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Farmers' resource endowment and risk management affect agricultural practices and innovation capacity in the Northwestern uplands of Cambodia
No full textContext: The Northwestern uplands of Cambodia underwent a massive land conversion from forest to agriculture over the last 15 years. Objective: Our study conducted in Rotonak Mondol District, Battambang Province aimed at understanding farm diversity, trajectory, performance and capacity to innovate in order to identify effective interventions in a rapidly changing pioneer front. Methods: Based on a survey of 365 randomly selected households, we identified 4 main farm types by a combination of Principal Component Analysis and Cluster Analysis. The survey was complemented with detailed analyses of resource use, labor management, economic productivity and adoption of innovative practices on 95 households. Results and conclusions: The livelihood of Paddy Farms (20%) is centered on a rice-cattle combination with off-farm activities and annual upland crop farming providing cash income. The Large Farms (20%) specialize in intensive and mechanized upland crops, including orchards. The Small Farms (25%) have a diverse activity portfolio including paddy, annual upland crops, and off-farm activities. The livelihood of the Off-Farm type (35%) is largely based on low-income off-farm activities. We identified the time of arrival, initial cash and labor, relationship with local authorities, and/or social connections as key factors determining farm structures and livelihoods. This, in turn, determined farm capacities to accumulate resources during the maize boom that occurred in this region between 2006 and 2011. Based on our analysis of farm diversity, we identified interventions suitable to each farm type and opportunities for on-farm innovation through risk buffering mechanisms and strengthening of social organizations. Significance: Like in other pioneer fronts beyond our case study in Cambodia, a reorganization of the agricultural systems is required to support the shift from essentially individualistic behaviors to more concerted actions. The emergence of new institutions, such as farmer groups and cooperatives, can build upon the specific capacity and needs of the different types of farming systems to innovat
In-situ variability of DOM in relation with biogeochemical and physical parameters in December 2017 in Laucala Bay (Fiji Islands) after a strong rain event
No full textHeavy rain events alter the biogeochemical outflows, affects water quality and ecosystem health within the coastal waters of small Pacific Islands. We characterized snapshots of the optical fingerprints of dissolved organic matter (DOM) sources together with the select nutrients, biogeochemical and physical variables for 10 stations in December 2017 in Laucala Bay, Fiji Islands. DOM absorption coefficients and fluorescence components were determined via spectrofluorometry and Parallel Factor Analysis identifying four components: Type M, two terrestrial (humic, fulvic) components, and a protein component linked to marine biological activity. Associations of DOM together with climate variables and the other tested variables were determined via principal component, hierarchical cluster, and cross-correlation (Pearson) analysis. All components (together with most tested variables) displayed higher values (plumes) at the southwest coast consistent with surface currents outflow during the wet season. Type M component associated with two allochthonous fluorescent components signaling anthropogenic forcings via riverine outflows. Terrigenous inputs association with autochthonous chromophoric dissolved organic matter (CDOM) is indicative of tidal mixing, dilution, and bottom resuspension processes. Positive correlations of dissolved organic carbon (DOC) with nutrients (NOx, PO4) elucidates DOM being utilized as energy sources.The positive correlation of DON with nutrients (NOx, PO4, Si(OH)4) reflects the role of DON as a nutrient source consistent with chlorophyll plume formation
Improved decadal predictions of North Atlantic subpolar gyre SST in CMIP6
No full textDue to its wide-ranging impacts, predicting decadal variations of sea surface temperature (SST) in the subpolar North Atlantic remains a key goal of climate science. Here, we compare the representation of observed subpolar SST variations since 1960 in initialized and uninitialized historical simulations from the 5th and 6th phases of the Coupled Model Intercomparison Project (CMIP5/6). Initialized decadal hindcasts from CMIP6 explain 88% of observed SST variance post-1980 in the subpolar gyre at lead years 5-7 (77% in uninitialized simulations) compared to 42% (8%) in CMIP5, indicating a more prominent role for forcing in driving observed subpolar SST changes than previously thought. Analysis of single-forcing experiments suggests much of this correlation is due to natural forcing, explaining similar to 55% of the observed variance. The amplitude of observed subpolar SST variations is underestimated in historical simulations and improved by initialization in CMIP6, indicating continued value of initialization for predicting North Atlantic SST
Describing, analysing and understanding the effects of the introduction of HIV self-testing in West Africa through the ATLAS programme in Cote d'Ivoire, Mali and Senegal
No full textBackgroundThe ATLAS programme aims to promote and implement HIV self-testing (HIVST) in three West African countries: Cote d'Ivoire, Mali, and Senegal. During 2019-2021, in close collaboration with the national AIDS implementing partners and communities, ATLAS plans to distribute 500,000 HIVST kits through eight delivery channels, combining facility-based, community-based strategies, primary and secondary distribution of HIVST.Considering the characteristics of West African HIV epidemics, the targets of the ATLAS programme are hard-to-reach populations: key populations (female sex workers, men who have sex with men, and drug users), their clients or sexual partners, partners of people living with HIV and patients diagnosed with sexually transmitted infections and their partners.The ATLAS programme includes research support implementation to generate evidence for HIVST scale-up in West Africa.The main objective is to describe, analyse and understand the social, health, epidemiological effects and cost-effectiveness of HIVST introduction in Cote d'Ivoire, Mali and Senegal to improve the overall HIV testing strategy (accessibility, efficacy, ethics).MethodsATLAS research is organised into five multidisciplinary workpackages (WPs): qualitative surveys (individual in-depth interviews, focus group discussions) conducted with key actors, key populations, and HIVST users.Key Populations WP: ethnographic observation of three HIV care services introducing HIVST for partner testing.Index testing WP: an anonymous telephone survey of HIVST users.Coupons survey WP: incremental economic cost analysis of each delivery model using a top-down costing with programmatic data, complemented by a bottom-up costing of a representative sample of HIVST distribution sites, and a time-motion study for health professionals providing HIVST.Cost study WP: Adaptation, parameterisation and calibration of a dynamic compartmental model that considers the varied populations targeted by the ATLAS programme and the different testing modalities and strategies.DiscussionATLAS is the first comprehensive study on HIV self-testing in West Africa. The ATLAS programme focuses particularly on the secondary distribution of HIVST. This protocol was approved by three national ethic committees and the WHO's Ethical Research Committee
Rhizobia use a pathogenic-like effector to hijack leguminous nodulation signalling
No full textLegume plants form a root-nodule symbiosis with rhizobia. This symbiosis establishment generally relies on rhizobium-produced Nod factors (NFs) and their perception by leguminous receptors (NFRs) that trigger nodulation. However, certain rhizobia hijack leguminous nodulation signalling via their type III secretion system, which functions in pathogenic bacteria to deliver effector proteins into host cells. Here, we report that rhizobia use pathogenic-like effectors to hijack legume nodulation signalling. The rhizobial effector Bel2-5 resembles the XopD effector of the plant pathogen Xanthomonas campestris and could induce nitrogen-fixing nodules on soybean nfr mutant. The soybean root transcriptome revealed that Bel2-5 induces expression of cytokinin-related genes, which are important for nodule organogenesis and represses ethylene- and defense-related genes that are deleterious to nodulation. Remarkably, Bel2-5 introduction into a strain unable to nodulate soybean mutant affected in NF perception conferred nodulation ability. Our findings show that rhizobia employ and have customized pathogenic effectors to promote leguminous nodulation signalling
Multiscale Impacts of Anthropogenic and Climate Changes on Tropical and Mediterranean Hydrology [Editorial]
No full textQuantifying and characterizing hourly human exposure to malaria vectors bites to address residual malaria transmission during dry and rainy seasons in rural Southwest Burkina Faso
No full textBackgroundTo sustain the efficacy of malaria vector control, the World Health Organization (WHO) recommends the combination of effective tools. Before designing and implementing additional strategies in any setting, it is critical to monitor or predict when and where transmission occurs. However, to date, very few studies have quantified the behavioural interactions between humans and Anopheles vectors in Africa. Here, we characterized residual transmission in a rural area of Burkina Faso where long lasting insecticidal nets (LLIN) are widely used.MethodsWe analysed data on both human and malaria vectors behaviours from 27 villages to measure hourly human exposure to vector bites in dry and rainy seasons using a mathematical model. We estimated the protective efficacy of LLINs and characterised where (indoors vs. outdoors) and when both LLIN users and non-users were exposed to vector bites.ResultsThe percentage of the population who declared sleeping under a LLIN the previous night was very high regardless of the season, with an average LLIN use ranging from 92.43 to 99.89%. The use of LLIN provided >80% protection against exposure to vector bites. The proportion of exposure for LLIN users was 29-57% after 05:00 and 0.05-12% before 20:00. More than 80% of exposure occurred indoors for LLIN users and the estimate reached 90% for children under 5 years old in the dry cold season.ConclusionsLLINs are predicted to provide considerable protection against exposure to malaria vector bites in the rural area of Diebougou. Nevertheless, LLIN users are still exposed to vector bites which occurred mostly indoors in late morning. Therefore, complementary strategies targeting indoor biting vectors in combination with LLIN are expected to be the most efficient to control residual malaria transmission in this area
Telephone peer recruitment and interviewing during a respondent-driven sampling (RDS) survey : feasibility and field experience from the first phone-based RDS survey among men who have sex with men in Cote d'Ivoire
No full textBackground Many respondent-driven sampling (RDS) methodologies have been employed to investigate hard-to-reach populations; however, these methodologies present some limits. We describe a minimally investigated RDS methodology in which peer recruitment and interviewing are phone-based. The feasibility of the methodology, field experiences, validity of RDS assumptions and characteristics of the sample obtained are discussed. Methods We conducted a phone-based RDS survey among men who have sex with men (MSM) aged 18 or above and living in Cote d'Ivoire. Eight initial MSM across Cote d'Ivoire were selected. Participants were asked to call a hotline to be registered and interviewed by phone. After the participants completed the questionnaire, they were asked to recruit a maximum of 3 MSM from their acquaintances. Results During the 9 months of the survey, 576 individuals called the hotline, and 518 MSM completed the questionnaire. The median delay between the invitation to participate and the completion of the questionnaire by peer-recruited MSM was 4 days [IQR: 1-12]. The recruitment process was not constant, with high variation in the number of people who called the hotline during the survey period. RDS chain convergence to equilibrium was reached within 6 waves for most of the selected variables. For the network size estimation assumption, participants who incorrectly estimated their network size were observed. Regarding the sample obtained, MSM were recruited from all the regions of Cote d'Ivoire with frequent interregional recruitment; 23.5% of MSM were recruited by someone who does not live in the same region. Compared to the MSM who participated in two other surveys in Cote d'Ivoire, the MSM in our sample were less likely to know about an MSM non-governmental organisation. However, MSM aged 30 years old and above and those with a low level of education were underrepresented in our sample. Conclusion We show that phone-based RDS surveys among MSM are feasible in the context of sub-Saharan Africa. Compared to other classical RDS survey methodologies, the phone-based RDS methodology seems to reduce selection bias based on geography and proximity with the MSM community. However, similar to other methodologies, phone-based RDS fails to reach older and less-educated MSM
Detection of the elusive Dwarf sperm whale (Kogia sima) using environmental DNA at Malpelo island (Eastern Pacific, Colombia)
No full textMonitoring large marine mammals is challenging due to their low abundances in general, an ability to move over large distances and wide geographical range sizes. The distribution of the pygmy (Kogia breviceps) and dwarf (Kogia sima) sperm whales is informed by relatively rare sightings, which does not permit accurate estimates of their distribution ranges. Hence, their conservation status has long remained Data Deficient (DD) in the Red list of the International Union for Conservation of Nature (IUCN), which prevent appropriate conservation measures. Environmental DNA (eDNA) metabarcoding uses DNA traces left by organisms in their environments to detect the presence of targeted taxon, and is here proved to be useful to increase our knowledge on the distribution of rare but emblematic megafauna. Retrieving eDNA from filtered surface water provides the first detection of the Dwarf sperm whale (Kogia sima) around the remote Malpelo island (Colombia). Environmental DNA collected during oceanic missions can generate better knowledge on rare but emblematic animals even in regions that are generally well sampled for other taxa