Communal Nutrition in Ants Audrey Dussutour, Stephen J. Simpson  Current Biology  Volume 19, Issue 9, Pages 740-744 (May 2009) DOI: 10.1016/j.cub.2009.03.015 Copyright © 2009 Elsevier Ltd Terms and Conditions

Figure 1 Protein and Carbohydrate Collection Measured during Choice Experiments (A and B) Empty circles and crosses represent the amount of protein (P) and carbohydrate (C) collected for each replicate for colonies without larvae and with larvae present from the outset of the experiment, respectively. Full circles and full squares show the mean values. The “random” outcomes indicate the expected intake trajectories if feeding had occurred indiscriminately between the two foods in a food pairing treatment (dotted black lines). The solid black lines represent the observed intake trajectory. The solid gray lines correspond to the two foods in a food pairing treatment. Note how colonies with larvae converged upon the same point of nutrient collection in all treatments. Colonies without larvae regulated nutrient collection to a lower P:C ratio than did colonies with larvae, reflecting the increased protein needs of those colonies, and were unable to compensate for the most extreme dilution, indicating a role of larvae in colony nutrient regulation. Three-way ANOVAs: choice effect on food collected and P:C ratio, F1,108 = 0.38 (p = 0.534) and F1,108 = 0.09 (p = 0.781); dilution effect on P:C ratio, F2,108 = 0.01 (p = 0.994); larval effect on P:C ratio and food collected, F1,108 = 792.79 (p < 0.001) and F1,108 = 939.12 (p < 0.001); dilution × larvae effect on food collected, F2,108 = 178.79 (p < 0.001). Current Biology 2009 19, 740-744DOI: (10.1016/j.cub.2009.03.015) Copyright © 2009 Elsevier Ltd Terms and Conditions

Figure 2 Cumulative Protein and Carbohydrates Collected by Ants Colonies were provided with one of five diets that differed in their ratio of protein to carbohydrate at 2 day intervals over 50 days (the results were adjusted to ant mortality). Each diet is represented as a dotted line in the protein/carbohydrates plane in (A) and (B). Within each time interval, the nutrient collection points are connected with lines to and from collection arrays, which demonstrate the nutrient balancing strategy. The inserted images in (A) and (B) show examples of the amount of food left after 2 days. The amount of diet collected by ants at 2 day intervals over 50 days is shown in (C) and (D). Four-way ANOVAs: time effect on the amount of food collected, F24,960 = 106.82 (p < 0.001); time × larvae effect, F24,960 = 8.49 (p < 0.001); time × diet effect, F96,960 = 6.66 (p < 0.001); time × larvae × diet effect, F96,960 = 3.14 (p < 0.001); larvae effect, F1,40 = 63.00 (p < 0.001); diet effect, F4,40 = 17.48 (p < 0.001); larvae × diet effect, F4,40 = 0.60 (p = 0.661). Current Biology 2009 19, 740-744DOI: (10.1016/j.cub.2009.03.015) Copyright © 2009 Elsevier Ltd Terms and Conditions

Figure 3 Protein and Carbohydrates Collected and Ingested, i.e., Not Taken out and Placed on a Waste Dump by Ants after 50 Days (A and B) Ants were provided with one of five diets differing in their ratio of protein to carbohydrate over 50 days. Triangles show the amount of C and P rejected from the food collected. Note how colonies with larvae from the outset were more effective than colonies without larvae in manipulating the composition of collected food by retaining the limiting nutrient and rejecting the excess nutrient in collected food (shaded triangles). The intake target collected is the amount of carbohydrates and protein collected during the choice experiment. The intake target ingested is the intake target once the correction for carbohydrate extraction from the foods collected in the choice experiments is made. Results are presented as intake per ant to adjust for mortality. Three-way ANOVA: diet effect on the amount of stock, F4,40 = 78.61 (p < 0.001); larvae effect, F1,40 = 96.20 (p < 0.001). Four-way ANOVAs with repeated measures: manipulation effect on C and P quantity in the stock, F1,40 = 4068.94 (p < 0.001) and F1,40 = 755.13 (p < 0.001); manipulation × larvae effect × diet effect on C quantity, F1,40 = 8.45 (p < 0.001). Current Biology 2009 19, 740-744DOI: (10.1016/j.cub.2009.03.015) Copyright © 2009 Elsevier Ltd Terms and Conditions

Figure 4 Colony Performance Ants were provided with one of five diets differing in their ratio of protein to carbohydrate over 50 days. (A and B) Mortality for colonies with and without larvae from the beginning of the experiment. (C) Number of larvae produced after 50 days. (D) Number of larvae that hatched after 50 days in colonies in which 60 larvae were introduced at the beginning of the experiment. Three-way ANOVAs: diet effect on the number of dead ants, F4,40 = 25.99 (p < 0.001); larvae × diet effect, F4,40 = 1.28 (p = 0.292); larvae effect, F1,40 = 7.56 (p = 0.009); diet effect on the number of larvae, F4,40 = 47.42 (p < 0.001); larvae × diet effect, F4,40 = 2.29 (p = 0.076); larvae effect, F1,40 = 11.56 (p = 0.002). One-way ANOVA: diet effect on number of ants that hatched, F4,29 = 82.81 (p < 0.001). Current Biology 2009 19, 740-744DOI: (10.1016/j.cub.2009.03.015) Copyright © 2009 Elsevier Ltd Terms and Conditions