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Effectiveness of conservation areas in protecting Shea trees against hemiparasitic plants (Loranthaceae) in Benin, West Africa

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Background and aims – The Shea tree (Vitellaria paradoxa), a multi-purpose species highly valued for the oil obtained from its seeds, is commonly maintained in the semi-arid parklands in West African Sudanian zone. However, most of the trees were reported to be infested with mistletoes – plant parasites that may lead to death of the Shea tree and these parasites are known to be directly dispersed on their host by birds. This study therefore aimed to assess the potential effectiveness of protected area on preventing mistletoes proliferation on Shea tree individuals. Methods – Infestations in two habitats: land use area (fields and fallows) and protected area of Pendjari hunting zone were compared. Overall 54 plots of 1 ha (100 m × 100 m) with 487 and 252 individuals of Shea tree in land use and protected area respectively were investigated. ANOVA was used to compare Shea tree infestation rate and infestation degree (with regard to diameter and height of infested Shea tree). Principal Component Analysis (PCA) was performed to correlate the habitats with infestation degree. Key results – The results showed that about 80% of Shea tree individuals were infested in the land use area, this rate was significantly higher than the one of 27.3% observed in the protected area. Overall, heavily infested Shea trees had significantly larger trunks and heights, mainly in land use areas. The land use area was shown to be correlated with high and very high Shea tree infestation degrees while the others infestations degrees (very weak, weak and moderate) were correlated with both areas. Conclusions – Shea trees growing in protected areas are better protected against mistletoe plant parasites than those on cultivated land. Various hypotheses to explain this result are discussed.
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... Ces parasites sans être spécifiques au karité, ont trouvé en lui un hôte favorable (Soro, 1999). Ces hémiparasites, une fois implantés sur leurs hôtes affaiblissent ces derniers, réduisent de façon drastique leur productivité fruitière et menacent leur statut de conservation (Houéhanou et al., 2011 ;Edagbo et al., 2013). Cette attaque du karité par les Loranthaceae a été déjà signalée au Burkina Faso où 95 % des individus sont parasités (Boussim et al., 1993). ...
... Les paramètres utilisés sont le taux d'infestation et la densité parasitaire. Le taux d'infestation (Ti) tel qu'utilisé par Houéhanou et al. (2011), nous a permis d'exprimer la proportion des pieds de karités parasités dans les zones. Il s'exprime en pourcentage et se calcule par la formule suivante : ...
... Les résultats ont montré que la densité parasitaire des pieds de karité augmente au fur et à mesure que leur dbh croît. Ces résultats sont similaires à ceux obtenus par Houéhanou et al. (2011) sur le karité dans le parc national de la Pendjari, Ahamidé et al. (2015) sur Cola nitida au sud du pays et Edagbo et al. (2013) sur Irvingia gabonensis au Nigeria. Ceci est dû au fait que les arbres de plus gros diamètres sont probablement les plus âgés, les plus fréquentés par les oiseaux car, ils offrent une plus grande sécurité face aux rapaces (Traoré et al., 2003). ...
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Shea butter: Vitellaria paradoxa C. F. Gaertn (Sapotaceae) is a fruit tree in the Sudano-Sahelian region where it is a major economic source. Unfortunately, in Benin, the species has been revealed in recent decades, the target of parasitic vascular plants of Loranthaceae family that threaten its conservation. The present study, carried out in northern Benin, evaluated the impact of these parasitic plants on the shea of two phytogeographical zones. The botanical inventory identified three species of Loranthaceae in fields and protected areas. The rate of infestation and parasite density were assessed and their variation on shea was assessed. The results show that shea is parasitized by three species of Loranthaceae in varying proportions: Agelanthus dodoneifolius (DC.) Polh. and Wiens (191.75 tufts / ha), Tapinanthus globiferus (A. Rich.) Van Tieghem (70.57 tufts / ha) and T. Ophiodes (Sprague) (2 tufts / ha). The impact of Loranthaceae on shea productivity varies significantly between fields and protected areas with infestation rates of 87% versus 42% and average densities per shea foot of 14.76 tufts versus 3.62 tufts. These results are data to be taken into account in the control programs against Loranthaceae which parasitize shea.
... The role of protected areas in the prevention of extinction of species has been much debated (Bruner et al., 2001). Several studies focused on the effectiveness of the protected areas to ensure the representativeness and persistence of biodiversity components (Defries et al., 2005;Wittemyer et al., 2008;Houéhanou et al., 2011Houéhanou et al., , 2012Houéhanou et al., , 2013. Some of the studies (Djossa et al., 2008;Gouwakinnou et al., 2009;Schumann From the demographic explosion, correspondingly strong land modification was observed in West Africa (Wittig et al., 2007;Wittemyer et al., 2008). ...
... It conserves 28% of the total flora of Benin Republic (Assédé et al., 2012). Previous studies have highlighted the importance of this reserve in plant conservation (Gouwakinnou et al., 2009;Fandohan et al., 2011;Houéhanou et al., 2011Houéhanou et al., , 2013. Although the BRP is assumed to be the best way to conserve biodiversity of this area, its effectiveness in future conservation of several plant species is not always guaranteed (Houéhanou et al., 2013). ...
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The effectiveness of protected areas to guarantee future conservation of several plant species remains questionable. This study was carried out in the Biosphere Reserve of Pendjari (BRP) and surrounding unprotected areas to assess the efficiency of the reserve to conserve orchids. A total of 90 plots (52 in protected areas; 38 in unprotected areas) were sampled. The recorded data include: orchid species, number of individuals per species, the height and diameter at breast height of host trees. Diversity indices were used to assess the orchid diversity in the protected and unprotected areas. Preferred habitat conditions of orchid species were investigated using Constrained Correspondence Analysis. An independent t-test and two-way analysis of variance were performed to assess an existing combined effect of vegetation type and the conservation status on the density of orchid species. The Importance Value Index (IVI) was used to measure how dominant an orchid species is in a given zone according to the conservation status of the zone. Only three epiphytic orchids (Calyptrochilum christyanum, Cyrtorchis arcuata and Plectrelminthus caudatus) were recorded and all in gallery forest of unprotected areas. Indeed, 67% and 58% of the orchid species were only recorded in unprotected areas and in gallery forest, respectively. There was no significant difference between the density of all recorded orchids in protected and unprotected areas. The conservation status of the studied zone had a significant effect on the densities of Nervilia kotschyi and Eulophia guineensis (p < 0.0001). The highest IVI of N. kostchyi was observed in the protected area and of E. guineensis was in the unprotected area. This first effort to compile a reference list of the orchid species of the BRP showed that some orchid species were well represented within the protected area, but all of the epiphytic orchids were recorded from unprotected areas. A representative gap can be assumed to exist for most epiphytic orchids only recorded in the gallery forests of unprotected areas. Our results highlighted the need to redefine protective management strategies for orchid species in the BRP.
... Tapinanthus species) commonly referred to as mistletoe is pervasive throughout sub-Saharan Africa. Other studies have found that 80-95% of shea trees are infected with this vine (Houehanou et al. 2011;Lamien et al. 2006;Odebiyi et al. 2004) though one study in Burkina Faso recorded the amount of flowering and fruiting on 46 shea tree limbs infected with mistletoe to 46 limbs uninfected and did not find a significant difference (Lamien et al. 2006). However, the control, or uninfected limbs, were on a tree that had mistletoe in other areas. ...
... Before implementation of pest management interventions, consultation of male and female farmers and women collectors in their management of the pest species is imperative and evaluation of the potential risk of pest interventions on the shea tree population must be conducted. Furthermore, shea trees may be more vulnerable to pests as their resilience is compromised by decreased rainfall (Houehanou et al. 2011). ...
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Shea butter, an edible oil and lotion produced primarily by women in over twenty-one countries in sub-Saharan Africa and consumed locally and exported internationally, can contribute considerably to achievement of several United Nations Sustainable Development Goals. This study investigated the importance of shea butter to women and their families for food security, household economy, women’s empowerment, and social capital. It highlights the vital social value of shea butter in cooperative labor for production, gifting customs among women, and traditional and religious ceremonies. In addition, this study identifies critical opportunities for and obstacles to further market expansion. Based on a mixed methods approach employed in Mali from 2009 to 2014, this study included participant observation, interviews, surveys, and focus group discussions as well as shea tree mapping and weighing of shea and firewood. Major challenges that exist for shea market expansion and food security potential include climate change and globalization of other competing world edible oils. Nevertheless, there are promising opportunities for the shea market with the extensive shea tree distribution, growth of consumer support for environmentally and socially conscious products, and capacity building efforts of rural shea nut collectors and butter producers by the Global Shea Alliance.
... Le taux d'infestation de 53% signalé dans la présente étude est similaire à celui de 52,63% enregistré sur le safourtier (Dacryodes edulis) au Cameroun (Massako et al., 2013) mais inférieur aux taux de 80% et 59,87% respectivement signalés sur Vitellaria paradoxa (Houéhanou et al., 2011) et sur les agrumes au Bénin (Houénon, 2012). Ces variations trouveraient leur origine dans la différence de sensibilité des hôtes et les conditions écologiques. ...
... Ces variations trouveraient leur origine dans la différence de sensibilité des hôtes et les conditions écologiques. Toutefois, la présence d'autres espèces à proximité de C. nitida dans les jardins de case et dans les plantations de la zone d'étude justifie ce faible taux par rapport à celui observé par Houéhanou et al. (2011) pour Vitellaria paradoxa dans les champs environnant le parc de la Pendjari au nord-Bénin, où la diversité en fruitier est faible. En effet, en cas de diversité d'hôtes élevée, les oiseaux ont la possibilité de déposer les graines de Loranthaceae sur d'autres hôtes que ceux ciblés. ...
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Cola nitida est une espèce fruitière à usages multiples qui, malheureusement, est souvent la cible des plantes parasites de la famille des Loranthaceae. L’objectif de la présente étude est de recenser les espèces de Loranthaceae parasites de C. nitida, d’évaluer leur impact sur ce fruitier et d’inventorier les usages thérapeutiques faits de ces plantes parasites au Sud du Bénin. Pour y parvenir, des inventaires floristique et forestier puis des enquêtes ethnobotaniques ont été réalisés. Au total, 15 plantations et 50 jardins de case abritant C. nitida ont été explorés dans 12 villages à travers lesquels 87 personnes utilisant les Loranthaceae ont été questionnées. Les résultats révèlent que sur les 552 pieds de C. nitida explorés, 6 espèces de Loranthaceae qui sont : Globimetula braunii, G. cupulata, Phragmanthera capitata, Tapinanthus bangwensis, T. belvisii et T. globiferus ont été recensées. Le taux d’infestation est de 53%. Sur le plan ethnobotanique, les Loranthaceae de C. nitida interviennent dans le traitement de 3 affections que sont : la stérilité, les fausses couches (40% chacune) et les troubles menstruels (20%). Cette étude permet de proposer l’utilisation à grande échelle des Loranthaceae comme approche de gestion durable de ces hémiparasites.© 2015 International Formulae Group. All rights reserved.Mots clés: Gui africain, biodiversité, densité parasitaire, gestion durable, BéninEnglish Title: Diversity, impacts and uses of Loranthaceae growing on Cola nitida (Vent.) Schott. & Endl. in Southern BeninEnglish AbstractCola nitida is a kind of fruit presenting international multiple uses. However, this fruit is often the target of parasitic plants of Loranthaceae family. The aim of the present work is to know the diversity and impact of Loranthaceae on C. nitida tree and the different uses made of these parasites. A total of 552 feet of C. nitida have been explored within 15 plantations and 50 home gardens spread in 12 villages through which 87 people using Loranthaceae have been questioned. The results show that C. nitida is parasitized by 6 species of Loranthaceae (Globimetula braunii, G. cupulata, Phragmanthera capitata, Tapinanthus bangwensis, T. belvisii and T. globiferus). Infestation rate of C. nitida is 53%. On ethnobotanical level, Loranthaceae growing on C. nitida contribute to the treatment of three diseases which are barrenness, miscarriage (40% each) and menstrual disorders (20%). Pending the development of effective struggle methods against Loranthaceae growing on C. nitida, the widespread use of these parasites can contribute to maintain them in acceptable damage threshold and also generate incomes for people.© 2015 International Formulae Group. All rights reserved.
... The average parasitic density (APd) was calculated by dividing Pd by the total number of parasitized trees (Np). APd = Pd / Np [12];  Mortality rate (Mr) corresponds to the ratio of the number of died tufts (Ndt) to the total number of tufts of an individual (Pd). Mr (%) = Ntd / Pd x 100 [9]. ...
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Citrus farming is currently a main sector in Africa in general, particularly in the sub-Saharan region. Citrus farming in Cameroon has been expanding since the cocoa crisis and thanks to its financial and economic benefits. The research aim was to evaluate the parasitism of Loranthaceae on citrus trees in the Mongo department. Direct observations were made in the canopy of 796 citrus trees in seven arrondissements, and included species identification, and the Loranthaceae species growing on their foliage. Alive and dead tufts were numbered to estimate parasitism density and mortality rate. Five species of Loranthaceae identified on six citrus species. Tapinanthus predominated with three species, T. bangwensis T. preussii and Tapinanthus sp. Phragmanthera capitata was the most frequent (75.37%), and T. preussii was scattered (2.33%). The highest mean parasitic density was obtained in T. bangwensis has the higher parasitic density (5.76±5.17 tufts/tree), followed by Helixanthera mannii (5.42±4.13 tufts/tree). The highest rate of parasitism was obtained on C. maxima (89.77%), and the highest natural mortality rate of Loranthaceae was on C. medica (12.5%). Loranthaceae have already greatly expanded in Citrus, it recommended to set up a monitoring system to protect the yields.
... De plus, la présence des activités anthropiques dans les parcs agroforestiers aurait contribué à réduire significativement la richesse spécifique. En effet, selon Bouko et al. [31], la faible richesse spécifique dans certains espaces cultivés résulte des défrichements agricoles intensifs, l'exploitation pour le fourrage, l'exploitation du bois d'oeuvre et du boisénergie et la production du charbon du bois. Néanmoins, les parcs agroforestiers de Dindéresso et de Kuinima sont floristiquement plus riches que ceux de Dan Mairo et de Sarkin Yamma [26]. ...
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Les parcs agroforestiers occupent des superficies non négligeables au Burkina Faso. Mais, du fait de la pression foncière, ils subissent des formes d’exploitation qui menacent leur existence dans le moyen terme. Pour une gestion durable des parcs agroforestiers, leur connaissance sur le plan floristique s’impose. C’est ainsi qu’une étude floristique a été menée dans les parcs agroforestiers des forêts classées de Dindéresso et de Kuinima à l’Ouest du Burkina Faso. L’objectif est de contribuer à une meilleure gestion du peuplement ligneux des parcs agroforestiers. Pour ce faire, un inventaire forestier dans des placettes circulaires de 900 m² a été réalisé en vue d’établir la liste floristique, la diversité spécifique et d’apprécier l’état de la régénération et l’état sanitaire des peuplements ligneux. Au total, 27 espèces ligneuses réparties en 14 familles et 27 genres dans les parcs agroforestiers de Dindéresso et 27 espèces ligneuses réparties en 12 familles et 26 genres dans les parcs agroforestiers de Kuinima ont été inventoriées. La diversité spécifique de Shannon-Weaver est faible avec 1,80 bit pour les parcs agroforestiers de Dindéresso et 1,33 bit pour ceux de Kuinima. La régénération est beaucoup plus marquée par l’espèce Vitellaria paradoxa Gaertn.f. suivie de Anacardium occidentaleL. [cult.]. Les taux de régénération sont de l’ordre de 54,12% et 9,41% pour Dindéresso puis 35,64% et 26,60% pour Kuinima respectivement, pour Vitellaria paradoxa et Anacardium occidentale. L’appréciation de l’état sanitaire révèle que 49,85% des pieds de Vitellaria paradoxa inventoriés dans la forêt classée de Kuinima sont parasités. Par contre dans la forêt classée de Dindéresso, le taux de parasitisme des pieds de Vitellaria paradoxa est de 13,37%. Au regard de ces taux de parasitisme, il est plus que nécessaire de développer des stratégies de lutte contre ces plantes parasites. À court et moyen termes si rien n’est fait, ces parasites affecteront considérablement les capacités de cette espèce agroforestière à fournir des biens et services.
... Caterpillars (Cirina forda) (Westwood 1849) and stemborers (Neoplocaedaerus sp) (N'Djolossè et al. 2012) primarily defoliate new leaves of shea trees, affecting all stages of the shea tree growth cycle, from seedlings to mature trees. Parasites like plants of the genus Tapinanthus (Boussim et al. 1993) and mistletoe (Loranthaceae) (Houehanou et al. 2011) heavily infest the trees, though at higher intensities in parklands compared to protected areas. In addition, larvae of Mussidia nigrivenella Ragonot 1888 and the Oriental fruit fly Ceratitis silvestrii Bezzi 1912 also affect mature shea trees by feeding on the pulp (Okiror et al. 2012). ...
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Ecosystems degradation, and consequently biodiversity loss, has severe impacts on people around the world. The Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES) is one of the international initiatives that have emerged to inform policy makers and aid decisions to prevent further global biodiversity loss, focusing on the interdependence between natural systems and human culture. IPBES promotes the use of scenarios and modelling approaches as a fundamental tool to advance the understanding of the relationships between drivers of change, Nature's Contributions to People (NCP), and social systems. Local-scale case studies with a system approach demonstrating how current knowledge can be used to inform decision-making are still scarce. Here, we present a comprehensive conceptual model and a series of four scenarios under different policies for shea tree species management, as a case-study of applying systems thinking and the NCP concept to a local-scale socio-ecological system. We first characterized the central processes, NCP, drivers and pressures affecting the shea tree system, to investigate the impacts of the multiple uses of the shea tree species on the system as a whole. We then described potential policy options, developed four scenarios, and evaluated them by a Bayesian Belief Network (BBN). We predicted qualitative outcomes of the proposed scenarios: Business-as-usual (BAU), "Conservation and fair trade", "Agroforestry and fair trade" and "Industrial development". We found that the scenarios focussing on conservation, fair trade and agroforestry, can improve the conservation status of shea trees, and enhance wellbeing in the local communities. In this case study, we demonstrate that the development of a comprehensive conceptual model at a local scale can be a useful exercise to identify opportunities for effective policy strategies and social innovation. The shea tree case study can provide an example for modelling non-timber forest products in other regions around the world that face similar drivers and pressures. Species for which this model could be adapted include Central and South American species such as the Brazilian nut (Bertholletia excelsa), cocoa (Theobroma cacao), andiroba (Carapa guianensis), açai (Euterpe oleracea) and the wax palm (Ceroxylon quindiuense). The model and workflow applied here may thus be used to understand similar socio-ecological systems with local and international economic value across the Neotropical region. Modelagem de cenários para o manejo sustentável de produtos florestais não-madeireiros em ecossistemas tropicais Resumo: A degradação dos ecossistemas e sua consequente perda de biodiversidade apresentam graves impactos sobre as pessoas em todo o mundo. A Plataforma Intergovernamental de Biodiversidade e Serviços Ecossistêmicos (IPBES) é uma das iniciativas internacionais que surgiram para informar tomadores de decisão e o desenvolvimento de políticas para evitar mais perdas globais de biodiversidade, com foco na interdependência entre sistemas naturais e a cultura humana. O IPBES promove o uso de cenários futuros e abordagens de modelagem como uma ferramenta fundamental para avançar no entendimento das relações entre fatores motivadores de mudança (vetores), as Contribuições da Natureza para as Pessoas (NCP) e sistemas sociais. Estudos de caso em escala local com uma abordagem de sistemas mostrando como o conhecimento atual pode ser usado para informar a tomada de decisão ainda são poucos. Neste trabalho, apresentamos um modelo conceitual abrangente e um conjunto de quatro cenários sob diferentes políticas para o manejo da árvore de karité, como estudo de caso para a aplicação de uma abordagem de sistemas e do conceito de NCP em um sistema socioecológico em escala local. Primeiro nós caracterizamos os processos centrais, os NCP, e os vetores e pressões que afetam o sistema da árvore de karité, para então, investigar os impactos dos múltiplos usos da espécie no sistema como um todo. Em seguida, descrevemos opções de políticas possíveis, a partir das quais desenvolvemos quatro cenários e os avaliamos por Redes Bayesianas baseadas em Crenças (BBN). Nós avaliamos os resultados qualitativos dos quatro cenários de manejo propostos: "business-as-usual" (BAU), "Conservação e Fair Trade", "Agrofloresta e Fair Trade", e "Desenvolvimento Agroindustrial". Verificamos que os cenários que incluíam medidas de conservação e comércio justo, assim como o que previa práticas agroflorestais indicaram potenciais melhorias no status de conservação das árvores de karité e aprimoramento do bem-estar das comunidades locais. Neste estudo de caso, demonstramos que o desenvolvimento de um modelo conceitual mais completo na escala local pode ser útil na identificação de oportunidades para a proposição de estratégias políticas efetivas e inovação social. O estudo de caso da árvore de karité pode fornecer um exemplo de modelagem de produtos florestais não-madeireiros para outras regiões do mundo que enfrentam vetores de mudança e pressões semelhantes. As espécies para as quais esse modelo pode ser adaptado incluem espécies da América Central e do Sul, como a castanha-do-brasil (Bertholletia excelsa), cacau (Theobroma cacao), andiroba (Carapa guianensis), açaí (Euterpe oleracea) e a palma da cera (Ceroxylon quindiuense). O modelo e a proposta de trabalho aplicados aqui podem, portanto, ser usados para entender sistemas socio-ecológicos semelhantes com espécies de valor econômico local e internacional em toda a região neotropical.
... During dry seasons, WEP help mitigate hunger (Leakey 2001;Assogbadjo et al. 2008;Phounvisouk et al. 2013). Moreover, WEP constitute the first source of medicine for more than 80% of rural populations (Houéhanou et al. 2011). Becker and Ghimire (2003) demonstrated through a literature review that the rural communities' knowledge and norms offer opportunities for WEP conservation and preservation. ...
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Cola nitida is a West African tree, commonly used for pharmaceutical purposes. In Benin, the species is used for many purposes ranging from traditional rituals to domestic consumption. Nowadays, the species, as well as its offspring, are hardly encountered. So far, research on the species focused on a single domain such as ethnobotany and phytochemistry. The current paper used a holistic approach to explain the species scarcity in the natural habitats using (1) the rural knowledge pattern on C. nitida and (2) the tree population structure. Semi-structured interviews (n = 170 respondents) were conducted and combined with ecological inventory (n = 38 plots) in the phyto-geographical districts of Coast and Pobè in southern Benin. The indices of diversity, equitability, and consensus quantified the range, the evenness, and the relative reliability of rural communities’ knowledge. Moreover, the plant part index gave the most used part of the tree. The knowledge on the species was unevenly distributed according to the gender, while the cofactor age did not have a statistically significant effect (P = 0.902) on the pattern. In addition, seeds represented the most used plant part (PPI = 0.59). C. nitida tree demographic structure showed a low density of seedling and sapling (1.05 ± 0.47 trees ha⁻¹). Diameter size fitted with a two-parameter Weibull distribution indicated a threat of species extinction. The multiple uses of C. nitida seeds do not allow natural regeneration of the species. The domestication of C. nitida tree and the establishment of Cola garden/orchard in the surveyed districts are suggested for sustainable use of the species.
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La présente étude vise à documenter l’utilisation des Loranthaceae en médecine traditionnelle humaine pour le développement de la santé. Les données ont été collectées de mars 2015 à février 2017 au Nord du Bénin par le biais d’enquêtes ethnobotaniques menées auprès de 240 répondants répartis en 15 ethnies. Ces données ont permis d’établir la liste des espèces de Loranthaceae et leurs hôtes utilisées en médecine traditionnelle humaine, de catégoriser les usages médicinaux des Loranthaceae et de calculer la contribution des parasites aux recettes. Au total, 4 espèces de Loranthaceae sont utilisées. Il s’agit d’Agelanthus dodoneifolius (61,6 %), Tapinanthus globiferus (37,5 %), Phragmanthera kamerunensis (0,8 %) et T. ophioides (0,1%). Elles sont récoltées sur 54 espèces-hôtes réparties en 50 genres et 19 familles. L’utilisation des Loranthaceae se fait sans distinction de l’espèce parasite mais plutôt en fonction de l’espèce-hôte. Ces parasites sont impliqués dans 69 usages médicinaux. Au regard de leur contribution moyenne aux recettes, les guis de Parkia biglobosa (15,5 %) et Vitellaria paradoxa (14,4 %) sont les plus utilisés. Ces résultats permettent d’envisager la valorisation des Loranthaceae à travers l’utilisation de ces parasites pour la fabrication de phytomédicaments. Cette stratégie de valorisation des Loranthaceae contribuera à l’essor de la santé au Bénin.
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A wildlife survey was carried out in Pendjari National Park of Benin in April 2000. The park covers an area of 2,660 km(2). Larger mammals were censused along 97 parallel line transects. The transects lay 1 km apart and were 15 km long on the average. The total length of strips (effort) was 1,455 km. Count data were analysed with the "Distance" programme. Twenty species were recorded during the survey, including most of the larger mammals of West Africa, in particular bovids. The most abundant species were olive baboons (Papio anubis), western buffalo (Syncerus caffer brachyceros) and kob (Kobus kob), with respective densities of 3.06, 1.0 and 0.98 animals/km(2). The total biomass of larger mammals was 0.63 t/km(2) (elephants: Loxodonta africana excluded) and 1.12 t/km(2) (elephants included). The carrying capacity for herbivores was estimated at 2.8 t/km(2). Except for buffalo, roan antelope (Hippotragus equinus) and hartebeest (Alcelaphus buselaphus major), both species richness and abundance were lower than in a previous survey ten years earlier, and species such as topi (Damaliscus lunatus korrigum) and leopard (Panthera pardus) were no longer detected. The results signify the need to revise and improve current wildlife conservation and management strategies to assure long-term protection of larger mammals in Pendjari National Park.
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Mistletoes are a polyphyletic group of approximately 1,400 species of obligate hemiparasites, distributed worldwide. While they obtain all of their minerals and water from their host (typically a tree or shrub), they are green plants that generally manufacture their own carbohydrates by photosynthesis. They maintain low water potentials relative to their hosts by concentrating soluble cations and organic compounds in their tissues, and typically have higher rates of transpiration than their hosts. They are pollinated primarily by birds, and birds are also the main vector for fruit dispersal. In addition to these mutualistic interactions, mistletoe is a popular food source for a wide variety of animals, often providing nutritional resources when little else is available. They are also highly favored roost and nest sites for a wide range of animals and are considered one of the main causes of hollow formation in many regions. Mistletoe can therefore be considered a keystone resource, having a disproportionate influence on the ecosystem as a whole, affecting distribution patterns of organisms both directly and indirectly. While some mistletoe species can have deleterious effects on their host, most mistletoes are best regarded as water-parasites, having a negligible effect on host survivorship. Given the range of interactions mistletoes have with pollinators, dispersers, herbivores, and hosts, they are a sensitive assay of environmental integrity and have been used as indicators of overall habitat health.
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The relationship between mistletoes and birds has been studied from the perspectives of mutualism and seed dispersal. Here, we emphasize the role that avian dispersers play as agents of mistletoe seed transmission to plant hosts. We describe the patterns of transmission of the seeds of Tristerix aphyllus, an endophytic Chilean mistletoe, on two of its columnar cacti hosts (Eulychnia acida and Echinopsis skottsbergii) by the Chilean Mockingbird Mimus thenca. In north-central Chile, these cacti grow in relatively discrete subpopulations on north-facing slopes. We measured variation in seed transmission within 10 subpopulations varying in species composition, host density, parasite density, parasite prevalence (defined as the percentage of hosts infested in a given population), and disperser abundance. Seed transmission was independent of species, but was strongly dependent on prior parasitism. Parasitized individuals received seeds much more frequently than expected from their relative abundance. We found no correlation between the density of hosts and seed transmission. We found strong positive correlations, however, between parasite prevalence and seed transmission to both parasitized and nonparasitized hosts. Seed transmission of T. aphyllus seeds by M. thenca appeared to be frequency-rather than density-dependent. Seed transmission was also tightly and positively correlated with the abundance of seed-dispersing birds at each site. Because bird abundance and parasite prevalence were correlated, we conducted path analysis to disentangle their relative effect on seed transmission. A model including only the direct effect of bird abundance and the indirect effect of parasite prevalence through bird abundance explained roughly the same variance as a full model including both the direct and indirect effects of bird abundance and prevalence on seed transmission. Apparently, variation in bird abundance was the main determinant of variation in transmission. We suggest that mistletoes, host plants, and the birds that disperse mistletoe seeds are systems well suited for studies of the ecological and evolutionary dynamics of disease transmission.
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The principal host of the mistletoe, Amyema preissii, near Alice Springs is the short-lived, fast-growing tree, Acacia victoriae. In order to describe the dynamics of their interaction, the fate, size and phenology of mistletoes were monitored in natural host stands, infection experiments were conducted to determine establishment success and growth rates of seedlings, hosts were repeatedly disinfected in a 14.6-ha paddock surrounded by infected source trees, and mistletoe reinvasion of disinfected trees was monitored. In the unmanipulated population of A. victoriae, 46–54% of trees (> 2 m in height) were infected (5.8–6.7 mistletoes per infected tree). Establishment percentage of mistletoe seeds deployed on host branches varied between 11–24% after 12–23 months, and most naturally-dispersed seedlings established on branches ≤ 20 mm in diameter. Estimates of natural mistletoe dispersal to uninfected trees varied between 2 and 12 seeds per infected tree over periods of 8–23 months. Examination of young mistletoes showed that 24% of 122 clumps consisted of more than one mistletoe, with 27 occurrences of double infection and two occurrences of triple infection at the same point on the host branch. Mistletoes grew rapidly: in one sown cohort, plants achieved canopy diameters of 152–170 cm within 18–23 months, and half were flowering 15 months after germination. In unmanipulated populations, the largest mistletoes had a maximum canopy diameter of 250 cm and a maximum host branch diameter proximal to the haustorium of 100 mm, but modal sizes of these measures were 80–120 cm and < 10 mm, respectively. Turnover in the host population in the disinfection paddock was rapid: 60% of trees died between 1990 and 1995, mortality being balanced by recruitment. In unmanipulated stands of host trees, larger trees were more likely to be infected and supported larger numbers of mistletoes per tree than small trees. Once mistletoes had been removed from trees in the disinfection paddock, larger trees were still disproportionately infected by reinvading mistletoes and trees that had been infected previously were more likely to be reinfected. In order to fully describe the spatial and temporal dynamics of this host–mistletoe combination, further studies are needed of mistletoe persistence and mortality through time and annual seed production as a function of mistletoe size.
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The endemic mistletoe, Ileostylus micrunrhus, growing in the Northern Cemetery (Dunedin, New Zealand), was examined with respect to both its OCCUrrenCe on different host species and its distribution on the trunk and within the canopy of its hosts. Only 3.5% of trees were infected and the mistletoe was absent from hosts with trunk diameters of more than 70 cm. The most frequently infected hosts were Erica Iiisitanica, Betula pendiifa, and Pittosporum tenuifofium. Larger hosts generally supported mOre mistletoe infections than smaller hosts. Most individual infections were small or medium‐sized. Mistletoe plants were distributed throughout the canopy of infected hosts but were least frequent on the trunk and most frequent in the middle and lower thirds of the canopy. Large mistletoes tended to be found more frequently on the outer parts of the canopy and on the trunk than juvenile, small, and medium‐sized mistletoes.