Cyril Piou

To improve our understanding and management of species’ response to environmental and anthropogenic changes, there is a critical need for integrative modeling approaches that encompass demographic, ecological and evolutionary processes in a unified framework. This is especially crucial for anadromous salmonid fishes that hold significant socio-economic value. Mechanistic models, particularly Demo-Genetic Agent-Based Models (DG-ABMs), are promising tools to address this challenge. Building on previous work, we present IBASAM, an Individual Based Anadromous SAlmonids Model. It incorporates significant advancements, including new processes such as dispersal and in-river movement, enhanced flexibility for simulating diverse spatial configurations- from river dendritic networks to metapopulations and multiple marine areas- and the integration of variation in life history phenology and the genetic architecture of traits. Additionally, a user-friendly interface has been developed to facilitate broader application. This improved versatility enables IBASAM application to a number of populations and species of anadromous salmonids, making it well-suited for a wide range of ecological and evolutionary studies. The model is particularly suited for investigating (meta)population eco-evolutionary dynamics, persistence, and adaptation to environmental changes, as well as exploring management options including fisheries regulation and river connectivity restoration. We summarize the model’s structure and illustrate some of its novelties, parameterization, and emerging patterns with the case study of a naturally reproducing Atlantic salmon population simulated over 100 years, with constant fishing rates and no climatic trend. Our simulations successfully reproduced 30 variables observed over 30 years in the Scorff population. IBASAM opens up new opportunities for research on the response of salmonid meta-populations to environmental changes, the exploration of management practices, with further developments possible.

Oviparous animals often prioritize the allocation of reproductive resources to egg size over clutch size, but the impact of this maternal investment on the allocation of embryonic yolks and its ecological functions is poorly understood. We investigated how desert locust embryos allocate yolk for survival energy after hatching, rather than embryonic somatic growth depending on egg size in response to desiccation stress. Crowd-reared females (gregarious phase) produced significantly larger progeny with higher tolerance to starvation than females reared in isolation (solitarious phase). Abnormally small hatchlings with residual yolk in their gut emerged from small and large eggs when exposed to desiccation. In particular, these small hatchlings of desiccated eggs survived significantly longer under starvation than those of wet ones, with larger eggs providing even greater survival benefits. Physiological analysis showed that hatchlings from desiccated eggs showed a trade-off by reserving more lipids without somatic growth than those from normal eggs. Desiccation could be a reliable signal for embryos to predict future poor vegetation, and reserved energy could increase the chance of accessing food after hatching. Our results underscore adaptive plasticity in maternal and embryonic resource allocation in desert locusts in response to unpredictably variable semi-arid habitats.

BACKGROUND: An innovative version of the sterile insect technique (SIT) for pest control, called boosted SIT, relies on the use of sterile males coated with a biocide to control a target wild pest population of the same species. The objective of the present study was to assess the relevance of such technology to control the fruit fly Bactrocera dorsalis and fruit losses in mango orchards using. An agent‐based simulation model named BOOSTIT was used to explore the reduction of fruit losses thank to sterile male fruit flies control and economic benefits according to different strategies of sterile male release. The simulation considered a landscape of 30.25 ha made up of four mango orchards.RESULTS: The SIT and the boosted SIT reduced fruit losses when releases were made before the mango fruiting period. According to model simulations, releases should be performed at least seven times at 2‐week intervals and with a sterile/wild male ratio of at least 10:1. Considering the benefit/cost ratio (BCR), few releases should be done with a late start date. The BCR showed economic gains from the two control methods, the number of saved fruits and BCR being higher for SIT.CONCLUSION: Our simulations showed that SIT would have better results than the boosted SIT to contribute to an effective control of Bactrocera dorsalis at the scale of a small landscape. We highlight the need for laboratory studies of other types of pathogen to find a suitable one with higher incubation time and lower cost. © 2024 The Author(s). Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Locusts and other migratory grasshoppers are transboundary pests. Monitoring and control, therefore, involve a complex system made up of social, ecological, and technological factors. Researchers and those involved in active management are calling for more integration between these siloed but often interrelated sectors. In this paper, we bring together 38 coauthors from six continents and 34 unique organizations, representing much of the social-ecological-technological system (SETS) related to grasshopper and locust management and research around the globe, to introduce current topics of interest and review recent advancements. Together, the paper explores the relationships, strengths, and weaknesses of the organizations responsible for the management of major locust-affected regions. The authors cover topics spanning humanities, social science, and the history of locust biological research and offer insights and approaches for the future of collaborative sustainable locust management. These perspectives will help support sustainable locust management, which still faces immense challenges such as fluctuations in funding, focus, isolated agendas, trust, communication, transparency, pesticide use, and environmental and human health standards. Arizona State University launched the Global Locust Initiative (GLI) in 2018 as a response to some of these challenges. The GLI welcomes individuals with interests in locusts and grasshoppers, transboundary pests, integrated pest management, landscape-level processes, food security, and/or cross-sectoral initiatives.

Species distribution models (SDM) have become one of the most popular predictive tools in ecology. With the advent of new computation and remote sensing technology, high‐resolution environmental data sets are becoming more and more common predictors in these modelling efforts. Understanding how scaling affects their outputs is therefore fundamental to understand their applicability. Here, we develop a theoretical basis to understand the consequences of aggregating occurrence and environmental data at different resolutions. We provide a theoretical framework, along with numerical simulations and a real‐world case study, to show how these scaling rules influence predictive outputs. We show that the properties of the environment–occurrence relationships change when the data are aggregated: the mean probability of occurrence and species prevalence increases, the optimal environmental values shift and classification rates increase at coarser resolutions up to a certain level. Furthermore, and contrary to the widespread expectation that high‐resolution data would produce better predictions, we show here that model performance may increase using coarser resolution data sets rather than the inverse. Finally, we also show that model performance depends not only on the environment–occurrence relationship but also on the interaction between this and the geography and distribution of the available environment. This theoretical framework helps understanding previously incoherent results regarding SDM upscaling and model performance, and illustrates how theoretical and empirical results can provide important feedbacks to advance in understanding scaling issues in macroecology. The interaction between the shape of the environment–occurrence relationship and the rates of change of the environment is fundamental to understand the effects of upscaling in model performance, and may explain why some models are more difficult to transfer to different regions. Most importantly, we argue that there are conceptual choices related to scaling and SDM fitting that require expert knowledge and further explorations between theory and practice in macroecology.

Lower plant resistance to herbivores following domestication has been suggested as the main cause for higher feeding damage in crops than in wild progenitors. While herbivore compensatory feeding has also been proposed as a possible mechanism for raised damage in crops with low nutritional quality, predictions regarding the effects of plant domestication on nutritional quality for herbivores remain unclear. In particular, data on primary metabolites, even major macronutrients, measured in the organs consumed by herbivores, are scarce. In this study, we used a collection of 10 accessions of wild ancestors and 10 accessions of modern progenies of Triticum turgidum to examine whether feeding damage and selectivity by nymphs of Locusta migratoria primarily depended on five leaf traits related to structural resistance or nutrient profiles. Our results unexpectedly showed that locusts favored wild ancestors over domesticated accessions and that leaf toughness and nitrogen and soluble protein contents increased with the domestication process. Furthermore, the quantitative relationship between soluble protein and digestible carbohydrates was found to poorly meet the specific requirements of the herbivore, in all wheat accessions, both wild and modern. The increase in leaf structural resistance to herbivores in domesticated tetraploid wheat accessions suggested that resource allocation trade‐offs between growth and herbivory resistance may have been disrupted by domestication in the vegetative organs of this species. Since domestication did not result in a loss of nutritional quality in the leaves of the tetraploid wheat, our results rather provides evidence for a role of the content of plants in nonnutritive nitrogenous secondary compounds, possibly deterrent or toxic, at least for grasshopper herbivores.