Answer:
above 25°C it will curl. in between 25°C and 16°C it will curl a little bit. below 16°C it will be straight.
Extra info on The wings of fruit fly:
Some fruit flies are born with curly wings which makes them unable to fly. It has been shown that curly wings are caused by a dominant gene which can be represented by the symbol W, while the recessive normal wing gene is represented by the symbol w. If a parent fly with the genotype WW is crossed with a parent of the genotype Ww, 100% of the offspring will have curly wings.