Page Banner

United States Department of Agriculture

Agricultural Research Service

Research Project: Understanding Honey Bee Microbiota to Improve Bee Nutrition and Colony Health

Location: Honey Bee Research

Project Number: 2022-21000-017-00
Project Type: Appropriated

Start Date: Feb 07, 2014
End Date: Feb 06, 2019

Objective:
Increasing evidence points to a core honey bee gut microbiota, however the distribution and function of peripheral bacterial and fungal communities in honeybees and their food stores are relatively unknown. Our work will focus on beebread to define the contribution of unknown and seemingly benign microbes to colony health and nutrition. Beebread provides the bulk of proteins, vitamins and lipids that bees consume. We will determine the microbial succession in beebread to understand the distribution of these beebread-associated microbial communities and whether these communities contribute to the nutritive value of pollen, its digestion and storage, and the potential for disease transmission and amplification. We will examine factors associated with beekeeping and agricultural practices that may affect the microbial balance of the honey bee and its stored food, including colony origin, supplemental feeding, nectar source, pollen type, and exposure to biocides. These data will inform our perspective on how microbial communities contribute to colony health. OBJECTIVES Our overall goal is to provide beekeepers and growers with practical advice for the maintenance of transitory commercial honey bee populations. Using a combination of laboratory and field approaches we will develop an understanding of the diversity, abundance, persistence and functional capacities of the microorganisms that occur in bees, stored food, the hive, and the general pollination environment. This information will be applied to the management of disease, nutrition, overwintering and biocides in the context of commercial beekeeping. Objective 1: Determine the core fungal microbiota in bee bread and determine relationships with bacterial communities. Sub-objective 1A: Enumerate, identify, and characterize the core fungal and bacterial microbiota of beebread. Objective 2: Characterize microbial succession in bee bread, including core and non-core microbes and their persistence during overwinter pollen storage. Sub-objective 2A: Identify the microbial communities involved in the conversion of corbicular pollen to beebread. Sub-objective 2B: Determine the impact of overwintering on the microbes in beebread. Objective 3: Identify factors affecting a colony's microbial diversity, including plant monocultures, exposure to biocides, and supplemental feeding. Sub-objective 3A: Determine the effect of supplemental feeding on microbial communities. Sub-objective 3B: Determine the effect of monoculture nectar and pollen source on microbial communities. Sub-objective 3C: Determine the effect of fungicides on microbes during beebread formation.

Approach:
Sub-objective 1A: Determine whether beebread contains a core microbial community. Beebread will be sampled from multiple colonies, apiaries, and commercial operations across a variety of locations and seasons. rRNA will be used to characterize the active microbiota of beebread. Fungal and bacterial groups identified at different levels of taxonomic certainty will be examined for significant co-occurrence using a variety of available metrics (including options for degenerate matrices) and a null hypothesis of random community assembly. Sub-objective 2A: Determine whether the active microbial (bacterial and fungal) community remains constant as corbicular pollen becomes beebread and as beebread ages. We will detail the active fungal and bacterial communities in multiple colonies, controlling for the source of corbicular pollen and season. Multiple replicates of beebread at 0.5, 1, 3, 7, 14, and 30 days of age will be sampled and processed for microbial composition. Dependent upon the predictability of a "core" functional set of successional genes in beebread, we will develop metagenomic profiling methods for a more efficient characterization of microbial function. Sub-objective 2B: Determine whether the microbial communities of overwintered beebread sampled from old wax comb differ from those of new wax comb. Beebread will be collected in RNA later from both old and new wax comb from commercial beekeeping operations. RNA extracted from beebread will be subject to 454 amplicon sequencing and compared according to overwintering status and comb age. If differences in the microbial communities are discovered, we will determine the nutrients, preservatives and metabolites associated with these changes. Sub-objective 3A: Determine whether supplemental feed affects the active honey bee gut microbial community. Bees will be fed commonly used brewer's yeast/soy/sucrose-based nutritional supplements containing thymol alone, citric acid alone, thymol and citric acid, honey bee healthy, no additives, and fresh beebread/honey as a control. RNA will be extracted from these pooled samples and community composition of the gut will be assessed using qRT-PCR targeted to the core gut bacteria. Sub-objective 3B: Determine whether the active microbial communities in beebread differ by pollination environment. We will sample both corbicular pollen and beebread microbial communities of colonies actively pollinating two distantly located monocultures and two distantly located plant polycultures. Samples will be subject to qRT-PCR targeting specific genera, and also pooled by colony and subject to 454 amplicon sequencing for comparative purposes. If species-specific qRT-PCR primers prove overly time consuming or inefficient, we will rely on the sequencing of major functional COGs. Sub-objective 3C: Determine whether the microbes and nutrition in bee bread are affected by fungicide. Endura fungicide will be applied at field concentrations to a Brassica mix grown in greenhouses. Bees will be allowed to forage on fungicide sprayed and non-fungicide controls. Beebread will be examined for microbial communities, fungicide concentrations and nutritional analysis.

Last Modified: 12/20/2014
Footer Content Back to Top of Page