An analysis of a circadian rhythm of oviposition in Oncopeltus fasciatus.

Several behavioural circadian rhythms have been described in Oncopeltus fasciatus, including daily cycles of mating, feeding, oviposition, flight, and general locomotor activity (Caldwell & Dingle, 1967; Dingle, 1968; Caldwell & Rankin, 1971). This insect is known to be migrant, and the temporal segregation of daily activities brought about by this temporal organization is adaptive in relation to its migratory strategy (Caldwell & Rankin, 1971). Mating and feeding occur primarily in the evening, beginning about 10 h after light onset, while in pre-reproductive individuals flight takes place in the afternoon between 5 and 10 h after light onset. When egg production begins, further flight is inhibited in the female, and oviposition occurs at this time (Dingle, 1968). Oviposition seemed most suitable for studying the physiological mechanisms underlying these rhythms because it is easily monitored and because one component, egg development, can be separated from another, the actual oviposition behaviour.