Morphological, physiological and behavioural evidence for sonic signals in the sexual communication system of lymantriid moths

Sexual communication of gypsy moth, Lymantria dispar (L.), nun moth, L. monacha (L.), pink gypsy moth, L. mathura (M.), and fumida tussock moth, L. fumida (B.) is known to be mediated by pheromones. Data presented here show that sonic and visual signals are also involved. Sound produced by flying male L. dispar induced wing-fluttering and motion in conspecific females that may guide males to their micro-location. Analyses of sounds produced by wing fanning L. monacha, L. mathura, and L. fumida revealed species- and sex-specific wing beat and associated click frequencies that may contribute to reproductive isolation or close-range communication. Evidence for close-range communication in these lymnatriids includes (i) scanning electron micrographs of functional metathoracic tympanate ears, (ii) attraction of male L. monacha and L. fumida to speakers playing back sound signals from conspecific females, and (iii) laser interferometry demonstrating particular sensitivity of tympana to frequency components of conspecific sound signals.