changes in haemocyte count in haemolymph of different larval stages of eri silkworm on application of dimethoate, an organophosphorous pesticide

Research Article
*Navanita Bhagawati and Rita Mahanta
DHC, plasmatocytes, granulocytes, adipohaemocytes, prohaemocytes, sperulocytes, dimethoate pesticide.

In the haemolymph of 4th and 5th instar larvae of the Eri Silkworm (Philosamia ricini) five types of haemocytes have been identified. Changes in the Differential Haemocyte Counts (DHCs) have been assessed in relation to application of graded concentrations of Dimethoate 30EC solution. The haemocyte count was done on 1st , 2nd and 3rd days of post-treatment of sub lethal doses of dimethoate (i.e. 0.5% and 1%) on 4th and 5th instar larvae. Different types of haemocytes registered a dose-dependent response by either exhibiting increase or decrease in

their relative proportions. The adipohaemocytes and prohaemocytes were the most sensitive cells to the pesticidal stress. The plasmatocytes showed least damage on low concentration (0.5%) of dimethoate. Furthermore, the treated insects apparently responded by releasing more granulocytes, into the circulation as evident by increase in the percentage of these cells in treated blood smears compared to the normal.