Chapter 15 — Environmental and Applied Zoology
Key Concepts Quick Recap
| Applied Field | Activity | Organism Reared |
|---|
| Sericulture | Silk production | Silkworm (Bombyx mori) |
| Apiculture | Honey production | Honeybee (Apis mellifera, Apis cerana) |
| Pisciculture | Fish farming | Rohu, Catla, Grass carp, Tilapia |
| Poultry | Egg and meat production | Domestic fowl (Gallus domesticus) |
| Animal husbandry | Dairy, meat, draught | Cattle, buffaloes, goats, sheep |
| Lac culture | Lac production | Lac insect (Kerria lacca) |
| Prawn culture | Prawn farming | Penaeus monodon (tiger prawn) |
I. Choose the Best Answer (MCQs)
1. The silk-producing insect is: (a) Apis mellifera (b) Bombyx mori (c) Kerria lacca (d) Laccifer lacca
Answer(b) Bombyx mori Bombyx mori (mulberry silkworm) is the commercially important silk-producing insect. Larva (caterpillar) feeds on mulberry (Morus alba) leaves and spins a cocoon of raw silk. One cocoon produces 300-900 metres of continuous silk thread. Other silk-producing insects: Antheraea mylitta (Tasar silk, India), Antheraea assama (Muga silk, Assam), Attacus atlas (Eri silk).
2. Which honeybee species is most commonly used in commercial apiculture in India? (a) Apis florea (b) Apis dorsata (c) Apis mellifera (d) Apis indica (Apis cerana)
Answer(c) Apis mellifera Apis mellifera (European honeybee): most commonly reared for honey production worldwide due to high honey yield, docile nature, and suitability for modern box hive beekeeping. In India, Apis cerana indica (Indian honeybee) is also reared traditionally.
Honeybee castes:
- Queen: One per hive; only reproductive female; lays 1500-2000 eggs/day.
- Workers: Sterile females; gather nectar/pollen, make honey, defend hive.
- Drones: Males; mate with queen; die after mating.
3. Pisciculture is the rearing of: (a) Insects (b) Fish (c) Prawns (d) Frogs
Answer(b) Fish Pisciculture (fish farming): artificial cultivation of fish in tanks, ponds, or cages. Important species:
Benefits: controlled environment → higher yield; protein-rich food production; employment.
- Fresh water: Rohu (Labeo rohita), Catla (Catla catla), Mrigal, Grass carp, Common carp.
- Marine: Salmon, Tuna, Hilsa.
4. Jim Corbett National Park (India's first) was established in: (a) 1925 (b) 1936 (c) 1952 (d) 1972
Answer(b) 1936 Jim Corbett National Park (originally called Hailey National Park) in Uttarakhand: established 1936, India's first national park. Renamed after hunter-turned-conservationist Jim Corbett. Famous for Bengal Tiger. Project Tiger launched from here in 1973.
5. The IUCN Red List classifies species into categories. "Critically Endangered" means: (a) Extinct (b) Facing extremely high risk of extinction in the wild (c) Facing very high risk of extinction (d) Threatened
Answer(b) Facing extremely high risk of extinction in the wild IUCN Red List categories:
Examples: Snow leopard (VU), Bengal Tiger (EN), Great Indian Bustard (CR).
- EX: Extinct.
- EW: Extinct in Wild.
- CR: Critically Endangered (extremely high risk).
- EN: Endangered (very high risk).
- VU: Vulnerable (high risk).
- NT: Near Threatened.
- LC: Least Concern.
6. Vermiculture involves the use of earthworms to: (a) Produce silk (b) Decompose organic waste into compost (c) Control insect pests (d) Produce honey
Answer(b) Decompose organic waste into compost Vermiculture: using earthworms (typically Eisenia fetida — red wiggler) to convert organic waste (kitchen waste, crop residues) into vermicompost. Vermicompost is rich in nutrients (N, P, K), improves soil structure, and contains plant growth hormones. Eco-friendly alternative to chemical fertilisers.
7. Bioaccumulation of DDT in the food chain (biomagnification) leads to: (a) Thinner eggshells in birds → reproductive failure (b) Increased bird populations (c) Improved soil fertility (d) Increased fish populations
Answer(a) Thinner eggshells in birds → reproductive failure DDT biomagnifies along the food chain: plankton → fish → fish-eating birds. High DDT in birds inhibits calcium carbonate deposition in eggshells → thin, fragile shells → break during incubation → reproductive failure. Caused near extinction of raptors (eagles, peregrine falcon, ospreys) in 1950s-60s. DDT banned globally under Stockholm Convention (2004).
II. Short Answer Questions
Q1. Describe the process of sericulture.
Answer
Sericulture: rearing of silkworms for silk production.
Steps: 1. Egg stage (Layering): Female moth lays ~400-500 eggs on paper/cloth (preserved at 18°C). Eggs incubated → hatch in 10-14 days.
2. Larval stage (Rearing): Larvae (caterpillars/kambili puchi) fed fresh mulberry leaves (Morus alba). Larvae moult 4 times over ~28-30 days. Fifth instar larva = silk-spinning stage.
3. Cocoon spinning (Mounting): Mature larvae climb bamboo twigs → spin cocoon of raw silk (one continuous thread). Silk is the larva's salivary secretion (fibroin + sericin proteins). Cocoon spinning: 3-4 days.
4. Stifling: Cocoons heated (steam/hot air) → kills pupa inside → prevents moth from breaking silk thread when emerging.
5. Reeling: Cocoons softened in hot water → silk thread unreeled → spun into yarn.
6. Weaving: Silk yarn woven into fabric.
Economic importance:
- India = world's 2nd largest silk producer (after China).
- Karnataka is the leading silk-producing state.
- Employment for millions; important export.
Q2. What are the conservation measures for wildlife in India?
Answer
In-situ conservation (in natural habitat):
- National Parks: Strictly protected; no human activity. 106 in India.
- Jim Corbett (Bengal Tiger), Kaziranga (one-horned rhino, Assam), Periyar (elephants, Kerala).
- Wildlife Sanctuaries: Some human activity permitted. 567 in India.
- Biosphere Reserves: 18 in India; core (strictly protected) + buffer + transition zones.
- Nilgiri (first, 1986), Sundarban, Gulf of Mannar.
- Project Tiger (1973): Bengal tiger conservation; now 53 tiger reserves in India.
- Project Elephant (1992): Elephant conservation.
- Crocodile Conservation Project.
Ex-situ conservation (outside natural habitat):
- Zoological parks (Zoos): Breed endangered species in captivity.
- Gene banks: Preserve genetic material (gametes, embryos) of endangered species.
- Captive breeding programs: Kondana soft-furred rat, Red panda, Indian rhinoceros.
Legislation:
- Wildlife Protection Act, 1972: Prohibits hunting of scheduled species.
- Forest Conservation Act, 1980: Restricts diversion of forest land.
- CITES: Convention on International Trade in Endangered Species.
Common Mistakes
- Confusing Bombyx mori (mulberry silkworm — commercial silk) with lac insect Kerria lacca.
- Saying apiculture rears insects for silk — apiculture is for honey (bees); sericulture is for silk.
- Forgetting Jim Corbett is India's first national park (1936), not Kaziranga (1974).
- Confusing in-situ (in habitat: national parks) and ex-situ (outside habitat: zoos, gene banks).
Exam Checklist
- Sericulture: Bombyx mori (mulberry silkworm); India = 2nd largest silk producer; Karnataka = top state.
- Apiculture: Apis mellifera (commercial); castes: queen, workers, drones.
- Pisciculture: Rohu, Catla (freshwater fish farming).
- Jim Corbett NP: first in India (1936, Uttarakhand); Project Tiger launched here (1973).
- IUCN: EX → EW → CR → EN → VU → NT → LC.
- Biomagnification: DDT accumulates up food chain → thin eggshells in birds.
- Vermiculture: earthworms → vermicompost (organic waste decomposition).
- In-situ: national parks, sanctuaries, biosphere reserves; Ex-situ: zoos, gene banks.
