Effects of water stress and rehydration on hemolymph volume and amino acid content in the blister beetle, Cysteodemus armatus

1. 1. Hemolymph volume, osmolality, amino acid concentrations and fecal amino acid concentrations were measured in a desert blister beetle, Cysteodemus armatus LeConte, which were not desiccated, 10% desiccated (% of body mass), or rehydrated. 2. 2. Desiccation and rehydration had significant effects on the hemolymph volume in this species but not hemolymph osmolality. 3. 3. Total amino acid concentrations were significantly affected by hydration state. 4. 4. Hemolymph urea, asparagine, methionine and histidine were significantly affected by hydration state, but other ninhydrin positive substances (NFS) were not affected. 5. 5. While production of fecal material (frass) decreased with desiccation, the concentration of most amino acids increased, indicating excretion as an avenue of hemolymph osmoregulation.