New Update Production Technology of Mulberry silkworm
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Production Technology of Mulberry silkworm
Sericulture is an agrobased industry and it deals with mulberry culture and silkworm rearing. The rearing of silkworm involves the following steps 1. Preparation of rearing silkworm.
2. Collection of race.
3. Mating.
4. Sterilization of eggs.
5. Egg incubation.
6. Larvae rearing.
7. Ripening, spinning and cocoon formation.
8. Cocoon harvesting.
1. Preparation of rearing silkworm The rearing room and appliances used for rearing must be thoroughly cleaned and then disinfected with 24% formalin. Before disinfecting the rearing room, all crevices and holes should be filled.
2. Collection of race Selection of sericulture board recommended race of diseased free silkworm cocoon.
3. Mating Pairs adult just after emergence from cocoon by covering glass funnel and then remove male silkworm from female after mating. Immediately after copulation, female start to lay eggs. Provide egg card for egg laying. A female silkworm generally lays in an average 400 eggs (ranges 300-500).
4. Sterilization of eggs Collect and then sterilize the one day old eggs with 2% formalin for 5 minutes. Afterword, wash in running water.
5. Egg incubation
Leave the eggs at 22to 26 C temperature and 80to 85% relative humidity in an
incubator for incubation. In order to obtain uniform laying eggs at the blackhead stage are kept in black boxes on the day prior to hatching. In this way, the early maturing embryos are prevented from hatching and the late maturing embryo given time to develop and catch up with the early maturing ones. The next day, they are exposed certainly to diffused light so that the larvae has uniformly in response to the phototrophic stimulus. By this method, hatching of 90% and over can be obtained in one day.
Leave the eggs at 22to 26 C temperature and 80to 85% relative humidity in an
incubator for incubation. In order to obtain uniform laying eggs at the blackhead stage are kept in black boxes on the day prior to hatching. In this way, the early maturing embryos are prevented from hatching and the late maturing embryo given time to develop and catch up with the early maturing ones. The next day, they are exposed certainly to diffused light so that the larvae has uniformly in response to the phototrophic stimulus. By this method, hatching of 90% and over can be obtained in one day.
6. Larvae rearing
I) Brushing: The process of transferring the newly hatched silkworm to rearing trays is called brushing. During brushing, the cards with the newly hatched silkworm are placed in the rearing trays and mulberry leaves cut into smallsquare (0.5 cm2) are sprinkled over the egg cards. The hatched silkworm crawled on to the tender leaves and start feeding. Later the cards are removed and any worm still left on the cards are tapped on therearing tray.
I) Brushing: The process of transferring the newly hatched silkworm to rearing trays is called brushing. During brushing, the cards with the newly hatched silkworm are placed in the rearing trays and mulberry leaves cut into smallsquare (0.5 cm2) are sprinkled over the egg cards. The hatched silkworm crawled on to the tender leaves and start feeding. Later the cards are removed and any worm still left on the cards are tapped on therearing tray.
II) Feeding silkworm: Silkworms are feed to satisfy their apatite and to ensure their healthy and uniform growth. Care should be taken to feed the silkworm a sufficient quantity of high quality leaves. It is essential to supply chopped leaves to 1st and 2nd instar ones and whole leaves to the remaining instar. Usually four feeding a day at six hours interval in practiced. The quantity of the leaves required for rearing 50 laying or a box of 20,000 eggs at different instars is given below
Age/Instar Kg
1st 12
2nd 23
3rd 15-20
4th 35-50
5th 300-325
Total 353-400
III) Bed cleaning: Removing the old mulberry leaves, faeces matter of silkworm, any dead or unhealthy silkworm etc. from the rearing bed is called bed cleaning. Accumulation of any such matter creates environmental condition detrimental to the health of silkworm. Usually the bed is cleaned once during the 1st instar, twice during the 2nd instar. i.e. just after first mould and again before setting for second mould and three timesduring the 3rd instar. i.e. just after second mould in the middle of the age and again justbefore setting for next mould.
During 4th and 5th instar, the bed should be cleaned once a day in the morning. For cleaning purpose, usually nets are used. The net is spread over the bed and one
feeding is given before the nets are lifted and transferred to a fresh clean tray. The
worms crawl through the meshes in the net and come up to feed on the leaves on the
nets. If the worm are healthy, particularly all the worm will come up leaving the old
leaves litter behind on the old trays which are cleaned later. The mesh size of the net
used for the different instar are as follows
During 4th and 5th instar, the bed should be cleaned once a day in the morning. For cleaning purpose, usually nets are used. The net is spread over the bed and one
feeding is given before the nets are lifted and transferred to a fresh clean tray. The
worms crawl through the meshes in the net and come up to feed on the leaves on the
nets. If the worm are healthy, particularly all the worm will come up leaving the old
leaves litter behind on the old trays which are cleaned later. The mesh size of the net
used for the different instar are as follows
Age/Instar Mesh size
1st and 2nd 2 mm2
3rd 10 mm2
4th and 5th 20 mm2
IV) Spacing: Provision of adequate rearing seat space is of great importance of the
vigorous and full growth of silkworm. As the worm grow in weight and size. The
density in the rearing bed increases and condition of over crowding are faced. It is therefore, essential that the density of population in the rearing bed should be regulated.
The spacing to be provided for different ages of silkworm is given below
vigorous and full growth of silkworm. As the worm grow in weight and size. The
density in the rearing bed increases and condition of over crowding are faced. It is therefore, essential that the density of population in the rearing bed should be regulated.
The spacing to be provided for different ages of silkworm is given below
Age/Instar No of larvae/ft2
1st 3000-4000
2nd 2000-2500
3rd 1000-1200
4th 750-800
5th 150-200
Spinning 40-50
V) Environmental condition: Since silkworm have been reared in different
countries, they are influenced by nature wide delicate and very sensitive to
environmental condition. Among the various environmental factors that influence the
silkworm, the most important are
countries, they are influenced by nature wide delicate and very sensitive to
environmental condition. Among the various environmental factors that influence the
silkworm, the most important are
♦ Temperature.
♦ Humidity.
♦ Photoperiod.
♦ Air.
Temperature and humidity: The temperature and humidity requirement for
different instars are given below
different instars are given below
Age/Instar Temperature0 C RH (%)
1st 26-28 85
2nd 26-28 85
3rd 24-26 80
4th 24-25 75
5th 23-24 70
Spinning 25-26 60-70
Photoperiod: The usual photoperiod for silkworm larvae is 12 hours. However, the
light should not be too bright.
Air: Silkworm required fresh air for their various physiological functions. So proper ventilation should be provided.
light should not be too bright.
Air: Silkworm required fresh air for their various physiological functions. So proper ventilation should be provided.
7. Ripening, spinning and cocoon formation
When the 5th instar larvae reach the maturity, it can be understand by showing their translucent body colour and raising their head upwards. Maturity occurs within
6to 7 days after the last mould and in this time they completely cease feeding. Pick the larvae in time and place them in chandrika to facilitate undisturbed spinning cocoon
formation.
6to 7 days after the last mould and in this time they completely cease feeding. Pick the larvae in time and place them in chandrika to facilitate undisturbed spinning cocoon
formation.
8. Cocoon harvesting
Spinning taxes about 34 days and cocoon needs to be harvested after full 5 days. 5 days are enough to transform a larvae to pupa formation and also cocoon gets dry enough to stand well against the risk of being crushed during transport. Therefore, the cocoon should be harvested
after 56 days and then dry immediately in oven at 70-80 C for 24 hours or in the sun.
after 56 days and then dry immediately in oven at 70-80 C for 24 hours or in the sun.
Disease and Pest of silkworm
Disease Insect pest Pebrine: Nosema bombycis (Protozoan). Uzi Fly: Exorista bobmycis. Muscardine: Beauveria bassiana (Fungal). Dermestid beetles: Dermestes spp. Flacherie: Bacillus bombysepticus (Bacterial). Earwigs: Euborellia annulipes. Grasseric: Virus. Mites.
Gattine: Virus. Lizards, Rats, Squirrels, Birds etc.
Pebrine Disease
Symptoms
Egg stage
• Poor egg number.
• Reduction in size and weight. • Lack of adherence of substratum, disuniform with more of dead and unfertilized eggs.
• Irregular hatching.
Larval stage • Loss of appetite, retarded growth and disuniformity in size. • Irregular moulting. • Heavy mortality after 2nd moult if infected at egg stage. • Larvae shrink in size and vomit gut juice. • Dark brown or black spots may be seen sometimes on the body.
Pupal stage
• Pupa looks floppy and swollen.
• Irregular black spots on the body.
• Heavy mortality at pupal stage.
Moth stage
• Improper development of moth. • Deformed wings and distorted antennae. • Poor mating and egg laying. • Scale of wings and abdominal area come off easily.
Control Measures ♦ Pebrine disease can be controlled by disinfecting the rearing room, equipments and
rearing surroundings with 2% formalin. ♦During rearing, unequal size worms and faecal matter should be microscopically
examined for the presence of pebrine spores and if observed, larvae, cocoons and laying should be collected and burnt or buried. ♦In the grainages, scientific methods of mother moth examination should be employed♦ Surface sterilization of the eggs with 2% formalin for 5 minutes.
rearing surroundings with 2% formalin. ♦During rearing, unequal size worms and faecal matter should be microscopically
examined for the presence of pebrine spores and if observed, larvae, cocoons and laying should be collected and burnt or buried. ♦In the grainages, scientific methods of mother moth examination should be employed♦ Surface sterilization of the eggs with 2% formalin for 5 minutes.
Flacherie disease Flacherie disease of silkworm is caused by bacteria or virus individually or in
association. Depending on symptoms and cause they are called as bacterial flacherie disease,
septicemia, sotto disease, etc. The disease may occur due to fluctuations in temperature, humidity and feeding poor quality mulberry leaves.
association. Depending on symptoms and cause they are called as bacterial flacherie disease,
septicemia, sotto disease, etc. The disease may occur due to fluctuations in temperature, humidity and feeding poor quality mulberry leaves.
Symptoms
• Larvae become sluggish and loose appetite. • Body shrinks, becomes soft and flaccid. • Growth is retarded, becomes dull and vomits gut juice. • Loose clasping power of prolegs. • Body ferments, turn to different colour and oozes out foul smell.
Control measures
♦ Raise only healthy and strong silkworm races. ♦ Maintain proper temperature
(22-25°C) and humidity (80-85%) during incubation of eggs. ♦ Attend thorough disinfection of rearing room, appliances and surroundings.
(22-25°C) and humidity (80-85%) during incubation of eggs. ♦ Attend thorough disinfection of rearing room, appliances and surroundings.
♦ Take strict hygienic measures during rearing. ♦ Isolate infected larvae from the healthy one immediately and destroy by burning or dumping deep in the soil. ♦ Provide quality leaves for feeding and maintain proper spacing and ventilation.
♦ Maintain proper temperature and humidity during rearing. ♦ Destroy sluggish, irregular moulters and diseased worms. ♦ Do not allow late stage worms to feed on tender succulent leaves. ♦ Avoid injury to the worms, overcrowding of trays. ♦ Apply antibiotics like Streptomycin/Tetracyclin.
Grasserie disease Grasserie is a viral disease in silkworm caused by Nuclear Polyhedrosis (NPV),
Cytoplasmic polyhedrosis (CPV) and infectious flacherie. Nuclear polyhedrosis (NPV) is a major viral disease in silkworm. It is caused due to the presence of high temperature, high humidity and feeding of poor quality mulberry leaves. It is highly infectious.
Cytoplasmic polyhedrosis (CPV) and infectious flacherie. Nuclear polyhedrosis (NPV) is a major viral disease in silkworm. It is caused due to the presence of high temperature, high humidity and feeding of poor quality mulberry leaves. It is highly infectious.
Symptoms
In the early larval stage of infection, it is difficult to detect the disease. Microscopic examination of larvae may indicate the presence of polyhedral bodies. As the disease advances, the larvae loose appetite and skin becomes shiny before moulting. The intersegment membrane becomes swollen. The haemolymph or body fluid becomes turbid white. Microscopic examination shows presence of large number of polyhedral bodies.
Control measures
♦ Rear the larvae under clean and hygienic condition. ♦ Through disinfection of rearing room, appliances and surroundings. ♦ Ensure proper disinfection of egg surface. ♦ Incubate eggs under hygienic conditions. Avoid touching with hands. ♦ Provide suitable and timely feed during rearing. ♦ Maintain proper spacing and adequate ventilation. ♦ Pick out diseased, weak and injured larvae and destroy them properly. ♦ Apply bed disinfectants as per recommended schedule and quantity.
