Longevity, Resource Utilization and Larval Preferences in Drosophila: Inter- and Intraspecific Variation.

On the basis of life-span, the threshold ranking at which ethanol and acetic acid ceased to be resources and became stresses for 3 sympatric, cosmopolitan Drosophila species was: D. melanogaster Mg. > D. simulans Sturt. > D. immigrans Sturt. The threshold ranking between larval attraction and avoidance followed the same sequence. An Adh-null mutant of D. melanogaster utilised ethanol to an extremely low threshold, while acetic acid was utilised to a threshold close to that of the D. melanogaster population; this predictable result was paralleled by larval attraction to acetic acid but not ethanol. It can therefore be concluded that there is an association between biochemical and behavioural phenotypes relating to resources commonly available in nature. Acetic acid acts as an attractant to larvae of all species at concentrations down to 1/1000 of the concentrations of ethanol attracting flies, which suggests that acetic acid may be a resource recognition compound, as well as a food resource.