Diet Shapes Mortality Response to Trauma in Old Tephritid Fruit Flies.

James R Carey,Cong Xu,Yu-Ru Su,Hans-Georg Müller,Pablo Liedo,Jane-Ling Wang,James W Vaupel

doi:10.1371/journal.pone.0158468

Abstract

Despite the importance of trauma in healthspan and lifespan in humans as well as in non-human species, with one important exception the literature in both gerontology and ecology contains virtually no experimental demographic studies concerned with trauma in any species. We used dietary manipulation [full diet (F) versus sugar-only (S)] to produce four levels of frailty in 55-day old tephritid fruit flies (Anastrepha ludens) that were then subject to the trauma of cage transfer stress (n = 900/sex in each of the 4 treatments). The key results included the following: (1) there is a trauma effect caused by the transfer that depends on previous diet before transfer, new diet after transfer and gender of the fly; (2) males are more vulnerable than females; (3) if initial diet was F, flies are relatively immune against the trauma, and the subsequent diet (F or S) does not matter; (4) however if initial diet was S, then the effect of the trauma depends largely on the diet after the transfer; (5) flies transferred from S to F diets do very well in terms of remaining longevity (i.e. greatest remaining longevity), while flies transferred from S to S diet do poorly (i.e. shortest remaining longevity). We discuss both the strengths and weaknesses of this study and implications of the results.

Highlights

Despite the importance of accidents and trauma among the elderly [1] and the increased use of model organisms for studies on healthspan [2,3] including studies on the effects on longevity of injury and stress on aging in fruit flies [4,5,6], it is remarkable that so few studies concerned with healthspan have been conducted on trauma in these [7] or any other invertebrates
We find that all parameters in the Model 1 are positive and highly significant (Table 2), except for diet 2 after transfer, pointing to the presence of short-term trauma effects on subsequent mortality
A large literature exists on the effects on mortality in fruit flies of various types of stressors such as desiccation and starvation [4,8] and of mechanical impairments [9], ours is only the second controlled study we are aware of that documents the immediate consequences of acute trauma [7] in any organism and the only study which did so for the effects of trauma on the remaining life expectancy

Summary

Introduction

Despite the importance of accidents and trauma among the elderly [1] and the increased use of model organisms for studies on healthspan [2,3] including studies on the effects on longevity of injury and stress on aging in fruit flies [4,5,6], it is remarkable that so few studies concerned with healthspan have been conducted on trauma in these [7] or any other invertebrates. We recorded daily survival during the entire post-transfer period but divided the analysis into two parts including short term survival (i.e. the post-transfer survival response during the first six days to quantify the severity of the acute trauma) and long term survival (including all remaining lifetimes after transfer). We used these results to address the following sets of questions: (1) How does trauma shape gender-specific mortality in older flies of different frailty levels and what role does diet play?

Methods

Results

Conclusion