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Sex Attractant Pheromones of Virgin Queens of Sympatric Slave-Making Ant Species in the Genus Polyergus, and their Possible Roles in Reproductive Isolation
Species of the ant genus Polyergus are social parasites that steal brood from colonies of their hosts in the closely related genus Formica . Upon emergence as adults in a mixed population, host Formica workers carry out all the normal worker functions within the Polyergus colony, including foraging,...
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Published in: | Journal of chemical ecology 2018-06, Vol.44 (6), p.547-555 |
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Main Authors: | , , , , , |
Format: | Article |
Language: | English |
Subjects: | |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Species of the ant genus
Polyergus
are social parasites that steal brood from colonies of their hosts in the closely related genus
Formica
. Upon emergence as adults in a mixed population, host
Formica
workers carry out all the normal worker functions within the
Polyergus
colony, including foraging, feeding, grooming, and rearing brood of the parasitic
Polyergus
ants. Some unmated
Polyergus
gynes (queens) run in the raiding columns of their colonies and attract males by releasing a pheromone from their mandibular glands. There are two
Polyergus
species groups in North America: an eastern
P. lucidus
group and a western
P. breviceps
group. One species of each of these groups,
P. lucidus
Mayr and
P. mexicanus
Emery, are sympatric in Missouri. In this study, we characterized the sex pheromones of virgin queens of two species of the
P. lucidus
group (
P. lucidus
sensu stricto and
P. sanwaldi
) and one species of the
P. breviceps
group (
P. mexicanus
), and compared these with the previously identified sex pheromone of
P. topoffi
of the
P. breviceps
group. We then used sex pheromone blends reconstructed from synthesized components of the two groups to test their efficacy at reproductively isolating these species. We found that methyl 6-methylsalicylate is conserved as the major component of the pheromone blends for both
Polyergus
species groups; however, methyl (
R
)-3-ethyl-4-methylpentanoate is the species-specific minor component produced by
P. lucidus
group queens, and (
R
)-3-ethyl-4-methylpentan-1-ol is the crucial minor component for
P. breviceps
group queens. The optimal ratio of the major and minor components for
P. lucidus
group queens was about 100:1 salicylate to ester. In concurrent field trials in Missouri, males of
P. lucidus
sensu stricto and
P. mexicanus
(a member of the
P. breviceps
group) were attracted almost exclusively to their particular blends of sex pheromone components. To our knowledge, this is the first example of a possible sex-pheromone-based reproductive isolating mechanism in ants. |
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ISSN: | 0098-0331 1573-1561 |
DOI: | 10.1007/s10886-018-0966-9 |