author(s)
Jayashree, Manjunath Gowda, KC Narayanaswamy and R Narayana Reddy

abstract
Four thermotolerant bivoltine breeds viz., B1, B4, B6, B8 and their hybrids viz., B1× B4, B1× B6, B1× B8, B4× B1, B4× B6, B4× B8, B6× B1, B6× B4, B6× B8, B8× B1, B8× B4 and B8× B6, were topically inoculated with different dilutions of the fungal spore suspension of Beauveria bassiana viz., [stock (3.17 × 10⁵ spores / ml), 10^-2, 10^-4, 10^-6 and 10^-8]. The results revealed that the thermotolerant bivoltine silkworm breed B8 and hybrid B1× B8 performed significantly better than any breed and hybrid for all the eight parameters studied, viz., cocoon yield by number, cocoon yield by weight, single cocoon weight, pupal weight, shell weight, shell ratio, filament length and filament weight. While, the next better breed and hybrid was B1 and B1× B4 performing better for cocoon weight, pupal weight, shell weight and pupal weight. This study was conducted with an objective to screen whether thremotolerant bivoltine silkworm breeds and their hybrids can also tolerant white muscardine infections exhibiting dual stress tolerance.