Sound production by abdominal tymbal organs in two moth species: The greensilver-line and the scarce silver-line (Noctuoidea : Nolidae : Chloephorinae)
N. Skals et A. Surlykke, Sound production by abdominal tymbal organs in two moth species: The greensilver-line and the scarce silver-line (Noctuoidea : Nolidae : Chloephorinae), J EXP BIOL, 202(21), 1999, pp. 2937-2949
Male moths of the chloephorine species Pseudoips prasinana and Bena bicolor
ana produce clicks (approximately 100 dB peSPL at 10cm) using ventral tymba
l organs located in a cleft in the second abdominal sternite. Large muscles
insert on the dorsal part of the tymbal frame and rhythmically flex a thin
sheet of cuticle. Normally, each sound-production cycle contains four clic
ks, the left and right tymbals producing clicks both on active buckling cau
sed by muscle contraction and on the passive elastic return from buckling.
Histochemical staining indicated the presence of elastic resilin-like prote
ins in the tymbals, Obvious differences between the click patterns of the t
wo species reflect differences in their tymbal morphology. P. prasinana has
smooth tymbals and produces a single click (300 mu s, 40kHz) for each tymb
al buckling, In contrast, B. bicolorana has striae on the medial part of th
e tymbals, Accordingly, it produces many clicks per buckling. The click pat
tern is a heterogeneous mixture of large clicks at 52 kHz, resembling those
of P. prasinana, interspersed with series of broad-band clicks (20-100 kHz
) of lower intensity (15-20 dB), Thus, in chloephorine moths, there is a co
rrelation between the structure and function of the smooth and striated tym
bals that is strikingly similar to that in arctiid moths, although the two
types of tymbals have evolved independently, The hearing of P. prasinana is
tuned to its own sounds with lowest threshold (38 dB SPL) at 40-60kHz. We
suggest that sound production in male chloephorines plays a part in sexual
acoustic communication.