Lac Production/Cultivation

Lac cultivation is the process of growing lac insects on specific host plants to harvest the resinous secretion known as lac. This natural resin has various industrial applications, including varnishes, polishes, and coatings. Here’s a detailed overview of the lac production process:

1. Process Overview:

Lac production involves inoculating brood lac on prepared host plants. The brood lac contains gravid (egg-carrying) female insects, which lay eggs. The newly hatched larvae settle on fresh twigs, suck the plant sap, and secrete a resinous coating, forming encrustations on the branches.

2. Cultivation Practices:

a) Local Practice:

• Continuous Exploitation: Host plants are continuously exploited without any resting period, leading to weakened plants.
• Natural Inoculation: Only natural inoculation occurs with partial harvesting. Some branches are left untouched for auto inoculation.
• Effects on Host Trees: Continuous use causes loss of vigour, making the plants weak and eventually leading to their death.

b) Improved Practice:

• Rest Period: Host plants are allowed to rest and recuperate after harvest.
• Division into Coupes: Trees are divided into groups (coupes), and only a few are inoculated at a time. This practice allows others to rest and regain vitality.
• Alternate Cultivation: Trees are used alternately for lac cultivation, ensuring better growth and sustainability.
• Kusumi Strain Practice: Requires 18 months of rest as it grows slowly. Trees are divided into 4 coupes, with each coupe inoculated once every two years. Resting coupes are pruned for new twig growth.
• Rangeeni Strain Practice: Trees are divided into 3 coupes (two large and one small) in a ratio of 3:1:3. Baisakhi crop is raised in two large coupes alternately every year, allowing 16 months of rest. Katki crop is raised in the small coupe every year, with an 8-month rest between crops.

3. Selection of Site: Choose areas with suitable climatic conditions and the availability of specific host plants like Kusum, Palas, and Ber. Proper selection ensures good growth and high resin yield.

4. Pruning: Pruning is done to stimulate the growth of fresh and succulent twigs, which are essential for larvae settlement. It also helps in the management of pest infestations.
5. Inoculation: Propagation of lac insects is done by transferring newly hatched nymphs to host plants. There are two types of inoculation:
6. a) Natural/Self/Auto Inoculation: Occurs when swarming nymphs infest the same plant again. Continuous natural inoculation on the same host leads to weak plants due to poor nutrition for nymphs. Results in an uneven sequence of inoculation.

b) Artificial Inoculation:

• Pruning: Old, weak, and diseased twigs are pruned in January or June to promote the growth of new twigs.
• Attachment of Brood Twigs:
  • Cut brood twigs (20 x 30 cm) containing live lac cells are tied to fresh twigs.
  • The twigs are tied securely to touch the tender branches at several points.
  • Nymphs migrate to the succulent twigs and begin the infestation process.
  • After swarming, the brood twigs are removed to prevent pest attacks.

Precautions for Artificial Inoculation:

• Use fully matured and healthy brood.
• Inoculation should be done immediately after cutting the brood lac.
• Securely tie brood sticks on the upper surface of branches.
• Maintain a room temperature of 20°C to induce swarming.
• Avoid cultivating Rangeeni in Kusumi areas and vice versa.
• Inoculate only on non-rainy days to ensure successful swarming.

6. Harvesting of Lac (Cropping):

Harvesting involves cutting the lac-encrusted twigs once the crop matures. It is classified into two types:

a) Immature Harvesting:

• Lac is collected before swarming, producing Ari Lac.
• This method may damage lac insects during harvest.
• Recommended only for Palas host plants.

b) Mature Harvesting:

• Lac is collected after swarming, producing Mature Lac.
• Symptoms of Swarming:
  • Yellow spots develop on the posterior side of the lac cell as the crop matures.
  • Encrustation appears dried out about two weeks before swarming.
  • Cracks appear on the encrustation before swarming.
• Harvesting can be done at any stage when the yellow spot covers one-third to half of the cell area.
• The leftover brood lac after the emergence of nymphs is known as Stick Lac or Phunki Lac.

7. Composition of Lac:

• Lac Resin: 68%
• Lac Wax: 6%
• Lac Dye: 1-2%
• Others: 25%

8. Types of Lac:

• Stick Lac: Obtained by scraping lac encrustations from the host plant twigs. Known as Crude/Scraped/Stick Lac. For storage, maintain 4% moisture content to avoid lump formation.
• Button Lac: Made by melting and solidifying lac into button-shaped cakes. Preferred for French Polishing and Floor Finishing. Contains wax, which may affect compatibility with other finishes like polyurethane.
• Seed Lac/Grain Lac: Produced by crushing, sieving, and washing stick lac in large vats. The bug bodies dissolve in water, producing Lac Dye as a byproduct. The remaining resin is dried, winnowed, and sieved to produce Seed Lac. Appears as yellow/reddish-brown grains of about 10 mesh size.
• Shellac: Processed from Seed Lac using any of the following methods: Handmade Country Process, Heat Process, Solvent Process Used as a natural resin in varnishes, polishes, and coatings.

9. Important Considerations:

• Ensure suitable host plant selection for different lac strains (Kusumi or Rangeeni).
• Proper pruning and rest periods for host plants are crucial for sustainable lac production.
• Follow appropriate inoculation and harvesting practices to maximize yield and maintain host plant health.
• Store lac products under optimal conditions to preserve quality.

10. Applications of Lac:

• Varnishes and Polishes: Used for wood finishing and surface coatings.
• Electrical Insulators: Shellac is a natural insulator.
• Food Glazing Agent: Used as a coating for confectionery.
• Cosmetics and Pharmaceuticals: Utilized in lipstick and tablet coatings.
• Textile Dye: Lac dye is a natural colorant for fabrics.