SERICULTURE

Rearing Techniques

Disinfect the rearing house and equipments to prevent silkworm disease, two-three days before rearing. First, wash the rearing house and the equipments with 2% bleaching powder. Then spray the room and equipments with 5% bleaching powder or 2% formaldehyde. Close the houses for 24 hours for the fumes to get diffused.

First incubate the dfls (egg card) at a temperature of 24-26ºC and RH 75-80%, one day prior to hatching (blue egg stage); cover the eggs with black paper (black boxing). Next day morning, open it and expose to diffused sunlight. As the larvae emerge out, fresh tender leaves collected from the plant are chopped into 0.5 x 0.5 mm size and sprinkled over the hatched larvae. After half an hour, transfer the larvae to the paraffin paper spread in the chawky trays (wooden trays) using fine brush. Provide wet foam strips around and prepare a compact bed. Give another feeding in the bed. Cover with paraffin paper and stack the trays one over the other on the stand. Up to 20 laying can be brushed in a tray of 90 x 60 cm.

Chawki rearing and cleaning

In a tray of 120 cm x 90 cm x 10 cm size, 20 DFLs are brushed and reared till the end of second age. From brushing to the end of second age, the larvae are fed with tender leaves. The leaves are selected from the largest glossy leaf, 3rd and 4th from the top for I instar larvae. The 5th to 8th leaves are used to rear the second instar larvae. In the first age, one cleaning is given just a day before the worms settle for moult. In the second age, two cleanings are given, one after resumption of feeding and the other
a day before the second moult.

Shoot rearing for late age worms

Provide separate rearing house for shoot rearing in shady areas. Fabricate the rack stand with wood or steel and the rearing seat with wire mesh/bamboo mat. Shoot rearing rack of 1.2m x 11m size is sufficient to rear 50 DFLs. Provide 15 cm border on all sides of the shelf to prevent the dispersal of the larvae. Arrange the shelves in three tier system with 50 cm space between the tiers Clean the bed once in each instar For cleaning, place two ropes parallelly on the bed and place the new shoots over the ropes. After all the worms have moved on to the new shoots, take the rope from the bed and remove the remains and refuses.

Shoot harvesting and feeding

Harvest the shoots at 1 m height from ground level at 60 to 70 days after pruning.
Store the shoots vertically upwards in dark cooler room. Provide thin layer of water (3 cm) in one corner of storage room and place the cut ends of shoots in the water for moisture retention. Provide a layer of newspaper in rearing shelf. Spread the shoot in perpendicular to width of the bed. Place top and bottom ends of the shoots alternatively to ensure equal mixing of different qualities of leaves. Transfer the third instar larvae to shoots immediately after moulting. Apply soyaflour twice @ 5g /kg of shoots on first day of first feeding during fourth and fifth instars.

Harvesting

Harvest the cocoons of crossbreeds and bivoltines on 5th and 7th day after spinning,
respectively.

Yield

Cross breeds : Rainfed 20-25 kg/100 DFLs, Irrigated 50-60 kg/100 DFLs
Bivoltines : 60-70 kg/100 DFLs

Last updated: 26-4-2007