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Journal of Experimental Biology 66,185-195 (1977)
Published by Company of Biologists 1977

Egg Diapause in Ephippiger Cruciger (Orthoptera: Tettigoniidae) : II. The Intensity and Elimination of the Final Egg Diapause

R. L. DEAN ¹ and J. C. HARTLEY ²

¹ Department of Zoology, University of Nottingham, England; Department of Zoology, University of Western Ontario, London, Canada.
² Department of Zoology, University of Nottingham, England

Unlike the initial diapause in Ephippiger crudger, the late embryonic diapause occurs in every egg in natural environmental conditions. It is eliminated by one relatively prolonged period of cooling and the proportion of eggs completing diapause development increases with increased cooling time. Diapause is most effectively eliminated through the range of 4-12°C over a period of 3-4 months. The optimal hatching temperature is lower than the optimal pre-diapause developmental temperature. There is evidence to show that although diapause development and post-diapause development can both proceed at some temperatures, a period of more intense cooling accelerates the processes. The intensity of diapause is not affected by the duration of exposure to high temperature prior to cooling. A comparison between the initial diapause and the second diapause is presented which suggests that the two types of diapause are alternative solutions to the same environmental problem.