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Field studies were conducted to investigate insect pests’ densities in intraspecies mixture of genotypically different soybean (Glycine max) cultivars and its effect on grain yield. Three soybean cultivars, Afayak, Jenguma and Favour, were sown in combinations comprising sole plantings of each cultivars, uniform mixtures of two different cultivars and mixtures of all 3 cultivars in equal quantities. In all there were 7 treatments. Insect pests recorded were defoliators, vegetative stage sucking insects and pod-sucking bugs (PSBs). The densities of defoliators and PSBs were higher in single cultivar plots than in those with at least two cultivars. Pest densities were similar between plots planted with two cultivars and those with a mixture of three. Grain damage was low when at least two cultivars were combined compared to sole crops. Consequently, grain yields in sole cultivars were lower than in those consisting of a mixture of at least two cultivars. Mixtures of genotypically different cultivars can therefore be used to manage defoliators and PSBs, consequently increasing yield.

Insecticide application is the recommended practice for control of insect pests on cowpea (Vigna unquiculata (L) Walp). However, these have negative effects on humans and the environment, apart from being costly for resource-poor farmers. This study aimed at identifying appropriate combinations of cultivar and insecticide spraying times for the management of economically important insect pests of cowpea in northern Ghana. The study was conducted in two successive rainy seasons at two locations situated in the Sudan and Guinea Savannah zones of northern Ghana. The experimental layout was a complete randomized split plot design with main-plots consisting of different numbers and timing of insecticide application and sub-plots consisting of 6 different cowpea cultivars. Data collected included insect pest abundances, components of yield and yield. Thrips (Megalurothrips sjostedti Trybom), legume pod borer (Maruca vitrata Fabricius) and a complex of pod-sucking bugs (PSBs) were the dominant insect pests. Their abundance and damage were not significantly different between the untreated control and cowpea sprayed once at 50% flowering stage. In contrast, protecting cowpea with either two (i.e., flower bud initiation and early podding) or three rounds of insecticide sprays (i.e., bud initiation, 50% flowering and 50% podding) significantly lowered insect pest abundance and increased grain yield. Apart from the farmer's cultivar which was susceptible to pest attacks, the improved ones showed variable levels of tolerance to the different pest categories. Combining at least two rounds of insecticide sprays with any improved variety suppressed pest populations and increase cowpea grain yield. Keywords: Cowpea, Insecticide treatments, Savannahs, Yield, Damage levels, Integrated pest management

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.

Fall armyworm (FAW), Spodoptera frugiperda (J.E. Smith), was first detected in Africa in 2016. Efforts at controlling it have been challenged by the many unknowns about this invasive insect. The population dynamics of FAW moths and the damage caused by the larvae were studied in maize fields over two successive seasons in northern Ghana. Pheromone traps were deployed in sole maize fields located in Northern (NR), Upper East (UER) and Upper West (UWR) regions to assess male moth population over time. Data on damage to maize by the larvae as well as climatic variables were also recorded. A total of 2601 FAW moths were captured over the two seasons from the three regions. In general, catches increased steadily from time of emergence (i.e., 12.2 ± 1.4 and 14.4 ± 2.6 moths in July 2017 and 2018, respectively) and peaked when the plants were growing into the reproductive stage (i.e., 13.9 ± 2.2 and 56.0 ± 14.9 moths in August 2017 and 2018, respectively); afterwards catches declined significantly. There were no significant differences between regions in both years for mean their moth catches. Damage to maize was significantly higher in 2017 (4.8 ± 0.4) than in 2018 (2.4 ± 0.3) (P = 0.005). This variable correlated positively with FAW larval abundance. Rainfall was the only climatic variable that influenced moth abundance significantly and positively in all three regions in both years; except for 2018 in UER. Thus, management of FAW in northern Ghana and locations with similar agro-ecologies must be from emergence to the tasselling stage, as well as periods of increased precipitation.

Aflatoxins contamination in peanut seeds remains a major challenge in Ghana. This study evaluated aflatoxin levels in peanut samples from farmer storage units, and participatory on-farm research trials. In all, 240 respondents were covered from six main producing districts in northern Ghana through a multi-stage sampling approach. Samples were analysed for total aflatoxins using the indirect Enzyme Linked Immunosorbent Assay technique. Overall, total aflatoxins in the farmer stored nuts showed wide variations across communities and districts. At 20 ppm permissible level, 92.9% of samples (n = 240) from farmer stored peanuts and 98.7% of samples (n = 150) from the on-farm demonstrations were classified as safe at 4–8 weeks after harvest. Therefore, sustainable reduction of aflatoxins to safe limits is possible through greater collaboration among the value chain actors. Low-cost good agricultural practices within the remit of the growers should be prioritized alongside public awareness programmes.