DOI: 10.5061/dryad.k98sf7mkv
title: Reducing honey bee winter mortality with molybdenum supplementation: field evidence across Europe

description: Nutrition is key to improving honey bees' resilience to environmental
 stress factors that threaten their health. Yet, little is known about the
 micronutritional needs of colonies, in particular about molybdenum, an
 essential trace element in biology. This study focuses on a coordination
 complex based on molybdenum, Mo(+V), which was assessed for compatibility
 with standard beekeeping practices. It was found to be non-toxic for bees,
 stable, and easy to use. Importantly, it does not leave any residues in
 the honey produced. This study investigated how supplementation with a few
 milligrams of this complex can improve hive performance in early spring
 and reduce winter mortality. Over a two-year field campaign, 283 beehives
 spread over 6 apiaries located in Spain, Greece, and France were involved:
 142 beehives supplemented with the molybdenum-based compound and 141
 beehives as a control group. Supplementation resulted in a significant
 reduction in winter colony losses, averaging a 44% decrease, ranging
 between 27% and 75% in the different apiaries. The risk of death was twice
 lower in the Na-Mo2O4-EDTA group compared to the control group (risk
 ratio: 0.51). The impact on bee populations and honey production was also
 evaluated. A significant increase in honey reserves within the brood area
 of 107% was observed in the Greek apiary, whereas no comparable effect was
 detected in Spain, suggesting that local environmental conditions or
 management practices may influence this parameter. This study highlights
 the importance of molybdenum in the management of honey bees as an
 efficient tool to reduce the winter mortality of the colonies. The data
 set provided on Dryad includes all raw data concerning the field test in
 France, Spain, and Greece. 
description: # Data from: Reducing honey bee winter mortality with molybdenum
 supplementation: Field evidence across Europe --- This repository contains
 the data used to conduct the descriptive and statistical analyses and
 create the figures referenced in the paper of the same name. Dataset DOI:
 10.5061/dryad.k98sf7mkv --- ## Description of the data and files structure
 #### 1. `Winter_mortality.csv` **Description:** This file contains
 experimental data used for the winter mortality analysis. Data were
 collected in Spain (winters 2023 and 2024) and in France (winter 2024).
 **Variables and description:** | **Variable** | **Description** | |
 ------------ |
 ----------------------------------------------------------------- | |
 `Experiment` | Unique identifier for the experiment | | `Treatment` | Name
 of the diet | | `Mortality` | Binary variable indicating whether the
 colony died (1) or not (0) | #### 2. `Spain_2023.csv` **Description:**
 This file contains experimental data on the impact of the complex
 Na-Mo2O4-EDTA under field conditions. Data were collected in Spain
 (Trujillo, Extremadura) in colonies of *A. mellifera iberiensis* housed in
 Layens-type hives. The study duration was 265 days, from the beginning of
 November 2023 (M0) to the end of July 2024. "NA" is explained by
 the death of hives during the experiment or the impossibility of
 collecting the data (e.g., not enough bees collected in the field for
 biomarker analysis) **Variables and description:** | **Variable** |
 **Description** | | ------------ |
 ------------------------------------------------------------------------------------------------ | | `Apiary` | Unique identifier for the Apiary | | `Hive` | Unique identifier for the hive | | `Hive_ID` | Identifier for the hive nested in the Apiary | | `Treatment` | Name of the diet | | `Assessment` | Date of assessment, 0 = Day 0, 1 = Day 120, 2 = Day 265 | | `Honey` | Honey surface (cm^2^) | | `Bees` | Number of honey bees | | `TAC` | Total antioxidant capacity expressed as Trolox Equivalent Antioxidant Capacity (TEAC, µM Trolox) | | `ALP` | Alkaline phosphatase activity expressed as units per milliliter (U/mL) | #### 3. `Greece_2022.csv` **Description:** This file contains experimental data on the impact of the complex Na-Mo2O4-EDTA under field conditions. Data were collected in Greece (*Nea Moudania*) in colonies of *A. mellifera macedonica* in Langstroth nucleus hives. The experiment started mid-May 2022 and lasted 56 days. Dead bees were collected and counted in each trap every 4 days. On Day 56, the cumulated number of dead bees was summarized to one count. **Variables and description:** | **Variable** | **Description** | | ------------- | ----------------------------------------------- | | `Hive` | Unique identifier for the hive | | `Treatment` | Name of the diet | | `HoneyD0` | Honey surface (cm^2^) at Day 0 of the experiment | | `HoneyD56` | Honey surface (cm^2^) at Day 56 of the experiment | | `BeesD0` | Number of bees at Day 0 of the experiment | | `BeesD56` | Number of bees at Day 56 of the experiment | | `Morta_cumul` | Cumulated number of dead bees | --- ## Requirements All analyses were performed in the R version 4.5.1 [R Core Team (2025). *R: A Language and Environment for Statistical Computing*. R Foundation for Statistical Computing, Vienna, Austria. [https://www.R-project.org/](https://www.R-project.org/)] * [R](https://www.r-project.org/) * [RStudio](https://posit.co/downloads/) ## Access information Other publicly accessible locations of the data: * None Data was derived from the following sources: * No additional sources; data were collected by the study authors