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Competency Area 1: Integrated Pest Management (IPM)

PO 5. List types of pest monitoring methods and the advantages and disadvantages of each.

Adapted from: Galen Dively, University of Maryland & University of Delaware Cooperative Extension

Monitoring techniques fall into three types: absolute methods, relative methods, and population indices.

Absolute methods:  this method takes into account estimates of pest population density which are expressed as a level per unit of crop area or as a percentage of the sampling units affected. Examples of this monitoring technique are direct visual counts per plant or per foot of row or per unit of area.
Advantages: broad range of applicability, less influenced by spatial patterns and changes in pest behavior and sampling efficiency, easier to predict potential crop damage.
Disadvantages: More time consuming than other methods

Relative methods: this method gives estimates of pest population activity as a unit of effort or time but not expressed with units of the crop area. Examples of this method include visual searches, sweep net sampling, beating or shake cloth estimates, blacklight traps, pheromone traps, visual sticky traps, and bait traps.
Advantages: yield more data given the same amount of time and effort, i.e. faster and easier to implement.
Disadvantages: efficiency is affected by pest behavior, diurnal activity, weather conditions, the crop habitat being sampled, and variations in the way the methods are deployed; more information is required using this method to relate the relative estimates to potential crop damage.

Population Indices: this method yields estimates of crop damage or the frequency of pest infestations in order to indirectly predict the size of the pest population. Examples are percentage of plants infested or diseased, percentage of defoliation, percentage of damaged fruits, visual ratings of root or foliage injury, etc.
Advantages: the least time consuming of the methods and easy to implement, more directly related to crop yield losses than to actual pest pressure.
Disadvantages: Cannot be used alone to make control decisions, may not allow enough time to take management actions before reaching economic threshold or EIL