Technical measures to prevent the production of inferior cocoons in silkworm rearing

In silkworm rearing, selecting high-yield and high-quality cocoons is the key to a bountiful harvest. During the silkworm feeding process, many factors can produce large numbers of inferior cocoons and reduce @#@250@#@ benefits. In order to avoid producing inferior cocoons, increasing the rate of good cocoons and reducing the rate of inferior cocoons is an important step in further increasing the economic benefits of silkworm farmers. The relevant technical points for preventing inferior cocoons are briefly introduced as follows:

1 Strengthen feeding management

1.1 Rear young silkworms under plastic film mulching, which both keeps mulberry leaves fresh and encourages the larvae to feed readily, helping the larvae to eat their fill of good mulberry leaves, improve larval constitution and enhance disease resistance.

1.2 After finishing the collection of newly hatched silkworms, feed leaves promptly. When molting and emergence are uneven, rear them in batches. When rearing older larvae, it is advisable to feed thinly and frequently to achieve sparse distribution and ensure the larvae eat their fill.

1.3 Because silkworms are reared in the same place for a long time, pathogens accumulate heavily and spread widely; therefore, thorough disinfection must be carried out and disinfection work done well. Method: first clean, then scrub and disinfect. Spray indoors and outdoors with a bleaching powder solution prepared to a concentration containing 1% available chlorine.

1.4 Hot, stuffy weather is most harmful to larvae that are about to molt, molting, or about to emerge. Therefore, when rearing older larvae, the doors and windows of the rearing room should be opened frequently for ventilation, which benefits larval growth and development.

1.5 If long periods of high temperature and dryness occur, frequently spray cool water on the walls. Give the larvae more water-containing leaves and thin leaves, feed frequently, and ensure fresh leaves at every feeding.

1.6 If low temperature and high humidity occur, heat the room and remove moisture, and open the windows in time for ventilation. The rearing bed should be sparse, and silkworm droppings should be removed frequently. Feed mulberry leaves with low moisture content.

1.7 In stuffy, hot weather before rain, open the windows for ventilation and feed fresh mulberry leaves. During rainfall and strong wind, close the doors and windows promptly; after the wind weakens a little, open the doors and windows again for ventilation to ensure a good habitat for the larvae.

2 Prevent the production of inferior cocoons

2.1 Double cocoons

2.1.9 Cause When the larvae spin cocoons, too many mature silkworms are placed on the cocooning mount, artificially causing two or more mature silkworms to crowd together and make double cocoons.

2.1.2 Harmfulness The silk filaments of such cocoons are tangled, the reeling rate is low, reeling is difficult, the silk quality is coarse and the quality declines; such cocoons can only be purchased as inferior cocoons.

2.1.3 Preventive measures When mature silkworms are placed on the mount, use square mounts or plastic folding mounts, place them on the mount when properly mature, give each mature silkworm one cocooning position, do not let mature silkworms become too old before mounting, and mount them in time.

2.2 Thin-shelled cocoons

2.2.1 Cause During the larval stage they did not eat their fill of good mulberry leaves, so the larvae produced less silk. During the cocoon-spinning period, indoor humidity was high and the temperature was on the high side, causing the best spinning time of the mature silkworms to be missed and resulting in thin-shelled cocoons.

2.2.2 Harmfulness Because the cocoon shell is soft and spongy and the cocoon layer is loose and thin, it cannot be reeled or yields little silk.

2.2.3 Preventive measures Ensure the larvae eat their fill of good mulberry leaves and prevent mounting while hungry. During the larval stage, pay attention to disease prevention, improve larval health, and prevent diseased larvae from being mounted. For wandering silkworms on the mount and mature silkworms that fall to the ground, pick them up promptly, wash them with clean water, and place them on a new mount, to prevent excessively high indoor temperature and excessively high humidity.

2.3 Perforated cocoons

2.3.1 Cause Due to improper fly prevention during the larval stage, @#@261@#@ cocoons are produced; during the cocoon-spinning period of mature silkworms, high temperature and high humidity cause mature silkworms to bite through the cocoon shell, resulting in one or two perforations in the cocoon.

2.3.2 Harmfulness Because the silk in such cocoons is broken, they cannot be reeled normally, and this also affects the economic benefits of silkworm rearing.

2.3.3 Preventive measures Do good fly prevention work during the larval stage to prevent maggot-infested cocoons; in the cocoon-spinning room, prevent high temperature and high humidity, and avoid stuffy heat that causes mature silkworms to bite through the cocoon shell and emerge, resulting in perforated cocoons.

2.4 Contaminated cocoons

2.4.1 Cause Mature silkworms in the mount are too dense, mature silkworm droppings and urine are not removed in time, and diseased mature silkworms are mounted, causing contamination inside and outside the cocoon shell and forming yellow spots on the surface of the cocoon shell.

2.4.2 Harmfulness When such cocoons are reeled, tangled silk is produced, the silk quality is relatively poor, and the quality is low.

2.4.3 Preventive measures After the cocoon shells of mature silkworms in the mount have formed, promptly remove mature silkworm droppings and bedding paper, and keep the room at a suitable temperature and dry; during the larval stage, prevent diseases well and prevent diseased mature silkworms from being mounted, avoiding contamination of the cocoon shell after mature silkworms die; when harvesting cocoons, harvest and place them gently to prevent bruising the pupae inside the cocoons, which would cause pupal fluid to contaminate the cocoon shell.

2.5 Wood-mark cocoons

2.5.1 Cause Wood-mark cocoons are produced by cocoon mount materials that are too hard and mature silkworms being too dense on the mount.

2.5.2 Harmfulness Such cocoons cannot be reeled; even if reeled, the silk yield is low.

2.5.3 Preventive measures Avoid using hard materials such as wheat and rice straw as cocoon mounts; choose square mounts or plastic folding mounts as cocoon-spinning mounts to increase the rate of superior cocoons, and place mature silkworms according to the standard capacity of the mount, keeping mature silkworms in the mount from being too dense.

2.6 Hairy-footed cocoons

2.6.1 Cause The larvae suffer from disease during the larval stage and cannot pupate normally after spinning cocoons, becoming diseased dead hairy-footed cocoons.

2.6.2 Preventive measures Harvest cocoons at the proper time.

2.6.3 Identification method Take a sample cocoon and shake it; a crisp sound indicates that pupation has finished. You can also cut an opening in the cocoon with scissors; if the pupa body has turned yellow-brown, it is the proper time to harvest cocoons; otherwise, they are hairy-footed cocoons.

2.7 Avoid mixing cocoons

When harvesting cocoons, spread good cocoons and inferior cocoons separately to improve cocoon quality, ensure high-quality delivery of cocoons, and strictly prevent harvesting and selling mixed-grade cocoons, which would cause adverse economic losses.