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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

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.