R. Guncheva*

Department of Animal Husbandry – Non-ruminant Animals and Special Branches, Faculty of Agriculture, Trakiа University, 6000 Stara Zagora, Bulgaria

(Manuscript received 12 November 2024; accepted for publication 28 February 2025)

Abstract. The aim of this paper is to determine the significance of the cocoon fluorescence for silkworms Bombyx mori L. susceptibility to artificial diet. The research was conducted during 2021 – 2022 at the Sericulture Training and Experimental Station of the Faculty of Agriculture at Trakia University – Stara Zagora. Individuals of breed “1A” were the subjects studied, which were formed into two groups according to the fluorescent characteristic of the cocoons – violet and yellow. The results of the present study show that the cocoons fluorescence has a highly significant influence (p≤0.01) on the total development duration of the larval stage. In general, individuals with violet fluorescence of the cocoons outperform those with yellow, as at the end of the larval stage, they have a 16.3% higher survival rate and a 2.5-day (61-hour) shorter larval stage development duration. The obtained data in the study give reason to consider that the cocoons fluorescence could be one of the determining factors for the susceptibility of silkworms to artificial diet and can be used in selection for improving some biological traits that are directly related to the economic efficiency of sericulture.