Fast and sexually dimorphic photoreceptors – sensory tools for mate recognition systems in horn flies and stable flies?

Male green bottle flies, Lucilia sericata, were previously found to recognize conspecific females based on the frequency with which incident light is reflected from their moving wings. We studied whether horn flies, Haematobia irritans, and stable flies, Stomoxys calcitrans, possess the physiological capabilities to utilize a similar mate recognition system. To utilize this type of mate recognition cue, males must have visual systems with temporal resolutions which exceed the frequency of female wing flashes (or wing beats). Our research objectives were to determine (1) the flicker fusion frequency (FFF) of horn and stable fly eyes in electroretinogram (ERG) recordings and (2) the wing flash frequency of male and female horn and stable flies through high-speed video recordings. Compound eyes of flies from both species had high FFFs ( >250 Hz) and for each species males had significantly higher FFFs than conspecific females. High-speed video recordings revealed that wing beat frequencies significantly differed between male and female stable flies. To ascertain whether LED lights flashing at the wing beat frequency of young stable fly females attract conspecific males requires additional rigorous testing.