SEASONAL-CHANGES IN GLYCOGEN AND TREHALOSE CONTENT IN RELATION TO WINTER SURVIVAL OF 4 TEMPERATE SPECIES OF DROSOPHILA

Trehalose was the major sugar found in adult flies of four temperate species of Drosophila (D. subauraria, D. triauraria, D. rufa and D. lutescens) and its level rose in early winter and gradually declined thereafter. Low temperature facilitated trehalose synthesis in these species, but the diapause state did not affect the synthesis, at least in the cool-temperate species (D. subauraria and D. triauraria). In diapausing individuals of these cool-temperate species, glycogen content remained rather high even in mid-winter, but declined to low levels by spring. By contrast, the warm-temperate species (D. rufa and D. lutescens) and the non-diapause strain of D. triauraria exposed to a cool-temperate climate lost more than half of their stored glycogen by mid-winter and they did not survive to the spring. It is concluded therefore that glycogen level plays a part in winter survival in these Drosophila species.