Does dietary restriction really increase longevity in Drosophila melanogaster?

It is often accepted that dietary restriction (DR) increases longevity in most species so far tested. Showing the same result in the fruit fly Drosophila melanogaster would be of interest, because this species is widely used in aging research. Some studies have shown that dietary restriction decreases longevity in this species while the opposite result has also been reported. However, some recent results appear to be flawed due to the use of not optimal control rearing conditions. It is argued that, for the time being, it cannot be concluded that dietary restriction increases longevity in D. melanogaster. It has also been shown in other fly species that dietary restriction does not increase longevity.