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Fall armyworm (FAW), Spodoptera frugiperda (Smith) (Lepidoptera: Noctuidae), invasion in Africa has threatened food security. Optimization of plant tolerance and post-infestation recovery are among the management tactics that are being promoted for the integrated management of this pest, but these techniques are poorly studied in sub-Saharan Africa. Our study examined the efficacy of enriched compost, split-NPK fertilization, conventional fertilization, and bioinsecticides on FAW infestation rates, maize plant resilience, natural enemy presence, and grain yield. We found that split-NPK fertilization significantly improved maize plant robustness and reduced FAW incidence and leaf damage in a phenology-dependent manner, leading to higher grain yields. A synergistic effect was observed when split-NPK was coupled with bioinsecticides, resulting in increased populations of natural predators, and specifically the egg endoparasitoid, Telenomus remus (Nixon) (Hymenoptera: Scelionidae). Multivariate analyses confirmed that factors like split-NPK fertilization, bioinsecticide usage, stem circumference, and overall plant robustness are major determinants of maize grain yield. Our results endorse soil fertility management via split-NPK fertilization as an effective cultural control measure against FAW, providing an alternative to synthetic insecticides. These insights set the stage for future research focused on assessing the economic viability of this integrated approach, exploring the integration of split-NPK with alternative insecticides, evaluating environmental impacts, and examining the underlying resilience mechanisms to FAW, among other avenues. • Split-NPK fertilization significantly reduced Fall Armyworm (FAW) incidence and leaf damage. • Combined usage of split-NPK fertilization and bioinsecticides favored the recruitment of natural ennemies, especially egg parasitoid, Telenomus remus. • Higherst maize grain yields were obtained with the split-NPK fertilization model regardless of bioinsecticide use. • Split-NPK, bioinsecticides, and plant robustness are key determinants of maize grain yield. • These findings support the use of split-NPK fertilization and bioinsecticides as an integrated pest management (IPM) strategy against FAW. [ABSTRACT FROM AUTHOR]

The fall armyworm Spodoptera frugiperda (J. E. Smith) invaded several West African countries in 2016 causing severe injury to maize plants and economic damage. This study assesses variations in the occurrence of this species in different Agro-Ecological Zones (AEZs) in Togo and Ghana during the 3 yr following its discovery. The surveys were conducted on 120 farms in Togo and 94 farms in Ghana by collecting larvae from 200 maize plants per hectare. Infestation levels were 68.46% in 2016, 55.82% in 2017, and 17.76% in 2018. The number of larvae recorded per hectare and infestation levels were higher in Togo than in Ghana. The lowest number of collected larvae and infestation levels of S. frugiperda were in 2018, compared to the other 2 yr. Larvae per hectare and the infestation level varied regionally inside the two countries. The southern part of Togo (AEZ five) contained higher numbers of larvae and higher infestation levels during the 2 yr following the invasion of the pest. We concluded that infestation levels of S. frugiperda are much lower in 2018 than the two previous years and it is therefore necessary to determine the factors that affect the population dynamics of S. frugiperda in the field, which is a perquisite for developing management interventions. [ABSTRACT FROM AUTHOR]

Simple Summary: The fall armyworm (FAW) is a serious threat to maize production in Africa following its outbreak in 2016. Fortunately, some beneficial insects that could control FAW are already present in Africa, including Telenomus remus which parasitizes FAW eggs. Telenomus remus has been used in South America for biological control of FAW for several decades. Though T. remus is already present in Africa, little is known about its potential to be used for augmentative biological control of FAW under ecological conditions and agricultural systems in Africa. This study contributed to addressing this knowledge gap by conducting replicated field release trials of T. remus for FAW control in large maize plots in Ghana. In the major and minor rainy seasons, T. remus parasitized up to 33% and 100% of FAW egg masses, respectively, in the release plots. However, similar effectiveness of T. remus was recorded in non-treated control and farmers' plots located at 150–400 m distance from release plots, indicating high dispersion of the parasitoid. A single application of Emamectin benzoate did not significantly affect the parasitism rates of T. remus, and could be considered in IPM strategies against FAW. In response to the threat caused by the fall armyworm to African maize farmers, we conducted a series of field release studies with the egg parasitoid Telenomus remus in Ghana. Three releases of ≈15,000 individuals each were conducted in maize plots of 0.5 ha each in the major and minor rainy seasons of 2020, and compared to no-release control plots as well as to farmer-managed plots with chemical pest control. No egg mass parasitism was observed directly before the first field release. Egg mass parasitism reached 33% in the T. remus release plot in the major rainy season, while 72–100% of egg masses were parasitized in the minor rainy season, during which pest densities were much lower. However, no significant difference in egg mass parasitism was found among the T. remus release plots, the no-release control plots and the farmer-managed plots. Similarly, no significant decrease in larval numbers or plant damage was found in the T. remus release fields compared to the no-release plots, while lower leaf and tassel damage was observed in farmer-managed plots. Larval parasitism due to other parasitoids reached 18–42% in the major rainy season but was significantly lower in the minor rainy season, with no significant differences among treatments. We did not observe significant differences in cob damage or yield among the three treatments. However, the lack of any significant differences between the release and no-release plots, which may be attributed to parasitoid dispersal during the five weeks of observation, would require further studies to confirm. Interestingly, a single application of Emamectin benzoate did not significantly affect the parasitism rates of T. remus and, thus, merits further investigation in the context of developing IPM strategies against FAW. [ABSTRACT FROM AUTHOR]