The heat is on: reduced detection of floral scents after heat waves in bumblebees

Global climate change disrupts key ecological processes and biotic interactions. The recent increase in heat wave frequency and severity prompts the evaluation of physiological processes that ensure the maintenance of vital ecosystem services such as pollination. We use experimental heat waves to determine how high temperatures affect the bumblebees’ ability to detect floral scents. Heat waves induced strong reductions in antennal responses to floral scents in both tested bumblebee species (Bombus terrestris and Bombus pascuorum). These reductions were generally stronger in workers than in males. Bumblebees showed no consistent pattern of recovery 24 hours after heat events. Our results suggest that the projected increased frequency and severity of heat waves may jeopardize bumblebee-mediated pollination services by disrupting the chemical communication between plants and pollinators. The reduced chemosensitivity can decrease the bumblebees’ abilities to locate food sources and lead to declines in colonies and populations.

Methods
The collected data are electroantennography (EAG) recordings. The antennal signal to stimulus was 10 times pre-amplified, converted to a digital signal using a DC amplifier interface (IDAC-2, Syntech) and recorded with GC-EAD software (GC-EAD 2014, version 1.2.5, Syntech). See method section of the manuscript 'Physiological experiments – electroantennography' for more detailed description.

The statistical analyses were conducted in R Studio (R version 4.3.2 (2023-10-31) -- "Eye Holes" Copyright (C) 2023 The R Foundation for Statistical Computing Platform. 
The following packages were used: library(MASS), library(car), library(emmeans),library (glmmTMB), for the plots library(ggplot2) for the plots library(ggplot2).