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Global distribution of Leucaena leucocephala; sourced from the Invasive Species Compendium (CABI 2018). Individual points are representative of either a region, jurisdiction, country or continent. For example, this map shows that in Australia, leucaena is present in Queensland, New South Wales, The Northern Territory and Western Australia, but does not give specific locations of all known infestations.
Source publication
Keynote paper presented at the International Leucaena Conference, 1‒3 November 2018, Brisbane, Queensland, Australia.
Leucaena (Leucaena leucocephala) is widely recognized in many countries as a commercially valuable plant, particularly when used as a nutritious fodder in subtropical and tropical regions. However, it is also considered an environm...
Context in source publication
Context 1
... the native distribution of leucaena (i.e. Mexico and Central America) is relatively restricted on a global scale, a combination of deliberate and non-deliberate dispersal has led to it becoming one of the more widely naturalized species around the world ( Figure 1). In a comprehensive review of the pest status of leucaena, Walton (2003a) suggested that it could be naturalized in more than 105 countries throughout the world's subtropics and tropics. ...
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Navua sedge (Cyperus aromaticus) is threatening crops, pasture species and natural ecosystems in Pacific Island countries and northern Queensland, Australia. To aid future management efforts of this exotic invasive weed, research was conducted to understand the soil seed bank dynamics of pastures invaded by Navua sedge. Six grazing properties were...
Citations
... Therefore, the objectives of this research were to compare the application parameters and efficacy of RHS treatment with aminopyralid and aminocyclopyrachlor to basal bark and cut stump treatment with triclopyr or a girdle þ spray treatment with glyphosate and imazapyr on six woody invasive species. (Bruce et al. 1997;Minogue 2019;Rinehart et al. 2015;Snow 2013), agroforestry (Sharma et al. 2022), horticulture (Morton 1984), windbreaks and soil stabilization (Morton 1980), and other uses (Campbell et al. 2019). All have become invasive in Florida and are now classified as Category I or II species by the Florida Invasive Species Council and have suspected or documented negative ecosystem impacts (FISC 2023;Lemmens et al. 1995;Morton 1984;Vogt et al. 2021). ...
Reduced hack and squirt (RHS) is an herbicide injection technique that controls woody species with a limited number of hacks. When used with aminopyralid or aminocyclopyrachlor, the technique controls multi-stem shrubs such as Schinus terebinthifolia Raddi and Eugenia uniflora L. However, additional data is needed to compare its effectiveness on other woody invasive species against standard individual plant treatment techniques. We compared RHS with aminocyclopyrachlor or aminopyralid administered with 0.5 ml of undiluted concentrate (240 g L ⁻¹ ) against traditional basal bark and cut stump techniques using triclopyr at 96 and 120 g L ⁻¹ respectively, on six invasive trees in Florida, USA. For all species tested, the RHS technique with aminocyclopyrachlor was not different or was more effective than basal bark or cut stump treatment with triclopyr. The RHS technique with aminopyralid was effective on certain species but did not control as many species as RHS with aminocyclopyrachlor or cut stump treatment with triclopyr. The RHS technique required significantly less time than cut stump treatment but was not different than basal bark treatment. Across all species, when compared to basal bark and cut stump treatment with triclopyr, the RHS approach resulted in reductions of average total herbicide mix applied by 98 and 89%, respectively. For herbicide active ingredient, when compared to basal bark and cut stump treatment with triclopyr, RHS resulted in reductions of 95 and 86%, respectively. These results indicate that when compared to conventional individual plant treatment (IPT) approaches with triclopyr, the RHS approach yielded a high level of target efficacy on a broad spectrum of species, comparable or shorter application times, and substantial reductions in herbicide mix and active ingredient applied. Future research should seek a continued refinement of this technique for woody plant control on other troublesome invaders.
... Leucaena leucocephala (Lamarck) de Wit is a shrub or tree plant belonging to the family Fabaceae. It is an invasive exotic plant in many countries (Campbell et al., 2019), as in Brazil, and recently, it has been described as having an allelopathic potential (Kato-Noguchi & Kurniadie, 2022). This potential can be harmful in agroecosystems, reforested urban areas, or even in natural environments, where populations of L. leucocephala can reduce the abundance of other plants with economic and/or native purposes (Mauli et al., 2009). ...
Leucaena leucocephala is a forage legume that provides cellulose, firewood, and shade in cities, although it presents a dangerous allelopathic and invasive potential. Its main natural enemy is the endophytic beetle Acanthoscelides macrophthalmus (Chrysomelidae: Bruchinae), whose larvae penetrate seeds and can consume the entire endosperm and embryos. However, there is much to explore on how the abundance of larvae inside the seed affects the plant germination, resulting in an antagonistic (predation) or mutualistic (facilitation) interaction. Our goal was to test how these beetles affect the germination of L. leucocephala seeds from an urban environment in Uberlândia, MG. We hypothesized that a single larva inside the seed facilitates germination since the exit holes left break the physical dormancy and enable water imbibition. On the other hand, two or more larvae inside the same seed result in predation, as the amount of endosperm is not enough for beetle satiation before they attack the seed embryo. We collected 100 pods, dissected them, and quantified and qualified the seeds. In the germination experiment, we used healthy seeds (control), scarified healthy seeds (physical treatment), and attacked seeds (one, two, or more larvae). We found that beetles infested 74% of the sampled seeds. Independently of the abundance of larvae inside the seed, attacked seeds did not germinate. The scarified seeds germinate faster and in greater quantity. Therefore, our hypothesis was rejected for the studied plant population. Acanthoscelides macrophthalmus acts only as a predator in an antagonistic interaction that decreases the germination rate of L. leucocephala.
... L. leucocephala is regulated as an invasive weed in over 50 countries [7], and in northern Western Australia, its use is constrained by its weediness status [8]. ...
Leucaena is a versatile legume shrub/tree used as tropical livestock forage and in timber industries, but it is considered a high environmental weed risk due to its prolific seed production and broad environmental adaptation. Interspecific crossings between Leucaena species have been used to create non-flowering or sterile triploids that can display reduced weediness and other desirable traits for broad use in forest and agricultural settings. However, assessing the success of the hybridisation process before evaluating the sterility of putative hybrids in the target environment is advisable. Here, RNA sequencing was used to develop breeding markers for hybrid parental identification in Leucaena. RNA-seq was carried out on 20 diploid and one tetraploid Leucaena taxa, and transcriptome-wide unique genetic variants were identified relative to a L. trichandra draft genome. Over 16 million single-nucleotide polymorphisms (SNPs) and 0.8 million insertions and deletions (indels) were mapped. These sequence variations can differentiate all species of Leucaena from one another, and a core set of about 75,000 variants can be genetically mapped and transformed into genotyping arrays/chips for the conduction of population genetics, diversity assessment, and genome-wide association studies in Leucaena. For genetic fingerprinting, more than 1500 variants with even allele frequencies (0.4–0.6) among all species were filtered out for marker development and testing in planta. Notably, SNPs were preferable for future testing as they were more accurate and displayed higher transferability within the genus than indels. Hybridity testing of ca. 3300 putative progenies using SNP markers was also more reliable and highly consistent with the field observations. The developed markers pave the way for rapid, accurate, and cost-effective diversity assessments, variety identification and breeding selection in Leucaena.
... Já a porcentagem de sementes com defeitos por fruto coletado e que foram descartadas variou desde 0 até 76,92 % (Tabela 1). A alta taxa de produção de sementes e a capacidade das mesmas permanecem viáveis no solo por mais de 10 anos (Marques et al., 2014, Campbell et al., 2019 têm sido relacionadas à tendência invasiva da L. leucocephala (Costa et al., 2015, Drumond;Ribaski, 2010). Segundo Marques et al. (2014), essas características biológicas indicam o potencial da espécie para ocupar rapidamente ambientes alterados e manter substanciais bancos de sementes que garantirão a continuidade de suas populações. ...
A degradação ambiental no Pantanal tem favorecido a propagação da Leucaena leucocephala. Neste trabalho objetivou-se avaliar como o choque térmico afeta a qualidade fisiológica de sementes, intactas e escarificadas, posicionadas em diferentes profundidades no solo. Frutos e sementes coletados foram avaliados morfologicamente. Sementes foram submetidas aos testes de germinação e viabilidade. Sementes intactas e escarificadas foram aquecidas tanto na superfície do solo quanto enterradas. Observou-se que a espécie produz elevado número de sementes viáveis, que apresentam maior porcentagem de germinação quando escarificadas e, dentre essas, aquelas aquecidas quando enterradas, exibem maior porcentagem e velocidade de germinação.
... For example, some species of the genus Prosopis, native to the Americas, have been declared invasive in several regions of Africa and tropical Asia, although its presence has also been reported on the Australian continent and islands in the Pacific Ocean (Al-Assaf et al. 2020). The species Mikania micrantha has only been reported as invasive in the humid tropics of the Pacific and Asian countries, including India (Banerjee et al. 2017); however, species such as Psidium cattleianum, Chromolaena odorata, Lantana camara, and Leucaena leucocephala have a wider distribution, as they are reported to be invasive in Australia, Africa, and Pacific Ocean islands (Medeiros 2004;Mandal and Joshi 2014a, b;Dhami 2018;Campbell et al. 2019). ...
... It has been shown that, depending on the type of management strategy used to control invasive woody species, the impact on soil can be dramatic. For instance, use of bulldozers or excavators with mulching devices or the use of herbicides applied directly to the soil disturbs the treated area, altering its physical and chemical characteristics (Campbell et al. 2019;O'Brien et al. 2022). Other strategies are more polemics regarding its impacts. ...
... For example, some species of the genus Prosopis, native to the Americas, have been declared invasive in several regions of Africa and tropical Asia, although its presence has also been reported on the Australian continent and islands in the Pacific Ocean (Al-Assaf et al. 2020). The species Mikania micrantha has only been reported as invasive in the humid tropics of the Pacific and Asian countries, including India (Banerjee et al. 2017); however, species such as Psidium cattleianum, Chromolaena odorata, Lantana camara, and Leucaena leucocephala have a wider distribution, as they are reported to be invasive in Australia, Africa, and Pacific Ocean islands (Medeiros 2004;Mandal and Joshi 2014a, b;Dhami 2018;Campbell et al. 2019). ...
... It has been shown that, depending on the type of management strategy used to control invasive woody species, the impact on soil can be dramatic. For instance, use of bulldozers or excavators with mulching devices or the use of herbicides applied directly to the soil disturbs the treated area, altering its physical and chemical characteristics (Campbell et al. 2019;O'Brien et al. 2022). Other strategies are more polemics regarding its impacts. ...
The occurrence and spread of invasive woody species are a truly global phenomenon, but tropical regions seem to be particularly vulnerable due to high rates of soil degradation in combination with climate change, and limited resources for containment. There is increasing awareness that complete eradication programs are often not efective. The existence of many “controversial species,” i.e., species with both negative and positive impacts, renders decision-making processes for
management exceedingly complex. By providing a very extensive overview of the current state of knowledge on impacts and containment strategies of invasive woody species, we aim to help underpin such decisions. We discuss both negative impacts and potential benefts of invasive woody species, focusing on the two most important ones, namely animal fodder production and the positive impacts on soil functioning and soil quality. Invasive woody species can positively impact livestock
production (1) indirectly by improving pasture quality because of improved soil quality and functioning, and (2) directly by supplying a high-quality protein component for animal fodder. Invasive woody species increase soil carbon sequestration and nitrogen and phosphorus availability depending on the density of the invader, its capacity to fx nitrogen, the quantity and quality of its litter, and the direct interactions between its roots and the soil microbial community. The balance between potential benefts and risks depends to a large extent on the interaction with the local environment (climate, soil, vegetation, and animals) and the socioeconomic context of each region. When an invasion process starts because there is no local predator, then management can target eradication or very strict containment. If the invasion is the result of strong disturbance of the ecosystem, then intensive but well-thought management of the invasive species would be the choice to be made, as this may help to restore the ecosystem.
... While several species of leucaena have been used historically as minor foods in south-central Mexico (Hughes et al. 1995), Leucaena leucocephala (Lam.) de Wit. has been broadly adopted for use across the tropics, providing valuable forage (Takahashi and Ripperton 1949;Beutel et al. 2018), wood pulp (Khanna et al. 2019) and bioenergy (Haruthaithanasan et al. 2010;Tanavat et al. 2011). However, these introductions have come at a considerable cost to native ecosystems, with L. leucocephala becoming a notoriously invasive weed (Dadant 1953;Petty 1969;Campbell et al. 2019;Idol 2019). In Australia, a leucaena/grass pasture industry has been extensively utilised for decades in Queensland for cattle production (Buck et al. 2019;Shelton et al. 2021), but leucaena use in other states is constrained by its environmental weed status . ...
Context
The legume shrub/tree leucaena (Leucaena leucocephala (Lam.) de Wit.) is highly regarded as a cattle fodder, although it is considered an environmental weed in many parts of Australia.
Aims
We investigated the feasibility of developing a forage variety of triploid leucaena through interspecific hybridisation that is sterile (without seeds) as a strategy to mitigate its weed risk.
Methods
A conventional breeding strategy was used to create triploid hybrids from hand-crosses between tetraploid and diploid species of leucaena. Molecular markers were developed to confirm successful crosses and flow cytometry was used to confirm the ploidy level. The plants are being evaluated for flowering behaviour, seed and herbage production across two environmentally diverse sites at Carnarvon and Kununurra in northern Western Australia.
Key results
During 2018/19 and 2019/20, 2260 crosses between 45 different combinations of diploid females by tetraploid males and their reciprocals have created over 3000 putative triploid hybrid plants. This is the first time that triploids have successfully been created in Australia and 10 new parental combinations were created as a world-first.
Conclusions
A cohort of sterile triploid plants has been identified and selections will be made based on their edible biomass productivity, insect tolerance, capacity for regrowth after cutting, nutritive value and plant chemistry (including anti-methanogenic responses). A sterile leucaena variety will have application not only in Australian grazing systems but also in other tropical regions of the world.
Implications
A cost-effective technology for mass vegetative propagation of leucaena will be required for commercialisation of a sterile variety.
... Data from a Leucaena leucocephala (Lam.) de Wit. seed longevity trial was summarized in Campbell et al. (2019). They reported viable buried seed was still present (>4%) after eight years. ...
Longevity of weed seeds in the soil drives the cost and duration of weed control activities. Traditional methods for estimating weed seed longevity, such as repeated field soil sampling and buried packet trials can take many years and substantial resources to complete. A laboratory process, a Controlled Ageing Test (CAT) exposes seeds to and 'ageing environment' of 45 oC temperatures and 60% humidity. Data from this test is used to sort species into relatively transient, short lived or long-lived categories of weed seed longevity.
This paper reports on examples from a series of trials that seek to correlate the data from CAT batches with longevity data from buried packet trials.
... The species was also introduced to plantations in Indonesia, Papua New Guinea, Malaysia, and other counties of Southeast Asia. It was then taken to Hawaii, Australia, India, East West Africa, and Caribbean islands during the 19th century [3,11]. The distribution of the species has already expanded throughout the tropic and subtropics [1,2]. ...
... The life span of the species is relatively long (>30 years) and it produces a large number of seeds. These seeds are able to germinate after 10-20 years in good seedbank conditions, and after 1-5 years in hot and humid conditions [11,39]. Once L. leucocephala invades and establishes, the longevity of the plants and seedbanks may keep L. leucocephala stands for long time. ...
... L. leucocephala threatens native vegetations and biodiversity in the invaded areas [11,27,34]. The species richness in L. leucocephala invaded areas was lower than that in its unin- vaded areas, and the establishment of the native plant species was hardly observed in the L. leucocephala invaded areas [31,34,45,46]. ...
Leucaena leucocephala (Lam.) de Wit is native to southern Mexico and Central America and is now naturalized in more than 130 countries. The spread of L. leucocephala is probably due to its multipurpose use such as fodder, timber, paper pulp, shade trees, and soil amendment. However, the species is listed in the world's 100 worst invasive alien species, and an aggressive colonizer. It forms dense monospecific stands and threatens native plant communities, especially in oceanic islands. Phytotoxic chemical interactions such as allelopathy have been reported to play an important role in the invasion of several invasive plant species. Possible evidence for allelopathy of L. leucocephala has also been accumulated in the literature over 30 years. The extracts, leachates, root exudates, litter, decomposing residues, and rhizosphere soil of L. leucocephala increased the mortality and suppressed the germination and growth of several plant species, including weeds and woody plants. Those observations suggest that L. leucocephala is allelopathic and contains certain allelochemicals. Those allelochemicals may release into the rhizosphere soil during decomposition process of the plant residues and root exudation. Several putative allelochemicals such as phenolic acids, flavonoids, and mimosine were identified in L. leucocephala. The species produces a large amount of mimosine and accumulates it in almost all parts of the plants, including leaves, stems, seeds, flowers, roots, and root nodules. The concentrations of mimosine in these parts were 0.11 to 6.4% of their dry weight. Mimosine showed growth inhibitory activity against several plant species, including some woody plants and invasive plants. Mimosine blocked cell division of protoplasts from Petunia hybrida hort. ex E. Vilm. between G1 and S phases, and disturbed the enzyme activity such as peroxidase, catalase, and IAA oxidase. Some of those identified compounds in L. leucocephala may be involved in its allelopathy. Therefore, the allelopathic property of L. leucocephala may support its invasive potential and formation of dense monospecific stands. However, the concentrations of mimosine, phenolic acids, and flavonoids in the vicinity of L. leucocephala, including its rhizosphere soil, have not yet been reported.
... Its presence has been recorded in the 28 of 30 Oceanic Islands surveyed by Kueffer et al. (2010). However, as far as its invasion status is concerned, it is not regarded as invasive in every country it has been introduced to, as some categorize it as "contentious" (Clarkson et al., 2010;Campbell et al., 2019). On the contrary, several other countries consider it an aggressive invasive species of the tropical and subtropical regions (Richardson and Rejmánek, 2011). ...
... Leucaena suppresses the growth of resident woody species and understory vegetation, thereby reducing species diversity and richness. It has been reported to form thickets or monospecific stands that threaten the rare and endemic plant species (Costa et al., 2015;Campbell et al., 2019). A field study by Jurado et al. (1998) has proven the harmful effect of leucaena plantation on the seedling establishment of resident species. ...
... glabrata may provide better options for animal feed production, agroforestry, and the development of other industrial products without being a threat to the native plant diversity. Though ssp. glabrata has not been reported invasive up till now, a few studies suggest that it has the potential to become invasive in the future (Olckers, 2011;Campbell et al., 2019). It is important to ensure that ssp. ...
Leucaena leucocephala (Lam.) de Wit (commonly known as leucaena) is a leguminous species of the family Fabaceae and a native of Mexico and Central America. It is often addressed as a “miracle tree” for offering a wide variety of ecosystem services and possessing strong ecological attributes. The multiple uses of leucaena in agroforestry, livestock, and restoration practices led to the worldwide distribution of its ssp. glabrata and leucocephala. However, following its introduction into non-native regions, the commercial value of ssp. leucocephala was challenged by its large-scale spread outside the cultivation zone. It has assumed a status of an environmental weed and invasive plant in many regions across Africa (17 countries and Island nations), Asia (17), Europe (1), Oceania (23), North America (12), and South America (7). The plant is enlisted in the top five terrestrial invasive plant species with the greatest international presence. The species is now considered one of the 100 worst invaders in the world. The plant mainly invades roadsides, wastelands, cultivated lands, riverbanks, and forest edges, and suppresses the growth of other woody and herbaceous species. Its infestations alter the patterns of vegetation, plant succession, and community assembly in the introduced habitats. Propagation of ssp. leucocephala, without considering the environmental risks associated with it, may result in major repercussions and irreparable losses. Therefore, it is important to discuss its invasive propensities and the possible alternatives that may replace the weedy species without encumbering its economic benefits. This review aims to thoroughly evaluate the ecological and invasive attributes of leucaena, promote awareness about the ecological costs associated with its spread, and suggest suitable options for its management.
