Alarm pheromones do not mediate rapid shifts in honey bee guard acceptance threshold.
Honey bee (Apis mellifera) guards discriminate nestmates from non-nestmates at the hive entrance. The acceptance threshold of guards is known to change adaptively, for example becoming less permissive when the number of intruder bees from other colonies increases. These adaptive shifts can occur within minutes. What is unknown is the mechanism behind this rapid shift. It was hypothesized that alarm pheromones released by guards may cause the adoption of a less permissive acceptance threshold. Here, we tested this hypothesis on five discriminator hives by using a behavioral assay. We used three amounts each of iso-pentyl acetate (IPA) and 2-heptanone (2H), which are the major components of the pheromones from the sting and the mandibular glands, respectively. Biologically relevant levels of chemicals were delivered to the hive entrance platform via an air pump. We found no effect of either IPA or 2H: there was no change in guard acceptance of either nestmate (on average, 91% accepted) or non-nestmate (on average, 30% accepted) under any of the pheromone treatments compared to the pentane control (98% nestmates accepted and 32% non-nestmates accepted). Therefore, we reject the hypothesis that the presence of IPA or 2H causes a rapid shift of guard acceptance threshold.
Laboratory of Apiculture & Social Insects, School of Life Sciences, University of Sussex, Falmer, Brighton, UK. M.Couvillon@Sussex.ac.uk
Margaret J
MJ
Couvillon
Sarah N
SN
Barton
Jennifer A
JA
Cohen
Onna K
OK
Fabricius
Martin H
MH
Kärcher
Lee S
LS
Cooper
Matthew J
MJ
Silk
Heikki
H
Helanterä
Francis L W
FL
Ratnieks
D000819:Animal Communication; D000818:Animals; D001516:Bees / Q000502:physiology*; D007659:Ketones / Q000378:metabolism; D000439:Pentanols / Q000378:metabolism; D010675:Pheromones / Q000502:physiology; D012919:Social Behavior; D012931:Social Environment
D007659:Ketones; D000439:Pentanols; D010675:Pheromones; C011917:2-heptanone; C005716:amyl acetate