TRADE-OFF IN ALLOCATION OF METABOLIC RESERVES - EFFECTS OF DIAPAUSE ON EGG-PRODUCTION AND ADULT LONGEVITY IN A MULTIVOTINE BRUCHID, KYTORHINUS-SHARPIANUS

1. In some overwintering insects, several authors have suggested a trade-off in the allocation of metabolic reserves between diapause maintenance and post-diapause reproduction. To investigate this trade-off, the diapausing larvae of the bruchid Kytorhinus sharpianus were exposed to various periods of chilling (5 degrees C) and we examined changes in egg production and adult longevity after the termination of chilling. 2. A relatively long period of chilling during diapause increased both the incidence acid rate of diapause termination. 3. Long periods of chilling reduced egg production, and increased the preoviposition period, but they also increased the longevity of adults that had not fed. When the adults fed on sugar and water, the post-diapause females that had experienced 50 days chilling had significantly longer preoviposition periods and longevity than non-diapause ones but a significant difference was not seen in their egg production. 4. We discussed the physiological mechanism causing this phenotypic difference between the diapausing and non-diapausing generations by the double trade-offs in the allocation of metabolic reserves not only between diapause maintenance and reproduction but also between longevity and reproduction.