Pebrine disease of silkworms is caused by

a. Nosema

b. Plasmodium

c. Dugesia

d. Monocystis

 

The correct answer is a. Nosema.

1. What is Pebrine Disease?
   • Pebrine is a serious disease that affects silkworms, causing high mortality rates in silkworm larvae. This disease significantly impacts the production of silk.
2. Causative Agent of Pebrine Disease:
   • Pebrine disease is caused by a microsporidian parasite called Nosema bombycis.
   • Nosema is a type of protozoan that infects the silkworm's body, especially its intestines and tissues, leading to a breakdown of their health and eventually their death.
3. Transmission of Nosema:
   • The disease spreads through contaminated eggs, infected larvae, and even through fecal matter from sick silkworms.
   • The infection usually begins when silkworms ingest the spores of Nosema from contaminated food or their environment.
4. Symptoms of Pebrine Disease:
   • Infected silkworms show symptoms such as reduced growth, sluggishness, and discolored bodies (often pale or yellowish).
   • They may also suffer from digestive problems, leading to high mortality in silkworm populations.
5. Why the Other Options Are Incorrect:
   • b. Plasmodium: This is the causative agent of malaria, which affects humans and other animals, but it does not affect silkworms.
   • c. Dugesia: Dugesia is a type of planarian flatworm, not related to silkworm diseases.
   • d. Monocystis: This is a parasite that affects earthworms, not silkworms.

• Control of Pebrine Disease:
  • The best method to control pebrine disease is by using healthy silkworms that are free from Nosema infection.
  • Infected silkworms should be isolated and discarded, and the environment should be kept clean and free of contaminants.
  • Additionally, breeding silkworms in controlled environments, such as using disease-free eggs, can help prevent the spread of the disease.

Nosema infection in silkworms can be devastating for silk farmers. Proper hygiene, quarantine measures, and the use of disease-free breeding stock are essential to controlling this parasitic infection.