Mild thermal stress does not negatively affect immune gene expression in the bumblebee Bombus terrestris

Abstract

Body temperature changes can modify an insect's ability to fight infections by altering its immune activity. This work evaluated the impact of mild cold and heat thermal stress on the expression of different immune and heat shock genes in the species Bombus terrestris . Additionally, a thermal treatment was repeated under starvation to analyze a possible compromise of immune gene expression in favor of a thermal stress response when energetic resources are limited. Results pointed to a role of Hsc70 and Aha1 genes in tolerance to moderately high temperatures. Expression of the immune genes was not negatively affected by the cold or the heat treatments, and the receptor gene BGRP1 was upregulated with cold, possibly indicating an increase in the cellular immune activity. Under starvation, the effect of the heat and the cold treatments caused a higher upregulation in all genes analyzed, suggesting a synergistic effect of starvation and thermal stress on the activation of heat shock and immune gene expression.bumblebee / temperature variation / heat shock genes / immunity / RT-qPCR Electronic supplementary material The online version of this article (

Thermal niches of specialized gut symbionts: the case of social bees

“…However, a recent study found that immune responses were not downregulated in bumblebees reared at 38°C [48]. Furthermore, we lack evidence that bumblebees can discriminate between their own symbiont strains and those from other Bombus, immunologically or otherwise.…”

“…Each container was provided with 10 ml of sterile 50% sugar syrup and 500 mg of sterile pollen dough (gamma-irradiated honeybee pollen mixed with sterile 50% sugar syrup). Microcolonies were reared in one of two incubators (Percival Scientific, model I36NL) set at either 29°C, representing a typical bumblebee rearing temperature [32,[46][47][48], or at 35°C, a temperature typical of A. mellifera hives [26]. The pollen lump was replaced on the third day of rearing.…”

Variance in heat tolerance in bumble bees correlates with species geographic range and is associated with several environmental and biological factors

“…( 2022 ) applied thermal tolerance data from other studies and noted a relationship between heat tolerance and several climatic variables in five North American bumble bee species. Differential heat tolerance in bumble bees may be conferred through differences in molecular heat shock response (Blasco‐Lavilla et al., 2021 ; Kuo et al., 2023 ; Pimsler et al., 2020 ), interspecific differences in heat shunting by means of counter‐current exchange between the thorax and abdomen (cf. Heinrich, 1976 ; Heinrich & Vogt, 1993 ), or through other physiological adaptations such as shifting metabolism or potential for evaporative cooling (Johnson et al., 2023 ).…”

Genotypic‐specific heat shock response of vector susceptibility to Schistosoma mansoni

“…Thermal stress has a large impact on organismal physiology, which can scale up into devastating ecosystem level effects such as the bleaching of coral reefs (Donovan et al, 2021) or the increase in infectious disease (Hector et al, 2021; Indhumathi & Sathesh Kumar, 2021). Temperature can directly alter the immune response of organisms in both positive and negative ways (Blasco‐Lavilla et al, 2021; Murdock et al, 2012; Paaijmans et al, 2010), and thus, even transient changes in temperature due to heat waves or unusual extreme weather events could alter disease dynamics and put humans, other animals, and plants at risk. Invertebrate vector hosts and their pathogens could be greatly affected by temperature elevation because temperature has a large effect on their physiological processes including immune defense pathways and also the pathogen replication rate (e.g., Dittmar et al, 2014; Franke et al, 2017; Huey & Kingsolver, 1989; Kirk et al, 2018; Seppälä & Jokela, 2011).…”