Alarm signals attraction

Aphidius uzbekistanicus Aphidius sp. Host alarm signal [attraction] (E)-p-Farnesene 48 [88]... 

Chivers DP, Brown GE, Smith RJF (1996) The evolution of chemical alarm signals attracting predators benefits alarm signal senders. Am Nat 148 649-659... 

Alarm signals produced by stressed hosts also attract parasitoids. For example, stressed aphids (Aphidius sp.) were attractive to female parasitoids of two... 

Not all releaser pheromones are sex attractants. One alternative example of a releaser pheromone is the sending out of an alarm message, warning other members of the species that some threat is at hand. The California sea anemone Anthopleura elegantissima provides a neat example of alarm signaling. 

The variety of functional niches occupied by these injury-released compounds suggests conflicts between the requirements of various functions . Selection on senders and receivers may each exert pressure on the system. For example, predator attraction as a defense mechanism may conflict with abrasive spawning behavior and resistance to digestive processes may conflict with optimal breakdown rates for alarm signaling. 

Predator attraction as a strategy favoring senders would favor chemical secretions that were easily detected by predators. Both alarm signaling and predator attraction should favor easy detection. However, there could be conflict between attracting predators and repelling conspecifics, so a compound or mix of compounds that was a general attractant or repellant would favor one function over the other. If that is so, predator attraction seems to have won out in fathead minnows. However, compounds that attract predators are best avoided by prey, increasing selection on prey for defensive responses to the cue. 

Taxonomic Comparisons. Obviously there are many variations on the basic injury released alarm pheromone theme in fishes and other organisms. A more comprehensive examination of the distribution and variations of this phenomenon might reveal patterns. For example, are there alarm substances that are predator attractants and others that are predator repellants Are some ecological niches more amenable to chemical alarm signaling than others Electrical ostariophysans, for example, seem to lack the alarm pheromone system (Pfeiffer 1977) but may use their electrical signals in some comparable manner. 

Mathis, A., Chivers, D.P. R.J.F Smith. 1995. Chemical alarm signals predator-deterrents or predator attractants Am. Nat., 145, 994-1005. 

The preceding falls far short of conveying a true impression of the chemical skills of arthropods. Excluded from our discussion are the diverse signaling agents that mediate such vital insectan functions as food location, mate attraction, social bonding, and alarm communication. Other contributors to this colloquium address some of these topics. While... 

There is some evidence that a compound may serve different signaling functions depending on the context and concentration in which it is released. For example, neral (2) functions as an alarm pheromone for Schwiebea elongata at higher doses (Kuwahara et al., 2001), whereas at lower doses, it has been shown to attract (and possibly arrest) females (Nishimura et al., 2002). 

Insects communicate by releasing pheromones—chemical substances that other insects of the same species detect with their anteimae. There are sex, alarm, and trail pheromones, and many of these are alkenes. Interfering with an insect s ability to send or receive chemical signals is an environmentally safe way to control insect populations. For example, traps with synthetic sex attractants have been used to capture such crop-destroying insects as the gypsy moth and the boll weevil. Many of the flavors and fragrances produced by certain plants also belong to the alkene family. 

Camphor and <7-limonene are allomones in that the trees which produce them are protected from insect attack by their presence. For instance, Arthur Birch, one of the great terpene chemists of the twentieth century, reported finding d-limonene in the latex exuded by trees of the species Araucaria bidwilli.1 2 These trees are protected from termite attack because the d-limonene they produce is an alarm pheromone for termites that live in the same area. Similarly, antifeedants could be considered to be allomones since the signal generator, the plant, receives the benefit of not being eaten. Myrcene is a kairomone, in that it is produced by the ponderosa pine and its presence attracts the females of the bark beetle, Dendroctonous brevicomis. Geraniol is found in the scent of many flowers such as the rose. Its presence attracts insects to the flower and it can be classified as a synomone since the attracted insect finds nectar and the plant obtains a pollinator. 

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