Metabolic rates of two hemipteran members of a predator-prey complex

Abstract

1. 1. Metabolic rates (O 2 consumption) and respiratory quotients (R.Q.) were measured in a predator, Geocoris punctipes Say (Hemiptera: Lygaeidae) and its prey, Lygus hesperus Knight (Hemiptera: Miridae) under different temperature and diet conditions. Effects of sex and age of subjects were also measured. 2. 2. Adult females and all nymphal G. punctipes, regardless of diet, had R.Q. that indicated carbohydrates as a major fuel. Adult male R.Q. indicated fats as a major fuel. 3. 3. Except for third instar nymphs which used fat as fuel, the primary fuel for all ages of L. hesperus was carbohydrate. 4. 4. Q 10 (25–35°C) for G. punctipes had a steeper slope (3.7 max) than did L. hesperus (2.2 max), but G. punctipes had lower rates of O 2 consumption, than did L. hesperus. 5. 5. Diet quality had a strong influence on metabolic rate in G. punctipes, with the rates of individuals fed insect eggs being 2–5 × greater than those fed lepidopteran larvae and green beans. 6. 6. Relative adaptive qualities of the different Q 10, R.Q. and metabolic rates for both species are discussed.