Unit 2: Economically Important Insects

1. Basic concept of artificial harvesting of honey (Apiculture)

Apiculture, or beekeeping, is the cultivation of bee colonies for the production of honey and other bee products. Artificial harvesting allows beekeepers to collect honey efficiently without destroying the colony.

Harvesting Process:

1. Removing Bees from Supers: The beekeeper first removes the bees from the "supers" (the boxes on top of the hive where honey is stored). This can be done using a bee escape (a one-way door placed 24 hours prior) or by brushing/blowing the bees off the frames.
2. Uncapping the Comb: The bees seal ripe honey in the honeycomb cells with a thin layer of white beeswax, known as "cappings". This must be removed. Beekeepers use a heated uncapping knife or an electric hot knife to slice off this wax layer.
3. Extraction (Centrifugal): The uncapped frames are placed inside a honey extractor. This machine spins the frames rapidly, using centrifugal force to throw the honey out of the combs and onto the walls of the extractor. This method keeps the wax comb intact, so it can be returned to the bees to be refilled, saving them enormous amounts of energy.
4. Filtering: The extracted honey flows to the bottom of the extractor and is drained. It is then filtered or strained through muslin cloth or sieves to remove any remaining wax cappings and debris.
5. Modern Alternatives (Flow Frames): A newer, more expensive method involves "Flow Frames," which are plastic honeycombs. By turning a key, the cells are offset, breaking the wax seal and allowing the honey to flow directly out of the hive into a collection vessel without removing the frames or disturbing the bees.

2. Culture of Silkworm for various types of silk production (Sericulture)

Sericulture, or silk farming, is the cultivation of silkworms to produce silk. The most common species is the domestic silkmoth, *Bombyx mori*, which feeds exclusively on mulberry leaves.

Process of Sericulture:

1. Rearing: Silkworms are fed mulberry leaves on trays. After their fourth molt, they are ready to spin their cocoons.
2. Spinning: The silkworm secretes a continuous filament of fibroin (a protein) from its salivary glands. This is cemented together by a gum called sericin. The worm spins this filament around itself, forming a protective cocoon to pupate in.
3. Harvesting & Stifling: The cocoons are harvested. In traditional sericulture, the cocoons are placed in hot water or steam. This process, called stifling, unfortunately kills the pupa inside. This is done to prevent the moth from emerging, as emerging would break the continuous silk filament into short, unusable pieces.
4. Degumming: The hot water from stifling also softens and removes the sericin gum, which frees the silk filaments for reeling.
5. Reeling & Throwing: The filaments from several cocoons (often 5-10) are located and unwound together as a single strand, a process called reeling. These single strands are then twisted together ("throwing") to create a strong, usable silk thread or yarn.

Types of Silk:

• Mulberry Silk: The most common type, from *Bombyx mori*. It is known for its softness and uniform white color.
• Wild Silk (Vanya Silk): Silks produced by wild silkworms, such as Tussar silk. These silkworms feed on a variety of plants, resulting in a less uniform, more robust, and typically golden-brown fabric.
• Ahimsa (Peace) Silk: In this method, the cocoons are harvested only *after* the moths are allowed to emerge and fly away, so no pupae are killed. However, because the moth breaks the cocoon, the filaments are short, resulting in a different texture (spun silk) than reeled silk.

3. Culture of lac insect for lac production (Lac Culture)

Lac culture is the rearing of tiny scale insects, primarily *Kerria lacca*, to produce a natural resin called lac. This resin is secreted by the female insect as a protective covering.

Process of Lac Culture:

1. Inoculation: A stick containing eggs ready to hatch (broodlac) is tied to the branch of a suitable host plant (e.g., Peepal, Ficus).
2. Crawling & Settlement: The eggs hatch into larvae called "crawlers." These tiny red insects move to new, tender branches, settle down, and begin to feed on the tree's sap.
3. Resin Secretion: As they feed, the crawlers (especially females) secrete a resinous substance that gradually covers their entire body, forming a hard encrustation. This is the "lac".
4. Harvesting: After about six months, the branches, now heavily coated with lac, are ready for harvest. These are cut from the tree and are known as sticklac.
5. Processing:
   • The sticklac is crushed and sieved to remove the insect bodies and plant debris. This first-stage product is called seedlac.
   • The seedlac is then further processed, traditionally by heat treatment (melting, filtering, and stretching into sheets) or by solvent extraction, to create the final, purified product: shellac.