Content difference of 1-deoxynojirimycin in fifty varieties and its correlation with viability of the edible insect Bombyx mori (Lepidoptera: Bombycidae)

Abstract

Silkworm (Bombyx mori) is a traditional edible insect. Whole silkworm powder contains 1-deoxynojirimycin (DNJ). DNJ is an alpha-glucosidase inhibitor with hypoglycaemic activity. The silkworm cannot synthesise DNJ by itself, most of the DNJ in silkworm is obtained by the consumption of mulberry leaves. In this study, the DNJ content of silkworm in different developmental stages and that of 50 representative resource varieties were measured, its correlation with viability of the variety was analysed. The results showed that silkworms at the peak feeding point of the 3rd instar had the highest DNJ content in seven development stages from the 2nd instar to the pupa stage. There was a large difference in the content of DNJ among varieties. The average DNJ content was 7.528 mg/g and the distribution of DNJ content among varieties conformed to the normal distribution (P>0.05). The varieties could be divided into three clusters according to DNJ content, and the DNJ content in cluster III, which contained 11 varieties was higher than other clusters. There were significant differences among polyvoltine species, Chinese species, and Japanese species, and significant differences between colour-cocoon varieties and white-cocoon ones. DNJ content in silkworm larvae was significantly correlated with larval survival rate and larva-pupa rate. In this study, the cluster III with the highest DNJ content may have the potential to be used as preferred raw material for hyperglycaemia regulation or treatment and candidate parent materials for enriched material. Furthermore, DNJ may have a positive effect on the physical fitness of silkworm.