ECONOMIC INJURY ECONOMIC INJURY LEVEL CONCEPTLEVEL CONCEPT

economic entomology : The scientific economic entomology : The scientific study of pests and pest control strategiesstudy of pests and pest control strategies

pest populations develop, their impact pest populations develop, their impact always results in monetary lossalways results in monetary loss

high density pest pop. high density pest pop. increases increases severity of damage severity of damage need for control need for control more critical. more critical.

TERMSTERMS

INJURY:INJURY: the physical harm or destruction to a the physical harm or destruction to a valued commodity caused by the presence or valued commodity caused by the presence or activities of a pest activities of a pest (e.g., consuming leaves, (e.g., consuming leaves, tunnelling in wood, feeding on blood, etc.)tunnelling in wood, feeding on blood, etc.)

DAMAGE: DAMAGE: the monetary value lost to the the monetary value lost to the commodity as a result of injury by the pest commodity as a result of injury by the pest ((e.g., spoilage, reduction in yield, loss of e.g., spoilage, reduction in yield, loss of quality, etc.). quality, etc.).

Any levelAny level of pest of pest infestation causes injuryinfestation causes injury, , but but not all levelsnot all levels of injury of injury cause damage.  cause damage.  

A low level of injury may not cause enough A low level of injury may not cause enough damage to justify the time or expense of pest damage to justify the time or expense of pest control operations. control operations.

at some point in the growth phase of a pest at some point in the growth phase of a pest population it reaches a point where it begins to population it reaches a point where it begins to cause enough damage to justify the time and cause enough damage to justify the time and expense of control measures. expense of control measures.

But when to start But when to start control?control?

A. How much A. How much financial lossfinancial loss (DAMAGE) is the pest (DAMAGE) is the pest causing?causing?

B. How much will it B. How much will it cost to controlcost to control the pest? the pest?

A pest outbreak occurs whenever A pest outbreak occurs whenever the value of the value of "A""A" is greater than the value of is greater than the value of "B""B".   .  

When A=B When A=B ECONOMIC INJURY LEVEL (EIL)ECONOMIC INJURY LEVEL (EIL)

EILEIL the cost to control the pest the cost to control the pest

equals the amount of equals the amount of damage it inflictsdamage it inflicts

Below EIL, not cost-effective Below EIL, not cost-effective to control the pest to control the pest population because B > Apopulation because B > A

Above EIL, however, the Above EIL, however, the cost of control is cost of control is compensated by an equal or compensated by an equal or greater reduction in damage greater reduction in damage by the pest. by the pest.

A)A) OWNER OF A OWNER OF A

CAMPING SITECAMPING SITE

B) TIMBER BUSSINESS (BALAK)B) TIMBER BUSSINESS (BALAK)

C) MUNICIPAL COUNCIL/MAJLIS PERBANDARANC) MUNICIPAL COUNCIL/MAJLIS PERBANDARAN

D) TAMAN NEGARA/NEGERID) TAMAN NEGARA/NEGERI

SO EIL 320 INSECTS PER ACRE

"C"   is the unit cost of controlling the pest    (e.g., $20/acre) "N"   is the number of pests injuring the commodity unit    (e.g., 800/acre) "V"   is the unit value of the commodity    (e.g., $500/acre)  "I"   is the percentage of the commodity unit injured    (e.g., 10% loss)

The economic injury level (EIL) is often expressed mathematically by the formula:

ECONOMIC THRESHOLDSECONOMIC THRESHOLDS

a point below the EIL at which a decision a point below the EIL at which a decision is made to treat or not treat.is made to treat or not treat.

ECONOMIC THRESHOLS=ACTION ECONOMIC THRESHOLS=ACTION THRESHOLDTHRESHOLD

ETET Always Always lower than EILlower than EIL Expressed in insects density (number of Expressed in insects density (number of

pest per area)pest per area)