| Summary: | 碩士 === 國立臺灣大學 === 昆蟲學研究所 === 93 === Endogenous circadian clock is the timing device that insects use to anticipate the daily environmental changes. The traditional way to understand the phase changes of the circadian clock is to obtain long continuous data (at least 10 days worth of observation on locomotion) or a population data (such as timing of adult emergence). The circadian phase, then, can be known by calculating the data after the experiments. To shorten the long experimental time or an urgent need to know the phase, a rapid method to reveal the phase for the exact individual is an ideal way for the application of the knowledge of circadian clock. Adult males of the German cockroaches (Blattella germanica) express circadian rhythm in locomotion. Although adult females’ locomotor circadian rhythms are masked by the developing ovary, their circadian clocks are running and can be expressed in other overt rhythms. Since electroantennogram (EAG) is a quick, sensitive and a relatively non-intrusive method to monitor the phase of the circadian clock, the purpose in this study is to establish a basic reliable circadian pattern of EAG that corresponds to the overt rhythm of locomotion. Adult male German cockroaches have circadian rhythm of neuron activity in olfactory response by measuring EAG. By using ethyl acetate as the stimulus, the amplitude of EAG response fluctuates under constant darkness or light-dark cycle. The peak of response was at the subjective night. However, the EAG responses of adult females are arrhythmic. Dilution-responded curves of EAG indicate that waveforms of EAG response are similar when stimulated by different concentrations of ethyl acetate. The result indicates that adult males expressed EAG circadian rhythm and the masking effects on female’s locomotion may hinder the measurement of EAG response.
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