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close this bookAn Overview of Disaster Management (Department of Humanitarian Affairs/United Nations Disaster Relief Office - United Nations Development Programme , 1992, 136 p.)
close this folderChapter 4. Natural hazards
close this folderCharacteristics of particular hazards and disasters 1
View the document(introduction...)
View the documentEarthquakes
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View the documentLandslides
View the documentTropical cyclones
View the documentFloods
View the documentDroughts
View the documentEnvironmental pollution
View the documentDeforestation
View the documentDesertification
View the documentPest infestations
View the documentEpidemics
View the documentChemical and industrial accidents

Pest infestations

Causal phenomena

Increase in pest numbers due to one or a combination of ecological factors including temperature, monoculture of crops, introduction of plants to new locations, introduction of pest species, overcoming genetic resistance in host, overcoming pesticide effects, conducive weather patterns, migration.

General characteristics

Plants can be damaged in various ways such as consumption of parts, tunnelling in stems, attack of root systems, injection of toxins.


Pest forecasting determines whether application of a pesticide will be cost effective, by examining the stages of development of the crop and the pest and by determining the economic threshold.

Factors contributing to vulnerability

Large numbers and varieties of pests
Lack of controls on imported plant products
Constraints on resources to predict and treat pest infestations
Insufficient crop yields in normal times
Areas inaccessible to surveillance for pests
Underdevelopment of agricultural technologies

Typical adverse effects

Crop losses could lead to food shortages, even famine, and stress economic systems.

Possible risk reduction measures

Integrated pest management employing appropriate methods of physical control, cultural control, crop plant resistance, biological control, legislation, chemical control and possibly eradication.

Specific preparedness measures

Establishing a national plan for pest control
Training for government personnel and extension to farmers

Typical post-disaster needs

National or international control efforts
Provide needed food supplies

Impact assessment tools

Assessment of incidence and severity of infestation
Aerial and ground surveys of damage to crops