Efecto del polen nativo chileno y sus compuestos en abejas infectadas con la variante DWV-A del virus de las alas deformadas
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Date
2026
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Universidad de Concepción
Abstract
La salud de las abejas melíferas (Apis mellifera) se ve afectada por la interacción de múltiples estresores, entre los cuales las infecciones virales cumplen un rol central. El virus de las alas deformadas (DWV) es uno de los patógenos más prevalentes, especialmente por su asociación con Varroa destructor y su capacidad de persistir como infección subclínica. Su patogenicidad no depende únicamente de la exposición viral, sino que está fuertemente modulada por el estado nutricional y fisiológico del hospedero. En este contexto, el polen emerge como un factor clave de resiliencia, capaz de influir en la carga viral, la sobrevivencia y la respuesta inmune frente a la infección. En este estudio se evaluó el efecto de distintas dietas polínicas y de compuestos bioactivos asociados al polen sobre la infección por DWV-A en abejas melíferas. En una primera etapa, se caracterizaron pólenes monoflorales y poliflorales provenientes de plantas nativas y exóticas de Chile, con énfasis en su composición fitoquímica. Posteriormente, se evaluó el efecto de estas dietas sobre parámetros de infección viral, sobrevivencia y respuesta inmune en abejas inoculadas experimentalmente con DWV-A. Finalmente, se analizó el efecto de un compuesto fenólico seleccionado sobre el desempeño cognitivo de las abejas infectadas. Los pólenes utilizados fueron colectados durante la temporada apícola 2022 en apiarios experimentales ubicados en Chillán y Coihueco (Región de Ñuble) y en Río Bueno (Región de Los Ríos), mientras que los ensayos biológicos se realizaron con abejas provenientes del apiario experimental de la Estación de Investigación “El Nogal” de la Universidad de Concepción, en Chillán, Chile. En términos de caracterización química, el polen monofloral de Eucryphia cordifolia presentó las mayores concentraciones de compuestos fenólicos y flavonoides, incluyendo ácido gálico, ácido vainílico, ácido clorogénico, ácido cafeico, quercetina y kaempferol, en comparación con Rubus ulmifolius y el polifloral. En los ensayos biológicos, las dietas basadas en polen redujeron significativamente la carga viral en abejas inoculadas con DWV-A, con efectos dependientes del tipo de polen. El polen monofloral de E. cordifolia produjo la mayor reducción de carga viral (de 1,0 × 10¹³ a 1,0 × 10⁵ copias por abeja) y la mayor tasa de sobrevivencia (91 %), mientras que los pólenes de R. ulmifolius y polifloral también disminuyeron la carga viral, aunque en menor magnitud. A nivel inmunológico, las dietas polínicas modularon la expresión de genes asociados a las vías Toll, Imd y RNAi, con una disminución de la expresión de Cactus y un aumento de Dorsal, Relish y Dicer-like, respectivamente. Siguiendo esta línea, se evaluó el efecto del ácido clorogénico como compuesto bioactivo representativo, mediante la técnica de Respuesta de Extensión de la Probóscide (PER). La suplementación con ácido clorogénico atenuó los efectos negativos asociados a la infección por DWV-A de manera dependiente de la concentración, mejorando la sobrevivencia y el aprendizaje asociativo. En particular, la sobrevivencia de las abejas infectadas aumentó significativamente, alcanzando valores comparables al control no inoculado en la dosis más alta evaluada. En contraste, las mejoras en aprendizaje y memoria fueron más evidentes a concentraciones intermedias, sugiriendo una respuesta cognitiva no lineal. Estos resultados evidencian que la calidad fitoquímica del polen y sus compuestos bioactivos pueden modular significativamente la dinámica de infección por DWV-A, la respuesta inmune y el desempeño cognitivo en abejas melíferas. Estos hallazgos abren la posibilidad de desarrollar estrategias nutricionales basadas en recursos florales nativos para fortalecer la resiliencia de colonias frente a patógenos virales, con potencial aplicación en manejo apícola sostenible.
The health of honey bees (Apis mellifera) is affected by the interaction of multiple stressors, among which viral infections play a central role. Deformed wing virus (DWV) is one of the most prevalent pathogens, particularly due to its association with Varroa destructor and its ability to persist as a subclinical infection. Its pathogenicity does not depend solely on viral exposure but is strongly modulated by the host’s nutritional and physiological status. In this context, pollen emerges as a key resilience factor capable of influencing viral load, survival, and immune responses to infection. In this study, the effect of different pollen-based diets and pollen-associated bioactive compounds on DWV-A infection in honey bees was evaluated. In the first stage, monofloral and polyfloral pollens from native and exotic plant species in Chile were characterized, with emphasis on their phytochemical composition. Subsequently, the effects of these diets on viral infection parameters, survival, and immune response were assessed in bees experimentally inoculated with DWV-A. Finally, the effect of a selected phenolic compound on the cognitive performance of infected bees was analyzed. The pollen samples were collected during the 2022 beekeeping season from experimental apiaries located in Chillán and Coihueco (Ñuble Region) and Río Bueno (Los Ríos Region), while biological assays were conducted using bees from the experimental apiary of the “El Nogal” Research Station of the University of Concepción in Chillán, Chile. Regarding chemical characterization, monofloral pollen from Eucryphia cordifolia exhibited the highest concentrations of phenolic compounds and flavonoids, including gallic acid, vanillic acid, chlorogenic acid, caffeic acid, quercetin, and kaempferol, compared with Rubus ulmifolius and polyfloral pollen. In biological assays, pollen-based diets significantly reduced viral load in DWV-A-inoculated bees, with effects depending on pollen type. E. cordifolia pollen showed the greatest reduction in viral load (from 1.0 × 10¹³ to 1.0 × 10⁵ copies per bee) and the highest survival rate (91%), while R. ulmifolius and polyfloral diets also reduced viral load, albeit to a lesser extent. At the immune level, pollen diets modulated the expression of genes associated with the Toll, Imd, and RNAi pathways, downregulating Cactus and upregulating Dorsal, Relish, and Dicer-like, respectively. Following this line of evidence, chlorogenic acid was evaluated as a representative bioactive compound using the Proboscis Extension Response (PER) assay. Chlorogenic acid supplementation attenuated the negative effects associated with DWV-A infection in a dose-dependent manner, improving both survival and associative learning. Survival of infected bees increased significantly, reaching levels comparable to the non-inoculated control at the highest dose tested. In contrast, improvements in learning and memory were more pronounced at intermediate concentrations, suggesting a non-linear cognitive response. These results demonstrate that the phytochemical quality of pollen and its bioactive compounds can significantly modulate DWV-A infection dynamics, immune responses, and cognitive performance in honey bees. These findings open the possibility of developing nutrition-based strategies using native floral resources to enhance colony resilience against viral pathogens, with potential applications in sustainable beekeeping management.
The health of honey bees (Apis mellifera) is affected by the interaction of multiple stressors, among which viral infections play a central role. Deformed wing virus (DWV) is one of the most prevalent pathogens, particularly due to its association with Varroa destructor and its ability to persist as a subclinical infection. Its pathogenicity does not depend solely on viral exposure but is strongly modulated by the host’s nutritional and physiological status. In this context, pollen emerges as a key resilience factor capable of influencing viral load, survival, and immune responses to infection. In this study, the effect of different pollen-based diets and pollen-associated bioactive compounds on DWV-A infection in honey bees was evaluated. In the first stage, monofloral and polyfloral pollens from native and exotic plant species in Chile were characterized, with emphasis on their phytochemical composition. Subsequently, the effects of these diets on viral infection parameters, survival, and immune response were assessed in bees experimentally inoculated with DWV-A. Finally, the effect of a selected phenolic compound on the cognitive performance of infected bees was analyzed. The pollen samples were collected during the 2022 beekeeping season from experimental apiaries located in Chillán and Coihueco (Ñuble Region) and Río Bueno (Los Ríos Region), while biological assays were conducted using bees from the experimental apiary of the “El Nogal” Research Station of the University of Concepción in Chillán, Chile. Regarding chemical characterization, monofloral pollen from Eucryphia cordifolia exhibited the highest concentrations of phenolic compounds and flavonoids, including gallic acid, vanillic acid, chlorogenic acid, caffeic acid, quercetin, and kaempferol, compared with Rubus ulmifolius and polyfloral pollen. In biological assays, pollen-based diets significantly reduced viral load in DWV-A-inoculated bees, with effects depending on pollen type. E. cordifolia pollen showed the greatest reduction in viral load (from 1.0 × 10¹³ to 1.0 × 10⁵ copies per bee) and the highest survival rate (91%), while R. ulmifolius and polyfloral diets also reduced viral load, albeit to a lesser extent. At the immune level, pollen diets modulated the expression of genes associated with the Toll, Imd, and RNAi pathways, downregulating Cactus and upregulating Dorsal, Relish, and Dicer-like, respectively. Following this line of evidence, chlorogenic acid was evaluated as a representative bioactive compound using the Proboscis Extension Response (PER) assay. Chlorogenic acid supplementation attenuated the negative effects associated with DWV-A infection in a dose-dependent manner, improving both survival and associative learning. Survival of infected bees increased significantly, reaching levels comparable to the non-inoculated control at the highest dose tested. In contrast, improvements in learning and memory were more pronounced at intermediate concentrations, suggesting a non-linear cognitive response. These results demonstrate that the phytochemical quality of pollen and its bioactive compounds can significantly modulate DWV-A infection dynamics, immune responses, and cognitive performance in honey bees. These findings open the possibility of developing nutrition-based strategies using native floral resources to enhance colony resilience against viral pathogens, with potential applications in sustainable beekeeping management.
Description
Tesis presentada para optar al grado de Doctor/a en Ciencias de la Agronomía.