Impact ofProsopis julifloraon Kenya's semi-arid and arid ecosystems and local livelihoods

Indigenous communities' perceptions reveal threats and management options of wild edible plants in semiarid lands of northwestern Kenya

BACKGROUND

Understanding how local communities perceive threats and management options of wild edible plants (WEPs) is essential in developing their conservation strategies and action plans. Due to their multiple use values, including nutrition, medicinal, construction, and cultural as well as biotic and abiotic pressures, WEPs are exposed to overexploitation, especially within arid and semiarid lands, and hence the need to manage and conserve them. We demonstrate how an understanding of indigenous communities' perceptions could be achieved through an integrated participatory approach involving focus group discussions (FGDs) and field plot surveys.

METHODS

We conducted three FGDs between October 2020 and April 2021 within three community units in northwestern Kenya with different socioeconomic and environmental characteristics. We subsequently surveyed 240 field plots of size 1 ha each to assess threats facing WEPs within a 5 km buffer radius in every study community. We compared ranks of threats and management options across community units.

RESULTS

Rankings of threats and management options differed across the three study communities. We obtained strong positive linear relationships between field and FGD rankings of threats facing WEPs. Climate change, overstocking, overharvesting, and invasive species were the highest-ranked threats. Mitigation of climate change, local knowledge preservation, selection, propagation, processing, and marketing of WEPs ranked high among possible management options irrespective of the socioeconomic and environmental characteristics of the community unit.

CONCLUSIONS

Our approach emphasizes the relevance of leveraging indigenous communities' perceptions and conducting field plot surveys to assess threats and management options for WEPs. Evaluating the effectiveness and cost-benefit implications of implementing the highly ranked management options could help determine potentially suitable habitats of the WEPs for conservation and management purposes, especially for priority WEPs.

Effects of prosopis juliflora on plant diversity on rangeland in Shilabo District, Somali Regional State, Ethiopia

Shilabo District of Somali Regional State in Ethiopia is economically important for livestock production. The indigenous pasturelands are increasingly being invaded by Prosopis juliflora, thereby threatening their livestock production capacity. However, the ecological impact of Prosopis' invasion has yet to be investigated. This study was conducted to examine the effects of Prosopis juliflora on plant species abundance, diversity, and occurrence. Vegetation samples were collected from three 20-m by 20-m sub-plots nested within 100-m by 100-m main plots that were purposefully selected in target study sites and replicated three times in both invaded and uninvaded areas. The study recorded 44 plant species, of which thirteen species occurred in both invaded and uninvaded areas, 13 species in invaded areas and 24 in uninvaded areas. The collected data were analyzed using the Statistical Package for Social Sciences (SPSS) version 26, and an independent t-test was used to determine the statistical significance difference between invaded and uninvaded areas in terms of number, density, important value index, diversity, abundance, evenness, and richness of plant species. These plant parameters were recorded in invaded and uninvaded areas with species numbers of 678.33 and 1763, densities of 226.00 and 366.98/ha, abundances of 254.04 and 409.45, important value indexes of 15.00 and 9.68, Shannon diversity of 1.56 and 3.40, evenness of 0.52, and 0.99, and richness of 1.30 and 1.35, respectively. The uninvaded area had a significantly higher species diversity index (3.40) than the invaded area (1.56; P 0.00). Similarly, the number of plant species, density, abundance, important value index, species evenness, and richness were significantly higher in uninvaded areas than invaded areas (p < 0.000).

Habitat Diversity, Stability, and Productivity of Malaria Vectors in Irrigated and Nonirrigated Ecosystems in Western Kenya

Several sub-Saharan African countries rely on irrigation for food production. This study examined the impact of environmental modifications resulting from irrigation on the ecology of aquatic stages of malaria vectors in a semi-arid region of western Kenya. Mosquito larvae were collected from irrigated and non-irrigated ecosystems during seasonal cross-sectional and monthly longitudinal studies to assess habitat availability, stability, and productivity of anophelines in temporary, semipermanent, and permanent habitats during the dry and wet seasons. The duration of habitat stability was also compared between selected habitats. Emergence traps were used to determine the daily production of female adult mosquitoes from different habitat types. Malaria vectors were morphologically identified and sibling species subjected to molecular analysis. Data was statistically compared between the two ecosystems. After aggregating the data, the overall malaria vector productivity for habitats in the two ecosystems was estimated. Immatures of the malaria vector (Anopheles arabiensis) Patton (Diptera: Culicidae) comprised 98.3% of the Anopheles in both the irrigated and non-irrigated habitats. The irrigated ecosystem had the most habitats, higher larval densities, and produced 85.8% of emerged adult females. These results showed that irrigation provided conditions that increased habitat availability, stability, and diversity, consequently increasing the An. arabiensis production and potential risk of malaria transmission throughout the year. The irrigated ecosystems increased the number of habitats suitable for Anopheles breeding by about 3-fold compared to non-irrigated ecosystems. These results suggest that water management in the irrigation systems of western Kenya would serve as an effective method for malaria vector control.

Prospective Role of Indigenous Leafy Vegetables as Functional Food Ingredients

Indigenous leafy vegetables (ILVs) play a pivotal role in sustaining the lives of many people of low socio-economic status who reside in rural areas of most developing countries. Such ILVs contribute to food security since they withstand harsher weather and soil conditions than their commercial counterparts and supply important nutrients such as dietary fibre, vitamins and minerals. Furthermore, ILVs contain bioactive components such as phenolic compounds, flavonoids, dietary fibre, carotene content and vitamin C that confer health benefits on consumers. Several studies have demonstrated that regular and adequate consumption of vegetables reduces risks of chronic conditions such as diabetes, cancer, metabolic disorders such as obesity in children and adults, as well as cardiovascular disease. However, consumption of ILVs is very low globally as they are associated with unbalanced and poor diets, with being food for the poor and with possibly containing toxic heavy metals. Therefore, this paper reviews the role of ILVs as food security crops, the biodiversity of ILVs, the effects of processing on the bioactivity of ILVs, consumer acceptability of food derived from ILVs, potential toxicity of some ILVs and the potential role ILVs play in the future of eating.

Prioritization of invasive alien species with the potential to threaten agriculture and biodiversity in Kenya through horizon scanning

Invasive alien species (IAS) rank among the most significant drivers of species extinction and ecosystem degradation resulting in significant impacts on socio-economic development. The recent exponential spread of IAS in most of Africa is attributed to poor border biosecurity due to porous borders that have failed to prevent initial introductions. In addition, countries lack adequate information about potential invasions and have limited capacity to reduce the risk of invasions. Horizon scanning is an approach that prioritises the risks of potential IAS through rapid assessments. A group of 28 subject matter experts used an adapted methodology to assess 1700 potential IAS on a 5-point scale for the likelihood of entry and establishment, potential socio-economic impact, and impact on biodiversity. The individual scores were combined to rank the species according to their overall potential risk for the country. Confidence in individual and overall scores was recorded on a 3-point scale. This resulted in a priority list of 120 potential IAS (70 arthropods, 9 nematodes, 15 bacteria, 19 fungi/chromist, 1 viroid, and 6 viruses). Options for risk mitigation such as full pest risk analysis and detection surveys were suggested for prioritised species while species for which no immediate action was suggested, were added to the plant health risk register and a recommendation was made to regularly monitor the change in risk. By prioritising risks, horizon scanning guides resource allocation to interventions that are most likely to reduce risk and is very useful to National Plant Protection Organisations and other relevant stakeholders.

Community perceptions towards invasion of Prosopis juliflora, utilization, and its control options in Afar region, Northeast Ethiopia

This study aimed to assess community perceptions towards invasion of Prosopis juliflora, utilization, and its control options in Afar region, Northern Ethiopia. Using purposive sampling and stratified random methods, 20 members of key informants and 154 households from four sites of Awash Fentale and Amibara Districts were selected. For data analysis, we used Kruskal Wallis non-parametric tests of K independent samples. About 30% of respondents in Amibara and 29% in Awash Fentale reported that Prosopis juliflora was largely introduced into their landscape by livestock. It showed that 29% of the respondents in Awash Fentale and 41% in Amibara responded that Prosopis juliflora largely invaded and affected rangelands. Morevover, about 1% of respondents in Awash Fentale and 14% in Amibara argued that Prosopis juliflora hindered movements of livestock. In addition, 30% of respondents in Amibara and 29% in Awash Fentale believe that Prosopis juliflora was largely dispersed by livestock. It showed that 20% of households in Awash Fentale and 41% in Amibara have the notion that Prosopis juliflora majorly impacted rangelands. Whereas 1.3% of respondents in Awash Fentale and 14% in Amibara argued that Prosopis juliflora have hampered the movement of livestock. Thus, the afromentioned findings are implications for management of rangelands. With regard to the control of Prosopis juliflora invasions, 12% of respondents in Awash Fentale and 33% in Amibara District tried control its expansion by fire. About 10% of respondents in Awash Fentale and 9% in Amibara district managed Prosopis juliflora expansion by its utilization, whereas, in Awash Fentale (11%) and Amibara (8%) households indicated that invasion of Prosopis juliflora could be controlled by mechanical methods. It is advisable to do some managerial work to reverse these impacts as perceived by local communities in the study area to avert the aggressive proliferation of Prosopis juliflora in the region.

Effects of development interventions on pastoral livelihoods in Turkana County, Kenya

Turkana County has a long history of drought and development interventions and remains one of the poorest counties in Kenya. In Turkana, livelihoods are increasingly under threat because of climate change, conflict, and the changing land use and management. There are complex interactions between the multiple drivers of change in landscapes and livelihoods in the region. The question addressed here is: How have external development interventions contributed to the changing pastoralist livelihoods in Turkana? This study is specific to the lower part of the Turkwel River basin, particularly the Nanyee irrigated area in Turkwel, Loima sub-County of Turkana County. This article examines the external development interventions during the colonial, post-independence, and contemporary periods to reveal the ways that land use practices and livelihoods have changed across these periods. Land use practices are changing due to the growing human population, droughts, urbanization, and dispossession of grazing areas through state and donor-supported interventions. It is suggested in this article that the change from a system of customary, unrestricted grazing to one of enclosed pastures has threatened pastoral territories, as well as cultures and livelihoods over the past six decades. The new set of development interventions introduced by international and national actors have failed to support local livelihoods, instead joining the list of existing problems that undermine pastoralism, including drought, livestock diseases, and cattle rustling.

Floristics and Diversity of Invasive Alien Plant Species in Humbo District, South Ethiopia

Deliberate and unintentional introduction of invasive alien plant species on native biodiversity by aid agencies and other bodies directly or indirectly are being a series of problems on the economy, ecology, politics, and health of life on earth. Identifying and compiling floristics and the status of invasive alien species and identifying which have viable populations are necessary to manage the ecosystems. The present study is therefore intended to provide information for concerned bodies on the area which needs management priority computing the composition, structure, and diversity of invasive alien plants. A field assessment was conducted to determine the distribution and heterogeneity of invasive alien plant species, and then, six kebeles were chosen and transact lines were laid using a purposeful sampling technique. The vegetation and environment data were collected from farmland, grazing land, fallow land, and road sides using 95 subquadrats (5 m × 5 m) set in the center and corner of 19 main quadrats (20 m × 20 m). The voucher specimens collected were taken to the Herbarium of Ethiopia (ETH) for taxonomic identification and future reference. The frequency and density of floristics data were analyzed using MS Excel version 2010, and species diversity was calculated using Shannon (H′), Simpson (D), and evenness (E) indices. Among 35 alien plant species invading natural vegetation in Ethiopia, 25 alien plant species were found in the Humbo district of the Wolaita zone. The densest invasive alien plant species in the area were Parthenium hysterophorus consisting of 15197 individuals/ha, followed by Richardia scabra consisting of 11908 individuals/ha, Xanthium strumarium consisting of 7292 individuals/ha, and Ocimum forskolei consisting of 6280 individuals/ha. The highest species diversity was computed in fallow land (H′ = 2.369), which is followed by farmland (H′ = 1.627) and grazing land (H′ = 1.419). The higher the density of the invasive alien species, the higher the ability to change the structure and diversity of native species of the area results in a decrease in the function and services of the ecosystem. Therefore, management methods must prioritize land types that had the highest diversity of invasive alien species.

Insecticide resistance status of Anopheles arabiensis in irrigated and non-irrigated areas in western Kenya

BACKGROUND

Malaria control in Kenya is based on case management and vector control using long-lasting insecticidal nets (LLINs) and indoor residual spraying (IRS). However, the development of insecticide resistance compromises the effectiveness of insecticide-based vector control programs. The use of pesticides for agricultural purposes has been implicated as one of the sources driving the selection of resistance. The current study was undertaken to assess the status and mechanism of insecticide resistance in malaria vectors in irrigated and non-irrigated areas with varying agrochemical use in western Kenya.

METHODS

The study was carried out in 2018-2019 in Homa Bay County, western Kenya. The bioassay was performed on adults reared from larvae collected from irrigated and non-irrigated fields in order to assess the susceptibility of malaria vectors to different classes of insecticides following the standard WHO guidelines. Characterization of knockdown resistance (kdr) and acetylcholinesterase-inhibiting enzyme/angiotensin-converting enzyme (Ace-1) mutations within Anopheles gambiae s.l. species was performed using the polymerase chain reaction (PCR) method. To determine the agricultural and public health insecticide usage pattern, a questionnaire was administered to farmers, households, and veterinary officers in the study area.

RESULTS

Anopheles arabiensis was the predominant species in the irrigated (100%, n = 154) area and the dominant species in the non-irrigated areas (97.5%, n = 162), the rest being An. gambiae sensu stricto. In 2018, Anopheles arabiensis in the irrigated region were susceptible to all insecticides tested, while in the non-irrigated region reduced mortality was observed (84%) against deltamethrin. In 2019, phenotypic mortality was decreased (97.8-84% to 83.3-78.2%). In contrast, high mortality from malathion (100%), DDT (98.98%), and piperonyl butoxide (PBO)-deltamethrin (100%) was observed. Molecular analysis of the vectors from the irrigated and non-irrigated areas revealed low levels of leucine-serine/phenylalanine substitution at position 1014 (L1014S/L1014F), with mutation frequencies of 1-16%, and low-frequency mutation in the Ace-1R gene (0.7%). In addition to very high coverage of LLINs impregnated with pyrethroids and IRS with organophosphate insecticides, pyrethroids were the predominant chemical class of pesticides used for crop and animal protection.

CONCLUSION

Anopheles arabiensis from irrigated areas showed increased phenotypic resistance, and the intensive use of pesticides for crop protection in this region may have contributed to the selection of resistance genes observed. The susceptibility of these malaria vectors to organophosphates and PBO synergists in pyrethroids offers a promising future for IRS and insecticide-treated net-based vector control interventions. These findings emphasize the need for integrated vector control strategies, with particular attention to agricultural practices to mitigate mosquito resistance to insecticides.

Global guidelines for the sustainable use of non-native trees to prevent tree invasions and mitigate their negative impacts

Sustainably managed non-native trees deliver economic and societal benefits with limited risk of spread to adjoining areas. However, some plantations have launched invasions that cause substantial damage to biodiversity and ecosystem services, while others pose substantial threats of causing such impacts. The challenge is to maximise the benefits of non-native trees, while minimising negative impacts and preserving future benefits and options.

A workshop was held in 2019 to develop global guidelines for the sustainable use of non-native trees, using the Council of Europe – Bern Convention Code of Conduct on Invasive Alien Trees as a starting point.

The global guidelines consist of eight recommendations: 1) Use native trees, or non-invasive non-native trees, in preference to invasive non-native trees; 2) Be aware of and comply with international, national, and regional regulations concerning non-native trees; 3) Be aware of the risk of invasion and consider global change trends; 4) Design and adopt tailored practices for plantation site selection and silvicultural management; 5) Promote and implement early detection and rapid response programmes; 6) Design and adopt tailored practices for invasive non-native tree control, habitat restoration, and for dealing with highly modified ecosystems; 7) Engage with stakeholders on the risks posed by invasive non-native trees, the impacts caused, and the options for management; and 8) Develop and support global networks, collaborative research, and information sharing on native and non-native trees.

The global guidelines are a first step towards building global consensus on the precautions that should be taken when introducing and planting non-native trees. They are voluntary and are intended to complement statutory requirements under international and national legislation. The application of the global guidelines and the achievement of their goals will help to conserve forest biodiversity, ensure sustainable forestry, and contribute to the achievement of several Sustainable Development Goals of the United Nations linked with forest biodiversity.

Sustainability Analysis of Prosopis juliflora (Sw.) DC Based Restoration of Degraded Land in North India

Restoration of marginal and degraded lands is essential for regaining biodiversity and ecosystems services, and thereby attaining UN-Sustainable Development Goals. During the last few decades, many fast growing and hardy trees have been introduced worldwide to restore the marginal and degraded lands for ecosystem stability. Unfortunately, most of these introduced species have become invasive and invaded the nearby productive systems, leading to significant biodiversity loss and land degradation. Therefore, it is imperative to conduct a sustainability analysis of the introduced species for necessary course correction and also for preventing the future utilisation of such species for land restoration. With this backdrop, the present study was conducted to analyse the socio-ecological impacts of a widely used species, i.e., Prosopis juliflora (Sw.) DC based restoration of degraded land of Lucknow, North India. For this, ecological (soil quality and plant biodiversity) and social (livelihood) indicators have been studied over a period of two years (2015–16) through direct field sampling and questionnaire-based surveys. While there was a positive difference (p < 0.01) in the key physico-chemical properties of the P. juliflora-invaded soil than the non-invaded site, the belowground microbial load was significantly lower (19.46 × 106 g−1 of soil) in invaded land as compared to the non-invaded one (31.01 × 106 g−1). Additionally, the invasion of P. juliflora had significantly reduced the biodiversity by displacing the local flora such as Achyranthes aspera L., Amaranthus spinosus L., Cynodon dactylon (L.) Pers, Euphorbia hirta L., etc. The invaded area had only eight plant species having an effective number of species (ENS) of 7.2, whereas the non-invaded area had the presence of 26 plant species with an ENS of 23.8. Although the local people utilised P. juliflora as fuelwood mostly during summer and winter seasons, the invasion resulted in a fodder deficit of 419.97 kg household−1 y−1 leading to resource scarcity in the invaded area in comparison to the non-invaded area. Ecodistribution mapping clearly showed that P. juliflora is already found in most of the tropical and subtropical countries (~103) including in India and has become invasive in many countries. Therefore, we recommend that P. juliflora must be wisely used for the land restoration programs targeted during the United Nations Decade of Ecosystem Restoration (2021–2030) as this species has invasive traits and thereby reduces the ecosystem sustainability of the invaded areas.

Invasive Mesquite (Prosopis juliflora), an Allergy and Health Challenge

Mesquite (Prosopis juliflora (Sw.) DC), is an medium-sized tree (family Fabaceae, subfamily Mimosoideae), that has been intorcuded around the world. It is a noxious invasive species in Africa, Asia, and the Arabian Peninsula and a source of highly allergenic pollen in. The present article reviews the adverse allergenic effects of P. juliflora pollen on human and animal health. Several studies have diagnosed that allergenic pollens from Prosopis spp. can provoke respiratory problems. Prosopis pollen extracts have 16 allergenic components of which nine proteins were recognized as major allergens with some of them showing cross-reactivity. Clinically, understanding Prosopis pollen production, flowering seasonality, pollen load, and dispersal in the atmosphere are important to avoid allergic consequences for local inhabitants. Climate change and other pollution can also help to further facilitate allergenic issues. Furthermore, we document other human and animal health problems caused by invasive Prosopis trees. This includes flesh injuries, dental and gastric problems, and the facilitation of malaria. This review summarizes and enhances the existing knowledge about Prosopis flowering phenology, aeroallergen, and other human and animal health risks associated with this noxious plant.

Livelihood benefits and costs from an invasive alien tree (Acacia dealbata) to rural communities in the Eastern Cape, South Africa

The negative effects of invasive alien species (IAS) are increasingly invoked to justify widespread and usually top-down approaches for their management or eradication. However, very little of the research or discourse is based on investigating local perceptions, uses and struggles with IAS, and how their presence influences and changes local livelihoods. The objective of this study was to assess the perceptions and livelihood uses of Acacia dealbata by local communities at three localities in the montane grasslands of the Eastern Cape, South Africa, using a combination of random household interviews, focus group discussions and participatory tools. We calculated direct-use values for each product and household (based on quantity used and local prices) and disaggregated these by gender of the household head and wealth quartiles. The results revealed the dualistic role of A. dealbata in local livelihoods. On the one hand, A. dealbata was widely used for firewood (100% of households), tools (77%) and construction timber (73%), with limited use for traditional medicines and forage. The cumulative value of approximately ZAR 2870 (±US$224) per household per year (across all households) represents considerable cash saving to households, most of whom are quite poor by national and international measures. On the other hand, the increasing extent of A. dealbata (93% said it was increasing) exacerbates local household vulnerability though reported reductions in cultivated areas, crop yields and forage production, and allegedly higher risks of crime. This quandary is well encapsulated by the considerable majority of respondents (84%) not wanting higher extents and densities of A. dealbata, but an equally high majority not wanting its total removal from local landscapes. Most respondents disliked A. dealbata in fields, close to homesteads or along primary access routes, and were more tolerant of it away from such sites. Institutional and use dynamics have varied over several decades in response to the changing extent and densities of A. dealbata and the broader political and socio-economic contexts. These results indicate that greater efforts are required to understand perceptions and uses of IAS by the people who live with them, and to direct such understanding into more spatially and temporally contextualised response strategies where required.

The role of invasive alien species in shaping local livelihoods and human well-being: A review

Invasive alien species are a well-recognised driver of social-ecological change globally. Much research has focused on ecological impacts, but the role of invasive species for livelihoods and human well-being is less well known. Understanding the effects (benefits and costs) of invasive species on livelihoods and human well-being is important for guiding policy formulation and management. Here we review the literature on the role of invasive species in livelihoods to assess what is known, identify knowledge gaps and provide recommendations for future research. Literature was collected using key word searches and included both journal publications and grey literature. Slightly less than half (48%) of species studied had both substantial positive and negative impacts on local livelihoods (e.g. Australian Acacia spp. species; Camelus dromedaries; Lantana camara; Prosopis spp.), with 37% inducing mainly costs (Chromolaena odorata; Lissachatina fulica; Opuntia stricta) and 16% producing mainly benefits (Opuntia ficus-indica; Acacia spp.). Some species, such as Acacia dealbata, fell into different categories depending on the social-ecological context. Key benefits or services included the provision of fuelwood, fodder, timber and food products for local households communities and to a lesser extent supporting and regulating services such as soil improvement and shade. A number of species also provided cultural services such as recreation and spiritual values and provided many with an opportunity to earn a cash income. However, invasive species also harm livelihoods and increase vulnerability through encroaching on land and reducing mobility or access. They can also decrease the supply of natural resources used by households and reduce agricultural production (livestock and/or crops) which can result in losses of income and increased vulnerability. Furthermore, some invasive species were seen to have negative implications for human health and safety and reduce the cultural value of landscapes. Economic impacts on livelihoods as a result of invasive species were highly variable and very dependent on the social-ecological contexts. These negative implications can reduce resilience and adaptive capacity of households and communities thus increasing their vulnerability to change. Drawing on case studies we highlight that efforts for managing invasive species need to safeguard livelihood benefits while mitigating negative impacts. In concluding we highlight future research and policy needs on the topic of invasive species, livelihoods and human well-being.

Would the control of invasive alien plants reduce malaria transmission? A review

Vector control has been the most effective preventive measure against malaria and other vector-borne diseases. However, due to concerns such as insecticide resistance and budget shortfalls, an integrated control approach will be required to ensure sustainable, long-term effectiveness. An integrated management strategy should entail some aspects of environmental management, relying on coordination between various scientific disciplines. Here, we review one such environmental control tactic: invasive alien plant management. This covers salient plant-mosquito interactions for both terrestrial and aquatic invasive plants and how these affect a vector's ability to transmit malaria. Invasive plants tend to have longer flowering durations, more vigorous growth, and their spread can result in an increase in biomass, particularly in areas where previously little vegetation existed. Some invasive alien plants provide shelter or resting sites for adult mosquitoes and are also attractive nectar-producing hosts, enhancing their vectorial capacity. We conclude that these plants may increase malaria transmission rates in certain environments, though many questions still need to be answered, to determine how often this conclusion holds. However, in the case of aquatic invasive plants, available evidence suggests that the management of these plants would contribute to malaria control. We also examine and review the opportunities for large-scale invasive alien plant management, including options for biological control. Finally, we highlight the research priorities that must be addressed in order to ensure that integrated vector and invasive alien plant management operate in a synergistic fashion.

The potential impact of invasive woody oil plants on protected areas in China under future climate conditions

Biodiesel produced from woody oil plants is considered a green substitute for fossil fuels. However, a potential negative impact of growing woody oil plants on a large scale is the introduction of highly invasive species into susceptible regions. In this study, we examined the potential invasion risk of woody oil plants in China's protected areas under future climate conditions. We simulated the current and future potential distributions of three invasive woody oil plants, Jatropha curcas, Ricinus communis, and Aleurites moluccana, under two climate change scenarios (RCP2.6 and RCP8.5) up to 2050 using species distribution models. Protected areas in China that will become susceptible to these species were then identified using a spatial overlay analysis. Our results showed that by 2050, 26 and 41 protected areas would be threatened by these invasive woody oil plants under scenarios RCP2.6 and RCP8.5, respectively. A total of 10 unique forest ecosystems and 17 rare plant species could be potentially affected. We recommend that the invasive potential of woody oil plants be fully accounted for when developing forest-based biodiesel, especially around protected areas.

The invasive shrub Prosopis juliflora enhances the malaria parasite transmission capacity of Anopheles mosquitoes: a habitat manipulation experiment

Background

A neglected aspect of alien invasive plant species is their influence on mosquito vector ecology and malaria transmission. Invasive plants that are highly attractive to Anopheles mosquitoes provide them with sugar that is critical to their survival. The effect on Anopheles mosquito populations was examined through a habitat manipulation experiment that removed the flowering branches of highly attractive Prosopis juliflora from selected villages in Mali, West Africa.

Methods

Nine villages in the Bandiagara district of Mali were selected, six with flowering Prosopis juliflora, and three without. CDC-UV light traps were used to monitor their Anopheles spp. vector populations, and recorded their species composition, population size, age structure, and sugar feeding status. After 8 days, all of the flowering branches were removed from three villages and trap catches were analysed again.

Results

Villages where flowering branches of the invasive shrub Prosopis juliflora were removed experienced a threefold drop in the older more dangerous Anopheles females. Population density dropped by 69.4% and the species composition shifted from being a mix of three species of the Anopheles gambiae complex to one dominated by Anopheles coluzzii. The proportion of sugar fed females dropped from 73 to 15% and males from 77 to 10%.

Conclusions

This study demonstrates how an invasive plant shrub promotes the malaria parasite transmission capacity of African malaria vector mosquitoes. Proper management of invasive plants could potentially reduce mosquito populations and malaria transmission.

A preliminary assessment of the extent and potential impacts of alien plant invasions in the Serengeti-Mara ecosystem, East Africa

This article provides a preliminary list of alien plant species in the Serengeti-Mara ecosystem in East Africa. The list is based on broad-scale roadside surveys in the area and is supplemented by more detailed surveys of tourist facilities in the Masai-Mara National Reserve and adjoining conservancies. We encountered 245 alien plant species; significantly more than previous studies, of which 62 (25%) were considered to have established self-perpetuating populations in areas away from human habitation. These included species which had either been intentionally or accidentally introduced. Of the 245 alien plants, 212 (including four species considered to be native to the region) were intentionally introduced into gardens in the National Reserve and 51 (24%) had established naturalised populations within the boundaries of these tourism facilities. Of the 51 naturalised species, 23 (11% of the 212 alien species) were recorded as being invasive within the ecosystem, outside of lodges and away from other human habitation. Currently, the Serengeti-Mara ecosystem is relatively free of widespread and abundant invasive alien plants, with a few exceptions, but there are extensive populations outside of the ecosystem, particularly to the west, from where they could spread. We address the potential impacts of six species that we consider to pose the highest risks (Parthenium hysterophorus, Opuntia stricta, Tithonia diversifolia, Lantana camara, Chromolaena odorata and Prosopis juliflora). Although invasive alien plants pose substantial threats to the integrity of the ecosystem, this has not yet been widely recognised. We predict that in the absence of efforts to contain, or reverse the spread of invasive alien plants, the condition of rangelands will deteriorate, with severe negative impacts on migrating large mammals, especially wildebeest, zebra and gazelles. This will, in turn, have a substantial negative impact on tourism, which is a major economic activity in the area.Conservation implications: Invasive alien plants pose significant threats to the integrity of the Serengeti-Mara ecosystem and steps will need to be taken to prevent these impacts. The most important of these would be the removal of alien species from tourist facilities, especially those which are known to be naturalised or invasive, the introduction of control programmes aimed at eliminating outlier invasive plant populations to slow down the spread, and the widespread use of biological control wherever possible.

Stakeholder perceptions and practices regarding Prosopis (mesquite) invasions and management in South Africa

Invasive alien trees impact the environment and human livelihoods. The human dimensions of such invasions are less well understood than the ecological aspects, and this is hindering the development of effective management strategies. Semi-structured interviews were undertaken to investigate the knowledge and perceptions of Prosopis between different stakeholder groups. Chi-squared tests, Welch ANOVAs, and Principle Component Analyses were run. Factors such as land tenure and proximity to invasions were especially important for explaining differences in perceptions and practices relating to Prosopis among different stakeholder groups. Most respondents were aware of Prosopis and considered it to be invasive (i.e., spreading). Costs associated with Prosopis were perceived to exceed benefits, and most stakeholders wanted to see a reduction in the abundance of Prosopis stands. The mean total cost for the management of Prosopis was US$ 1914 year(-1) per farm, where costs ranged from under US$ 10 to over UD$ 500 per ha based on invasion densities and objectives for control. The findings highlight the need for more effective management interventions.

Prosopis: a global assessment of the biogeography, benefits, impacts and management of one of the world's worst woody invasive plant taxa

Invasive species cause ecological, economic and social impacts and are key drivers of global change. This is the case for the genus Prosopis (mesquite; Fabaceae) where several taxa are among the world's most damaging invasive species. Many contentious issues ('conflicts of interest') surround these taxa, and management interventions have not yet sustainably reduced the negative impacts. There is an urgent need to better understand the factors that drive invasions and shape management actions, and to compare the effectiveness of different management approaches. This paper presents a global review of Prosopis, focusing on its distribution, impacts, benefits and approaches to management. Prosopis was found to occur in a 129 countries globally and many more countries are climatically suitable. All areas with naturalized or invasive Prosopis species at present are suitable for more taxa and many Asian and Mediterranean countries with no records of Prosopis are bioclimatically suitable. Several Prosopis species have substantial impacts on biodiversity, ecosystem services, and local and regional economies in their native and even more so in their invasive ranges; others provide multiple benefits to local communities. Management efforts are underway in only a small part of the invaded range. Countries where more research has been done are more likely to implement formal management than those where little published research is available. Management strategies differ among countries; developed nations use mainly mechanical and chemical control whereas developing nations tend to apply control through utilization approaches. A range of countries are also using biological control. Key gaps in knowledge and promising options for management are highlighted.