Seed potato quality improvement through positive selection by smallholder farmers in Kenya

In Kenya, seed potato quality is often a major yield constraint in potato production as smallholder farmers use farm-saved seed without proper management of seed-borne pests and diseases. Farm-saved seed is therefore often highly degenerated. We carried out on-farm research to assess whether farmer-managed positive seed selection could improve yield. Positive selection gave an average yield increase in farmer-managed trials of 34%, corresponding to a 284-€ increase in profit per hectare at an additional production cost of only 6€/ha. Positive selection can be an important alternative and complementary technology to regular seed replacement, especially in the context of imperfect rural economies characterized by high risks of production and insecure markets. It does not require cash investments and is thus accessible for all potato producers. It can also be applied where access to highquality seed is not guaranteed. The technology is also suitable for landraces and not recognized cultivars that cannot be multiplied formally. Finally, the technology fits seamlessly within the seed systems of Sub-Saharan Africa, which are dominated by self-supply and neighbour supply of seed potatoes

DRAFT 03

DRAFT 03, a magazine published about work and thoughts of students and staff of Interiors

The HIV-1 transmission bottleneck

It is well established that most new systemic infections of HIV-1 can be traced back to one or a limited number of founder viruses. Usually, these founders are more closely related to minor HIV-1 populations in the blood of the presumed donor than to more abundant lineages. This has led to the widely accepted idea that transmission selects for viral characteristics that facilitate crossing the mucosal barrier of the recipient’s genital tract, although the specific selective forces or advantages are not completely defined. However, there are other steps along the way to becoming a founder virus at which selection may occur. These steps include the transition from the donor’s general circulation to the genital tract compartment, survival within the transmission fluid, and establishment of a nascent stable local infection in the recipient’s genital tract. Finally, there is the possibility that important narrowing events may also occur during establishment of systemic infection. This is suggested by the surprising observation that the number of founder viruses detected after transmission in intravenous drug users is also limited. Although some of these steps may be heavily selective, others may result mostly in a stochastic narrowing of the available founder pool. Collectively, they shape the initial infection in each recipient

A geo-coded inventory of anophelines in the Afro-Tropical region south of the Sahara: 1898-2016

Background: Understanding the distribution of anopheline vectors of malaria is an important prelude to the design of national malaria control and elimination programmes. A single, geo-coded continental inventory of anophelines using all available published and unpublished data has not been undertaken since the 1960s. Methods: We have searched African, European and World Health Organization archives to identify unpublished reports on anopheline surveys in 48 sub-Saharan Africa countries. This search was supplemented by identification of reports that formed part of post-graduate theses, conference abstracts, regional insecticide resistance databases and more traditional bibliographic searches of peer-reviewed literature. Finally, a check was made against two recent repositories of dominant malaria vector species locations (circa 2,500). Each report was used to extract information on the survey dates, village locations (geo-coded to provide a longitude and latitude), sampling methods, species identification methods and all anopheline species found present during the survey. Survey records were collapsed to a single site over time. Results: The search strategy took years and resulted in 13,331 unique, geo-coded survey locations of anopheline vector occurrence between 1898 and 2016. A total of 12,204 (92%) sites reported the presence of 10 dominant vector species/sibling species; 4,473 (37%) of these sites were sampled since 2005. 4,442 (33%) sites reported at least one of 13 possible secondary vector species; 1,107 (25%) of these sites were sampled since 2005. Distributions of dominant and secondary vectors conform to previous descriptions of the ecological ranges of these vectors. Conclusion: We have assembled the largest ever geo-coded database of anophelines in Africa, representing a legacy dataset for future updating and identification of knowledge gaps at national levels. The geo-coded database is available on Harvard Dataverse as a reference source for African national malaria control programmes planning their future control and elimination strategies

The prevalence of Plasmodium falciparum in sub-Saharan Africa since 1900

Malaria transmission is influenced by climate, land use and deliberate intervention. Recent declines have been observed in malaria transmission. Here, we show that the continent has witnessed a long-term recession in the prevalence of Plasmodium falciparum since 1900-29 (40%) to 2010-15 (24%), interrupted at different times by periods of rapidly increasing and decreasing transmission. The cycles and trend over the last 115 years are inconsistent with simplistic explanations in terms of climate or intervention alone. Previous global initiatives had minor impacts on malaria transmission, and a historically unprecedented decline has been observed since 2000. However, there has been little change to the continued high transmission belt covering large parts of West and Central Africa. Previous efforts to model the changing patterns of P. falciparum transmission intensity in Africa have been limited to the last 15 years1,2, or have used maps of historical expert opinion3. We provide quantitative data comprising 50,424 surveys at 36,966 geocoded locations to cover 115 years of malaria history in sub-Saharan Africa

The prevalence of Plasmodium falciparum in sub-Saharan Africa since 1900

Malaria transmission is influenced by climate, land use and deliberate intervention. Recent declines have been observed in malaria transmission. Here, we show that the continent has witnessed a long-term recession in the prevalence of Plasmodium falciparum since 1900-29 (40%) to 2010-15 (24%), interrupted at different times by periods of rapidly increasing and decreasing transmission. The cycles and trend over the last 115 years are inconsistent with simplistic explanations in terms of climate or intervention alone. Previous global initiatives had minor impacts on malaria transmission, and a historically unprecedented decline has been observed since 2000. However, there has been little change to the continued high transmission belt covering large parts of West and Central Africa. Previous efforts to model the changing patterns of P. falciparum transmission intensity in Africa have been limited to the last 15 years1,2, or have used maps of historical expert opinion3. We provide quantitative data comprising 50,424 surveys at 36,966 geocoded locations to cover 115 years of malaria history in sub-Saharan Africa

Positive selection in seed potato production in Kenya as a case of successful research-led innovation

By identifying the success factors of a programme on positive seed potato selection, this article analyses the role of research in agricultural innovation. The positive seed selection programme developed an approach to improve the quality of seed potatoes by ware potato growers, complementary to specialized seed production systems now widely promoted in sub-Saharan Africa. With more weight being placed on innovation rather than on research outcome, the role of research has been widened and research has assumed responsibility for developing and piloting effective training through partnership with extension. Researchers effectively contributed to innovation because they were given and took the liberty of pursuing a ‘bright idea’. The case discussed in this article points out that innovation can emerge from old technology within existing institutional environments, and can be surprisingly simple as long as researchers have room to manoeuvre and opportunity to engage in partnerships with practitioners