Central Highlands Of Madagascar Research Articles

Population dynamics of plague vector fleas in an endemic focus: implications for plague surveillance.

Plague is a zoonotic vector-borne disease caused by the bacterium Yersinia pestis. In Madagascar, it persists in identified foci, where it is a threat to public health generally from September to April. A more complete understanding of how the disease persists could guide control strategies. Fleas are the main vector for transmission between small mammal hosts and humans, and fleas likely play a role in the maintenance of plague. This study characterized the dynamics of flea populations in plague foci alongside the occurrence of human cases. From 2018 to 2020, small mammals were trapped at sites in the central Highlands of Madagascar. A total of 2,762 small mammals were captured and 5,295 fleas were collected. The analysis examines 2 plague vector species in Madagascar (Synopsyllus fonquerniei and Xenopsylla cheopis). Generalized linear models were used to relate flea abundance to abiotic factors, with adjustments for trap location and flea species. We observed significant effects of abiotic factors on the abundance, intensity, and infestation rate by the outdoor-associated flea species, S. fonquerniei, but weak seasonality for the indoor-associated flea species, X. cheopis. A difference in the timing of peak abundance was observed between the 2 flea species during and outside the plague season. While the present study did not identify a clear link between flea population dynamics and plague maintenance, as only one collected X. cheopis was infected, the results presented herein can be used by local health authorities to improve monitoring and control strategies of plague vector fleas in Madagascar.

A machine learning approach is effective to elucidate yield-limiting factors of irrigated lowland rice under heterogeneous growing conditions and management practices

ContextIn the context of the heterogeneous field conditions for lowland rice production in sub-Saharan Africa, yield is adversely affected by a diverse array of complexly related factors, including environmental conditions, soil fertility, and fertilizer management, making it difficult to unravel the factors with greatest impact. In the central highlands of Madagascar, yield is constrained by low temperatures, insufficient rainfall, phosphorus deficiency, inadequate fertilizer input, and suboptimal agricultural practices. Identifying the driving factors by interpreting reliable predictive algorithms for the yield will greatly improve the optimization of rice productivity. ObjectiveIn this study, we aimed to apply machine learning to comprehensively elucidate the complex yield-limiting factors for lowland rice production across the central highlands of Madagascar. MethodsA machine learning algorithm was applied to comprehensively evaluate the factors affecting yield using a total of 578 data points, i.e., P-applied and non-P-applied plots in 289 farmers’ fields, consisting of their yield, weather, soil, and crop management across the central highlands of Madagascar. ResultsThere were large variations in yield ranging from 0.07 to 10.26 t ha−1. Machine learning explained the large yield variation well, especially in the Random Forest model, which showed the highest yield prediction accuracy. As relevant factors, high rice yields were associated with high growing degree days and high cumulative rainfall around 2 weeks before and after the heading date. Then, earlier transplanting in high elevation sites gave the optimum growing degree days, and the use of greater shoot-to-root ratio of seedlings during transplanting has the potential to enhance rice yields in the lowland rice system. ConclusionsMachine learning was significantly effective in identifying the individual effects of various factors controlling rice-yields under the heterogenous growing conditions of lowland-rice grown by smallholder farmers in the central highlands of Madagascar. ImplicationsFurther accumulation of crop management datasets will be needed in order to untangle the multifactorial components that reduce crop yields, even for small-scale farms.

Apple cultivation and its major challenging constraints in the Central Highlands of Madagascar

Apple cultivation and its major challenging constraints in the Central Highlands of Madagascar

Socioenvironmental determinants as indicators of plague risk in the central highlands of Madagascar: Experience of Ambositra and Tsiroanomandidy districts.

Human plague cases are reported annually in the central highland regions of Madagascar, where the disease is endemic. The socioenvironmental characteristics and lifestyles of the populations of the central highland localities could be linked to this endemicity. The aim of this study was to determine socioenvironmental determinants that may be associated with plague risk and explain this variation in epidemiological contexts. The current study was based on the distribution of plague cases between 2006 and 2015 that occurred in localities of districts positioned in the central highlands. Household surveys were performed from June to August 2017 using a questionnaire and direct observations on the socioenvironmental aspects of households in selected localities. Bivariate and multivariate analyses were performed to highlight the socioenvironmental parameters associated with plague risk in both districts. A total of 503 households were surveyed, of which 54.9% (276/503) were in Ambositra and 45.1% (227/503) were in Tsiroanomandidy. Multivariate analyses showed that thatched roofs [adjusted odds ratio (AOR): 2.63; 95% confidence interval (95% CI): 1.78-3.88] and ground floor houses [AOR: 2.11; 95% CI: 1.3-3.45-] were significantly associated with the vulnerability of a household to plague risk (p value<0.05). Plague risk in two districts of the Malagasy central highlands is associated with human socioenvironmental characteristics. Socioenvironmental characteristics are parameters expressing spatial heterogeneity through the difference in epidemiological expression of the plague in Ambositra and Tsiroanomandidy. These characteristics could be used as indicators of vulnerability to plague risk in plague-endemic areas.

Taxonomic Studies on Malagasy Dalbergia (Fabaceae). IV. A New Species from Central and Southern Madagascar and a Narrowed Circumscription for D. emirnensis

Dalbergia emirnensis Benth. was previously treated as comprising two entities, the typical variety from the Central Highlands of Madagascar and D. emirnensis var. decaryi Bosser &amp; R. Rabev. from the southern part of the country at lower altitudes. Additional collections and analyses demonstrate that, as currently delimited, these taxa exhibit considerable, discontinuous variability in morphology, habitat, and distribution, a finding supported by a recent phylogenomic study. We show that the material previously included in the typical variety of D. emirnensis represents two morphologically and geographically distinct entities, one that occurs only in the Central Highlands of Madagascar and includes the type specimen, and another that is morphologically and genetically more akin to D. emirnensis var. decaryi, found in the Southern Highlands of Madagascar. We describe the latter as a new species, D. nemoralis Rakoton., Phillipson &amp; Crameri, in which we include D. emirnensis var. decaryi, recognizing it as a distinct subspecies. We also show that D. campenonii Drake should be treated as a synonym of D. emirnensis. Each of the accepted taxa is provided with a full description, a comprehensive listing of specimens examined, details of its geographic distribution and habitat, and a provisional risk of extinction assessment using the IUCN Red List categories and criteria; a line drawing is also provided for D. nemoralis subsp. nemoralis.

Remaining forests on the Central Highlands of Madagascar-Endemic and endangered aquatic beetle fauna uncovered.

Madagascar is known for its high endemism and as many as 90% of this unique diversity are forest-dwellers. Unfortunately, the forest cover of Madagascar is decreasing at an alarming rate. This decrease can also affect aquatic insects, but our knowledge on aquatic insect diversity and distribution on Madagascar are limited. Although the eastern rainforests are considered the most diverse, the Central Highlands of Madagascar also harbors unique microendemic fauna but has been less studied. Here, we analyze the aquatic Adephaga beetle fauna of three remaining protected forests of the Central Highlands. Diversity, abundance, and uniqueness are compared between and within natural forests and surrounding grasslands. At least 15 undescribed species were found, highlighting the Central Highlands as an important area for endemism. The natural forests and the surrounding grasslands differed significantly in species assemblages. Interestingly, the three remaining forests differed in their assemblages with the geographically more distant Manjakatompo Ankaratra having the most unique fauna but also the highest altitude span. By contrast, the species composition was similar between the peripheral zones of each of the three remaining forests. The similarity of the fauna in the peripheral open habitats illustrates how some local forest endemics are replaced with widespread generalists in degraded habitats. Our study shows that the remaining forests of the Central Highlands of Madagascar are important refuges of unique fauna at high risk of extinction.

Prediction of the soil properties of Malagasy rice soils based on the soil color and magnetic susceptibility

ABSTRACT Accurate assessments of soil properties are required to improve fertilizer management practices for crop production. Conventional chemical analysis in the laboratory is costly and time-consuming. Soil color is related to different soil compositions, while soil magnetic susceptibility (MS) has been found to reflect the abundance of magnetic minerals relevant to soil properties. Improving proximal sensing techniques for the analysis of soil color and MS provides opportunities for affordable and rapid assessments of soil properties. The aim of this study was to evaluate the potential use of soil color parameters and MS values to predict soil properties using stepwise multiple linear regression (SMLR), random forest (RF), and nonlinear regression approaches in lowland and upland fields in the central highlands of Madagascar. The target properties included the contents of soil organic carbon (SOC), total nitrogen (TN), oxalate-extractable phosphorus and iron (Feox), and the soil texture. The model prediction accuracy was assessed using the coefficient of determination (R2), root-mean-square error (RMSE), and the ratio of performance to interquartile distance (RPIQ). The use of soil color parameters yielded an acceptable prediction accuracy of the Feox content (loge Feox) for all rice fields (R2 = 0.54, RMSE = 0.55, RPIQ = 1.70) using the RF algorithm, while the SMLR approach gave the most accurate prediction for upland fields with acceptable reliabilities for SOC, Feox, and clay and sand content prediction, with R2 ranging from 0.43 to 0.67 and RPIQ from 1.63 to 1.77. In lowland fields, TN content was predicted with acceptable accuracy (R2 = 0.34, RMSE = 0.49, RPIQ = 1.71) using SMLR with the color parameter. The combination of the soil color parameters with the MS value as predictor variables increased SOC prediction for lowland fields using the RF approach (R2 = 0.57, RMSE = 6.37, RPIQ = 1.96). Use of the soil color and MS parameters was revealed to be a promising way to simplify the assessment of soil properties in upland and lowland ecosystems by using RF and SMLR approaches. A combined use of the soil color and MS parameters improved the prediction accuracy for the SOC content.

Identification of factors associated with residual malaria transmission using school-based serological surveys in settings pursuing elimination

BackgroundTargeted research on residual malaria transmission is important to improve strategies in settings pursuing elimination, where transmission reductions prove challenging. This study aimed to detect and characterize spatial heterogeneity and factors associated with Plasmodium falciparum infections and exposure, P. falciparum apical membrane antigen 1 (PfAMA1) antibody (Ab) response, in the Central Highlands of Madagascar (CHL).MethodsFrom May to July 2014, a cross-sectional school-based survey was carried out in 182 fokontany (villages) within 7 health districts of the CHL. Rapid diagnostic tests (RDTs) and a bead-based immunoassay including PfAMA1 antigen biomarker were used to estimate malaria prevalence and seroprevalence, respectively. Local Moran’s I index was used to detect spatial “hotspots”. Remotely sensed environmental data—temperature, vegetation indices, land covers, and elevation—were used in multivariable mixed-effects logistic regression models to characterize factors associated with malaria infection and cumulative exposure.ResultsAmong 6,293 school-children ages 2–14 years surveyed, RDT prevalence was low at 0.8% (95% CI 0.6–1.1%), while PfAMA1 Ab seroprevalence was 7.0% (95% CI 6.4–7.7%). Hotspots of PfAMA1 Ab seroprevalence were observed in two districts (Ankazobe and Mandoto). Seroprevalence increased for children living > 5 km from a health centre (adjusted odds ratio (OR) = 1.6, 95% CI 1.2–2.2), and for those experiencing a fever episode in the previous 2 weeks (OR 1.7, 95% CI 1.2–2.4), but decreased at higher elevation (for each 100-m increase, OR = 0.7, 95% CI 0.6–0.8). A clear age pattern was observed whereby children 9–10 years old had an OR of 1.8 (95% CI 1.2–2.4), children 11–12 years an OR of 3.7 (95% CI 2.8–5.0), and children 13–14 years an OR of 5.7 (95% CI 4.0–8.0) for seropositivity, compared with younger children (2–8 years).ConclusionThe use of serology in this study provided a better understanding of malaria hotspots and associated factors, revealing a pattern of higher transmission linked to geographical barriers in health care access. The integration of antibody-assays into existing surveillance activities could improve exposure assessment, and may help to monitor the effectiveness of malaria control efforts and adapt elimination interventions.

Phenotyping of a rice (Oryza sativa L.) association panel identifies loci associated with tolerance to low soil fertility on smallholder farm conditions in Madagascar.

Rice (Oryza sativa L.) is a staple food of Madagascar, where per capita rice consumption is among the highest worldwide. Rice in Madagascar is mainly grown on smallholder farms on soils with low fertility and in the absence of external inputs such as mineral fertilizers. Consequently, rice productivity remains low and the gap between rice production and consumption is widening at the national level. This study evaluates genetic resources imported from the IRRI rice gene bank to identify potential donors and loci associated with low soil fertility tolerance (LFT) that could be utilized in improving rice yield under local cultivation conditions. Accessions were grown on-farm without fertilizer inputs in the central highlands of Madagascar. A Genome-wide association study (GWAS) identified quantitative trait loci (QTL) for total panicle weight per plant, straw weight, total plant biomass, heading date and plant height. We detected loci at locations of known major genes for heading date (hd1) and plant height (sd1), confirming the validity of GWAS procedures. Two QTLs for total panicle weight were detected on chromosomes 5 (qLFT5) and 11 (qLFT11) and superior panicle weight was conferred by minor alleles. Further phenotyping under P and N deficiency suggested qLFT11 to be related to preferential resource allocation to root growth under nutrient deficiency. A donor (IRIS 313-11949) carrying both minor advantageous alleles was identified and crossed to a local variety (X265) lacking these alleles to initiate variety development through a combination of marker-assisted selection with selection on-farm in the target environment rather than on-station as typically practiced.

Comparative analysis of the Copernicus, TanDEM-X, and UAV-SfM digital elevation models to estimate lavaka (gully) volumes and mobilization rates in the Lake Alaotra region (Madagascar)

Abstract. Over the past few decades, developments in remote sensing have resulted in an ever-growing availability of topographic information on a global scale. A recent development is TanDEM-X (TerraSAR-X add-on for digital elevation measurements), an interferometric synthetic aperture radar (SAR) mission of the Deutsche Zentrum für Luft- und Raumfahrt, providing near-global coverage and 12 m resolution digital elevation models (DEMs). Moreover, ongoing developments in uncrewed aerial vehicle (UAV) technology have enabled acquisitions of topographic information at a sub-meter resolution. Although UAV products are generally preferred for volume assessments of geomorphic features, their acquisition remains a time-consuming task and is spatially constrained. However, some applications in geomorphology, such as the estimation of regional or national erosion quantities of specific landforms, require data over large areas. TanDEM-X data can be applied at such scales, but this raises the question of how much accuracy is lost because of the lower spatial resolution. Here, we evaluated the performance of the 12 m TanDEM-X DEM to (i) estimate gully volume, (ii) establish an area–volume relationship, and (iii) determine mobilization rates through comparison with a higher-resolution (0.2 m) UAV structure-from-motion (SfM) DEM and a lower resolution (30 m) Copernicus DEM. We did this for six study areas in the Lake Alaotra region (central Madagascar), where lavaka (gullies) are omnipresent and surface area changes over the period 1949–2010s are available for 699 lavaka. Copernicus-derived lavaka volume estimates were systematically too low, indicating that the Copernicus DEM is too coarse to accurately estimate volumes of geomorphic features at the lavaka scale (100–105 m2). Lavaka volumes obtained from TanDEM-X were similar to UAV-SfM volumes for the largest features, whereas the volumes of smaller features were generally underestimated. To deal with this bias we introduce a breakpoint analysis to eliminate volume reconstructions that suffer from processing errors as evidenced by significant fractions of negative volumes. This elimination allowed the establishment of an area–volume relationship for the TanDEM-X data with fitted coefficients within the 95 % confidence interval of the UAV-SfM relationship. Our calibrated area–volume relationship enabled us to obtain large-scale lavaka mobilization rates ranging between 18 ± 3 and 311 ± 82 tha-1yr-1 for the six different study areas, with an average of 108 ± 26 tha-1yr-1 for the full dataset. These results indicate that current lavaka mobilization rates are 2 orders of magnitude higher than long-term erosion rates. With this study we demonstrate that the global TanDEM-X 12 m DEM can be used to accurately estimate volumes of gully-shaped features at the lavaka scale (100–105 m2), where the proposed breakpoint method can be applied without requiring the availability of a higher-resolution DEM. Furthermore, we use this information to make a first assessment of regional lavaka erosion rates in the central highlands of Madagascar.

The complete mitochondrial genome of rare and Critically Endangered Anilany helenae (Microhylidae) of Madagascar

Anilany helenae is a Critically Endangered frog native to the central highlands of Madagascar. Due to ongoing habitat loss of its known range, this species’ population is considered declining, while little is known about its ecology, behavior, and taxonomy. Within the context of developing tools that can aid the conservation of Madagascar’s amphibian fauna, and add to the continued understanding of their taxonomy, we assembled its complete mitochondrial genome (Genbank Accession number MZ751042). This contributes the first complete mitochondrial genome of a microhylid from Madagascar, despite there being over 100 species in the Cophylinae subfamily alone. Anilany helenae’s circular mitochondrial genome is 17,519 bp long, contains 37 genes, and exhibits differences in gene arrangement compared with other microhylids, including the placement of protein coding genes nad1 and nad2. A phylogeny of the 13 protein coding genes of the few Madagascan anuran mitogenomes available, along with species from Africa and East Asia, places A. helenae along with the New Guinean Mantophryne lateralis in a basal position with respect to the other microhylids in the tree.

High Rickettsial Diversity in Rodents and Their Ectoparasites From the Central Highlands of Madagascar.

Rickettsioses are among emerging infectious diseases around the world. In Madagascar, little information is available regarding Rickettsia (Rickettsiales: Rickettsiaceae) diversity and their potential impacts on public health. In fact, molecular screening of ectoparasites of mammals reported the presence of three species, Rickettsia africae, Rickettsia typhi, and Rickettsia felis. The present study aims to investigate the diversity of Rickettsia in small mammals and associated ectoparasites (fleas and ticks) using a molecular approach. In September and December 2016, fieldworks were undertaken in two districts of Madagascar to capture small mammals using standard traps (Tomahawk and Sherman traps) and collect associated ectoparasites. In total, 12 taxa of ectoparasites (5 flea and 7 tick species) were collected from 89 individuals of four species of terrestrial small mammals. Rickettsia spp. were molecularly identified in one specimen of Rattus rattus (Rodentia: Muridae), one specimen of Pulex irritans (Siphonaptera: Pulicidae) as well as four specimens of Ixodes cf. colasbelcouri (Ixodida: Ixodidae). This study showed the presence of three phylogenetically distinct taxa of Rickettsia in small mammals and their ectoparasites. The current study broadens our knowledge on the diversity of Rickettsia in the Central Highlands of Madagascar and highlights for the first time the presence of Ri. felis in R. rattus and in tick, I. cf. colasbelcouri in Madagascar. Additional studies are needed to have exhaustive information on Rickettsia in small mammals and their ectoparasites, to determine their pathogenicity as well as their potential effects on public health in order to update the national policy for the control of emerging infectious diseases in Madagascar.

Nature’s “Free Lunch”: The Contribution of Edible Insects to Food and Nutrition Security in the Central Highlands of Madagascar

Edible insects are a healthy, sustainable, and environmentally friendly protein alternative. Thanks to their quantitative and qualitative protein composition, they can contribute to food security, especially in Africa, where insects have been consumed for centuries. Most insects are still harvested in the wild and used for household consumption. So far, however, little attention has been paid to insects’ real contribution to food security in low-income countries. Entomophagy, the human consumption of insects, is widespread in many rural areas of Madagascar, a country, at the same time, severely affected by chronic malnutrition. This case study was carried out in a region where entomophagy based on wild harvesting is a common practice and malnutrition is pervasive. The data were obtained in 2020 from a survey among 216 households in the rural commune of Sandrandahy in the central highlands of Madagascar. Descriptive statistics, correlation, and regression analysis were used to show the relative importance of insects for the local diet and to test various hypotheses related to food security. Results show that insects contribute significantly to animal protein consumption, especially in the humid season, when other protein sources are scarce. They are a cheap protein source, as much esteemed as meat by the rural population. There are no significant differences in the quantities of insects consumed by poorer versus richer households, nor between rural and urban households. Insect consumption amounts are strongly related to the time spent on wild harvesting. The importance of edible insects for poor, food-insecure rural areas and how entomophagy can be promoted for better food and nutrition security are discussed.

Why socio-economic and attitudinal factors cannot predict entomophagy in rural areas of Madagascar

Entomophagy is commonly promoted as one solution to fight global food insecurity. Although many research articles have been published on the perception and acceptance of edible insects in Western nations, comparatively little attention has been paid to developing countries. To narrow down the existing research gap, this study investigates insect consumption behaviour in rural areas of Madagascar, a country that is severely affected by chronic malnutrition. The data was obtained from a household survey conducted in January 2020 in the rural commune of Sandrandahy in the central highlands of Madagascar. Using systematic cluster sampling with probability proportional to size, in 12 out of 38 villages, a sample of 216 households was randomly chosen. Multiple linear regressions were used to determine factors that explain differences in the quantities of insects consumed between local consumers. The amount of time households spent for insect harvesting, a variable which was not considered in any of the other studies reviewed, is the single most important factor explaining the amounts of insects consumed. In light of the results, we try to explain why socio-economic factors and most of the product-related attitudinal factors do not play a role in predicting insect consumption patterns in rural areas of Madagascar. More studies with larger samples in Madagascar and other sub-Saharan African countries are needed to validate the results. Future research should seek to make use of mixed-method approaches to provide more context-specific instruments. The promotion of insect rearing as a farming activity, as opposed to harvesting in the wild, is recommended to overcome seasonal availability gaps, exploit the tremendous potential of edible insects for food security, and strengthen the tradition of entomophagy.

Living in tiny fragments: a glimpse at the ecology of Goodman's mouse lemurs (Microcebus lehilahytsara) in the relic forest of Ankafobe, Central Highlands, Madagascar.

Habitat fragmentation is one of the major types of anthropogenic change, though fragmented landscapes predate human intervention. At present, the Central Highlands of Madagascar are covered by extensive grasslands interspersed with small discrete forest patches of unknown antiquity. Ankafobe, an actively protected site, comprises two such fragments of 12 and 30ha, respectively, known to harbor three lemur species and other endemic wildlife. At this location, we conducted a survey of resident Goodman's mouse lemurs, Microcebus lehilahytsara, to determine baseline behavioral and ecological conditions for this isolated population. By studying primates in forest fragments, investigators can characterize the effects of shrinking habitats and decreasing connectivity on species diversity and survival, thus providing a glimpse into the potential resilience of species in the face of anthropogenic disturbance. Investigating the behavioral ecology of Goodman's mouse lemurs across their geographic range could help us understand their metabolic and ecological flexibility and predict species long-term survival prospects. We conducted night transect walks, using capture techniques and telemetry, to track eight radio-collared individuals. Preliminary density estimates based on a limited number of sightings (n = 18) were 2.19ind/ha, and home range assessments ranged between 0.22 and 3.67ha. Mouse lemurs traveled an average of 425m nightly during the 5-h tracking periods and primarily fed on fruits of the mistletoe Bakerella clavata. The finding that Goodman's mouse lemurs apparently thrive in the seasonally cold and arid forest fragments in the Central Highlands indicates that they may be among the most tolerant and adaptable lemur species in Madagascar. These results point towards an exciting research program that focuses on ecological tolerance as a mechanism for long-term species survival.

Sequential micro-dose fertilization strategies for rice production: Improved fertilizer use efficiencies and yields on P-deficient lowlands in the tropical highlands

Localized micro-dose fertilization near the seed or root zone can maximize returns from minimal fertilizer inputs. In transplanted rice production systems, two opportunities exist for implementing localized micro-dose fertilization: Micro-dosing the nursery bed at sowing and dipping seedling roots at transplanting. Previous studies have focused on the individual effects of these management options, whereas none have identified how a combination of these techniques affect rice yields and fertilizer use efficiencies. Herein, we examined the effects of nursery bed micro-dosing combined with dipping seedling roots in an N-enriched solution (N-dipping) and P-enriched slurry (P-dipping) at transplanting. On-farm experiments were conducted at three sites with nutrient-poor soils in the central highlands of Madagascar. The results demonstrated that phosphorus is a key element for localized micro-dose fertilization, while single and sequential N applications could hinder initial growth and grain yields in severely and moderately P-deficient fields. Grain yields were significantly improved by nursery bed N and P micro-dosing (16 %–23 %) and by P-dipping at transplanting (33 %–46 %), except for nursery bed micro-dosing in a relatively high-yielding and less P-deficient site. The effect of these treatments were independent, and thus the yield additively increased by 55 %–67 % in the severely and moderately P-deficient sites. Moreover, the nursery bed micro-dosing and P-dipping additively shortened the number of days to heading by 17–21 days in these sites, which reduced the risk of cold-induced stress at the reproductive stage. We conclude that the combination of N and P nursery bed micro-dosing and P-dipping at transplanting can be recommended for improving yields while reducing the risk of climate-induced stress for lowland rice production under low-input and P-deficient soils.

Phosphorus application affects lowland rice yields by changing phenological development and cold stress degrees in the central highlands of Madagascar

• P-deficiency delayed heading of rice by 6–24 days in Madagascar highlands. • Delayed heading in P deficiency had a positive effect on yield under no cold stress. • Phenological delay increased risk of cold stress at reproductive to ripening stages. • P effect was greater when avoiding cold stress by shortening days to heading. • P deficiency management should take into account the effect of P on rice phenology. Despite a general perception that phosphorus (P) deficiency delays phenological development in annual crops, the impacts of interaction between this phenological delay and climatic conditions on crop productivity remain poorly understood. On-farm experiments were conducted in the central highlands of Madagascar, where P deficiency and late-season low temperature stress frequently restrict rice yields. Rice X265 was grown under four different fertilizer treatments with different combinations of N and P during early, intermediate, and late transplanting dates (ETP, ITP, and LTP, respectively). Plants subject to no fertilizer or single N treatments showed delayed heading by 6–24 days. This notable delay in the phenological development favored biomass accumulation and resulted in greater yield in ETP when low temperature stress was negligible. In contrast, delay in phenological development without P application increased cooling degree days and spikelet sterility in ITP. Consequently, the effect of a single N application had a positive effect only in ETP. The effect of P was much greater in ITP than in ETP because P application alleviated not only P deficiency but low temperature stress as well by shortening day to heading. In LTP plots, yield was severely suppressed to less than 1 t ha −1 , with sterility rate above 75 %, irrespective of fertilizer treatment. This study provides field evidence that phenological delay under P deficiency has dual effects on grain yield and that optimal N and P management practice differs with climatic growing conditions. Changes in phenological development due to plant nutrient status and its interaction with climate-induced stress needs further attention for improving fertilizer management practice.

Soil phosphorus retention can predict responses of phosphorus uptake and yield of rice plants to P fertilizer application in flooded weathered soils in the central highlands of Madagascar

Efficient phosphorus (P) fertilizer management is highly required for resource-limited farmers to achieve higher yields in typical P-deficient farmlands in sub-Saharan Africa. Although soil P retention has been conventionally used to estimate the possible responses to P fertilizer applied to soils, its applicability has not been clearly confirmed at the field level. In this study, the applicability of P retention to predict the response of rice plants to P application was investigated using pot experiments with soils collected from various locations (N = 62) and on-farm experiments at two nutrient-poor sites (N = 38) in the central highlands of Madagascar. Further, we explored a simple prediction method of P retention for multiple location assessment in local farmers’ fields using an alternative property of soils collected from rice fields in the same region (N = 213). P retention was negatively correlated with the increase in rice P uptake (ΔPuptake, r = − 0.550) in the pot experiment and with the increase in yield (ΔYield, r = − 0.697) in the on-farm field experiment as a response to P application. Path analysis revealed that oxalate-extractable aluminum (Alox) content was the most important factor of P retention across all the soils, indicating that rice plants grown on soils with higher Alox and P retention are less sensitive to P application. Given its high correlation with P retention (r = 0.642) and its simplicity in measurement, we proposed the use of moisture content of air-dried soils (ωair) as a parameter to predict soil P retention. It was further confirmed that ωair had a significant negative correlation with ΔPuptake based on the pot experiment across a wide range of soil statuses (r = − 0.518). However, ωair could not clearly explain ΔYield within a small range of soil properties in the field experiment. Overall, soil P retention can predict the responses of rice plants to P application in the typical P-deficient and low-yielding lowlands in the central highlands of Madagascar, and this simple evaluation technique using air-dried soil moisture content will be helpful for the assessment of multiple rice fields on a broad scale.

Influence of Sociospatial determinants on knowledge, attitudes and practices related to the plague in a population living in endemic areas in the central highlands, Madagascar

BackgroundPlague is endemic to the central highlands of Madagascar. Sporadic human cases or outbreaks can occur annually in these areas. In Madagascar, the associations between endemicity and the knowledge, attitudes and practices (KAP) of the population with regard to this disease remain poorly documented. The aim of this study was to assess KAP related to plague among the population living in the central highlands.MethodsA cross-sectional survey was conducted in the general population from June to August 2017. Based on the reported cases of plague between 2006 and 2015 in two central highland districts, a KAP questionnaire was administered in the population. Based on the proportion of correct answers provided by respondents, KAP scores were classified into three KAP categories: low (< Mean - SD), medium (Mean ± SD) and good (> Mean + SD). Multivariate analyses were performed to determine the associations between population KAP scores related to plague and sociodemographic and epidemiological factors. In addition, individual interviews and focus groups with health professionals were conducted to assess plague perception.ResultsA total of 597 individuals participated in the survey; 20% (n = 119) had a good KAP score, 62% (n = 370) a medium KAP score and 18% (n = 108) a low KAP score. Among the 119 respondents with good KAP scores, 80% (n = 95) resided in Ambositra district, and 20% (n = 24) resided in Tsiroanomandidy district. According to the health professionals in the two districts, populations in endemic areas are well aware of the plague. There were significant associations (p < 0.05) of not owning a mobile phone, having no contact with a former plague case, and living in Tsiroanomandidy district with a lower KAP score.ConclusionThe results of the study showed the need to adapt plague control interventions to the local context to allow a better allocation of human and financial resources. Doing so would minimize delays in patient management care and increase community resilience to plague epidemics.

Spatial phylogenomics of acrobat ants in Madagascar—Mountains function as cradles for recent diversity and endemism

AbstractAimA crucial step to protecting biodiversity is assessing species diversity and endemism. We delineate spatial patterns of diversity in Malagasy ants on a phylogenetic and taxonomic level to identify centers of diversity and endemism, and evaluate the ‘museum vs. cradle’ hypothesis with regard to ant endemism.LocationMadagascar.TaxonAnts, genus Crematogaster.MethodsWe estimated distribution models for 33 Crematogaster species and generated a phylogeny based on ultraconserved elements. We calculated species richness (SR), phylogenetic diversity (PD), weighted (WE), phylogenetic endemism (PE), randomized phylogenetic diversity (PD‐sig), and relative phylogenetic diversity (RPD) and endemism (RPE). Categorical analyses of neo‐ and paleo‐endemism (CANAPE) and the phylo‐jaccard index were used to delineate centers of neo‐ and paleo‐endemism. We correlated these measures with elevation metrics to investigate the role of mountains in generating ant endemism.ResultsWe found extensive phylogenetic clustering (significantly low PD‐sig) and short branches (low RPD) at higher elevations in central and south‐central to southern Madagascar. In contrast, phylogenetic overdispersion (significantly high PD‐sig) and long branches (high RPD) predominate at lower elevations in eastern humid and northern western dry forests. CANAPE and phylo‐jaccard estimated five centers of endemism, whereby neo‐ and mixed endemism were significantly correlated with higher elevations, and paleo‐endemism with lower elevations.Main conclusionsCenters of ant endemism are located in western dry and humid forests of northern Madagascar, eastern humid forests, and in the southern Central Highland region. Mountainous areas appear to be cradles of recent diversification for acrobat ants, whereas lower elevations may be regarded as centers of paleo‐endemism and thus museums for relict lineages. Species diversification among acrobat ants may have coincided with the arrival of a new biome in the central highlands of Madagascar.