Article

Ecdysones and imaginal disc development during the last larval instar of Pieris brassicae.

Ecole Normale Supérieure, Laboratoire de Zoologie, 46 rue d'Ulm, F-75230 Paris Cedex 05, France
Journal of Insect Physiology (Impact Factor: 2.38). 02/1977; 23(2):277-83. DOI: 10.1016/0022-1910(77)90042-7
Source: PubMed

ABSTRACT Ecdysone haemolymph levels and in vivo development of imaginal wing discs have been studied during the last larval instar of Pieris brassicae.During this period, β-ecdysone variations show two successive peaks, the first one related to the induction of wandering stage, and the second (main) one to pupal cuticle synthesis. The observed situation is very similar to that of Manduca sexta. Imaginal wing disc growth is composed of several genetically programmed steps that need the presence of ecdysone, but do not appear very closely linked to circulating hormone levels. It seems that ecdysone haemolymph peaks should be considered as periods where ecdysone levels are above a threshold value.

0 Bookmarks
 · 
55 Views
  • [Show abstract] [Hide abstract]
    ABSTRACT: The rate of DNA synthesis of wing discs and the effects of X ray irradiation and mitomycin C injection were observed during last larval and early pupal stage of Bombyx mori. The rate of DNA synthesis in wing discs of Bombyx mori was estimated by means of the incorporation of 3H-thymidine during the fifth larval stage. Mitomycin C injection and X ray irradiation were performed during the fifth larval instar and pupal stage to investigate the effects of inhibition of DNA synthesis. The rates of 3H-thymidine incorporation were high on days 0, 1, 2, 4, 5, 7, 8 and 10 of the fifth larval instar. Wings of eclosed adults were affected by injections of mitomycin C between the 7th day of the fifth larval instar and the second day of the pupal stage. Exposing the insects to X rays during the fifth larval instar affected wing and scale formation, and at earlier stages, it had a more deleterious effect. Irradiation at 24–36 hours after pupation inhibited wing expansion and scale formation most among pupal stages. The results suggested that the peaks of 3H-thymidine incorporation during the fifth larval instar and the pupal stage have specific significance for wing development.
    ZOOLOGICAL SCIENCE 01/2009; · 1.08 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: In the eri-silkworm, Samia cynthia ricini, the adult antennal flagellum is segmented into many annuli. Although the number of annuli is an important parameter in the morphogenesis of adult antenna, it is not clear when and how the number of annuli is determined. In the present study the fifth instar larva of the eri-silkworm was studied histologically to clarify when the antennal imaginal disk began morphogenesis and when the number of annuli of adult antennal flagellum was determined. In addition we studied whether the length of the embryonic and larval period might have any influence on the number of annuli in the erisilkworm, and the influence of other factors such as body size and sex was also examined. Serial histological study of the imaginal disk during the larval period suggested that the number of annuli was determined by the second day after gut-purging, since the segmentation of the pupal antenna was almost finished by this time and the number of segments of pupal antenna was nearly equal to the number of annuli of adult antenna. The embryonic and larval period was closely related with the number of annuli. When the insects were reared at 25°C, the number of annuli was almost equal to the number of the days in which the insects passed from oviposition to gut-purging. In addition, the number of annuli tended to increase one by one from 27 to 34 as the embryonic and larval period was extended day by day from 28 to 35 days. When the insects were reared at 18°C, the larval period was doubled, whereas the number of annuli remained in the same range (28–34) as that reared at 25°C. The body size did not correlate with the number of annuli. Although the number of annuli was significantly larger in female than in male, this difference seemed to be due to the difference in the length of the embryonic and larval period in both sexes.
    ZOOLOGICAL SCIENCE 01/2009; · 1.08 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: In animals with complex life cycles, all resources needed to form adult tissues are procured at the larval stage. For butterflies, the proper development of wings involves synthesizing tissue during metamorphosis based on the raw materials obtained by larvae. Similarly, manufacture of pigment for wing scales also requires resources acquired by larvae. We conducted an experiment to test the effects of food deprivation in the larval stage on multiple measures of adult wing morphology and coloration of monarch butterflies (Danaus plexippus), a species in which long-distance migration makes flight efficiency critical. In a captive setting, we restricted food (milkweed) from late-stage larvae for either 24 hrs or 48 hrs, then after metamorphosis we used image analysis methods to measure forewing surface area and elongation (length/width), which are both important for migration. We also measured the brightness of orange pigment and the intensity of black on the wing. There were correlations between several wing features, including an unexpected association between wing elongation and melanism, which will require further study to fully understand. The clearest effect of food restriction was a reduction in adult wing size in the high stress group (by approximately 2%). Patterns observed for other wing traits were ambiguous: monarchs in the low stress group (but not the high) had less elongated and paler orange pigmentation. There was no effect on wing melanism. Although some patterns obtained in this study were unclear, our results concerning wing size have direct bearing on the monarch migration. We show that if milkweed is limited for monarch larvae, their wings become stunted, which could ultimately result in lower migration success.
    PLoS ONE 01/2014; 9(4):e93492. · 3.73 Impact Factor