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Intraspecific geographic variation of fragrances acquired by orchid bees in native and introduced populations.

Ramírez SR, Eltz T, Fritzsch F, Pemberton R, Pringle EG, Tsutsui ND - J. Chem. Ecol. (2010)

Bottom Line: We recorded a total of 292 fragrance compounds from hind-leg extracts, and found that overall perfume composition was different for each population.We detected a pronounced chemical dissimilarity between native (Mesoamerica) and naturalized (U.S.) populations that was driven both by proportional differences of common compounds as well as the presence of a few chemicals unique to each population group.By comparing incidence values and consistency indices across populations, we identify putative functional compounds that may play an important role in courtship signaling in this species of orchid bee.

View Article: PubMed Central - PubMed

Affiliation: Environmental Science, Policy & Management, University of California Berkeley, 137 Mulford Hall #3114, Berkeley, CA 94720, USA. sramirez77@berkeley.edu

ABSTRACT
Male orchid bees collect volatiles, from both floral and non-floral sources, that they expose as pheromone analogues (perfumes) during courtship display. The chemical profile of these perfumes, which includes terpenes and aromatic compounds, is both species-specific and divergent among closely related lineages. Thus, fragrance composition is thought to play an important role in prezygotic reproductive isolation in euglossine bees. However, because orchid bees acquire fragrances entirely from exogenous sources, the chemical composition of male perfumes is prone to variation due to environmental heterogeneity across habitats. We used Gas Chromatography/Mass Spectrometry (GC/MS) to characterize the perfumes of 114 individuals of the green orchid bee (Euglossa aff. viridissima) sampled from five native populations in Mesoamerica and two naturalized populations in the southeastern United States. We recorded a total of 292 fragrance compounds from hind-leg extracts, and found that overall perfume composition was different for each population. We detected a pronounced chemical dissimilarity between native (Mesoamerica) and naturalized (U.S.) populations that was driven both by proportional differences of common compounds as well as the presence of a few chemicals unique to each population group. Despite these differences, our data also revealed remarkable qualitative consistency in the presence of several major fragrance compounds across distant populations from dissimilar habitats. In addition, we demonstrate that naturalized bees are attracted to and collect large quantities of triclopyr 2-butoxyethyl ester, the active ingredient of several commercially available herbicides. By comparing incidence values and consistency indices across populations, we identify putative functional compounds that may play an important role in courtship signaling in this species of orchid bee.

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Boxplots of the number of volatile exogenous compounds per capita in fragrances of male Euglossa aff. viridissima in native and introduced populations
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Fig3: Boxplots of the number of volatile exogenous compounds per capita in fragrances of male Euglossa aff. viridissima in native and introduced populations

Mentions: We registered a total of 333 compounds in hind leg extracts of 114 males sampled from seven populations (Fig. 1). By comparing the chemical profiles of hind leg extracts against those from labial glands (Fig. 2) we determined that 41 compounds were produced in the bees’ labial glands (endogenous origin), and included straight chain hydrocarbons, acetates, diacetates, and alcohols (Supplementary Material Appendix 2). The remaining 292 compounds are thus exogenous in origin, and included monoterpenes, sequiterpenes, bicyclic sesquiterpenes, triterpenes, and other compounds (Table 1). The per-capita number of exogenous compounds across all populations ranged from 1 to 65 chemicals (average 21.50 ± 12.66) with marginally similar means in all seven populations (ANOVA F = 3.2118, P = 0.075). On average, male bees from Fern Forest (U.S.) exhibited the lowest number of compounds per capita (15.83 ± 10.08), whereas El Remate (Mexico) exhibited the highest number (29.23 ± 6.24; Fig. 3). When the two U.S. populations were combined, they had significantly fewer compounds per individual (17.46 ± 10.78) than all Mesoamerican populations combined (24.14 ± 13.17; ANOVA F = 8.0419, P = 0.005).Fig. 3


Intraspecific geographic variation of fragrances acquired by orchid bees in native and introduced populations.

Ramírez SR, Eltz T, Fritzsch F, Pemberton R, Pringle EG, Tsutsui ND - J. Chem. Ecol. (2010)

Boxplots of the number of volatile exogenous compounds per capita in fragrances of male Euglossa aff. viridissima in native and introduced populations
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2908462&req=5

Fig3: Boxplots of the number of volatile exogenous compounds per capita in fragrances of male Euglossa aff. viridissima in native and introduced populations
Mentions: We registered a total of 333 compounds in hind leg extracts of 114 males sampled from seven populations (Fig. 1). By comparing the chemical profiles of hind leg extracts against those from labial glands (Fig. 2) we determined that 41 compounds were produced in the bees’ labial glands (endogenous origin), and included straight chain hydrocarbons, acetates, diacetates, and alcohols (Supplementary Material Appendix 2). The remaining 292 compounds are thus exogenous in origin, and included monoterpenes, sequiterpenes, bicyclic sesquiterpenes, triterpenes, and other compounds (Table 1). The per-capita number of exogenous compounds across all populations ranged from 1 to 65 chemicals (average 21.50 ± 12.66) with marginally similar means in all seven populations (ANOVA F = 3.2118, P = 0.075). On average, male bees from Fern Forest (U.S.) exhibited the lowest number of compounds per capita (15.83 ± 10.08), whereas El Remate (Mexico) exhibited the highest number (29.23 ± 6.24; Fig. 3). When the two U.S. populations were combined, they had significantly fewer compounds per individual (17.46 ± 10.78) than all Mesoamerican populations combined (24.14 ± 13.17; ANOVA F = 8.0419, P = 0.005).Fig. 3

Bottom Line: We recorded a total of 292 fragrance compounds from hind-leg extracts, and found that overall perfume composition was different for each population.We detected a pronounced chemical dissimilarity between native (Mesoamerica) and naturalized (U.S.) populations that was driven both by proportional differences of common compounds as well as the presence of a few chemicals unique to each population group.By comparing incidence values and consistency indices across populations, we identify putative functional compounds that may play an important role in courtship signaling in this species of orchid bee.

View Article: PubMed Central - PubMed

Affiliation: Environmental Science, Policy & Management, University of California Berkeley, 137 Mulford Hall #3114, Berkeley, CA 94720, USA. sramirez77@berkeley.edu

ABSTRACT
Male orchid bees collect volatiles, from both floral and non-floral sources, that they expose as pheromone analogues (perfumes) during courtship display. The chemical profile of these perfumes, which includes terpenes and aromatic compounds, is both species-specific and divergent among closely related lineages. Thus, fragrance composition is thought to play an important role in prezygotic reproductive isolation in euglossine bees. However, because orchid bees acquire fragrances entirely from exogenous sources, the chemical composition of male perfumes is prone to variation due to environmental heterogeneity across habitats. We used Gas Chromatography/Mass Spectrometry (GC/MS) to characterize the perfumes of 114 individuals of the green orchid bee (Euglossa aff. viridissima) sampled from five native populations in Mesoamerica and two naturalized populations in the southeastern United States. We recorded a total of 292 fragrance compounds from hind-leg extracts, and found that overall perfume composition was different for each population. We detected a pronounced chemical dissimilarity between native (Mesoamerica) and naturalized (U.S.) populations that was driven both by proportional differences of common compounds as well as the presence of a few chemicals unique to each population group. Despite these differences, our data also revealed remarkable qualitative consistency in the presence of several major fragrance compounds across distant populations from dissimilar habitats. In addition, we demonstrate that naturalized bees are attracted to and collect large quantities of triclopyr 2-butoxyethyl ester, the active ingredient of several commercially available herbicides. By comparing incidence values and consistency indices across populations, we identify putative functional compounds that may play an important role in courtship signaling in this species of orchid bee.

Show MeSH