Detailed Explanation of Silkworm Disease Prevention and Control Methods and Technical Points

Silkworm diseases originally occurred mainly as midgut-type nuclear polyhedrosis and empty-headed flacherie, but at present, due to differences in @#@250@#@ time and climatic conditions, silkworm diseases such as blood-type nuclear polyhedrosis and muscardine are predominant.

1. Blood-type nuclear polyhedrosis (commonly known as climbing silkworm, granny silkworm)

The virus of blood-type nuclear polyhedrosis parasitizes in the blood of diseased silkworms. The blood of healthy silkworms is colorless and transparent, while the blood of diseased silkworms is milky white, so diseased silkworms are also called granny silkworms. Once a silkworm develops the disease, as the condition worsens, the diseased silkworm drags milky white purulent fluid and crawls frantically, so it is also called climbing silkworm. By crawling, diseased silkworms spread large amounts of virus onto mulberry leaves and the rearing bed, causing healthy silkworms to become infected and develop the disease after eating virus-contaminated mulberry leaves.

1. Main causes of onset. Due to incomplete disinfection, virus persists; mulberry leaves are too tender with high water content; the rearing environment is hot and humid; stuffy heat and improper handling of molting and arousal cause healthy silkworms and diseased silkworms to be reared together and infect each other.

2. Prevention and control methods. Before each feeding of mulberry leaves, pick out the diseased silkworms with milky white bodies that crawl frantically and put them into a container with lime for unified deep burial, then wash hands and use fresh lime powder to disinfect the silkworm bodies and rearing bed, 1-2 times a day. During rearing, pay attention to mulberry leaf maturity, do not feed tender leaves or immature leaves (for the first instar, use the 2nd-3rd leaves of new shoots; for the second instar, use the largest leaf of new shoots; for the third instar, use three-eye leaves; for the fourth instar, use whole bud leaves), and pay attention to indoor ventilation. During molting of the 1st-2nd instars, there should be air convection windows in the rearing room; for the 3rd-4th instars, indoor air should circulate; for the 5th instar, doors and windows should be opened for rearing. If encountering rainy days and wet mulberry leaves, even more attention should be paid to opening doors and windows for rearing.

2. Muscardine

The conidia of muscardine (white fuzz) are brought in by wind, mulberry leaves, and other external factors. After landing on the silkworm body, they penetrate into the silkworm body after 10-12 hours, absorb the silkworm's nutrients and water to maintain life, and after one day emerge from the silkworm body to generate hyphae and conidia, which then infect healthy silkworms.

1. Causes of onset. The presence of muscardine conidia, plus high air humidity, is conducive to the growth of muscardine conidia. It generally occurs easily in rainy spring, summer, and late autumn periods.

2. Prevention and control methods. Promptly eliminate diseased silkworms, grasp and remove them before the diseased silkworm corpses turn white to prevent infection. The removed diseased silkworms should be uniformly burned or deeply buried. During rearing, promptly eliminate late-molting silkworms and non-molting silkworms, and at the same time do a good job in disinfecting the silkworm bodies and rearing bed during the susceptible periods of newly hatched silkworms, newly molted silkworms, and mature silkworms.

Prevention and control for mild outbreaks: In addition to routine disinfection of silkworm bodies and rearing bed for newly hatched silkworms and newly molted silkworms, persist in once-a-day disinfection of silkworm bodies and rearing bed during the fifth instar, and scatter more charred chaff lime during molting to keep the rearing bed dry.

Prevention and control for severe outbreaks: In addition to routine disinfection of silkworm bodies and rearing bed for newly hatched silkworms, newly molted silkworms, and mature silkworms, persist in twice-a-day disinfection of silkworm bodies and rearing bed during the fifth instar, and change the covering material during molting from lime to anti-muscardine powder.

Special effective agents for muscardine prevention and control include: "Miejiangling" anti-muscardine powder, "Youlüjing" anti-muscardine powder, antibacterial agent "402". "Xunxiaojing" can also be used for fumigation disinfection, and during the large silkworm stage, "Xiaoteling" 200-fold liquid spray disinfection can also be used.