ORIGINAL PAPER The interplay between genetic and environmental effects on colony insularity in the clonal invasive little fire ant Wasmannia auropunctata Merav Vonshak & Tamar Dayan & Julien Foucaud & Arnaud Estoup & Abraham Hefetz Received: 26 January 2009 / Revised: 5 May 2009 / Accepted: 5 May 2009 / Published online: 23 May 2009 # Springer-Verlag 2009 Abstract The little fire ant, Wasmannia auropunctata, constitutes one clonal supercolony throughout Israel, provid- ing an opportunity to examine the effects of genotype versus environment on nestmate recognition. Intraspecific encoun- ters among field-collected or among laboratory-maintained colonies were nonaggressive, but encounters between freshly collected and laboratory-maintained colonies were highly aggressive. Analyses of cuticular hydrocarbons revealed that freshly field-collected colonies had distinguishable profiles. Moreover, freshly collected colonies had profiles disparate from those of the same colonies after 4 months in the laboratory. These results indicate a strong interplay between genetic-based and environmentally based effects on the recognition cues. We propose that in the field the ants’ diet breadth is broad and consequently the incorporation of diet- borne substances is insufficient to mask the genetically determined cues. In the laboratory, however, the restricted diet promoted the incorporation of alien hydrocarbons at high levels, thus altering the genetically based cues to the point of alienation. These results shed a new light on the mechanisms by which environmental cues may affect label and/or template formation in ants. Keywords Invasive species . Wasmannia auropunctata . Cuticular hydrocarbons . Nestmate recognition Introduction Discriminating between nestmates and nonnestmates is crucial for the functioning of social insect colonies; nestmate recognition allows them to reject alien conspe- cifics and thus prevent them from taking advantage of the colony’ s wealth (Hölldobler and Wilson 1990). Cuticular hydrocarbons (CHC) were shown directly or indirectly to serve as nestmate recognition cues in several ant species (reviewed by Hefetz 2007). The composition of ant CHCs is generally dynamic (Lahav et al. 2001) and is affected both by the genetic makeup of the colony and environmen- tal influences such as diet (Liang and Silverman 2000; Richard et al. 2004; Silverman and Liang 2001), habitat (Heinze et al. 1996; Nielsen et al. 1999), or time of year (Nielsen et al. 1999). Novel hydrocarbons are rapidly integrated into the recognition system by means of continuous exchanges between nestmates (Lenoir et al. 2001; Soroker et al. 1995). The relative contribution of environmental factors vs. innate factors on nestmate recognition can vary according to species. Zinck et al. (2008) suggested that both genetic and environmental cues are involved in nestmate recogni- tion in Ectatomma tuberculatum. In Temnothorax long- ispinosus, however, genetic relatedness was found to be a more important contributor to aggressive behavior than geographic distances (Stuart and Herbers 2000). In contrast, Chen and Nonacs (2000) claimed that nestmate recognition Behav Ecol Sociobiol (2009) 63:1667–1677 DOI 10.1007/s00265-009-0775-9 Communicated by J. Heinze Electronic supplementary material The online version of this article (doi:10.1007/s00265-009-0775-9) contains supplementary material, which is available to authorized users. M. Vonshak (*) : T. Dayan : A. Hefetz Department of Zoology, Life Sciences Faculty, Tel Aviv University, Tel Aviv 69978, Israel e-mail: meravwei@post.tau.ac.il J. Foucaud : A. Estoup UMR Centre de Biologie et de Gestion des Populations (INRA/ IRD/Cirad/Montpellier SupAgro), INRA, Campus international de Baillarguet, CS 30016, 34988 Montferrier-sur-Lez, France