Queen substance dispersal by messenger workers in honeybee colonies

Abstract

1. Worker honeybees contacting a queen can transport the queen's inhibitory signal, queen substance, to other workers unable to contact the queen. Airborne dispersal of queen substance is at most a minor mechanism for queen substance transmission. 2. This worker transport of queen substance is an important supplement to queen substance dispersal by direct queen-worker contacts. For although colonies lose their inhibition against queen rearing within 10 h of queen loss, a queen contacts only approximately 35% of the broodnest workers in 10 h. 3. The queen facilitates queen substance dispersal by frequently standing stationary, at which times workers can thoroughly contact her, and by occasionally making a major shift in her position within the nest. 4. Queen attendance by workers is strongly age-dependent, with 3–9 days being the age range for intense contact with the queen. 5. Workers that have made extensive (>30s) queen contact appear to behave as ‘messengers’ dispersing queen substance. They walk more rapidly, antennate nestmates and receive inspections more frequently, and perform fewer labor acts in the 30 min following queen contact than do randomly chosen broodnest workers of the same age (control bees). 6. The following observations support the surface transport model over the food exchange model for queen substance transmission by workers: (1) the higher frequency of antennations with nestmates and of inspections by nestmates for messenger bees relative to control bees, (2) the close correlation (r=0.76) for messenger bees between duration of queen contact and number of inspections by nestmates, and (3) the low frequency of food donations (x=1.8) compared with nestmate antennations (x=56.4) by messenger bees in the 30 min following queen contact. 7. There are no messenger bee specialists cycling rapidly between contacts with the queen and workers. 8. Messenger bees were analyzed by gas chromatography for (E)-9-oxodec-2-enoic acid. As little as 0.1 ng (=3.3x1011 molecules) of the acid per messenger bee could have been detected, but none was found. 9. The evolution of messenger behavior by workers and the significance of the findings to understanding the timing of colony reproduction are discussed.