Aggressive and Courtship Chirps of Sympatric Pleasing Fungus Beetles, Dacne japonica and D. picta (Coleoptera : Erotylidae)

The pleasing fungus beetles, Dacne japonica and D. picta, are pests of the shiitake mushroom, Lentinus edodes. Males of both species stridulate by scraping the files on the vertex against the ridges of the pronotum. When a male contacts another individual, he first touches the other's elytra by the maxillary palpi. If the contacted individual was a male, the palpating male ignored him and moved away or sometimes produced aggressive chirps. If the contacted individual was a female, he started another gentler chirping and tried to mount her. He kept singing this courtship chirping during copulation. The male produced the aggressive chirps also when another individual, male or female, interfered with his mating or feeding. The numbers of chirps in a bout and the numbers of syllables in a chirp were significantly different between aggressive and courtship behaviors for both species. The numbers and intervals of syllables in the courtship chirps were significantly different between the two species, whereas there were no differences in the aggressive chirps.