What are the characteristics of silkworm disease prevention and control? A detailed explanation

(1) Wide range of infection sources

1. Infection sources during @#@250@#@: diseased and dead silkworms, pupae, and moths during sericulture, as well as their pathogen-carrying feces, silkworm litter, old mountages, and rotten cocoons, are serious sources of silkworm disease infection.

2. Cross-infection with field insects: diseased field insects, insect carcasses, and insect feces contaminating mulberry leaves are another source of silkworm disease occurrence.

3. Pathogen accumulation and toxic contamination in the sericulture environment.

(2) Poor feeding and management, weak silkworm constitution makes them susceptible to disease

1. Not paying attention to disinfection, working carelessly; or only paying attention to spring silkworm disinfection while neglecting summer and autumn silkworm disinfection; only paying attention to disinfection before sericulture while neglecting disinfection during or after the silkworm rearing period; or only paying attention to disinfection while neglecting disease prevention.

2. Poor feeding and management, extensive sericulture. During sericulture, not paying attention to molting and rising treatment, not paying attention to separating and grouping by developmental stage, or uneven mulberry feeding and other human factors create weak and small silkworms, weakening the silkworm constitution and making them susceptible to disease. Some habitually remove litter by hand, with rough handling, causing injury to the silkworms and increasing the chances of silkworms suffering from nuclear polyhedrosis and septicemia.

3. Sericulture facilities cannot keep up, and production often sees poor planning, imbalanced mulberry-to-silkworm ratio, or insufficient sericulture equipment and overcrowded silkworms; large and small silkworms reared in the same room, with large and small silkworm tools mixed; or mulberry leaves stored in the silkworm room; or overcrowding during the silkworm period, with insufficient time between rearing batches for cleaning and disinfection.

(3) Poor leaf quality, leading to weak silkworm constitution or poisoning, reducing disease resistance

1. Poor mulberry orchard management, or excessive nitrogen fertilizer application, resulting in low leaf quality.

2. In mulberry orchards with abundant fertilizer and water, or when summer mulberry trees grow excessively, the leaf quality is not mature enough, with excessively high water content and relatively low sugar and protein. After silkworms eat them for a long time, their constitution becomes weak and disease occurs.

3. Mulberry trees affected by air pollution cause chronic poisoning after silkworms eat them, with severe cases resulting in poisoning death, and mild cases causing poor development and low disease resistance.

(4) Poor quality or improper use of sericulture drugs

(5) Harsh climatic conditions often become important triggers for some major silkworm diseases. The temperature range for normal silkworm growth is 20-30°C; below 15°C and above 30°C are both extreme temperatures that easily induce silkworm diseases. The suitable temperature for the 4th-5th instar period is 22-24°C, with relative humidity of 70-75%. In production practice, summer and autumn temperatures often reach as high as 33-35°C, affecting the physiological functions of silkworms and causing a decline in disease resistance. Large silkworms eat more mulberry, accumulate more water in their bodies, and have relatively less body surface area than small silkworms, making heat dissipation difficult. Therefore, when large silkworms encounter high temperatures, they are more likely to be induced to various silkworm diseases, such as cytoplasmic polyhedrosis, densonucleosis, viral flacherie, etc. Moreover, high-temperature and high-humidity environments are more conducive to the reproduction of some pathogenic microorganisms, leading to increased environmental pathogen density, increasing the chances of silkworm infection.