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Government Of Assam Handloom Textiles & Sericulture Directorate of Sericulture

Silkworm Seed Technology

Disinfection and hygiene in seed production units

In order to ensure success full grain age operation, the grainage hall and the equipments should be disinfected properly. The disinfection operation can be categorized in to two stages (a) Washing and spraying (b) Fumigation

Washing and spraying

The grain age hall and its equipments at first should be washed thoroughly with clean water and/ or bleaching powder. After 24 hours they should be sprayed with 4% formaldehyde solution and should be kept air tight for 48 hours

(b) Fumigation

After 48 hours of formalin spray, 35 to 40 % commercial formaldehyde solution should be boiled inside the grain age hall keeping it air tight so that the vapours of the formalin effectively disinfect the room. After 48 hours the hall should be opened for proper aeration and should be washed with clean water. For production of dfls and have good crop one should consider the following steps.

Disinfection before grainage

  1. Grainage rooms along with the equipments should be disinfected and kept ready before the arrival of seed cocoons
  2. Seal the grainage hall 5-7 days prior to operation.
  3. Drench the walls and other bigger appliances with 5% bleaching powder solution.
  4. Dip smaller appliances in 5% bleaching powder solution.
  5. Use high grade bleaching powder with more than 30% chlorine content.
  6. Spray 2% formaldehyde solution and 0.5% slaked lime mixture @ 1 lit. per 2.5 sq.mtr. and leave the hall closed.
  7. Use disinfection mask, overcoat and hand gloves while disinfecting the grainage hall.
  8. Prepare fresh disinfectant by mixing 5 gm slaked lime in 1 litr. Of 2% formalin solution.
  9. As formalin is more effective a above 20°C, carry out disinfection preferably on sunny days.
  10. During high humid conditions the hall may be fumigated with 5% formaldehyde solution for 24 hours at least 3-4 days before and immediately after grainage operation.
  11. Complete the process of disinfection at least 3 days before consigning seed cocoons.


  1. Store seed cocoon in single layer in moth cages to avoid the rate od contamination Burn the dead and melted cocoons.
  2. Use hand glove, aprons and foot wears during grainages operation..
  3. Sprinkle bleaching powder and slaked lime mixture (100gm bleaching powder and 900 gm slake lime) at the entrance and around the grainage hall. @ 200 gm per sq.mtr.) 1-2 mtr. Around on alternate days.
  4. Disinfect the moth testing area regularly with 2% formalin and 5% bleaching powder solution.
  5. Dispose off the pierce cocoons as soon as possible.
  6. Dispose off crushed moths, papers etc. in soak pits after treating with 5% bleaching powder solution or burn them.
  7. Make soak pits always away from the grainage hall.
  8. Wash hand with alkaline soap and then 2% bleaching powder solution before entering the grainage hall.
  9. Disinfect footwear by steping on the mat soaked with 2% formaldehyde solution.

Price fixation for seed cocoons

The seed crop rearings and conducted during unfavourable seasons and hence the success of the seed crops is highly uncertain. However, once the cocoons are produced, they are sold to commercial rearers at very high price. Often the seed cocoon price depends on the place, demand and availability. The seed cocoons are sold in numbers of hundreds, thousand etc. and prevailing rates vary from rupees four hundred to five hundred per thousand seed cocoons. It is estimated that the current requirement of seed cocoons is about five crores to produce one crore commercial disease free layings (DFLs) as five seed cocoons are required for production of one DFL.


Fecundity maximum during September (168), followed by April (155), November (152), June (150) and August (149). Lowest fecundity during the month of February (133).

Egg size

Egg characters such as weight and size were found superior (0.0078g in weight and 2.8 mm in diameter) during June and inferior during February (0.0069 gm in weight and 2.0 mm in diameter).

Eggs transportation

  1. Eggs should not be exposed to direct sunlight. Incubation under fluctuating environmental conditions results in high morality of embryo or irregular hatching of larvae. The survived individuals later become susceptible to flacherie disease due to disturbed metabolic activity.
  2. Avoid stuffing the egg packets inside hand bags/poly bags etc.
  3. Transport dfls, individually in egg boxes.
  4. For bulk quantity, make boxes of muslin cloth or cotton mosquito net for appropriate size with capacity 50 dfls
  5. Fit individual bag in wooden frame and carry in plastic baskets during hot and dry weather.
  6. Do not place the egg basket near the engine of the vehicle during transportation.