Life extension in Drosophila maintained under lengthened light/dark regime.

In the present study, we investigated whether the length of light/dark cycle could influence the pre-adult developmental time and adult life span in Drosophila melanogaster. Flies were reared to adulthood and maintained as adults under both 24-h (light/dark 12:12 h) and 48-h (light/dark 24:24 h) cycles. The flies reared during pre-adult stages at the 48-h light/dark cycle had significantly prolonged developmental time compared to those in flies reared at normal 24-h cycle. Irrespective of the duration of pre-adult light/dark period, the males maintained as adults at prolonged 48-h cycle had a 13-16% longer mean adult life span than those maintained at normal 24-h cycle (P<0.001 in all cases). In females reared under normal 24-h cycle such differences were lower but also significant (P=0.03); no significant difference in life span was found in females reared under prolonged 48-h cycle. The results are interpreted to demonstrate that pre-adult developmental time and adult life span in Drosophila melanogaster are both influenced by the length of light/dark cycle.