Detailed Explanation of Key Techniques for Handling the Molt and Waking Stages of the Silkworm
I still remember that when I was little, the editor also loved raising silkworms very much. The first thing I did every day after coming home from school was open my box to see whether the little silkworms inside had grown a bit. But for the editor, that was purely a child raising them for fun. People who truly raise silkworms need to pay attention to many things!
Techniques for Handling the Molt and Waking Stages of the Silkworm
The level of silkworm rearing technique and the level of cocoon yield are mainly reflected in how well the work of handling the silkworm's molt and waking stages is done. Handling the molt and waking stages includes three processes: pre-molt handling, protection during the molt period, and handling of newly woken silkworms.
1. Pre-molt handling. When the silkworms enter the reduced-feeding period, they should be given a molting bed, feeding 1—2 rounds of leaves, that is, carrying out molting bed cleaning just before they settle into molt, so that the molting silkworms have a dry rearing bed. The amount of mulberry leaves given before molting should be gradually reduced, which neither wastes mulberry leaves nor helps make the rearing bed flat and facilitates netting. After the vast majority of silkworms have settled into molt, for silkworms in instars 1—3 use 3 parts charred chaff and 7 parts fresh lime powder; for silkworms in instars 4—5 use fresh lime powder sprinkled on the rearing bed to stop feeding, then lift the net for the green-head silkworms, move the lifted net into another rearing tray, combine the green-head silkworms and place them on the upper layer of the rearing rack, and feed them high-quality mulberry leaves to promote development, so that after 3—4 days they can catch up with the development pace of the large batch of silkworms. Pay attention to observing the green-head silkworms and promptly cull the weak and diseased ones among them. Green-head silkworms should be reared separately and not mixed with the large batch of silkworms, to prevent the spread of silkworm diseases.
2. Protection during the molt period. The length of the silkworm molt period is relatively obviously affected by temperature. Under normal temperature protection, the molt period of instar 1 is about 22 hours, instar 2 is 18—20 hours, instar 3 is 24 hours, and instar 4 is 44—46 hours. During the molt period, the temperature should be about 1°C lower than usual rearing temperature. In the early stage of the molt (from the start of shedding to before the first feeding after waking), the difference between dry and wet bulb temperatures should be about 2°C; slightly higher humidity helps the silkworms shed their skins. The environment during the molt period should be quiet; the light should be dim; keep the air fresh; and prevent strong winds from blowing directly on them.
3. Handling of newly woken silkworms. After the silkworms shed their skins, when the head is light brown it is the suitable time for the first feeding after waking. Appropriately delaying the first feeding after waking is beneficial for uniform development of the silkworms and has no adverse effect on silkworm constitution or cocoon yield. For spring silkworms and mid-to-late autumn silkworms, feed when 90%—95% have shed their skins; for summer silkworms and early autumn silkworms, when temperatures are higher, feed when 85%—90% have shed their skins. Before the first feeding after waking, use silkworm bed disinfectant or Disease Prevention No. 1 or anti-stiffening agents to disinfect the silkworm bodies and rearing bed, so as to kill pathogens. After the first feeding after waking, feed two rounds of leaves and carry out cleaning of the newly woken silkworms. If the silkworm heads are rather crowded and dense, and they were not divided into batches before molting, and the newly woken silkworms are not uniform, then they can be fed in two batches, that is, after disinfecting the silkworm bodies and rearing bed, add a net and give mulberry leaves, and pay attention to observing when half the silkworms have climbed onto the net, then lift the net. After several hours, once all the late-molting silkworms have shed their skins, carry out the second feeding after waking. There are two methods for dividing batches by adding nets at the first feeding after waking: one is to place two nets horizontally on each rearing tray (each covering half of the rearing bed area); when cleaning the newly woken silkworms, place each net into one rearing tray, that is, divide the silkworms of one tray into two trays. The other method: first place one net vertically on each rearing tray, with the net area slightly larger than the rearing bed. When about half the silkworms have climbed onto the net, lift the net, then add a net again and give mulberry leaves to the other half of the silkworms, and carry out cleaning of the newly woken silkworms. This can save time in expanding the rearing bed, and the silkworm bodies will not be injured. The leaves used for the first feeding after waking should be suitably mature but on the tender side, and the amount of leaves fed should be small to prevent waste. As the amount of mulberry leaves eaten by the silkworms increases, the amount of leaves fed also increases accordingly.
What Is the Silkworm
The silkworm is a silk-secreting insect of the order Lepidoptera that feeds on mulberry leaves. It is an invertebrate, belonging to the phylum Arthropoda, family Bombycidae, genus Bombyx, species Bombyx mori. The main objects of mulberry cultivation and silkworm rearing are silkworm cocoons and silk. In its lifetime, the silkworm goes through 4 developmental stages that are completely different in morphology and physiological function: egg, larva, pupa, and adult. Different parts of each developmental stage and their metabolites have broad medicinal value. The mulberry silkworm, also called the silkworm, or simply the silkworm, is one of the economic insects that feed on mulberry leaves and spin silk to form cocoons. The mulberry silkworm belongs to the order Lepidoptera, family Bombycidae. The mulberry silkworm originated in China, and was domesticated from primitive silkworms that lived on mulberry trees in ancient times. It is homologous with the wild mulberry silkworm that currently damages mulberry trees in China, and both have 28 pairs of chromosomes.
Environmental Factors in Silkworm Rearing Techniques
1. Temperature. Silkworms are poikilothermic animals. Their body temperature changes with changes in the external temperature. The temperature range for normal growth and development of silkworms is 20-30°C. Within the suitable temperature range, the higher the temperature, the faster the growth and development. Above 30°C and below 20°C, the growth and development speed of silkworms is slow, which is not conducive to silkworm growth, and long-term exposure affects silkworm health.
2. Humidity. Humidity in the environment can affect silkworm growth, development, amount of mulberry leaves eaten, digestion and absorption, shedding of skins, and rearing bed hygiene, etc. In a humid environment, silkworms breathe vigorously, eat more mulberry leaves, digest and absorb faster, grow and develop quickly, and have shorter instars. However, high humidity makes pathogenic microorganisms reproduce quickly, and silkworms are prone to infection and disease. A dry environment is beneficial to rearing bed hygiene, but mulberry leaves easily wither and affect feeding, causing starved silkworms, thin and small silkworm bodies, and difficulty in shedding skins. Therefore, air humidity with a dry rearing bed is better. The suitable humidity range: for young silkworms, relative humidity for instar 1 is 90%, then decreases by 5% for each subsequent instar, and for instar 5 large silkworms 70%-75% is suitable.
3. Air and airflow. Silkworms must continuously absorb oxygen from the air for normal life activities, and require fresh air. Silkworms must not come into contact with carbon monoxide, carbon dioxide (concentration exceeding 1%), ammonia, fluoride gases, tobacco, pesticides, paint, camphor, gasoline, and other harmful gases. After contact, silkworms will suffer poisoning, harm, and death. Boleixiu suggests that the silkworm room should have doors and windows opened regularly to remove stale air and bring in fresh air. Young silkworms require weak airflow, and large silkworms require good ventilation and air exchange.
4. Light. Silkworms have the instinct to move toward a light source. Toward strong light, they have the characteristic of moving away from the light source. Newly hatched silkworms have the strongest phototaxis, and as the instar advances, the phototaxis gradually weakens. Among the same instar, newly woken silkworms have the strongest phototaxis. The light in the silkworm room should preferably be natural scattered light, so that the silkworms are evenly distributed on the rearing bed, eat mulberry leaves evenly, and develop uniformly. If there is about 16 hours of light and about 8 hours of darkness in a day, the silkworms will grow normally and develop uniformly.
Precautions for Raising Silkworms
1. Put the silkworm eggs in a box and wait for them to hatch. The most suitable temperature is 25°C-28°C. If the temperature is lower, you can cover it with a lid. Newly hatched young silkworms must be cared for with special care, and fed with relatively tender leaves.
2. Keep mulberry leaves fresh, feed an appropriate amount each time, and keep the rest in the refrigerator to preserve freshness. Mulberry leaves must be clean, otherwise the silkworms will get sick after eating them; if the mulberry leaves turn black and moldy, do not feed them to the silkworms. When feeding mulberry leaves to silkworms, try to wash your hands clean to prevent pathogens from infecting the silkworms.
3. When changing mulberry leaves, the movements should be gentle. You can use a feather or a very soft brush to move them, and clean the box frequently.
4. If during the rearing process a silkworm gets sick and dies, remove it from the box as soon as possible, and at the same time scald the box with boiling water for disinfection to prevent contagion.
As market demand for silk has continued to increase in recent years, silk not only sells relatively well in our country, but some is even exported abroad. Therefore, many people have taken a fancy to this market situation, and more and more people are raising silkworms. Raising silkworms is a good project with low investment and high returns!