Özet:

The Hatay yellow strain of silkworm, Bombyx mori L., 1758 (Lepidoptera: Bombycidae) which produces cocoons with an extraordinary yellow color range, is one of the most important endemic and endangered cultural assets in Türkiye. In this study, intense fungal infection and many deaths were detected in the breeding trays in the Hatay yellow breed production facility. An entomopathogenic fungus was isolated from Hatay yellow strain cadavers collected in 2020. According to the morphological and molecular analysis results of the isolate, which was brought into pure culture, it was identified as Beauveria bassiana (Bals.-Criv.) Vuill. (Ascomycota: Hypocreales), the isolate HS1. Phylogenetic analysis results showed that the HS1 strain was very similar (99 %) to the isolates of B. bassiana KJ6 (Iran) and ARSEF 300 (Europe). The concentration-response test using 1 × 104-8 conidia/ml concentrations produced LC50 values of the new strain of 1.2 × 103 and 0.6 × 106 conidia/ml within 7 days against the larvae of Hatay yellow strain and hybrid strain of silkworm, respectively. The results indicated that the virulence of the B. bassiana HS1 strain to the Hatay yellow strain was much more severe and that the Hatay yellow strain had to fight it to survive.