Pest Management & IPM

EIL (Economic Injury Level) is the lowest pest population that causes economic damage equal to the cost of control — it is the point at which crop loss = management cost. ETL (Economic Threshold Level) or Action Threshold is set slightly below EIL (usually 75–80% of EIL) — it is the pest density at which control measures should be initiated to prevent the population from reaching EIL. ETL is the decision trigger; EIL is the damage threshold. IBPS AFO frequently tests both definitions and asks which is higher.

IPM integrates six types of control: (1) Cultural — crop rotation, resistant varieties, sanitation, planting time adjustment, field hygiene; (2) Physical/Mechanical — light traps, sticky traps, hand picking, hot water treatment; (3) Biological — predators (Chrysoperla, Coccinellidae), parasitoids (Trichogramma, Bracon), pathogens (NPV, Bt, Beauveria); (4) Chemical — judicious use of insecticides, rotation of chemical groups, correct formulation; (5) Regulatory/Legal — quarantine, PRA, banned pesticides enforcement; (6) Behavioural — pheromone traps, mating disruption. Chemical is the last resort in IPM.

LD50 (Lethal Dose 50) is the dose of a toxicant required to kill 50% of a test population under defined conditions — expressed in mg/kg body weight. A lower LD50 = more toxic compound. Toxicological categories: Class Ia (extremely hazardous, LD50 <5 mg/kg oral), Ib (highly hazardous, 5–50), II (moderately hazardous, 50–2000), III (slightly hazardous, >2000). Endosulfan oral LD50 ≈ 80 mg/kg; Monocrotophos oral LD50 ≈ 14 mg/kg; Malathion oral LD50 ≈ 1,375 mg/kg.

Organophosphates (monocrotophos, chlorpyrifos, malathion) — inhibit acetylcholinesterase (AChE), causing nerve impulse buildup. Carbamates (carbofuran, carbaryl) — reversible AChE inhibitors. Synthetic pyrethroids (cypermethrin, deltamethrin, lambda-cyhalothrin) — keep sodium channels open, causing continuous nerve firing; low mammalian toxicity. Neonicotinoids (imidacloprid, thiamethoxam, clothianidin) — agonists at nicotinic acetylcholine receptors; systemic; highly toxic to bees. Organochlorines (DDT, endosulfan) — axonic poisons; most now banned in India.

Egg parasitoids: Trichogramma chilonis (most widely used in India) — parasitises eggs of Lepidoptera pests including stem borers, bollworms, and sugarcane borers. Larval parasitoid: Bracon brevicornis (ectoparasitoid on caterpillars). Predators: Chrysoperla carnea (green lacewing) — larvae eat aphids, eggs, and small caterpillars; Coccinella septempunctata (seven-spot ladybird) — aphid predator. Viral biocontrol: NPV (Nuclear Polyhedrosis Virus) — Helicoverpa NPV for cotton bollworm control. Fungal biocontrol: Beauveria bassiana and Metarhizium anisopliae.

EC (Emulsifiable Concentrate) — active ingredient in organic solvent + emulsifier; most common formulation. WP (Wettable Powder) — active ingredient + inert carrier + wetting agent; mixed with water for spraying. GR (Granule) — applied to soil or flooding water; e.g., carbofuran 3G for root-zone application. SC (Suspension Concentrate / flowable) — fine suspension in water; no organic solvent. Dust (D) — for dry application. Bait — mixed with attractant. The number after formulation indicates % active ingredient: chlorpyrifos 20 EC = 20% active ingredient.