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ISRA, Senegal

Van Melle C.,International Institute Of Tropical Agriculture | Arinloye D.,International Institute Of Tropical Agriculture | Coulibaly O.,International Institute Of Tropical Agriculture | Vayssieres J.F.,CIRAD Persyst | Hell K.,International Institute Of Tropical Agriculture
Acta Horticulturae | Year: 2013

Mango (Mangifera indica L., Anacardiaceae) is a popular fruit in Africa because of its high nutritional and economic value. However, smallholders in Benin, a West African country, are currently unable to take advantage of this potential because of various constraints along the value chain. A survey with 150 mango producers in three agro-ecological zones revealed that producers estimate losses for grafted mangoes are 46% and for local mangoes 68%. They perceive phyto-sanitary problems (mainly fruit fly infestations) as well as poor access to markets as the main causes. Mango production in Benin is concentrated in the Northern Guinean Savannah (NGS) zone, and mostly done on small scale (80% ≤3 ha) with no use of purchased inputs (extensive). Profitability is relatively low, varying from minus 60 to 80 USD/ha in NGS and slightly higher in the other zones. The distance of the orchard to the road (remoteness) shows a negative trend regarding the profit per kg mango produced, which demonstrates high transaction costs. In order to reduce mango losses and increase profitability, an integrated approach is needed, both addressing phyto-sanitary problems as well as poor market access. The development of alternative and innovative value chains can contribute to filling the resource gaps at producer level. © 2013 ISHS.

Naylor G.R.S.,CSIRO | Delhom C.D.,U.S. Department of Agriculture | Cui X.,U.S. Department of Agriculture | Gourlot J.-P.,CIRAD Persyst | Rodgers J.,U.S. Department of Agriculture
Textile Research Journal | Year: 2014

An earlier study confirmed the influence of cotton fiber length characteristics on the High Volume Instrument™ (HVI) strength measurement and devised a quantitative correction factor to compensate for the effect. The current paper investigated the validity of two important assumptions utilized in the previous study. Firstly, single fiber testing confirmed that the particular sample preparation method used to generate samples of different fiber length characteristics from a common cotton sliver did not introduce any inherent damage to the fibers (and so this could not be the explanation for the observed trend in measured fiber strength as a function of fiber length). Secondly, the positioning of the jaws relative to the beard in the HVI strength measurement was explored. This positioning was found to be quite variable for replicate measurements on the same cotton being a function of the size of each individual beard. The average positioning between the different samples was found to be similar and this validated the assumption and approach used previously for deriving the correction factor for that particular sample set. Characterizing the position of the jaws was extended using a wider range of cotton samples. The HVI positioning algorithm appears to not simply be a function of the size of the beard (i.e. the 'amount' parameter), but is also dependent on fiber length characteristics. It was also observed that the reported HVI elongation values displayed both a significant bias due to fiber length and also a dependence on the size of individual beards tested. © The Author(s) 2014.

Neto M.S.,University of Sao Paulo | Scopel E.,CIRAD - Agricultural Research for Development | Corbeels M.,CIRAD - Agricultural Research for Development | Cardoso A.N.,Embrapa Cerrados | And 5 more authors.
Soil and Tillage Research | Year: 2010

No-tillage mulch-based (NTM) cropping systems have been widely adopted by farmers in the Brazilian savanna region (Cerrado biome). We hypothesized that this new type of management should have a profound impact on soil organic carbon (SOC) at regional scale and consequently on climate change mitigation. The objective of this study was thus to quantify the SOC storage potential of NTM in the oxisols of the Cerrado using a synchronic approach that is based on a chronosequence of fields of different years under NTM. The study consisted of three phases: (1) a farm/cropping system survey to identify the main types of NTM systems to be chosen for the chronosequence; (2) a field survey to identify a homogeneous set of situations for the chronosequence and (3) the characterization of the chronosequence to assess the SOC storage potential.The main NTM system practiced by farmers is an annual succession of soybean (Glycine max) or maize (Zea mays) with another cereal crop. This cropping system covers 54% of the total cultivated area in the region. At the regional level, soil organic C concentrations from NTM fields were closely correlated with clay+silt content of the soil (r2=0.64). No significant correlation was observed (r2=0.07), however, between these two variables when we only considered the fields with a clay+silt content in the 500-700gkg-1 range. The final chronosequence of NTM fields was therefore based on a subsample of eight fields, within this textural range. The SOC stocks in the 0-30cm topsoil layer of these selected fields varied between 4.2 and 6.7kgCm-2 and increased on average (r2=0.97) with 0.19kgCm-2year-1. After 12 years of NTM management, SOC stocks were no longer significantly different from the stocks under natural Cerrado vegetation (p<0.05), whereas a 23-year-old conventionally tilled and cropped field showed SOC stocks that were about 30% below this level.Confirming our hypotheses, this study clearly illustrated the high potential of NTM systems in increasing SOC storage under tropical conditions, and how a synchronic approach may be used to assess efficiently such modification on farmers' fields, identifying and excluding non desirable sources of heterogeneity (management, soils and climate). © 2010 Elsevier B.V.

Introduction. Since its arrival in Senegal in 2004, Bactrocera invadens (Diptera Tephritidae) synonymized with Bactrocera dorsalis has caused much economic damage in mango crops. Effective and efficient control activities against B. invadens were necessary in order to continue mango production, and biological control measures were envisaged. In such conditions, the government of Senegal allowed the Asian parasitoid Fopius arisanus to be released in some orchards around Ziguinchor. Materials and methods. The dynamics of fruit fly species was studied with lure traps (methyl eugenol and terpinyl acetate with Dichlorvos). Mango fruit were sampled from the control orchard and orchards with released F. arisanus, to compare the differences in tephritid infestation. Results and discussion. The levels of B. invadens populations were 1.6-2.5 times higher in the control than in orchards where F. arisanus was released. The fruit were also 5-6 times more infested in the control orchard than in those that received F. arisanus. Between May and July 2012 the majority of the pupae (92%) collected from fruit samples developed into adult flies, while only 39% of the pupae transformed to adults between October and December after effective action of the parasitoids. In both orchard treatments, the level of native fruit fly populations was about the same. Wild fruit were infested mostly by Ceratitis cosyra, from which were reared native parasitoids such as Fopius caudatus, F. silvestrii, F. desideratus, Diachasmimorpha fullawayi, D. carinata, Psyttalia cosyrae, and P. concolor. In contrast with Mangifera indica, Citrus spp., Anacardium occidentale, Psidium guayava, Saba senegalensis, and Landolphia heudelotii were mainly infested by B. invadens which showed parasitism by F. arisanus. Pteromalidae and Eulophidae were also found from the pest fly pupae. Killer flies (Diptera: Muscidae) such as Coenosia attenuata Stein, C. atra Meigen and C. tigrina Fabricius emerged from the fruit samples. Conclusion. Sanitation against fruit flies in Casamance should take into account the conservation of natural enemies such as parasitoids and predators for an effective biological control of tephritids. © 2015 Cirad/EDP Sciences.

Vayssieres J.-F.,CIRAD - Agricultural Research for Development | Vayssieres J.-F.,Biol Control Unit Afr | Sinzogan A.,University Abomey Calavi | Adandonon A.,University of Benin | And 22 more authors.
Fruits | Year: 2014

Introduction: Losses in West African commercial mango orchards due to fruit fly infestations have exceeded 50% by the middle of the crop season since 2005, resulting in considerable income loss for the growers. Materials and methods: In 2009, weekly monitoring of adult fruit fly species of economic significance was carried out in eight West African countries at 12 sites across five agro-ecological zones: (i) Humid Forest, (ii) Guinean savanna, (iii) Southern Sudan, (iv) Northern Sudan, and (v) Sahelian. Trapping was performed using methyl eugenol and terpinyl acetate in 288 Tephri-traps, targeting Bactrocera invadens and Ceratitis cosyra. Results: The data showed that B. invadens was present throughout the year in the Forest zone, abundant for 7 months, with a peak in May at the end of the mango season, C. cosyra being totally absent. In the Guinean savanna zone, B. invadens was abundant for 6-7 months, with a peak at the beginning of June coinciding with the season, with a few C. cosyra. In the Southern Sudan zone, B. invadens was abundant for 6 months, with a peak in mid-June during the season, C. cosyra peaking in April. In the Northern Sudan zone, B. invadens was abundant for 5 months, with a peak at the end of June at the end of the season, C. cosyra peaking in May. In the Sahelian zone, B. invadens was abundant for 4 months, peaking in August during the season, C. cosyra peaking just before. These preliminary results showed that the exotic species, B. invadens, was present at high levels [mean peak of 378 flies per trap per day (FTD)] in all agro-ecological zones, while the native species, C. cosyra, preferred the drier zones of West Africa, with lower population levels (mean peak of 77 FTD). Conclusion: Detection trapping of male flies with parapheromones is a useful indicator of field population levels and could be used to deploy control measures (IPM package) in a timely manner when the Economic Injury Level is reached. Control strategies for these quarantine mango fruit fly species are discussed with respect to agro-ecological zones and the phenological stages of the mango tree. © 2014 Cirad/EDP Sciences.

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