Data from: Resident viruses, but not honeybee-associated viruses, impair solitary bee fitness in the field
Abstract
Viruses can impact individual host fitness and host population dynamics, especially following viral host shifts. The decline of bee populations over the last decades may be linked to viruses spilling over from honeybees. However, evidence for the impact of spillover or resident viruses on solitary bee fitness remains scarce. Here, by assessing solitary bee (Osmia cornuta) foraging, offspring sex ratio, survival, and body mass across seven locations in northern Switzerland, we show that resident viruses – but not honeybee-associated viruses –impact tokens of fitness in the field. Viral loads of Osmia-resident Ganda bee virus (GABV) and Scaldis River bee virus (SRBV), honeybee-associated viruses (black queen cell virus (BQCV) and deformed wing virus B (DWV-B) were quantified in foraging females. Prevalence and loads of GABV and SRBV were higher than BQCV and DWV-B. Further, females with high SRBV or GABV loads had reduced offspring survival or lower male offspring body mass, respectively, while honeybee-associated viruses had no impact on tokens of O. cornuta fitness. We demonstrate that viruses can negatively affect solitary bee fitness, but the degree of impact seems to vary with viral type. This calls for further research to unravel the dynamics of multi-host pathogens in pollinator communities.
https://doi.org/10.5061/dryad.m0cfxppfg
Description of the data and file structure
All tagged females that could be re-captured (n = 48) were screened individually for four viruses: resident Ganda bee virus – GABV and Scaldis River bee virus – SRBV, and viruses originally detected in Apis mellifera (deformed wing virus B – DWV-B and black queen cell virus – BQCV). Additionally, eight females from cocoons that were not released to the field but stemming from the same batch of cocoons (i.e., generation F0) as the released bees were frozen in their cocoons, then extracted under sterile conditions and screened for the same four viruses to serve as controls. See method section of the article for more details on the methods.
Files and variables
File: Data.zip
Description:
The data.zip contains three data files:
- hatching_virus_new_loads.csv: data of the reproductive success and virus load of the tagged Osmia cornuta females that were nesting in the trapnests at the orchard sites
- forag_trips_summarised_new_virus_loads.csv: data on the foraging trip duration of the tagged females
- virus_all_new.csv: virus load data of the foraging females as well as of the cocoons from the same batch, that were not released to the field but directly frozen instead
Variables in hatching_virus_new_loads.csv:
- ORCHARD = ID of the orchard where the trapnest was placed
- TRAPNEST = ID of the trapnest
- BEE_ID = ID on the tag of the foraging female
- CAVITY_ID = ID of the nesting cavity (of the trapnest)
- Nest_diameter = Diameter of the nesting cavity in mm
- nr.alive = number of offspring that was hatching in this cavity
- nr.dead = number of offspring that was not hatching in this cavity
- nr.females = number of female offspring in this cavity
- nr.males = number of male offspring in this cavity
- mean_mass_mg_f = mean body mass of all female offspring of this cavity
- mean_mass_mg_m = mean body mass of all male offspring of this cavity
- DWV_B_GE_per_ug_total_RNA = number of Genome equivalents (viral copies) of DWVB (deformed wing virus) per ug of total RNA of the mother bee nesting in this cavity
- DWVB_copies_per_bee = number of Genome equivalents (viral copies) of DWVB (deformed wing virus) of the mother bee nesting in this cavity
- BQCV_GE_per_ug_total_RNA = number of Genome equivalents (viral copies) of BQCV (black queen cell virus) per ug of total RNA of the mother bee nesting in this cavity
- BQCV_copies_per_bee = number of Genome equivalents (viral copies) of BQCV (black queen cell virus) of the mother bee nesting in this cavity
- GABV_GE_per_ug_total_RNA = number of Genome equivalents (viral copies) of Ganda bee virus (GABV) per ug of total RNA of the mother bee nesting in this cavity
- GABV_copies_per_bee = number of Genome equivalents (viral copies) of Ganda bee virus (GABV) of the mother bee nesting in this cavity
- SRBV_GE_per_ug_total_RNA = number of genome equivalents (viral copies) of Scaldis bee virus (SRBV) per ug of total RNA of the mother bee nesting in this cavity
- SRBV_copies_per_bee = number of genome equivalents (viral copies) of Scaldis bee virus (SRBV) of the mother bee nesting in this cavity
- SNH_PLAND_500 = percentage of landscape covered by semi-natural habitat (SNH, extensively managed meadows and pastures, flower strips, hedgerows, forest) in a 500m radius around the trap nest
- Bee_mass_mg = Mass of the mother Osmia cornuta in mg
- Mean_nr_HB = mean number of honeybees counted along the 4 transects per site
additional variables (to those already described above) in forag_trips_summarised_new_virus_loads.csv:
- DURATION.min.mean = mean foraging trip duration of all foraging trips done by this bee in minutes
additional variables (to those already described above) in virus_all_new.csv:
- Lab_ID = unique ID of the samples that was given in the lab
- ...Average_Cq = the average Cq-value of the sample of the respective virus
- ...GE_per_ug_total_RNA.log = log-transformed number of genome equivalents of the respective virus
- Sample_type = either "nesting_females" (females that were freely foraging and nesting in the provided trapnests or "control cocoons" (cocoons from the same batch as the field females, but they were directly frozen, not hatching in the field)
The empty cells represent missing values.
Code/software
The files include the scripts to run the statistical models and plot the relationships based on the provided data sets (hatching_virus_new_loads.csv, forag_trips_summarised_new_virus_loads.csv and virus_all_new.csv) in the software R version 4.2.1.
Scripts for running the statistical models (incl. backwards model selection):
- clean_models_sur_sexr_bm_v3: Script for running the models for the response variables survival of offspring, sex ratio of offspring and body mass of male and body mass of female offspring
- clean_models_foraging_v3: Script for running the models for the response variable mean foraging trip duration of foraging Osmia cornuta females
Scripts for plotting the relationships:
- plot_bayes_survival_v3: script for creating the plots of the relationships offspring survival ~ Scaldis river bee virus load in mothers
- plot_bayes_sex-ratio_v3: script for creating the plot of the relationship offspring sex ratio ~ body mass of mothers
- plot_bayes_bm_males_v3: script for creating the plot of the relationship body mass of male offspring ~ Ganda bee virus load in mothers
- plot_bayes_bm_fem_v3: script for creating the plots of the relationships body mass of female offspring ~ Ganda bee virus load in mothers and body mass of female offspring ~ body mass of mothers
- boxplot_virus_load_new: script for creating the boxplot of virus load per virus
Solitary bee Osmia cornuta trap nests were placed in seven apple orchards in northern Switzerland and supplied with O. cornuta cocoons at the time when the apple started blooming. To track individual O. cornuta female nesting activity, foraging performance and different aspects of reproductive success (survival, sex ratio, and body mass of offspring), we individually tagged females, videoed their foraging activity at their individual nests and used machine learning-based software for automated analysis of the videos ("Bee Tracker", Knauer et al. 2022, doi:10.1002/ece3.8575). After video recording at all sites was completed (12 days after the confirmed start of nesting), we collected all tagged females at night when the females were resting in their nests and freeze-killed the bees for later analysis of viruses. After overwintering, each offspring (cocoon) of an identified nest from a tagged female was transferred into a separate labelled 2-mL Eppendorf® tube with a small hole to allow air exchange. We recorded whether or not the offspring successfully hatched (survival, i.e., alive vs. dead), determined its sex morphologically (i.e., female or male), and measured its body mass (in mg). From the videos, we further extracted the foraging trip duration of the tagged females (in min).