Comparative susceptibilities to a nuclear-polyhedrosis virus in the silkworm, Bombyx mori, reared on mulberry leaves and artificial diets

Abstract

Variations in susceptibilities of the various silkworm strains to peroral infection with a nuclear-polyhedrosis virus (NPV) were relatively large when the larvae were fed on artificial piets instead of mulberry leaves. The larvae reared on artificial diets were more susceptible to peroral infection with NPV than those reared on mulberry leaves, and the difference in susceptibility between them increased with larval age. However, no difference in susceptibility to intrahemocoelic infection with NPV was observed of the both larvae, suggesting food quality is important in the susceptibility of larvae to peroral infection with NPV. The gut juice from the larvae fed on mulberry leaves was significantly higher in the antiviral activity than that from the larvae fed on artificial diets. The antiviral activity of the gut juice seemed to be depended on a protease.