Age, sex, adult and larval diet shape starvation resistance in the Mediterranean fruit fly: an ecological and gerontological perspective

Nikos T Papadopoulos,James R Carey,Petros Damos,Christos D Gerofotis,Christiana Koukougiannidou,Dimitris S Koveos,Nikos A Kouloussis

doi:10.1038/s41598-019-47010-0

Abstract

The ability of an animal to withstand periods of food deprivation is a key driver of invasion success (biodiversity), adaptation to new conditions, and a crucial determinant of senescence in populations. Starvation resistance (SR) is a highly plastic trait and varies in relation to environmental and genetic variables. However, beyond Drosophila, SR has been studied poorly. Exploiting an interesting model species in invasion and ageing studies-the Mediterranean fruit fly (Ceratitis capitata)- we investigated how age, food and gender, shape SR in this species. We measured SR in adults feeding in rich and poor dietary conditions, which had been reared either on natural hosts or artificial larval diet, for every single day across their lifespan. We defined which factor is the most significant determinant of SR and we explored potential links between SR and ageing. We found that SR declines with age, and that age-specific patterns are shaped in relation to adult and larval diet. Females exhibited higher SR than males. Age and adult diet were the most significant determinants of SR, followed by gender and the larval diet. Starvation resistance proved to be a weak predictor of functional ageing. Possible underlying mechanisms, ecological and gerontological significance and potential applied benefits are discussed.

Highlights

All life processes and physiological events expend energy to function
Starvation resistance (SR) decreased with age for both sexes in medflies kept in full adult diet (Fig. 1a)
Our results demonstrate that (a) SR differentially changes with age in relation to other variables, (b) diet restricted adults are more tolerant to starvation than individuals kept in adult full diet, (c) females are more tolerant than males, (d) all the tested factors have significant effects in shaping SR but of a different magnitude, (e) SR assays may provide insights into the onset of functional ageing in organisms

Summary

Introduction

All life processes and physiological events expend energy to function. A continuous supply of energy is necessary for an animal to survive and reproduce[1]. Differences in SR among individuals/populations may arise from heritable genetic variation and/or as a result of a phenotypic plasticity evoked by environmental variables Such factors (genetic and environmental) operate at the same time to shape an animal’s SR. Females are expected to withstand more food limitation than males and this is usually correlated to their larger body size and to differential energy demands, acquisition and utilization of nutritional resources between the two sexes (as discussed in[15]) This pattern is not always the same and researchers conclude that differences in SR between the two sexes vary considerably in relation to factors such as nutrition[12], social interactions (e.g. mating)[16], strain[17] and age[18,19]. To make realistic predictions on how SR is shaped and to identify the most significant factors we need studies that consider multiple variables across an animal’s lifespan

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Results

Conclusion