Management Approaches:
Host Plants

Rice

The indigenous African rice, Oryza glaberrima, or red rice, probably originated in the Niger delta about 3500 years ago, and was widely cultivated in that area.  Its cultivation is now largely restricted to northern Nigeria and Sierra Leone, having been replaced by the imported Asian Oryza sativa.  Oryza sativa varieties grom Guyana and Sri Lanka were introduced into Nigeria in about 1890, but the date and origin of the first introductions of O. sativa into Africa are not know.  While some suggest it was brought to the west coastal regions by Portuguese traders, it is equally likely that O. sativa came by trans-Saharan caravan routes (Grist, 1983).  Oryza sativa is grown as many different varieties or cultivars, depending on the type of rice cultivation.  Nigeria is the only African country south of the Sahara currently producing rice in any quantity, most African countries relying largely on imported rice.  Within the Afrotropical region, Madagascar is another important rice producer.

There are two fundamental kinds of rice cultivation, deep-water (submerged) and upland (non-submerged) , both of which are to found in Africa.  Further subdivisions of these categories to br found in Africa are as follows:

1. Deep-water (fluxial) rice.
a. Mangrove rice.  Found at river estuaries and periodically invaded by salt water, mangrove rice cultivation is affected to a great extent by salinity.  About 10% of all African rice is grown in mangroves along the West African coast from Gambia to Nigeria, in particular in Guinea-Bissau, Senegal and Sierra Leone.
b. Freshwater rice.  Deep-water, non-irrigated rice cultivation (= lowland swamp) accounts for 23% of all African rice cultivation.  Flotation rice cultivation, an extreme example of deep-freshwater rice cultivation, can be found in Mali and Niger.  Deep-water irrigated rice cultivation, common in Asia, accounts for less than 5% of the total African rice cultivation.

2. Upland rice.
a. Pluvial (dryland) or rain-fed rice.   Sixty per cent of the toal area under rice cultivation in Africa is rain-fed.  A few countries account for the majority of acreage: Ivory Coast, Zaire, Sierra Leone, Liberia, Nigeria and Madagascar.
b. The remaining 2.5% of African rice is what is known as hydromorphic or phreatic, where cultivation occurs on land watered by the retreating high groundwater level.  In West Africa, this is known as rizeculture de nappe.

The most important stem borers attacking rice in Africa are the noctuid Sesamia species, in particular S. calamistis.  Busseola fusca has been reported from rice very occasiomnally.  Among the Crambidae and Pyralidae, several Chilo species, in particular C. zacconius, are rice pests.  Maliarpha separatella can be an important pest of rice.  Several Scirpophaga species attack rice in Africa but, although they can be locally or periodically important, they are never the major pests that Scirpophaga species constitute in Asian rice.  Eldana saccharina can also be found in rice.

Major references: Angladette, 1966; Buddenhagen and Persley, 1978; Grist, 1983; Jacquot and Courtois, 1983; Anon., 1984; IITA., 1984; Alam et al., 1985; Khan et al., 1991.