Fungal pathogenicity dependence of the immune system of some lepidopteran larvae I. spodoptera littoralis

ABSTRACT

S. littoralis larvae showed differences in the cellular responses between higher pathogenic fungus Aspergillus flavous and lower pathogenic A. niger fungus compared with non pathogenic, noin biological antigen which is charcoal particles. A. flavous spores caused the death of the larvae after 48 hr of injection while after the injection of A. niger spores and charcoal particles, the larvae stayed alive and complete their life cycle. Total haemocyte counts [THCs] increased from 2 to 12 hr [after injection of A. niger and charcoal and decreased at the following different times post injection [24, 36 and 48 hr or 36, 48 and 60 hr, respectively]. Differential haemocyte counts [DHGs] Showed decreases in plasmatocytes [PL] and Shperulocytes [SP] at the times of high phagocytic reactions to A. niger andA. flavous spores, Granulacytes [GR] numbers increased with the increase in THCs. Coagulocyte [CO] numbers were not significantly changed or sometimes their changes were inconsistent. The larvae failed to phagocytose or nodulate characoal particles and also failed to nodulate both fungal spores. Histological studies on the haemopoietic organs of S. littoralis aimed to demonstrate their roles in phagocytic reaction showed their negative roles