DISEASES OF MULBERRY SILKWORM Quiz

Explore the main diseases affecting mulberry silkworms, their symptoms, and proven management techniques used in sericulture. Review the key features of viral, bacterial, fungal, and protozoan infections along with practical control measures.

1. Symptoms of Grasserie in Silkworms

   Which of the following symptoms is most characteristic of Grasserie, a viral disease in mulberry silkworm larvae?

   1. Larvae display tiny black spots and poor appetite.
   2. Larvae develop chains of feces and emit foul smell after death.
   3. Larval bodies become dry, hard, and mummified into white or green structures.
   4. Larvae are sluggish with swollen intersegmental regions and milky fluid oozes on injury.

   Explanation: Grasserie presents with sluggish larvae showing swollen intersegmental regions, and a milky fluid rich in polyhedral bodies oozes if the body breaks. Chains of feces and foul odor indicate bacterial disease. Mummification with color changes points to fungal infections. Tiny black spots and poor appetite are typical of Pebrine, a protozoan disease.

2. Proper Disinfection for Viral Disease Management

   Which is a recommended management practice for controlling viral diseases such as Grasserie in mulberry silkworms?

   1. Applying antibiotics like Streptomycin directly to larvae.
   2. Spraying commercial B. t. insecticides on mulberry fields.
   3. Disinfecting rearing room and appliances with 5% bleaching powder.
   4. Surface disinfecting layings with formalin solution.

   Explanation: Disinfecting rooms and appliances with 5% bleaching powder helps prevent and manage viral diseases. B. t. insecticides are not for viral diseases and may harm silkworm larvae. Antibiotics target bacterial, not viral, infections. Formalin disinfection is for preventing Pebrine, a protozoan disease.

3. Fungal Disease Identification

   What is a distinguishing feature of fungal infections like muscardine in mulberry silkworms?

   1. Larvae develop translucent cephalothoracic regions and vomit gut juice.
   2. Infected larvae gradually become dry, hard, and mummified with white or green coloration.
   3. Larvae reveal swollen, fragile integument and shiny appearance.
   4. Larvae remain rubbery after death without putrefaction.

   Explanation: Fungal infections, such as muscardine, cause larvae to become hard, dry, and mummify with specific coloration. Translucence and gut juice are linked to bacterial diseases. Swollen, fragile integument and shine are signs of viral disease. Rubber-like post-mortem texture is seen in Pebrine.

4. Bacterial Disease Prevention

   Which management practice helps reduce bacterial diseases in mulberry silkworms?

   1. Feed larvae with shade-dried mulberry leaves only during third instar.
   2. Avoid injury to worms and accumulation of faeces in the rearing bed.
   3. Spray Psoralea coryleifolia extract on mulberry leaves.
   4. Surface disinfect layings with 2% formalin for 10 minutes.

   Explanation: Preventing injuries and frequent cleaning reduces bacterial infections by limiting their spread and entry points. Psoralea coryleifolia extract is specific for viral management. Feeding shade-dried leaves in third instar is a viral disease suggestion. Formalin disinfection of layings controls Pebrine, a protozoan disease.

5. Symptoms of Pebrine Disease

   Pebrine disease in mulberry silkworms is best characterized by which of the following symptoms?

   1. Milky fluid oozing from larval body after injury.
   2. Vomiting gut juice and excreting chain-type feces.
   3. Oil specks on larval surface and transformation into white mummies.
   4. Slow growth, undersized body, and tiny black spots on the integument.

   Explanation: Pebrine shows slow larval growth, undersized bodies, and tiny black integument spots. Vomiting gut juice and chain feces signify bacterial disease. Oil specks and white mummification are signs of fungal infections. Milky fluid leakage is typical of viral Grasserie.

6. Causes of Bacterial Diseases

   Which factor is most likely to predispose mulberry silkworm larvae to bacterial diseases?

   1. Early rejection of infected lots.
   2. Strict maintenance of hygienic conditions.
   3. Sun-drying of rearing appliances for several days.
   4. Fluctuating temperature and humidity with poor quality mulberry leaves.

   Explanation: Bacterial diseases are more likely to develop under bad rearing conditions such as fluctuating environment and substandard feed. Maintaining hygiene, early rejection, and sun-drying are practices that reduce disease risk rather than increase it.

7. Management of Muscardine

   Which is a recommended method to control the spread of muscardine fungal infection in silkworm rearing?

   1. Feeding worms with Psoralea coryleifolia extract during the third instar.
   2. Applying antibiotics like Tetracyclin on the larvae.
   3. Disinfecting rearing rooms and trays with pentachlorophenol.
   4. Spraying B. t. insecticides in nearby mulberry fields.

   Explanation: Pentachlorophenol disinfection is suggested for controlling Aspergillosis type fungal infections. Psoralea coryleifolia extract is used against viral diseases. Antibiotic treatment is for bacterial problems, and B. t. insecticides are not recommended near silkworm rearing.

8. Protozoan Disease Prevention

   What is an effective method to prevent the transmission of Pebrine in silkworm rearing?

   1. Feeding larvae only after the fourth moult.
   2. Providing increased ventilation and bed spacing.
   3. Administering antibiotics like Ampicillin to larvae during rearing.
   4. Surface disinfecting the layings in 2% formalin for 10 minutes before incubation.

   Explanation: Formalin disinfection of egg layings can help prevent Pebrine by eliminating protozoan contamination before hatching. Antibiotics are ineffective against protozoa. Ventilation and bed spacing help with other diseases, not specifically with Pebrine. Feeding timing is not related to Pebrine control.