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Yaoundé, Cameroon

Famah Sourassou N.,International Institute Of Tropical Agriculture | Famah Sourassou N.,University of Amsterdam | Hanna R.,International Institute Of Tropical Agriculture | Hanna R.,Humid Forest Ecoregional Center | And 6 more authors.
Experimental and Applied Acarology

Predatory mites identified as Neoseiulus paspalivorus DeLeon (Phytoseiidae) have been considered as agents for classical biological control of the coconut mite, Aceria guerreronis Keifer (Eriophyidae), in Africa and elsewhere. Preliminary identification of geographically distinct populations as belonging to the same species (N. paspalivorus) was based on their morphological similarity. However, laboratory studies recently conducted have shown large differences in feeding behaviors and biological characteristics among individuals collected from three geographic origins: Brazil (South America), Benin and Ghana (West Africa). As morphologically similar specimens do not necessarily belong to the same species, we evaluated under laboratory conditions, reproductive compatibility between the specimens from three geographic locations to ascertain their conspecificity. Morphological measurements were also made to determine whether there is a means of discriminating between them. Inter-population crosses showed complete reproductive isolation between the three geographic populations, but interpopulation discontinuities in morphometric characters were absent. These results indicate that the tested specimens are distinct biological entities despite morphological similarity. Further molecular genetic studies are therefore proposed, including screening for endosymbionts and assessment of genetic differentiation, to determine the cause of reproductive incompatibility and to clarify the taxonomic relationship between those populations. © 2010 Springer Science+Business Media B.V. Source

Zandjanakou-Tachin M.,International Institute Of Tropical Agriculture | Zandjanakou-Tachin M.,University of Lome | Ojiambo P.S.,International Institute Of Tropical Agriculture | Ojiambo P.S.,North Carolina State University | And 4 more authors.
Plant Pathology

Mycosphaerella species that cause the 'Sigatoka disease complex' account for significant yield losses in banana and plantain worldwide. Disease surveys were conducted in the humid forest (HF) and derived savanna (DS) agroecological zones from 2004 to 2006 to determine the distribution of the disease and variation among Mycosphaerella species in Nigeria. Disease prevalence and severity were higher in the HF than in the DS zone, but significant (P<0·001) differences between agroecological zones were only observed for disease severity. A total of 85 isolates of M. fijiensis and 11 isolates of M. eumusae were collected during the survey and used to characterize the pathogenic structure of Mycosphaerella spp. using a putative host differential cultivar set consisting of Calcutta-4 (resistant), Valery (intermediate) and Agbagba (highly susceptible). Area under disease progress curve (AUDPC) was higher on all cultivars when inoculated with M. eumusae than with M. fijiensis, but significant (P<0·05) differences between the two species were only observed on Valery. Based on the rank-sum method, 8·3% of the isolates were classified as highly aggressive and 46·9% were classified as aggressive. About 11·5% of all the isolates were classified as least aggressive, and all of these were M. fijiensis. The majority of M. eumusae isolates (seven out of 11; 64%) were classified as aggressive. A total of nine pathotype clusters were identified using cluster analysis of AUDPC. At least one M. fijiensis isolate was present in all the nine pathotype clusters, while isolates of M. eumusae were present in six of the nine clusters. Isolates in pathotype clusters III and V were the most aggressive, while those in cluster VIII were the least aggressive. Shannon's index (H) revealed a more diverse Mycosphaerella collection in the DS zone (H=1·81) than in the HF (H=1·50) zone, with M. fijiensis being more diverse than M. eumusae. These results describe the current pathotype structure of Mycosphaerella in Nigeria and provide a useful resource that will facilitate screening of newly developed Musa genotypes for resistance against two important leaf spot diseases of banana and plantain. © 2012 The Authors. Plant Pathology © 2012 BSPP. Source

Brockhaus M.,CIFOR | Korhonen-Kurki K.,CIFOR | Korhonen-Kurki K.,University of Helsinki | Sehring J.,CIFOR | And 20 more authors.
Climate Policy

Reducing emissions from deforestation and forest degradation (REDD+) has emerged as a promising climate change mitigation mechanism in developing countries. This article examines the national political context in 13 REDD+ countries in order to identify the enabling conditions for achieving progress with the implementation of countries’ REDD+ policies and measures. The analysis builds on a qualitative comparative analysis of various countries’ progress with REDD+ conducted in 12 REDD+ countries in 2012, which highlighted the importance of factors such as already initiated policy change, and the presence of coalitions calling for broader policy change. A follow-up survey in 2014 was considered timely because the REDD+ policy arena, at the international and country levels, is highly dynamic and undergoes constant evolution, which affects progress with REDD+ policy-making and implementation. Furthermore, we will now examine whether the ‘promise’ of performance-based funds has played a role in enabling the establishment of REDD+. The results show a set of enabling conditions and characteristics of the policy process under which REDD+ policies can be established. The study finds that the existence of broader policy change, and availability of performance-based funding in combination with strong national ownership of the REDD+ policy process, may help guide other countries seeking to formulate REDD+ policies that are likely to deliver efficient, effective and equitable outcomes. Policy relevance Tropical forest countries struggle with the design and implementation of coherent policies and measures to reduce emissions from deforestation and forest degradation. Evidence on which factors and configurations are crucial to make progress towards these challenging policy objectives will be helpful for decision makers and practitioners at all levels involved in REDD+. Key findings highlight the importance of already initiated policy change, and the availability of performance-based funding in combination with strong national ownership of the REDD+ process. These findings provide guidance to REDD+ countries as to which enabling conditions need to be strengthened to facilitate effective, efficient and equitable REDD+ policy formulation and implementation. © 2016 Informa UK Limited, trading as Taylor & Francis Group Source

Vroh-Bi I.,International Institute Of Tropical Agriculture | Vroh-Bi I.,c o Lambourn Ltd | Anagbogu C.,University of Ibadan | Nnadi S.,International Institute Of Tropical Agriculture | And 2 more authors.
Plant Molecular Biology Reporter

Unexpected variations can occur during natural and in vitro propagation of bananas (banana and plantain) to generate off-types. The molecular basis of such variations is not well-understood. This study aimed to characterize the functions of genomic regions varying within clones grown naturally or in vitro. Fifty-four simple sequence repeat (SSR) markers and six primer combinations of EcoR I/Msp I-amplified fragment length polymorphism (AFLP) were used to analyze accessions of the AA, BB, AB, AAA, AAB, and ABB groups of Musa, and polymorphic regions were sequenced to characterize candidate genes. One SSR locus with significant similarity to an arcelin gene revealed a deletion in a subculture regenerant. In AFLP analysis, 24 (6.15%) of 390 bands accounted for within-clone variations, with 0.5% and 5.65% occurring in natural and in vitro propagated plants, respectively. Sequence homology searches revealed that most polymorphic regions were related to cytochrome P450, cell-wall biosynthesis, and senescence genes. The importance of these candidate genes is discussed. The plants harboring the variations were field-established to relate molecular variations to phenotypic changes. Sixteen of the sequences registered in Genbank (ET165586 to ET165601) and select PCR primers from this study can be further tested for variations between normal clones and off-types in Musa. © 2010 Springer-Verlag. Source

Pouomogne V.,Humid Forest Ecoregional Center | Brummett R.E.,Humid Forest Ecoregional Center | Gatchouko M.,Humid Forest Ecoregional Center
Journal of Applied Aquaculture

To measure the impact of past projects on the sustained adoption and development of aquaculture, and to assess the potential for future growth, a participatory rural appraisal (PRA) based on the Research Tool for Natural Resource Management, Monitoring and Evaluation (RESTORE) of 100 farmers (62 with fishponds, 38 without) was undertaken between January and August 2001 in the Noun Division of Western Province, Cameroon. The average household of 14 persons possessed 5.5 ha of land. Educational level is low (less then 35% above primary, 24% illiterate). Most fish producers were small-scale farmers (79%). Of the 360 fish farmers possessing 445 fish ponds (250 m2 average surface area), only 23% were active. Production is primarily based on earthen ponds stocked with mixed-sex tilapia (Oreochromis niloticus) grown alone (42%) or in polyculture (54%) with the African catfish (Clarias gariepinus). Most ponds are poorly managed, containing underfed fish despite the availability of large quantities of agricultural by-products that could be used as pond inputs. Average annual yield is 1,263 kg/ha. Despite a number of aquaculture development projects over 30 years, there were no significant differences (P < 0.05) in household economics and farming systems between fish farming and non-fish farming families. According to active fish farmers, the major constraints to increasing aquaculture production to make it economically interesting are: lack of technical assistance (46%) and lack of good fingerlings (30%). Recent political and economic changes have altered the outlook for aquaculture in Cameroon, and a development strategy based on new rural development policies is discussed. © Taylor & Francis Group, LLC. Source

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