Seasonality Directs Contrasting Food Collection Behavior and Nutrient Regulation Strategies in Ants

Abstract

Long-lived animals, including social insects, often display seasonal shifts in foraging behavior. Foraging is ultimately a nutrient consumption exercise, but the effect of seasonality per se on changes in foraging behavior, particularly as it relates to nutrient regulation, is poorly understood. Here, we show that field-collected fire ant colonies, returned to the laboratory and maintained under identical photoperiod, temperature, and humidity regimes, and presented with experimental foods that had different protein (p) to carbohydrate (c) ratios, practice summer- and fall-specific foraging behaviors with respect to protein-carbohydrate regulation. Summer colonies increased the amount of food collected as the p:c ratio of their food became increasingly imbalanced, but fall colonies collected similar amounts of food regardless of the p:c ratio of their food. Choice experiments revealed that feeding was non-random, and that both fall and summer ants preferred carbohydrate-biased food. However, ants rarely ate all the food they collected, and their cached or discarded food always contained little carbohydrate relative to protein. From a nutrient regulation strategy, ants consumed most of the carbohydrate they collected, but regulated protein consumption to a similar level, regardless of season. We suggest that varied seasonal food collection behaviors and nutrient regulation strategies may be an adaptation that allows long-lived animals to meet current and future nutrient demands when nutrient-rich foods are abundant (e.g. spring and summer), and to conserve energy and be metabolically more efficient when nutritionally balanced foods are less abundant.

Ant nutritional ecology: linking the nutritional niche plasticity on individual and colony-level to community ecology

“…Do species with a broader fundamental nutritional niche occur over wider geographic ranges or different habitat types? Studies using the geometric approach in the laboratory should in the future include more complex paradigms as nutrient regulation strategies may change with colony size or seasonality [38].…”

Resistance to nutritional stress in ants: when being fat is advantageous

“…Foragers in experimentally manipulated colonies might revert to inner-nest tasks -a behavioural shift sometimes associated with an increase in lipid reserves Nakata, 1995;Amdam et al, 2005;Baker et al, 2012;Kuszewska and Woyciechowski, 2013;Bernadou et al, 2015). Lastly, social insects function as long-lived 'super-organisms' that are often confronted with food shortage or food imbalance due to annual seasonal fluctuations in food availability (Cook et al, 2011). This feature of the natural history of social insects offers the intriguing possibility of disentangling the effect of age, task and fat reserves on resistance to nutritional stresses.…”

Ant community (Hymenoptera: Formicidae) associated with Callisthene fasciculata (Spr.) Mart. (Vochysiaceae) canopies in the Pantanal of Poconé, Mato Grosso, Brazil

“…They also found that predators were more abundant in the rainy months, herbivores were restricted to this same period and omnivores were more abundant during the dry season. Changes in the pattern of ant's composition at different times occur due to variations in eating habitats and in the specie's ability to use distinct resources (Meyer et al, 2010;Cook et al, 2011;Castaño-Meneses, 2014).…”