CHAPTER ONE 1.0
GENERAL INTRODUCTION 1.1
Introduction
Grains constitute the most important staple food for the growing population in most parts of the world and are usually stored to provide food reserve and seeds for planting (Niber, 1994). Maize is a very important crop of the world after wheat and rice (Purseglove, 1992). Maize (Zea mays) originated in America, and is now the principal cereal crop in the tropics and sub-tropics (FAO, 1992). In Ghana, maize is the largest staple crop and is the mainstay of the diet of the majority of Ghanaians, because it is the base for several traditional food preparations (such as banku, kenkey, tuozafi) (Morris et al., 1999). Additionally, it represents the second largest commodity crop in the country, after cocoa (ISSER, 2012). Maize is also the main component for poultry and livestock feed (Asiedu et al., 2002). Maize accounts for 50 – 60% of the total cereal production in Ghana (Egyir, 2003; ISSER, 2012). The total average annual maize production in Ghana between 2007 and 2012 was 1.5 million MT (MoFA, 2012), which indicates that maize supply in Ghana has steadily been increasing over the past few years. It is estimated that Ghana is about 99% self-sufficient in domestic maize production, therefore proper storage practices should be done in order to reduce postharvest losses to major storage insect pests which has been recognized as an increasingly important constraint to food security. Many factors including biotic (insect pests, mites, rodents and micro-organisms) and abiotic (high moisture content, relative humidity and temperature) account for the post-harvest losses of University of Ghana http://ugspace.ug.edu.gh 2 maize both in the field and storage and are responsible for the decline in quality, nutrition and germination potential in storage (Forsyth, 1962; Devereau et al., 2002). Stored maize is attacked by 20 different species of insect pests (Mould, 1973; Ayertey, 1979). Some of the major insect pests of stored maize are Sitophilus zeamais Motsch (Coleoptera: Curculionidae), Tribolium castaneum Herbst (Coleoptera: Tenebrionidae) and Prostephanus truncatus Horn (Coleoptera: Bostrichidae). In Africa the estimates of maize grain losses in storage vary but are known to be in the range of 20–30% (Markham et al., 1994; Van Gastel et al., 1999; Lamptey, 2000; Nyanteng and Asuming – Bempong, 2003; Egyir, 2003). In Ghana, there are reports of losses averaging 30% or more of grain dry weight in maize stored on farm due to infestation by Tribolium castaneum (Herbst), Sitophilus zeamais (Motsch) and Sitotroga cerealella (Olivier) (IITA, 1995; Egyir et al., 2008); and out of an estimated total annual harvest of 250,000-300,000 tonnes of maize about 20-25% is lost to S. zeamais alone (Ayertey, 1982; Obeng-Ofori and Amiteye, 2005). Such losses lower both the incomes and standard of living of farmers and also lead to wastage of a large proportion of the contribution to the nation‘s food supply and can pose a serious threat to the nation‘s food security (Asiedu and Van Gastel, 2001; FAO, 2004). Apart from the actual nutrient losses, kernels damaged by insects may be contaminated with dangerous levels of aflatoxins (IITA, 1995). Additionally, there is contamination by dead beetles, pupae and larval cocoons, some of which contain highly dangerous substances (IITA, 1995).
