Data from: Flexible, but not enough: How an omnivorous ant copes with macronutrient imbalances

Omnivores may have high flexibility in adjusting their ingestion rates and
degree of food selectivity to regulate the nutrient uptake and maintain
homeostasis. However, if resources are limited, their ability to regulate
the nutrient balance may be constrained, affecting their performance and
ecological functions. Here, we studied how an omnivorous ant species,
Dorymyrmex tener, deals with a nutritionally unbalanced diet, which in
turn may affect population dynamics. We first, determined the elemental
composition of D. tener under natural scenarios of resource variability.
Then, to test how different fixed diets (in terms of C:N ratio) influence
pre- and post-ingestive regulating mechanisms, we exposed colonies to two
diets with different C:N ratios (18:1 and 15:1). We measured food
consumption as a proxy of pre-ingestive mechanism, and phenotypic and
behavioral plasticity as a proxy of post-ingestive mechanisms (i.e., body
weight and C:N ratio, and activity level, predator behavior, and
interspecific aggression, respectively). Finally, to determine the colony
performance we assessed worker and juvenile’s mortality. We found that
field colonies of D. tener maintained their homeostasis (measured as C:N
ratio) despite seasonal variations in resource availability. Furthermore,
experimental colonies fed a 15:1 C:N ratio diet showed a higher per capita
food consumption and had marginally heavier workers compared to those fed
the 18:1 diet. However, these dietary differences did not lead to
detectable changes in behavioral traits such as activity levels,
predation, or aggression, nor did they impact overall colony performance.
Our findings suggest that this omnivorous ant possesses a well-developed
regulatory mechanism for maintaining macronutrient balance, primarily
through pre-ingestive strategies. However, its ability to compensate for
nutritional imbalances may be constrained in environments with limited
food diversity, potentially affecting its ecological performance and
resilience.