Reduced Population Densities Research Articles

Quinolone-mediated metabolic cross-feeding develops aluminium tolerance in soil microbial consortia

Aluminium (Al)-tolerant beneficial bacteria confer resistance to Al toxicity to crops in widely distributed acidic soils. However, the mechanism by which microbial consortia maintain Al tolerance under acid and Al toxicity stress remains unknown. Here, we demonstrate that a soil bacterial consortium composed of Rhodococcus erythropolis and Pseudomonas aeruginosa exhibit greater Al tolerance than either bacterium alone. P. aeruginosa releases the quorum sensing molecule 2-heptyl-1H-quinolin-4-one (HHQ), which is efficiently degraded by R. erythropolis. This degradation reduces population density limitations and further enhances the metabolic activity of P. aeruginosa under Al stress. Moreover, R. erythropolis converts HHQ into tryptophan, promoting the synthesis of peptidoglycan, a key component for cell wall stability, thereby improving the Al tolerance of R. erythropolis. This study reveals a metabolic cross-feeding mechanism that maintains microbial Al tolerance, offering insights for designing synthetic microbial consortia to sustain food security and sustainable agriculture in acidic soil regions.

Impact of Depopulation on Forest Fires in Spain: Primary School Distribution as a Potential Socioeconomic Indicator

Socioeconomic factors are increasingly considered in the study of forest fires. However, there is a gap in the literature on the possible relationship between basic services and infrastructures such as small rural schools and forest fires. Population decline in rural areas is leading to an increase in forest fire risk and social vulnerability to forest fires due to the abandonment of traditional agroforestry practices and the expansion of unmanaged forest canopy. In addition, rural schools are supposed to make rural municipalities livable and promote the people’s sense of community. In parallel, there is controversy over the closure of small local schools in sparsely populated rural areas worldwide. Our study identified that the forest area burned in the province of Avila (Central Spain), during the period 1996 to 2023, was higher in municipalities without rural primary schools. The presence of rural schools was as statistically significant as the influence of orographic variations of the territory, the number of incipient fires, and the reduction of population density during the same period. Our work contributes to highlighting the potential links between the decline of essential services in rural areas and the increase in forest fire risk, to urge policymakers to take a collaborative and holistic view.

Penerapan prosedur operasional standar budi daya tanaman jeruk ramah lingkungan untuk menekan infestasi kutu perisai merah Aonidiella aurantii (Maskell) (Hemiptera: Diaspididae)

Jeruk merupakan tanaman hortikultura yang sudah dikembangkan diberbagai daerah di Indonesia. Setiap tahun permintaan buah jeruk selalu meningkat, namun tidak terpenuhi karena produksi rendah. Permasalahan ini disebabkan oleh adanya serangan organisme penggangu tanaman, yaitu hama kutu perisai merah Aonidiella aurantii (Maskel). Upaya yang dilakukan untuk menekan infestasi A. aurantii, yaitu dengan penerapan prosedur operasional standar (SOP) pada budi daya tanaman jeruk ramah lingkungan. Tujuan penelitian ini adalah untuk mengetahui efektifitas penerapan SOP dalam menekan populasi dan intensitas serangan hama kutu perisai merah A. aurantii pada tanaman jeruk. Penelitian dilaksanakan bulan Januari sampai Agutus 2020 di kebun jeruk milik petani di Kota Batu. Penelitian eksperimen ini menggunakan metode teori research design. Perlakuan terdiri atas petak penerapan SOP berupa pemangkasan pemeliharaan, sanitasi kebun, dan aplikasi pupuk organik; dan petak konvensional kebiasaan petani yang tidak melakukan pemangkasan, membersihkan gulma di seluruh kebun, penggunaan pupuk anorganik NKP Mutiara 16-16-16. Luas setiap petak perlakuan adalah 1.500 m2. Pada setiap pelakuan diambil 10 tanaman sampel secara sistematik. Pengamatan setaiap tanaman dilakukan pada ranting atau cabang yang tersebar pada 4 arah mata angin. Pengamatan meliputi jumlah buah terserang, kelimpahan musuh alami, populasi, dan intensitas serangan A. aurantii. Hasil penelitian menunjukkan bahwa perlakuan penerapan SOP budi daya jeruk mampu menurunkan kepadatan populasi dan intensitas serangan hama A. aurantii secara nyata serta mampu meningkatkan kelimpahan musuh alami dan kualitas buah jeruk apabila dibandingkan dengan cara budi daya jeruk pada perlakuan konvensional.

Developing a transit desert interactive dashboard: Supervised modeling for forecasting transit deserts.

Transit deserts refer to regions with a gap in transit services, with the demand for transit exceeding the supply. This study goes beyond merely identifying transit deserts to suggest actionable solutions. Using a multi-class supervised machine learning framework, we analyzed factors leading to transit deserts, distinguishing demand by gender. Our focus was on peak-time periods. After assessing the Support Vector Machine, Decision Tree, Random Forest, and K-nearest Neighbor, we settled on the Random Forest method, supported by Diverse Counterfactual Explanation and SHapley Additive Explanation in our analysis. The ranking of feature importance in the trained Random Forest model revealed that factors such as density, design, distance to transit, diversity in the built environment, and sociodemographic characteristics significantly contribute to the classification of transit deserts. Diverse Counterfactual Explanation suggested that a reduction in population density and an increase in the proportion of green open spaces would likely facilitate the transformation of transit deserts into transit oases. SHapley Additive Explanation highlighted the differential impact of various features on each identified transit desert. Our analysis results indicate that identifying transit deserts can vary depending on whether the data is aggregated or separated by demographics. We found areas that have unique transit needs based on gender. The disparity in transit services was particularly pronounced for women. Our model pinpointed the core elements that define a transit desert. Broadly, to address transit deserts, strategies should prioritize the needs of disadvantaged groups and enhance the design and accessibility of transit in the built environment. Our research extends existing analyses of transit deserts by leveraging machine learning to develop a predictive model. We developed a machine learning-powered interactive dashboard. Integrating participatory planning approaches with the development of an interactive interface could enhance ongoing community engagement. Planning practices can evolve with AI in the loop.

Urban dynamics and their implication on greenness trends: A 25-year retrospective study of the changing face of tokyo metropolitan area

Global metropolises and their needs for green space are rising due to demographic urbanization. Some phenomena contradicted to prevailing understanding have been observed in metropolises, such as the “sprawl shrinkage” associated with the increasing built-up area despite declining populations, and the positive relationship between population and greenness. To study these storylines, we conceptualized and mapped 5 urban dynamics by cross-referencing the“increase, stable, and decrease”of built-up area and population density based on threshold values of an introduced Normalized Difference Index (NDI). Furthermore, Kruskal-Wallis H Test was used to analyze the influence of different urban dynamic patterns on 3 greenness trends (greening, browning, and stable greenspace). From 1995 to 2021, Tokyo Metropolitan Area (TMA) gradually transited from intense urban expansion to a stabilization of built-up area and population density in the city center, declining urbanization in the peri-urban areas, and “sprawl shrinkage” in the far-outskirts. Moreover, compared to other urban dynamics, the pattern of built-up areas increases with a population density reduction of over 5% were conducive to maintaining NDVI values of 0.75 or higher. In the future, the ongoing demographic urbanization is highly likely to further exacerbate the phenomenon of urban-suburban disparity and intra-suburban differentiation. We propose that Asian metropolises should enhance regional cooperation and public-private partnerships to address potential regional ecological imbalances. Additionally, it is necessary to maximize the greenness within the given urban dynamics through figuring out the spatial impact mechanisms of urban development on greenness change from a long-term perspective.

DESIGN STRATEGIES OF APARTMENT HOUSING WITH SHELTERS TAKING PANDEMIC RISKS INTO ACCOUNT: CURRENT TRENDS AND DEVELOPMENT DIRECTIONS

The article explores the issue of adaptation of living spaces to pandemic risks. It was determined that the creation of special isolation zones in new residential complexes is one of the key aspects. These premises must be equipped with everything necessary for a comfortable stay during quarantine, including separate bathrooms and autonomous ventilation systems, which will minimize contact between residents and prevent the spread of infections. It is well-founded that the design of ventilation systems is an important element in preventing the spread of viruses. Modern ventilation systems must ensure a constant flow of fresh air and effective removal of contaminated air. an important direction is the change in planning and zoning of living spaces. New approaches to planning take into account the possibility of reducing population density and creating conditions for social distance, so common areas should be spacious and ensure the possibility of maintaining a safe distance between people. Research has shown that increasing privacy, creating workspaces, eco-design and flexibility are also defining trends in the field of residential design. The pandemic leveled the concept of "Open-space" in favor of interior separatism, which allows creating isolated areas for work, recreation and other activities, which provides comfortable conditions for residents who are forced to spend more time at home. Innovative technologies, such as health monitoring systems and smart home systems, can significantly improve the safety and comfort of living. The introduction of such technologies makes it possible to quickly identify potential threats and take the necessary measures to neutralize them. The importance of implementing eco-design, which contributes to improving the mental and physical health of residents, has been revealed. Green areas on balconies and terraces stabilize the emotional state of people, creating private gardens in the structure of living space. Organizing space for self-isolation and reducing pandemic risks requires new approaches to planning living spaces, common spaces, and infrastructure. These changes contribute to the creation of a safer, more comfortable and adaptive living environment during the pandemic.

Does natural resource dependence restrict green development? An investigation from the “Belt and road” countries

Addressing natural resource dependence is integral to achieving the Sustainable Development Goals by promoting economic diversification, environmental sustainability, and climate resilience. This study explores the effect of natural resource dependence on green development by adopting the balanced panel dataset from the “Belt and Road” countries from 2005 to 2019. Notably, the novelty of our analysis lies in the empirical analysis using instrument-based techniques that consolidate the “green development curse hypothesis” in the Belt and Road countries. The mechanism analysis reveals that natural resource dependence curbs green development by weakening innovative capability, disturbing institutional quality, reducing population density, and crowding out human capital. Further, the dynamic panel threshold model handling endogeneity verifies the nonlinear relationship between natural resource dependence and green development. Interestingly, digital trade offers greater “resilience” than traditional trade, correcting the resource curse dilemma. Finally, heterogeneity analyses indicate that the green development curse hypothesis only exists in countries with high-level environmental regulations and resource-based countries.

Effects of Anaerobic Soil Disinfestation for Soilborne Disease and Weed Management on Baby Leaf Lettuce Performance in a High Tunnel Organic Production System

The use of high tunnels, which allows growers to extend their season and improve yields, is increasing in the Southeastern U.S., yet growers face challenges related to weed and disease management, particularly in organic systems. On-station experiments were conducted during fall 2021 and spring 2022 in a split-plot design to assess the efficacy of anaerobic soil disinfestation (ASD) in high tunnels for the organic production of direct-seeded baby leaf lettuce. Soil treatments (ASD, Compost, and Control) and lettuce types (romaine and oakleaf cultivars) were included in whole plots and subplots, respectively. The ASD-treated soils received molasses and granular organic fertilizer as carbon and nitrogen sources. The Compost treatment involved the application of yard waste-based compost and the same organic fertilizer, while the Control soils received organic fertilizer only. The ASD treatment period lasted 8 days rather than the typical 21-day period evaluated in Florida. Crop yield, biometrics (leafy dry matter content, specific leaf area, specific leaf weight), and lettuce quality attributes (leaf color, soluble solids content, total titratable acidity, ferric reducing antioxidant power, ascorbic acid content, total phenolics) were assessed following harvest. In both trials, numerical differences in lettuce fresh weight yield between soil treatments were evident, though not statistically significant. Differences in leaf quality attributes were driven by lettuce cultivar rather than soil treatments. Bottom rot incidence caused by Rhizoctonia solani was reduced by 93% and 87% in the ASD-treated plots compared with the Compost- and Control-treated soils during the spring 2022 trial. The ASD-treated soils had a reduced population density of broadleaf weeds in both baby leaf lettuce production trials. The current study presents novel evidence of the potential of integrating ASD into HT organic production systems without reducing the yield and quality attributes of direct-seeded baby leafy greens compared with common grower practices.

Surviving the Anthropocene: A Darwinian Guide

The fundamental theory of the survival of life on this planet is Darwinism. Darwinian evolution is about coping with change by changing, using what you have on hand to survive. The fuel for this process is evolutionary potential, which resides in preexisting variation. This preexisting variation allows living systems to move forward into an uncertain future. The biosphere is a complex evolutionary system that generates, stores, and uses its own potential to survive. This makes ecosystems robust, not fragile. That suggests we can use the biosphere without destroying it, but we need some guidelines. Those guidelines are embodied in the Four Laws of Biotics, which tell us how we can interact with the biosphere without endangering ourselves further. We can further improve humanity’s chances of survival as a technological species by (1) implementing the economics of well-being, (2) reducing population density by finding space in rural areas and revitalizing them into circularized economies, (3) regrowing sustainably by creating networks of cooperating circular economies, adding new modules when growth occurs, not consolidating into new densely populated and vulnerable urban centers, and (4) modifying social institutions to be responsive to the desires of the grassroots, even when those desires do not produce the expected outcomes. Darwinian principles provide humanity with a middle ground, a third way, between unattainable utopia and unacceptable apocalypse. We can alter our behavior now according to Darwinian principles, at great expense and difficulty, and extend or even improve upon the current state of the Anthropocene, or we can fail to act on our own behalf, experience a general collapse of technological society, and rebuild using those Darwinian principles to provide a more survivable future.

Paradoxical Exception to Island Tameness: Increased Defensiveness in an Insular Population of Rattlesnakes.

Island tameness results largely from a lack of natural predators. Because some insular rattlesnake populations lack functional rattles, presumably the consequence of relaxed selection from reduced predation, we hypothesized that the Santa Catalina Island, California, USA, population of the southern Pacific rattlesnake (Crotalus helleri, which possesses a functional rattle), would exhibit a decrement in defensive behavior relative to their mainland counterparts. Contrary to our prediction, rattlesnakes from the island not only lacked tameness compared to mainland snakes, but instead exhibited measurably greater levels of defensiveness. Island snakes attempted to bite 4.7 times more frequently as we endeavored to secure them by hand, and required 2.1-fold more time to be pinned and captured. When induced to bite a beaker after being grasped, the island snakes also delivered 2.1-fold greater quantities of venom when controlling for body size. The additional venom resulted from 2.1-fold larger pulses of venom ejected from the fangs. We found no effects of duration in captivity (2-36 months), which suggests an absence of long-term habituation of antipredator behaviors. Breeding bird surveys and Christmas bird counts indicated reduced population densities of avian predators on Catalina compared to the mainland. However, historical estimates confirmed that populations of foxes and introduced mammalian predators (cats and pigs) and antagonists (herbivorous ungulates) substantially exceeded those on the mainland in recent centuries, and therefore best explain the paradoxically exaggerated defensive behaviors exhibited by Catalina's rattlesnakes. These findings augment our understanding of anthropogenic effects on the behaviors of island animals and underscore how these effects can negatively affect human safety.

Confirmation of a four-way herbicide-resistant Palmer amaranth (Amaranthus palmeri) population in Iowa

Abstract Palmer amaranth (Amaranthus palmeri S. Watson) was first reported in Iowa in 2013 and has continued to spread across the state over the last decade. Importantly, A. palmeri is widely recognized as one of the more economically important weeds in production agriculture. The presence of A. palmeri in Iowa is concerning as the species has evolved resistance to nine herbicide sites of action, however, no formal characterization has been conducted on Iowa populations. Therefore, herbicide assays were conducted on an A. palmeri population collected in Harrison County, Iowa in 2023 (Southwest Palmer Amaranth, SWPA) and a known herbicide-susceptible population collected from Nebraska in 2001 (Palmer Amaranth Susceptible, PAS). The two populations were treated with preemergence and postemergence herbicides commonly used in Iowa. The treatments included preemergence applications of atrazine, metribuzin, and mesotrione and postemergence applications of atrazine, imazethapyr, glyphosate, lactofen, mesotrione, glufosinate, 2,4-D and dicamba at 1x and 4x the labeled rates. Survival frequency of SWPA was >90% when treated postemergence with 1x rates of imazethapyr, atrazine, glyphosate, and mesotrione compared to ≤6% for PAS. Both SWPA and PAS had 0% survival when treated with lactofen, glufosinate, 2,4-D, and dicamba at the 1x or 4x rates. Plant population density reduction for SWPA was 53% and 40% in response to 1x rates of preemergence-applied mesotrione and atrazine, respectively. Metribuzin applied preemergence reduced SWPA plant population density by >90% at both rates. Dose-response experiments revealed the 50% effective doses (ED50) of mesotrione, glyphosate, imazethapyr, and atrazine for SWPA were 9.5-,8.5-, 71- and 40-fold greater than for PAS, respectively. The results confirm that SWPA is four-way multiple herbicide-resistant. Amaranthus palmeri infestations are likely to continue to spread within Iowa, therefore diversified weed management programs that include early detection, rapid response, and effective multi-tactic management strategies will be required for control.

Prediction of the Birth Rate of Babies at Regional Hospitals in Salatiga City Using the Naïve Bayes Algorithm

Birth rates have a significant impact on population growth and large populations can be a burden on development. At the Regional General Hospital of Salatiga City, the numbers tend to change every year, with the population density that occurs in Salatiga City now making it a special concern. Therefore, the application of Data Mining Techniques with the Naive Bayes algorithm is expected to help predict the number of births in the future. The use of Data Mining with the Naive Bayes algorithm at the Salatiga City Regional General Hospital aims to calculate and predict the number of baby births. By analyzing the patterns of each variable and testing training data on testing data from 2019-2023 in Salatiga City, it is hoped that the Naive Bayes algorithm can be a solution to reduce population density figures in the coming year.

Toxicity and Histological Effects of Clove Buds’ Powder, Syzygium aromaticum Compared with Neomyl (Methomyl) for the Control of Monacha cartusiana and Theba pisana Snails

Bayoumi, Sh.M., N.A. Omar, A.H. Mohanna, Sh.A. Ismail, M. Abed, A.M. El-Sayed, M.A. Issa, F.I. El-Akhrasy and E.M. Abd El-Aal. 2024. Toxicity and Histological Effects of Clove Buds’ Powder, Syzygium aromaticum Compared with Neomyl (Methomyl) for the Control of Monacha cartusiana and Theba pisana Snails. Arab Journal of Plant Protection, 42(3): 318-327. https://doi.org/10.22268/AJPP-001246 A series of laboratory and field experiments were designed to evaluate control measures that can be utilized effectively to reduce population density and consequently the damage caused by certain land snail species Monacha cartusiana Müller and Theba pisana Müller. In addition, factors contributing towards safer control measures were investigated. When neomyl 8% and clove powder buds 40% were applied to control M. cartusiana and T. pisana under laboratory and field conditions, the toxicity effect of these applications on the tested land snail's digestive glands was investigated. The results obtained revealed that the mortality rate increased with the increase in the concentrations and exposure period. Under laboratory conditions, the mortality rate of T. pisana snail reached 100% when 2, 4, and 8% neomyl concentrations were utilized, whereas the mortality rate of the same snail reached 36.3% when clove powder 40% was utilized, 28 days after treatment. Under field conditions, the initial effect of the examined compounds reached 62.89% and 18.83% mortality rate when neomyl and clove treatments were applied, respectively. Furthermore, the residual effect with neomyl treatment gave a high mortality rate of 83.43%, compared to 28.88% for the clove powder treatment. Generally, it could be concluded that neomyl had the most toxic effect against M. cartusiana under field conditions. 8% neomyl treatment resulted in histological degeneration with alterations in the digestive cells’ cytoplasm. Numerous excretory vacuoles were found in the excretory cells. Calcium cells became granulated, cytoplasm vacuoles were abundant, and bizarre nuclei ranged from pyknosis to severe karyorrhexis and complete karyolysis. The results obtained also indicated that the toxicity effects of the 40% concentration of clove buds’ powder, 48 hours after treatment, were approximately the same on both treated land snail species. Keywords: Toxicity, histology, clove, neomyl, M. cartusiana, T. pisana

Low‐ and high‐intensity fire in the riparian savanna: Demographic impacts in an avian model species and implications for ecological fire management

Abstract Climate change is driving changes in fire frequency and intensity, making it more urgent for conservation managers to understand how species and ecosystems respond. In tropical monsoonal savannas—Earth's most fire‐prone landscapes—ecological fire management aims to prevent intense wildfires late in the dry season through prescribed low‐intensity burns early in the dry season. Riparian habitats embedded within tropical savannas represent critical refuges for biodiversity, yet are particularly fire‐sensitive. Better understanding of the impact of fire—including prescribed burns—on riparian habitats is therefore key but requires long‐term detailed post‐fire monitoring of species' demographic rates, as effects may persist and/or be delayed. We analyse impacts of (prescribed) low‐intensity and (prescribed but escaped) high‐intensity fire in northern Australian riparian and adjacent savanna habitat. We quantify multi‐year impacts on density, survival, reproduction and dispersal of an endangered riparian bird, the western purple‐crowned fairy‐wren (Malurus coronatus coronatus), in a well‐studied individually marked population. Following low‐intensity fire, bird density was reduced by >20% in burnt compared to adjacent unburnt riparian habitat for ≥2.5 years. This was a result of reduced breeding success and recruitment for 2 years immediately following fire, rather than mortality or dispersal of adults. In contrast, high‐intensity fire (in a dry year) resulted in a sharp decline in population density by 50% 2–8 months after fire, with no signs of recovery after 2.5 years. The decline in density was due to post‐fire adult mortality, rather than dispersal. Breeding success of the (few) remaining individuals was low but not detectably lower than in unburnt areas, likely because breeding success was poor overall due to prevailing dry conditions. Synthesis and applications. Even if there is no or very low mortality during fire, and no movement of birds away from burnt areas, both low‐ and high‐intensity fire in the riparian zone reduce population density. However, the mechanism by which this occurs, and recovery time, differs with fire intensity. To minimise impacts of fire on riparian zones in tropical savannas, we suggest employing low‐intensity prescribed burns under optimal conditions shortly after the breeding season.

Unsuitability of the gall‐inducing fly Eutreta xanthochaeta for biological control of Lantana camara in presence of other native hosts in nature

AbstractThe biological control of weeds requires the successful introduction and establishment of natural enemies into other regions, to reduce population densities of target species. Potential biocontrol agents are sought in the native region of target weed and should be highly specialized. The gall‐inducing fly Eutreta xanthochaeta Aldrich (Diptera: Tephritidae) is native to Mexico and has been brought into other regions of the world – such as Hawaii (USA), South Africa, and Australia – for the biological control of Lantana camara L. (Verbanaceae), although this not always proved to be successful. Here we investigate the trophic interactions of this fly species with two host plants inhabiting in sympatry, L. camara and Lippia myriocephala Schltdl. & Cham. (Verbenaceae), evaluating its preference through infestation rates, the gall distribution in the plant architecture, as well as the indirect impact upon production of inflorescences affecting the reproductive capacity of the plants. We found that the fly was not monophagous in its native range, and under natural conditions it preferred the wild host L. myriocephala in the presence of L. camara. Moreover, we found that gall formation was linked to changes in the host architecture along with the potential for reproduction, leading to increased terminal buds and a reduction in the inflorescences produced on the twigs where galls develop. Lantana camara consists of both horticultural hybrids and wild varieties resulting in unresolved taxonomic ambiguities. Hence, there may be adaptive limitations of this fly to distinct geographic races or climatic conditions in the various regions, which needs further investigation.

Effect of Bait and Light intensity of color traps of the population Ocnerogyla amanda Staudinger 1891 (LYMANTRIDAE: LEPIDOPTERA) Kane Kawai CHBUX

This study was carried out in the village of Kane kawai chbux, located in the Sulamani governorate of Iraq in 2021. Two options were used to suppress population destiny: a bait trap and a light trap. The effect of color and light density on the attractiveness of adults of the moth Ocnerogyia amanda species of moth leaf worm of fig was studied, and the results showed that light traps yellow color were more effective than white color, Whereas the means monthly captured of adults/trap had (6.278,14.400,12.078), and white light traps means captured adults/trap monthly had ( 6.830,10.488,10.080)The results of the statistical analysis also showed significant differences between white light traps and yellow light intensity with (50, 100, and 150) watts of bulb power, and traps with a 50-watt bulb had less influence on adult capture. Molasses with water at 1:9 and molasses with vinegar at 1:3. The mean monthly captured adults/trap had (7.304, 3.018, and 0.041).Fermented palm sugar and water were superior in attracting a significant number of captures as compared to vinegar and molasses. Molasses and vinegar were the least attractive. The conclusion is that bait traps are an attraction and capture, and that collectors and attraction are aids to light traps that capture most adults active at night as the best method to reduce population density, these are the two selected methods and their relationship as integrated pest management methods.

Influence of Settlement Activities on Sustainable Households’ Livelihoods of the Inhabitants in Mount Elgon Forest, Bungoma County, Kenya

Mount Elgon Forest has declined primarily due to anthropogenic activities. The aim of this paper was to investigate the influence of settlement activities on sustainable household’s livelihoods of inhabitants in Mount Elgon Forest, Bungoma County, Kenya. This study used cross-sectional research design and mixed methodology. The target population was 12842 household heads, 4 ward administrators, 12 chiefs, 1 Kenya Forest service personnel and 1 NEMA official. A sample of 373 household heads, 4 ward administrators, 12 chiefs, 1 Kenya Forest Service Personnel and 1 NEMA official took part in the study. Questionnaires, interview guides and Focus Group Discussions were used to collect data. Validity was determined by consulting supervisors while reliability was ascertained through piloting and use of Cronbach Alpha Coefficient. Quantitative data was analysed using frequencies, percentages, means, Standard deviation and Pearson Correlation analysis. Qualitative data was thematically classified and arranged before being reported in narrations and quotations. Analyzed data was presented using tables and figures. The study found a significant positive correlation between settlement activities and sustainable households’ livelihoods (r = .614; p = .000). It was recommended that there was a need to devise ways of reducing population density and land fragmentation leading to reduced dependency on forest products. The findings of the study will be crucial to professional bodies and institutions such as Kenya Forest service, Kenya wildlife service and NEMA in relooking at the approaches that enhance livelihoods among forest users and thus come up with strategies for effective management of forests improving on sustainable livelihoods.

Spatiotemporal transmission of infectious particles in environment: A case study of Covid-19

This study explores the dynamic transmission of infectious particles due to COVID-19 in the environment using a spatiotemporal epidemiological approach. We proposed a novel multi-agent model to simulate the spread of COVID-19 by considering several influencing factors. The model divides the population into susceptible and infected and analyzes the impact of different prevention and control measures, such as limiting the number of people and wearing masks on the spread of COVID-19. The findings suggest that reducing population density and wearing masks can significantly reduce the likelihood of virus transmission. Specifically, the research shows that if the population moves within a fixed range, almost everyone will eventually be infected within 1 h. When the population density is 50%, the infection rate is as high as 96%. If everyone does not wear a mask, nearly 72.33% of the people will be infected after 1 h. However, when people wear masks, the infection rate is consistently lower than when they do not wear masks. Even if only 25% of people wear masks, the infection rate with masks is 27.67% lower than without masks, which is strong evidence of the importance of wearing a mask. As people's daily activities are mostly carried out indoors, and many super-spreading events of the new crown epidemic also originated from indoor gatherings, the research on indoor epidemic prevention and control is essential. This study provides decision-making support for epidemic preventions and controls and the proposed methodology can be used in other regions and future epidemics.

Could non-native species boost their chances of invasion success by socializing with natives?

Most invasions start with the introduction of a few individuals and the majority fail to establish and become invasive populations. A possible explanation for this is that some species are subject to Allee effects-disadvantages of low densities-and fail to perform vital activities due to the low availability of conspecifics. We propose that 'facilitation' from native individuals to non-natives through heterospecific sociability could enhance chances of the latter establishing in novel environments by helping them avoid Allee effects and even reducing the minimum number of non-native individuals necessary to achieve the density for a viable population (the Allee effect threshold). There is evidence from experiments carried out with freshwater fish, snails, lizards, mussels and bird that supports the idea of heterospecific sociability between native and non-native species as a process to promote invasion success. We propose that to understand invasion success in social non-native species we need to investigate how they integrate into the recipient community. Furthermore, to manage them, it may be necessary to reduce population density not just below the Allee effect threshold but also to understand how natives could help them shift the conspecific Allee effect threshold to their benefit. This article is part of the theme issue 'Mixed-species groups and aggregations: shaping ecological and behavioural patterns and processes'.

Successional effects of cover cropping and deep tillage on suppression of plant-parasitic nematodes and soilborne fungal pathogens.

Cover crops can suppress soilborne nematodes and fungal pathogens by serving as a poor host to pathogens and producing allelopathic compounds. Yet, cultural practices can influence their effectiveness. Cover crop and weedy fallow rotations and their interactions with deep tillage were evaluated from 2019 to 2021 in a three-season vegetable cropping system (spring tomato, fall squash, and winter cabbage) for their suppressive effects on soilborne diseases. Experimental plots were arranged in a split-plot 2 × 4 factorial design in randomized complete blocks. Whole-plot tillage treatments were shallow-tilled or deep-tilled. Subplots had two factors of crop rotations: rotation type (cover crop [spring or fall sunn hemp or winter rye] or weedy fallow) and rotation season. Independent of tillage practice, sunn hemp and weedy fallow reduced population density and root galling severity of root-knot nematode (Meloidogyne incognita) for the first subsequent vegetable compared to the all-vegetable rotation (P < 0.05) but had little effect on fungal pathogens. Fall sunn hemp had higher plant biomass and reduced gall severity for the second subsequent vegetable. Spring and fall sunn hemp improved vegetable yields. Winter rye only reduced ring nematodes (Mesocriconema spp.) population density in the first subsequent vegetable. Deep tillage reduced incidence of fungal pathogens of Rhizoctonia solani and Sclerotinia sclerotiorum, and population density of stubby-root nematode (Nanidorus minor). Sunn hemp is effective in suppressing M. incognita, whereas deep tillage can be used to suppress R. solani, S. sclerotiorum, and N. minor in vegetable production systems. © 2023 Society of Chemical Industry.