From: gts (gts_2000@yahoo.com)
Date: Sat Nov 30 2002 - 20:16:26 MST
Life history response of Mediterranean fruit flies to dietary
restriction
James R. Carey1 Pablo Liedo2 Lawrence Harshman3 Ying Zhang4 Hans-Georg
Müller4 Linda Partridge5 and Jane-Ling Wang4
Summary
The purpose of this study was to investigate medfly longevity and
reproduction across a broad spectrum of diet restriction using a
protocol similar to those applied in most rodent studies. Age-specific
reproduction and age of death were monitored for 1200 adult males and
1200 females, each individually maintained on one of 12 diets from ad
libitum to 30% of ad libitum. Diet was provided in a fixed volume of
solution that was fully consumed each day, ensuring control of total
nutrient consumption for every fly. Contrary to expectation and
precedence, increased longevity was not observed at any level of diet
restriction. Among females, reproduction continued across all diet
levels despite the cost in terms of increased mortality. Among males,
life expectancy exceeded that of females at most diet levels. However,
in both sexes, mortality increased more sharply and the pattern of
survival changed abruptly once the diet level fell to 50% of ad libitum
or below, even though the energetic demands of egg production has no
obvious counterpart in males. We believe that a more complete picture of
the life table response to dietary restriction will emerge when studies
are conducted on a wider range of species and include both sexes, more
levels of diet, and the opportunity for mating and reproduction.
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