Honeybees, Bumblebees and Leaf-cutter Bees Vary in the Effect of a Simulated Pathogen Challenge on Individual Thermoregulation

Bees regulate their individual body temperatures by non-flight thermogenesis (NFT). The effects of a pathogen challenge on thermoregulation in bees generally is unknown, although honeybees have displayed opposing responses between two studies. To establish whether bees in general experience disruption of thermoregulation under pathogen challenge, we investigated a representative species of each of three major bee social backgrounds (honeybees, Apis mellifera ; bumblebees, Bombus impatiens ; and solitary bees, Megachile rotundata ) and measured the body surface temperatures of individual bees as they recovered from cold torpor by NFT after injection with lipopolysaccharide (LPS) solution, which simulated a pathogen challenge. We found that LPS injection affected rewarming in the annually eusocial B. impatiens , but not A. mellifera or the solitary M. rotundata . Specifically, the pathogen challenge increased post-recovery body temperatures by 2 o C in B. impatiens individuals. Our findings indicate that immune responses by individual bees can interfere with thermoregulation, but this effect is not consistent among major bee species.