Pheromone population differences

LaForest, S Wu, W. and Lofstedt, C. (1997). A genetic analysis of population differences in pheromone production and response between two populations of the turnip moth, Agrotis segetum. Journal of Chemical Ecology 23 1487-1503. 

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). 

Red-sided garter snakes from different regions of Manitoba, Canada show signs of isolation by chemical cues. In choice tests, males from a hiber-naculum (overwintering den) in central Manitoba preferred females from their own population to females from western Manitoba. Males from western Manitoba showed no preference. When confronted with experimental trails, males made the same choices. This demonstrated that a chemical factor is involved. Furthermore, the sexual attractiveness pheromone of females, a series of ty-9-cis-unsaturated methyl ketones, varies between the populations. Specifically, the... 

A great deal of information on CHCs as chemotaxonomic characters and sex pheromones is available for Drosophilidae. Several species and populations within species have been identified on the basis of hydrocarbon patterns. Studies have shown that CHCs differing between close species or populations often act as pheromones and may participate in prezy-gotic isolation. This section presents examples in which sex-pheromone polymorphism has been used as a basis for quick determination of strain/species (see Table 7.1). In section four of this chapter we deal with the possible role of pheromones in speciation. 

Second, the majority of studies of cuticular lipids have simply listed the compounds present in cuticular extracts, and in some cases compared the lipid profiles of different life stages, populations, or species. Relatively few studies have fractionated extracts to isolate and identify the specific biologically active contact pheromone components from the mixtures of lipids in extracts, and then followed up with reconstruction of active pheromone blends from synthesized compounds to verify the bioactivity. This trend... 

As indicated earlier H. subflexa has recently become the subject of numerous pest control studies due to the potential for population control of H. virescens by a sterile hybrid release program. However, these two species maintain reproductive isolation despite broadly overlapping ranges and intersecting reproductive periods. Hence, barriers to interspecific gene flow are most likely due to differences in their respective sex pheromone communication systems and, as indicated earlier, there are considerable differences in the pheromone gland contents of each. 

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