Harvesting Silk Fibers from Role of Environmental Rearing Conditions in Fiber Production and Properties.

Silk fibers are produced by a wide variety of insects. The silkworm () was domesticated because the physical properties of its silk fibers were amenable to the production of fine textiles. Subsequently, engineers have regenerated silk fibroin to form biomaterials. The monocular focus on silk has underutilized the expanse of diverse silk proteins produced by more than 100,000 other arthropods. This vast array of silk fibers could be utilized for biomedical engineering challenges if sufficient rearing and purification processes are developed. Herein, we show that the moth, , represents an alternative silk source that is easily reared in highly regulated culture environments allowing for greater consistency in the silk produced. We controlled the temperature, resource availability (larvae/gram diet), and population density (larvae/mL) with the goal of increasing silk fiber production and improving homogeneity in silk proteins. We determined that higher temperatures accelerated insect growth and reduced life cycle length. Furthermore, we established initial protocols for the production of silk with optimal silk production occurring at 24 °C, with a resource availability of 10 larvae/gram and a population density of 0.72 larvae/mL. Population density was shown to be the most prominent driving force of silk mat formation among the three parameters assessed. Future work will need to link gene expression, protein production and purification, and resulting mechanical properties as a function of environmental cues to further transition silk into regenerated silk fibroin biomaterials.