Browsing by Author "Borba, Renata S."

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    Propolis counteracts some threats to honey bee health
    (MDPI, 2017) Simone-Finstrom, Michael; Borba, Renata S.; Wilson, Michael; Spivak, Marla
    Honey bees (Apis mellifera) are constantly dealing with threats from pathogens, pests, pesticides and poor nutrition. It is critically important to understand how honey bees’ natural immune responses (individual immunity) and collective behavioral defenses (social immunity) can improve bee health and productivity. One form of social immunity in honey bee colonies is the collection of antimicrobial plant resins and their use in the nest architecture as propolis. We review research on the constitutive benefits of propolis on the honey bee immune system, and its known therapeutic, colony-level effects against the pathogens Paenibacillus larvae and Ascosphaera apis. We also review the limited research on the effects of propolis against other pathogens, parasites and pests (Nosema, viruses, Varroa destructor, and hive beetles) and how propolis may enhance bee products such as royal jelly and honey. Although propolis may be a source of pesticide contamination, it also has the potential to be a detoxifying agent or primer of detoxification pathways, as well as increasing bee longevity via antioxidant-related pathways. Throughout this paper, we discuss opportunities for future research goals and present ways in which the beekeeping community can promote propolis use in standard colonies, as one way to improve and maintain colony health and resiliency.
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    Propolis envelope in Apis mellifera colonies supports honey bees against the pathogen, Paenibacillus larvae
    (Nature Publishing Group, 2017) Borba, Renata S.; Spivak, Marla
    Honey bees have immune defenses both as individuals and as a colony (e.g., individual and social immunity). One form of honey bee social immunity is the collection of antimicrobial plant resins and the deposition of the resins as a propolis envelope within the nest. In this study, we tested the efects of the propolis envelope as a natural defense against Paenibacillus larvae, the causative agent of American foulbrood (AFB) disease. Using colonies with and without a propolis envelope, we quantifed: 1) the antimicrobial activity of larval food fed to 1–2day old larvae; and 2) clinical signs of AFB. Our results show that the antimicrobial activity of larval food was signifcantly higher when challenged colonies had a propolis envelope compared to colonies without the envelope. In addition, colonies with a propolis envelope had signifcantly reduced levels of AFB clinical signs two months following challenge. Our results indicate that the propolis envelope serves as an antimicrobial layer around the colony that helps protect the brood from bacterial pathogen infection, resulting in a lower colony-level infection load.
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    Seasonal benefits of a natural propolis envelope to honey bee immunity and colony health
    (Company of Biologists, 2015) Borba, Renata S.; Klyczek, Karen K.; Mogen, Kim L.; Spivak, Marla
    Honey bees, as social insects, rely on collective behavioral defenses that produce a colony-level immune phenotype, or social immunity, which in turn impacts the immune response of individuals. One behavioral defense is the collection and deposition of antimicrobial plant resins, or propolis, in the nest. We tested the effect of a naturally constructed propolis envelope within standard beekeeping equipment on the pathogen and parasite load of large field colonies, and on immune system activity, virus and storage protein levels of individual bees over the course of a year. The main effect of the propolis envelope was a decreased and more uniform baseline expression of immune genes in bees during summer and autumn months each year, compared with the immune activity in bees with no propolis envelope in the colony. The most important function of the propolis envelope may be to modulate costly immune system activity. As no differences were found in levels of bacteria, pathogens and parasites between the treatment groups, the propolis envelope may act directly on the immune system, reducing the bees’ need to activate the physiologically costly production of humoral immune responses. Colonies with a natural propolis envelope had increased colony strength and vitellogenin levels after surviving the winter in one of the two years of the study, despite the fact that the biological activity of the propolis diminished over the winter. A natural propolis envelope acts as an important antimicrobial layer enshrouding the colony, benefiting individual immunity and ultimately colony health.