After the fruitfly, the silkworm Bombyx mori is the insect whose genetics, physiology and pathology are best known. Native to northern China, silkworm is bred for silk production. It is also used as a model for understanding the biology of lepidoptera and arthropods. Major progress has been made, particularly on morphogenesis, protein synthesis, cell differentiation and the action of pheromones. The development of molecular biology has brought new insights into the silkworm as a model organism. Genomics and transgenesis will lead to further progress on the biology of lepidoptera, but also, for example, to increase the resistance of silkworms to disease and to obtain silk of better quality.
As with all lepidoptera, the development of Bombyx mori comprises a succession of 5 larval instars in the form of a caterpillar, then metamorphosis leads to the adult stage, the butterfly. In its domestic status, this butterfly doesn’t fly.
The adult stage is the breeding phase. The female emits a pheromone, an olfactory message, which is perceived by the males’ antennae and attracts them to mate. Immediately after mating, the female lays 300 to 700 eggs (or seeds). When the silkworm emerges from the egg, it is about two millimetres long and covered with hair. It undergoes four moults, then, after weaving its cocoon, it transforms into a chrysalis housed inside the cocoon to metamorphose into a butterfly. The complete life cycle of Bombyx mori lasts about 8 weeks: 5 weeks for the caterpillar stage, 2 weeks for the pupa stage, and finally a few days for the adult stage.
Bombyx Trap database:
« Germline transformation of the silkworm Bombyx mori L. using a piggyBac transposon-derived vector », Tamura et al., Nat. Biotechnol. (2000) 18:81-4
« The genetics and genomics of the silkworm, Bombyx mori », Goldsmith et al., Annu. Rev. Entomol. (2005) 50:71–100
« The genome of a lepidopteran model insect, the silkworm Bombyx mori », The International Silkworm Genome Consortium, Insect Biochemistry and Molecular Biology 38 (2008) 1036–1045