Amplitude Of Temperature Cycle Research Articles

The cabbage moth modulates the adult eclosion time in response to the amplitude of temperature cycle

Adult eclosion rhythm of the cabbage moth, Mamestra brassicae, pupating in the soil, was recorded in darkness under two thermoperiods, 24°C (12 h):16°C (12 h) and 20.5°C (12 h):19.5°C (12 h), with different amplitude and the same average temperature. Clear daily rhythms of eclosion were observed in both conditions. However, moths eclosed about 2 h before the temperature drop in 20.5°C:19.5°C, but 4 h later in 24°C:16°C. This response to the amplitude of temperature cycle, together with similar previous observations of adult eclosion rhythms in dipterous insects, might suggest a widespread means of adaptation among insects pupating in the soil to compensate for the depth-dependent phase delay of the temperature cycle, which is the only time cue available in the soil.

The onion fly modulates the adult eclosion time in response to amplitude of temperature cycle

To confirm whether the amplitude of diel temperature cycles causes a phase shift of adult eclosion rhythm of the onion fly, Delia antiqua, the peak time (Ø(E)) of adult eclosion was determined under various thermoperiods with a fixed temperature either in the warm or cool phase and temperature differences ranging from 1°C to 4°C between the two phases. Irrespective of the temperature level during the warm or cool phase, Ø(E) occurred earlier with decreasing amplitude of the temperature cycle. The results strongly support the previous conclusion of Tanaka and Watari (Naturwissenschaften 90:76-79, 2003) that D. antiqua responds to the amplitude of temperature cycle as a cue for the circadian adult eclosion timing. The phase advance was larger in thermoperiods with a fixed warm-phase temperature than in those with a fixed cool-phase temperature. This might be ascribed to the interaction between the amplitude and level of temperature in the thermoperiodic regimes.