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

322were the predominant predator species in each location and treatment.They were slightly more abundant in Bafi a (51%) than in Nyom II(49%), and species diversity indices were slightly higher in Bafi a thanin Nyom II. No particular pattern of species distribution was observedamong the treatments.No parasitoid emerged from the larvae collected. However, thefollowing fi ve fungi species were recovered from 24 of the larvaecollected: Beauvaria bassiana, Fusarium moniliforme, F. oxysporium, F.semitectum, Aspergillus niger, Penicillium and Chaetonium. All the fungiwere found on larvae collected from both locations, except Chaetoniumthat was recovered from larvae collected in Bafi a. F. moniliforme waspredominant (recovered from 42% of larvae), followed by Penicillium(25%), B. bassiana (17%), A. niger (12%) and Chaetonium (4%).Economic analysisTotal revenue per hectare derived from maize treated with Carbofuranwas 500,000 FCFA and 275,000 FCFA for the maize component inthe maize-cowpea intercrop. Additional revenue of 480,000 FCFAwas obtained from the cowpea component of the intercrop (Table6). Total costs were 69,065 FCFA for maize treated with Carbofuranand 55,565 FCFA for the intercrop. Subtracting total variable costsfrom total revenue gave net profi ts of 430,935 FCFA for Carbofurantreatedmaize and 699,430 FCFA for intercrop. Thus an additionalbenefi t of 268,495 FCFA was derived from intercropping. Therefore,maize-cowpea was more profi table than the use of Carbofuran tocontrol stem borers of maize.DiscussionThe stem borer species B. fusca, S. calamistis, E. saccharina and M.nigrivenella were present in all the treatments, but their diversityindices were low in maize treated with Carbofuran. The high indicesfound in the untreated (control) plots within the same locationsuggests that maize borer species were more diversifi ed in untreatedthan intercropped or treated plots. In addition, the species were morediversifi ed in Bafi a than in Nyom II. These results are consistent withthose of Legendre and Legendre (1979), who suggested that lowdiversity indices indicated a higher biological activity of some species.In other words, low indices correspond to a less equitable speciesdistribution. Overall, the results of the present study showed that B.fusca was the predominant species in all treatments in Nyom II as wellas in Bafi a.Incidence of the borers was higher in untreated plots than in theother treatments. The low number of borers on the maize-cowpeaintercrop supports the resource concentration hypothesis of Root