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First published online March 17, 2006
Journal of Experimental Biology 209, 1301-1309 (2006)
Published by The Company of Biologists 2006
doi: 10.1242/jeb.02130

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How well do specialist feeders regulate nutrient intake? Evidence from a gregarious tree-feeding caterpillar

Emma Despland^* and Meghan Noseworthy

Department of Biology, Concordia University, 7141 Sherbrooke West, Montréal, Québec, H4B 1R6, Canada

View larger version (12K): [in a new window]   Fig. 1. Experiment 1. Bivariate means (± s.e.m.) of protein (P) and carbohydrate (C) consumption by insects reared on different diets. (A) Consumption rate per day, (B) total consumption over the entire larval stadium. The lines indicate the expectation under the equal distance rule: a straight line of slope –1. Points on this line indicate that insects on these diets consumed the same total amount of nutrients (and hence total amount of food) during the time period in question.

View larger version (31K): [in a new window]   Fig. 2. Experiment 1. Performance on the different diets (P, protein; C, carbohydrate). (A) Mean stadium duration (days ± s.e.m.), (B) proportion survivorship, onsumption rate (mg dry mass day–1), (D) total food consumption (mg dry mass), (E) growth rate (mg wet mass day–1) and (F) total growth during the stadium (mg wet mass). Values in C-F are means ± one standard error. Different letters indicate differences significant at =0.05 from Tukey post-hoc tests following analysis of variance (for variables on which ANOVA was performed).

View larger version (26K): [in a new window]   Fig. 3. Experiment 2. Bivariate means (± s.e.m.) of protein and carbohydrate consumption by insects on the different treatments. The lines show expected trajectories if the insects had eaten randomly from the two foods presented to them. The amounts eaten are not significantly different from these expected trajectories in all treatments except for treatments 14:28 and 35:7, and 7:35 and 35:7 (protein:carbohydrate).

View larger version (18K): [in a new window]   Fig. 4. Experiment 3. Caterpillar performance during the conditioning period. Estimated marginal means from the analysis of covariance (± s.e.m.) for (A) food consumption (mg dry mass), (B) growth (mg wet mass). PC=21:21, P=21:0, C=0:21, O=0:0; % protein:% carbohydrate.

View larger version (23K): [in a new window]   Fig. 5. Experiment 3. Estimated marginal means from the analysis of covariance for consumption of the two food types during the choice period (mg dry mass, ± s.e.m.). (A) Insects conditioned for 16 h; (B) insects conditioned for 48 h. The x-axis represents the conditioning diet (PC=21:21, P=21:0, C=0:21, O=0:0; % protein:% carbohydrate), and the different shading of the bars represent the two foods (PC=21:0, C=0:21; % protein:% carbohydrate) offered during the choice period.

View larger version (20K): [in a new window]   Fig. 6. Experiment 3. Mean duration of first meal (s; ± s.e.m.) of insects offered either protein only (21:0, P) or carbohydrate only (0:21, C) foods following conditioning on different diets. The x-axis shows the conditioning food (PC=21:21, P=21:0, C=0:21 or O=0:0), and the bars represent the food presented during the observation period.