Flacherie. Flacherie (literally: "flaccidness") is a disease of silkworms, caused by silkworms eating infected or contaminated mulberry leaves. ... Bacterial pathogens contributing to infectious flaccherie are Serratia marcescens, and species of Streptococcus and Staphylococcus in the form known as thatte roga.

1. Department of Zoology
AKASH MISHRA
MSC ZOOLOGY
BBAU

2. INTRODUCTION
 CAUSING AGENT
ROUTE OF INFECTION
ALTERNATE HOST
PATHOGENESIS
PATHOGEN STABILITY
CAUSES OF THE DISEASE
SYMPTOMS
PREVENTIVE MEASURES

4.  Infectious flacherie is highly contagious. Viral
flacherie in silkworm is caused by
picornavirus of family Picarnaviridae.
 Flacherie may be due to virus, bacteria,and
physiological disorders.
 Beside bacteria ,Infectious Flacherie
Virus(IFV),an RNA virus can also cause
Flacherie in the host silkworm where it forms
irregular inclusions mostly in the midgut
goblet cells.

5.  It is caused by the Bombyx mori Infectious
Flacherie Virus (BmIFV) belonging to the
family Picornaviridae.
 Picornaviruses are among the smallest viruses
in the animal kingdom.

6. PICORNAVIRUSES
ELECTRON MICROGRAPH OF PICORNAVIRUS

7. The disease is common
during Summer and Rainy
seasons.

8. Fluctuation in
temperature, high
humidity and poor quality
of leaves.

9.  Silkworm gets infected by eating
contaminated mulberry leaf.
 Dead diseased silkworm, its faecal matter,
gut juice, body fluid are the sources of
pathogen contamination.
 The infection can also take place through
injuries/cuts/wounds.

10.  Infectious flacherie virus
has been observed to
inflict Bombyx
mandarina.
 The pathogen multiplies
in the mid gut epithelium
cells but the larvae
remain healthy.
 Glyphodespyloal is, a
common pest of mulberry
is also a habitual
alternate host for BmIFV
as well as BmDNV.

11. Virus is liberated
freely along with
faecal matter and
contaminates
leaves in trays.
Virus exists freely
in air, water,
mulberry leaves
and dead larvae.

12.  Infection mainly takes place per orally.
 Auto radiographic techniques show that BmIFV
infects the goblet cells of the mid gut by their
ssRNA.The latter further gains entrance into the
nucleus where it replicates to form new ssRNA.
 Later on, the newly formed ssRNA is transferred
to the cytoplasm and together with the viral
protein is assembled into viral particles.
 Infection starts from the anterior region of the
midgut and then progress towards posterior
region.

13. The environmental factors
influence the pathogen stability.
Viral activity is reduced at pH 2
and active between 3-12.
The pH for optimum activity is
6.0.

14. Loss of appetite and translucent
cephalothorax.
Look sluggish and sick with head and
thorax motionless.
Larvae with disproportionately
enlarged head compared to healthy
worms.
Retarded growth and development
followed by shrinkage of the body.

15. Infected larvae evacuate excreta in
chain or string or irregular shaped.
Diarrhoea followed by vomiting
gastric juice.
The body turns transparent and the
gut is filled with brownish fluid.
Some individuals may exhibit rectal
protrusion.

16. Diagnosis by external symptom is
difficult and the disease can be
detected by fluorescent antibody
technique or by staining the
infected cells with pyronine methyl
green.
Latex agglutination and other
serological tests are also being used
for the detection of the disease.

17.  Select races resistant to infectious flacherie .
 Young silkworms are reared co-operative
units under strict hygienic condition.
 The diseased larvae should be picked up and
destroyed.
 Feed with nutritious mulberry leafs to keep
sound health. Too mature leafs at early
instars and tender leafs and later instars
should be avoided.
 Soiled and diseased leaves moist with
raindrops should also be avoided for feeding.

18. Provide favourable environmental
conditions during rearing.
The diseased larvae with bed refuse
should be burnt or put in manure pit
for through decomposing .
The faecal and litter of diseased
larvae are pilled in a manure pit for
decomposition.