Longevity of Cosmopolitan and Native Australian Drosophila in Ethanol Atmospheres.

Abstract

The longevity of adults exposed to ethanol vapour over solutions of ethanol in water is increased in Drosophila species that are normally collected by attraction to fermented-fruit baits. These include species of subgenera Drosophila, Dorsilopha, Sophophora and Scaptodrosophila. The increase occurs up to a threshold where ethanol becomes a metabolic cost rather than a benefit. Except for a temperatezone population of D. melanogaster with a threshold of about 12%, the remainder cluster between 1.6 and 5.1%. These latter include several species utilizing resources additional to fruits, in particular various vegetables and flowers. Also included is the specialist species D. buzzatii which exploits the cactus Opuntia as a resource. In contrast, D. (Scaptodrosophila) inornata, a species collected by sweeping in southern temperate rain forests, has a threshold of <1% ethanol, while in D. (Scaptodrosophila) hibisci, which utilizes endemic Hibiscus flowers as a resource, longevity is not increased. The frequency and level of ethanol resource utilization in species not attracted to fermented-fruit baits is an open question. However, it is likely that all species attracted to fermented-fruit baits are able to utilize gaseous ethanol.