The chemistry of social regulation: multicomponent signals in ant societies.

Abstract

Chemical signals mediating communication in ant societies are usually complex mixtures of substances with considerable variation in molecular composition and in relative proportions of components. Such multicomponent signals can be produced in single exocrine glands, but they can also be composed with secretions from several glands. This variation is often functional, identifying groups or specific actions on a variety of organizational levels. Chemical signals can be further combined with cues from other sensory modalities, such as vibrational or tactile stimuli. These kinds of accessory signals usually serve in modulatory communication, lowering the response threshold in the recipient for the actual releasing stimulus. Comparative studies suggest that modulatory signals evolved through ritualization from actions originally not related to the same behavioral context, and modulatory signals may further evolve to become independent releasing signals.The impressive diversity and ecological dominance of ant societies are in large part due to their efficient social organization and the underlying communication system. The functional division into reproductive and sterile castes, the cooperation in rearing the young, gathering food, defending the nest, exploring new foraging grounds, establishing territorial borders, and discriminating and excluding foreigners from the society are regulated by the precise transmission of social signals in time and space.Probably the best-studied communication behavior in ants is chemical communication, but other sensory modalities, such as mechanical cues, also play an important role in the formation of multicomponent signals in ant communication. Chemical releasers are produced in a variety of exocrine glands, and considerable progress has been made in chemically identifying many of these glandular secretions (for reviews see refs. 1 and 2). In this essay I will not emphasize, however, the natural product chemistry of ant pheromones, but rather concentrate on the proposition that communication in ant societies is often based on multicomponent signals, on nested levels of variation in chemical and other cues, which feature both anonymous and specific characteristics (3). Pheromone BlendsSingle exocrine glands usually produce mixtures of substances. The Dufour's gland secretions of the carpenter ant Camponotus ligniperda, for example, include at least 41 compounds (4), and the mandibular glands of the weaver ant Oecophylla longinoda contain over 30 compounds, in colony-specific pro-The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.portions (5, 6). The identification of these components has mostly out-paced an understanding of their function, but in a few cases we begin to realize that the blends are part of the complex behavior-releasing key stimulus. In Oecophylla, for example, the mixture of mandibular gland secretions...

Recruitment and trail communication in two species ofMessorants (Hymenoptera, Formicidae)

“…This could also be the case of M. minor and M. wasmanni, whose workers emit strong stridulations as soon as they find a conspicuous food source. We suggest that these ants produce stridulations as additional shortrange recruitment signals that probably modulate the responses of nestmates to chemical stimuli and facilitate recruitment towards the food source (see Hölldobler, 1995). It is also possible that stridulations are merely a 'by-product' of gastral movements during cutting or that (2-9) 4.7 (1-7) 9.7 (2-14)…”

“…The efficacy of communication in ants is sometimes improved by the combination of chemical signals with stimuli from other sensory modalities (such as stridulations) that lower the response threshold in the receiver (Hölldobler, 1995). The role of stridulations in the context of food recruitment has been clearly shown in Aphaenogaster cockerelli André, 1893, A. albisetosus Mayr, 1886, Messor capitatus, M. structor, and Atta cephalotes (Linné, 1758 (Markl & Hölldobler, 1978;Hahn & Maschwitz, 1985;Baroni Urbani et al, 1988;Roces et al, 1993).…”

Naked mole-rats recruit colony mates to food sources

“…The glands that are the source of ants' odour trails have been identified (reviewed by Hölldobler & Wilson 1990, pages 227-249;Hölldobler 1995). In eastern tent caterpillars (Malacosoma americanum : Fitzgerald 1995) and some ants, special behaviour patterns (e.g.…”

“…In many other ant species (reviewed by Gabba & Pavan 1970;Hölldobler & Wilson 1990, pp. 265-273;Hölldobler 1995), a few species of stingless bees (Michener 1974;Lindauer 1961) and most species of tent caterpillars (Fitzgerald 1995), foragers lay chemical trails to food. Finally of course, the dance language of honey bees, Apis mellifera, is legendary for its precision and accuracy (von Frisch 1967;Seeley 1995).…”

Trail Pheromones in Pest Control

“…The distance through which a pheromone may transmit a message is a function of the volatility of the compound, its chemical stability in air, the rate of diffusion, the olfactory efficiency of the receiver, and wind speed and direction (Fitzgerald & Underwood, 1998). In ants, trail longevity varies from minutes in Aphaenogaster albisetosus (Hölldobler et al, 1995), to 2 h in M. lepineyi and M. bicolor , to 1 h in M. niloticum, M. mayri, and M. najrane (Mashaly, 2010), to 105 mins in P. longicornis and P. vividula (Mashaly et al, 2008), to 1 hr in M. meridionalis and M. foreli (Mashaly, 2011) and to several weeks in some Eciton species (Torgerson & Akre, 1970). Short-lived trails can rapidly modulate recruitment to ephemeral food sources, whereas long-lived trails will be more suited to persistent, or recurrent, food sources (Fitzgerald & Underwood, 1998).…”