Termination of diapause in the larva of Lucilia caesar L. (Diptera: Calliphoridae)

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Abstract
The sheep blowfly, Lucilia caesar L., enters a facultative diapause at the end of the third larval instar immediately before puparium formation. The termination of diapause in this species, although occurring regularly over a period from 3 to 22 weeks at a constant temperature of 22 °C, was found to be accelerated significantly by exposing the diapause larvae to optimal periods of chilling at 5 °C. Suboptimal chilling periods, on the other hand, tended to prolong diapause development. The optimal requirements for diapause development were shown to be an initial chilling period of approximately 12 weeks followed by a short interval of 1–3 weeks at a temperature of 22 °C at which morphogenesis could proceed. Diapause development in L. caesar is discussed in the light of the present status of our knowledge concerning the physiological processes prerequisite to diapause termination.It has been found that the duration of diapause varies to a great extent among individual larvae, even though they are of the same parentage and subjected to the same environmental conditions. Differences also occur in the mean duration of diapause in groups of larvae from different females. It appears that these differences in diapause intensity are genetically determined.