Abstract

The cellular immune responses of different Indian cross breeds of mulberry silkworm, Bombyx mori L. were analysed by estimating differential haemocyte counts. The test silkworm larvae were immunized with Kanamycin resistant Escherichia coli (E. coli KR) (10-6 cfu/larva). Different types of haemocytes viz., prohaemocytes, granulocytes, plasmatocytes and spherulocytes were enumerated at specified time intervals of 0h, 6h, 12h, 24h, 30h, 36h and 48h in immunized and control larvae to measure the spatial dynamics of DHC (Differential Haemocyte Count). The DHC profiles of cross breed races viz., APM1 x APS8, APM2 x MVT, APM2 x APS12 and APM3 x APS12 showed that the composition of plasmatocytes, granulocytes and spherulocytes were in the range of 17-35, 69-73 and 2-8 per cent respectively. Upon immunization, there was rapid increase in granulocyte population recording as much as 122 per cent rise. Rapid rise in granulocytes was more evident in cross breeds like APM2 x APS12 and APM3 x APS12 as early as 6h after immunization. However, perceptible decrease in granulocytes and plasmatocytes was noticed in immunized larvae after 24-48h. The study brought out distinct differences in spatial and temporal dynamics of differential haemocyte counts in Indian multivoltine cross breeds of mulberry silkworm.

Keywords: Mulberry, Silkworm, Bombyx mori L., E. coli KR, Temporal dynamics and Differential haemocytes.