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close this bookManual on the Prevention of Post-harvest Grain Losses (GTZ)
close this folder7. Important pests in storage
View the document(introduction...)
View the document7.1 Identification of pests
View the document7.2 Classification of storage pests
View the document7.3 Development of insects
View the document7.4 The effect changes in climate on development
View the document7.5 The use of various sources of food by pests
View the document7.6 Morphological features of insects
View the document7.7 Storage pest species
View the document7.8 Further literature

7.5 The use of various sources of food by pests

Stored product insects have different requirements as to the composition of their food:

· Primary pests are able to teed on whole, healthy and well-storable grains.
Examples: weevils, lesser grain borer (Rhyzopertha dominica). Angoumois grain moth (Sitotroga cerealella)

· Secondary pests can only attack broken grain, moist, and thus soft grain, grain damaged by primary pests or processed products, e.g. flour.
Examples: flour beetles

· Mould indicating pests live partially or entirely on fungi and their presence reveals problems with moisture.
Examples: Black fungus beetle (Alphitobius diaperinus), Foreign grain beetle (Ahasverus advena)

· Scavengers live largely on dust, the excrements of other insects or dead insects. They do not usually feed on the stored produce itself but often pose a serious hygienic problem.
Examples: dust lice

· Predators live entirely or partially on insects, mostly on eggs and larvae (see section 10.2).
Examples: Teretriosoma nigrescens, Wheat beetle (Tenebroides mauritanicus)

Some storage pests also prey mm the larvae of other species. Their use in reducing infestation is, however' far less than the damage they themselves cause by feeding on the stored produce.
Example: Tribolium castaneum

Whether an insect can make use of stored produce as a source of food depends on a number of factors:

Most storage pests are able to penetrate a stack of bags far more quickly and thoroughly than bulk produce because of the gaps between the bags. The size, the surface texture and nutrients in the grain influence the ability of the pest to attack the commodity. This applies also for packaging material and the state of the store itself