Impacts of Diverse Natural Products on Honey Bee Viral Loads and Health

Abstract

Western honey bees (Apis mellifera), a cornerstone to crop pollination in the U.S., are faced with an onslaught of challenges from diseases caused by parasites, pathogens, and pests that affect this economically valuable pollinator. Natural products (NPs), produced by living organisms, including plants and microorganisms, can support health and combat disease in animals. NPs include both native extracts and individual compounds that can reduce disease impacts by supporting immunity or directly inhibiting pathogens, pests, and parasites. Herein, we describe the screening of NPs in laboratory cage studies for their effects on honey bee disease prevention and control. Depending on the expected activity of compounds, we measured varied responses, including viral levels, honey bee immune responses, and symbiotic bacteria loads. Of the NPs screened, several compounds demonstrated beneficial activities in honey bees by reducing levels of the critical honey bee virus deformed wing virus (DWV-A and-B), positively impacting the gut microbiome or stimulating honey bee immune responses. Investigations of the medicinal properties of NPs in honey bees will contribute to a better understanding of their potential to support honey bee immunity to fight off pests and pathogens and promote increased overall honey bee health. These investigations will also shed light on the ecological interactions between pollinators and specific floral food sources.

Seasonal patterns of beneficial phytochemical availability in honey and stored pollen from honey bee colonies in large apiaries

“…Studies have also reviewed the digestibility of pollen and its nutritional content for animals (Roulston and Cane 2000) focusing on individual plant species, their pollen structure and content. Other more recent studies have looked at the benefits of supplementing natural products in honey bee diets to narrow down products that are beneficial (Masai Biller 2015, Thorburn et al 2015, Giacomini et al 2018, Boncristiani et al 2021). Additional studies analyzed bee-collected pollen for seasonal differences in macronutrient composition, particularly protein content and amino acid and fatty acid concentrations (DeGrandi-Hoffman et al 2018, 2021), and others have described the overall chemical composition of hive-pollen following metabolomic analyses (Arathi et al 2018, Chakrabarti et al 2019).…”

“…These phytochemicals include phenolic acids, phenols, sterols, tannins, alkaloids, terpenes, flavanols, flavanones, and flavones (Adler 2000, Michalkiewicz et al 2008, Pyrzynska and Biesaga 2009, Keckes et al 2013, Chakrabarti et al 2019, Palmer-Young et al 2019). Research consensus indicates the importance of diverse floral resources to ensure that bees have access to a variety of phytochemicals (Arathi et al 2018, Chakrabarti et al 2019, Boncristiani et al 2021). However, there is not enough evidence on the availability of phytochemicals within the stored reserves in honey bee colonies.…”

Insights into the Role of Natural Products in the Control of the Honey Bee Gut Parasite (Nosema spp.)

“…For instance, algae, fungi, plants, bacteria, animal, and insect products exhibit diverse pharmacological properties and provide feasible alternative therapeutic benefits, not only for humans but also for animals. Instead of using conventional drugs to overcome honey bee pathogens scientists have increasingly turned to natural resources to minimize the harmful effects of chemical treatments on honey bees and agricultural crops [ 21 , 22 ].…”

Understanding effects of floral products on bee parasites: Mechanisms, synergism, and ecological complexity

“…Given mounting concerns about ongoing bee declines ( Potts et al, 2010 ; Rodger et al, 2021 ; Vanbergen and Initiative, 2013 ; Zattara and Aizen, 2021 ), and the recognition that parasites, in combination with other stressors, may be contributing to these declines ( Averill et al, 2021 ; Cameron et al, 2011 ; Goulson et al, 2015 ), there has been a recent surge in interest in the therapeutic and preventive potential of phytochemicals against bee disease. Much of this work has been motivated by an interest in controlling disease in commercial honey bee colonies, and includes many phytochemicals that are unlikely to be encountered by wild-foraging bees, at least not at the concentrations to which they are exposed in experimental studies (e.g., Boncristiani et al, 2021 ; Flesar et al, 2010 ; Maistrello et al, 2008 ). This research has advanced in parallel with growing interest in leveraging the antimicrobial and antifungal capacity of phytochemicals to promote human health by ‘natural’ means.…”