3D analysis of the spinning behavior of flossy cocoon mutants in the silkworm, Bombyx mori

To analyze the spinning behavior of flossy cocoon mutants in the silkworm, Bombyx mori, the spinning characteristics of two mutant larvae: W07+, which produced spherical-shaped flossy cocoons, and WO7q constructed peanut-shaped tight cocoons were recorded on videotapes from two different angles and analyzed for spinning behavior by the three dimensional computer graphics software, 3DASBS. WO7+ silkworms constructed an appropriate shape of cocoon very rapidly. On the other hand, WO7q silkworms produced cocoon very slowly and needed more time to form a full cocoon shape than W07+. Both silkworms showed different spinning rates at different spinning stages, although the speed of the WO7q silkworm was comparatively slower in the later spinning stage. The silkworm which constructed a flossy cocoon spun primarily in a C-letter shape changed its direction frequently. On the other hand, the larva of peanut-shaped cocoons often assumed S-letter shapes and displayed a desire to change at a considerably lower frequency. Since the silkworms wO7+ and wO7q are segregated in the strain wO7 which has been maintained for more than 25 years using the same sib mating, different characteristics shown in this experiment should be considered for genetical reasons.