Authors: Gissella M Vásquez Jules Silverman
Publish Date: 2007/10/03
Volume: 62, Issue: 4, Pages: 537-548
Abstract
In most social insect species individuals recognize and behave aggressively towards nonnestmate conspecifics to maintain colony integrity However introduced populations of the invasive Argentine ant Linepithema humile exhibit pronounced variation in intraspecific aggression denoting diversity in nestmate recognition behavior which possibly shapes their social structure and the varying levels of unicoloniality observed among these populations One approach to better understand differential aggression behaviors towards conspecifics and recognition cue perception and response in L humile is to examine variation in nestmate discrimination capability among genetically distinct colonies under different social contexts Consequently we investigated the dynamics of queen and worker recognition in southeastern US L humile queenless and queenright colonies by measuring rates of nonnestmate worker and queen adoption and intercolony genetic similarity Aggression levels between colony pairs differed and were associated with nonnestmate worker but not queen adoption Adoption of queens and workers was a function of host colony origin while colony queen number affected adoption of queens but not workers with queens more readily accepted by queenless hosts Fecundity of adopted nonnestmate queens was comparable to that of rejected nonnestmate and host colony queens suggesting that queen fecundity did not affect adoption decisions Genetic similarity between colonies ranged from 30 to 77 alleles shared with more genetically similar colonies showing lower levels of intraspecific aggression Nonnestmate queens and workers that were more genetically similar to host colony workers were more likely to be adopted We provide the first evidence for the role of L humile colony queen number on queen discrimination and suggest an effect of resident queens on worker conspecific acceptance thresholds Our findings indicate a role for genetically based cues in L humile nestmate recognition However subtle discrimination capability seems to be influenced by the social context as demonstrated by more frequent recognition errors in queenless coloniesWe thank C Schal E Vargo W Watson and three anonymous reviewers for helpful comments on the manuscript We also thank C Brownie for statistical advice and A Carper J Leonard and P Labadie for technical assistance This study was supported by the Blanton J Whitmire Endowment at North Carolina State University and the David R Nimocks fellowship G V
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