Circasemilunar control of imaginal disc development in Clunio marinus: Temporal switching point, temperature-compensated developmental time and ecdysteroid profile

• Published in: Journal of insect physiology Vol. 37; no. 2; pp. 101 - 109
• Main Authors: Neumann, D., Spindler, K.-D.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 1991; Elsevier
• Subjects: aquatic insects; Biochemistry. Physiology. Immunology; Biological and medical sciences; biological development; biological rhythms; body weight; Chironomidae; circasemilunar rhythm; Clunio marinus; developmental time; Diptera; ecdysteroid profile; ecdysteroids; Freshwater; Fundamental and applied biological sciences. Psychology; Imaginal disc development; Insecta; Invertebrates; laboratory techniques; metamorphosis; Physiology. Development; temperature; Imaginal disc development; developmental time; chironomidae; circasemilunar rhythm; ecdysteroid profile; Chironomidae; Imaginal disk; Temperature; Insecta; HPLC chromatography; Environmental factor; Biological rhythm; Postembryonic development; Larva; Ecdysteroide; Arthropoda; Invertebrata; Metamorphosis; Diptera
• ISSN: 0022-1910; 1879-1611
• DOI: 10.1016/0022-1910(91)90095-H

In synchronized laboratory populations of the intertidal chironomid Clunio marinus demonstrating circasemilunar rhythms of eclosion, both imaginal disc development and ecdysteroid profile are described during the last larval instar. No circasemilunar synchronization occurred during moulting to the last larval instar and early imaginal disc development (stages 1 and 2). Circasemilunar cohorts of larvae with increasing imaginal discs and reinforced larval growth started from stage 3 of the 4th instar (at 19°C) every 15 days (morphologically observable circasemilunar switching point). They mainly passed stage 4 on days 9–13 of the semimonthly zeitgeber cycle. They reached the prepupal stage after about 11 days and emerged a few days later on days 10–12 of the following semimonthly cycle, i.e. about two weeks from stage 4 onwards. Between stages 1–9 a 260% increase in the body weight occurred at 19°C and even 420% occurred at 11°C. Within this temperature range, both the developmental time and the rate of imaginal disc development were temperature-compensated between the circasemilunar switching point and pupation. The ecdysteroid contents of stages 1–7 of the last larval instar were generally low (140–250 ng ecd. equiv. g −1 dry wt). They increased to about 640 ng during the prepupa, and to 1330 ng during the early pupal stage. In advance of the switching point, a pronounced small rise in the ecdysteroid contents of the whole larva was observed in only some samples of stage 2, but this was always in an appropriate temporal correlation with the switching point on days 2–5 of the semimonthly zeitgeber cycle. The results are discussed with regard to the temporal programming of metamorphosis by a developmental modulator factor which in the case of Clunio is under the control of the circasemilunar clock mechanism.