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

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.