Raymond Patana

Ontogenetic and stress-related changes in hemolymph chemistry of beet armyworms

Abstract 1. 1. Concentrations of various hemolymph components were measured in 3rd instar to adult beet armyworms, Spodoptera exigua Hubner, and also in 4th instar larvae subjected to temperature and water stress. 2. 2. Hemolymph volume remained constant (34.9–41.5%) among the larval instars, but osmotic potential dropped from 431 mOsm/kg in 3rd instars to 353 mOsm/kg in the adult stage. 3. 3. In cold stressed larvae, hemolymph volume rose significantly (to 51.6%) and osmotic potential was elevated (to 398 mOsm). 4. 4. Concentrations of most ions remained constant among the larval instars, but changed significantly (especially K) in the pupal and adult stages. 5. 5. Stress conditions had little effect upon ion composition except for K and Ca. 6. 6. Protein concentrations in pupae and adults increased to more than 1.5 times the larval levels, while amino acid concentrations decreased in pupae and adults. 7. 7. Carbohydrate concentrations were 1 6 as high in pupae as in larvae, and in adults they were 5 times as high as in pupae. 8. 8. Cold stress caused an increase in protein concentrations, while heat stress caused larval amino acid concentrations to increase; and starvation and desiccation caused amino acid concentrations to decrease. 9. 9. Carbohydrate concentrations were lower in all stressed larvae.