AJP - Regulatory, Integrative and Comparative Physiology, Vol 247, Issue 6 960-R967, Copyright © 1984 by American Physiological Society
Mosquito circadian flight rhythms: differential effects of constant light
J. R. Clopton
The flight activity of Culiseta incidens was automatically recorded in
constant darkness and constant light after entrainment to light:dark 12:12
to determine the usefulness of a formal circadian pacemaker model in which
the periods of two oscillators respond reciprocally to light intensity.
Period at activity onset lengthened approximately 0.4 h from darkness to
0.1 lx, whereas period at offset shortened approximately 0.4 h. Thus within
this range, the onset of the nocturnal active phase obeyed Aschoff's rule
for nocturnal animals, and the offset (or onset of diurnal rest phase)
obeyed the rule for diurnal animals. These data supported a model in which,
as light intensity increases, the period of one oscillator (evening)
increases while that of another (morning) decreases. This model, with
additional assumptions, also provided a framework for mutually consistent
explanations of other features among the data. These included long periods
at 3.5 lx, short periods at 35 lx, a progressively earlier occurrence of
inactivity with increasing light intensity, and a clear example of
circa-bi-dian (approximately 2 days) rhythmicity.
