Carbohydrates complement high‐protein diets to maximize the growth of an actively hunting predator

Abstract

In nature, food is often variable in composition and availability. As a consequence, predators may need to seek non‐prey food sources. Some predators are known to feed on nectar when food is limited. Nectar and other carbohydrate resources could also be beneficial when prey are more abundant if it helps predators balance protein‐biased diets. We tested if an actively hunting predator, the jumping spider, Phidippus audax , benefited from liquid carbohydrates when prey were not limited. We also tested if the benefit of carbohydrates varied with the nutrient content of prey (i.e., from protein to lipid biased). Spiders were reared on one of six live prey, Drosophila melanogaster , treatments that ranged from high protein to high lipid. Half of the spiders were given access to a 20% sucrose solution. After 2 months, we measured spider mass, cephalothorax width, instar duration, percent body fat, survival, and estimated number of prey eaten. Spiders reared on high‐protein diets with carbohydrates were larger and heavier than spiders on other treatments. Access to carbohydrates also increased percent body fat and survival across prey treatments. Our results suggest that carbohydrates may be a valuable component of spider diets, especially when prey have high protein and low lipid content as is commonly observed in prey in the field. Our results highlight the importance of diet balancing for predators, and that liquid carbohydrates can be an important nutrient to supplement a diet of prey rather than just being an energy supplement during periods of starvation.

The Metabolic Syndrome, a Human Disease

“…In rats, an increased intake of carbohydrates, coupled with lower protein, decreases lipolysis and enhances fat deposition [571,572]. However, an adequate provision of carbohydrates may stimulate growth and predator efficiency [573]. It seems evident that the energy provided by carbohydrates may be best used with the adequate presence of protein in the diet.…”

Networking nutrients: How nutrition determines the structure of ecological networks

“…Animal bodies are typically proteinrich and carbohydrate-poor (Cuff et al, 2021). Whilst some consumers tolerate carbohydrate-rich diets (Hawley et al, 2016;Wiggins & Wilder, 2022;Wilder et al, 2011), non-structural carbohydraterich diets can be detrimental or toxic to other species (Alcántar-Fernández et al, 2019;Hewson-Hughes et al, 2011;Schlotterer et al, 2009). This suggests that nutritional surplus, not just limitation, could structure networks.…”

“…The most limited nutrient is not, however, necessarily the most sought-after by the consumers. Despite some consumers tolerating carbohydrate-rich diets (Hawley et al, 2016;Wiggins & Wilder, 2022;Wilder et al, 2011), non-structural carbohydrate-rich diets can be detrimental or toxic (Alcántar-Fernández et al, 2019;Hewson-Hughes et al, 2011;Schlotterer et al, 2009). Lipids are, however, known to be important and more limited in higher trophic levels of arthropod networks (Wilder et al, 2013).…”