Acoustical mimicry in a predatory social parasite of ants

Department of Animal and Human Biology, University of Turin, 10123 Turin, Italy.
Journal of Experimental Biology (Impact Factor: 2.9). 12/2009; 212(Pt 24):4084-90. DOI: 10.1242/jeb.032912
Source: PubMed


Rapid, effective communication between colony members is a key attribute that enables ants to live in dominant, fiercely protected societies. Their signals, however, may be mimicked by other insects that coexist as commensals with ants or interact with them as mutualists or social parasites. We consider the role of acoustics in ant communication and its exploitation by social parasites. Social parasitism has been studied mainly in the butterfly genus Maculinea, the final instar larvae of which are host-specific parasites of Myrmica ants, preying either on ant grubs (predatory Maculinea) or being fed by trophallaxis (cuckoo Maculinea). We found similar significant differences between the stridulations of model queen and worker ant castes in both Myrmica sabuleti and Myrmica scabrinodis to that previously reported for Myrmica schencki. However, the sounds made by queens of all three Myrmica species were indistinguishable, and among workers, stridulations did not differ significantly in two of three species-pairs tested. Sounds recorded from the predatory caterpillars and pupae of Maculinea arion had similar or closer patterns to the acoustics of their host Myrmica sabuleti than those previously reported for the cuckoo Maculinea rebeli and its host Myrmica schencki, even though Maculinea rebeli caterpillars live more intimately with their host. We conclude that chemical mimicry enables Maculinea larvae to be accepted as colony members by worker ants, but that caterpillars and pupae of both predatory and cuckoo butterflies employ acoustical mimicry of queen ant calls to elevate their status towards the highest attainable position within their host's social hierarchy.

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    • "Lycaenid immatures have a variety of other adaptations for entraining ant attendance. Some larvae and pupae produce substrate-borne vibrations that attract ants (Downey & Allyn, 1973; DeVries, 1990; Travassos & Pierce, 2000), and at least one parasitic species that lives in ant nests mimics the vibrational signals of the ant queen (Barbero et al., 2009). Many species also have dendritic setae, although the function of these is still a matter of debate (Common & Waterhouse, 1981). "
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    • "The high number of worker ants leads to a low relatedness between nest-mates. A greater variance in nest-mates acoustic signals leads to a higher likelihood of being infested [14]. Through this indicator, the larva can decide the optimal point to leave the colony before it is discovered by other ants as depicted in Figure 1. "
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