Influence of Silkworm Breeds and Their Hybrids to BmNPV on Fifth Instar Larval Duration (Days), Pupal Duration (Days) and Silk Productivity (cg/day)

摘要

Nuclear polyhedrosis is the most-common viral disease of the silkworm Bombyx mori. Tolerance to nuclear polyhedrosis virus (NPV) was evaluated in 10 breeds of silkworms. After IIIrd moult the worms were orally inoculated with B. mori NPV two dilutions (10-1 & 10-3) for fourth and fifth instar worms and reared up to the spinning. The biological and economic characteristics were measured in different groups. The results obtained, on fifth instar larval duration is found to be maximum in pure breed CSR16 10.67 and 10.33 days in both the instar when inoculated with two viral dilutions and same has been seen in the control lots 9.67 & 9.67 days. The pupal duration is decreased from 11.33 to 11.67 days & 14.67 to 15.00 days and 11.67 to 12.00 days & 14.33 to 15.33 days in PM and CSR2 at both the dilutions of same instars. However among hybrids, CSR2xCSR4 recorded significantly longer pupal duration of 16.67 (10-3) days in fourth instar instars and 16.67 & 15.67 days in fifth instar respectively. The same trend was noticed in control lots 16.33 and 16.33 days. The silk productivity of experimented breeds was CSR2 and CSR4xCSR16 found highest value of 2.53 & 3.03cg/day and 2.50 & 2.50cg/day (10-1 & 10-3) and 2.83 & 3.14 and 2.12 & 2.20cg/day for both the instars inoculated. Whereas, CSR2xCSR4 (10-1) in fourth instar and CSR2xCSR16 in both the instars at (10-1 & 10-3) both the dilutions did not recorded any of the parameters due to their high sensitivity to BmNPV.