REARING THE CABBAGE MAGGOT WITH AND WITHOUT DIAPAUSE

Abstract

Data presented demonstrate that induction of pupal diapause in the cabbage maggot,Hylemya brassicae(Bouché), involves a relationship between photoperiodic, temperature, and light intensity conditions provided for the flies, eggs, and larvae. Generally, a short daylength of 12 hours for the flies induces pupal diapause, whereas a 16-hour photoperiod dictates continuous development without diapause. However, the expected response can he partially or almost completely reversed depending upon, conditions of photoperiod and temperature provided for eggs and larvae. Decreasing temperatures combined with low light intensities and short photoperiods for flies and larvae cause almost all pupae to enter diapause, and high temperatures tend to offset the influence of a short daylength or a downward trend in photoperiodic exposures provided for the flies and larvae. Diapause development proceeds to completion at a wide range of temperatures but high levels at certain times result in high mortality. Growth development following the completion of diapause development is inhibited by temperatures above 22 °C, whereas the final or adult developmental stage continues to completion at an increasing rate with increasing temperatures.