抄録
Temporal parameters of male courtship songs produced by wild (W-), mass-reared (M-), and by irradiated (I-) strains of Dacus cucurbitae COQUILETT were examined. The pulse-train duration (PTD), the pulse-train interval (PTI), and the pulse-train period (PTP) that appeared during calling and courtship sounds were measured. Only the PTI showed leptokurtic distribution, and appeared to be concentrated within 0.10-0.30 sec compared to the PTD and the PTP. The peak of the average block occupation rates of the PTI was 0.15-0.20 sec in the M- and I-strains (except for age 32 days), and 0.15-0.20 sec for ages 22 and 32 days and 0.20-0.25 sec for ages 17 and 27 days in the W-strain. In the M- and I-strains 69-94% of the highest two peaks of the total PTI were 0.10-0.25 sec long, but in the W-strain (except for age 22 days) 85-92% of those were 0.15-0.30 sec long. The laboratory-reared strains shortened their PTI by 0.05 sec compared to that of the wild strain. The concentration of the PTI values may be due to the PTI being a cue for attracting females. The presence of temporal difference in the PTI between the wild and laboratory-reared strains explains it to be an effective parameter for the estimation of qualitative characteristics.
