9 chapter silkworm rearing plan , rearing house plan and equipments

silkworm rearing plan , rearing house plan and equipments

1. Chapter - 9 SILKWORM REARING PLAN, REARING HOUSE PLAN AND REARING APPLIANCES, By, Nayana , B. P. Msc . (Agri.) SRF UAHS, Shivamogga

2. The rearing of the mulberry silkworms is fully domesticated . A silkworm-rearing house is the place where the silkworms are reared to produce cocoons. The cocoon quality and yield are adversely affected if the optimal environmental conditions i.e. temperature, relative humidity, ventilation, illumination, hygiene, etc . are not provided to the silkworms. The rearing house should be rationally designed in order to keep the micro-climatic and environmental conditions for rapid and healthy growth of the silkworms. It should, therefore , have facilities for creation and maintenance of the optimal environmental conditions inside the silkworm-rearing house. The rearing house should also provide sufficient space and healthy environment for the workers attending the silkworm rearing.

3. Optimal Environmental Conditions for Silkworms The optimum rearing temperature and relative humidity for different stages of the silkworms are as follows :

4. When the temperature and relative humidity inside the rearing house are below optimum conditions, they are artificially raised through charcoal or electric heaters and running humidifiers. When the rearing room temperature and relative humidity are above the optimum conditions, arrangements for natural cooling through good ventilation or forced cooling through wet curtains on windows, air coolers or air conditioner should be made besides covering the roof with mats made up of coconut fronds, grass etc.

5. LIGHT OR ILLUMINATION Young Silkworms prefer dark or dim light [15-30 lux]. Light intensity influences the even distribution of the larvae in the rearing bed. Silkworms are crowded in dark place in the rearing bed. VENTILATION A silkworm rearing house should be well ventilated. Poor ventilation leads to humidity built up and accumulation of gases like carbon monoxide, carbon dioxide , ammonia, etc., which adversely affect the growth of silkworms and make them susceptible to diseases

6. Rearing Bed Area Requirement for Silkworms The rearing bed area required for different races of the silkworms during different stages of growth is given below for 100 Dfls (2 Boxes) resulting in approximately 40,000 larvae . Rearing bed area required for silkworms during different stages for 40000 larvae

7. Young Age Silkworm Rearing House The Young age silkworm rearing houses are often called as Chawki Rearing Centre (CRC). Adequate care in terms of temperature, relative humidity and hygienic conditions should be provided to young silkworms for their good and healthy growth. A CRC for brushing 5000-6000 dfls per batch consists of a rearing hall of 30' x 30', leaf storage room of 10 ' x 20‘ and ante-room of 10' x 10' size. Adequate ventilation in the rearing hall is recommended. A continuous water channel inside the rearing hall along the walls helps in keeping the ants away from silkworms and also maintaining the humidity.

8. The windows should be fitted with wire mesh to avoid entry of uzi fly. The ceiling should be kept at 9'-10' from floor. In case of more roof height a false ceiling at 8' to 9' from floor helps in reducing the volume of air in the rearing hall so that required temperature and humidity can be maintained conveniently.

9. Late Age Silkworm Rearing House The silkworm rearing house should be located on an elevated place to avoid moisture migration from floor to rearing house, provide good cross ventilation , facilitate drainage of the water at the time of cleaning and disinfection. The rearing house should be north facing i.e., the windows face north and south. This will avoid direct entry of the sunlight into the rearing house. Ventilators should be provided above and below the windows for air circulation inside the rearing house. The rearing house should have cement flooring for maintaining hygiene.

10. A 10-15 cm deep channel inside all around the rearing hall should be provided to prevent entry of ants in the rearing area and also to drain out water at the time of cleaning and disinfection. During summer, the water in channel helps in increasing the humidity and cooling the air entering in through the lower ventilators. The roof of the house should be of either Asbestos sheets or RCC to avoid entry of the Uzi-fly. In hot regions, coconut fronds or straw should be placed over the roof to avoid heat radiations during day time. A false ceiling of plywood or thermocol sheet is also effective in reducing the solar radiation from roof.

11. The minimum width of a rearing house for late age rearing should be 5.5 m (18'). The length of the rearing house can be calculated as follows:

12. Late Age Silkworm Rearing House

13. The wall height in a rearing house should be minimum 10' on the sides and 14' at the center. An ante-room should be provided for washing hands and disinfecting legs before entering into the rearing area. Doors and windows should be fitted with wire mesh to avoid entry of uzi -fly into the rearing house. Water facility should be provided in a rearing house for cleaning/washing and disinfection and also for humidification purpose. The rearing house should have adequate lighting arrangements for working during night.

14. Electrical points in the rearing house should be provided for using heaters, humidifiers, coolers and lighting the building for workers during night hours. Provisions must be made for exhaust fans for evacuating humidity from rearing house during rainy days. Arrangements should be made to ward off rats, lizards, etc. and avoid entry into the rearing house. Shade trees around the rearing house should be planted to protect the walls and the roof from afternoon sun

15. REARING HOUSE The size of the rearing house depends on the size of mulberry garden, leaf yield and the number of eggs to be reared each time. While constructing the rearing house the following points are to be considered . The land selected should be sunny, airy, dry and as far as possible elevated and leveled. In temperate and subtropical regions the rearing house should be constructed in north - south directions . In tropical regions, however the building should be in east- west directions with doors facing north and windows facing north – south.

16. The building should be about 9-10 feet height and each room should be more than 12-15 feet wide. The building should be rat proof. The building should have broad verandha at least 6-8 feet wide on all the sides. Sufficient number of windows should be provided to admit free passage of air. The rearing house should have sufficient number of rooms for storing leaves, chawki and late age silkworm rearing and for mounting the spinning larvae . It should be possible to make it air tight for through disinfection.

17. The rearing room should be constructed in such a way that it should allow the rearer to plan either for shoot feeding or shelf rearing methodology. Raising evergreen trees like Cherry, Pongamia , Jackfruit, Neem or Mulberry trees around rearing house helps to maintain better rearing environment. For late age silkworm rearing, under shoot feeding methodology, the dimension of the rearing room should be 30’ X 15’ and such two rooms are required to rear the worms out of 400 disease free layings . There must be provision for separate rooms for chawki rearing and mounting of spinning worms

18. A rearing house planned for rearing capacity of about 300-400 layings should have the following accommodation under shelf rearing method. 1. Chawki rearing (one room) - 08' x 12' 2. Leaf storage (one room) - 15' x 12' 3. Late age rearing (One room) - 15' x 12' 4. Mounting of worms (One room) - 12' x 12'

19. Rearing stands : These are the frames used for holding the rearing trays and are placed in vertical rows. It is made of iron or wood or bamboo. The standard size is 2.5 m H. x 1.5 m L x 0.65 – 1.0 m W . It has 10-12 cross bars with a distance of 0.15m to accommodate 10-12 rearing trays. The size mainly depends upon the size of the trays. SILKWORM REARING EQUIPMENTS The following are the rearing appliances required for silkworm rearing in shelf rearing methodology.

20. Rearing trays : These are the portable receptacles used for keeping the worms during rearing and are placed one above the other in the rearing stand. They vary in shape and size. They are made up of either wood or bamboo or plastic.

21. Rectangular wooden trays : These are made of lighter wood. The commonly used trays measure 3.5' x 2.5'. For chawki (young age) rearing the trays measuring 1.2x 0.9 x 0.12m are used.

22. Circular bamboo trays : These are made of bamboo mat and the diameter of the trays is generally 3.5 ’ to 4 ’ . Bamboo trays are more popular than wooden trays as they are cheap, light and easy for handling. These are mainly used for rearing grown up worms as they facilitate good aeration.

23. Ant wells : The standard ant wells are concrete or stone block of 20 cm square and 5-8 cm height with a groove of 4cm running all around the top as receptacle for water. They are placed below the legs of the rearing stand and are filled with water to prevent ants from crawling up the stand and harming the silkworms. Paraffin or wax coated paper : It is a thick craft paper coated with paraffin wax and has the melting point of 55 C. It is used to cover the rearing beds during chawki rearing so as to prevent evaporation of moisture and to maintain high humidity in the bed.

24. Foam rubber strips : They are long foam rubber strips of 2.5 cm width and 2.5cm thick. They are dipped in water and kept all around the rearing beds in the tray during incubation and chawki rearing to maintain high relative humidity in the bed. Feather: Bird feather, preferably white ones are used for brushing newly hatched larvae from egg card to the rearing trays. It can also be used for shaping silkworm bed ad at the time of bed cleaning.

25. Chopping board: It is a rectangular board of soft wood used for cutting mulberry leaves. The dimension of chopping board 3ft x 3ft with a thickness of 5cms. Chopping knives: Knives with upward bent; 4-8 cm broad and 0.3 to 0.5 m long sharp blade with wooden handle are used for chopping mulberry leaves.

26. Mats: The mats are placed below the chopping board prior to chopping and used to collect the cut leaves without soiling. Feeding basins: They are used for holding chopped leaves while feeding to the worms.

27. Leaf preserving chamber: A chamber, the sides and bottom of which are made of strips of wooden reapers and is used to store harvested mulberry leaf. Wet gunny cloth is placed as a lining on all sides and top and sprinkled with water periodically to keep the leaves fresh. Bed cleaning nets: They are made of cotton or nylon thread and used for cleaning the rearing beds. The net mesh size of net is 2mm x 2mm for I and II instar , 10mm x 10mm for III instar and 20mm x 20mm for IV and V instar worms, and for each tray two nets are required.

28. Washbasin stand: It is used to hold a basin containing 2% formalin solution for disinfecting the hands before handling the silkworms. Foot cleaning tray: A pad made of gunny cloth soaked in 2% formalin solution and kept in a tray. It is placed at the entrance of the rearing room for disinfection of the feet of the persons entering the rearing house.

29. Room heaters: They are used to increase the temperature of the rearing room, whenever it falls below normal. Maximum and Minimum thermometer: It is used to record the maximum and minimum temperature of the rearing room. Dry and wet Bulb thermometer: It is useful in recording the room temperature and humidity during the rearing period

30. Hygrometer: It is also used to record the relative humidity of the rearing room. Chandrikes : They are also called as mountages or cocoonages . These are rectangular bamboo mat having bamboo sticks at all the edges. The bamboo tape is fixed on the mat at one side in spiral form at a distance of 4-5 cm. The ripe worms spin the cocoons between the two spirals.

31. Appliances used to support the spinning larvae Mountages - These are contrivances used for supporting the larvae when they spin the cocoons. Different types of mountages are used in different parts of India. In addition to support the spinning worms, the mountages should satisfy the following requirements . Provide convenient space of suitable dimension for spinning good sized cocoons . Should not promote formation of double cocoons, malformed cocoons and flimsy cocoons. Should have provisions for drying up of the last excreta of the worm prior to spinning and prevention of its falling on the cocoons of other worms.

32. The common mountages used in India are: Dried grass and twigs spread in shallow bamboo baskets are used in Assam. Dried weeds, paddy straw and fresh weeds are used in Jammu and Kashmir. In these two mounting and harvesting is difficult and require more labour . Further, formation of double and deformed cocoons is high. Should be suitable for easy mounting and harvesting. Should be cheap, durable, easy to handle, available easily, occupy less space, allow free flow of air.

33. c) Chandrika which is formed by a bamboo spiral is the most common mountage used in South India and West Bengal. This consist of a bamboo mat of size 1.8 m x 1.2 m supported by split bamboo reapers on all sides. On this bamboo mat, a bamboo tape of 4 to 5 cm width is wound in a spiral manner. The bamboo tape has V-shaped poles supported by three long bamboo strips. About 1000 worms can be mounted on this mountage .

34. The defects of this mountage are: percentage of flimsy and soiled cocoons are high. ii. drying is uneven. iii. harvesting and cleaning is difficult. Other recently introduced modifications under trial are screen type of bamboo mountage and plastic collapsible mountage . These are convenient to handle and store.

35. d) Bottle brush mountage It is introduced recently is not only cheap but can be fabricated very quickly and occupies very little space compared to Chandrika . It consists of a thick coconut or jute fibre -rope into which 6 to 9" sticks (midrib of coconut leaves) are inserted very closely. The silkworms used the sticks as support and spin the cocoons in the space between the sticks.

36. Rotary mountage : This automatic free-mounting mountage saves labour and reduces damage during handpicking. It consists of a frame with 10-12 boards. Each board is composed of 12 sections with 13 rows, making a total of 156 chambers open at both the ends. Ten such frames are assembled on a turning wooden frame.

37. Rotary mountage The mountages are kept above the rearing beds and revolve at a low speed and ripe worms from the bed crawl and select a chamber to spin the cocoon. Double cocoon formation is less. They are excellent cocoonages which encourage the spinning of quality cocoons and save expenditure on labour .

38. Rocker sprayer: It is used for spraying the disinfectants in the room and also to spray the water to the leaf storage chamber. Chawki rearing stand: The stand of 1 feet height used to keep the chawki rearing trays. Humidifier: It is used to maintain the relative humidity in the rearing room. Leaf carrying basket : It is a bamboo basket with narrow mouth and wide bottom. Basket is covered with wet gunny cloth and used to carry the mulberry leaves

39. Chop Sticks: These are two thin sticks of bamboo (17.5 to 20.0 cm) and are tapering at one end. At the thicker end they are connected by a small piece of thread and these sticks are used like a forceps for picking diseased worms and also the same can be used for shaping the bed after bed cleaning. Feeding stands: These are foldable stands (3’ height) on which the rearing trays can be rested at the time of feeding and bed cleaning to increase the labour efficiency.

40. Shoot rearing stand: The stands are used to rear the late age worms under shoot feeding methodology.

41. Thank you