Kowiyou Yessoufou

Insect herbivory plays a critical role in shaping plant growth, fitness, and population dynamics, yet its effects across African ecosystems remain poorly understood due to fragmented, methodologically diverse, and geographically biassed research. To address this gap, we conducted an integrated bibliometric and systematic review of peer-reviewed studies on insect herbivory and plant performance in Africa. Searches of Web of Science and Scopus identified 1642 records, of which 312 met relevance criteria and 157 satisfied quality thresholds, including clear herbivory metrics and robust experimental or observational designs. Bibliometric analyses revealed modest but increasing publication rates, with research concentrated in Southern and Eastern Africa and primarily focused on savannas and agroecosystems. Montane forests, wetlands, and arid ecosystems remain underrepresented. Most studies examined Lepidopteran leaf herbivory, while fewer than 15% addressed root, stem, or seed damage, and research collaborations were largely regional. Systematic synthesis showed that insect herbivory generally reduces seedling survival, height, and biomass, particularly at early life stages, although some species display tolerance or compensatory growth depending on environmental conditions and plant traits. Reported effect sizes were highly variable (Hedges’ g = 2.1–3.4), reflecting differences in ecological context, herbivore guilds, and study design. Few studies incorporated multiple life stages, trophic interactions, or climate gradients, limiting inference on long-term population and ecosystem responses. We emphasise the need for harmonised methodologies, trait-based and guild-specific approaches, long-term manipulative studies, and expanded research across underrepresented ecosystems to better inform conservation and restoration under environmental change.

Summary: Although cities are increasingly recognized as ecological islands, a unified framework explaining their susceptibility to alien plant invasion remains lacking. Using the most recent and comprehensive global dataset of urban alien plants, we modelled alien richness, mimicking island biogeography theory (IBT). Across all models, neither city size nor geographic isolation independently explained alien richness. Instead, richness was consistently associated with their interaction, supporting the central IBT prediction. However, the strength of this interaction depends on how city size was quantified, with socio-economic dimensions exhibiting stronger positive interactions with geographic isolation than physical measures of city size. Introduction-hub identity further modified these relationships. North America was the only hub for which the interaction between city size and isolation was consistently weakened, indicating that donor regions of alien plants are not ecologically equivalent. Simulations of simultaneous increases in city size and isolation showed that larger, more connected cities generally accumulated more alien plants despite increasing geographic distance, but the magnitude and direction of these responses are hub dependent. Our findings inspire an extension of classical IBT to a mechanistic explanation for global variation in urban alien plant richness in this increasingly urbanized and globally connected world. Graphical abstract (drawn using AI): The Urban Island Biogeography Framework (UIBF) extends classical Island Biogeography Theory to explain global patterns of alien plant richness in cities. Across six measures of urban size, neither city size nor geographic isolation independently predicted alien richness; instead, their interaction consistently explained invasion patterns. Socio-economic dimensions of urbanization (population size and GDP) strengthened this interaction more than physical city attributes, highlighting the importance of anthropogenic connectivity. Introduction-hub identity further modified these relationships, with Washington uniquely weakening the positive interaction between urban size and isolation. Together, these findings provide a mechanistic framework for predicting urban biological invasions in an increasingly connected world.

Urban Heat Island (UHI) effects are increasingly acknowledged as a critical urban climate challenge with far-reaching consequences for human health and overall well-being. However, the conceptual structure, temporal evolution, and intellectual landscape of studies examining the relationships between UHI and human well-being remain fragmented, thereby constraining the development of integrated knowledge frameworks needed to guide future research, urban adaptation strategies, and evidence-based policy interventions. To this end, a total of 4857 studies were retrieved from the Scopus and Web of Science databases and screened following the PRISMA guidelines. These studies were then analyzed using Bibliometrix and VOSviewer. The results reveal a rapid and exponential growth in scientific output, particularly after 2010, with the output reaching its highest level in recent years. These outputs were shaped mostly in China and the United States with a well-established international collaboration network, while the Global South remain significantly underrepresented in scientific productions. We also found that studies are primarily structured around four dominant research clusters: urban heat island, thermal comfort, land surface temperature, and climate change. Furthermore, early studies predominantly focused on urban surface properties and built-environment characteristics, while recent research has increasingly shifted toward human health impacts, thermal stress, heat vulnerability, and well-being. Emerging research directions further highlight growing interest in nature-based solutions for mitigating UHI effects, alongside the application of advanced technologies such as machine learning and remote sensing for high-resolution urban climate assessment. Overall, our findings indicate a transition toward a more integrated urban climate–health–well-being research framework, while simultaneously revealing persistent geographical and conceptual gaps, particularly across the Global South. We therefore advocate for increased empirical research, stronger international collaboration, and context-specific urban adaptation strategies to better safeguard human well-being under intensifying urban heat conditions.

Understanding why some plants experience greater herbivory than others is central to predicting population dynamics and ecosystem resilience. We tested the plant vigour hypothesis, the resource concentration hypothesis and the role of anthropogenic disturbance in shaping herbivory of a heavily harvested medicinal plant in South Africa. Plant height and canopy size were positively associated, indicating coordinated growth, yet these traits responded differently to environmental gradients: Larger canopies were more common at higher elevations and closer to human settlements, whereas taller plants occurred at lower elevations and farther from settlements. Root harvesting was negatively size‐dependent, with taller individuals harvested less intensively; however, harvesting pressure increased significantly at lower elevations and near settlements, reflecting strong disturbance effects. Insect herbivory increased with harvesting intensity but was unrelated to plant vigour, providing little support for the plant vigour hypothesis in this system. We suggest that anthropogenic pressures may increase herbivory through multiple pathways, including increased plant exposure following disturbance, stress‐induced reductions in plant defence and potential disruption of plant–insect dynamics. Cumulatively, our findings show that herbivory risk is structured more strongly by anthropogenic disturbance and spatial environmental gradients than by intrinsic plant vigour, highlighting the interactive roles of ecological and human drivers in shaping plant–insect dynamics.

The Doctrine of signature suggests there are parallels between a plant's appearance, structure, or therapeutic functions that it may have on the corporal systems of the human body as well as the disease it treats. This concept, often considered more of a traditional belief than an established scientific theory has been dismissed as primitive and unscientific or as a mnemonic aid. However, direct tests of these theoretical predictions are rare, suggesting most of these criticisms are premature. We tested one of the most popular doctrine of signatures that red sap plants treat blood disorders. We systematically reviewed the literature for a comprehensive list of red sap-containing plant species across the world, randomly selected 200 other plant species without red sap in the same regions, and recorded the medicinal uses of all species. We demonstrate that species containing red sap were three times more likely to be used in the treatment of blood-related disorders. In addition, similarly to plant species used in the treatment of blood disorders, species with red sap were also phylogenetically close. This strong relationship is most likely due to red quinones often present in plants with red sap which are known for their efficacy in wound healing. Our straightforward approach can be used by ethnobiologists for more tests of other doctrines of signatures. It is important to establish a mechanistic understanding of the links between signature, plant secondary chemistry, and therapeutic efficacy.

Universal electricity access remains elusive in Lesotho, with only a 53% connection rate. This statistic highlights a significant urban–rural gap of 60% to 18%, favouring urban areas mainly served by the main grid. The rugged terrain renders extending the grid to most rural areas impractical. To address this, the energy policy and electrification master plans aim to leverage abundant renewable energy resources and deploy mini-grids in rural regions. However, progress has been slow since the first advanced mini-grid projects began in 2018. The paper reviewed policy and framework documents from 2010 to 2025 that are pertinent to the deployment of mini-grids. It employed a hybrid qualitative-quantitative approach of SWOT-TOWS-AHP, which is rarely applied in energy policy analysis. It used the SWOT analysis tool to identify the Strengths, Weaknesses, Opportunities, and Threats faced in implementing sustainable renewable energy mini-grids. This was followed by the TOWS-AHP (Threats, Opportunities, Weaknesses, and Strengths-Analytical Hierarchy Process) method to develop strategies that utilize strengths and seize opportunities while tackling weaknesses and mitigating threats. These strategies were ranked based on their potential impact on mini-grid deployment. Despite supporting policies for mini-grids, the lack of political will from the government has emerged as a major obstacle. The three top strategies suggested to accelerate the deployment of sustainable mini-grids and advance efforts to achieve Sustainable Development Goal no. 7 by 2030 are establishing a mini-grid financing fund, reviewing the mini-grid regulatory framework, and reforming rural electrification institutions to improve coordination and collaboration. The top strategies carry weights of 8.5%, 7.8%, and 7.7%, respectively.

Environmental crime is becoming a significant developmental and regulatory challenge, especially in developing regions. The increasing prevalence of wildlife theft, land and atmospheric pollution, and illegal mining, among others, has severe impacts on the economic and the sustainability of social and environmental ecosystems. Against this backdrop, this study aimed to analyse the spatial and temporal dynamics of environmental crime in South Africa to inform preventative and remedial actions. We collected time-series data from the Department of Forestry, Fisheries, and the Environment (DFFE) on the occurrence of environmental crime, classified into brown, green, and blue types, from 2017 to 2019. Our results show increasing trends in the occurrence of brown crimes, and a stable occurrence of green and blue crimes. Furthermore, the occurrence of environmental crimes is concentrated in the economic hubs of the country, such as the Gauteng and Western Cape provinces. It is envisaged that these results will aid the enhancement of environmental crime monitoring and law enforcement in the country.

Existing studies report that medicinal plants are either phylogenetically clustered or that plant medicinal property is phylogenetically conserved. Each scenario is traditionally interpreted as evidence of non-random selection by humans of medicinal plants. Here, we argue that this interpretation is misleading, highlighting that both scenarios are simultaneously required for a correct interpretation of human selection of medicinal plants. We propose a framework to illustrate all possible scenarios of phylogenetic patterns and human selection options and tested the framework employing phylogenetic comparative methods on medicinal plant data collected in northern Nigeria. First, we found a mixed selection pattern in plant organs used for medicine, perhaps mirroring the within-plants heterogeneous distribution of secondary compounds as predicted in the optimal defense theory. Second, medicinal plants used to treat most diseases follow a random distribution on the phylogeny, whereas their medicinal properties are convergent on the phylogeny. This pattern is plausible only when humans select preferentially less related species for medicinal uses. That we found a random phylogenetic structure for species used to treat most diseases would, traditionally, have been interpreted as random selection of medicinal plants. We, therefore, call for caution while interpreting phylogenetic patterns in ethnobiology.