Colony disassociation following diet partitioning in a unicolonial ant

Discriminating nestmates from alien conspecifics via chemical cues is recog nized as a critical element in maintaining the integrity of insect societie s. We determined, in laboratory experiments, that nestmate recognition in a n introduced population of the Argentine ant, Linepithema humile, is modifi ed by hydrocarbons acquired from insect prey, and that workers from spatial ly isolated colony fragments, each provided with prey that possessed distin ct cuticular hydrocarbons, displayed aggressive behavior towards their form er nestmates. Isolation for 28 days or more between colony fragments fed di fferent prey was sufficient to prevent re-establishment of inter-nest commu nication for at least an additional 28 days through the introduction of a b ridge between the nests. Ants possessed intrinsic cuticular hydrocarbons pl us only those hydrocarbons from the prey they received during the isolation period. Colony fragments which were isolated for less than 28 days reunite d with workers possessing both prey hydrocarbons. Therefore, L, humile nest mate recognition may be dynamic, being in part dependent on the spatio-temp oral distribution of prey, along with physical factors permitting or restri cting access of subcolony units to those prey.