University of Guilan Plant Pest Research 2538-6123 13 2 2023 08 23 Morphology of hemocytes in Plusia gamma (Lep.: Noctuidae) larvae Morphology of hemocytes in Plusia gamma (Lep.: Noctuidae) larvae 81 85 7023 10.22124/iprj.2023.25067.1528 FA M. Ajamhasssani Department of Plant Protection, Faculty of Agriculture, Shahrood University of Technology Journal Article 2023 07 23 Hemocytes are the most important hemolymph components in the circulatory system of insects, which in addition to feeding all cells and tissues of the body, play a key role in physiological defense. In this research, the identification of hemocytes in the gamma moth as a cosmopolitan and omnivorous pest was considered. To perform experiments, hemolymph was collected from pest larvae, and the cells were identified after settling on a slide and staining with Giemsa solution. Five types of hemocytes were observed in the hemolymph of insect larvae, including prohemocytes, granulocytes, plasmotocytes, oenocytoids, and spherulocytes. Prohemocytes are the smallest cells and round with a central nucleus were present in the fourth instar larvae of the moth. granulocytes are larger than prohemocytes, round with abundant granules in the cytoplasm, spindle-shaped plasmotocytes with one or two cytoplasmic cells, egg-shaped onocytoids with a lateral nucleus, and relatively large spherulocytes with spherule-shape cytoplasm. The frequency of granulocytes and plasma cells in fourth and fifth instar larvae was about 70% and more than other cells. While in younger larvae, the density of prohemocytes and plasmotocytes was relatively higher than other cells. Our findings can be used as the first stage of hematology studies of <em>Plusia gamma</em>. Hemocytes are the most important hemolymph components in the circulatory system of insects, which in addition to feeding all cells and tissues of the body, play a key role in physiological defense. In this research, the identification of hemocytes in the gamma moth as a cosmopolitan and omnivorous pest was considered. To perform experiments, hemolymph was collected from pest larvae, and the cells were identified after settling on a slide and staining with Giemsa solution. Five types of hemocytes were observed in the hemolymph of insect larvae, including prohemocytes, granulocytes, plasmotocytes, oenocytoids, and spherulocytes. Prohemocytes are the smallest cells and round with a central nucleus were present in the fourth instar larvae of the moth. granulocytes are larger than prohemocytes, round with abundant granules in the cytoplasm, spindle-shaped plasmotocytes with one or two cytoplasmic cells, egg-shaped onocytoids with a lateral nucleus, and relatively large spherulocytes with spherule-shape cytoplasm. The frequency of granulocytes and plasma cells in fourth and fifth instar larvae was about 70% and more than other cells. While in younger larvae, the density of prohemocytes and plasmotocytes was relatively higher than other cells. Our findings can be used as the first stage of hematology studies of <em>Plusia gamma</em>. https://iprj.guilan.ac.ir/article_7023_623ac54cc932d72784203bd847906545.pdf