ABS 2023
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Fungus garden nutritional needs drive foraging decisions of the desert leafcutter ant�Acromyrmex versicolor
Nathan Smith1, Jennifer Fewell2. 1Bucknell University, Lewisburg, PA, United States; 2Arizona State University, Tempe, AZ, United States

The nutritional needs of animals vary across time and context, which causes variation in their foraging decisions. In social groups that forage collectively, these needs expand to include variation in nutritional requirements of distinct individuals. Leafcutter ant colonies add another dimension to this dynamic, as they farm a fungal symbiont. To assess how foraging decisions are organized in this symbiotic mutualism, we measured the impact of changes in fungal volume and brood number on relative and absolute collection of protein and carbohydrates by colonies of the desert leafcutter ant�Acromyrmex versicolor. Total and relative nutrient intake remained constant following an increase or decrease in the proportion of brood to adults, in contrast to the central role brood play in shaping nutrient collection of non-agricultural ants. Decreasing the proportion of fungus to ants, however, increased absolute nutrient collection with no change in relative nutrient collection. This demonstrates that the fungus garden plays a distinct role in driving nutrient collection by leafcutter ants, and that its nutritional needs shape the colony’s social organization in the context of foraging.