Accelerative effects of hinoki (Chamaecyparis obtusa) sawdust on the efficiency of natural mounting in Bombyx mori

Abstract

Effects of sawdust of hinoki cypress, Chamaecyparis obtusa, on the efficiency of natural mounting methods of the silkworm, Bombyx mori, was investigated. When hinoki sawdust was scattered over the rearing beds, silkworms mounted to the cocooning frames much more rapidly than the control. In the case of the race C146×N137, 85% of treated silkworms mounted to the frames within 3hr after the scattering, whereas only 30% of untreated silkworms mounted. Scattering of hinoki sawdust increased the mounting efficiency in the netting method, too. Hinoki essential oil had a repellent effect against wandering silkworms and old sawdust with little woody scent had no effect, indicating that these acceleratory effects are mainly due not to physical characteristics of sawdust but to volatile substances from hinoki. These results indicated that hinoki sawdust or repellent chemicals contained in hinoki can be efficient mounting accelerators in the natural mounting of the silkworm.