Nutrigenetic comparison of two Varroa-resistant honey bee stocks fed pollen and spirulina microalgae

Authors: Ricigliano, Vincent; Ihle, Kate; Williams, Steven

Submitted to: Apidologie
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/13/2021
Publication Date: 7/2/2021
Citation: Ricigliano, V.A., Ihle, K.E., Williams, S.T. 2021. Nutrigenetic comparison of two Varroa-resistant honey bee stocks fed pollen and spirulina microalgae. Apidologie. 1-14. https://doi.org/10.1007/s13592-021-00877-3.
DOI: https://doi.org/10.1007/s13592-021-00877-3

Interpretive Summary: Despite a sizable body of research pertaining to honey bee nutrition, relatively little is known about the effects of genetic variation on nutritional response. Advances in molecular biology and genetics have accelerated the study of nutrients at the molecular level and inherited traits at the DNA level. This research has lead to investigation of the roles of nutrients in gene and protein expression known as nutrigenomics, and concepts related to genetic variation and dietary response, known as nutrigenetics. Nutrigenomics/nutrigenetics could provide a framework for breeding improved nutrient efficiency as well as identification of genotype-dependent foods or supplements that promote health. In this study, we investigated the influence of genetic variation on responses to natural and artificial diets in Varroa-resistant Pol-line and Russian honey bee stocks. Bioassays comprising newly emerged workers from six colonies per stock were used to feed pollen and spirulina (blue-green microalgae) diets. Diet type had the strongest effect on sugar intake, body weight, abdomen lipids, and vitellogenin (vg) mRNA expression. Spirulina consumption was approximately half that of pollen, which led to higher head weights, equivalent thorax weights and vg levels, and marginally reduced abdomen lipids. Bee stock and colony had a significant impact on nutritional response. Despite equivalent diet intakes, Pol-line accumulated higher levels of abdomen lipids and consumed less sugar overall than Russian stock. Further, pollen-fed bees sourced from Pol-line colonies had significantly higher vg levels. Genotype-dependent responses to nutrition have potential applications in honey bee breeding efforts as well as tailored approaches to diet and health.

Technical Abstract: We tested the influence of genetic variation on responses to natural and artificial diets in Varroa-resistant Pol-line and Russian honey bee stocks. Newly emerged workers from six colonies per stock were fed pollen, spirulina (blue-green microalgae), and sucrose-only diets in 144 total cages. Diet type had a strong effect on sugar intake, body weight, fat body lipid content, and vitellogenin (vg) expression. Spirulina consumption was approximately half that of pollen, but led to higher head weights, equivalent thorax weights and vg levels, and marginally reduced fat body lipids. Bee stock and colony had a significant impact on nutritional response. Despite equivalent diet intakes, Pol-line bees accumulated higher lipid levels and consumed less sugar overall than Russian bees. Furthermore, pollen-fed bees sourced from Pol-line colonies had significantly higher vg levels. These differences in nutrient and energy allocation may reflect life history-related physiological tradeoffs. Our results suggest that genotype-dependent nutritional responses are present in honey bees, with promising implications for breeding efforts and tailored approaches to diet and health in a changing global climate.