Exposure to light enhances pre-adult fitness in two dark-dwelling sympatric species of ants

Shahnaz Rahman Lone,Vijay Kumar Sharma

doi:10.1186/1471-213x-8-113

Shahnaz Rahman Lone, Vijay Kumar Sharma

Open Access

https://doi.org/10.1186/1471-213x-8-113

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Abstract

BackgroundIn insects, circadian clocks play a key role in enhancing fitness by regulating life history traits such as developmental time and adult lifespan. These clocks use environmental light/dark (LD) cycles to fine-tune a wide range of behavioral and physiological processes. To study the effect of environmental LD conditions on pre-adult fitness components, we used two dark-dwelling sympatric species of ants (the night active Camponotus compressus and the day active Camponotus paria), which normally develop underground and have fairly long pre-adult developmental time.ResultsOur results suggest that ants develop fastest as pre-adults when maintained under constant light (LL), followed closely by 12:12 hr light/dark (LD), and then constant darkness (DD). While light exposure alters developmental rates of almost all stages of development, the overall pre-adult development in LL is speeded-up (relative to DD) by ~37% (34 days) in C. compressus and by ~35% (31 days) in C. paria. In LD too, development is faster (relative to DD) by ~29% (26 days) in C. compressus and by ~28% (25 days) in C. paria. Pre-adult viability of both species is also higher under LL and LD compared to DD. While pre-adult development time and viability is enhanced in LL and LD, clutch-size undergoes reduction, at least in C. compressus.ConclusionExposure to light enhances pre-adult fitness in two dark-dwelling species of Camponotus by speeding-up development and by enhancing viability. This suggests that social ants use environmental light/dark cycles to modulate key life history traits such as pre-adult development time and viability.

Highlights

In insects, circadian clocks play a key role in enhancing fitness by regulating life history traits such as developmental time and adult lifespan
We collected mated queens of two sympatric species of Camponotus ants (C. compressus and C. paria) while they were landing on the ground near their nuptial flight zones
These ants were introduced into three different light/dark regimes (LL, 12:12 hr light/ dark (LD), and DD) to study the effect of environmental light/dark conditions on preadult fitness components

Summary

Introduction

Circadian clocks play a key role in enhancing fitness by regulating life history traits such as developmental time and adult lifespan. These clocks use environmental light/ dark (LD) cycles to fine-tune a wide range of behavioral and physiological processes. Circadian clocks maximize performance of a wide range of organisms by scheduling rhythmic behaviours at appropriate time of the day These clocks help in anticipating rhythmic changes in the environment [1,2,3], in preparing for events such as migration and reproduction, and in maintaining perfect harmony between behavioural and metabolic cycles [4]. In the fruit fly Drosophila melanogaster [11,13], melon fly Bactrocera cucurbitae [12], and nematode Caenorhabditis elegans [2], circadian clocks have been shown to regulate pre-adult development time

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