Sericulture and Silkworm Rearing: Production and Biology
Sericulture: Definition and Economic Importance
Sericulture is the rearing of silkworms for the production of silk. It is a farm-based, labor-intensive, and commercially profitable agro-industry that provides employment and income to rural people, especially women and small farmers.
Main Scopes and Benefits of Sericulture
- Employment Generation: Provides year-round jobs to farmers, reelers, weavers, and traders.
- Rural Development: Boosts the rural economy through cottage industries.
- Export Potential: India earns valuable foreign exchange through the export of silk and silk goods.
- Agro-based Industry: Uses locally available resources such as land, mulberry, and labor.
- Eco-friendly: Sericulture is non-polluting and sustainable.
- Women Empowerment: Many women are engaged in rearing and reeling work.
History of Silk Production
The origin of sericulture dates back to China (around 2700 B.C.), discovered by Empress Si-Ling-Chi.
It later spread to India, Japan, and Korea through trade routes.
- In India, silk production has been practiced for over 2000 years.
- During ancient times, silk was a luxury material used by kings and nobles.
- After Independence (1947), the Central Silk Board (CSB) was established in 1948 to develop the industry scientifically.
Today, India is the second-largest silk producer in the world after China.
India produces all four commercial varieties of silk – Mulberry, Tasar, Eri, and Muga.
Conclusion: Sericulture in India has great scope for income, employment, and export.
Biology of the Silkworm (Bombyx mori)
Scientific Name and Classification
| Rank | Classification |
|---|---|
| Kingdom | Animalia |
| Phylum | Arthropoda |
| Class | Insecta |
| Order | Lepidoptera |
| Family | Bombycidae |
| Genus | Bombyx |
| Species | Bombyx mori |
Metamorphosis
The silkworm shows complete metamorphosis (Holometabolous type) with four distinct stages:
- Egg
- Larva (Caterpillar)
- Pupa (Cocoon)
- Adult (Moth)
Fecundity
A female moth lays 300–850 eggs after mating. Eggs are small, round, and light yellow. The eggs are used for rearing the next generation.
Incubation Period
The duration between egg laying and hatching takes about 8–10 days under normal temperature (25°C–28°C).
Larval Stages (Instars)
After hatching, larvae pass through 5 instars and 4 moults.
| Instar | Duration (days) | Features |
|---|---|---|
| 1st | 3 | Small, feeds on tender leaves |
| 2nd | 3 | Rapid growth |
| 3rd | 4 | Actively feeding |
| 4th | 4 | Larger and stronger |
| 5th | 6 | Maximum feeding; prepares to spin cocoon |
Pupation Period
The mature larva spins a cocoon around itself using silk thread secreted from its salivary glands. Inside the cocoon, it becomes a pupa.
Duration: 10–14 days, depending on temperature and humidity.
Adult Life Span
The adult moth emerges by breaking the cocoon. Adults do not feed; they only mate and lay eggs.
- Male life span: About 4–5 days.
- Female life span: 5–7 days.
Commercial Varieties of Silkworms
Silkworms are classified based on the host plant they feed on and the type of silk they produce.
| Type | Scientific Name | Host Plant | Type of Silk | Colour | Region |
|---|---|---|---|---|---|
| Mulberry | Bombyx mori | Mulberry (Morus alba) | Mulberry silk | White | South India |
| Tasar (Tussar) | Antheraea mylitta | Asan, Arjun trees | Tasar silk | Copper brown | Central India |
| Eri | Philosamia ricini | Castor, Kesseru | Eri silk | Dull white | North-East India |
| Muga | Antheraea assamensis | Som, Soalu trees | Muga silk | Golden yellow | Assam |
Example: Mulberry Silkworm
- Scientific Name: Bombyx mori
- Host Plant: Mulberry (Morus alba)
- Rearing: Domesticated species, completely dependent on humans.
- Cocoon: White or yellow in color, used for producing fine silk.
- Economic Importance: Produces the best quality silk used in textiles.
Site Selection for Mulberry Cultivation (Nursery)
Selection of a proper site is very important for successful mulberry cultivation and silkworm rearing.
Land Type
Land should be medium to heavy, fertile, and well-drained. Avoid sandy or waterlogged soils.
Soil Requirements
- pH: 6.2 – 7.0 (neutral).
- Rich in organic matter and nutrients.
- Deep soil with good water-holding capacity preferred.
Irrigation Facility
Mulberry needs regular watering. A reliable irrigation source (well, canal, borewell) should be available nearby.
Accessibility
The site should be easily reachable by road for transport of leaves and cocoons. Avoid areas too close to busy roads (dust may affect leaves).
Location
Avoid areas near forests (risk of wild animal damage). The site should be open, sunny, and free from water stagnation.
Climate
- Ideal Temperature: 20°C to 30°C.
- Requires moderate rainfall (600–900 mm/year).
- Should have good sunlight for healthy leaf growth.