Agent-Based Modeling of Human-Induced Spread of Invasive Species in Agricultural Landscapes: Insights from the Potato Moth in Ecuador

Agent-based models (ABM) are ideal tools to deal with the complexity of pest invasion throughout agricultural socio-ecological systems, yet very few studies have applied them in such context. In this work we developed an ABM that simulates interactions between farmers and an invasive insect pest in an agricultural landscape of the tropical Andes. Our specific aims were to use the model 1) to assess the importance of farmers\' mobility and pest control knowledge on pest expansion and 2) to use it as an educational tool to train farmer communities facing pest risks. Our model combined an ecological sub-model, simulating pest population dynamics driven by a cellular automaton including environmental factors of the landscape, with a social model in which we incorporated agents (farmers) potentially transporting and spreading the pest through displacements among villages. Results of model simulation revealed that both agents\' movements and knowledge had a significant, non-linear, impact on invasion spread, confirming previous works on disease expansion by epidemiologists. However, heterogeneity in knowledge among agents had a low effect on invasion dynamics except at high levels of knowledge. Evaluations of the training sessions using ABM suggest that farmers would be able to better manage their crop after our implementation. Moreover, by providing farmers with evidence that pests propagated through their community not as the result of isolated decisions but rather as the result of repeated interactions between multiple individuals over time, our ABM allowed introducing them with social and psychological issues which are usually neglected in integrated pest management programs.Socio-Ecological Systems, Farmers, Invasive Pest, Long Distance Dispersion, Teaching

Conception par simulation pour la conduite de culture

L'optimisation à base de simulation est une approche performante pour la résolution de problèmes d'optimisation continus et stochastiques. Nous proposons des algorithmes d'optimisation par simulation basés sur la décomposition hiérarchique de l'espace de recherche en espaces de plus petite taille. Les problématiques consistent à évaluer les sous espaces, sélectionner les sous espaces optimaux et les diviser à nouveau. Nous discutons l'efficacité d'alternatives algorithmiques connues et d'autres nouvelles, dans le but de trouver la ou l'ensemble des régions optimales. Ces alternatives sont développées dans les contextes d'optimisation de l'espérance, d'optimisation du quantile et d'optimisation multiobjectif. Tout au long de la thèse, nous avons évalué cette famille d'algorithmes sur des problèmes de conception de stratégies de conduite de culture en agriculture et plus particulièrement sur un problème de gestion de l'irrigation du maïs. Nous avons proposé les espaces de décision obtenus par l'application de nos méthodes, et leur traduction en termes de stratégies d'irrigation. Les algorithmes d'optimisation du quantile et d'optimisation multiobjectif ont abouti à la proposition de stratégies nouvelles en termes de prise en compte de l'incertain et de prise en compte simultanée d'objectifs. Il sera intéressant de poursuivre ces pistes de recherche, en particulier pour l'application à d'autres problèmes multicritères soumis à l'incertain.Simulation-based optimization is an efficient approach to resolve stochastic problems with continuous input variables. We introduced three algorithms based on hierarchical decomposition procedure. They aim at partitioning the decision space into smaller ones, and continuing the research into the potentially optimal ones. The main issues are to evaluate regions of continuous decision variables, divide one region into smaller ones, and select one region among all as the one that the algorithm will investigate further. We discuss the efficiency of existing and new methods in order to define the set of small regions optimizing the expected value of performance measures simulated. The best combination is set, and we extend the algorithm to the quantile optimization and multiobjective optimization. We tested all these algorithms on a crop management design problem which deals mainly with corn irrigation in the south west of France. We proposed optimal decision spaces reached with the three algorithms, and translated these spaces into irrigation management policies. Quantile optimization and multiobjective optimization provided new irrigation policies in regard to a different uncertainty point of view, and the consideration of simultaneous multiple objectives. Yet, it will be interesting to lead the research further, especially in the resolution of optimization problems facing both uncertainty and multiple objectives

Economic Implications of a Changing Climate on Smallholder Pineapple Production in Ghana

Pineapple production in Ghana plays a major role in developing the economy through socioeconomic impacts and export. Climatic variations contribute to variable yield and subsequently affect pineapple productivity. Direct dependence on climate for pineapple production could have significant economic implications.  This study examined the economic impact of a changing climate on smallholder pineapple farming in Ghana.  Data from 400 pineapple farmers was obtained from four pineapple growing districts using a two-stage sampling technique. Ricardian regression approach was used to estimate the relationship between farmer’s net farm revenue per hectare, climate and other control variables such as soil and socio economic characteristics. The results revealed negative economic effect between rainfall and net revenue during vegetative stage of pineapple production as well as temperature and net revenue during the flowering stage. A positive effect between net revenue and temperature during yield formation stage was also observed. The study again discovered a fall in net revenue if temperature increases by 1°C and a rise in net revenue if rainfall increases by 1mm during production. The other variables that were key to net revenue were production on Dystric Planosols soil type, access to credit and membership of farmer-based associations. Given the role of pineapple production in the Ghanaian economy, supporting and promoting adaptation options to address issues of climate variability and change is recommended for improved productivity to sustain the pineapple industry economically. Keywords: Net revenue, temperature, rainfall, pineapple production, Ghan

Investigating the potential impact of 1.5, 2 and 3 °C global warming levels on crop suitability and planting season over West Africa

West African rainfed agriculture is highly vulnerable to climate variability and change. Global warming is projected to result in higher regional warming and have a strong impact on agriculture. This study specifically examines the impact of global warming levels (GWLs) of 1.5°, 2° and 3 °C relative to 1971–2000 on crop suitability over West Africa. We used 10 Coupled Model Intercomparison Project Phase5 Global Climate Models (CMIP5 GCMs) downscaled by Coordinated Regional Downscaling Experiment (CORDEX) Rossby Centre’s regional Atmospheric model version 4, RCA4, to drive Ecocrop, a crop suitability model, for pearl millet, cassava, groundnut, cowpea, maize and plantain. The results show Ecocrop simulated crop suitability spatial representation with higher suitability, observed to the south of latitude 14°N and lower suitability to its north for 1971–2000 for all crops except for plantain (12°N). The model also simulates the best three planting months within the growing season from September-August over the past climate. Projected changes in crop suitability under the three GWLs 1.5–3.0 °C suggest a spatial suitability expansion for legume and cereal crops, notably in the central southern Sahel zone; root and tuber and plantain in the central Guinea-Savanna zone. In contrast, projected decreases in the crop suitability index value are predicted to the south of 14°N for cereals, root and tuber crops; nevertheless, the areas remain suitable for the crops. A delay of between 1-3 months is projected over the region during the planting month under the three GWLs for legumes, pearl millet and plantain. A two month delay in planting is projected in the south, notably over the Guinea and central Savanna zone with earlier planting of about three months in the Savanna-Sahel zones. The effect of GWL2.0 and GWL3.0 warming in comparison to GWL1.5 °C are more dramatic on cereals and root and tuber crops, especially cassava. All the projected changes in simulated crop suitability in response to climatic variables are statistically significant at 99% confidence level. There is also an increasing trend in the projected crop suitability change across the three warming except for cowpea. This study has implications for improving the resilience of crop production to climate changes, and more broadly, to food security in West Africa

A Global Systematic Review of Improving Crop Model Estimations by Assimilating Remote Sensing Data: Implications for Small-Scale Agricultural Systems

There is a growing effort to use access to remote sensing data (RS) in conjunction with crop model simulation capability to improve the accuracy of crop growth and yield estimates. This is critical for sustainable agricultural management and food security, especially in farming communities with limited resources and data. Therefore, the objective of this study was to provide a systematic review of research on data assimilation and summarize how its application varies by country, crop, and farming systems. In addition, we highlight the implications of using process-based crop models (PBCMs) and data assimilation in small-scale farming systems. Using a strict search term, we searched the Scopus and Web of Science databases and found 497 potential publications. After screening for relevance using predefined inclusion and exclusion criteria, 123 publications were included in the final review. Our results show increasing global interest in RS data assimilation approaches; however, 81% of the studies were from countries with relatively high levels of agricultural production, technology, and innovation. There is increasing development of crop models, availability of RS data sources, and characterization of crop parameters assimilated into PBCMs. Most studies used recalibration or updating methods to mainly incorporate remotely sensed leaf area index from MODIS or Landsat into the WOrld FOod STudies (WOFOST) model to improve yield estimates for staple crops in large-scale and irrigated farming systems. However, these methods cannot compensate for the uncertainties in RS data and crop models. We concluded that further research on data assimilation using newly available high-resolution RS datasets, such as Sentinel-2, should be conducted to significantly improve simulations of rare crops and small-scale rainfed farming systems. This is critical for informing local crop management decisions to improve policy and food security assessments

Manganese-salicyloximate clusters stating from [MnII(hfacac)2]: from Mn4 to Mn12

The systematic exploration of the reactivity of [Mn(hfacac)2] with R‐salicyloximes (R‐saloxH2: R = H, Me, Et) yielded a family of clusters with nuclearities ranging from Mn4 to Mn12. The compounds with formula [Mn6(O)2(salox)6(CF3COO)2(EtOH)4] (1 ) and [Mn12(salox)12(O)4(N3)4(H2O)2(MeOH)6] (4 ) show two or four linked {Mn(µ3‐O)(salox)3}+ triangular subunits. Magnetic measurements revealed spin ground states of S = 4 for 1 and S = 8 for 4 , as well as single‐molecule magnet responses and magnetic hysteresis above 2 K. The cubic [Mn4(Mesalox)4(MesaloxH)4] (2 ), the hexanuclear [Mn6(Etsalox)6(O)2(MeO)4(MeOH)2] (3 ) and the octanuclear [Mn8(Mesalox)6(O)2(N3)6(MeOH)8] (5 ) are polymorphs of previously reported systems. Small structural changes allows an S = 11 ground state for 3

Human hydroxytyrosol's absorption and excretion from a nutraceutical

Among the various (poly)phenols that are being sold as such or as part of a more complex mixture, hydroxytyrosol (HT) is the only one that bears a European Food Safety Authority health claim. Therefore, several HT-based products are being developed and sold and it becomes necessary to evaluate its accessibility following ingestion. Twenty-one volunteers were recruited for a randomized, crossover, placebo-controlled, and double-blind intervention study.We performed a Latin square design: after one-week washout, i.e. olive-free diet, subjects were randomly assigned to the placebo (maltodextrin), 5, or 25 mg/day HT group. Twenty-four hour urine samples were collected after the intervention week, and baseline urines were collected the week before the study and during periods of washout. The results show that HT given as the foremost component of a nutraceutical preparation is bioavailable and is recovered in the urine chiefly as sulphate-3′

Simulating the impact of climate change on maize production in Ethiopia, East Africa

Background: Climate change is expected to signifcantly impact agricultural production across Africa. While a number of studies assessed this impact in semi-arid southern Africa, or tropical West Africa, only a limited number took interest in the mountainous and climatically varying Ethiopia of eastern Africa. This study assesses the impact of climate change on maize production in three representative sites of maize growing areas in Ethiopia. The assessment relies on the DSSAT crop model simulation of maize under current climate and future projections (19 Global Climate Models and 2 Representative Concentration Pathways). The period 1980–2010 was used to represent the baseline climate, while future climate projections cover three periods; near term (2010–2039), mid-century (2040–2069) and end-of-century (2070–2099). Climate, soil and crop management data were collected for the study sites representing the maize growing areas in the country. Results: Results show that maize yields will decrease by up to 43 and 24% by the end of the century at Bako and Melkassa stations, respectively, while simulated maize yield in Hawassa show an increase of 51%. On the one hand, rainfall variability and rising temperatures are determining factors explaining yield decrease in Bako and Melkassa, while projected rainfall increase in Hawassa explain simulated yield increases. Conclusion: The terrain and climate high variability of Ethiopia is emphasizing the extremely diferent responses of current agricultural systems to climate change. Though adaptation approached can address some negative impacts, and in some case can take advantage of changes, this study reveals that dedicated local knowledge is necessary for national and regional decision makers to respond with local relevance to a global exposure, in order to face food security challenges

Cost and benefit analysis of adopting climate adaptation practices among smallholders: The case of five selected practices in Ghana

Smallholder farmers mostly depend on agriculture for their sustenance yet the sector is threatened by changing climate. It is essential for smallholders to adapt to reduce their vulnerability. Estimating the economic effectiveness of climate adaptation practices would enhance planning and actions among stakeholders and consequently impact policy. This study conducted an ex-ante in-depth empirical analysis of the costs and benefits of implementing five climate adaptation strategies identified among smallholder horticultural farmers in Ghana. A total of 180 smallholder households who have implemented the identified practices in two horticultural cropgrowing municipalities were surveyed. Profitability indicators, evaluation of environmental and social externalities were employed to comparatively estimate the cost-effectiveness of the practices. The results indicated that, from private and public perspectives, implementing any of the five adaptation practices would yield positive benefits. However, considering the capital required, payback period for investments made and risks from implementation, two out of the five practices are particularly fitting choices for the smallholders. Institutional and policy support is desirable if all the practices are to be adopted. To broaden information on potential of climate adaptation vis-a-vis ` climatic effects with economic analysis, the study proposes integrating localized climate vulnerability and economic assessments for enhanced climate adaptation actions