Protozoan Disease of silkworm

1. SER 606 – Diseases of Silkworm
and Their Management (2+1)
Protozoan Disease
By,
Tamilselvi.V
2018641904

2. PEBRINE DISEASE
 First discovered in Francein 1845
 The name pebrine was coined by
De Quadrefagues(1860)
 In Bengali – KATA or MATHA KATA
 In Kannada – GANTU ROGA
 Source of infection – food contaminated with spores

3. Etiology
 Haemtozoid – Pathogen 1st observed in Haemolymph
of silkworm
 Naegeli (1857) named it as Nosema bombycis
Taxonomic position
 Phylum : Protozoa
 Order: Microsporidia Balbiani (1882)
 Family: Nosematidae Labbe (1899)
 Genus: Nosema
 Species: bombycis

4. PATHOGENS
Several microsporidians are knowm to cause the
disease in silkworm.
 Nosema bombycis
 Pleistophora sp.
 Thelohania sp.
 Varimorpha sp.
 Leptomonas sp

5. Morphology

7. Symptoms
Egg:
Transovarian transmission
Lack of uniformity in shape
Reduction in size & weight
Eggs laid in clumps
Poor egg attachment
High % of unfertilized eggs

8. Larva :
 2nd &3rd instar – Wrinkled worms
 4th &5th instar – spotted silkworm, pepper like
irregular spots appearing on the body
 Transovarial transmission – irregular moulting &
growth
 Progress of the disease is slow paced & it takes 2-3
weeks for an infected worm to die

9. Pupa:
 Cocoons- Flimsy, malformed & less coloured
 Thin end & less raw silk content
 The abdomen softens & irregular black spots appear
on the body wall
 May fail to attain adult

10. Moth:
 Delayed moth emergence
 Clubbed wings
 Black spots on wings
 Dull, naked moths without abdominal scales
 Discolouration & shedding of abdominal scales
 Female moths accessory gland being infected –
loosely adhered eggs
 Lay eggs in clusters

11. Alternate host
 Samia ricini
 Indain tropical Tasar & Muga
 Arctia caja
 Bombyx mandarina
 Spodoptera depravata
 Theophila religiosa

12. Detection methods
Predictive test
Pupal test
Forced eclosion test
Mother moth examination

14. Other techniques
 Corrective test – 2% KOH – 100rpm for 2 mins
 Rearing room dust examination, 0.1-0.2% KOH –
1500 rpm for 3 mins
 Immunological techniques
- double immunodiffusion technique
- slide agglutination test
- monoclonal antibody technique

15. DISEASE RESISTANCE & SUSCEPTIBLE
BREEDS
 Chinese race - most resistant
 European race - most susceptible
 Japanese race are in between the two.
IN INDIA
 C.nichi and Nistari silkworm breeds are most
resistant to pebrine disease compared to others.

16. Prevention & control
 Effective disinfection of rearing house
 Disinfection of incubated eggs
 Allowing a Non – rearing period
 Burying & burning of infected rearings
 Pathogen free mulberry field
 Improved rearing technology
 Timely feeding (Qlty & Qnty)
 Bed cleaning
 Optimum space for bed
 Proper disposal of waste

17. Pebrine spores isolated from silkworm
moth

18. Pebrine affected moth

19. Pebrine affected
silk gland

20. Pebrine affected larva