###### Abstract  
Ingredients rich in phenolic compounds and antioxidants of winemaking wastes, which play an important role in the prevention of various diseases and the control of viruses, are being explored. Currently, there is a concern about honeybee population loss, with deformed wing virus (DWV) being the most common virus infecting apiaries and one of the main causes of honeybee decline. Hence, the effect of grape pomace powder (GPP) as a dietary supplement to enhance the immune system of honeybees affected by DWV was evaluated. The characteristics of the ingredient GPP, obtained by spray-drying, revealed a high anthocyanin content (1102.45 mg 100 g\({}^{-1}\)), and it was applied at doses of 0.5, 1, 2.5 and 5% as a dietary supplement for bees infected by DWV. The results showed that the GPP treatments strengthened the immune response of honeybees against DWV. Moreover, the expression of the Relish gene was significantly higher in bees fed with GPP compared to the infected control. This study, which is framed in the search of food waste valorization for environmental sustainability, proves the feasibility of using grape wastes as dietary supplements for pollinators, and provides knowledge of the influence of polyphenols on the expression profiles of immune-related genes in honeybees. winemaking industry; anthocyanins; _Apis mellifera_; antiviral activity; agro-sustainability; food waste valorization +
Footnote †: journal: _Antioxidants_  
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of these bioactive compounds, demonstrating that these molecules can inhibit adsorption, as well as virus binding and virus entry, integrase, RTase and protease. In addition, they act on the inhibition of replication of DNA and RNA polymerases as well as the formation of protein complexes [7]. Hence, opportunities to reduce food waste and integrate this approach to the entire supply chain and reap the beneficial properties of these bioactive compounds are required. In this sense, the use of new ingredients for pollinators, as proposed in this study, could be a potential alternative for food waste reduction. Similar results were found in a study where they pointed out that there was a response in the genes involved in detoxification in bees fed with sucrose solution enriched by phenolic compounds [8]. The honeybee (_Apis mellifera_ L.) is an important species with a key role in agriculture as a pollinator of plant species. Honeybees are involved in enhancing the biodiversity of agricultural and non-agricultural systems [9]. Therefore, honeybee losses have become a matter of increasing concern worldwide. Deformed wing virus (DWV), which is a widespread virus associated with the spread of the _Varroa destructor_ mite, is considered as one of the most critical factors contributing to bee losses at the global level [10]. The virus causes physical malformations in wings, abdominal swelling, paralysis, and behavioral disturbances in bees. In addition, studies have reported that DWV infection can alter the molecular mechanisms of learning, affecting memorization ability and disrupting the central and peripheral nervous systems [11]. DWV transmission follows several routes, with varying pathogen loads and virulence. This transmission of the virus (DWV) in _A. mellifera_ colonies can occur in two ways. On the one hand, it can be transmitted vertically (from the queen or drone to the offspring). On the other hand, it can be transmitted horizontally through either shared food resources or via trophallaxis [12]. Consequently, viral diseases have demonstrated a negative impact on food security, wildlife and economic stability [13]. Currently, beekeepers have several tools to control the vector of DWV, the Varroa mite. Among the measures, the use of synthetic chemical acaricides or natural repellents, such as essential oils, organic acids and a combination of the use of management practices are included, although they are not sufficiently effective [14].