Journal of Comparative Physiology A

, Volume 155, Issue 1, pp 1–12

Mosquito circadian and circa-bi-dian flight rhythms: a two-oscillator model

  • Joe R. Clopton

DOI: 10.1007/BF00610925

Cite this article as:
Clopton, J.R. J. Comp. Physiol. (1984) 155: 1. doi:10.1007/BF00610925


Circadian rhythmicity was found in the flight activity ofCuliseta incidens recorded in constant darkness for up to 14 weeks. The first nonhuman circa-bi-dian (about-two-day) rhythms were also found (Figs. 6–7). Circadian periods were either stable, remaining <24h (Fig. 1), or labile, with a change from <24h to >24 h (Fig. 2). Inactivity phenomena (‘day-skipping’) were common in the latter group only (Fig. 5). The period at activity onset was much more labile than the period at offset (Fig. 4). The activity patterns of some period-lengthened animals suggested control by two oscillators which could temporarily or permanently uncouple (Figs. 8–9).

A pacemaker model consisting of a labile evening (E) oscillator mutually coupled to a stable morning (M) oscillator is the most economical proposal which can account for these results. The view that E and M uncouple and run with different periods can account for many records in which the period was labile. Circa-bi-dian rhythms can be explained by the period of E lengthening to where it synchronizes with M in a 2∶1 mode. Thus, E and M are proposed to behave similarly to the human activity and temperature oscillators. It is speculated that day-skipping might indicate that E oscillates between circadian and circa-bi-dian ranges without overt activity being expressed.



alternating 12h light, 12h dark


constant dark


constant light


period of rhythm


period at activity onset


period at activity offset


activity time

\(\bar \alpha \)

mean activity time

Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Joe R. Clopton
    • 1
  1. 1.Biology DepartmentSonoma State UniversityRohnert ParkUSA
  2. 2.Life Sciences DepartmentSanta Rosa Junior CollegeSanta RosaUSA