CHSE Odisha Vocational Sericulture cheat sheet

Sericulture = rearing of silkworms for silk; moriculture = mulberry cultivation; the two together form the raw-material base of the silk industry.

Four commercial silks: mulberry (Bombyx mori), tasar (Antheraea mylitta, A. proylei, A. assamensis), eri (Samia ricini), muga (Antheraea assamensis, golden silk, Assam only).

Silk = fibroin filament core (about 75-80% of fibre mass) cemented by sericin gum (about 20-25%); degumming removes sericin.

Mulberry silk accounts for roughly 90%+ of world raw silk; India is the only country producing all four commercial silks.

Life cycle: egg (about 10 days) - larva with 5 instars (about 24-28 days) - pupa in cocoon (about 10-12 days) - moth (about 3-5 days).

One rearing = one crop; Indian crop calendar: pre-monsoon (Feb-Mar), monsoon (Jun-Jul), post-monsoon (Sep-Oct), late autumn/winter (Nov-Jan).

Bivoltine (2 generations/year, temperate, high quality) vs multivoltine (many generations, tropical, hardy, lower yield); crossbreeds combine both.

Chain: mulberry leaf - silkworm rearing - cocoon - reeling - raw silk - twisting/throwing - weaving - dyeing/finishing - garment.

Propagation: stem cuttings (most common, 15-20 cm with 3-4 buds) for commercial planting; grafting, layering and seed for breeding or difficult varieties.

Planting geometry: pit system 90x90x90 cm at 90x90 cm spacing; row system (paired rows) for mechanised gardens; 2-3 crops of leaf per year from irrigated gardens.

Pruning regimes: bottom pruning (Dec-Jan, after leaf fall) for low-hill irrigated gardens; top pruning for rainfed; leaf harvest by leaf-picking, shoot-rearing or whole-shoot harvest.

Manures and fertilizers per hectare per year (irrigated): FYM 20-30 t; N about 250-300 kg, P2O5 about 120 kg, K2O about 120 kg, split into 3-4 doses after each pruning.

Irrigation: drip at 8-10 L/plant/day in summer; flood irrigation at 10-15 day intervals; waterlogging causes root rot, so drainage is mandatory.

Weeding: 3-4 hand weedings per year, first within 30 days of pruning; mulching with FYM or straw suppresses weeds and conserves moisture.

Mulberry pests: thrips, jassids, mealybug, whitefly, Bihar hairy caterpillar, cutworm, termites; diseases: powdery mildew, leaf spot, root rot, mosaic.

Leaf quality: harvest 6-8 week old leaves, avoid over-mature yellow leaves and tender top leaves; transport in baskets to avoid fermentation and heat.

Rearing house: separate rearing and leaf-storage rooms, 3-tier bamboo/wooden racks, 0.5 sq m/100 larvae at late stage, good ventilation and fly-proofing.

Incubation: eggs at 24-26 C and 80-85% RH, complete darkness or continuous light avoided; chawki (young-age) rearing in a separate room under a wet cloth.

Doses per acre of mulberry: about 400-500 dfls (disease-free layings) per crop; 1 dfl requires about 20-25 kg leaf over the larval period.

Rearing methods: shelf rearing (most common), floor rearing, shoot rearing (saves labour, 2-3 times leaf capacity).

Temperature and RH: young age 26-28 C, 85-90% RH; late age 24-26 C, 65-75% RH; high humidity in late age causes flacherie and muscardine.

Feeding: 3-4 feeds/day in young age (chopped tender leaves), 4-5 feeds/day in late age (whole leaves); feed 20-30% of leaf in the first 3 instars and 70-80% in the last two.

Spinning: mature worms stop feeding and become translucent; mount on chandrika/rotary mountages at about 40-50 worms per mountage; harvest cocoons 5-7 days after mounting.

Leaf quality and quantity drive cocoon yield; avoid wet or fermented leaves, which cause flacherie and cocoon loss.

Pebrine (Nosema bombycis): transovarian transmission; symptoms are pepper-spot black spores, irregular growth, mottled larvae; control by mother-moth examination and dfl certification.

Flacherie: bacterial (Bacillus, Streptococcus, Serratia) and viral (BmNPV, infectious flacherie virus); symptoms are soft, flaccid, foul-smelling larvae; control by good ventilation and hygienic rearing.

Grasserie (BmNPV): nuclear polyhedrosis, larvae become swollen and milky, rupture to release polyhedra; spread by contaminated leaf and excreta.

Muscardine: Beauveria bassiana (white), Metarhizium anisopliae (green), Paecilomyces (yellow); larvae become hard and chalky; control by reducing humidity and dusting slaked lime.

Disinfection: 2% formalin or 1% bleaching powder for rearing house and appliances; 0.5% formaldehyde for eggs; sun-drying and washing of bamboo articles.

Pests of silkworm: ants, mites, lizards, rats, birds, and uzi fly (Exorista bombycis); uzi fly controlled by mesh screens, releasing the parasitoid Nesolynx thymus, and removing maggot-infested larvae.

Prevention: separate chawki and late-age rearing, one crop per season, 2-week gap between crops, proper disposal of bed refuse and dead larvae, footbaths at entry.

Bed cleaning: first cleaning after the first moult, then after each moult; remove excreta and dead worms to reduce disease load.

Cocoon storage: dry and cool, spread in thin layers, and reel within 3-5 days of harvest; sun-drying reduces quality.

Stifling: hot air or steam at about 80-90 C for 30-40 min to kill the pupa and prevent moth emergence; sun-drying is a cheap but inferior method.

Cocoon quality: shell weight, shell ratio (shell weight/cocoon weight x 100), filament length, reelability and neatness determine reeling value.

Reeling: cocoons are cooked in water at 90-95 C for 2-3 min, brushed, and reeled on a multi-end reeling machine or cottage basin; reeling speed and thread count set by denier.

Denier = weight in grams of 9,000 m of silk; mulberry raw silk is usually 20/22 denier, one denier = 1/9 tex.

Spinning: tasar, eri and muga cocoons are usually spun (not reeled) on charkha or spinning machines because their filaments are discontinuous.

Reeling waste: dupion, knub and noil are produced from imperfect cocoons; waste silk is spun into yarn for furnishing and khadi.

Post-cocoon care: avoid exposure to sunlight and moisture before stifling; wet cocoons rot and lose reelability.

Raw silk tests: denier, denier deviation, tenacity and elongation, cohesion, neatness, cleanliness, and winding performance.

Denier is measured by weighing a known length; denier = 9,000 x weight (g) / length (m); denier deviation is expressed as a percentage of the average.

Neatness: number of defects per 100 m or per 1,000 m; cleanliness: count of major and minor defects per 100 m; both are graded against standard photographs.

Tenacity of raw silk is about 3-4 g/denier; elongation at break is about 15-25%; silk loses strength when wet.

Silk grade is based on the combined test results; the International Silk Association grading is a common reference, with 6A as the highest grade.

Cocoon grading: shell ratio (good cocoons 18-22%), reelability (75-85%), filament length (800-1,200 m), and number of breaks during reeling.

Moisture regain of silk is about 11% at standard conditions (20 C, 65% RH); oven-dry weight is used to correct the conditioned weight.

Quality control: random sampling, standard laboratory conditions, calibrated instruments, and record of each lot for traceability.

Cost of production per crop = fixed costs (shed, racks, equipment depreciation) + variable costs (dfls, leaf, labour, disinfectants, mountages).

Gross income = cocoon yield (kg) x market price (Rs/kg); net income = gross income - total cost; benefit-cost ratio = gross income / total cost.

Cocoon yield benchmark: 40-50 kg per 100 dfls for multivoltine, 60-80 kg for bivoltine under good management; 1 kg cocoon needs about 20-25 kg leaf.

Marketing channels: regulated cocoon markets (cocoon price by open auction), reelers, private traders, and cooperative societies; price depends on breed, shell ratio and moisture.

Value addition: reeling, twisting, weaving, dyeing, and products such as silk sarees, stoles, and silk waste articles raise income per kg of cocoon.

Government support: Central Silk Board schemes, state sericulture department subsidies, and Silk Samagra for plantation, rearing and post-cocoon infrastructure.

Entrepreneurship: small-scale reeling unit, chawki rearing centre, cocoon trading, and silk weaving unit are common low-investment entry points.

Record keeping: crop-wise leaf, dfl, labour and cocoon data allow calculation of economics and identification of loss-making steps.

Rearing house preparation: clean, wash, sun-dry, then disinfect with 2% formalin or 1% bleaching powder; allow 2-3 days drying before brushing.

Chawki rearing: brush larvae on paper or paraffin sheets, feed chopped tender leaves, and cover with wet cloth/paraffin paper for the first 2-3 days.

Moult care: stop feeding when larvae settle for moult, keep the bed dry and undisturbed, and resume feeding after all larvae have moulted.

Mountage handling: shift mature larvae to chandrika at the right time, keep the room dark and ventilated, and harvest after 5-7 days.

Record formats: rearing register (date of brushing, dfl source, leaf fed, temperature/RH, mortality, cocoon yield) and mulberry garden register (pruning, manure, irrigation, leaf harvest).

Sampling and measurement: weigh 10-20 larvae or cocoons from random spots, not from the edge; use a calibrated balance and record the average.

Safety: handle formalin with gloves and in a ventilated area, and avoid skin contact with bleaching powder and pesticides.

Field visit: observe pruning, manuring, rearing, mounting and reeling steps; note the labour and material used at each step for the economics record.