Pebrine disese

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 1 st 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

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

7. Larva : 2 nd &3 rd instar – Wrinkled worms 4 th &5 th 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

8. 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

9. 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

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

11. Detection methods Predictive test Pupal test Forced eclosion test Mother moth examination

12. 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

13. 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.

14. 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

15. Pebrine spores isolated from silkworm moth

16. Pebrine affected moth

17. Pebrine affected silk gland

18. Pebrine affected larva