This study compared the effect of supplementing maize stover (MS) with cowpea (Vigna unguiculata) haulms or commercial concentrate (CC) on feed intake, nutrient digestibility, live weight gain and carcass yield of male Ethiopian Highland sheep. Two cowpea genotypes, 12688 (forage) and IT96D-774 (dual-purpose), were used. A randomised block design was applied with groups of eight sheep, blocked by weight, allocated to one of six treatments; MS ad libitum either unsupplemented or supplemented daily with 150 or 300 g dry matter (DM) of either cowpea or CC. MS contained more neutral detergent fibre (NDF), acid detergent fibre (ADF) and lignin than either cowpeas or CC. Crude protein (CP) content of the forage-type cowpeas was higher than either dual-purpose or CC, while MS had the lowest CP content. Relative to the negative control group, cowpea at either level significantly (P < 0.01) increased both MS intake and total NDF and lignin. Supplementation significantly (P < 0.01) increased nitrogen (N) intakes relative to the negative control, with N intake for CC and dual-purpose cowpea (high level) being similar to the intakes for cowpeas at 150 g. N intake with the forage-type cowpea offered at higher levels was significantly (P < 0.01) greater than the other groups. No significant differences (P > 0.01) in MS intake were identified between cowpeas at either level or CC and, although intake level of CC increased, it did not differ significantly from the negative control group. Supplementation significantly (P < 0.01) improved average daily gain, with the negative control group losing weight over the experimental period, and increased final live weight, carcass cold weight and dressing percentage. Supplementation significantly improved the apparent digestibility of DM, organic matter and NDF, with no significant difference found between cowpeas at either level. N retention was negative for sheep offered only MS, but positive with all supplements, with cowpeas improving N retention to a greater extent than CC. Interestingly, N retention/N intake was higher with cowpeas offered at the lower level suggesting an improvement in utilisation efficiency. The results indicate that the supplementation of MS with cowpea enhanced ruminant production through improvements in digestibility and intake. Further, as production improvements associated with the two levels of supplementation did not differ significantly, it is suggested that where limited quantities of cowpea are available, it may be of greater nutritional benefit to offer smaller quantities over an increased number of animal days.

The effect of mixed cropping cow pea with maize on general predators' abundance and their influence on population density of Megalurothrips sjostedti (Trybom) on cowpeas was investigated in the field and in exclusion cages. Populations of predatory ladybird beetles, Orius sp. and earwigs (Dermaptera) were not significantly influenced by mixed cropping. The density of spiders, however, was significantly higher in the cowpea sole crop than in the cowpea/maize mixture. The population density of M. sjostedti was significantly less in the cowpea/maize mixture than in cowpea sole crop, both inside cages, where predators were excluded, and outside. We concluded that this reduced population density was not the result of enhanced predators’ population in the mixture.

The effect of growing cowpeas mixed with either beans or maize on population densities of Megalurothrips sjostedti (Trybom) was investigated. Also investigated was the effect of varying the cropping densities of the host plants on the pest populations.

There was a significantly lower population of M. sjostedti in cowpea/maize, bean/maize, and cowpea/bean/maize mixed stands as compared with that in either cowpea/bean stands or monoculture stands of cowpeas and beans. Increasing the cropping densities of the host crops increased the abundance of the pest in non-maize based mixed stands, but this effect was not observed in the maize-based mixed stands.

The results indicate that with regard to infestation by M. sjostedti, the practice of mixed cropping beans with cowpeas confers no advantage to either crop with respect to attack by M. sjostedti. On the contrary, combining the two crops attracted infestation levels similar to those attracted by either crop grown in monoculture. But the inclusion of a non-host plant (maize) in the mixture, significantly reduces infestation.

Six foliar insecticides were evaluated for efficacy in the control of different stages of Clavigralla tomentosicollis, the most important cowpea coreid in Nigeria.

Monocrotophos was highly effective in controlling adults for up to 16 DAT and was statistically better than cypermethrin + dimethoate (Sherpa Plus(R)), deltamethrin, endosulfan and deltamethrin + endosulfan 8 days after treatment. Comparative overall results were obtained between monocrotophos and the mixture of cypermethrin + chlorpyrifos. The best control of nymphs was obtained with monocrotophos, cypermethrin + dimethoate and endosulfan, while the mixtures of cypermethrin + dimethoate and cypermethrin + chlorpyrifos completely inhibited egg hatch. More than 78% egg hatch was obtained from monocrotophos and deltamethrin, while the water-treated control had 96% hatch.

These findings are discussed in the light of product toxicity, residual action and overall reduction of the pod bug populations.

The legume pod-borer, Maruca testulalis, continues to be a major limitation to successful cowpea cultivation in many countries. During the past decade, research on this insect has increased in scope and intensity at international agricultural research centres and a number of universities. The work that has been done on the biology and control of this pest at the International Institute of Tropical Agriculture (IITA) is briefly discussed with emphasis on the development of a management strategy centred around host plant resistance, and some suggestions for future research direction are given.