Effect of fenvalerate-20EC on sericigenous insects. I. Food utilization in the late-age larva of the silkworm, Bombyx mori L.

The effect of the common pyrethroid insecticide fenvalerate-20EC (Sumicidine-20EC) on food utilization parameters in the pure multivoltine (Pure Mysore) and pure bivoltine (NB4D2) races of silkworm, Bombyx mori, fed ad libitum with Morus alba, was studied in the final two instars. Insecticide treatment was found to reduce the rates of feeding, assimilation, and conversion along with the efficiencies of conversion of ingested and digested food into body substance. This was due to the toxic effects, which interfered with the silkworms' feeding behavior, and physiology of digestion, and the magnitude of changes increased with the increase in the concentration of fenvalerate used. To overcome the deleterious effects of such pyrethroid insecticides, it has been suggested that the safe periods for use of mulberry leaves contaminated with fenvalerate for summer and winter.