Histochemical analysis of salivary gland of three insects with different feeding habits.
The histochemical tests have been performed to evaluate the polysaccharide and protein contents of the salivary gland of three insects with different feeding habits. Aspongopus janus (Hemiptera), Laccotrephes maculatus (Hemiptera) and larval Euprotis scintillans (Lepidoptera). While the salivary content of E. scintillans includes both acid (AMPS) and neutral (NMPS) mucopolysaccharides, that of A. janus and L. maculatus has only AMPS. The AMPS of E. scintillans and A. janus contains sulphated groups, while that of L. maculatus has carboxyl groups, weakly and/or non-sulphated groups. The histochemical tests for protein reveal the presence of protein-bound--SS,--SH and--NH2 groups and tyrosine-containing protein in the salivary content of all the insects under study. Besides, arginine- and histidine-containing protein has been detected in the gland of A. janus. The possible physiological significance of these histochemical constituents of the gland has been discussed.