Effect of certain fungicides on the induction of dominant lethals in silkworm, Bombyx mori L

Two carbamate pesticides namely Dithane-M(45) and Benlate which are commonly used in sericulture are employed in the present experiment to test their efficacy in the induction of dominant lethals. Different concentrations of 50 to 1000 ppm concentration of each of these two chemicals were administered to Vth instar larvae (one day old) of polyvoltine Pure Mysore and Bivoltine NB4D2 races through leaf feeding method. It has teen observed that commencing from 400 ppm concentrations of Dithane-M(45) and 600 ppm concentration of Benlate induced significant dominant lethality in both the races of silkworm. Further, statistical analysis revealed that percentage dominant lethality has increased in a dose dependent manner indicating the sensitivity of the larval spermatocyte (Vth instar one day old) to higher doses of the chemical. The effect of these two pesticides in two races of silkworm are discussed.