Nutrient Requirements of Pogomyrmex barbatus

Ian Shriner Earlham College
Faculty Sponsor(s): Chris Smith Earlham College
Obtaining and utilizing nutrients efficiently is important for all living organisms. The manner in which organisms best utilize limiting nutrients is particularly complex in super-organisms (such as an ant colony). In this experiment we examined optimal diets and nutrient trade-offs in colonies of the red harvester ant, Pogonomyrmex barbatus. We predicted that the optimal macronutrient ratio (protein:carbohydrate) was likely near the ratio of nitrogen to carbon in adult harvester ant tissue. The results presented are part of an ongoing experiment that began 1.5 years ago, starting with ~150 queen-right colonies. We varied protein and carbohydrate ratios in isocaloric diets (geometric nutritional framework) and measured growth and mortality rates of the colonies. Based on initial data, high carbohydrate levels were inferior for colony growth. A second experiment focused on high protein levels in order to find the optimum for growth. Over the course of the experiment we were also able to see the effect of dietary variation across different environmental contexts through overwintering. Our results suggest that the optimal diet is maintained by the distinct selective pressures of protein sufficiency and protein toxicity. Furthermore, our results suggest the optimal diet varies in response to different environmental conditions.
Biology
Oral Presentation

When & Where

09:30 AM
Gallahue Hall 108