Morphology of Hemocytes in Spodoptera litura (Lepidoptera: Noctuidae), forest berry pest

The role of hemolymph factors, especially hemocytes, in combating foreign invaders introduced into the hemolymph, is crucial, and identifying these cells and their diversity is the first step in insect immune studies. Therefore, the present study aims to investigate the morphology of hemocytes in the larvae of Spodoptera litura. Fifth instar larvae were used in the experiments. The larvae were reared under the conditions of a temperature of 25 ± 1 °C, relative humidity of 50%, and a photoperiod of 14:10 (light:dark). Based on observations using a light microscope at 40× magnification, five types of hemocytes, including prohemocytes, plasmatocytes, granulocytes, oenocytoids, and esferocytes, were found in the hemolymph of the insect larvae. Prohemocytes were rounded with a large central nucleus, and their abundance in the hemolymph of fifth instar larvae was approximately 10%. Plasmatocytes were commonly observed in a binucleated form with distinct elongated and pointed protrusions, as well as in a worm-like shape. These were the largest hemocytes in terms of longitudinal size. They had a centrally positioned distinct nucleus and granular cytoplasm. The abundance of plasmatocytes was approximately 38%. Granulocytes were round and larger than prohemocytes, characterized by numerous granules in their cytoplasm. They exhibited the highest abundance among hemocytes. Oenocytoids had a circular shape and a lateral nucleus, with an abundance of approximately 8%. Esferocytes had a vacuolated cytoplasm and thin cell walls. They had the lowest abundance among hemocytes in the fifth instar S. litura larvae, accounting for less than 1%.