Alligator pepper, Aframomum melegueta, and ginger, Zingiber officinale, reduce stored maize infestation by the maize weevil, Sitophilus zeamais in traditional African granaries

Alligator pepper, Aframomum melegueta (Roscoe) K. Schum, and ginger, Zingiber officinale Roscoe were tested for their efficacy in protecting stored maize cobs (Zea mays L.) against the maize weevil, Sitophilus zeamais Motschulsky, in traditional maize storage barn conditions, from November 2006 to February 2007, and November 2009 to February 2010 in Obudu, Southeast Nigeria. A randomised complete block design was used in each storage barn with four treatments (maize, maize plus A. melegueta, maize plus Z. officinale, maize plus A. melegueta and Z. officinale) replicated 4 times. When used in combination with stored maize cobs at a level of 10% (w/w), A. melegueta and Z. officinale significantly reduced S. zeamais populations from cobs (P < 0.001), as did a combination of A. melegueta and Z. officinale (5% w/w each, P < 0.001). Furthermore, significantly higher seed germination was observed in treated cobs compared with the untreated cobs in both trials (P < 0.001). Protection of cereals with such repellent materials has important practical applications in parts of the world where insecticides are expensive or in short supply, and where these materials are cheap and readily available for local use by resource-poor farmers. In addition, the use of repellents to protect stored maize grains has the potential for minimising the requirement for broad-spectrum toxic insecticides, thereby reducing the development of insecticide resistance.