Investigating the viability of silkworm eggs after extended low-temperature preservation

Abstract

Silkworm eggs are preserved through successive annual rearing to maintain the genetic resources. However, this process involves risks, such as the loss and mixing of silkworm eggs, highlighting the need for the development of an efficient and safe long-term preservation method for silkworm genetic resources. In this study, silkworm eggs from genetic resources (N29, SA2, and Yang2) and commercial varieties (Baekokjam, Daehwangjam, and Baekhwangjam) stored at low temperatures for two years were hatched using a gradual hatching method aligned with the spring and fall rearing seasons. The hatching rates of silkworm eggs and parameters, such as duration of instar development, survival rates, and cocoon weights, were investigated. The hatching rates of silkworm eggs stored at low temperatures for two years were 87–88% for varieties and 71–75% for genetic resources. Pupation percentages were 79–89% for commercial varieties and 71–79% for genetic resources. When compared to the initial breeding performance, there was a tendency for decrease in hatching rates, pupation percentage, single cocoon weight, and cocoon shell weight after two years of preservation. This study aimed to explore stable preservation methods for silkworm genetic resources and establish a foundation for their industrial application.