DOI: 10.5061/dryad.jh9w0vth8
title: Synergistic negative effects between a fungicide and high temperatures on homing behaviours in honey bees

description: Interactions between environmental stressors may contribute to ongoing
 pollinator declines, but have not been extensively studied. Here, we
 examined the interaction between the agricultural fungicide Pristine®
 (active ingredients: 25.2% boscalid, 12.8% pyraclostrobin) and high
 temperatures on critical honey bee behaviours. We have previously shown
 that consumption of field-realistic levels of this fungicide shortens
 worker lifespan in the field and impairs associative learning performance
 in a laboratory-based assay. We hypothesized that Pristine® would also
 impair homing and foraging behaviours in the field, and that an
 interaction with hot weather would exacerbate this effect. Both
 field-relevant Pristine® exposure and higher air temperatures reduced the
 probability of successful return on their own. Together, the two factors
 synergistically reduced the probability of return and increased the time
 required for bees to return to the hive. Pristine® did not affect the
 masses of pollen or volumes of nectar or water brought back to the hive by
 foragers, and it did not affect the ratio of forager types in a colony.
 However, Pristine®-fed bees brought more concentrated nectar back to the
 hive. As both agrochemical usage and heat waves increase, additive and
 synergistic negative effects may pose major threats to pollinators and
 sustainable agriculture. 
description: Microsoft Excel for .csv files; R for .R files
description: # Synergistic negative effects between a fungicide and high temperatures
 on homing behaviours in honey bees Access this dataset on Dryad:
 These experiments measured
 the effects of the agricultural fungicide Pristine on honey bee navigation
 and foraging behaviours. In the navigation experiment, bees were captured
 from their individual colonies (which had either been exposed to the
 fungicide or had served as controls), marked with either a queen tag or an
 RFID tag, and then released 1 km from their hive. Human observers or RFID
 readers recorded the time each marked individual returned to the hive. In
 the foraging experiments, returning foragers from the same colonies were
 captured at hive entrances. Their foraging success was measured by
 determining the volume and sugar concentration of their crop contents and
 the mass of their corbicular pollen loads. ## Description of data and file
 structure The navigation data details whether individual bees (either
 exposed to the fungicide Pristine or controls) returned to their hives
 after being released one km away (either 'yes' or
 'no', and also gives the time (in minutes) it took successful
 bees to return. There were three separate runs of the experiment, in
 October 2021, August 2022, and October 2022. Weather data were taken from
 the Phoenix-Mesa Gateway Airport weather station and included the air
 temperature (degrees Fahrenheit), cloud cover (categorical approximation),
 wind direction (categorical approximation), and wind speed (miles per
 hour). A separate set of bees were used for the foraging experiment,
 although these bees came from the same colonies as in the navigation
 experiment. These data consist of the mass of corbicular pollen (mg), crop
 volume (uL), and crop sugar concentration (%) brought back to the hive by
 returning foragers. Each bee is classed as either a pollen, nectar, or
 water forager depending on the resources it carried. Run 1 (R1) occurred
 in August 2022, while run 2 (R2) occurred in October 2022. The temperature
 was the outside air temperature in degrees Fahrenheit at the time of
 forager collection and was taken from the same source as in the navigation
 experiment. ## Code The code comes in the form of two R scripts and was
 originally run in R version 4.2.2. The navigation code contains the models
 used to test the navigation data for statistical significance. We used
 generalized linear mixed models (lme4 package) for probability of return
 and mixed effects Cox models (coxme package) for time to return. Code for
 graphing the results (ggplot2 package) is also included. The navigation
 code contains the models used to test the foraging data for statistical
 significance. We used linear mixed models (lme4 package).