Testing of two microsporidia isolates towards breeds of silkworm resistance

Pebrine disease is a significant disease attacking silkworm (Bombyx mori L.) caused by microsporidia (Nosema bombycis Nageli). This research aims to test breeds of silkworm that are resistant to pebrine disease. Microsporidia are isolated from local seeds (PL-614) and imported seeds (PC-614). The resistance of four breeds of the silkworm is tested by applying the topical method to mulberry leaves sized 3x4 cm2 for the third instar larvae and 5x7 cm2 for the fourth instar larvae. Each spore concentration of microsporid isolates used is 1x105 per ml. The research result shows that breeds of new seeds, namely SS01, SS02, and SS03 are resistant to infection of the two isolates. This research is useful as a reference for the regional or central government to release breeds of new seeds that can replace or complete the existing seeds.