Detailed Explanation of Key Technical Points for Silkworm Disease Prevention and Control

In the process of rearing silkworms, the occurrence of silkworm diseases is closely related to the constitution of the larvae, pathogens, and environmental conditions. @#@250@#@Farmers who do not thoroughly disinfect the rearing rooms and tools, who manage the rearing period with extensive techniques, and who provide poor environmental conditions create factors unfavorable to larval growth and development. These factors easily lead to invasion by pathogenic microorganisms, causing a decline in larval constitution and resulting in disease, which leads to mass outbreaks of illness in the larvae and causes significant economic losses for silkworm farmers.

To effectively control the occurrence of larval diseases, during the silkworm larval rearing period, prevention must be the priority, combined with control measures, to ensure high quality and high yield. The control measures must achieve the following aspects.

1 Thorough disinfection to eliminate sources of infectious disease

1.1 Cleaning and sanitation

Before rearing silkworms, a comprehensive cleaning and washing of the used premises and silkworm tools must be carried out. Dead silkworm bodies, silkworm excrement, residual silk from cocoons on rearing equipment, and weeds and debris both indoors and outdoors must be thoroughly removed. The floor should be washed with clean water to improve the effectiveness of chemical disinfection.

1.2 Eliminating sources of disease

Eliminating sources of disease is an important measure in the comprehensive prevention and control of larval diseases in silkworm rearing. These sources of disease are the main sources of the most serious diseases that cause severe damage in production. Therefore, thorough disinfection of rearing tools and the surrounding environment must be carried out to eliminate sources of disease and ensure the safety of silkworm rearing.

1.3 Rearing room disinfection

After the silkworm rearing room is cleaned, the floor should be rinsed with clean water, then bleaching powder solution should be used to spray and disinfect the floor, walls, and ceiling. Finally, doors and windows should be closed, and fumigation disinfection should be carried out using Du Xiaosan (a fumigant disinfectant).

1.4 Silkworm tool disinfection

After silkworm tools are washed clean, they should be disinfected with bleaching powder solution. The chemicals must be mixed accurately, and the spray solution must be applied evenly. After disinfection is complete, the silkworm tools should be placed outdoors and exposed to sunlight.

1.5 Eliminating weak silkworms

During the rearing process, strict separation of early-rising silkworms and rearing in batches must be carried out. Late-molting silkworms and small silkworms should be eliminated or reared separately to ensure uniform growth and development of the larval population. Mixing different groups in the same rearing bed should be minimized to prevent infection with silkworm diseases. This is also an important measure for preventing the occurrence of silkworm diseases.

1.6 Disinfection during the rearing period

Before gathering newly hatched silkworms and before the first feeding after molting, larvae during molting and those that have matured should be disinfected separately with silkworm body and rearing bed disinfectants to protect the larval body from viral invasion. During the rearing process, an appropriate amount of quicklime should be used to disinfect the silkworm body and rearing bed.

2 Strengthening hygiene and epidemic prevention to keep the rearing room clean

2.1 The rearing room must be clean

The silkworm rearing room must be kept clean and hygienic. Fallen residual leaves and silkworm excrement after feeding should be promptly swept up. During sweeping, dust should be kept to a minimum.

2.2 Preventing contamination of stored mulberry leaves

The mulberry leaf storage area must be kept clean and hygienic. Disinfection of the storage room should be carried out regularly. At the same time, viruses must be prevented from being brought into the storage room.

2.3 Washing hands before feeding

To prevent hands from carrying pathogens that contact the larvae and mulberry leaves, workers must wash their hands before feeding to ensure the safety of the larvae's leaf consumption.

2.4 Clearing silkworm excrement

Silkworm excrement must be removed promptly. The removed excrement should be piled up in a centralized location far from the rearing room. After removing the excrement, the floor should be disinfected with 0.3% available chlorine bleaching powder and 1% lime slurry.

2.5 Handling diseased silkworms

Eliminated weak and small silkworms and dead diseased silkworm bodies must not be discarded casually. They should be collected and disinfected uniformly every day, then buried deep underground as fertilizer.

2.6 Supplementary feeding for disease prevention

During the rearing period, in addition to using lime and Canzuojing (a rearing bed disinfectant) to disinfect the rearing room, tools, silkworm bodies, and rearing bed, chloramphenicol should also be added to the feed to prevent and control bacterial silkworm diseases. Chloramphenicol must be added to the feed once during the 2nd instar, and twice during the 5th instar.

3 Eliminating pests in the mulberry field to ensure the safety of larval leaf consumption

3.1 Catching and killing pests

Catching and killing pests in the mulberry field is an important measure for ensuring safe production. Therefore, pests in the mulberry field must be caught and killed promptly to prevent pests from eating mulberry leaves and transmitting diseases to silkworm larvae.

3.2 Chemical treatment

When pests in the mulberry field occur in large numbers and mulberry leaves are heavily contaminated, 0.2%-0.3% available chlorine bleaching powder solution can be sprayed on the leaf surface for disinfection.

4 Strengthening technical management to improve cocoon quality

4.1 Good leaves and satiation feeding

During the rearing process, according to the different instars of the larvae, select and pick high-quality mulberry leaves for feeding, ensuring the larvae achieve good leaves and satiation feeding, strengthening their constitution, and obtaining excellent cocoon quality;

4.2 Preventing high temperatures

High-temperature environmental conditions during the young silkworm stage are unfavorable to growth and development. Therefore, the rearing room should achieve "3 sparseness," namely sparse rearing racks, sparse rearing trays, and sparse silkworm density. Do not close the doors and windows of the rearing room; keep the room well ventilated. When high temperatures occur, spray clean water on the floor and walls to lower the temperature.

4.3 Suitable rearing temperature

The suitable rearing temperature for the 1st-2nd instars is 26-27°C, with a wet-dry difference of 0.5°C; the rearing temperature for the 3rd instar is 24-25°C, with a wet-dry difference of 2°C; the suitable rearing temperature for the 4th-5th instars is 22-23°C, with a wet-dry difference of 4-5°C. During the large silkworm stage, the indoor temperature must not be lower than 24°C. When it is below 24°C, close the doors and windows to raise the temperature, while also paying attention to ventilation.

4.4 Preventing starvation

Summer silkworm rearing occurs during the high-temperature season. Mulberry leaves dry and wilt quickly and easily lose moisture, making them unpalatable to the larvae, which can lead to starvation. To maintain leaf moisture, during the 1st-2nd instars, anti-drying paper should be laid in the rearing trays, with plastic film placed on top. For 3rd instar larvae, only cover without laying underneath. After the larvae enter the molting period, remove the plastic film on top to ensure the larvae feed normally and do not starve.

4.5 Keeping mulberry leaves fresh

After harvesting, mulberry leaves should be stored under conditions of relatively high humidity to keep the leaves in a fresh and moist state. If the mulberry leaves are severely wilted, spray clean water half an hour before feeding and feed with moistened leaves.

4.6 Preventing poisoning

To prevent pesticide poisoning of the larvae, people who have come into contact with pesticides and tools that carry pesticides must be prohibited from entering the silkworm rearing room to avoid pesticide poisoning of the larvae.