Desiccation, Flight, Glycogen, and Postponed Senescence in Drosophila melanogaster

Drosophila melanogaster selected for postponed aging have increased resistance to desiccation and increased flight duration. These and other populations were tested for longevity, flight duration, glycogen content, and stress resistance under a variety of conditions. It was found that desiccation resistance was positively associated with flight duration and glycogen content, while glycogen was exhausted in the course of desiccation, as it is in flight Flies with postponed aging also have lower water-loss rates (WLRs) when dead, suggesting that factors other than glycogen content are partly responsible for their increased desiccation resistance. However, total epicuticular hydrocarbon does not appear to determine desiccation resistance. Starvation resistance does not vary in a manner that corresponds with desiccation resistance, under either selection or manipulation, but does vary in association with lipid level This suggests at least two physiological mechanisms by which aging has been postponed in these flies: increased lipid content and increased glycogen content. These mechanisms are at least somewhat independent, evolutionarily, genetically, and physiologically.