No evidence for male attraction to cephalic labial gland pheromones in Bombus terrestris (Hymenoptera: Apidae)

Abstract

The ecological impact of Bombus terrestris (Linnaeus, 1758) (Hymenoptera: Apidae) following its introduction to regions outside its native range has raised significant concerns, particularly regarding the decline of native pollinators. Male B. terrestris secrete pheromones that are used in reproductive communication, and which have the potential to be used as trap attractants to control invasive populations. However, while gynes (virgin reproductive females) are known to be attracted to these pheromones, nothing is known about behavioral responses of male B. terrestris to them. Here, we investigated whether male B. terrestris exhibit attraction to pheromone extracts from conspecific males under controlled laboratory conditions. A Y-tube olfactometer was used to present B. terrestris males with a choice between a pheromone extract and a control treatment. Males were shown to respond to a positive control of lavender oil; however, they exhibited no attraction to the pheromone extracts. Several factors, such as pheromone concentration, age of individuals, or apparatus design, may have influenced these results. These findings contribute to our knowledge of bumblebee chemical communication and may inform future experimental design to assess pheromone attraction in bumblebees.