Seasonal changes in hemolymph amino acids, proteins, and inorganic ions of a desert millipede Orthoporus ornatus (Girard) (Diplopoda: Spirostreptidae)

Abstract

Composition of hemolymph of Orthoporus ornatus (Girard) was examined seasonally. Mean amino acid concentration was highest in early summer at time of molt (June, 61.73 mg%) and lowest in winter (December, 22.53 mg%; January, 32.10 mg%). Protein concentration was lowest in fall (October, 11.63 mg%) and highest in early spring (March, 37.56 mg%). Sodium and Cl− were the main hemolymph ions, accounting for about half of the hemolymph osmolality. Significant seasonal changes occur in concentration of these and other hemolymph ions. Indirect evidence suggests regulation of Na+, K+, Ca2+, and Mg2+. Hemolymph osmolality was higher in winter (December, 295.7 mosmol; January, 321.6 mosmol) than in summer (June, 211.9 mosmol; August, 204.1 mosmol). However, the contribution of measured ions to osmolality was greater in summer than in winter. Fluctuations of some hemolymph parameters suggest association with developmental changes.