Foliar insect pest management on cowpea (Vigna unguiculata Walpers) in simulated varietal mixtures.: I. The suitability of partial insecticide applications

This research described in this paper examined the impact of varietal mixtures on pest management utilising a model system of partial insecticide applications. In six field experiments conducted in 1995 and 1996 in Igalaland, Kogi State, Nigeria varietal mixtures were simulated through the application of systemic insecticide (carbofuran or furathiocarb) to a pre-determined percentage of a cowpea (Vigna unguiculata) crop. The objective was to examine and compare the pest damage on untreated cowpea plants grown in plots in which varying percentages of the cowpea plants were treated with insecticide. A secondary objective was to determine whether action of the foliage pests influenced flower production. The results showed that the presence of insecticide-treated plants reduced the level of leaf damage by Ootheca mutabilis Sahlberg and the densities of Aphis craccivora Koch populations on untreated plants. The greater the percentage of insecticide-treated plants the greater this reduction on the untreated plants. Meanwhile, the number of flowers found on the untreated plants increased suggesting the foliage pest damage reduced flower production.