High populations of species in the whitefly complex Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) were reported to cause severe damage to cassava in East and Central Africa. However, reasons for B. tabaci population increases are not well understood. We investigated the effect of cassava morphological traits, temperature, rainfall and relative humidity (RH) on the abundance of B. tabaci. Five cassava genotypes with varying levels of resistance to cassava mosaic disease, cassava brown streak disease, and B. tabaci infestation were planted in three Ugandan agro-ecological zones. The experiment was conducted in 2016 and 2017 in a randomized complete block design. Across all locations, the tallest genotype Alado alado supported the lowest number of B. tabaci adults. In areas with high B. tabaci prevalence, leaf area, leaf lobe width, and leaf lobe number exhibited significant positive effects (p < 0.001) on B. tabaci adult count. Positive effects of relative humidity and negative effects of temperature and rainfall on B. tabaci adult and nymph counts were observed in 2016 and 2017, resulting in low populations in Lira. Evidently, temperatures of 28–30 °C, rainfall of 30–150 mm and RH of 55–70%, and deployment of cassava genotypes of low plant height, large leaf area, and lobe width significantly enhanced B. tabaci population growth.

Encarsia sophia Girault and Dodd and Eretmocerus mundus Mercet (Hymenoptera: Aphelinidae) are important biological control agents of Bemisia tabaci Gennadius (Hemiptera: Aleyrodidae) because of their outstanding parasitic and destructive host-feeding ability. This study evaluated their parasitism and host-feeding capacity at five B. tabaci SSA1 host densities (10, 40, 60, 100 and 140) on three cassava genotypes (Alado alado, NAROCASS 1 and NASE 14) in the screenhouse. The results revealed that host density and parasitoid species had significant effects (P < 0.001) on host feeding and parasitism of B. tabaci SSA1, while cassava genotype had no effect (P > 0.05). Both E. mundus and E. sophia females killed more hosts by parasitism and host feeding with increased host density; E. mundus parasitised 1.5 and 40.2 nymphs at host density of 10 and 140 nymphs, respectively. At all host densities, E. sophia killed more hosts by feeding while E. mundus parasitised more hosts. However, E. mundus caused more total nymph death than E. sophia at all host densities. At a host density of 100 nymphs, E. mundus killed 38.9 nymphs compared to the 22.4 nymphs killed by E. sophia. In conclusion, the two parasitoids had a density-dependent relationship with the host, irrespective of species which bodes well for biological control programs. Thus, the deployment of these hymenopteran parasitoids in areas with high B. tabaci SSA1 populations through augmentative release would offer commendable pest population suppression. The interaction of cassava genotype with parasitoid species improved biocontrol efficiency, hence as long as a glabrous cassava genotype is planted, efficacy is enhanced.

Natural death is a key determinant of a species population dynamics. Thus, a clear understanding of natural mortality factors aids the development of appropriate management strategies for insect pests. Cohort-based life tables were constructed to determine the sources and rates of mortality of field populations of the pest, Bemisia tabaci Sub-Saharan Africa 1 (SSA1) on cassava in Uganda. Monthly cohorts (10 in total) were established separately for eggs and nymphs on two cassava genotypes with known levels of resistance to B. tabaci infestation (Alado alado and NAROCASS 1). Mortality was recorded using daily observations for the eggs and the different nymphal instars. The recorded mortality sources were disappearance (total removal of egg or nymph from the leaf), predation, parasitism (nymphs only), unknown death and inviability (eggs only). Median marginal mortality rate was highest for disappearance (0.355) followed by parasitism (0.058). The highest level of mortality occurred during the third nymph stage (55% on Alado alado) and only 12% of nymphs reached the adult stage. Irreplaceable mortality (Ic) was highest for disappearance followed by third instar parasitism. Key-factor analysis revealed a close resemblance of the curve for disappearance to that of total mortality coupled with the highest regression slopes: 0.896 for eggs and 0.725 for nymphs on NAROCASS 1. From these results, we conclude that disappearance and parasitism are the major mortality factors controlling B. tabaci SSA1 populations. Therefore, the development of interventions that focus on enhancing the levels of disappearance and third instar parasitism may lead to population-level reductions in B. tabaci SSA1. Further studies need to be conducted to understand the factors that contribute to the high mortality associated with disappearance.

The invasive weed Parthenium hysterophorus L. presents a severe socio‐economic threat to Ugandan agriculture. This nationwide study of 244 farmers in infested districts reveals near‐universal recognition of the weed and widespread negative impacts: 88.3% of the farmers report increased labour demands, 62.1% cite yield reduction and significant costs are incurred through control efforts and degradation of soil and pasture resources. A multivariate probit analysis shows that most farmers rely on single‐method strategies. Hand weeding (76.7%) is the predominant practice and is driven by labour challenges, while herbicide use (6.7%) is associated with concerns over product quality and soil degradation. Machine weeding (45.8%) substitutes for manual labour and is influenced by region, cropping system and soil health perceptions. Critically, practices are not used in complementary combinations. The findings underscore an urgent need for context‐specific extension programmes to promote Integrated Weed Management that builds upon existing farmer practices to mitigate this livelihood crisis.

Kariba weed (Salvinia molesta D.S. Mitch.) is a floating aquatic fern that has devastated aquatic production systems worldwide. The objective of this study was to establish the status of occurrence and infestations levels of the weed on the water bodies in Uganda. The study was conducted on purposefully selected water bodies in Uganda, over a period of 2018 to 2022. Kariba weed occurred at varying infestation levels on all water bodies in the country, except on Lake Bisina. The highest number of daughter plants (732 plants per 0.25 m2 quadrant) was registered at Kajjansi, along Lake Victoria. The main impacts of the weed on the water bodies were obstruction of fishing and water transport; and reduced water quality. Given that Kariba weed is dispersed by water currents and vegetatively spread by boats and fishing gears, a catasptrophe in terms of dysfunction of the productivity of the country’s water resources is eminent. Biological control of Kariba weed using Cyrtobagous salviniae weevils is recommended to sustainably manage this devastating water weed.