Applied Zoology: Pests, Diseases and Useful Animals
Applied zoology uses zoological knowledge for human benefit — from controlling vector-borne diseases to improving livestock through biotechnology.
An organism that transmits a pathogen from one host to another. Biological vectors harbour the pathogen during part of its life cycle (mosquito-malaria); mechanical vectors carry it externally (housefly).
Major insect vectors of human disease
| Vector | Disease(s) | Pathogen |
|---|---|---|
| Anopheles mosquito | Malaria | Plasmodium (P. falciparum, P. vivax, P. ovale, P. malariae) |
| Aedes aegypti mosquito | Dengue, yellow fever, Zika, chikungunya | Flaviviruses, alphavirus |
| Culex mosquito | Filariasis, JE, West Nile | Wuchereria, viruses |
| Sandfly (Phlebotomus) | Leishmaniasis | Leishmania spp. |
| Tsetse fly (Glossina) | Sleeping sickness | Trypanosoma |
| Reduviid bug | Chagas disease | Trypanosoma cruzi |
| Body louse | Typhus | Rickettsia |
| Flea (rat flea) | Plague | Yersinia pestis |
| Tick | Lyme, CCHF | Spirochaete, virus |
Malaria — the global burden
- 4 Plasmodium species infect humans; P. falciparum is the deadliest.
- Life cycle: female Anopheles mosquito (definitive host) + human (intermediate host).
- Pakistan: ~3 million cases annually (WHO estimate); Khyber Pakhtunkhwa and Balochistan are high-burden.
- Control: long-lasting insecticidal nets (LLINs), indoor residual spraying (IRS), prompt diagnosis (RDT), artemisinin-based combination therapy (ACT).
Dengue
- Aedes aegypti — bites by day; breeds in clean stagnant water.
- Pakistan: epidemic in Punjab (2011: ~21,000 cases in Lahore alone) and Sindh; recent surges in KP.
- Control: vector source reduction, public awareness campaigns.
Agricultural pests
| Pest | Crop damaged | Approx. damage |
|---|---|---|
| Locust (Schistocerca gregaria) | All field crops | 2019–20 outbreak in Pakistan was the worst in 25 years |
| Pink bollworm (Pectinophora gossypiella) | Cotton | Major resurgent threat since 2018 |
| Whitefly (Bemisia tabaci) | Cotton (CLCuV vector) | Severe yield losses |
| Fall armyworm (Spodoptera frugiperda) | Maize | Detected in Pakistan from 2019 |
| Red flour beetle | Stored grain | Storage losses |
| Rice stem borer | Rice | Yellow/white-ear damage |
| Sugarcane top borer | Sugarcane | Top kill |
Integrated Pest Management (IPM)
Combines cultural (rotation, sanitation), biological (predators like ladybirds, parasitoids like Trichogramma), mechanical (traps), and chemical (selective pesticides used judiciously) controls.
The FAO Locust Watch and Pakistan's Department of Plant Protection (Karachi) coordinate locust surveillance.
Useful animals
Honeybees (apiculture)
- Apis mellifera (imported) and Apis cerana (native Asian honeybee).
- Pakistan produces ~7,000 tonnes of honey/year; Sidr (Ziziphus) honey from KP is famous.
- Bees provide major pollination services worth billions globally.
Silkworm (sericulture)
- Bombyx mori feeds on mulberry leaves.
- Pakistan has potential in Punjab and AJK; output remains small.
Lac insect
- Kerria lacca produces shellac — historic industry in subcontinent.
Fisheries and aquaculture
- Marine fish — Pakistan EEZ landings ~400,000 t/year.
- Inland fisheries — Indus, lakes, reservoirs.
- Aquaculture — major species: Rohu (Labeo rohita), Catla (Catla catla), Mrigal (Cirrhinus mrigala), Tilapia.
- Shrimp export — Tiger shrimp (Penaeus monodon), white shrimp (Litopenaeus vannamei) farming.
Domesticated mammals
- Pakistani livestock detail covered in the Agriculture & Forestry module — Nili-Ravi buffalo, Sahiwal cattle, Beetal goat, etc.
- P. falciparum is the most lethal malaria parasite.
- Aedes aegypti is a day-biting dengue/Zika vector; Anopheles transmits malaria.
- The 2019–20 locust outbreak in Pakistan was the worst since 1993.
- Bt cotton combats bollworm; IPM is the modern paradigm.
- CRISPR and transgenic animals are emerging tools — e.g. disease-resistant mosquitoes.
Zoonoses
Diseases transmissible from animals to humans:
| Disease | Source animal | Pathogen |
|---|---|---|
| Rabies | Dogs, bats | Lyssavirus |
| Brucellosis | Cattle, goats | Brucella spp. |
| Anthrax | Cattle, sheep | Bacillus anthracis |
| Bovine tuberculosis | Cattle | Mycobacterium bovis |
| Avian influenza | Poultry, wild birds | Influenza A |
| Crimean-Congo HF | Livestock, ticks | Nairovirus |
| Toxoplasmosis | Cats | Toxoplasma gondii |
| Hydatid disease | Dogs | Echinococcus granulosus |
Crimean-Congo Haemorrhagic Fever (CCHF) is endemic in Pakistan — outbreaks linked to Eid-ul-Adha animal trade.
Animal biotechnology
- Embryo transfer, artificial insemination (mainstream in Pakistan dairy).
- In vitro fertilisation (IVF) for cattle.
- Cloning — Dolly the sheep (Wilmut, 1996).
- Transgenic livestock — disease-resistant or productivity-enhanced animals.
- CRISPR pigs/cattle — research stage globally; not yet commercial.
- Mosquito gene drives — under development against malaria.
For applied zoology, anchor your answers with named pests and diseases plus their vectors: P. falciparum / Anopheles, CLCuV / whitefly, locust / Schistocerca. Cite the 2019–20 locust outbreak and 2011 dengue epidemic in Lahore to ground the answer in Pakistani reality.
Wildlife trade and CITES
Trade in endangered species (live animals, parts, derivatives) is regulated by CITES (1973), with three appendices. Pakistan ratified in 1976. Markhor, snow leopard, houbara bustard and several reptiles/birds are listed.
The WWF-Pakistan TRAFFIC programme combats illegal trade in pangolin scales, freshwater turtles, snake skins and falcons.