Cellular Defense Response to Beauveria Bassiana in the Silkworm, Bombyx mori

Abstract

Cellular defense response of the silkworm, Bombyx mori, to the white muscardine fungus, Beauveria bassiana, was studied using phase-contrast microscopy, hemogram and histological sectioning. Adherence of viable conidia of B. bassiana to granular cells occurred within 10 min and the conidia were initially phagocytized by granular cells 5 hr postinjection, and the phagocytic rate reached the maximum after 12 hr. Plasmatocytes accompanied by granular cells might encapsulate conidia to form the melanized nodules 6 hr postinjection. The phagocytized or encapsulated conidia could germinate from phagocytized or nodules 24 hr postinjection. The total hemocyte count of the silkworm declined as a result of phago cytosis or nodule formation after injection of B. bassiana conidia. The present study indicates that the silkworm may exert temporarily a cellular response to the highly pathogenic fungal spores when injected with a high spore concentration. © 1985, JAPANESE SOCIETY OF APPLIED ENTOMOLOGY AND ZOOLOGY. All rights reserved.