Musa germplasm diversity status across a wide range of agro-ecological zones in Rwanda

Objectives: This study assessed the on-farm Musa germplasm diversity across different agro-ecologies of Rwanda and the socio-economic utilization options and selection practices that create/maintain this diversity on-farm.Methodology and results: A Musa germplasm diagnostic survey was carried out in 2007 in five Rwandan districts on a transect from Lake Kivu (West) to Kirehe district (East) bordering Tanzania. Across all sites, 118 farms, each having at least 50 mats were sampled for determining Musa diversity. Forty three Musa cultivars were recorded across the five districts. Higher diversity was observed in the east declining westwards to the Lake Kivu region as reflected by the number of cultivars and their relative abundance. Nearly half of the recorded cultivars had a low diversity index (Gini-Simpson 1-D < 0.2) and therefore prone to genetic erosion. Cooking cultivars only dominate in the district of Kirehe, while beer cultivars dominate the banana production landscape in the other districts. Taste/flavor, bunch size and market demand were the most important criteria for banana cultivar selection and thus greatly influenced cultivar conservation and distribution on-farm. Diseases such as Fusarium wilt and Xanthomonas wilt greatly contributed to genetic erosion.Conclusion and application of results: Musa cultivar diversity in Rwanda is under threat. Ex-situ conservation of the menaced cultivars is of crucial importance. Beer cultivars dominated the landscape. Cultivar diversity on-farm was influenced by the prevailing altitude; taste/flavor, bunch size, and market demand of the cultivars; and their susceptibility to diseases especially Fusarium and Xanthomonas wilt. Banana breeding or adaptation strategies therefore should take into account the farmer preferred traits. In addition, strategies for managing these diseases are critical for preventing the genetic erosion of the affected cultivars.Keywords: cultivar evenness, cultivar richness, diversity index, genetic erosio

Genetic Diversity and Protective Efficacy of the RTS,S/AS01 Malaria Vaccine.

BACKGROUND: The RTS,S/AS01 vaccine targets the circumsporozoite protein of Plasmodium falciparum and has partial protective efficacy against clinical and severe malaria disease in infants and children. We investigated whether the vaccine efficacy was specific to certain parasite genotypes at the circumsporozoite protein locus. METHODS: We used polymerase chain reaction-based next-generation sequencing of DNA extracted from samples from 4985 participants to survey circumsporozoite protein polymorphisms. We evaluated the effect that polymorphic positions and haplotypic regions within the circumsporozoite protein had on vaccine efficacy against first episodes of clinical malaria within 1 year after vaccination. RESULTS: In the per-protocol group of 4577 RTS,S/AS01-vaccinated participants and 2335 control-vaccinated participants who were 5 to 17 months of age, the 1-year cumulative vaccine efficacy was 50.3% (95% confidence interval [CI], 34.6 to 62.3) against clinical malaria in which parasites matched the vaccine in the entire circumsporozoite protein C-terminal (139 infections), as compared with 33.4% (95% CI, 29.3 to 37.2) against mismatched malaria (1951 infections) (P=0.04 for differential vaccine efficacy). The vaccine efficacy based on the hazard ratio was 62.7% (95% CI, 51.6 to 71.3) against matched infections versus 54.2% (95% CI, 49.9 to 58.1) against mismatched infections (P=0.06). In the group of infants 6 to 12 weeks of age, there was no evidence of differential allele-specific vaccine efficacy. CONCLUSIONS: These results suggest that among children 5 to 17 months of age, the RTS,S vaccine has greater activity against malaria parasites with the matched circumsporozoite protein allele than against mismatched malaria. The overall vaccine efficacy in this age category will depend on the proportion of matched alleles in the local parasite population; in this trial, less than 10% of parasites had matched alleles. (Funded by the National Institutes of Health and others.)

Kairomone trapping system for delivery of Beauveria bassiana to control the banana weevil

No Abstract

Assessment of banana planting practices and cultivar tolerance in relation to management of soilborne Xanthomonas campestris pv musacearum

Experiments were carried out to evaluate various options to reduce wilting of bananas replanted to rehabilitate farms previously destroyed by Xanthomonas campestris pv musacearum (Xcm). Paring, time taken to cure paring injuries and covering corms with infested or uninfested soil were evaluated. Nine banana cultivars were evaluated for tolerance to infection by Xcm through roots. An average of 75% of corms planted immediately after paring and covered with infested topsoil wilted as compared to 25% incidence when pared corms were covered in uninfested soil and over-layered with infested soil. No plants wilted when pared corms were cured for 3 days before planting. Unpared corms planted and covered with infested soil on the same day they were dislodged from mother plants had an average of 40% wilt incidence. Unpared corms had less wilt incidence if kept for 2–3 days before planting. Differences were observed in cultivar susceptibility to infection through corms and roots with cultivars Enzagata and Yangabi Km5 being least susceptible. Cultivars Gonja, Kibuzi and Pisang Awak were more susceptible with 50–75% wilt incidence in pot trials and 36–45% in field trials. The less susceptible cultivars had fewer and shorter primary roots, and took an average of 69–77 days to wilt while the more susceptible cultivars had more and longer primary roots and wilted within 40–50 days after planting. Results of the study show that adjustments in planting practices could contribute to reducing wilting incidence and hence support efforts to rehabilitate banana productivity in farms devastated by Xcm.Peer Revie

Urban consumer willingness to pay for introduced dessert bananas in Uganda

Dessert bananas ( Musa spp.) form one of the world's most important fruits, yet one of the least traded commodities in Uganda. A range of exotic and hybrid dessert bananas that included KABANA 3H and KABANA 4H were introduced in Uganda in response to Fusarium wilt disease that was wiping away Gros Michel. However, the effect of dessert attributes and consumer characteristics on consumers' willingness to pay for these new bananas among the urban consumers was not known. This study was undertaken to determine awareness of the introduced dessert bananas among urban consumers, and the effect of introduced dessert banana attributes and consumer characteristics on willingness to pay for the introduced desert bananas. Results indicated that urban consumers had low awareness on the introduced dessert banana varieties. Similarly the introduced dessert bananas were acceptable to consumers though rated inferior to Gros Michel. All the sensory attributes of KABANA 3H and KABANA 4H were acceptable to urban consumers. Results from the hedonic pricing Models further suggested that taste, skin colour and texture had significant effect on the consumer willingness to pay for new dessert banana varieties. It is concluded that, the three introduced dessert bananas are acceptable and therefore have a market potential. It is recommended that market development activities including organising and training farmers in improved agronomic methods, handling bananas for local markets; and promotional studies of the introduced dessert bananas among the urban consumers be done to widen their demand.Les bananes dessert ( Musa spp.) représentent les fruits les plus importants de l'univers, et pourtant l'un des marchandises les moins négociés en Ouganda. Une gamme de bananes dessert exotiques et hybride qui incluait KABANA 3 H et KABANA 4 H avaient été introduits en Ouganda en réponse à la maladie de flétrissement par Fusarium qui avait éliminé Gros Michel. Toutefois, l'effet des attributs de la banane dessert et les caractéristiques de la préférence à acheter ces bananes parmi les consommateurs urbains n'était pas connu. Cette étude avait été entreprise afin de déterminer la connaissance du consommateur sur les bananes dessert introduites chez les consommateurs urbains et l'effet des attributs des bananes dessert introduites ainsi que les caractéristiques du consommateur par rapport à la préférence d'acheter les bananes désert introduites. Les résultats indiquaient que les consommateurs urbains avaient une moindre information sur les variétés de banane dessert introduites. De même, les bananes dessert introduites étaient acceptables par les consommateurs bien qu'à un taux nominal faible pour Gros Michel. Tout les attributs sensorielles de KABANA 3 H et KABANA 4 H étaient acceptables pour les consommateurs urbains. En plus Les résultats des Modèles de tarification hedonic suggèrent que la saveur, couleur de peau et la texture avaient un effet significatif sur la motivation du consommateur à acheter de nouvelles variétés de banane dessert. Il est conclu que les trois variété de bananes dessert introduites avaient un marché potentiel important. Il est recommandé que les activités de développement du marché, y compris l'organisation et la formation des agriculteurs sur l'amélioration des pratiques agronomiques, gestion des bananes pour les marchés locaux; ainsi que les études promotionnelles sur la banane dessert introduite chez les consommateurs urbains se fasse afin d'accroître leur demande

Use of hebicides for control of banana bacterial wilt in Uganda

No Abstract. African Crop Science Jouranl Vol. 14 (2) 2006: pp. 143-15