Plant Protection: Entomology, Plant Pathology and Integrated Pest Management
What this domain covers
This domain tests insect structure and mouthparts, major pests and diseases, the disease triangle, IPM principles, economic threshold level and safe pesticide use.
Core rules and concepts
- Insect body: head, thorax and abdomen, three pairs of legs and usually two pairs of wings. Chewing mouthparts (caterpillars, grasshoppers) and sucking mouthparts (aphids, hoppers, bugs) demand different control measures.
- Metamorphosis is complete (egg-larva-pupa-adult) or incomplete (egg-nymph-adult).
- Major pests: rice stem borer, gall midge, brown plant hopper, leaf folder; mustard aphid; jute stem weevil; tea mosquito bug; fruit fly; termites.
- The disease triangle requires a susceptible host, a virulent pathogen and a favourable environment. Pathogens include fungi (blast, sheath blight), bacteria (bacterial leaf blight, citrus canker), viruses (tungro, banana bunchy top) and nematodes.
- IPM combines cultural, mechanical, biological, chemical and legal methods. Chemicals are used only when pest numbers cross the economic threshold level.
- Pesticide safety: read the label, wear protective clothing, respect the waiting period before harvest, avoid spraying in rain or at peak flowering and dispose of containers safely.
Worked example
Mustard shows curling shoots with dense aphid colonies. Aphids have sucking mouthparts inserted into plant tissue, so a contact insecticide that only wets the surface gives poor control. The reasoned choice is a systemic insecticide, or, under IPM, conserving ladybird predators and spraying neem-based formulation. Virus diseases such as tungro or bunchy top cannot be cured by insecticide; the vector is controlled and infected plants are removed.
Traps that cost marks
- Recommending insecticide to cure a virus disease.
- Mixing insecticides with alkaline materials, which destroys the active ingredient.
- Spraying before the economic threshold level and killing natural enemies.
- Ignoring the waiting period, so residue exceeds the permissible limit.