Invasive alien species pose a serious threat to the world’s ecosystems and livelihoods. This review aimed to investigate the negative and positive impacts of Prosopis juliflora (Sw.) DC on ecosystems in Kenya and Ethiopia. The bibliographic analysis highlighted that Prosopis juliflora was introduced to Kenya and Ethiopia to tackle desertification, ensure the self-sufficiency of wood products, and conserve water and soil in semi-arid areas. Years later, this species has turned invasive; although the communities in infested areas have realized some benefits from this tree such as obtaining timber, charcoal, firewood, shelter, and livestock feed from its pods; the negative impacts of this tree have far outweighed the positives. Notably, this invasive plant has significantly impacted agricultural and livestock productivity by invading pasturelands and farmlands. For instance, the negative health implications for livestock significantly reduce their productivity. Similarly, this plant has reduced the diversity of the native trees, herbaceous, and grasses because of its ability to outcompete them. Control methods such as biological, mechanical, chemical, and control by utilization have been tried but none have so far been effective in controlling this invasive plant. Our results showed that Prosopis juliflora is a serious invader that has a huge potential to invade the arid and semi-arid lands of Kenya and Ethiopia. Therefore, stakeholders at all levels need to implement integrated management strategies to reduce the spread and the negative impacts of this species.

The Fall armyworm (FAW), Spodoptera frugiperda (J. E. Smith) invaded sub-Saharan Africa (SSA) in 2016 and has since become prevalent in many countries, causing significant maize grain yield losses and reduced grain quality. Breeding for host plant resistance to FAW requires improving multiple traits, complicating selection. This study evaluated the use of principal component (PC)-based multi-trait selection indices to identify FAW resistant maize genotypes. A total of 192 maize hybrids alongside four commercial hybrids, were evaluated over four seasons under artificial FAW infestation. Data on FAW leaf feeding damage (LD) at 7, 14, and 21 days after infestation, and ear damage (ED), ear rot (ER), and grain yield (GY) were recorded. The data were subjected to analysis of variance and PC analysis, and results used to construct two economic weight-free selection indices: PC1-based index (PC1BI) and PC2-based index (PC2BI). Broad-sense heritability estimates were 0.59 to 0.73 for LD, and 0.69 for GY. The two PCs explained 97.1% of the variation among the hybrids. PC1BI, with higher loadings for the leaf feeding damage traits, showed the larger desired gains for these traits (−2.92 to −3.84%) and GY (19.9%), making it a superior index to PC2BI. PC1BI identified six promising hybrids with GY above the cutoff of 7.0 t ha^-1 for selection under FAW infestation. PC2BI exhibited larger gains for ED (−11.1%) and ER (−45.4%). The index-based selected hybrids consistently outperformed the commercial hybrid checks. The PC-based indices have the potential to serve as valuable tools for breeders to maximize selection gains; however, modifications are necessary to incorporate other desirable agronomic and adaptive traits.

The study was conducted to; validate the genotypic performance of the popular climate-smart released maize varieties under increased plant densities in the three sub-ecologies (Mid-altitude, semi-arid, and tropical rain forest zones), which are important maize crop production belts and testing sites for new hybrids, and estimate the profitability of growing the varieties under optimum plant density in the different sub-ecologies. Seven popular varieties; MM3, Longe 6H, Longe 9H, Longe 10H, Bazooka, WE 3106, and FH5160 were tested for two seasons at four different spacing levels: 0.75 × 0.6 M (44,444 plants ha-1), 0.75 × 0.30 M (44,444 plants ha-1), 0.75 × 0.25 M (53,333 plants ha-1), and 0.5 × 0.3 M (66,667 plants ha-1). The varieties varied significantly for grain yield (GY) and ear aspect (EA) traits across the spacings and environments. Using the closest spacing (0.50 × 0.30 M) resulted in higher GY productivity and net profit in the testing sites. At optimal spacing, FH5160 was the most stable genotype for cultivation across the three sub-ecologies. All varieties exhibited superior genotypic performance for GY (7-12 t ha-1) and EA traits in the mid-altitude zone. Bazooka and Longe 10H were the best varieties for the tropical rainforest zone. While MM3, WE3106 and Bazooka were more suitable for semi-arid zone. Growing all the studied maize varieties in the mid-altitude sub-ecological zone is profitable, especially at optimal spacing.