African Research Center on Bananas and Plantains

Douala, Cameroon

African Research Center on Bananas and Plantains

Douala, Cameroon
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Garna H.,Institute Superieur Of Biotechnologie Of Sidi Thabet | Emaga T.H.,University of Liège | Emaga T.H.,African Research Center on Bananas and Plantains | Robert C.,University of Liège | Paquot M.,University of Liège
Food Hydrocolloids | Year: 2011

A new technique for the purification of pectins using protein (sodium caseinate) was developed and that could replace the process of ethanol which is currently used in industries. Commercial pectins were used as a model to verify the feasibility of the process and to define some important parameters. The results indicated that this purification technique is based primarily on the electrostatic interactions between these two polymers. The electrostatic interactions were strongly dependent on pH and salt concentration. The maximum pectin precipitation was obtained at pH 3.5. At this pH, the pectin acquires a negative charge while the protein is positively charged, promoting thus their attractions. Furthermore, the dissociation of the pectin-caseinates complex and the precipitation of caseinate at pH 4.6 were observed in the presence of salt. This method is very specific, suggesting that it could be used to purify some electrically charged polysaccharides. © 2010 Elsevier Ltd.

Happi Emaga T.,University of Liège | Happi Emaga T.,African Research Center on Bananas and Plantains | Garna H.,Institute Superieur Of Biotechnologie Of Sidi Thabet | Paquot M.,University of Liège | Deleu M.,University of Liège
Food Hydrocolloids | Year: 2012

The binding of sodium caseinate to pectin using Isothermal Titration Calorimetry (ITC) under different pH values (2, 3, 3.5), and comparison of two purification processes (sodium caseinate or ethanol), based on the physicochemical characteristics of purified pectin was evaluated. The results indicated that ITC titration confirmed the existence of interactions between caseinates and pectin at pH 3 and 3.5. The interaction depicts two interdependent steps, one attributed to an electrostatic interaction and another related to a co-acervation mechanism. The chemical characteristics of pectins are strongly dependent on the purification process. Under some extraction conditions, ethanol is not specific to the recovery of pectin since it causes the precipitation of other compounds together with this polysaccharide.However, compared to the caseinate, it allows total precipitation of pectins extracted, but caseinates have the advantage of being more specific for the charged polymers. © 2012 Elsevier Ltd.

Dassou A.G.,CIRAD - Agricultural Research for Development | Dassou A.G.,African Research Center on Bananas and Plantains | Dassou A.G.,University of Benin | Tixier P.,CIRAD - Agricultural Research for Development | Tixier P.,Tropical Agriculture Research and Higher Education Center
Ecology and Evolution | Year: 2016

Disentangling the effects of plant diversity on the control of herbivores is important for understanding agricultural sustainability. Recent studies have investigated the relationships between plant diversity and arthropod communities at the landscape scale, but few have done so at the local scale. We conducted a meta-analysis of 32 papers containing 175 independent measures of the relationship between plant diversity and arthropod communities. We found that generalist predators had a strong positive response to plant diversity, that is, their abundance increased as plant diversity increased. Herbivores, in contrast, had an overall weak and negative response to plant diversity. However, specialist and generalist herbivores differed in their response to plant diversity, that is, the response was negative for specialists and not significant for generalists. While the effects of scale remain unclear, the response to plant diversity tended to increase for specialist herbivores, but decrease for generalist herbivores as the scale increased. There was no clear effect of scale on the response of generalist predators to plant diversity. Our results suggest that the response of herbivores to plant diversity at the local scale is a balance between habitat and trophic effects that vary according to arthropod specialization and habitat type. Synthesis and applications. Positive effects of plant diversity on generalist predators confirm that, at the local scale, plant diversification of agroecosystems is a credible and promising option for increasing pest regulation. Results from our meta-analysis suggest that natural control in plant-diversified systems is more likely to occur for specialist than for generalist herbivores. In terms of pest management, our results indicate that small-scale plant diversification (via the planting of cover crops or intercrops and reduced weed management) is likely to increase the control of specialist herbivores by generalist predators. © 2016 Published by John Wiley & Sons Ltd.

Duyck P.-F.,CIRAD | Dortel E.,CIRAD | Tixier P.,CIRAD | Vinatier F.,CIRAD | And 3 more authors.
Soil Biology and Biochemistry | Year: 2012

Understanding how environmental factors structure communities is important in conservation biology and ecosystem management. The aim of this study was to test the hypothesis that a plant-feeding nematode community composed of six species is structured by soil type and climate at the landscape scale, and that niche partitioning via these factors is consistent with the coexistence of the species. Martinique has an impressive diversity of abiotic factors (climate and soil type) over a relatively small land area, which facilitates the study of how soil type and climate affect the nematode community.We conducted this study by building an extensive data set containing the abundance of each nematode species on banana (3708 samples and 5,673,705 nematodes) in a wide range of sites in Martinique. The data set also contained environmental data (soil, climate) and plantation age. We analyzed the response of each nematode species to climate and soil type with a generalized linear model in order to understand whether niche partitioning of factors could contribute to the coexistence of the nematode species.Temperature, rainfall, soil type, and plantation age significantly affected the abundance of the six nematode species. While some pairs of species shared the same environmental niches, other showed clear niche partitioning along climatic axes. The two dominant species, Radopholus similis and Helicotylenchus multicinctus, have similar convergent ecological niches regarding climate, soil type, plantation age, and host range. These two species, which often co-occur, probably have different resources at the root scale. Soil type and climate structure plant-feeding nematode species community at the island scale. Further studies need to evaluate coexistence at the root scale among dominant species. © 2011 Elsevier Ltd.

Emaga T.H.,University of Liège | Emaga T.H.,African Research Center on Bananas and Plantains | Bindelle J.,University of Liège | Agneesens R.,Walloon Agricultural Research Center | And 3 more authors.
Tropical Animal Health and Production | Year: 2011

Musa sp. peels are widely used by smallholders as complementary feeds for cattle in the tropics. A study of the influence of the variety and the maturation stage of the fruit on fermentability and metabolisable energy (ME) content of the peels was performed using banana (Yangambi Km5) and plantain (Big Ebanga) peels at three stages of maturation in an in vitro model of the rumen. Peel samples were analysed for starch, free sugars and fibre composition. Samples were incubated in the presence of rumen fluid. Kinetics of gas production were modelled, ME content was calculated using prediction equation and short-chain fatty acids production and molar ratio were measured after 72 h of fermentation. Final gas production was higher in plantain (269-339 ml g-1) compared to banana (237-328 ml g-1) and plantain exhibited higher ME contents (8.9-9.7 MJ/kg of dry matter, DM) compared to banana (7.7-8.8 MJ/kg of DM). Butyrate molar ratio decreased with maturity of the peels. The main influence of the variety and the stage of maturation on all fermentation parameters as well as ME contents of the peels was correlated to changes in the carbohydrate fraction of the peels, including starch and fibre. © 2010 Springer Science+Business Media B.V.

Ewane C.A.,University of Liège | Ewane C.A.,African Research Center on Bananas and Plantains | Ewane C.A.,University of Yaounde I | Lepoivre P.,University of Liège | And 2 more authors.
Biotechnology, Agronomy and Society and Environment | Year: 2012

Crown rot of bananas, caused by a fungal parasitic complex, is one of the main quality defects of exported bananas. Major variations in the susceptibility of bananas to crown rot have been observed in different production zones. The physiological state of the banana fruit at harvest is said to influence its response to pathogenic attack and thus to modulate its susceptibility to crown rot. The susceptibility of bananas to this disease, however, appears to be influenced by many pre-harvest factors, although the underlying defense mechanisms have not been clearly identified. A recent report based on molecular analyses suggests that phenolic compounds might be involved in the different variations in the susceptibility of bananas to crown rot. Results of other earlier studies point to an involvement of phenolic compounds in the defensive reactions of banana plants against various pathogens. The present paper reviews the current state of knowledge on the variations in the susceptibility of bananas to crown rot and takes stock of what is known about phenolic compounds in relation to their potential involvement in the defense mechanisms of the banana plant.

Ewane C.A.,University of Liège | Ewane C.A.,African Research Center on Bananas and Plantains | Ewane C.A.,University of Yaounde I | Lassois L.,University of Liège | And 4 more authors.
Canadian Journal of Plant Pathology | Year: 2013

Crown rot of banana fruits is caused by a complex of fungal pathogens, the most common of which is Colletotrichum musae, and is one of the main quality defects of exported bananas. Susceptibility of banana fruits to crown rot is influenced by many pre-harvest factors. The aim of this study was to improve on the methodology for the evaluation of fruit susceptibility and to verify whether cultivation areas in Cameroon as well as seasonal variations have an influence on the susceptibility to crown rot. Fruit susceptibility was evaluated on a monthly basis throughout a year (including the dry and rainy seasons) in three banana plantations located in very different agro-ecological conditions (two in a lowland area and one in a highland area). Fruit susceptibility was determined through an internal necrotic surface (INS) assessment after artificial inoculation with C. musae. The standardization of post-inoculation environmental conditions enabled more reliable INS assessments. Fruit susceptibility was found to be significantly influenced by cultivation area (P < 0.001) since fruits grown in low altitude (Dia-dia, Koumba, 80 m) were more susceptible than fruits grown in high altitude (Ekona, 500 m). Although no seasonal effect was observed (P = 0.075), there was a highly significant date effect (P < 0.001). This was specifically the case in low-altitude plantations where fruit susceptibility was higher for some harvest dates within the rainy season. In Ekona, fruit grade and number of leaves on the banana plant were found to be significantly higher than in the two other locations, while black leaf streak disease severity was significantly lower. The potential relationship with fruit susceptibility is fully discussed. © 2013 The Canadian Phytopathological Society.

Emaga T.H.,University of Liège | Emaga T.H.,African Research Center on Bananas and Plantains | Rabetafka N.,University of Liège | Blecker C.S.,University of Liège | Paquot M.,University of Liège
Biotechnology, Agronomy and Society and Environment | Year: 2012

Different hydrolysis procedures of flaxseed polysaccharides (chemical and enzymatic) were carried out with H 2SO 4, HCl andTFA at different acid concentrations (0.2,1 and 2 M) and temperatures (80 and 100°C). Enzymatic and combined chemical and enzymatic hydrolyses of polysaccharide from flaxseed mucilage were also studied. Acid hydrolysis conditions (2 M H 2S 4, 4 h, 100°C) are required to quantify total monosaccharide content of flaxseed mucilage. The enzymatic pathway (Pectinex™ Ultra SP) limits sugar destruction during hydrolysis, but it is also insufficient for complete depolymerization. The combination of the two treatments, i.e. moderate chemical hydrolysis (0.2 M H 2SO 4, 80°C, 48 h) combined with enzymatic hydrolysis is not more effective compared to chemical hydrolysis in drastic conditions (2 M H 2SO 4 at 100°C). The strong interaction between the neutral and acid fractions of flaxseed mucilage may hinder total release of sugar residues. Physical treatment prior to the hydrolysis could be necessary to achieve complete depolymerisation of flaxseed mucilage.

PubMed | CIRAD - Agricultural Research for Development and African Research Center on Bananas and Plantains
Type: | Journal: Data in brief | Year: 2016

The data presented in this article are related to the research article entitled Ant abundance and Cosmopolites sordidus damage in plantain fields as affected by intercropping (A.G. Dassou, D. Carval, S. Dpigny, G.H Fansi, P. Tixier, 2015) [1]. This article describes how associated crops maize (Zea mays), cocoyam (Xanthosoma sagittifolium) and bottle gourd (Lagenaria siceraria) intercropped in the plantain fields in Cameroun modify ant community structure and damages of banana weevil Cosmopolites sordidus. The field data set is made publicly available to enable critical or extended analyzes.

Duyck P.-F.,CIRAD | Lavigne A.,CIRAD | Vinatier F.,CIRAD | Achard R.,CIRAD | And 2 more authors.
Basic and Applied Ecology | Year: 2011

Generalist predators can play an important role in agroecosystems by controlling herbivores via top-down effects. As cover crops are increasingly used in agroecosystems, the effects of this resource on generalist predator diet need to be evaluated. We studied the effect of adding a cover crop, Brachiaria decumbens, on trophic niches of generalist predators in a banana agroecosystem by analysing stable isotope variation in C and N for Cosmopolites sordidus, a major banana pest, and its potential predators (spiders, ants, centipedes, and earwigs). While addition of the new resource did not change the trophic niche of the banana pest C. sordidus, the trophic position of the generalist predators was changed as indicated by δ13C signature. Cover crop provided resources that are likely to support a community of insect herbivores, which are alternative preys for generalist predators. The failure of the cover crop to increase δ15N signature is inconsistent with the hypothesis that the cover crop would increase intraguild predation. By providing alternative preys, the addition of a new resource in agroecosystems has the potential to increase populations of generalist predators and therefore pest control.

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