitized more Ephestia kuehniella Zeller eggs as ambient temperature increased from 16 to 26 °C. Rearing temperature had a significant effect on potential fecundity (measured as egg load) and on parasitism rate. Insects reared at 21 °C laid significantly more eggs than wasps reared at 16, 26 °C or fluctuating temperatures between 16 and 26 °C. Computer generated simulations with laboratory derived data suggest that rearing T. sibericum at 16 °C will improve biological control efficacy when ambient temperatures are expected to be cool (<20 °C). Marginal analysis also indicates that rearing at 16 °C is more cost effective, again when ambient temperatures are expected to be cool.