On Purdue Improved Cowpea Storage (PICS) technology: Background, mode of action, future prospects

• The story of the Purdue Improved Cowpea Storage (PICS) Technology is reviewed.
• Physical activity and reproduction of bruchids in PICS bags ceases due to hypoxia.
• Hypoxia is due to insect metabolism and oxygen barriers presented by the bag walls.
• Oxygen deprivation deprives the bruchids of their most important source of water.
• Low-resource farmers in West African countries helped shape the PICS technology.

Hermetic or airtight storage of grain to suppress development of destructive populations of storage insect pests is an ancient technology that is finding modern applications in developing nations. Unprotected cowpea grain can be destroyed by unchecked growth of the bruchid, Callosobruchus maculatus (Walp). If the grain is kept in triple-layer hermetic plastic bags, losses are averted. The history, development and mode of action of triple-layer bagging for cowpea storage is reviewed here, as are lessons learned while bringing the technology to low-resource farmers in the developing nations of West and Central Africa. The success of the technology owes in part to the engagement of low resource farmers at virtually all stages of development, testing and extension of the technology.