Non-fatal / low-harm measurement of Drosophila traits
You could do negative geotaxis (climbing) assay, (larval or adult) locomotion assays, % brain vacuolisation (after the flies die), maze tests. There are probably much more but these are all I can think of that are no-lethal and can be applied to males and females and some larval work too.

You could maybe consider doing starvation assays and longevity in some of your populations.