Study on cellular defense of larvae of Utethesia pulchella (Lepidoptera: Arctiidae) against Beauveria bassiana and Isaria farinosae

Cellular immune of insects is one of the important defense methods against foreign agents such as spore of fungi, bactria, nematodes and egg of parasitoides. Identification of immune system help to better use microbial control methods. Cellular immune of 4th instars of Utethesia pulchella L. was investigated against twe isolation of Beauveria bassiana (Fashand and 566) and one isolated of Isaria farinosae (1872c). Activity of hemocytes, nodulation and phenoloxidase activity was measured too. 105 spore/ml concentration of spores was injected to larvae in 1, 3, 6 and 12 h intervals. Control treatment was larvae in which was injected by distilled water. Total of hemocyte, plasmotocyte and granulocyte number was maximum in 3 and 6 h after injection. Plasmotocytes, granulocytes engulfed foreign particles to form nodul. Nodulation was the highest in 3 and 6 h after injection. Phenoloxidase activity was determined in the presence of L-DOPA as a substrate in intervals after injection of fungal spores. There was a direct correlation between phenoloxidase activity and total of hemocyte. Phenoloxidase activity was the highest in 3 and 6 h after injection. Results showed that larvae of U. pulchella haveimmune reaction against spores of 3 isolationes and could be remove foreign agent by nodulation.