Article

Communal Nutrition in Ants

School of Biological Sciences and Centre for Mathematical Biology, The University of Sydney, NSW 2006, Australia.
Current biology: CB (Impact Factor: 9.57). 05/2009; 19(9):740-4. DOI: 10.1016/j.cub.2009.03.015
Source: PubMed

ABSTRACT

Studies on nonsocial insects have elucidated the regulatory strategies employed to meet nutritional demands [1-3]. However, how social insects maintain the supply of an appropriate balance of nutrients at both a collective and an individual level remains unknown. Sociality complicates nutritional regulatory strategies [4-6]. First, the food entering a colony is collected by a small number of workers, which need to adjust their harvesting strategy to the demands for nutrients among individuals within the colony [4-7]. Second, because carbohydrates are used by the workers and proteins consumed by the larvae [7-14], nutritional feedbacks emanating from both must exist and be integrated to determine food exploitation by foragers [4-6, 15, 16]. Here, we show that foraging ants can solve nutritional challenges for the colony by making intricate adjustments to their feeding behavior and nutrient processing, acting both as a collective mouth and gut. The amount and balance of nutrients collected and the precision of regulation depend on the presence of larvae in the colony. Ants improved the macronutrient balance of collected foods by extracting carbohydrates and ejecting proteins. Nevertheless, processing excess protein shortened life span--an effect that was greatly ameliorated in the presence of larvae.

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    • "When restricted to a single nutritionally imbalanced diet, food intake is driven essentially by carbohydrate, increasing as the percentage of carbohydrate in the diet decreases (Dussutour & Simpson, 2009). Therefore, when ants are on a highproteinelow-carbohydrate diet, they compensate for the shortage of carbohydrate by drastically increasing their food intake to meet their carbohydrate requirements (Dussutour & Simpson, 2009, 2012). However, this compensation comes at a cost: when ants consume a higher proportion of protein than required, mortality is higher, as observed in many other insects (Hamilton, Cooper, & Schal, 1990; Lee et al., 2008; Maklakov et al., 2008; Pirk, Boodhoo, Human, & Nicolson, 2010). "
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    • "The latter is particularly important when parents and offspring have disparate nutritional needs (e.g., Fewell and Winston 1992), forcing parents to apportion their foraging effort between resources for themselves versus their offspring. Behavioral mechanisms for coping with variation in need include separate foraging trips for self-versus offspring-optimal resources (e.g., Welcker et al. 2009), or foraging proportionately more for offspring as their demand increases (e.g., Eckert et al. 1994; Dussutour and Simpson 2009). Faced both with the need to collect multiple resources and to feed offspring, 2 major questions arise: 1) what resource(s) (and how much of each resource) should organisms collect during a foraging bout? "
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    • "Many animals also live in groups or populations that simultaneously contain individuals of differing developmental stages, and there is abundant evidence that nutritional requirements change throughout an individual's life cycle (Raubenheimer et al. 2007; Simpson and Raubenheimer 2012). Social insects such as ants, for example, live in colonies with overlapping generations, where optimal diets range from the protein-rich diet needed by growing larvae to the carbohydrate-rich diet eaten by nonreproductive adults for colony maintenance (Dussutour and Simpson 2009). Finally , even where individuals appear the same sex and age, heterogeneity in many other traits that may correlate with nutritional requirements is readily observable; examples include between-individual variation in metabolic rate, body size, and life-history strategy (Cam et al. 2002; Honěk 1993; Huchard et al. 2014; Lim et al. 2014; Mathot and Dingemanse 2015). "
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