Detailed Explanation of Key Points for New Efficient Rearing Techniques for Late-Stage Silkworms

During the late-stage rearing period, especially the fifth instar, mulberry consumption accounts for about 85% of the entire rearing period, and a large amount of labor, such as removing excrement, feeding mulberry leaves, and picking ripe silkworms, is concentrated in the fifth instar. According to surveys, traditional silkworm tray @#@250@#@. Not only requires a large amount of labor, but also makes silkworm rearers extremely exhausted, with low labor efficiency. Using fixed rearing stands for late-stage silkworms with automatic mounting, without removing excrement, without picking ripe silkworms, and without moving trays up and down, mulberry feeding and mounting are convenient. Compared with traditional silkworm tray rearing, it can save more than 50% of labor and reduce labor intensity by 40%-50%.

I. Making Labor-Saving Rearing Stands for Late-Stage Silkworms

Use wood to make silkworm frames. The width and length of the silkworm frame should be determined according to the width and length of the silkworm room, combined with the width and length of the mounting tools (plastic folding mounts 1.1 m x 0.8 m, cardboard grid mounts 0.4 m x 0.55 m). Generally, there are three specifications of inner width: 1.3 m, 1.8 m, and 2.4 m; the inner clear height between layers is 40-50 cm, and the bottom layer is 30 cm above the ground. If rearing upstairs, the bottom layer should be 50 cm above the ground, which can make full use of the ground layer and increase rearing capacity. Place a wooden frame every 1.5 m. Inside the wooden frame, tie and press one long bamboo pole on each side, then tie 2-4 more bamboo poles in the middle, then place bamboo mats on top of the bamboo poles (placed horizontally on the bamboo poles). Along the four sides of the bamboo mat, tie and press one bamboo pole on each side and lay breathable plastic woven cloth, etc. (never use plastic film as bedding). In this way, a rearing stand (bed) is formed. Generally, rearing one sheet of silkworms requires a rearing stand area of 32-35 sq m. The rearing stand should be more than 10 cm away from the wall to avoid ripe silkworms climbing upward. The silkworm room where the rearing stand is built indoors requires convection windows to ensure good indoor ventilation and fresh air. If one rearing stand is built in the center of the room, leave operation aisles of 60-80 cm or about 1-1.1 m around it; or if one rearing stand is built on each side of the room, leave the aisle in the middle, to facilitate disinfection, mulberry feeding, mounting, cocoon harvesting, and other operations. In summer and autumn, shed-frame rearing stands can be built in shady places such as bamboo groves or woods, which can reduce the harm to silkworms from adverse climates such as high temperature and stuffiness or high temperature and dryness, and achieve stable and high cocoon yields.

II. Labor-Saving Rearing Stand Rearing Techniques for Late-Stage Silkworms

1. Move silkworms onto the stand at the right time. After fifth-instar silkworms have resumed feeding and been given leaves twice, move them together with the leaves to the center of the rearing stand, occupying about 1/3 of the rearing stand area, with the silkworms preferably not touching one another. As the silkworms grow, gradually and naturally expand the rearing bed area toward the surroundings until, at mounting time, the silkworms on the rearing stand just fill it. Place silkworms that resumed feeding in the same batch on the same layer of the rearing stand; place earlier batches on the lower layers and later batches on the upper layers. Never mix early and late batches of silkworms on the same layer of the rearing stand.

2. Good mulberry leaves and satiation feeding. It is required to feed mulberry 4-5 times per day, and to manage the timing and amount of each feeding well. After each feeding, ensure that there are remaining leaves on the rearing bed within two hours, so that the silkworms eat their fill without leaving surplus leaves. Increase the feeding amount appropriately at night. Do not feed overly tender leaves, heated leaves, diseased or pest-damaged leaves, etc., so as to achieve good mulberry leaves and satiation feeding.

3. Strictly prevent stuffiness and poor air. Late-stage silkworms have weak resistance to high temperature and high humidity. Because they eat a lot of mulberry and excrete a lot of frass, the rearing bed is often too humid and prone to producing harmful gases, inducing silkworm diseases. Therefore, when there is no strong wind, generally open doors and windows for rearing. If there is hot and stuffy weather, moderately turn on electric fans for ventilation and air exchange, avoiding harm to silkworms from stuffiness and poor air.

4. Strictly disinfect and remove moisture. Before late-stage silkworms are moved onto the stand, drug disinfection of the silkworm room and rearing stand should be done well. After the silkworms are moved onto the stand, do not remove excrement. Every morning and evening, sprinkle fresh lime powder and lime charred chaff (3:7) once each on the rearing stand for disinfection and moisture removal, so as to keep the rearing bed clean and dry. Never turn over the silkworm excrement, to prevent heating and fermentation.

III. Automatic Mounting of Ripe Silkworms

1. Pick out green silkworms in batches and delay resumption feeding. After about 85% of silkworms have entered the fourth molt, sprinkle lime powder to stop mulberry feeding, and pick out green silkworms for separate rearing. When newly molted silkworms resume feeding, give mulberry only after all molting silkworms have completely shed their skins. In this way, the population can be ensured to develop neatly and uniformly.

2. Add molting hormone to the feed at the right time. When 5%-8% ripe silkworms are seen (commonly called signal silkworms), add molting hormone to the feed in the evening to promote uniform maturation of the silkworms, making it convenient for ripe silkworms to mount automatically.

3. Automatic mounting. After adding molting hormone to the feed, by the next morning the silkworms have basically matured. Sprinkle lime powder or rice straw sections on the rearing bed, then place plastic folding mounts or cardboard grid mounts, and the ripe silkworms will automatically climb onto the mounting tools to find suitable cocoon-spinning positions and spin cocoons. Small silkworm nets can also be covered over the mounting tools (never cover them with plastic film, newspapers, or other non-breathable, non-moisture-permeable materials), which can speed up the cocoon-spinning and cocoon-building rate of ripe silkworms. After mounting, the mounting room should be kept away from light and remain dim, so as to help ripe silkworms spin silk and build cocoons with uniform cocoon layer thickness. After the cocoons have basically formed, pick out floating silkworms, hang the mounts in the middle of the rearing stand with iron wire hooks, open doors and windows, and ventilate to remove moisture, achieving white cocoon color, increasing cocoon yield, and increasing silkworm rearing income.