Lac Culture | Zoology Optional Notes for UPSC PDF Download

Introduction

Lac, a resinous exudation from the body of female scale insects, has been utilized in India since the Vedic period. References in the Atherva Veda and Mahabharata highlight its significance, even describing a "Laksha Griha," a lac-based house used for nefarious purposes. The term "lac" in English is synonymous with "Lakh" in Hindi, indicating a hundred thousand and deriving from the Sanskrit word "Laksh." This suggests that the ancient Vedic people were aware of the biological and commercial aspects of the lac industry.

Greeks and Romans also had knowledge of lac, with a history of cultivation dating back around 4000 years in China, coinciding with the development of the silk industry. Lac is a unique commercial resin of animal origin, produced by tiny lac insects. Its applications, including lac resin, dye, and wax, have evolved over time and continue to find uses in Ayurveda and Siddha systems of medicine.

In the present age, lac's significance is heightened due to its eco-friendly, biodegradable nature, and its role in ecosystem development. Cultivation of lac insects on host trees in wasteland areas contributes to both environmental sustainability and economic returns, particularly benefitting tribal and economically disadvantaged communities.

Lac Insect Taxonomy

The scientific understanding of lac insects began with J. Kerr's account in 1782, published in the Royal Society of London. Initially named Tachardia lacca, it was later changed to Laccifer lacca Kerr, also known as Kerria Lac Kerr.

• Phylum: Arthropoda
• Class: Insecta
• Order: Hemiptera
• Suborder: Homoptera
• Super family: Coccoidea
• Family: Lacciferidae
• Genus: Laccifer
• Species: lacca

Lac insects, belonging to the Coccoidea super family, encompass around 2000 scale insect species worldwide. Laccifer is the genus responsible for secreting commercial lac, with Laccifer lacca (Kerr) being the primary species in India.

Distribution

Due to their dependence on specific tropical trees, lac insects are primarily distributed in South-East Asian countries. India and Thailand are key producers globally, with India leading in lac production. Over 90% of Indian lac comes from states like Bihar, Jharkhand, West Bengal, Madhya Pradesh, Chattisgarh, Eastern Maharashtra, and northern Orissa. Lac cultivation has also expanded to areas like Andhra Pradesh, Punjab, Rajasthan, Mysore, Gujarat, and Mirzapur and Sonebhdra districts of Uttar Pradesh.

Life Cycle

The lac insect, a minute crawling scale insect, undergoes a six-month life cycle:

Nymph and adults of lac insects.

• Stages: Egg, nymph instars, pupa, and adult
• Reproduction: Ovoviviparous mode, with females laying 200-500 fully developed eggs
• Emergence: Crimson-red first instar nymphs (crawlers) emerge, swarming for about 5 weeks
• Settling: Nymphs settle on twigs, secreting resin that hardens into a protective covering
• Molting: Nymphs molt thrice before maturity, with the duration of each instar influenced by temperature, humidity, and host plant
  
• Adult Stage: Males undergo complete metamorphosis, developing wings for fertilization, while females become immobile, focusing on egg production
• Harvesting: Resin-encrusted branches are harvested after the completion of the life cycle, dried, and processed for various lac products. A portion of brood lac is retained for inoculation in new trees.

Photograph of lac encrusted twig.

Host Plants

Lac insects thrive on specific plant species, extracting plant sap and secreting lac resin. These plants, termed host plants, are not considered pests due to several reasons:

• Yielding Useful Product: Lac insects produce a valuable product.
• Economic Importance: Host plants are not economically vital.
• Temporary Damage: Insects cause recoverable damage to host plants.

Approximately 113 host plant varieties are recognized, with some common ones in India being:

1. Butea monosperma (Palas)
2. Zizyphus spp (Ber)
3. Schleichera oleosa (Kusum)
4. Acacia catechu (Khair)
5. Acacia arabica (Babul)
6. Acacia auriculiformis (Akashmani)
7. Zizyphus xylopyrus (Khatber)
8. Shorea talura (Sal - grown in Mysore)
9. Cajanus cajan (Pigeon-pea or Arhar)
10. Grewia teliaefolia (Dhaman - preferred in Assam)
11. Albizzia lebbek (Siris/Gulwang)
12. Flemingia macrophylla (Bholia)
13. Ficus benghalensis (Bargad)
14. Ficus religiosa (Peepal)

Major host plants include palas, kusum, ber, and khair, with kusumi lac considered superior based on industrial parameters, fetching higher market prices.

Strains of Lac Insect

In India, lac insects have two distinct strains: kusumi and rangeeni. The kusumi strain, grown on kusum or other host plants using kusumi brood, has two crops - Jethwi (June/July) and Aghani (Jan./Feb). Rangeeni strain, thriving on host plants other than kusum, has two crops - Karrtiki (Oct./Nov.) and Baisakhi (May/June). Aghani and Baisakhi of rangeeni strain contribute about 90% of lac production, while kusumi crops contribute the remaining 10%. Kusumi crop lac is preferred for its lighter color and higher market value.

Lac Cultivation

Lac cultivation involves placing brood lac on specific host plants, containing gravid females ready to lay eggs. The life cycle takes about six months, allowing for two crops a year.

Local Practice

• Lac cultivation is simple, requiring part-time attention.
• Disadvantages include continuous exploitation of host plants without rest, natural inoculation, and lack of pruning.
• Defective practices lead to weakened host plants and eventual abandonment of lac cultivation.

Improved Practice

• Improved lac cultivation requires proper rest for host plants, adopting a coupe system.
• Coupe system divides host plant trees into groups (coupes), allowing alternate groups to rest and recover.
• Improved practices include using superior breeds of lac insect, providing rest to host plants, using good-quality brood lac, post-harvest and pest management.

Propagation of Lac Insects

• Propagation involves inoculating newly hatched nymphs.
• Two types of inoculation: natural (self/auto-inoculation) and artificial.
• Natural inoculation weakens host plants; therefore, artificial inoculation is recommended.

Improving lac cultivation methods, involving forest dwellers in Joint Forest Management programs, and ensuring timely availability of quality brood lac are essential for sustained production and steady returns.

Natural Inoculation

• Drawbacks: Natural inoculation has limitations.
• Process: Nymphs infect the same host naturally, causing weak host plants.

Artificial Inoculation

• Purpose: Counter the drawbacks of natural inoculation.
• Pruning: Host plants pruned in Jan. or June, inducing the growth of new succulent twigs.
• Brood Twig Preparation: Brood twigs cut (20-30 cm), tied to fresh tree twigs.
• Precautions:
  • Use fully mature, pest-free brood.
  • Use brood immediately after crop cutting.
  • Securely tie brood lac on upper surface of branches.
  • Heat room if swarming is prevented by bad weather.
  • Avoid cultivating kusumi in rangeeni areas and vice versa.

Alternation of Brood and Host

• Purpose: Prevent deterioration in quality of brood lac.
• Recommendation: Change brood and host alternately for better quality.

Inoculation Period

• Strains: Kusumi and Rangeeni strains yield two crops each.
• Periods:
  • Kusumi Strain: Jethwi (Jan./Feb.), Aghani (June/July).
  • Rangeeni Strain: Kartiki (Oct./Nov.), Baisakhi (May/June).

Harvesting of Lac

• Immature Harvesting (ARI Lac):
  • Before swarming.
  • Recommended for Palas lac (Rangeeni lac).
• Mature Harvesting:
  • After swarming.
  • Yellow spot development indicates maturity.

Considerations for Harvesting

• Harvest only when mature.
• Mature crop defined by nymph emergence in 7-10 days.
• Reap the entire crop if self-inoculation is not required.
• Harvesting periods for different crops vary.

Harvesting Recommendations

• Harvest mature crops to avoid nymph damage.
• Harvest within 7-10 days before nymphal emergence.
• Utilize harvested brood sticks promptly or store in ventilated rooms.
• Harvesting at maturity reduces loss, enhances yield, and maintains quality.

Composition of Lac

• Main Constituent: Lac resin, a polyester complex.
• Other Constituents:
  • Lac wax (6%)
  • Lac dye (1-2%)
  • Others (25%): Includes dye, wax, sugar, proteins, soluble salts, sand, woody matter, insect body debris.

Lac Processing

Stick Lac

• Post-Harvest Processing: Removal of lac encrustations from host twigs by scraping.
• Quality Factors: Dependent on host tree, climate, harvesting time, drying method, and storage.
• Storage Recommendations: Stick lac prone to lump formation; optimum moisture content for storage is 4%.

Seed Lac

• Processing: Crushed and sieved to remove impurities.
• Washing: Washed in vats to break open insect bodies, remove lac dye and twig debris.
• Result: Semi-refined commercial variety called seed lac.
• Grades: Various grades based on color and impurity levels.

Shellac

• Processing Methods: Handmade, Heat, and Solvent.
• Grades:
  • Handmade Process:
    • Lemon one, Lemon two, Standard one, Superior, etc.
  • Heat Process:
    • Orange, Lemon one, Lemon two, Standard one, etc.
  • Solvent Process:
    • Dewaxed platina, Dewaxed blonde, Dewaxed super blonde, etc.

Bleached Shellac

• Bleaching Process: Dissolving seed lac in aqueous sodium carbonate solution, stirring with sodium hypochlorite, filtering, and reclaiming with sulfuric acid.
• Result: White in color, two grades - Dewaxed bleached shellac and Waxy bleached shellac.

Isolation of Aleuritic Acid

These comprehensive notes cover lac inoculation methods, harvesting, lac composition, and processing methods, providing a thorough understanding of lac cultivation and its industrial applications.

Lac Products And Their Use

Lac Dye

• Composition: Mixture of anthroquinoid derivatives.
• Traditionally Used For: Coloring wool and silk.
• Color Variation: Purple red, brown, and orange based on mordant used.
• Applications:
  • Food and beverages industry for coloring.
  • Increasing demand due to eco-friendly and safe material preference.

Lac Wax

• Composition: Mixture of higher alcohols, acids, and esters.
• Uses:
  • Polishes for shoes, floors, automobiles.
  • Food and confectionery industry.
  • Drug tablet finishing.
  • Lipsticks.
  • Crayons.

Shellac

• Composition: Natural gum resin with wax.
• Properties:
  • Hard, tough, amorphous, brittle resin.
  • Soluble in alcohols and organic acids.
  • Acidic (acid value 70), ester, hydroxyl groups.
  • Insoluble in water, glycerol, hydrocarbon solvents.
• Extraordinary Properties:
  • Thermoplastic, UV-resistant.
  • Excellent dielectric properties.
  • Powerful bonding material with low thermal conductivity.
• Uses:
  • Fruit coatings, glazing agents for sweets.
  • Binder for foodstuff stamp inks.
  • Cosmetic applications: mascara, nail varnish, hair spray.
  • Pharmaceutical coatings, wood treatment, textiles, electronics, and more.

Bleached Shellac

• Characteristics:
  • Non-toxic, physiologically harmless, and edible.
  • Properties: binding, adhesive, hardening, gloss, odorless.
• Applications:
  • Paints, aluminium industry, pharmaceuticals.
  • Confectionery, textiles, cosmetics, wood finishing.
  • Used in fire works, electronics, grinding wheels, rubber, leather.

Dewaxed Bleached Shellac

• Characteristics:
  • Harder, brighter, and completely free from wax.
• Uses:
  • Coating of fruits, vegetables, tablets, capsules.
  • Confectionery, aluminium foil, cosmetic industry.
  • Coating for wood, leather, rubber, and textiles.

Aleuritic Acid (Shellac Aleuritic Powder)

• Source: Obtained from shellac by saponification.
• Composition: 9, 10, 16-trihydroxypalmitic acid.
• Properties: White powder, moderately soluble in hot water, soluble in lower alcohols.
• Uses:
  • Perfumery: Synthesis of civetone, ambrettolide, isoambrettolide.
  • Medicine: Synthesis of Glucose monoaleuritate.
  • Plastics and Fibres: Preparation of lacquers, plastics, and fibers.

Lac Pests

Parasites

• Species: Small winged eight species of insect (Chalcidae, Order Hymenoptera).
• Behavior: Lay eggs in lac cells; grubs feed on lac insects within the cells.
• Damage: 5-10% loss due to parasitization.

Predators

a. Eublemma amabilis Moori (White Lac Moth):

• Order: Lepidoptera
• Behavior: Eggs laid on lac encrusted twigs; larvae feed on lac insects.
• Preferential Target: Trees

b. Holocerca pulverea Meyr (Black Lac Moth):

• Order: Lepidoptera
• Behavior: Eggs laid on stored lac; larvae feed on stored lac.
• Preferential Target: Stored Lac

c. Chrysopa spp. (Lac Wing Fly):

• Order: Diptera
• Behavior: Eggs laid on lac encrusted twigs; larvae feed on lac insects and encrustations.

Other Pests

• Rodents: Squirrels and monkeys cause damage by gnawing mature lac encrustations.
• Precautions:
  • Use only healthy, pest-free brood lac for inoculation.
  • Harvest the entire crop to avoid attracting pests.
  • Fumigate or immerse stick lac to kill pests.
  • Prompt scrapping of encrusted lac from twigs.
  • Destroy infected stick lac along with predators and pests.

Potential of India in Lac Production

Current Production

• India produces approximately 18,000 metric tonnes of unrefined raw lac annually.
• About 85% is exported to major lac importing countries such as the USA, Germany, and Egypt.

Potential for Lac Culture

• Classification of Areas:
  • Regular lac cultivation areas (20-25% utilization of available trees).
  • Moderate lac cultivation areas (10-15% utilization).
  • Untapped areas due to lack of knowledge and awareness.
• Current Utilization: Only 15% of available lac host trees are utilized for lac cultivation.

Indian Lac Research Institute (ICAR), Namkum, Ranchi

• Established in 1924, actively engaged in enhancing lac productivity.
• Developed various technologies and cultivation packages.
• Focus on scientific cultivation, host plant management, integrated pest management, and 'Joint Forest Management' program.

Challenges and Solutions

• Quality Issues: Untimely harvesting, inappropriate storage, and processing.
• Solutions: Adoption of recommended technologies developed by the Institute.

Conclusion

• Lac holds great potential in India due to its natural, renewable, and eco-friendly nature.
• Increased demand worldwide emphasizes the need for enhanced production.
• The untapped areas and improved cultivation practices can significantly boost lac production.
• The role of research institutes like ICAR in developing and disseminating technologies is crucial for the growth of the lac industry in India.