International Journal of Entomology Research 80 International Journal of Entomology Research ISSN: 2455-4758 Impact Factor: RJIF 5.24 www.entomologyjournals.com Volume 2; Issue 6; November 2017; Page No. 80-83 Haemocyte types and count in Bradinopyga geminata (Rambur) (Anisoptera: Odanata) 1 Raveen R, *2 Nalini M 1 Department of Zoology, Madras Christian College, Chennai, Tamil Nadu, India 2 PG & Research Department of Zoology, Poompuhar College, Melaiyur, Tamil Nadu, India Abstract Seven haemocyte types were identified in the haemolymph of adult Bradinopyga geminata (Rambur) (Anisoptera: Odanata) viz., Prohaemocytes, plasmatocytes, granulocytes, oenocytoids, adipohaemocytes, spherulocytes and vermicytes. Prohaemocytes, plasmatocytes and granulocytes were the most numerous circulating haemocytes in the haemolymph of Bradinopyga geminata. Prohaemocytes were the smallest cell type, spherical in shape with a centrally located large nucleus. The plasmatocytes were polymorphic with or without cytoplasmic extensions. The granulocytes were spherical or oval in shape with characteristic basophilic granules in the cytoplasm. Oenocytoids were the largest of all the cell types with a large nucleus and a homogenous cytoplasm. Adipohaemocytes were polymorphic, varied from small to large cells mostly irregular in shape with prominent lipid- like inclusions. The spherulocytes were characterized by the presence of highly basophilic or acidophilic spherules. Vermicytes were fusiform with a centrally located nucleus. The total and differential haemocyte counts were also done. Keywords: bradinopyga geminata, haemocytes Introduction Insect haemocytes are a mixture of cell types with varying functions. They are morphologically distinct cell types [1, 2] , comparable to vertebrate leucocytes [3] constituting important and crucial components of the haemolymph in the open circulatory system of insects as well as in other arthropods and invertebrates [4] . The role of haemocytes is to defend the insects against pathogens and parasites that enter their haemocoel [5] . Functionally, haemocytes are the generally accepted cellular defense units in insects and are partially responsible for their immune responses [6, 8] . A primary defense response is encapsulation, a process in which haemocytes attach to the foreign organisms, immobilize by surrounding and killing them. They recognize a variety of foreign targets as well as alterations to self. These haemocytes possess the ability to discriminate stranger agents, mediate phagocytosis, cytotoxicity, encapsulation, wound repair and coagulation [4, 9, 10] . Classification of haemocytes is based on morphology or a combination of morphological and functional characters [11, 14] , however, they were first discovered by Swammerdam [15] . Overall five to seven types of haemocytes have been frequently described in insects viz., prohaemocytes, plasmatocytes, granulocytes, spherulocytes, adipohaemocytes, oenocytoids and coagulocytes [4, 5, 16, 17] . The odonate Bradinopyga geminata (Rambur), commonly called Rock dweller, is black in colour with white patches, frequently seen on the dark surfaces, such as rocks, uncemented compound walls etc., to avoid the predators. Usually the female adults lay their eggs in the open water tanks on the top of houses. Moreover, the nymphs are highly voracious feeders of mosquito larva and can be used to control the mosquitoes. This study aims at characterizing the haemocyte types, as well as the total and differential haemocyte counts of these normal adult dragonflies since the success of the immune response depends on the number and types of haemocytes involved in these mechanisms [18] . Materials and methods The adult Bradinopyga geminata perched on walls and water tanks were gently captured using an insect net from the Madras Christian College campus, Tambaram, Chennai, Tamil Nadu, India. Haemolymph collection and preparation of slides The dragonflies were delicately punctured with a needle in the abdominal region and the haemolymph was bled directly on a glass slide and allowed to air dry for 20-30 minutes. During this time, the haemocytes adhered to the glass slide. Cells were then fixed in methanol for five minutes. After air drying of the fixative, haemocytes were stained with Giemsa- Rosenfeld for 3-4 minutes and the slides were rapidly washed with double distilled water. After air drying, the glass slides were dehydrated and mounted in DPX [19] . Haematology Haemolymph was obtained by delicately puncturing the abdomen with a micro needle. Haemocyte counts were performed on individual adults. Total Haemocyte Counts (THCs) were done by loading diluted haemolymph to a Neubauer haemocytometer [20] . The haemolymph (5μL) was mixed thoroughly with 5μL Versene saline (NaCl 0.9g, KCl 0.942g, CaCl2 0.82g, NaHCO3 0.002g and EDTA 2g in