Development and performance of silkworm, Bombyx mori , as function of mulberry sexual dimorphism

Mulberry (Morus alba) is a dioecious species characterized by sexual dimorphism and constitute the only source of food for silkworm ( Bombyx mori). Sexual dimorphism is characterized by differences in the protein and carbohydrates concentrations, and mineral deposits between male and female trees. The purpose of this study was to explore possible differences in development and performance of two populations of silkworms, one fed with male mulberry leaves (M-fed) and the other one fed with female leaves (F-fed) based on sexual dimorphism characteristics of mulberry. Length and weight measurements of individual caterpillars showed that M-fed larvae developed better than F-fed larvae. Total time of feeding on male leaves was twice as long as for the total time of feeding on female leaves. Electronmicroscopy examinations of the cocoons showed that the external silk fibers produced by M-fed larvae are thicker than those produced by F-fed ones, which correlated to silk dissolution behavior and SDS-PAGE results.