Relative humidity and maintenance of p50 silkworms reared on artificial diet

Abstract

We found that artificial diet rearing of the silkworm strain p50 under high humidity was harmful to adult emergence. Specifically, median relative humidity (RH) greater than 74% during the 5th instar induced a high rate of occurrence of naked pupae, which then died without emerging as adults (Experiment 1). To determine the specific stage in which mortality induced, we divided the last instar period into three stages—early, middle, and late—and then subjected the larvae to low (L: 47% median RH) or high (H: 80% median RH) humid conditions. The occurrence of naked pupae decreased not according to the specific stage of the larvae but to the duration of exposure to the “L” condition (Experiment 2). We propose that to maintain p50 strains on an artificial diet, they should be reared in lower humidity more than 2/3 period in the last instar stage.