Nest Emigration Behavior of the Asian Needle Ant, Brachyponera (=Pachycondyla) chinensis Emery (Hymenoptera: Formicidae)

Ant colonies change nest location in response to physical disturbance, climate fluctuation, and resource availability. During the emigration process, worker recruitment is vital to ensuring that individual colony members are moved to the new nest site. Recruitment methods used during emigration differ between ant species. In a laboratory study, we investigated the recruitment behaviors of the invasive Asian needle ant, Brachyponera (=Pachycondyla) chinensis (Emery), during nest emigration. Subsets of P. chinensis worker ants were subjected to physical nest disturbance, and the recruitment methods and associated behaviors were recorded. Before recruitment to the new nest location began, B. chinensis ants organized into three distinctive groups: queen-tending, brood-tending, and scouting. Once the new nest site was identified, scout ants began physically transporting nestmates into the new harborage. Transport rates increased with time in the first 30 minutes and did not change during the 30to 55 minute interval when brood was transported. However, adult transport rate increased again after brood transport was completed and decreased after 90 minutes. These studies are the first to identify the recruitment methods, division of labor, and social organization behavior of B. chinensis during nest emigration.