Sponsored by
NSTMIS Division
Department of  Science and Technology
Government of  India, New Delhi.

Implemented by
Karnataka State Sericulture Research and Development Institute , Bangalore


Technology No. : 062
Organization : Karnataka State Sericulture Research and Development Institute, Bangalore, Karnataka
Subject : Mulberry Sericulture
Category : Silkworm Pathology
Technology Name :

Muscardine Disease Precautionary Measures and Its Control

Personnel : Veeranna G, Geetha Bai M, Muniraju E, Sharadamma P,
Year of Recommendation : 1985
Salient Features of the Technology :

Muscardine disease occurs from about ten species of fungi.  Among these white, green and yellow muscardine diseases are important. Usually this disease occurs when humidity is high in the environment and less temperature (< 25C) in the rearing house.

Symptoms:

  • Digestion capacity of silkworm decreases when the infection increases.
  • In white muscardine affected larvae, oil specks on the integument are not clearly visible, round clearly visible oil specks are seen in green muscardine and black speck are seen in yellow muscardine.
  • After the death of silkworm, mycelia comes out on intersegmental region through spiracles and spread all over the body and develop spores except head.
  • The colour of the different muscardine spores can be manifested after infection of silkworm.

Control measures:

Dithane M-45 and China clay : To control muscardine disease, use Dithane M-45 and Rangoli powder/china clay mixture.  Rangoli powder or China clay should be thoroughly ground and sieved with high mesh size (250-300). Dithane M-45 and Rangoli powder/sudde mannu should be mixed in the following proportion :

 

Silkworm instar

Dithane M-45

Rangoli powder/ China clay

1st to 3rd instar

1 part

99 parts

4th to 5th instar

2 parts

98 parts

 

Mix Rangoli powder/China clay in equal proportion as mentioned above and the mixture is to be taken into a clean and thin muslin cloth and dust on the chawki worms uniformly.

Formalin chaff (Mixture of roasted paddy husk with formalin): Concentrations of formalin chaff for each instars of silkworm are given below:

 

Stages of Silkworms

Formalin : Water

Percentage

2nd instar

1 part : 89 parts

0.4

3rd instar

1 part : 71 parts

0.5

4th instar

1 part : 59 parts

0.6

5th instar

1 part : 44 parts

0.8

Paddy husk has to be roasted till it becomes dark. One part of formalin according to the concentration of each instar as mentioned above and 10 parts of roasted paddy husk are to be mixed thoroughly and as a result, the paddy husk absorbs the formalin and releases slowly when it is dusted on the silkworm larvae. When the formalin is mixed with paddy husk as such it would not absorb the formalin and leaves out very quickly besides due to sharp edges, the paddy husk may cause wound to silkworm.  Prepared mixture of formalin chaff has to be dusted on silkworm body uniformly and covered with paper after bed cleaning daily when the disease manifests.  Feed the larvae after 30 minutes of dusting.  As precautionary measures dust formalin chaff once in 2nd instars and once in two days for 3rd instars onwards when there is no disease.

Advantages over Alternative Technologies :

Precautions while Adoption/Usage :
  • Three days prior to conducting the silkworm rearings, the rearing house and appliances should be disinfected thoroughly with 3% formalin (1 part formalin and 1 part water) @ 1 litre of prepared solution for 1 mt floor area.  Doors and windows of rearing house should be kept open for 24 hours to remove all the traces of formalin.
  • If temperature of rearing house is less than 22C, use electric heaters/fired charcoal to increase the temperature in the rearing house.
  • Wash the blue eggs with 1% formalin (1 part formalin : 35 parts water) solution for 5 minutes, then wash with running water and shade dry.
  • Provide sufficient ventilation in the rearing house, by opening windows and doors.
  • Rearing bed should be kept thin during rainy season to avoid moisture content.
  • When the humidity is high in the rearing house, feed the silkworms with cut mulberry leaves even during 5th instars.
  • To prevent the contamination, collect the infected silkworm from the rearing bed, put in 2% formalin (1 part formalin: 17 parts water) solution, burnt outside the rearing house.
  • Rearing appliances should not be kept for a longer period in the crop contaminated rearing house.
  • Keep rotating the rearing trays after every feed in the rearing stand to provide equal aeration, light and temperature that will help in equal development of the larvae.
  • The diseased and dead larvae (chalk like) should be handled using forceps to avoid contamination.
Source of Information :

KSSRDI Handout, 1985.

Photo of technology

:
Mucardine infected larvae Muscardine infected larva