http://hdl.handle.net/123456789/6 2026-09-04T19:33:54Z http://hdl.handle.net/123456789/19836 An analytic and numerical study of a population density- dependent migration of a predator-prey system Chesang Symon, Adu. A.M.Wasike,H.Makwata andS. Muthiga We formulate a population-density-dependent migration of a predator and prey between two patches. The migration is influenced by prey and predator densities such that when the predator population is huge, the migration of prey population is more likely to occur. We also assume that migration is dependent on factors other than predation. Each patch display a limit cycle behaviour of the predator and prey interaction. Migration is on a fast timescale as compared to the inter-species interaction within a patch, thus we reduce the system from four ordinary differential equation to two by aggregation. Furthermore, we non- dimensionalize the aggregated model to reduce the number of parameters for ease of analysis. The analysis of the aggregated model shows three fixed points. Two are unstable, the third where there is co-existence of both species, its instability or stability is parameterdependent. For some certain parameter values, we get a limit cycle. This limit cycle is a synchronous state, that is observable in both patches. Key words: Aggregation; Non-dimensionalization; Limit cycle; Synchronization Mathematics Subject classification(2020): 34D25, 34D20, 37N 2025-01-01T00:00:00Z http://hdl.handle.net/123456789/19835 Modeling multifunctional landscape change in southern Kenya: Spatial trade-offs and drivers in an arid and semi-arid landscape Susan M. Kotikot a, * , Erica A.H. Smithwick a,b , Sarah E. Gergel c , Jedidah Nankaya d , Romulus Abila Arid and Semi-Arid Landscapes (ASALs) support a substantial portion of the world's population and multiple ecological and social functions. However, landcover outcomes in ASALs are determined by competing land uses, which are governed by fine gradients in biophysical conditions, legacy land use policies, and complex socio- economic drivers. Simulating these land use and land cover (LULC) interactions can promote policy that en- hances human and ecosystem well-being but capturing dynamics at scales relevant to local livelihoods remains challenging. To explore these interactions, we used the Land Change Modeler (LCM) to simulate spatial patterns of LULC change from 2010 to 2018 in a multifunctional landscape in southern Kenya. Results showed that spatial patterns of LULC transition were associated with biophysical and socio-political factors such as proximity to existing land use types, rainfall and temperature, and land tenure arrangements. Our calibrated model achieved 83% overall correctness, with remaining errors (17%) linked to spatial misallocation. These errors were spatially clustered, suggesting the possible influence of localized socioeconomic factors not included in our parameteri- zation. Notably, transitions in humid–arid ecotones were consistently underestimated, reflecting the challenges of capturing fine-scale heterogeneity in ecologically sensitive landscapes. Our findings demonstrate where conservation objectives, agricultural expansion, and pastoral livelihoods spatially converge, highlighting land- scape zones where policy interventions and development investments are most likely to generate trade-offs rather than synergies under increasing climate stress. These results underscore the value of spatially explicit modeling as a diagnostic tool for identifying priority areas where competing land-use demands and socio- ecological vulnerabilities are most tightly coupled. 2026-01-01T00:00:00Z http://hdl.handle.net/123456789/19834 Sperm-disrupting activity of a root bark fraction of Flueggea virosa (Roxb. ex willd.) royle uncovered using LC-MS/MS profiling and functional evaluation Kehongo M. Nyanguru, Caroline Maina, Mutiat Ibrahim, James Kuria, Ephantus Ndirangu, Sospeter Ngoci Njeru, Abdullahi Abdulraheem, Edwin Murungi, Moses Obimbo, Adeyemi O. Aremu, Aloys Mosima Osano, Samwel Cheruiyot, Margaret O. Ilomuanya, Peter Waweru Mwangi, Elizabeth Kigondu Introduction: While Flueggea virosa (Roxb. Ex Willd.) Royle root bark is traditionally used in several parts of East Africa for fertility regulation, its contraceptive potential has not been systematically investigated. Given the paucity of safe, reversible, non-hormonal contraceptives for women, this study evaluated a root bark fraction for sperm-disrupting, intravaginal contraceptive activity using functional assays and a rabbit proof-of-concept model. Methods: Following extraction and fractionation of authenticated root bark, the resulting extracts were evaluated for cytotoxicity in Vero cells and for disruption of human sperm functions by ascertaining immobilization, revival, viability, cervical mucus penetration and acrosin-related activity. Thereafter, chemical profiling of the most active fraction was performed using liquid chromatography-tandem mass spectrometry (LC-MS/MS) for descriptive annotation. Moreover, in vivo contraceptive efficacy and short-term local safety (10 days) were determined after intravaginal administration of the fraction in rabbits by histological examination of cervicovaginal tissues. Results: The methanolic fraction (KBLM) demonstrated the strongest activity, completely immobilizing sperm, abolishing sperm revival after washing, markedly reducing sperm viability, strongly inhibiting cervical mucus penetration and suppressing acrosin-related activity at 1.62 mg/mL. In a rabbit proof-ofconcept experiment, a single intravaginal dose prevented pregnancy at all tested concentrations (3.9, 7.8, and 15.6 mg/mL). Besides, repeated OPEN ACCESS EDITED BY Maša Knez Marevci, University of Maribor, Slovenia REVIEWED BY Tushar Dhanani, Florida Agricultural and Mechanical University, United States Parasuraman S, AIMST University, Malaysia *CORRESPONDENCE Kehongo M. Nyanguru, kehongo@mmarau.ac.ke, kehongomoses1995@gmail.com Elizabeth Kigondu, m_kigondu@yahoo.com, ekigondu@kemri.go.ke RECEIVED 20 March 2026 REVISED 11 June 2026 ACCEPTED 15 June 2026 PUBLISHED 01 July 2026 CITATION Nyanguru KM, Maina C, Ibrahim M, Kuria J, Ndirangu E, Njeru SN, Abdulraheem A, Murungi E, Obimbo M, Aremu AO, Osano AM, Cheruiyot S, Ilomuanya MO, Mwangi PW and Kigondu E (2026) Spermdisrupting activity of a root bark fraction of Flueggea virosa (Roxb. ex willd.) royle uncovered using LC-MS/MS profiling and functional evaluation. Front. Pharmacol. 17:1835308. doi: 10.3389/fphar.2026.1835308 COPYRIGHT © 2026 Nyanguru, Maina, Ibrahim, Kuria, Ndirangu, Njeru, Abdulraheem, Murungi, Obimbo, Aremu, Osano, Cheruiyot, Ilomuanya, Mwangi and Kigondu. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Frontiers in Pharmacology 01 frontiersin.org intravaginal exposure for 10 days revealed absent-to-mild cervicovaginal changes. Chemical fingerprinting putatively annotated flavonoid-, tannin-, and phenolicrelated features, including catechin, quercetin derivatives, rutin, corilagin, and kaempferol glycosides, as prominent features of KBLM. Conclusion: Our findings have demonstrated the sperm disruption activity of the methanolic fraction of F. virosa root bark. The observed disruption of multiple sperm functions, observed efficacy in a rabbit model and absent-to-mild shortterm local tissue changes support additional preclinical investigations of the extract geared towards further functional characterization, extended safety testing, standardization, and potential formulation of an intravaginal contraceptive. 2026-07-01T00:00:00Z http://hdl.handle.net/123456789/19833 Effects of forest degradation on bats at the South and North Nandi Forests, Western Kenya Sospeter Kibiwot, Millicent J. Bungei, Johnstone Kimanzi, David B. Wechuli, Paul W. Webala Habitat loss and degradation pose significant threats to biodiversity, especially in tropical regions characterized by high biodiversity levels and elevated deforestation rates. However, there is a lack of sufficient information concerning the effects of such disturbances on bats (Mammalia: Chiroptera) in tropical Africa. This research investigated the impact of habitat degradation on bat communities in two forests of varying sizes, South Nandi and North Nandi, located in western Kenya, through bat capture methods. Tree density and forest human use intensity served as predictors for relative bat abundance and species richness. A total of 6,003 bats were recorded, representing 21 species across seven families, during a comprehensive study involving 5,322 hours of mist-netting and 4,224 hours of harp trapping. A progressive decline in species richness (S) was observed from the forest interiors (S = 17) to the edges (S = 16) and the matrices (S = 12) at both forests. Fruit bats (n = 3427; 61.7%) were predominantly detected at the edges and within the matrices, with a limited presence in the forest interior. Conversely, forest-interior insectivorous bats and those foraging in confined spaces (n = 260; 58.6%) were primarily recorded within the forest interiors. Forest specialists exhibited significant correlations with tree density, whereas frugivores and edge- and open-space foraging species showed positive responses to human activity indicators, including cut stumps, charcoal kilns, and footpaths in highly degraded matrices and along forest edges. Consequently, specialized bat species are particularly vulnerable to habitat loss and degradation. 2026-06-01T00:00:00Z