Larger grain borer (Prostephanus truncatus) risk assessment and control in farm maize stores

Partners:

Ministry of Food and Agriculture, Tamale, Ghana

Problem:

To African small-holders, food and financial security are often represented by stored grain and other commodities.  These are subject to attack by a complex of insect pests including the larger grain borer (LGB); an especially damaging species from Central America now endemic in many parts of sub-Saharan Africa.  LGB can be utterly devastating to maize and dried cassava, with infestation often reducing sound stock to dust in a relatively short time.  Moreover because of its recent introduction to Africa and the sporadic nature of its outbreaks – over time and space – farmers (and extension staff) are frequently been taken by surprise. 

Achievements:

To tackle this problem an LGB risk warning system, based around a model of LGB flight activity driven by climate data, was completed in 2002 that enables well equipped extension services to warn farmers of coming bad years and so take action to reduce the severe damage expected.  Typical action by farmers is to apply insecticide to their stored crop but this is expensive.  To reduce the costs of treating the portion of the crop that farmers will be consuming during the storage season, a method of targeted insecticide application was developed.  This reduces by at least 70% the amount of pesticide applied to stores but still provides good protection.  This is achieved by treating only the bottom 30% of traditional maize cob granaries or small bulks of maize grain.  However, maize for longer-term storage may require the usual full treatment.