The Effect of Age, Sex and Diapause on Desiccation Tolerance in Drosophila triauraria (Diptera, Drosophilidae)

In Drosophila triauraria, the survival time under desiccated conditions was generally longer in young flies than in old ones, in females than in males, and also in diapausing individuals than in nondiapausing ones at older ages. Water content was high at the early adult stage and decreased with age. It is assumed that young flies retain excess water and therefore tolerate desiccation. On the other hand, the difference in desiccation tolerance between the sexes seems to be due to the difference in the rate of water loss. Since females were larger than males (therefore they have a smaller surface-tovolume ratio), they would lose water more slowly and hence survived longer. The rate of water loss was also lower in diapausing individuals than in nondiapausing ones. The mechanisms for reduction of water loss in diapausing individuals were discussed in relation to cuticular hydrocarbons and metabolic rate.