Influence of the cocoons fluorescent characteristic on the productivity of silkworms, Bombyx mori L., reared on artificial diet

Establishing the relationship between the productivity of silkworms Bombyx mori L. and the fluorescence of silk sheaths was the aim of the present work. The study was conducted at the educational and experimental base of the Department of Sericulture at the Faculty of Agriculture of Trakia University – Stara Zagora during the period 2021 – 2022. The cocoons used for the purposes of the study were obtained from individuals of breed "1A", reared on an artificial diet (25% mulberry flour). For the purposes of the study, the cocoons were divided into two experimental groups according to the type of fluorescence of the silk sheaths (violet and yellow) when exposed to ultraviolet (UV) rays with a wavelength in the range of 254-365 nm. The results obtained show that fluorescence has an impact (p≤0.05 - 0.001) on some quantitative and qualitative cocoon characteristics. Individuals with violet fluorescence of the cocoons generally demonstrate better technological traits of the products obtained from them – by 9.85% (♀) and 1.13% (♂) better unwindability, by 1.44% (♀) and 1.63% (♂) higher silkiness percentage and by 2.51% (♀) and 0.18% (♂) higher laboratory yield of raw silk compared to cocoons with yellow fluorescence. From the summarized analysis of the data, it can be concluded that the fluorescence of the cocoon is important for the quality of the formed silk sheaths and its determination could be used to improve the productivity of the silkworms.