Bee health and sustainable pollination While developing synergies with ongoing activities at EU level, the research will focus on hazard identification for managed and wild bees, social and solitary bees, focusing mainly on exposure and risk characterisation of mixtures of chemicals for bee health. It will take into account the presence or absence of main pathogens, notably Varroa destructor, Nosema spp, American Foulbrood, DWV, and will develop molecular markers using omics technologies. Moreover, it will also take into account the aspect of nutrition and its interplay with the other two stress factors since it has been shown that quality of diet plays an important role in bee health.The level of contamination in relevant bee matrices (nectar, pollen, royal jelly and beeswax for social bees) and environmental compartments (e.g. on flowering plants and in the nest of bees, whether managed or wild) will be determined. The driving factors and processes leading to such contamination, and their relative and synergistic contribution to final contamination levels and its impact on bee health will be systematically identified. Data on food intake in bees for exposure assessment by ingestion and to understand their effects versus potential residues on environment should also be generated.The toxicological effect (whether additive, synergistic or antagonistic) of the most commonly found chemical compounds in agriculture in the EU (e.g. pesticides, veterinary medicinal products, other contaminants) will be investigated. A range of representative bee types (honeybee subspecies and bumblebee and solitary bee species) will be considered. Bees of different life stages (larvae and adults) genders and casts (including queens) will be tested. Adverse (lethal, chronic and sublethal) effects, including potential buffer/compensation effects at colony/population level, will be assessed. Work will include, as necessary, development and validation of relevant test protocols. Data on toxicokinetics and toxicodynamics in bees will be generated. Full dose-response relationships will be made to derive bee toxicological thresholds considering species specific sensitivity distributions. Finally, omics data will be developed and validated in the field to provide further insights on species sensitivity at the molecular level and ultimately to determine markers of chemical and pathogen exposure/effects to be used in monitoring plans.Projects should fall under the concept of the 'multi-actor approach'[[See definition of the 'multi-actor approach' in the introduction to this Work Programme part.]]. The projects should ensure appropriate dissemination to the breeding and professional sectors and other relevant stakeholders to facilitate uptake of results. There should be cooperation as appropriate with relevant initiatives, e.g. in the context of MUST-B, and other funded projects in this field, e.g. those selected under SFS-28-2017.The Commission considers that proposals requesting a contribution from the EU of up to EUR 9 million would allow this specific challenge to be addressed appropriately. Nonetheless, this does not preclude the submission and selection of proposals requesting other amounts. Bees (including managed and wild bees, social and solitary bees) are subject to numerous pressures in the modern world, in particular loss of habitats which affects their nutrition, exposure to various chemicals (including an array of agrochemicals) and various pathogens. Stressors do not necessarily act in isolation, but in combination, and their effects in isolation or interactions may differ between geographical areas and be more or less severe in different bee species. Regulatory measures in place and beekeeping or agricultural practices do not currently address or prevent the possible effect of such complex interactions. Understanding interactions of multiple stressors constitutes a major scientific challenge, since testing and control in natural conditions is required. Our understanding of the underlying mechanisms and how to interpret them to discern trends and understand the biology of a healthy bee population/colony and its interaction with the stress factors is still limited. Previous and on-going EU projects have sought to shed some light in particular areas. The European Food Safety Authority (EFSA) and the EU reference laboratory (EURL) for bee health are addressing more focused aspects of a holistic risk assessment of multiple stressors in honeybees in the MUST-B project.Our ability to understand and mitigate the bee health stressors is still limited and so is our capacity to ensure healthy bee populations, sustainable beekeeping and the provision of adequate pollination services in the EU. To move forward, several research topics still need to be addressed. The assessment of potentially harmful effects of chemicals (e.g. agrochemicals and veterinary medicinal products) or mixtures of chemicals and its interactions with other stressors and the monitoring of bees and pollination services to detect and assess long term effects still needs to be addressed. Filling gaps of knowledge on hazards, focusing mainly on (chronic and sub) lethal effects of mixtures of chemicals on both healthy and infected bees at population and/or colony levels, while also taking into account the aspect of bee nutrition and its effect on bee health. Provide science- based protocols for improvement of bee regulatory testing schemes. Contribute to the consolidation of validated monitoring plans on bee health with the development and use of molecular markers. Contribute to sustainable pollination and sustainable beekeeping.