Journal of Chemical Ecology (1999) 25, 2505-2525

J. Steven McElfresh and Jocelyn G. Millar (1999)
Geographic variation in sex pheromone blend of Hemileuca electra from southern California
Journal of Chemical Ecology 25 (11), 2505-2525
Abstract: Differences were found in the pheromonally mediated mate location systems of two subspecies of Hemileuca electra, H. electra electra (Hee) and H. e. mojavensis (Hem), from southern California. Hem female pheromone gland extracts contained eight times as much (10E,12Z)-hexadeca-10,12-dienal (E10,Z12-16:Ald) and half as much hexadecyl acetate (16:Ac) as Hee extracts. Relative amounts of the other major component of the pheromone blends, (10E,12Z)-hexadeca-10,12-dien-1-ol (E10,Z12-16:OH) did not differ between the two subspecies. In coupled gas chromatography-electroantennogram studies, responses of male antennae to 1:1:1 mixtures of the three principal components (E10,Z12-16:Ac, E10,Z12-16:OH, E10,Z12-16:Ald) also differed, with Hem antennae producing significantly larger responses to E10,Z12-16:Ald and significantly smaller responses to 10E,12Z-16:Ac than Hee. In field trials, male Hem were attracted to Hem females in preference to Hee females. Males of a second species, H. burnsi, which is sympatric with Hem but not Hee, also were attracted to females of Hee transported to their range. Field tests of blends of synthesized pheromone components confirmed that male Hem preferred E10,Z12-16:Ald ratios of 10-100% of the major component, E10,Z12-16:Ac, whereas males of Hee and H. burnsi responded optimally to ratios of 0.3-1% E10,Z12-16:Ald to E10,Z12-16:Ac. 16:Ac added to lures increased attraction of Hee but not Hem males. The data presented are consistent with reproductive character displacement, whereby the Hem subspecies has modified its pheromone-based mating system to reduce interference from sympatric H. burnsi.
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Link to article at publishers website
Database assignments for author(s): Jocelyn G. Millar

Research topic(s) for pests/diseases/weeds:
pheromones/attractants/traps

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Hemileuca (genus)