Activity patterns ofChironomus yoshimatsui (Diptera: Chironomidae)

The activity patterns ofChironomus yoshimatsui were investigated experimentally to clarify whether temperature conditions experienced by the larvae and adults had an effect on the timing of adult activities. It was observed that when both larvae and adults were reared at a low temperature of 13°C, the peak of adult evening activities appeared just before simulated nightfall whereas when larvae and/or adults were reared at a high temperature of 23°C, the peak of activities occurred just after simulated night-fall. These results agreed well with field observations of seasonal changes in the timing of evening swarming and mating of this insect. The mechanism of regulating the timing of activities in accordance with temperature conditions is also discussed.