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Government Of Assam Handloom Textiles & Sericulture Directorate of Sericulture

Diseases of Silkworm


  • The pebrine disease attacks muga silkworm during all the season. The intensity of the disease varies in different seasons. During spring and autumn, the incidence of the disease is less because of the favourable climate. The infectivity is higher during summer and winter seasons.
  • The extremely hostile weather of summer months makes the larvae weak and they become susceptible to the disease. A healthy brood somewhat resists the disease in a new environment.

Sources and spread of the disease

  • The disease spreads from the following sources
  • The rearers do not use disease free certified seed and hence muga crop loss due to pebrine is quite common.
  • Contaminated egg laying kharika.
  • During the period of hatching, the larva gets infected from the egg shell.
  • Consumption of contaminated egg shell.
  • Contaminated grainage appliances.
  • Purchase of infected seed cocoons
  • Infected moth
  • Meconium and moth scales.
  • Grainage dust.
  • Through wind and workers in grainage section.
  • Mostly, consumption of contaminated foliage of host plant.
  • Faecal matters of infected larvae.
  • Exuviae of infected larvae.
  • Contaminated foliage.
  • Contaminated rearing site.
  • Contaminated rearing appliances.
  • Gut juice and vomit containing pathogens, which contaminate the rearing environment.
  • Transovarially infected larvae
  • Files and butterflies can carry the parasite infecting the muga larva in outdoor rearing. Such infection is more common in muga and tasar worms.