Territoriality pheromones

Horne, E. A. and Jaeger, R. G. (1988). Territorial pheromones of female red-backed salamanders. Ethology 78,143. 

Territorial Pheromones. Males of many species of bumblebees mark selected sites with labial gland products that attract both males and females. These territorial mating spots are "perfumed" with a wide variety of acyclic compounds that appear... 

Jaeger, R. G., Goy, J., Tarver, M., and Marquez, C., 1985, Salamander territoriality Pheromonal markers as advertisement by males,... 

Studies of pheromonal advertisement during territorial defense are, essentially, just beginning. For that reason, in this paper I shall attempt to review what little information is available about territorial pheromones and, additionally, to put this information in the context of the natural history of selected species. 

At this point, I shall discuss the first in this series of defensive tactics the territorial pheromones. 

Nothing is known about the biochemistry of the pheromones used in territorial advertisement. This is unavoidably true partly because the study of territoriality in salamanders is so new, partly because the existence of pheromones has been inferred only from behavioral responses of individuals under experimental conditions, and partly because none of the glands producing the suspected pheromones have been conclusively identified. In short, there is so little background information about territorial pheromonal communication in salamanders that sophisticated studies probably will not be conducted for several years yet. 

In this section, then, I shall review the behavioral evidence for the existence of territorial pheromones, suggest some possible receptors involved, and mention the glands suspected of producing pheromones. 

Virtually all tests of territorial pheromones have involved the response of a receiver salamander in the presence or absence of presumed pheromones from a sender. Four basic experimental designs have been used. 

In summary, virtually all of the information on territorial pheromones (through behavioral inferences of their existence) comes from single species, Plethodon cinereus. Evidence to date indicates that at least males (and perhaps females) place chemical substances on the substrate, that these substances are contained in fecal pellets and are produced in or near the cloaca (though other glandular sources are not ruled out), that these substances tend to deter intruders from entering a marked (territorial) area, and that the aggressive and submissive interactions of territorial residents and intruders are governed in part by these substances (and in part by visual displays). Thus, pheromones, whatever they are, are used by Plethodon cinereus (and perhaps other species of salamanders) to advertise territorial possession. 

Given these data, there is considerable evidence that the nasolabial cirri, and ultimately the chemoreceptors in the nares, are the principal monitors of territorial pheromones. 

The data from Jaeger and Gergits (1979) suggest that female Plethodon cinereus do not produce territorial pheromones, because both conspecific males and females are unresponsive to substrates upon which females have resided. Females lack the vent gland, and indeed they lack all cloacal glands except for the spermatheca (Sever, 1978b). 

Still another factor in spacing conununication system stability is residual activity of a chemical stimulus, which may vary over time according to the insect species and the nature of the message conveyed. For example, the repellent pheromone deposited by Xylocopa bees following extraction of nectar from passion flowers persists for only about 10 minutes, which may coincide with the time required for replenishment of some of the nectar, whereas Oecophylla ants deposit territorial pheromone which persists for up to 12 days, designating areas of continuous exploitation (see Section 11.5). Residual activity... 

Aggressive behavior is released by the territorial pheromone of Oecophylla longinoda, however. This pheromone is located in the drops of brown rectal sac fluid which the workers deposit over the territorial surface. They are particularly active in marking any fresh areas which they may encounter, but established territory is also marked constantly, albeit at a greatly reduced rate. Workers which encounter spots of rectal sac fluid produced by members of another colony inspect them frequently with their antennae, and often adopt threat postures in the complete absence of any foreign ants. Moreover, the presence of their own territorial marks enables workers to recruit faster than workers on alien territory (Hdlldobler and Wilson, 1977a). 

In many species, the trail pheromone is used in two distinct contexts, namely food retrieval and nest emigration. Hdlldobler and Wilson (1978) have distinguished no less than five types of recruitment in the African weaver ant, O. longinoda. The alarm and territorial pheromones of this species have already been discussed, and these, together with the recruitment systems, constitute the most complex use of chemical communication yet discovered in ants. 

HOlldobler, B. and Wilson, E. O. (1977a) Colony-specific territorial pheromone in the African weaver ant Oecophylla longinoda (Latreille). Proc, Nat. Acad. Sci., USA, 74, 2072-5. 

Territorial pheromones These pheromones mark the boundaries of an organism s territory. In dogs, these pheromones are present in the urine. Dogs can thus mark out their territory. 

In general, the same techniques are used to collect stimuli for tests of pheromones used in reproduction as for tests of territorial pheromones. It is possible that in many cases the same pheromones may serve both functions advertisement to potential competitors and to potential mates. Although the collection techniques are similar for both types of pheromones, many studies of sexual advertisement pheromones have focused on aquatic animals (primarily newts) and the techniques described above for terrestrial salamanders have been modified for use in aquatic environments. For example, test animals might be exposed to water from a chamber that had contained another salamander (Dawley 1984b) or from sponges soaked with secretions from other salamanders (Twitty 1955). 

Not surprisingly, many studies have considered attraction/avoidance as indicators of detection of sexual advertisement pheromones (Dawley 1984a, 1984b Walls et al. 1989 Malacame Vellano 1987 Cogalniceanu 1994). These responses are the easiest to quantify and interpretation of the results may be more straightforward for sexual advertisement pheromones than for territorial pheromones (see discussion above). For example, males are predicted to be attracted to females and individuals of either sex should be attracted to potential mates that they find more attractive. 

Jaeger, R.G., J.M. Goy, M. Tarver, C.E. Marquez. 1986. Salamander territoriality pheromonal markers as advertisement by males. Anim. Behav. 34 860-864. 

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