Abstract: For evaluating the effects of parasitization by Tetrastichus brontispae on immunoreaction of Brontispa longissima, the changes of total number of hemocytes, the percentage of spread plasmatocytes, the rate of melanization, phenoloxidase activity and hemagglutin activity in the parasitized Brontispa longissima pupae were measured. The results indicated that compared with the unparasitized pupae, the parasitization by the parasitoid resulted in a significant decrease in the total number of hemocytes and the spread percentage of plasmatocytes at 2 d post parasitization and a significant increase in the parasitized pupae at 4 d post parasitization. The rate of melanization in the hemolymph in the parasitized pupae was higher than that of the unparasitized pupae during 0.5-2 d post parasitization and decreased to 0 in 3-4 d post parasitization. The phenoloxidase activity in the hemolymph in the parasitized pupae increased significantly at 0.5, 1 and 4 d post parasitization. A peak of the hemagglutin activity appeared at 2 d post parasitization in the parasitized pupae, which decreased to the lowest level at 1 and 4 d post parasitization. The results suggest that the parasitization by Tetrastichus brontispae may result in irregular changes of immunoreaction of its host Brontispa longissima.

Key words: Tetrastichus brontispae, Brontispa longissima, parasitization, immunoreaction, hemocyte, phenolo xidase activity