A queen's worker attractiveness influences her movement in polygynous colonies of the red imported fire ant (Hymenoptera : Formicidae) in response toadverse temperatures

The movement of polygynous Solenopsis invicta Buren queens from hot environ ment to a cooler environment was influenced by the queen's dominance rankin g within the colony. This study used a split nest design in which the tempe rature could be controlled independently in either of the two nest areas th at were joined by a sealable plastic tube. Before the study, three queens w ere marked and ranked by worker preference fi om a small fire ant colony an d introduced into one of these nest areas. After they were acclimatized to the nest, the colony was induced to move by changing the nest temperature. When subjected to increasing heat, the colony left the nest and moved to a cooler location. The results showed that the alpha (most preferred) queen h ad an advantage over the beta and gamma queens when exposed to hot conditio ns because the workers demonstrated a definite pattern of behavior of selec tively moving the queens from the hot nest to the cooler alternate nest. Th e behavior of the workers and the queens during the colony's movement was o bserved and time to reach safety for each queen was recorded. The workers a ppeared to have a significant control over the queen's movement. If the que ens were separated from each other and had only one choice of a route to sa fety, the least dominant (gamma) queen arrived at the new nest location fir st, because there were fewer workers to interfere with her movement. When t he queens were together, the dominant queen arrived at the alternate nest f irst; dominant queens workers interfered with the movement of the subordina tes. However, given a choice between a favorable and harsher nest, the leas t dominant queen chose equally between the two; whereas, the dominant queen had little choice, her workers chose the favorable nest. We repeated the e xperiment by subjecting the colony to cold conditions. When the nest was co oled the workers aggregated around each queen and became inactive.