Data supporting: Food limitation and starvation independently affect predator macronutrient selection

Predators are often food limited in their habitat, and some are limited by
specific macronutrients (protein, lipid or carbohydrate). It is
unresolved, however, to what extent and in what way food and macronutrient
limitation are connected. Using a carabid beetle (Nebria brevicollis), we
compared macronutrient self-selection of the animals three times:
immediately after collection in the field, after being fed to satiation
and nutritional balance, and after a subsequent period of starvation. Both
sexes were food and females lipid limited in the field; after 7-21 days of
starvation both sexes increased proportional carbohydrate intake
significantly. Thus, starvation created a nutrient deficit that was
different from what the animals had experienced in the field. We conclude
that while macronutrient limitation in nature may be influenced by hunger
due to food limitation, this is not its main determinant. Nutritional
imbalance of available food may override this effect.