Production, safe storage, trade and utilisation of grain remain a vital part of the world economy. Grain is the staple food in many countries, is extensively used in processed food and is an important ingredient in animal feeds. It therefore is important to both developed and developing economies.

The Stored Grain and Oilseed Unit is committed to the provision of high quality investigations, monitoring, research and technology transfer services to determine requirements and technical means of safe and insect-free small farm storage, medium storage and large scale storage of grain.

Activities in the Unit

The Stored Grain and Oil Seed Research Unit does research and can be of assistance in the following activities:

  • Breeding and supply of the most common stored grain insect pests in South Africa

  • To determine post-harvest constraints facing small-scale farmers and to improve post-harvest management strategies for improving household food security

  • Product development and assistance with registration of stored grain pesticides for large and small-scale storage facilities. A registration trial can include a pesticide application, biological efficacy trials, organoleptic tests, germination trials as well as residue analysis of the treated grain

  • Evaluate the registered phosphine fumigation products in South Africa to ensure that all products comply with the registration requirements as stated on the label of these products

  • Rodent control research to determine the impact of trapping on stored grain losses and on rodent populations amongst rural communities

  • Monitoring the distribution of invasive stored grain insect pests e.g. the larger grain borer.

History of the stored grain insect culture 

The origin of the insects of stored grain is not well known. Undoubtedly they lived in the fields in the seeds that escaped the attention of the birds. Humans began to cultivate plants around 8000 BC in the Middle East, the custom to store seeds for food, adopted by man during this time, provided an easy living for insects accidentally brought in with the seeds. Ideal conditions for breeding, provided by these stores, made it unnecessary for these insects to search for additional food. They adapted morphologically in size, colour and shape to go unnoticed in grain and be carried by grain handlers to all parts of the world. Supplies of grain placed in the tombs of ancient Egyptians were destroyed by the same species that we are familiar with today. The rust red flour beetle (Cryptolestis ferrugineus) was found in a tomb of a pharaoh dating back 1345 BC.

The stored Grain and Oilseed Research Unit has an insect culture consisting of 11 stored grain insect species commonly found in South Africa. PPRI – Stored Grain is currently the only organisation in South Africa specializing in stored grain insects. The University of Pretoria, University of Stellenbosch, the SABS, the CSIR and other PPRI divisions often use stored grain insects reared from this culture for their own trials. All the stored grain pesticide registration trials done by the unit make use of these insects to determine biological efficacy of the tested pesticides. Five phosphine susceptible insect species were especially imported from Canada and England to ensure phosphine resistant trials in South Africa. Currently the unit also has a field culture strain from the Cape Province to conduct contact pesticide resistance trials. The laboratory insect strain, which consist of the 11 species, is more than 20 years old. Three breeding rooms at specific temperatures are used to house these insect species. The rooms are calibrated on a three-year interval to ensure that the insects are kept at optimum breeding temperatures. Two adjacent smaller breeding rooms are used for the incubation of the insects during registration or pesticide resistant trials.


Ephestia cautella

Rhyzopertha dominica

Sithophilus zeamais

Contact: Research Team Manager: Dr Roger Price, E-mail:, Campus: Roodeplaat (East), Pretoria

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