FEEDING, REPRODUCTIVE AND LOCOMOTOR ACTIVITIES IN DIAPAUSING AND NONDIAPAUSING ADULTS OF DROSOPHILA

Feeding, reproductive and locomotor activities of four Drosophila species were studied under short and long daylengths at 15-degrees-C. A short daylength induced firm reproductive diapause in experimental strains of D. subauraria and D. triauraria from northern Japan, but very shallow diapause in those of D. lutescens and D. rufa from southern Japan. A subtropical strain of D. triauraria had no diapause. The influence of diapause on feeding activity was detected only in aged (> 12 day old) females; that is, the feeding activity was lower in diapausing females than in non-diapausing ones. Females that do not produce eggs would not require so much energy. On the other hand, young adults of the study species exhibited a high feed activity and rapidly increased bodyweight irrespective of sex and the diapause state. They would need nutrition to build up their adult body. In males, the feeding activity decreased with age irrespective of the diapause state. Males would not require so much energy for reproductive activity. Diapausing males became heavier than non-diapausing males, perhaps because they accumulated triacylglycerols in fat bodies. However, female bodyweight did not differ by the diapause state, perhaps because diapausing females accumulated triacylglycerols and reproducing females had eggs in their ovaries. In D. triauraria, diapausing individuals exhibited somewhat lower locomotor activity than non-diapausing ones.