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Improving lives by solving problems in agriculture and the environment

INVADERS - Who am I?

Congratulations! You've found the larger grain borer, which has invaded EUDevDays 2016.

Larger Grain BorerEUDevDays 2016

Preferred Scientific Name
Prostephanus truncatus


Maize growing regions

Natural enemies
Teretriosoma nigrescens has been shown to protect maize crops from the larger grain borer

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The larger grain borer is an invasive species which is known to cause maize yield losses of US$91 million per annum in Tanzania and cassava yield losses of US$800 million per annum in West Africa. Farmers have also found that if they grow cassava in areas which are infested with the borer, they are not allowed to export their harvest.


  • Severe losses to staple food crops
  • Limits exportation of crops
  • Reduces native biodiversity
  • Negatively impacts livelihoods

Chemical control 

The most effective method of controlling larger grain borer is the use of synthetic pyrethroid insecticides such as permethrin and deltamethrin. However, these insecticides have proved to be ineffective against other storage pests, such as Sitophilus spp, which are found in the same pest complex as the invasive beetle. These other pests have proven more susceptible to organophosphorus pesticides. A combination of these and the synthetic pyrethroid insecticides provide an effective method for protecting farm-stored grain from pests, as long as high quantities are applied relatively frequently. 

Biological control

The predator Teretrius nigrescens has been indicated as a biocontrol solution to the larger grain borer. However, despite becoming quickly and easily established across large parts of Africa, it has not reduced the density of the pest by enough for it to be considered a biocontrol agent.

However, it does meet the impact criteria to be considered an important part of the integrated pest management system for dealing with the beetle. 

For more information about plant pests and their diseases and how to manage them, visit the Plantwise Knowledge Bank.

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