Hindawi Publishing Corporation Psyche Volume 2012, Article ID 342157, 5 pages doi:10.1155/2012/342157 Editorial Ants and Their Parasites Jean-Paul Lachaud, 1, 2 Alain Lenoir, 3 and Volker Witte 4 1 Centre de Recherches sur la Cognition Animale, CNRS-UMR 5169, Universit´ e de Toulouse, UPS, 118 route de Narbonne, 31062 Toulouse Cedex 09, France 2 Departamento de Entomolog´ ıa Tropical, El Colegio de la Frontera Sur, Avenida Centenario Km. 5.5, AP 424, 77014 Chetumal, QRoo, Mexico 3 IRBI, UMR CNRS 7261, Facult´ e des Sciences, Universit´ e Franc ¸ois Rabelais, Parc de Grandmont, 37200 Tours, France 4 Department Biologie II, Ludwig-Maximilians Universit¨ at M¨ unchen, Großhaderner Straße 2, 82152 Planegg-Martinsried, Germany Correspondence should be addressed to Jean-Paul Lachaud, jlachaud@ecosur.mx Received 23 February 2012; Accepted 23 February 2012 Copyright © 2012 Jean-Paul Lachaud et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Ants accumulate and protect collective resources and, with the exception of nomadic species, live in a nest which is considered to be one of the bases of the evolution of eusociality. Resources and/or protective services provided by ant colonies are exploited in manifold ways by an amazing diversity of other organisms acting as guests and/or parasites: viruses, bacteria, fungi, sporozoa, amoeba, ciliates, nematodes, trematodes, cestodes, mollusks, diplopods, crus- taceans, mites, spiders, and a large variety of parasitic or par- asitoid insects. Such associations can be obligatory or facul- tative, permanent or temporary, harmful or beneficial for the host. Due to the diversity of interactions, an understanding of the nature of these relationships and the mechanisms of integration used by parasites as well as the defense strategies developed by their potential host remains a challenge. Parasites certainly increase specific selection pressures on colony phenotype, and they may also shape the composition and dynamics of ant communities. Over the past two decades there has been a growing interest in the impact of parasites on colony phenotype, and their role in the ecology and evolution of their hosts. Despite the apparent importance of ant parasites, detailed knowledge is lacking, for example, about their diversity and abundance or selection pressures imposed through parasitism on host reproductive strategies. Parasitism in ants has attracted the attention of numer- ous scientists in the last two centuries (see the numerous publications on this topic by authors like E. W. Janson, A. Forel, C. Janet, E. Wasmann, H. Viehmeyer, J.-J. Kieffer, K. Escherich, W. M. Wheeler, H. St. J. K. Donisthorpe, W. M. Mann, C. Rettenmeyer, E. O. Wilson, B. H¨ olldobler, D. Kistner, U. Maschwitz, and P. Schmid-Hempel among others). Since the synthesis of Kistner in 1982 [1] and of Schmid-Hempel in 1998 [2], only one complete review has been published [3] (but see also [4] for social parasites) and, in spite of the accumulation of much information in the last decades, this meaningful topic has not been brought together in a specific issue for a long time. This special issue, of course, cannot cover all possible ant parasites, but it examines a wide range of species: viruses, bacteria, fungi, nematodes, silverfishes, flies, butterflies, beetles, spiders, wasps, and ants themselves. It is divided into two main sections: (1) behavioral and ecological aspects of parasitism, in which existing associations are reviewed and discussed, some new associations are described, and some concepts are reanalyzed in a more up-to-date integrative vision; (2) infection, impact on ants and biological control, in which particular effort has been made to provide both an analytical review of the experimental material actually available and a proposal of guidelines for future research on the topic. Behavioral and Ecological Aspects of Parasitism. Numerous species take advantage of the supplies of other organisms and cleptobiosis, a quite common phenomenon among animals, also occurs at ants’ expenses. M. D. Breed et al. review concepts linked to food stealing in social insects, distinguishing cleptobiosis from some related phenomena, and place this knowledge in ecological and evolutionary contexts. In most cases, success in parasitizing ants depends largely on the degree of resemblance to the host, which varies considerably among the diverse mimetic parasites found in