Susceptibility of Immature Trichogramma pretiosum1 to Freezing and Subfreezing Temperatures 23

Abstract
Vanous ages of immature Trichogramma pretiosum Riley which were reared at 26.7°C were exposed to 0°, −5°, −10°, −15°, and −20°C. Mortality of 2-, 3-, and 4-day-old immatures was generally similar at all temperatures. The one day olds were more tolerant than the other age groups of −5° and −10°C. The 6 and 8 day olds were more susceptible to −10°, −15°, and −20°C; however, the 8 and especially the 6 day olds were more tolerant of 0°C. A predictive model was developed for mortality of immature T. pretiosum as a function of exposure time and temperature.