Cellular immune reactions of Spodoptera litura (Fabricus) (Lepidoptera: Noctuidae) against entomopathogenic fungi Beauveria bassiana

Since microbial factors have important role in control of pests, determination of interactions between immune system and entomopathogenic fungi can be useful in IPM programs. Cellular immunity of 4th instars of Spodoptera litura (Fabricus) was investigated against two isolates of Beauveria bassiana (Fashand and 566) and latex-bead. Number of prohemocytes, granulocytes, oenocytoids and phenoloxidase activity was measured too. A concentration of 106 spore/mL of spores and 106 particle/mL latex-bead were injected to larvae and their interactions with hemocytes were recoreded at 1, 3, 6, 12 and 24 h time-intervals. For control, distilled water was injected to larvae. The number of hemocytes were maximum after 3 and 6 h of injection. Nodulation was occurred 3 and 6 h after injection. Phenoloxidase activity was determined in the presence of L-DOPA as a substrate after injection of fungal spores and latex beads. Phenoloxidase activity was highest in 3 and 6 h post injection. Result showed that hemocytes and phenoloxidase in S. litura had an important role in immune reaction. So, with increasing of hemocyte number, hemocytes aggregated around spores and lead to spore death.