Diet-Driven Variations in Longevity and Fecundity of the Endangered Tiger Beetle Cicindela anchoralis (Coleoptera: Carabidae)

TL;DR

The endangered tiger beetle Cicindela anchoralis prefers a high-protein diet, which boosts reproduction but shortens lifespan, highlighting diet-driven trade-offs in survival and reproduction.

Contribution

The study reveals how diet influences life-history trade-offs in an endangered tiger beetle species, with implications for conservation strategies.

Findings

Beetles fed crickets (high-P:C) produced more eggs but lived shorter lives.

Beetles fed ants (low-P:C) lived longer but reproduced less.

Both sexes preferred the high-P:C diet despite the longevity cost.

Abstract

We studied how prey type affects reproduction and lifespan in the endangered tiger beetle Cicindela anchoralis. Tiger beetles fed on crickets (high-P:C) produced more eggs but lived shorter, while those fed on ants (low-P:C) lived longer but reproduced less. Despite this trade-off, beetles of both sexes preferred crickets. This indicates a life-history strategy prioritizing reproduction over longevity. Our findings highlight the ecological significance of diet-driven trade-offs and provide practical guidance for conservation programs. By tailoring diets, breeding efforts can enhance reproductive success, supporting population recovery of this critically endangered insect.

Diet is a key factor modulating the trade-off between fecundity and longevity, a cornerstone of life-history theory. While laboratory studies have demonstrated that high-protein-to-carbohydrate (P:C) ratio diets increase reproductive output at the cost of lifespan, it remains unclear how this trade-off operates in species exposed to natural dietary variability and prey choice. We tested whether diet-mediated trade-offs between fecundity and longevity are modulated by prey-insect type in the endangered tiger beetle, Cicindela anchoralis, a species with a short adult lifespan. Tiger beetles were offered a choice between a high-P:C diet (cricket) and low-P:C diet (ant). Tiger beetles consuming the high-P:C diet exhibited increased fecundity and reduced longevity, while those feeding on the low-P:C diet showed the opposite pattern. Despite these consequences, both sexes showed a consistent preference for the high-P:C diet, suggesting that beetles prioritize reproductive output over lifespan. These results suggest that prey-insect selection might be an adaptive way to boost reproductive success within a limited adult lifespan, which may raise tiger beetles’ intrinsic rate of natural increase. Our findings highlight the ecological relevance of diet-driven life-history trade-offs and offer practical guidance for mass propagation strategies to support endangered tiger beetle recovery.

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