1993 Volume 44 Issue 4 Pages 355-360
The features of acoustic response and wingbeat frequency of a chironomid midge, Chironomus yoshimatsui were studied. The swarms observed were formed above the ground close by cherry trees. The swarming males were mainly caught by cylindrical sound traps emitting sound frequencies of 180-270Hz at between 9 and 15℃ and of 300-390Hz at between 20 and 28℃ during the experimental period in a field. However, the swarming male responded to a fairly narrow range of sound frequency at an ambient air temperature. Accordingly, there was a good correlation between the air temperature and the sound frequency of the highest male catch. The sound frequency of the highest male catch changed at the rate of 10Hz/℃. The mean wingbeat frequencies of both sexes were almost at constant levels from the first day of emergence to the 4-day-old after emergence. The male wingbeat frequency was always higher than that of the female at the same air temperature. There was a good correlation between the air temperature and the wingbeat frequency of each adult day in both sexes. The wingbeat frequencies of male and female changed at the rate of 18-21 and 10-12Hz/℃, respectively. When the regression line of the female wingbeat frequency on the air temperature of each adult day is compared with that of the sound frequency of the highest male catch on the air temperature, the former is consistent with the latter statistically. This indicates that swarming male has the hearing faculty to be accurately tuned to the wingbeat frequency of conspecific female which is variable with the ambient air temperature.