Demand-Driven Technologies for Sustainable Maize ... - IITA

316In Cameroon, maize is commonly intercropped with several othercrops namely groundnut (Arachis hypogaea L.), cassava (Manihotesculenta Crantz.), soybean (Glycine max Merril.), beans (Phaseolusspp.) and cowpea [Vigna unguiculata (L.) Walp]. Cowpea is grownfor its high nutritive value, as it is one of the main sources of proteinsfor the majority of the population in Africa (Ta’Ama 1983, 1988).Furthermore, its nitrogen fi xing ability, as in most other grain legumes,is of special importance in enriching the soil (Giller and Wilson 1991;Giller et al. 1991; Reynolds et al. 1993).Aroga and Coderre (2000) found that the population densities ofstem borers on maize were signifi cantly reduced in central Cameroonthrough intercropping of maize with groundnut. However, informationabout the effects of maize-cowpea intercropping on the dynamics ofmaize stem borer population buildup and associated natural enemiesis lacking. The objectives of this study were, therefore, to (i) assess theeffects of intercropping maize with cowpea on the abundance anddiversity of maize stem borer species and associated natural enemies,and (ii) determine the economic profi tability of this cropping systemrelative to maize crop treated with insecticide and monocropped maizeas an untreated control.Materials and MethodsResearcher-managed trialsTwo researcher-managed trials were conducted in farmers’ fi elds inNyom II (forest zone) and Bafi a (forest-savanna transition zone). Theexperimental design at each site was a randomized complete blockwith 3 treatments: (i) maize treated with Carbofuran 1 , (ii) monocroppedmaize, and (iii) maize-cowpea intercropping. The maize variety CMS9015 and cowpea variety BR1 were planted the same day in alternaterows at a population density of 50,000 plants per hectare, with aspacing of 0.25 m between plants and 0.80 m between rows. Eachexperimental plot was 26.4 m 2 (6.6 m x 4 m). The compound fertilizer20-10-10 NPK was applied to the maize at the rate of 500 kg ha -1four weeks after planting (WAP). Granules of Carbofuran were appliedsix weeks after planting at the rate of 15 kg ha -1 in the maize whorlof the plots protected with insecticide. Weed control was performedmanually as necessary.Farmer-managed on-farm trialsTwenty farmer-managed on-farm trials were established during the2001 dry season. The trial in each farm was laid out as a randomizedcomplete block design with the same three treatments as described1Trade name is Furadan