Hereditary of the occurrence of fine fibers separated from the cocoon filament, one of the causes of lousiness, in the silkworm, Bombyx mori

Abstract

 In order to clarify the hereditary of the occurrence of fine fibers separated from the cocoon filaments, which are the main cause of the aggregation of white spots (lousiness) in silk fabric, we generated two silkworm lines using a fine fiber assembly (FFA) method. For genetic analysis, “Asa” (F7) and “Cevennes White” (CV) were used as a line with high FFA value and low FFA value, respectively. We succeeded in generating a line with higher FFA value by inbreeding of F7 while a line with lower FFA value was prepared by inbreeding of CV. The FFA values of F1 crosses between F7 and CV were extremely low, indicating that the gene involved in the oc- currence of the fibers may be recessive. Furthermore, the segregation ratios of BF₁ [(CV × F7) × F7] and F₂ [(CV × F7) × (CV × F7)] showed the presence of minor gene(s) as well as the recessive major gene in the occurrence of the fibers.