What are the new techniques for rearing silkworms in greenhouses? Detailed explanation of key rearing and management points

Silkworms reproduce by eggs; after the larvae grow a bit, they molt, then become mature silkworms. From the mature silkworm stage they begin to spin silk and form cocoons, and inside them they pupate. When the pupa completes development, it sheds the pupal skin and emerges as an adult. After becoming an adult, it breaks out of the cocoon as a moth, then mates and lays eggs. This is the silkworm's growth process. How should silkworms be reared? Let's learn about it together below.

New techniques for rearing silkworms in greenhouses

1. Site selection Choose a location with flat terrain, smooth drainage, far from rice fields, vegetable plots, and orchards, and relatively close to mulberry fields to build the greenhouse.

2. Time to enter the greenhouse Keep the inside of the greenhouse dry. For a newly built greenhouse, uncover the film during the day to sun the greenhouse, and cover the film at night to prevent moisture inside. Before placing the silkworms, first lay 1 layer of film on the ground, then lay 1 layer of rice straw on the film, and place the silkworms on the rice straw. For co-rearing during instars 1-3, they can enter the greenhouse on the 2nd day of the 4th instar or the 2nd day of the 5th instar.

3. Temperature regulation Greenhouses generally have a higher temperature than indoor silkworm rooms, and the temperature difference between day and night is relatively large. The key to temperature regulation in the greenhouse is to strengthen ventilation on the basis of good cooling. High temperatures can be alleviated through the following measures:

1. Cover with shade materials Covering the roof with shade materials helps lower the temperature inside the greenhouse. Commonly used shade materials include shade nets and straw curtains. For roof covering with shade nets, the cooling effect of 2 layers is better than 1 layer. The inner layer should fit closely against the plastic film, and the outer layer should be about 15-20 cm away from the greenhouse roof, and extend out about 1.5-2 m on both sides of the greenhouse to form an outer corridor, which is more helpful in preventing direct sunlight on both sides. According to surveys, this method can reduce the temperature inside the greenhouse by 3-4 degrees C. If the roof is covered with straw curtains, it should not be too thick, so as to reduce the weight on the roof on rainy days. In addition, planting vines around the greenhouse and using green shade can effectively lower the temperature inside the greenhouse.

2. Spray water on the roof During high-temperature periods, starting from 9 a.m., spray water once every 1 hour until around 3 p.m. According to surveys, spraying water on the roof can reduce the temperature inside the greenhouse by 1-2 degrees C.

3. Strengthen ventilation On sunny days after sunrise, uncover the film on both sides of the greenhouse for ventilation and air exchange. In the evening, when the temperature inside the greenhouse drops below the suitable rearing temperature, lower the film on both sides to keep it warm. When the temperature is relatively high, ventilate day and night. On rainy days, lower the shade nets on both sides of the greenhouse and lift the film on both sides of the greenhouse to facilitate air circulation.

4. Feed wet leaves as appropriate High temperatures inside the greenhouse and ventilation can easily cause mulberry leaves to wilt, so wet leaves can be fed at noon on sunny days, and at the same time spray in the air with 0.3% effective chlorine concentration bleaching powder solution to supplement moisture and prevent disease.

4. Branch mulberry rearing Greenhouse rearing emphasizes ventilation, and rearing with whole leaves easily causes mulberry leaves to dry out, so branch mulberry rearing is preferable. After the silkworms enter the greenhouse and are given mulberry leaves for the 2nd time, branch mulberry rearing can be adopted. Feed mulberry leaves 3 times per day. The amount of mulberry leaves fed should be based on the characteristics of high rearing temperature and fast development in the greenhouse, feeding enough mulberry leaves in advance. Generally, when about 10% residual mulberry remains, feed the next round of mulberry. However, the amount and frequency of mulberry feeding should also be reasonably adjusted according to the development of the silkworms and weather changes.

5. Disease and pest prevention Carry out disinfection before silkworm rearing according to conventional methods. For greenhouses used continuously, before using chemicals, about 10 cm of surface soil should first be removed. After disinfection and before silkworm rearing, first spread 1 layer of chlordane powder on the ground, then spread 1 layer of fresh lime powder. During the silkworm rearing period, spread more dry materials. In rainy, stuffy, and hot weather, use fresh lime powder once in the morning and once in the evening to disinfect the silkworm body and silkworm seat. For those entering the greenhouse for rearing at the 4th instar, the silkworm droppings should be removed promptly after the first feeding of the 5th instar, and the silkworm seat should be cleaned.

6. Mounting on clusters at the right time The temperature inside the greenhouse is high, and the silkworms mature quickly, so preparatory work should be done early. One day before seeing maturity, switch to feeding whole leaves, and use short rice straw to level the silkworm seat, while spraying the silkworm body once with silkworm fly control. When about 5% are seen mature, begin placing the silkworm mounts. Before placing the silkworm mounts, spread 1 layer of fresh lime powder for disinfection, then feed 1 round of whole leaves. Be careful to avoid mounting over-mature silkworms, otherwise a large number of mature silkworms will spin cocoons in the silkworm seat and cause losses; also be careful to shade light to avoid excessive light increasing losses from cocoon spinning in the silkworm seat.

Preparation before silkworm rearing

Before rearing silkworms, silkworm farmers should complete the following four aspects of preparation.

1. Report the number of silkworms

New mulberry-growing households can report the number when the mulberry height is about 0.7 m. Old households can report the number for the first batch in spring and autumn when the mulberry height is about 0.5 m, and report the number of the next batch when receiving silkworms for other batches. 1 sheet of silkworms requires 450-500 kg of mulberry leaves, and it takes about 25 days from reporting the number to receiving the silkworms.

2. Silkworm room

The silkworm room requires a flat, clean floor, with convection windows at the front and back, and preferably low windows. Doors and windows should be fitted with screens to prevent flies, and low windows should be fitted with wire mesh to prevent mice. Both greenhouses and cement rooms are acceptable (in cold weather, cement rooms are best; in hot weather, greenhouses are best). Rearing 1 sheet of silkworms requires about 30 sq m of silkworm rearing area and 10 sq m of dedicated mulberry leaf room.

3. Silkworm tools and medicines

For 1 sheet of silkworms, prepare the following silkworm tools and medicines: 1) 15-20 silkworm baskets 0.8 m wide. 2) Four leaf-collecting baskets and about 20 sq m of medicinal film. 3) 2-3 pairs of slippers, placed respectively in the silkworm room and the mulberry leaf room. 4) Several red bricks, mainly to make feeding silkworms convenient during ground rearing; generally place 2 rows of bricks in each room to facilitate walking back and forth. 5) 2 buckets dedicated to disinfection of the silkworm room and 1 sprayer. Buckets and sprayers that have held pesticides must absolutely not be used to disinfect the silkworm room. 6) 260 square-grid baskets. 7) About 60 kg of lime, prepared by sprinkling a small amount of water 3 days before receiving the silkworms.

4. Disinfection

Disinfection is the prerequisite for preventing and controlling the occurrence of silkworm diseases and ensuring high yield and high quality in silkworm rearing, and must be carried out conscientiously. The first disinfection should be completed within 1 week before receiving the silkworms. First thoroughly clean the silkworm room, mulberry leaf room, and surrounding environment. Silkworm tools can be placed in the sun to dry, and then the silkworm room and silkworm tools should be disinfected. At present, the best medicine is Xiaoteling. The preparation method of Xiaoteling is: first crush the main agent, stir it into a paste with a small amount of water, then pour in 25 kg of water, then add the auxiliary agent and stir slightly, and let it clarify for 15 minutes before use. Use a dedicated sprayer to disinfect the silkworm room and all silkworm tools. Disinfection should be comprehensive and thorough. Indoor walls and floors should be sprayed evenly and thoroughly. After spraying, close doors and windows and keep them moist for 1 hour. After the disinfectant dries completely, repeat the disinfection 1 time according to the above method. Soaking film, shoes, silkworm tools, etc. in the medicinal solution for disinfection is more effective. After disinfecting the silkworm room 2 times, open the doors and windows. Note that disinfected silkworm rooms must not be placed with undisinfected items.

How to save mulberry leaves in silkworm rearing

Under normal silkworm rearing conditions, 15 kg of mulberry leaves are needed to produce 1 kg of silkworm cocoons. After adopting mulberry leaf-saving measures, about 50 kg of mulberry leaves can be saved per sheet of silkworm eggs, while the yield and quality of silkworm cocoons are not affected at all. The mulberry leaf-saving measures are:

1. Mulberry leaves should be reasonably picked, transported, and stored. Try to pick leaves in the morning or evening, transport them as they are picked, load them loosely, and transport them quickly. After the picked mulberry leaves are loosened, place them in a mulberry storage pond or mulberry storage room and store them reasonably to prevent wind damage or heat buildup and deterioration from causing waste of mulberry leaves.

2. Prevent mulberry leaves from wilting. During the young silkworm stage, use heated bed (room) rearing and plastic film mulching rearing to help keep warmth and moisture and keep mulberry leaves fresh. During the large silkworm stage, after feeding the silkworms, properly close doors and windows, and after the silkworms have eaten about 70% of the mulberry leaves, open doors and windows for ventilation, which can effectively prevent mulberry leaves from wilting.

3. Ensure the temperature of the silkworm room. The suitable temperatures for large and small silkworms are 24 degrees C and 25 degrees C respectively. Within the suitable temperature range, silkworms have a strong appetite, reducing leftover and poor-quality mulberry leaves, and also increasing the conversion rate of leaves to silk.

4. Promote fewer-feeding rearing and branch mulberry rearing. Labor-saving silkworm rearing techniques such as once-a-day rearing in flat and three-dimensional forms for young silkworms, twice-a-day rearing for all instars, and branch mulberry rearing for large silkworms not only improve silkworm rearing efficiency, but also help silkworms eat mulberry leaves, saving about 5% of mulberry leaves compared with ordinary rearing.

5. Planned mulberry use and quantitative mulberry feeding. Formulate standard mulberry amounts by instar, by day, and by feeding round according to different silkworm stages, so as to achieve "silkworms eat their fill without waste, save mulberry leaves without starving silkworms." At the beginning and end of each instar, the amount of mulberry eaten by silkworms decreases, so feed an appropriate amount of leaves at this time. During the peak feeding period of the 5th instar silkworms, let the silkworms eat their full, but the maximum daily mulberry amount should be controlled within 110 kg.

6. Add molting hormone to the feed. When about 5% of silkworms are seen mature, use 1 vial of molting hormone per sheet of eggs, dilute with 25 kg of water, mix with 20 kg of mulberry leaves, and let the silkworms eat it all at once, which can promote the silkworms to mature all together and can save about 10 kg of mulberry leaves per sheet of eggs.

Living habits of silkworms

Silkworms are metamorphic insects. The most common is the mulberry silkworm, also called the domestic silkworm, one of the economic insects that feed on mulberry leaves and spin silk to form cocoons. The mulberry silkworm originated in China. Its development temperature is 7-40 degrees C, and the suitable rearing temperature is 20-30 degrees C. Silkworm babies live on mulberry leaves. After continuously eating mulberry leaves, their bodies become white, and after a period of time they begin to molt. Molting takes about one day, during which they do not eat or move, like sleeping; this is called "dormancy." After one molt, they are second-instar larvae. Each molt counts as adding one year of age. The larvae molt four times in total, becoming fifth-instar larvae, then eat mulberry leaves for 8 days to become mature silkworms and begin to spin silk and form cocoons.

In the past, silkworms were reared indoors, but now greenhouse rearing has appeared. Greenhouse silkworm rearing has reduced many costs. Especially in hot weather, greenhouse silkworm rearing is more suitable. Greenhouses are relatively more ventilated. Preparation in the early stage of silkworm rearing is also very important. Only by doing a good job in early preparation can later rearing work be benefited.