Effects of Heat Stress on Mating Behavior and Colony Development in Bombus terrestris (Hymenoptera: Apidae)

Abstract

Climate change is related to an increase in the frequency and intensity of extreme events such as heatwaves. In insect pollinators, heat exposure is associated with direct physiological perturbations, and in several species, could lead to a decrease of fitness related to a decrease in fertility. Here we developed a new experimental protocol in controlled conditions to assess if the exposure to high temperatures could modify the attractiveness and fertility of Bombus terrestris males. Our results show that virgin queens of B. terrestris do not have preferences between the pheromonal secretions of heat-exposed and control males. Moreover, mating with a heat-exposed male has no impact on the copulation behavior and the development of the nest (brood composition). We advise to extend trials to cover a range of wild and heat-sensitive species on multiple generations to better understand the impact of heat waves on the bumblebee communities.

Protecting pollinators and our food supply: understanding and managing threats to pollinator health

“…Heatwaves in particular may induce physiological disturbances and reduce fertility. To examine heatwave effects on the reproductive capacity of a pollinator, Przybyla and colleagues examined the effects of a static and constant exposure of 40 °C, until heat stupor is reached, on males of the bumble bee species Bombus terrestris (Przybyla et al 2021). Heat stressed B. terrestris males exhibited resiliency as they did not experience a reduction in pheromone quality or copulatory behavior, and the heat exposure did not adversely affect nest development for queens mated with these males.…”

Proteomic differences in seminal fluid of social insects whose sperm differ in heat tolerance

“…To date, several risk factors have been identified that are contributing to the global decline of bumblebees, including changes in microbiota, diet, temperature and pesticide exposure [62][63][64][65]. However, many of these studies have focused on B. terrestris, a commercially available and invasive species [31] whose fitness seems to be only marginally affected by thermal stress [45,66]. The consequences of such stress could be far more dramatic in a sensitive species such as B. magnus.…”