Economic entomology
" as the scientific study of pest and pest control strategies that recognize the financial impact insects have on the industry, agriculture, and human society in genera
Injury
is defined as the physical harm or destruction to a valued commodity caused by the presence or activities of a pest (e.g., consuming leaves, tunneling in wood, feeding on blood, etc
Damage
is the monetary value lost to the commodity due to injury by the pest (e.g., spoilage, reduction in yield, loss of quality, etc.)
but not all injury can cause damage
Any level of pest infestation causes injury
Pest outbreak
occurs whenever the value of "A" is greater than the value of "B.
on potential losses rather than the expected loss
Househould losses are estimates of damage are often based
Commodity values are well established in commerce and trade
Actual losses are relatively easy to measure in agricultural or industrial settings because
Economic Injury Level
The break-even point, where "A" = "B," is known as the economic injury level, which is the population density at which the cost to control the pest equals the amount of damage it inflicts
Measurement of injury
Occasionally, when the insects themselves are difficult to count or detect, EIL may be based on a
cost of pest control and the value of the commodity
It is essential to recognize that the economic injury level is a function of both the
Economic threshold level
a useful concept because it quantifies the cost/benefit ratio that underlies all pest control decisions.
Economic threshold level
is defined as the pest density at which steps are first taken to ensure that a potential pest population never exceeds its economic injury level.
insects density units or injury measurement
the economic threshold is usually expressed in
Disease incidence
is used for measuring diseases that affect whole plants (bacterial wilt, mosaic diseases and systemic diseases such as bacterial or fungal wilt and virus diseases.
Disease Severity
In case of localized infection injury is expressed as ________ can be the percent of leaves infected for the whole plant or the • percentage of leaf area infected
20 insects per hill
green leaf hopper ETL during mid tillering panicle initiation to booting
10 insects per hill
green leaf hopper ETL during in other areas at the tillering stage
20% damage
Rice in other areas at the tillering stage
5% deadheart
ETL of Stem borer Moderate to severe in the nursery,
One egg mass/m2
ETL of rice stem borer at rice field area at tillering stage
One moth/m2
ETL of rice stem borer at panicle initiation to booting or flowering stages
Brown plant hopper
the cause of hopper burn and the vector of ragged stunt virus disease
5 to 10 insects per hill
ETL of BPH @ tillering stage.
20 insects per hill,
ETL of BPH @ panicle initiation and booting stage
5-10 insects per hill
ETL of BPH @ at flowering stage and after flowering
3-4 egg mass/100 plant
ETL of corn borer @whorl stage
40% or more
ETL of core borer @ post-tassel