Biology subjects

Radici, A.

Publications and source records attributed to Radici, A..

9 recordsLinked to original sources

bioRxiv2026

Modeling mosquito control strategies and their effect on pathogen transmission

The mosquito Aedes albopictus is a competent vector for the transmission of several arboviruses and is currently spreading across many continents. Since conventional control methods, like insecticides, often lead to environmental problems and the emergence of resistance, scientists developed alternative mosquito control strategies. One of the most used is the Sterile Insect Technique (SIT), which involves the mass release of males sterilized through irradiation. The Toxic Male Technique (TMT) is instead based on the release of genetically modified males expressing toxic proteins that kill females when they mate. Control strategies are often intended as methods to eradicate mosquito populations, yet a less ambitious and more cost-effective task is to reduce them such that the probability of transmission of viruses to humans becomes negligible. To compare the efficacy of these control strategies, we develop a mathematical model with two communicating compartments: a mosquito population and epidemiological model coupled with a human epidemiological model. As a proof-of-concept, we test the model using meteorological and entomological data for the Emilia-Romagna region. Our results indicate that the TMT strategy is more effective in lowering the probability of transmission and provides indication for the deployment of control strategies.

ecology↗

bioRxiv2026

Aedes albopictus and dengue transmission risk in France over the 21st century

Climate change is dramatically affecting species distribution and phenology worldwide. Its impact on arthropod vectors, such as the Aedes albopictus mosquito, has important consequences for biting nuisance and arbovirus transmission risk. Here, we assess the impact of climate change on the presence and abundance of Ae. albopictus, as well as the risk of dengue transmission over France during the 21st century. We use a mechanistic model that we adjusted against records of recent autochthonous cases of dengue in France. We simulate climatic suitability indicators, such as the adult abundance during the activity period, epidemic risk and secondary cases of dengue under different climatic and demographic scenarios at different periods up to 2085. Future simulations are based on a high-pressure scenario (high greenhouse gas emissions, high demographic growth) and a median-pressure scenario (median greenhouse gas emissions, demographic stagnation). To account for climate model uncertainty, we repeat the simulations for three different regional climate models. By 2085, in the high-pressure scenario, most of France (89-96%) will be climatically suitable for the establishment of Ae. albopictus, with the exception of mountain ranges. Similarly, autochthonous transmission of dengue will be theoretically possible in all colonized areas except over northern lowlands (71-95%). In the median pressure scenario, both climatic suitability for establishment (49-89%) and autochthonous dengue transmission risk (31-82%) exhibit large variation. Low population density areas show moderate suitability for vector establishment but exhibit the highest potential for dengue transmission. Overwintering mechanisms, such as egg diapause, indispensable for survival in temperate climates, may not be necessary along the Mediterranean and Basque coasts, allowing activity of the vector all year-round in the future.

ecology↗

bioRxiv2025

Temperature is the key weather determinant of Aedes albopictus seasonal activity in southern France

The presence and the activity of Aedes albopictus are a growing concern for nuisance and public health in Europe. Vector control operators, public health officers, and communities look for weather-based decision support systems to inform mosquito management policies. Despite an increasing number of entomological and modelling studies, our incomplete understanding of mosquito population response to weather drivers in natural conditions restricts the development of sound vector management policies. Here, we aim to clarify the role of weather conditions on Ae. albopictus presence and abundance in four sites in southwestern France. We rely on ovitrap longitudinal records collected on a 1-2 weeks basis and weather time series over 2023 and 2024 to model oviposition activity. Our analysis combines a mechanistic model from literature and a new machine learning model fitted on cross-correlated lagged weather predictors. Both models satisfactorily reproduce the observed oviposition dynamics, correctly predicting the onset and the end of the activity - periods that existing models have often inadequately captured. Temperature plays a major role in triggering the presence of Ae. albopictus, explaining the interannual variation of oviposition in all sites, especially in spring and autumn. In fact, warm springs and autumns extend the periods in which Ae. albopictus life-history traits (fertility, development, survival) approach their thermal optima. In summer, a more prominent role of rain and humidity emerges among secondary drivers of oviposition intensity. This work contributes to the development of operational weather-driven forecasting tools for Ae. albopictus activity to support vector control operations in different biogeographical contexts.

ecology↗

bioRxiv2025

Aedes albopictus is rapidly invading its climatic niche in France: wider implications for biting nuisance and arbovirus control in Western Europe

The Asian tiger mosquito, Aedes albopictus, is a competent vector of arboviruses, such as dengue. After its introduction into southern Europe, this invasive species has been rapidly spreading as well as causing autochthonous cases of arboviral diseases. Both Ae. albopictus presence and potential to transmit arboviruses are facilitated at warm temperatures, hence global warming is expected to affect their presence in temperate regions. We use a climate- and environmental-driven mechanistic modelling framework to investigate the impact of recent climate change on Ae. albopictus range expansion and its potential to transmit dengue in Western Europe. We simulate climatic suitability, adult density and dengue transmission risk which we compare with a large ensemble of entomological and epidemiological observations over the past 20 years. Most importantly, we analyze a novel spatiotemporal dataset of colonized municipalities in metropolitan France to estimate the spread rate of Ae. albopictus and compare it with model predictions. Lastly, we analyze the sensitivity of entomological and epidemiological risk to changes in temperature, rainfall and human density. Distribution of simulated mosquito populations and dengue transmission risk satisfactorily match entomological and dengue observations for Western Europe (AUC = 0.90 and 0.75 respectively). While lowlands in southern Europe were already climatically suitable for hosting Ae. albopictus around 2010, Western France, together with large populated cities, such as London, Zagreb and Vienna, have become suitable recently. Importantly, the accelerating colonization of Ae. albopictus in France may be approaching the limit of its theoretical climatic niche; future expansion will depend on the climate-driven enlargement of suitable areas. Area at risk of dengue transmission has recently expanded from the Mediterranean coasts over northern Spain and Western France. The sensitivity analysis suggests that climate change may expose medium-sized cities to the highest epidemiological risk; this finding is consistent with recently reported dengue outbreaks in Europe.

ecology↗

bioRxiv2024

Optimizing fungicide deployment in a connected crop landscape while balancing epidemic control and environmental sustainability

Bioaggressors cause significant losses in crop production, and the efficacy of control methods, primarily based on chemical compounds, comes with considerable environmental and health costs. Plant protection practices implemented locally undermine the mobility of bioaggressors, which can spread between fields, connecting different crop populations. As a consequence, the yield in a given field depends also on the management of connected fields. In this study, we evaluate the efficiency of different fungicide deployment strategies across a national-scale agriculture landscape, balancing the conflicting objectives of maximizing crop production and reducing fungicide use. We use a climate-driven metapopulation model describing the dynamics of the peach (Prunus persica)-brown rot (caused by Monilinia spp.) pathosystem in continental France. Fungicide deployment strategies are based on indices or algorithms, considering network topology, epidemic risk, territory, and stochastic sampling, which prioritize sites to be treated first. Eventually, we focus solely on the objective of maximizing harvest revenue, assuming that untreated fruit can be marketed at higher prices. The optimal strategy depends on the treatment allocation threshold: if up 20% of the area is treated, epidemic risk provides the most effective prioritization. If more than 40% of the area can be treated, a combination of random sampling and risk-based prioritization proves optimal. When considering a single objective, we find that the higher the consumers willingness to pay for untreated fruit, the larger the proportion of untreated sites becomes. Fungicide use could be avoided if untreated fruit were sold at 2.9 times the price of treated fruit.

ecology↗

bioRxiv2023

Phenological and epidemiological impacts of climate change on peach production

Agricultural food security is threatened by climate change impacts, which can distress crop growth and favor the spread of infectious diseases. Here, we examined the synergism of the two potentially most disruptive causes of future yield failure in peach production: the effects of global climate change on fruit growth and on the spread of fungal diseases. Coupling a phenological and epidemiological model across the French continental territory, we provided projections of yield losses for four peach cultivars (early, mid-early, mid-late, and late) in the XXI century under different climate change scenarios. Global warming is expected to impair fruit phenology with blooming failure events in the south-western part of the country. This will be less extreme under the more moderate emission scenario, even though sporadic blooming failures will still occur. In contrast, future warmer and drier conditions will decrease brown rot-induced yield loss in the historical locations devoted to peach cultivation. To adapt to these changes, the benefits of shifting peach production sites to new suitable areas are evaluated. Thanks to this strategy, the peach national yield could still be fulfilled even under the most extreme climate change scenario. Comprehensive mathematical frameworks, that concomitantly consider the climatic effects on the plant hosts and on their pathogens, are required to provide reliable future predictions of crop yields and to inform control and adaptation strategies to guarantee food security under global warming.

ecology↗

bioRxiv2023

A metapopulation framework integrating landscape heterogeneity to model an airborne plant pathogen: the case of brown rot of peach in France

Plant disease dynamics are driven by the concurrent interplay of host susceptibility, pathogen presence, and environmental conditions. While host susceptibility and local environmental conditions can readily be characterised, the transmission of an airborne pathogen depends on the biotic and abiotic conditions of the surrounding environment. Here, we propose an original metapopulation framework integrating landscape heterogeneity, in terms of climate and host density, where local populations of plant hosts are connected via air-masses which allow pathogen dispersal. We explicitly account for climatic drivers affecting pathogen release and survival while modelling aerial dispersal using Lagrangian simulations, as well as host phenology and infection. We calibrate the model parameters according to the literature and using Approximate Bayesian Computation against observations of brown rot incidence in French peach orchards from 2001-2020 across an area of 50,000 km2. We used the model to produce maps of risk, distinguishing site dangerousness (risk of causing secondary infection in other sites) and vulnerability (risk of becoming infected) across the our study area. We find that most dangerous and vulnerable sites are located along the Rhone Valley, due to the concurrence of high density of peach cultivation, a suitable climate and persistent airborne connections. Our work represents a first step to integrate metapopulation theory, epidemiology and air-mass movements to inform plant protection strategies, and could be adapted to optimize crop protection under future climate projections.

ecology↗

bioRxiv2022

Benefits and costs of a global cooperative surveillance strategy to control trans-boundary crop pathogens

Trans-boundary diseases are extremely complex to control and can cause global socioeconomic damages. In the context of crop protection, surveillance strategies are usually designed according to administrative boundaries. In this study, we investigate to which extent this geographical scale of surveillance is suitable for long-distance dispersed pathogens. We lever on a global epidemic network, presented in a previous work, describing worldwide potential transport of P. graminis, the causal agent of stem rust of wheat. We conceive two surveillance strategies: "Country-based" and "Cooperative" and we compare their performances, in terms of minimizing the number of sentinels deployed, to achieve given surveillance targets, both at the global and country level. As expected, we find that a "Cooperative" strategy is more efficient at the global scale, and this is particularly true for intermediate targets of surveillance. However, costs and benefits of adopting a "Cooperative" strategy are not equally distributed among countries. Medium size countries in central Europe and Asia are those that would benefit most from a cooperative strategy. On the other hand, Greece and Finland, having a small wheat production but placed in important Puccinia pathways, are those that should deploy, in the global interest, more sentinels than they would place in the national interest. Among the major wheat producers, China is the only country that would have a cost from a cooperative strategy, while India, Russia, United States, France and Ukraine would have the most benefits. It follows that the acknowledgement of these discrepancies could help to achieve general stakeholder support for a global international cooperative surveillance system.

plant biology↗

bioRxiv2021

Surveillance of airborne plant disease dissemination at continental scale using air mass trajectory analysis and network theory

Sustainable management of plant disease outbreaks in agriculture is one of the main challenges of the next years to restore economic and environmental viability of farming practices. Improving early-detection capabilities and disease surveillance is increasingly seen as an obligate step to design appropriate and effective prophylactic measures. In this context, plant diseases caused by wind-dispersed pathogens represent an interesting case of study, since they are particularly complex and hard to observe directly, especially if compared to other dissemination means, and demand for a multidisciplinary approach to be dealt with. Wind dispersal could imply a geographic differentiation in pathogens spreading potential, due to the emerging of local meteorological features. In this work we analyze the spatio-temporal patterns of wind connectivity in Europe and the Mediterranean basin in order to identify possible pathways of Puccinia graminis spores, the causal agent of stem rust of wheat. By running backwards Lagrangian simulations merging a biological layer coupled with a pathogen viability model, we investigate possible long-distance connections between regions in the study area across different seasons. We characterized these regions in terms of network centrality indicators to identify possible spreaders of stem rust of wheat, founding that Central and Western European regions appears to provide highest connectivity for the spread of P. graminis.

plant biology↗