Pheromone-mediated behaviour

Pheromones have been defined as substances released by an individual into the external environment which precipitate a particular reaction in a conspecific (Karlson and Liischer 1959). Pheromones are used by species in a variety of phyla (see e.g. McClintock, Jacob, Zelano and Hayreh 2001), and there exist many examples of pheromone-mediated behaviour in a wide range of mammals, particularly in relation to mating behaviour and maturation (see e.g. Vandenbergh 1983). In humans however, the question of whether pheromones influence behaviour was recently listed by Science magazine as one of the top 100 outstanding questions (Anon 2005). A recent review of behavioural and anatomical studies relating to the function of pheromones in human interactions concluded that while a small number were unambiguously supportive , none seemed ultimately conclusive (Hays 2003). 

Kurtovic A et al (2007) A single class of olfactory neurons mediates behavioural responses to a Drosophila sex pheromone. Nature 446 542-546 Kwon JY et al (2007) The molecular basis of C02 reception in Drosophila. Proc Natl Acad Sci USA 104 3574-3578... 

Sneddon LU, Huntingford FA, Taylor AC, Clare AS (2003) Female sex pheromone-mediated effects on behaviour and consequences of male competition in the shore crab (Carcinus maenas). J Chem Ecol 29 55-70... 

Central/Tertiary structures The fish olfactory bulb is a fourlayered structure much as in higher vertebrates. Within the 2nd layer, the first synapse for olfactory input is on the dendrites of the mitral cells (MC). About 1000 ORN axons converge on one MC, a ratio similar to mammals. The MC output, from cells at various levels, leads into several glomeruli and receives (inhibitory) input from granule cells. The latter also innervate a distinct cell type in the MC layer of teleosts — the ruffed cells (RC), with which they have reciprocal synapses [Fig. 2.18(a)] both relay cells send ascending fibres to forebrain centres (Kosaka and Hama, 1982). The RC are unlike the MC since they are not stimulated by the ORNs directly. Their interactions (Chap. 5) may contribute to the processing of pheromonal stimuli (Zippel, 2000). The main bulbar pathways project to several nuclei in the forebrain via two ipsilateral tracts, the lateral and medial [Fig. 2.18(b)], the latter mediates sexual behaviour and the former probably other behaviours (Hara,... 

Domes, K. M., Adkins Regan, E. and Halpem, B. P. (1997) Sensitivity and behavioural responses to the pheromone androstenone are not mediated by the vomeronasal organ in domestic pigs. Brain Behav. Evolut. 49, 53-62. 

Another unusual structure was identified from cereal leaf beetles, Oulema melanopus ( )-8-hydroxy-6-methyl-6-octen-3-one 199 was found to be a male-specific volatile. Electrophysiological investigations showed a sensitive detection of 199 by both sexes which is consistent with a male-produced aggregation pheromone [367]. The behaviour mediating capacity of the compound needs to be proven. 

In some flea beetles, Phyllotreta and Aphthona spp., species specific, male produced blends of himachalene derivatives like 201,202, and 203 were identified. Structure elucidation was carefully carried out on the basis of spectroscopic methods, micro reactions, and independent syntheses [370,371]. Compounds 201,202,203 are perceived by both male and female antennae, as would be expected for an aggregation pheromone. Investigations on the behaviour mediating capacity of the compounds are ongoing. 

Appel, A. G. and Rust, M. K. (1983). Temperature-mediated sex pheromone production and response of the American cockroach. Journal of Insect Physiology 29 301-305. Barth, R. H., Jr (1964). The mating behavior of Byrsotria fumigata (Guerin) (Blaberidae, Blaberinae). Behaviour 23 1-30. 

Vanderwel D., Currie R. W., Griffith O. and Hastings C. (2003) Clarification of the roles of the female-produced sex pheromones in mediating the mating behaviour of the yellow mealworm, Tenebrio molitor L. (Coleoptera Tenebrionidae). J. Chem. Ecol. In preparation. 

Sexual communication between sexes in Lepidopteran species is mediated mainly by sex pheromones, which are volatile compounds used by the female to attract potential mates from a distance [18]. In moths, sex pheromones play an important role in the elicitation of mating behaviour, and are, therefore, crucial for successful mating. They are synthesised by females in a specialised gland, which is a modification of the inter-segmental membrane located between the eighth and ninth abdominal segments [19, 20]. The pheromone is produced within the epithelial cells, transported through the cuticle via special porous cuticular spines and disseminated from the surface [19, 20]. 

While pheromones are known to mediate a variety of behaviours in other mammals, the human vomeronasal organ (VNO), which conveys information about pheromone eoncentration to the brain, was believed to be absent or atrophied in adults. It was also believed to lack any... 

The mediators involved in this type of interaction are the pheromones, which act in various ways they may (1) cause a momentery behavioural modification, immediate but potentially reversible (releaser pheromone) (2) induce a series of modifications at the nervous and endocrinous levels foUowing prolonged stimulation (primer pheromones) or (3) lead to a phenotypic modification of the receiving individual when they act at certain critical periods (imprinting pheromones). 

Enantiomeric composition of a pheromone is instrumental with respect to the behaviour mediating capacity of the signal. This especially stands for bark beetles (Coleoptera Curculionidae, Scolytinae) where even different populations of the same species employ pheromone of different enantiomeric composition (Seybold, 1993 Miller et al., 1996). Enantioselective production of, and response to pheromones has been demonstrated in many species of Scolytinae subfamily (Birch, 1984 Borden, 1985 Byers, 1989). Electrophysiological studies have revealed that species such as Ips pini Say, 1. typographus (L.), I. paraconfusus Lanier, Scolytus multistriatus (Marsham), S. scolytus (F.) and Trypodendron lineatum (Olivier) and many others have olfactory receptor cells specific to optical isomers of aggregation pheromones (Mustaparta et al., 1980,1984 Wadhams et al., 1982 Tommeras et al., 1984). 

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