In agriculture, substantial losses in crop produce take place due to the infestation of different pests and diseases. These losses can be decreased to a great extent when their occurrence is recognized in advance so that timely remedial measures can be taken. Therefore, there is as well a requirement to build up forewarning systems that can give advance information for outbreak of pests/diseases attack so that protection evaluates can be implemented prior to the actual onset of the damage.
Monitoring phytophagous insects and their natural enemies is a basic tool in IPM - for taking the management decision.
Signifies to the constant watch on the population dynamics of pests, its incidence and damage on each and every crop at fixed intervals to forewarn the farmers to take up timely crop protection measures.
Three fundamental components of pest surveillance are as follows:
Objectives of Pest Surveillance:
Forecasting of pest incidence or outbreak based on the information attained from the pest surveillance.
Two kinds of pest forecasting:
a) Short term forecasting: Mainly based on 1 or 2 seasons.
b) Long term forecasting: Mainly based on the influence of weather parameters on the pest.
Precise forecasting of pest attacks helps control program to be efficient. It mainly based on the established relationship between the given factors:
Survey of pest species:
It is basically conducted to study the profusion of the pest species. There are two kinds of survey:
1) Roving survey:
2) Fixed plot survey:
Evaluation of the pest population or damage from a fixed plot chosen in a field. The data on pest population or damage recorded periodic from sowing till harvest. Example: 1 sq.m. plots arbitrarily chosen from 5 spots in one acre of crop area in case of rice. From each plot 10 plants chosen at arbitrary. Net tillers and tillers influenced by stem borer in such 10 plants counted. Total leaves and number influenced through leaf folder noticed. Damage expressed as percent damaged tillers or leaves. The population of BPH from all tillers in 10 plants noticed and deduced as number or tiller.
Absolute sampling: Mainly used to count all the pests taking place in a plot.
Relative sampling: To calculate pest in terms of certain values that can be compared over time and space example: Light trap catch and Pheromone trap.
Methods of sampling:
a) In situ counts: Visual observation on the number of insects on plant canopy (that is, either whole plot or arbitrarily chosen plot)
b) Knock down (Sudden trap): Gathering insects from a region through eliminating from crop and counting.
c) Netting: Utilization of sweep net for hoppers, odonates and grasshopper.
d) Narcotized collection: Quick moving insect's anaesthetized and counter.
f) Crop samples: Parts of plant eliminated and pest counted example: Bollworms
Stage of Sampling:
Economic Injury Level:
EIL = C / (V x I x D x K)
EIL = C / VIDK
EIL = Economic injury level in insects or production (or) insects/ha
C = Cost of the management activity per unit of production (Rs./ha)
V = Market value per unit of yield or product (Rs./tonne)
I = Crop injury per insect (Per cent defoliation/insect)
D = Damage or yield loss per unit of injury (Tonne loss/percent defoliation)
K = Proportionate reduction in the injury from pesticide use Economic threshold level (ETL) or Action threshold
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