), immobilized the wings of one randomly assigned female and recorded the number of alighting responses by males on or near each female.Significantly more alighting responses by males on or near females that could move their wings than on females that could not (mean ± SE: 34.10 ± 3.76 vs.In both experiments, the female or male fly exposed to pulsed light (190 Hz) received many more alighting responses (mean ± SE) by males than did the fly illuminated by constant light (Exp. Only then would a male fly be able to distinguish between rival males and prospective mates traversing his territory.
Occupying vantage points in their territories, males survey rapid fly-bys of females and males, and then decide whether to fend off rival males or pursue prospective female mates.
The design and processing speed of the flies’ compound eyes allow us to infer functional linkage  of the visual communication signals that females send and males perceive.
Flies have some of the most elaborate visual systems in the Insecta, often featuring large, sexually dimorphic eyes with specialized “bright zones” that may have a functional role during mate-seeking behavior.
The fast visual system of flies is considered to be an adaptation in support of their advanced flight abilities.
Here, we show that the immense processing speed of the flies’ photoreceptors plays a crucial role in mate recognition.
, under direct light at 15,000 frames per second revealed that wing movements produce a single, reflected light flash per wing beat.a–d Photographs in the upper row reveal changes in the intensity of light reflected off the wing as it rotates during wing fanning, thus causing a flashing light effect in b; e–h Photographs in the lower row fail to reveal any flashing light effect.wings mounted on hemostatic clamps and exposed to diffuse sunlight (a) and direct sunlight (b-f) on a day with periods of sunshine and clouds.In the absence of phenotypic traits of female flies, and when given a choice between light emitting diodes that emitted either constant light or light pulsed at a frequency of 110, 178, 250, or 290 Hz, males show a strong preference for the 178-Hz pulsed light, which most closely approximates the wing beat frequency of prospective mates. The system depends upon the sex- and age-specific frequencies of light flashes reflecting off moving wings, and the ability of male flies to distinguish between the frequency of light flashes produced by rival males and prospective mates.Our findings imply that insect photoreceptors with fast processing speed may not only support agile flight with advanced maneuverability but may also play a supreme role in mate recognition.In sub-panels b–f, note the bright sunlight reflected off the right wing in each pair : Figure S1a), one that produced light pulses at 190 Hz approximating the wing flash frequency of a flying female, and the other that produced constant light at the same intensity.