The Circadian Clocks of Insect Eclosion
Understanding the circadian timing of eclosion in insects is a pretty big undertaking. A lot of technical detail is essential and a lot of close reasoning from meticulous experiments stands in the place of direct observations on the “clock’s” unknown physiological mechanism. In that respect clockology has some of the intellectual delight of the earlier years of genetics. However, (as of the 1978 writing) the whole argument has never been spelled out for publication in one place. This chapter once again attempts only an outline of the essentials. The story presented here seems to be generally valid for butterflies and moths, flies and mosquitoes, wasps and bees (i.e., Lepidoptera, Diptera, and Hymenoptera), but I emphasize my own experimental beast, the fruitfly. For a review of insect eclosion systems from the viewpoint of physiology and ecology, see Remmert (1962).
KeywordsLight Pulse CiRCADIAN Clock Dark Adaptation Temperature Pulse Stimulus Magnitude
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- 2.In 1967, I was using ethyl methane sulfonate, a gift from Seymour Benzer, to make mutants, but never found an interesting one. Ron Konopka (1972) produced per s and others, and kindly provided them to me for pupal eclosion experiments.Google Scholar
- 3.Chandrashekaran and Engelmann (1973) suggested replacing this smooth function by a stepwise increase in photosensitivity with steps at each T*. That would produce a tear in the resetting surface, an edge dislocation in the time crystal. I see no such tear in my Figure 5.Google Scholar
- 4.In the more recent notation of Pittendrigh and Daans’ five major papers of 1976, “continuous action” equals “parametric” and means duration has a continuing conspicuous effect on the phase shift, while “differential response” equals “nonparametric” and means that beyond a short time after abrupt light onset duration has little further consequence.Google Scholar
- 5.As with most other innovations, one could point to earlier independent discoverers: Kalmus and Wigglesworth (1960); Wever (1962–3-4); Moshkov et al. (1966) applied the same ideas in the same format to circadian rhythms in general, but they failed to pin this model explicitly to one data set. Strahm (1964) (cited only in Pavlidis, 1967a) had all the essentials, applied specifically to D. pseudoobscura but he neglected to publish after submitting his thesis (see Chapter 7, Box A).Google Scholar