Abstract
Aphids (Aphis craccivoraKoch) are an important vegetative stage pest of cowpea in Africa. The use of resistant cultivars is among the best management option for this pest, but the success of this strategy is influenced by the stability of the resistant genotype to the cowpea aphid biotypes present in the major cowpea growing areas in a country. This work, therefore, aimed at identifying cultivars/genotypes with stable resistance to aphid infestation across different cowpea growing ecologies in Ghana and estimating yield loss due to aphid infestation at the seedling stage. To ascertain the stability of aphid-resistant cultivars/genotypes, four cultivars/genotypes (SARC1-57-2, SARC1-91-1, IT97K-499-35, and Zaayura) and a susceptible check (Apagbaala) were tested across 18 locations in Ghana. An on-station experiment was used to quantify yield losses due to aphid attack at the seedling stage in the five cultivars/genotypes mentioned above together with 5 additional cultivars/genotypes [i.e., IT99K-573-3-2-1, IT99K-573-1-1, Padituya, Resistant BC4F3(Zaayura//(Zaayura × SARC1-57-2)), and Susceptible BC4F3(Zaayura//(Zaayura × SARC1-57-2))]. The results showed that SARC1-57-2 was stable in all ecologies, in terms of its resistance to aphids; it had high vigour score (3.8 ± 0.03) and low plant mortality (3.7 ± 0.22%) compared to the susceptible genotypes. The number of days to flowering and maturity were significantly higher in aphid-infested plants than in the uninfested ones. Grain yield loss was estimated to range between 3.8 and 32.8%. Except for SARC1-57-2, Resistant BC4F3,and Padituya, the remaining cultivars/genotypes sustained significant yield losses under aphid infestation. Thus, the aphid-resistance gene in SARC1-57-2 is stable against aphids. This resistance genotype can be incorporated into cowpea improvement programmes to breed for aphid-resistant cultivars. Also, the cultivation of such improved cultivars will reduce pesticide usage in cowpea production.
Highlights
Cowpea (Vigna unguiculata (L.) Walp) is mostly cultivated in tropical Africa, and its edible seeds constitute a major source of protein [1]
One of the major constraints in the production of cowpea in Africa is severe infestation and damage by various insect pests in the field [2]. is is because of its long history of cultivation on the continent. us, it is prone to heavy yield losses or entire crop failure as a result of severe insect pest attacks [3]
To achieve the objective of this study, two separate experiments were conducted. e first experiment examined the stability of the resistance in five cowpea cultivars/genotypes to aphid infestation. e second assessed the yield losses due to aphid infestation in a range of cultivars/genotypes including a cowpea cultivar that was crossed with a resistant genotype to improve its resistance to the pest
Summary
Cowpea (Vigna unguiculata (L.) Walp) is mostly cultivated in tropical Africa, and its edible seeds constitute a major source of protein [1]. One of the major constraints in the production of cowpea in Africa is severe infestation and damage by various insect pests in the field [2]. Us, it is prone to heavy yield losses or entire crop failure as a result of severe insect pest attacks [3]. Several insect pests attack all growth stages of cowpea, but their economic importance is highly dependent on the environment [4, 5]. E pest status of the different insects may vary from one country or region to another, but the losses reported suggest that any one major pest of cowpea can cause significant economic loss if not managed [5, 6] Others are the cosmopolitan green stink bugs, Nezara viridula and Piezodorus guildinii (Hemiptera: Pentatomidae); these are of minor economic importance. e pest status of the different insects may vary from one country or region to another, but the losses reported suggest that any one major pest of cowpea can cause significant economic loss if not managed [5, 6]
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
