Male-female courtship assay

To test male-female courtship behavior, we used 5–7-day old virgin male flies and 3–5-day old virgin female flies. Both males and females were reared in single-sex groups. The male-female courtship chamber (30mm diameter and 3mm height) was designed based on a previous report (^{Simon and Dickinson, 2010}). The freely interacting male and female flies were illuminated by an IR light (Back-lit Backlights, BL1212, Advanced Illumination). To avoid heating, the arena was equipped with a liquid cooling system (Exos-2 Liquid Cooling System, EX2-750BK, Koolance). Courtship behavior was recorded at 30fps using a FLIR Blackfly-S camera (BFS-U3-31S4M-C, Monochrome) equipped with an IR filter (Edmund Optics, IR Pass Filter, R-72). The recordings lasted for 60 minutes or until successful copulation.