The present study was undertaken along with cellular and humoral interactions between larvae of the white grub, Polyphylla adspersa(Col., Melolonthidae) and entomopathogenic nematodes as well to determine possible role of hemocytes in cellular defence. The hemocytes were identified using the method described by Brayner et al (2004) and counted as total and differential number. Five hemocyte types in the hemolymph of second larvae were prohemocytes (1%), granulocytes (64.9%), plasmatocytes (22.9%) ,oenocytoids (2.7%) and spherulocytes (8.5%). The prohemocytes of the pest are round cells, small in size (21.64 ±1.28 μm) with large nucleus that have been surrounded by a narrow cytoplasmic layer. Granulocytes are rounded to ovoid in shape, with 40.96±1.44 μm in size and have small granules in cytoplasm. Plasmatocytes are pleomorphic cells from round to spindle profile with 42.97±2.56 0m in diameter. Those cells have large granules in cytoplasm with irregular appendages in plasma membrane. Oenocytoids are rounded, with 34.05±1.21 0m in size and are distinguished by eccentric nucleus from other cells. Two forms of spherulocytes are observed in the hemolymph of this insect. The dominant morph(72.25±4.130m) has more granule in its cytoplasm as well it is larger than the rare morph(31.2±2.070m). Total density of hemocytes in the second and third larvae was estimated as 2160 and 2696 cells/mm3 hemolymph, respectively. Subsequently, physiopathological studies were carried out based on interaction among the white grub and native species of entomopathogenic nematodes. Results showed that injection of 30 infective juveniles (IJs) of Steinernema glaseri and 50 IJs from Heterorhabditis bacteriophora into the hemocoel of host increased blood volume and changed the hemocyte profiles within minutes after nematodes penetration. Morever, prohemocytes numbers decreased while oenocytoids and plasmatocyte increased before initiating cellular defence reactions. Knowledge about hemolymph cellular interaction with pathogen is a trend in insect pathology that its data is required for selection the best biocontrol agent.

کلمات کلیدی