Age related occurrence of natural agglutinins in the erisilkworm, Philosamia ricini

Natural agglutinins against human, guinea pig, and rat erythrocytes (RBC) and bacteria Bacillus thuringiensis were readily detected in hemolymph of final instar larvae with resulting titers of 0-9 (log2). Titers were independent of sex and season but varied conspicuously and reproducibly with age. Moreover, response of hemagglutinins to heating varied with age being heat-labile in younger larvae, yet totally resistant to heating for 30 min at 70 degrees C in older ones. Bacterial agglutinins were uniformly resistant at all larval ages. The study thus reveals that the amounts and physico-chemical properties of P. ricini agglutinins change with larval development. Therefore, larval age should be taken into close consideration before reporting on the occurrence and properties of agglutinins in insects.