The Energetics of Interactions in Populations of Tribolium confusum and Tribolium castaneum

Abstract

Caloric determinations were used to define and quantify interactions between populations of Tribolium confusum Duval and Tribolium castaneum Herbst reared at 25°, 30°, and 35°C. Caloric values of food consumed, respiration expenditures, and caloric values for life stages in single and mixed species populations were determined at 10, 20, 30, 40, and 50 days. Single species population data indicated that T. castaneum consumed more food, had consistently higher caloric values in living components and was metabolically more active at all temperatures. Mixed species data indicated that interactions modify the outcome observed for single species populations. Competition was demonstrated only in populations reared at 35°C. Both species had lower caloric values when reared together with T. confusum more negatively effected by the interaction. Predation was the predominant interaction at 30°C. T. castaneum had higher caloric values whereas T. confusum had lower caloric values when compared to their respective single species population caloric values. At 25°C, predation again predominated but T. confusum had higher caloric values whereas T. castaneum had decreased caloric values when compared to their respective single species populations.