1. Damage Boundary (DB)

The lowest level of injury that can be measured; occurs before economic loss begins.

Also called Damage Threshold (Pedigo et al., 1986).

2. Economic Injury Level (EIL)

The lowest pest population density that causes economic damage.

Defined by Stern et al., 1959; also called Damage Threshold Level (DTL).
👉 Formula: EIL = C / (V × D × K) where:
C = cost of control,
V = market value of crop,
D = yield loss per pest,
K = effectiveness of control.

3. Economic Threshold Level (ETL)

The pest density at which control measures must be applied to prevent the population from reaching the EIL.

Also called Action Threshold. ETL < EIL.

4. General Equilibrium Position (GEP)

The average population density of a pest over a long period, in the absence of control measures.

Depends on environmental and ecological factors.

1758

Carl Linnaeus introduced binomial nomenclature in Systema Naturae.

“Father of Taxonomy.”

1840s–1850s

William Kirby regarded as the Father of Entomology.

Co-authored Introduction to Entomology with Spence.

1901

Lionel de Nicéville — First Govt. Entomologist in India.

1903

H.M. Lefroy — Second Govt. Entomologist of India.

Authored Indian Insect Life.

1914

Destructive Insect Pest Act (DIPA) enacted in India.

First legal insect pest control law.

1938

Hem Singh Pruthi founded the Entomological Society of India.

1946

DPPQS (Directorate of Plant Protection, Quarantine & Storage) established at Faridabad, Haryana.

First quarantine institute in India.

1951

R.H. Painter coined “Resistance” and wrote Insect Resistance in Crop Plants.

Father of Host Plant Resistance.

1959

Stern et al. introduced the Economic Injury Level (EIL) and Integrated Control Concept.

1962

Rachel Carson published Silent Spring.

Environmental awareness milestone.

1964

Paul DeBach published Biological Control of Insect Pests and Weeds.

Father of Biological Control.

1968–1971

Insecticides Act (1968) enforced from Jan 1, 1971 in India.

Legal control of insecticides.

1973

Development of first photostable pyrethroid — Permethrin.

Synthetic pyrethroid era begins.

1975

Elcar (Helicoverpa NPV) registered for bollworm control on cotton.

First viral biopesticide.

1987

M. Vaeck et al. (Plant Genetic Systems, Belgium) developed the first transgenic plant (Bt tobacco) using Bacillus thuringiensis endotoxin gene for control of Manduca sexta.

Start of transgenic pest control.

Pheromones

Chemicals mediating communication between individuals of the same species.

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Sex pheromones in moths

Kairomones

Chemicals that benefit receiver but harm releaser.

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Plant volatiles attracting pests

Allomones

Chemicals that benefit releaser but harm receiver.

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Defensive secretions in beetles

Synomones

Benefit both releaser and receiver.

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Plant volatiles attracting parasitoids