Eur. J. Entomol. 94 (1): 67-73, 1997
Diapause intensity and ecdysiotroph: Comparisons between two Antheraea species (Lepidoptera: Saturniidae) having summer and winter diapause at pupae
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The photoperiodic and neuroendocrine regulations of diapause termination were investigated in two Antheraea species, A. yamamai and A. pernyi which have pupal diapause to aestivate and overwinter, respectively. The types of photoperiodic responses were inverse between the two species, a short-day type in A. yamamai and a long-day type in A. pernyi. When the diapause intensity was compared among A. yamamai and two strains of A. pernyi, the intensity in the univoltine strain of A. pernyi was the strongest, while that in A. yamamai the weakest. Although the timing of ecdysteroid release, a physiological landmark for the termination of diapause, was equivalent in A. yamamai and the bivoltine strain of A. pernyi namely after about ten cycles of exposure to a diapause-averting photoperiod, the basal levels of ecdysteroids in pupae kept in diapause-maintaining conditions were different, higher in A. yamamai than in the bivoltine strain of A. pernyi. Therefore, one correlate was found between diapause tendency and basal ecdysteroid level: the higher was the basal ecdysteroid level, the weaker the diapause tendency.
Brain monoamine contents were next investigated in A. yamamai and two strains of A. pernyi, the bivoltine and univoltine strains. Catecholamine levels, especially that of ''epinephrine'' in diapause pupae were found to correlate with the general strength of diapause, since the univoltine strain of A. pernyi had the highest level, while A. yamamai the lowest and the bivoltine strain of A. pernyi was intermediate. The result infers that high catecholamine contents may be reflected in the refractoriness of PTTH secreting pathway or low sensitivity to PTTH.
Keywords: Photoperiodism, diapause termination, diapause intensity, ecdysteroids, catecholamines, Lepidoptera, Antheraea moths
Accepted: May 20, 1996; Published: March 10, 1997 Show citation
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