Hemagglutinin activity in the hemolymph of Anticarsia gemmatalis larvae infected with the fungus Nomuraea rileyi.

Hemolymph samples from larvae of 3 lepidopteran species (Anticarsia gemmatalis, Trichoplusia ni and Spodoptera frugiperda) were tested for hemagglutination activity. Samples from A. gemmatalis larvae which had been injected 12-24 hrs previously with hyphal bodies of the entomopathogenic fungus Nomuraea rileyi showed agglutination activity against human 0, rabbit and sheep erythrocytes. Little or no activity was detected in samples from the other 2 larval species. Low titers (approximately 1:2) were observed when rabbit and sheep erythrocytes were tested with hemolymph from non-injected or water-injected A. gemmatalis control larvae. Higher titers (1:256-1:1024) were obtained when human erythrocytes were incubated with control hemolymph, but values were greater in the hyphal body-injected samples (1:2048-1: greater than 32,000). These results indicate a direct correlation between agglutinin production and the presence of fungal cells in the larval hemolymph. Injection with heat-killed or homogenated hyphal bodies did not cause increased activity. Decreases in titer values after these injections and for 1-12 hrs after injection with viable hyphal bodies suggest that the agglutinin(s) may function in immune surveillance. Agglutination of rabbit erythrocytes was inhibited by lactose, galactose and L-fucose. N-acetylneuraminic acid inhibited agglutination of human erythrocytes.