Potential returns to yam research investment in sub-Saharan Africa and beyond.

Lack of good-quality planting materials has been identified as the most severe problem militating against increased agricultural productivity in sub-Saharan Africa (SSA) and beyond. However, investment of research efforts and resources in addressing this menace will only be feasible and worthwhile if attendant economic gains are considerable. As a way of investigating the economic viability of yam investment, this research has been initiated to address problems confronting yam productivity in eight countries of SSA and beyond: Nigeria, Ghana, Benin, Togo, Côte d'Ivoire, Papua New Guinea, Jamaica, and Columbia. Research options developed were to be deployed and disseminated. Key technologies include the adaptive yam minisett technique (AYMT), varieties adapted to low soil fertility and drought, nematode-resistant cultivars (NRC), and crop management and postharvest practices (CMPP). This article aims at estimating the potential economic returns, the expected number of beneficiaries, and poverty reduction consequent to the adoption of technology options. Estimates show that the new land area that will be covered by the technologies in the eight countries will range between 770,000 ha and 1,000,000 ha with the highest quota accounted for by AYMT. The net present value will range between US$584 and US$1392 million and was highest for the NRC. The CMPP had the lowest benefit-cost ratio of 7.74. About 1,049,000 people would be moved out of poverty by these technologies by 2037 in the region. These technologies are less responsive to changes in cost than that in adoption rate. Therefore, the realization of the potential economic gains depends on the rate and extent of adoption of these technologies. Giving the knowledge-intensive nature of some of these interventions, capacity building of potential adopters will be critical to increasing the sustainability of the yam sector, thereby enhancing food security and reducing poverty.

Genome of the African cassava whitefly Bemisia tabaci and distribution and genetic diversity of cassava-colonizing whiteflies in Africa.

The whitefy Bemisia tabaci, a species complex consisting of many morphologically indistinguishable species divided into distinct clades, is one of the most globally important agricultural pests and plant virus vectors. Cassava-colonizing B. tabaci transmits viruses that cause cassava mosaic disease (CMD) and cassava brown streak disease (CBSD). Half of all cassava plants in Africa are affected by these viral diseases, resulting in annual production losses of more than US$ 1 billion. Here we report the draft genome of the cassava whitefly B. tabaci Sub-Saharan Africa - East and Central Africa (SSA-ECA), the super-abundant population that has been associated with the rapid spread of viruses causing the pandemics of CMD and CBSD. The SSA-ECA genome assembled from Illumina short reads has a total size of 513.7 Mb and a scaffold N50 length of 497 kb, and contains 15,084 predicted protein-coding genes. Phylogenetic analysis suggests that SSA-ECA diverged from MEAM1 around 5.26 million years ago. A comprehensive genetic analysis of cassava-colonizing B. tabaci in Africa was also conducted, in which a total of 243 whitefly specimens were collected from 18 countries representing all major cassava-growing regions in the continent and genotyped using NextRAD sequencing. Population genomic analyses confirmed the existence of six major populations linked by gene flow and inferred the distribution patterns of these populations across the African continent. The genome of SSA-ECA and the genetic findings provide valuable resources and guidance to facilitate whitefly research and the development of strategies to control cassava viral diseases spread by whiteflies.