Effect of temperature-fall on reproductive diapause in Drosophila sordidula and D. lacertosa

In Drosophila sordidula , critical photoperiod of reproductive diapause was longer when flies were transferred from 18 to 15 degree C at the time of eclosion than when they were maintained at 15 or 18 degree C throughout their entire lives. In D. lacertosa , the temperature-fall from 18 to 15 degree C also somewhat prolonged critical photoperiod.