its very imp for sericulture production

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Study on Integrated Diseases Management
in Silkworm, Bombyx mori L.
ANANTA MUKTYARSING PARIHAR
Msc Agri (Agril.Entomology)
Roll No:PG14-ENT1625
Seminar Topic
DEPT. OF AGRIL. ENTOMOLOGY
DR PANJABRAO DESHMUKH KRUSHI VIDYAPEETH,AKOLA
Under the Guidance of
Dr. D. B. Undirwade
Head Dept.of Agril.Entomology

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INTRODUCTION
 Disease is a condition in which a state of physiological
equilibrium of the host with the environment (i.e.
health) becomes unbalanced.
 Disease usually has a primary cause but there may be
also be a complex web of secondary causes
contributing to disease incidence (pre-disposing
factors) including environmental conditions.
 The major constraints in silk cocoon production are
the occurrence of diseases in silkworm.
 In India, the annual crop loss due to silkworm diseases
is to an extent of 15-20% (Baig & Pradeep Kumar, 1987,
Baig et al., 1990).
Contd….

4. 4
In addition to different pathogens, viz. viral, bacterial
fungal and protozoan, environmental and nutritional
factors also play a significant role towards susceptibility of
the host to infection and development of diseases.
No individual preventive measure is sufficient to check the
disease incidence and hence an integration of several
innovative measures have been developed for the
management of silkworm diseases.
Contd…

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OBJECTIVE OF THE STUDY
To study the predisposing factors for the cause of
silkworm diseases.
To study the importance of different aspects of
integrated disease management strategy towards
prevention and control of silkworm diseases
Contd…

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PREDISPOSING FACTORS CAUSING
SILKWORM DISEASES
The predisposing factors responsible for
occurrence of silkworm diseases are:
Constitution of the silkworm
Nutritional status
Crowding
Pathogen Load
Environmental factors
Contd…

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DIFFERENT ASPECTS OF INTEGRATED DISEASE
MANAGEMENT
Contd….
DISINFECTION
Disinfection means the selective elimination of
undesirable micro-organisms. In sericulture it is the
destruction or inactivation of disease causing germs. In
sericulture, the commonly used disinfectants are
formaldehyde, chlorine compounds, paraformaldehyde,
slaked lime powder, etc., either individually or in
combinations. Bed disinfectants such as Labex,
Sericilllin, Vijetha, etc . are used. Disinfection is the
single most important aspect of integrated disease
management.

8. IMPORTANCE OF HYGIENE
Due importance towards strict adherence to
maintenance of hygienic conditions in and around the
rearing house is a prerequisite for a successful cocoon
harvest.
The hygienic conditions are summarized as:
Clean the rearing house and appliances of dust and dirt
with water 5 days before brushing.
Sun dry the appliances in direct sunlight for 6 hours.
Sprinkle 5% bleaching powder in slaked lime
surrounding the rearing house once in 2-3 days
Avoid injury to diseased larvae.
After bed cleaning, wipe the floor with 2% bleaching
powder in 0.3% slaked lime.
8Contd..

9. Provide optimum bed space and keep the bed dry.
Before entering into the rearing house, disinfect the hands
by washing in dettol water or 2% bleaching powder solution
in 0.3% slaked lime.
Disinfect the feet by walk over 5% bleaching powder in
slaked lime on a foot mat at the entrance of rearing room.
Pick up diseased/ unequal/ suspected diseased worms before
bed cleaning every day using forceps or chawki stick and
dispose them into 5% bleaching powder in slaked lime in a
basin.
Pick the diseased or dead larvae and flimsy cocoons from the
mountage and burn them.
9Contd…

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1st
inst. 2nd
inst. 3rd
inst. 4th
inst. 5th
inst.
Temp. (º C) 27-28 27-28 26-27 24-25 23-24
R.H. (%) 85-90 85-90 80-85 75-80 70-75
SILKWORM REARING MANAGEMENT
Location of Rearing House:
Orientation of the room should be such that the interior is
protected from the direct sunlight, as it is harmful to worms.
The best orientation of rearing room will be north and south,
the room should be with proper ventilation.
Env. Cond. of the Rearing House (Temp. and R.H.):
The optimum Temperature and Humidity for Silkworm
rearing
Contd…

11. Photoperiod:
Provision of 16 -18 hours of light and 6 - 8 hours of
darkness in rearing room is essential.
Air:
The rearing room should be well ventilated to
circulate fresh air.
Spacing:
The recommended spacing of rearing bed
Instar Spacing in Sq. ft.( for 100dfls)
I 6-18
II 18-54
III 54-100
IV 100-200
V 20-400 11Contd…

12. BED CLEANING:
Bed cleaning should be done with proper mesh size of net as
per the stage. Recommended bed cleaning is once in 1st instar
and twice in 2nd instar and from 3rd stage daily in the morning
hours.
CARE DURING MOULTING
When 90% of the larvae settled for moulting no feeding to be
given to worms. Slaked lime to be dusted to reduce bed
humidity. Rearing bed maintained as thin to reduce bed
humidity.
12Contd…

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MOUNTING DENSITY & ENVIRONMENT
The recommended mounting density for Multi X Multi hybrid
is 60 larvae / sq. ft, for Bi X BI hybrid 40 larvae/ sq. ft, and
for multi X Bi hybrid is 50 larvae/Sq. ft.
MOUNTING ENVIRONMENT
Proper environment in the mounting room should be
maintained to get a good crop (24 - 25°C ,60 – 70 % R.H.).
HARVESTING AND STORAGE OF LEAVES
Harvesting should be done during cooler hours of the day.
The leaves should be properly preserved in leaf chamber,
covered with wet gunny cloth. The leaf moisture could be
retained by spraying water over the leaf at frequent intervals
during summer
Contd…

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SELECTION OF SILKWORM BREED
During favourable condition, under West Bengal condition it
is advisable to rear Multi X Bi hybrids and during
unfavourable condition Multi X Multi.
SELECTION OF IMPROVED MULBERRY VARIETY AND
QUALITY OF LEAVES
Choice of mulberry variety for silkworm rearing is very
important for harvesting a good crop. S- 1 and S- 1635 is
widely being practice by the sericulture farmers due to its
qualitative and quantitative features. The mulberry leaf is
the exclusive food of the silkworm Bombyx mori, L. and it is
essential that mulberry leaves are good and of suitable
quality for the silkworm. Leaf quality is the major contributor
for the successful rearing and quality of cocoon produced.
Contd…

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SILKWORM DISEASE SURVEY AND DISEASE
SURVEILLANCE
Most of the silkworm diseases are season specific, hence
Forewarning system of diseases should be there for
effective and timely management of diseases.
CONTROL OF MULBERRY PESTS
Incidence of different diseases in silkworm may be due to
various sources of secondary contaminations including
alternate hosts in and around mulberry garden.
It is essential to control mulberry pests not only to increase
the yield and quality of mulberry but also to prevent
silkworm diseases.
Contd…

16. DISEASE DIAGNOSIS
Early detection of silkworm disease is an important step in
management of disease
Generally in silk worm develops their disease symptoms at
the late stage of disease development
The period left between the development of characteristic
symptoms and death is to short to adopt the curative
measures.
Early detected of diseases during rearing and curative
measure should be taken at early stage to avoid secondary
infection.
16Contd…

17. CONSTRAINTS IN MANAGEMENT OF
DISEASES IN SILKWORM REARING
The major constraint in silkworm disease management is the
need for a disinfectant suitable to the infrastructural
facilities available with sericulturists
Most of the farmers do not have rearing houses as per
required standard
Non adoption of required hygienic condition to be
maintained during the course of rearing
 Unavailability of technology which could diagnose disease
incidence during early stage of infection.
A code of conduct for rearing of silkworm needs to be
adopted to ensure survival of silkworm and to get good
cocoon crop
17Contd…

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Disease Management :: Mulberry
Silkworm
DISEASES OF MULBERRY SILKWORM
Viral Disese
Bacterial Diseases
Fungal Diseases
Protozoan disease : Pebrine

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1. Viral Disese
Grasserie Flacherie

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Symptoms:
The larvae will be sluggish with swollen intersegmantal region
The integument of diseases larvae will be fragile and brakes
easily
On infury milky fluid containing many polyhedral inclusion
bodies oozes out from the larval body
The diseases larvae do not settle for moult and showshining
integument
The larvae appear to be restless
The dead larvae hand by hind legs head downward

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Management
1.Sun drying of rearing appliances for one/two days
2.Disinfection of rearing room and appliances with 5% bleaching
powder
3.Disinfection of worms, trays and discarding of diseased worms
4.Ensure proper ventilation and air circulation
5.Provide proper bed spacing
6.Feed the larvae with nutritious mulberry leaves
7.Collect and burn infected larvae, faecal matter and bed refuses
8.Early diagnosis and rejection of infected lots
9.Dust the bed disinfectant, Vijetha (or) Resham Keet Oushadh on
the larvae, after each moult and ½ hr. before resumption of
feeding (3 kg/100 dfl).
10.Spray 1% of extract of Psoralea coryleifolia on mulberry leaves,
shade dry and feed worms once during third instars.

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2. Bacterial Diseases
Bacteria and viruses cause the disease individually or in
combination.
Fluctuating temperature and humidity and poor quality
mulberry predispose the disease development.

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Symptoms:
The diseased larvae will be stunted in growth, dill
lethargic soft and appear flaccid
The cephalothoracic region may be translucent
The larvae vomit gut juice, develop dysentery and
excrete chain type fecus.
The larvae on death putrefy, develop different and emit
foul smell

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Management
1.Maintenance of hygienic condition
2.Disinfection of rearing room and appliances
3.Disinfection of worms, trace and discarding of sick worms
4.Avoid injury to the worms, overcrowding of trays and
accumulation of faeces in the rearing bed
5.Sound management, improving the rearing environment and
feed stuff
6.Feeding the larvae with healthy nutritious leaves.
7.Early diagnosis and rejection of infected lots
8.Avoid spraying commercial B. t. insecticides in nearby mulberry
field.
9.Apply antibiotics like Streptomycin/Tetracyclin/Ampicillin

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3. Fungal Diseases
Muscardine

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White muscadine is caused by a fungus Beauveria bassiana and
the green muscadine is caused by a fungus Spicaria prasina.
Aspergillosis is common in young age silkworms and the
infected larvae will be lustrous and die. Dark green (Aspergillus
flavus) or rusty brown ( Aspergillus tamari)mycelial cluster are
seen on the dead body.

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The diseases larvae prior to death will be lethargic and on
death are flaccid
oil specks may be seen on the surface of larvae
They gradually be fome hard, dry and mummify into a white
or green coloured structure
The diseases pupae will be hard, lighter and mummifies
Symptoms:

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Magagement
1.Sundry the rearing appliances.
2.Disinfect the rearing room and utensils with 5 per cent
bleaching powder
3.Avoid low temperature and high humidity in the
rearing room
4.Keep the rearing bed thin and dry
5.Early diagnosis and rejection of infected lots
6.Apply Dithane M45 (3 kg/100 dfls) / Vijetha
supplement as disinfectant on the larvae
7.Disinfect rearing rooms and trays with 4 per cent
pentachlorophenol to control Aspergillosis.

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4. Protozoan disease
Pebrine
Diseases larvae show slow growth, undersized body and poor
appetite.
Diseases larvae reveal pale and flaccid body. Tiny black spots
appear on larval integument.
Dead larvae remain rubbery and do not undergo putrefaction
shortly after death.
Symptoms:

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Management
1.Produce healthy eggs
2.Disinfection of rearing room and utensils
3.Maintain strict hygienic conditions during rearing
4.Surface disinfect the layings in 2 per cent formalin for
10 minutes before incubation.
5.Collect and burn the diseased eggs, larvae, pupae and
moths, bed refuses, faecal pellets, etc

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For this study two rearings were conducted during July –
September, 2011 (unfavourable season).
There was one treatment and one control batch and each
having 3(three) replications.
After 1st
moult 150 healthy worms for the 1st
rearing and 200
worms for 2nd
rearing for each replication in the treatment and
control were selected.
Two multivoltine breeds were taken for the study; Nistari (M)
for the 1st rearing and M12 (W) for the second.
Frequency of feeding was four times a day; at 6 am, 10 am, 4
pm and 8 pm.
Labex was used as the bed disinfectant in the treatment and
applied as per recommendation.
Technology in respect to Package & Practices developed by
Silkworm Physiology & RTI section of this institute was
adopted for the treatment lot.
Contd…

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RESULTS
Results from the two rearing conducted are depicted in
Table 1, 2 and 3. The results showed that in the treatment,
in which integrated approach towards management of
silkworm diseases were adopted caused significant
reduction in mortality due to diseases against the control in
both the rearings conducted.
Contd…

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Table: 1. Comparative Rearing Performance (July-Aug’11)
Race: Nistari (M) Date of Brushing: 11.07.2011
Treatment/
Replication
No. of
larva
kept
Larval Mortality
(%)
Total
mor-
tality
(%)
Wt. of
10
matur.
larvae
ERR
%
(by
no)
Yield/
100
dfls
(by
No.)
Gra Fla M
u
s
Total
T
Rep- I 150 2.0 8.66 0 10.66 15.33 27.02 76 30400
Rep- II 150 0 6.66 0 6.67 12.0 26.67 81 32533
Rep-III 150 2.66 10.67 0 13.33 22.0 26.64 75 19866
Average 150 1.55 8.66 0 10.22 16.44 26.77 77 30933
C
Rep- I 150 10.67 11.33 0 22.0 30.0 24.63 63 25333
Rep- II 150 6.67 8.66 0 22.0 30.0 24.63 63 25333
Rep-III 150 8.0 8.66 0 16.66 23.33 25.62 66 26400
Average 150 8.45 9.55 0 18.0 24.66 25.38 66 26311Contd…Gain % (by No) = 17.56 %

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Table: 2. Comparative Rearing Performance (Aug-Sep’11)
Race: M 12 (w) Date of Brushing: 08.08.2011
Treatment/
Replication
No. of
larva
kept
Larval Mortality
(%)
Total
mora
lity
(%)
Wt. of
10
matur
ed
larvae
ERR
%
(by
No)
Yield/
100
dfls
(by
No.)
Gra Fla M
us
Total
T
Rep- I 200 0 9 0 9 12.5 22.98 60 23800
Rep- II 200 0 10 0 11 15.0 23.97 55 22000
Rep- III 200 1 8.5 0 8.5 13.5 22.20 51 20200
Average 200 0.33 9.17 0 9.50 13.7 23.05 55 22000
C
Rep- I 200 1.0 17.5 0 18.5 23.5 22.04 44 17600
Rep- II 200 0 19.5 0 19.5 26.5 21.64 45 18000
Rep- III 200 0 18 0 18 27.0 22.02 41 16200
Average 200 0.33 18.33 0 18.67 25.7 21.90 43 17267Contd…Gain % (by No) = 27.41 %

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RESULTS
The reduction in total mortality (larval and pupal) was 8.22%
and 12% respectively during the 1st
& 2nd
rearing.
ERR was also higher in the treatment than in the control; 77
% in treatment against 66 % in control during the 1st crop
and 55 % in treatment against 43 % in control during the
2nd crop.
 Yield gain (by No.) was recorded to be 17.56 % in the first
crop and 27.41 % in the second crop.
This difference in yield gain may be attributed to the
difference in the two multivoltine breeds selected for the
study and it may be inferred that during unfavourable
condition M12 (W) is a better performer than Nistari (M).
However post cocoon characters did not show any significant
variation between the treatment and control.
Contd…

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DISCUSSION
The findings from our study are in agreement with those of
Deviah (1986), Liu and Zhong, (1988). Results from our study
revealed that higher ERR was achieved in the treatment
against the control in both the crops conducted during
unfavourable seasons. This was achieved by integration of not
a single but a multitude of approaches viz. proper disinfection
of the rearing room and appliances, use of bed disinfectant,
spacing as per recommendations, selection of breeds for
unfavourable season etc.
Prevention is better than Cure” is the correct approach and
that should be adopted in integrated disease control. This
means that one should go about actively preventing disease
before it occurs, and it is only when preventive measures are
in force that we can hope to effectively control the occurrence
and spread of disease.
Contd…

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