Animals have developed physiological mechanisms allowing them to respond to ecologically-relevant acute stressors, but whose prolonged activation under chronic stress may lead to exhaustion. In insects, these mechanisms are poorly understood. Since honey bees are insects of uttermost economic and ecological importance that face many stressors, this project aims at characterizing their stress response and identifying its modulating factors. More specifically, we will explore how they respond to a social stress signal, how this response is influenced by season and social context, and whether we can modulate it to limit the impact of chronic stress due to predation by the yellow-legged hornet. Our previous work showed that exposure to a social alarm signal leads to reduced learning, and that this effect is mediated by brain neuropeptides : allatostatins. Yet, not all bees respond in the same way to the signal or to allatostatin injections, meaning that the physiological response is differentially regulated, depending on the season (winter vs. summer) or the individual social role in the colony (e.g. nurses vs. foragers). Our three-partner consortium will use a unique combination of complementary approaches (behavioral assays, functional brain imaging, neuroanatomy, pharmacology, molecular biology, chemistry) in order to address three main objectives: 1) characterize the factors responsible for response variations within the colony; 2) identify the neural and hormonal mechanisms of this plasticity; 3) evaluate how these mechanisms are impacted by chronic predation by hornets, and test strategies to improve bees’ capacity to adapt to this recently emerged major stressor. Hence, this project should bring a breakthrough in our comprehension of bee biology and of its capacity to cope with stress, and should open avenues for possible applications to improve their resilience and welfare.

Nearly 90% of flowering plants depend on pollination making this process a vital ecosystem service for humanity. The sustainable maintenance of pollination services depends primarily on the conservation of wild pollinator populations and the resilience of plant-pollinator interactions to ongoing rapid environmental changes, such as global climate and land use changes. However, management and conservation policies in response to these changes are hindered by the lack of integrative studies on pollination services from plant-insect interactions to livelihood economics, especially in developing countries. We propose to address this issue in a transdisciplinary project focusing on the ivory palm (Phytelephas aequatorialis), a palm endemic to the Ecuadorian Andes that is of economic interest to rural communities and whose pollination success is based on floral thermogenesis. Our hypothesis is that a change in the thermal environment of the palm, triggered by deforestation and climate change, would disrupt plant-pollinator interactions based on floral heat, with cascading effects on palm productivity and the economic benefits of smallholders who depend on it. We will determine how these two anthropogenic stresses could affect plant-pollinator interactions, pollination efficiency, palm genetic diversity and ultimately the benefits to local communities, in order to provide them with optimal and sustainable management strategies for the conservation of ivory palms and pollinators. The project is organized in five work packages (WPs) with across different levels of organization - from the flower to the socio-ecosystem - and combines a range of observational, experimental and modelling approaches. WP1 will detail the mechanisms involved in palm-pollinator interactions, in particular the effect of floral temperatures on the emission of volatile compounds and the role of these floral traits in attracting pollinators and ultimately on palm seed production. WP2 will study how floral traits and pollinators respond to changes in thermal regime, by comparing palm-insect interactions in different environments at the landscape scale. These first two WPs will produce a predictive spatial model of palm productivity based on pollinators. This model will then be combined with socio-economic data obtained in two subsequent WPs. In WP3, an agent-based bio-economic model will be built from surveys and data collected from local communities on their knowledge of palm harvesting and pollination and the surrounding landscape, and socio-economic data on their choices in palm management. This model will help identify, from a collective perspective, sustainable strategies for palm management and pollinator conservation. WP4 will develop role-playing games (RPGs) revolving around the results of the agent-based bio-economic model within a multi-stakeholder platform (farmers, palm product companies, forest conservation NGOs, park rangers) to define locally viable and acceptable ivory palm management strategies at the landscape level. These strategies will then be simulated in the agent-based bio-economic model. Our communication strategy for the project will be deployed in a WP5, and will include, among others, the adaptation of the RPG as an educational tool to support learning objectives in natural resource management for private and governmental institutions in Ecuador.

Climate change impacts plants and animals in various ways, including poleward shifts of their geographical distribution and changes in their phenology (i.e., date of occurrence of life-stages). Our objective is to determine how phenology can shape the spatial distribution of species in a changing climate (warming trend and increased variability). The applied objective is to take into account the changes in phenology to improve pest management methods. Our model species is the pine processionary moth, Thaumetopoea pityocampa, as its range expansion is climatically-driven. We will focus on species phenology on the field in task 1. Data will be collected on sites distributed in different French bioclimate regions and compared to data in the 1970s-1980s. We will also collect data on urbanization gradients to explore the effects of urban heat islands. We will determine microclimate conditions to estimate the temperature that individuals actually experience. Some individuals (from early to late phenologies) will be genotyped to determine whether they come from different populations, since in this case it may explain a larger variability in phenology. In addition, we will conduct experiments in controlled conditions in task 2 to determine the effects of temperature on the development of each biological stage and their thermal limits. With RNA-seq approaches, we will explore differential gene expression when individuals are exposed to heat stress. In task 3, we will develop biophysical models to describe microclimate temperatures. These models will be injected in a phenological model calibrated on data of task 2 and validated on data of task 1. We will then explore cascading effects of climate change based on changes in life-stage cycle and stage-specific constraints. This phenological model will be integrated into a spread model to clearly identify the role of climate change on species distribution via a change in phenology. Task 4 will be dedicated to the interaction with the society: an observer network will be created, a survey will be conducted on the needs of the society and a smartphone application will be developed so that anyone can report phenology events of pine processionary moth. These data from citizen science will allow to retrieve phenological information over a larger territory than our study sites. Lastly, a real-time map will be generated based on weather forecasts to alert about urtication risks related to the occurrence given life-stages (i.e., to protect human and animal health) and to set up biocontrol methods (i.e., to protect plant health) when it is the optimal time. The ambition of this proposal is to provide the very first study about the inter-relation between phenology and distribution in a changing climate. It is based on groundbreaking scientific approaches (e.g., phenological model based on performance curves, combination of phenological and spread models, real-time risk maps, trade-offs for gene expression after heat stress) and innovative field tools (e.g., network of automated connected traps and smartphone application). The applied ambition is also important with operational progresses (higher effectiveness of biocontrol) and it will raise public awareness about local effects of climate change.

Streams are traditionally viewed as receptacles rather than sources of energy with regard to nutrient and energy cycles. However, numerous studies have shown that lakes and rivers are important source of energy for the terrestrial environment, mainly through the emergence of winged aquatic insects, by providing nutritional subsidies to terrestrial consumers. The objective of this project is to evaluate the ecosystem services provided by aquatic ecosystems in adjacent agricultural environments. More precisely, (1) we will focus on three ecosystem services provided and mediated by emerging aquatic insects that are fundamental to agronomy (pollination, foodweb support, and soil fertilization). (2) In parallel to the first objective, we will study the history of the governance of French riparian areas to examine current management practices, their associated representations, and their recent improvements in the governance in order to increase the adoption of ecologically responsible practices by stakeholders. (3) We will map physical and biological characteristics of streams and catchments with high-resolution data and remote sensing techniques to estimate the respective contribution of various drivers (land uses, landscape features, etc.) and spatially exhaustively evaluate the related ecosystems services at multiple scales. To achieve these objectives, we will rely on five sites located along a gradient of agricultural intensification and in different agricultural context. This selection follows a call for collaboration within three Zones Ateliers (ZA Armorique, ZA Loire, ZA Brest-Iroise) from the French Long Term Socio-Ecological Research network (LTSER RZA). The two PIs will be helped is their tasks by 15 other scientists from 11 research units with complementary skills in ecology (plant and animal ecology, foodweb, pollination), geography (remote sensing, spatial modeling, land use planning) and social scientists (ecological economy, management, planning).

In a context of ever-increasing demand for food, the future of farming requires to develop sustainable solutions to produce more food without causing major harmful effects on the environment. In particular, broad-range pesticides and chemical fertilisers need to be phased out in favour of naturally-occurring ecosystem services, such as biocontrol. Among the potential solutions for a sustainable agriculture, the concept of ecological intensification is particularly promising. It hinges on the hypothesis that by acting on populations and diversity of service providers, it is possible to increase the multi-functionality of ecosystems. In agroecosystems, regulation services such as animal pollination and biocontrol of pests by predators and parasitoids are particularly important because they have the potential to maintain or increase crop production while reducing chemical inputs. These services are based not only on key species but also on their trophic interactions. The IMAgHo project aims at harnessing these naturally-occurring interactions to maximise regulatory services in agroecosystems and thus maintain or increase yield while reducing chemical inputs. Key regulatory services will be studied in oilseed rape crop through the deciphering of food web dynamics at very fine temporal scale (monthly sampling), and wide spatial scale (from plot to landscape) in a setting that allows the testing of critical environmental and management gradients. Massively parallel DNA sequencing, and field observations will be used to decrypt food webs and quantify regulatory services of carabids on various pests species, parasitoids attacking aphids and wild and domesticated bees foraging on flowers. Traditionally, food webs are often described as stable states while they are inherently dynamic. Although, the temporal variation in species assemblages and their interactions may strongly impact the delivery of ecosystem services, this remains poorly explored. This is particularly important in agricultural landscapes of annual crops where resources vary greatly throughout the season until the almost complete disappearance of the base of the food web (the primary producer), leading to a drastic reduction of invertebrate populations and consequently a collapse of the food webs. Yet these networks are re-built every year. The dynamics of the selected food webs will be described in oilseed rape fields over a period of two years with samples collected every month during the animals' period of activity in real farming conditions. The mechanisms underpinning the relationship between interaction networks and ecosystem services are still largely unknown. For example, if the biological control of aphids is improved by increasing floral resources in simplified landscapes, this is not always the case in more complex ones. Among the key variables that could explain this context-dependency, agricultural practices, distance from source populations and crop intensification are major elements. IMAgHo will take advantage of the Zone Atelier Plaine & Val de Sèvre (ZA-PVS), which offers a quasi-experimental context to decouple multiple environmental and management gradients and test their respective effect of food webs and regulatory services. The structure and connectedness of the food webs will be analysed in relation to historical data on agricultural practices and biodiversity, which have been recorded on the ZA-PVS for more than 25 years. The ZA-PVS also allows to perform field experiments through existing research partnerships with farmers. Field experiments will be implemented to test how changes in management modify food webs and the related regulation services, and ultimately affect yield. As well as generating fundamental ecological knowledge on ecosystem functioning, this project will produce operational guidelines to limit agrochemical inputs and enhance ecological intensification in agroecosystems.