More than euglossines: the diverse pollinators and floral scents of Zygopetalinae orchids

Abstract

Floral volatile organic compounds (VOCs) play important roles in plant-pollinator interactions. We investigated the reproductive ecology and floral VOCs of Zygopetalinae orchids to understand the relationship between floral scents and pollinators. We performed focal observations, phenological censuses and breeding system experiments in eight species in southeast Brazil. Floral scents were collected and analysed using SPME/GC-MS. We performed multivariate analyses to group species according to affinities of their VOCs and define compounds associated to each plant. Dichaea cogniauxiana was pollinated by weevils which use their developing ovules, while D. pendula was pollinated by the same weevils and perfume-collecting male euglossine bees. The other species were deceit-pollinated by bees. Zygopetalum crinitum was pollinated by carpenter bees, while W. warreana, Z. mackayi and Z. maxillare were bumblebee-pollinated. The latter was also pollinated by Centris confusa. Breeding system varied widely with no association to any pollinator group. Most VOCs are common to other floral scents. Zygopetalum crinitum presented an exclusive blend of VOCs, mainly composed of benzenoids. The scents of Pabstia jugosa, Promenaea xanthina and the Zygopetalum spp. were similar. The bumblebee-pollinated species have flowering periods partially overlapped, thus neither phenology nor pollinators constitute hybridization barriers among these species. Euglossines are not the only pollinators of Zygopetalinae. Different VOCs, size and lifespan of flowers are associated with distinct pollinators. A distinctive VOC bouquet may determine specialisation in carpenter bees or male euglossines within bee-pollinated flowers. Finally, visitation of deceit-pollinated flowers by perfume-collecting euglossines allows us to hypothesise how pollination by this group of bees had evolved.

Headspace Solid Phase Microextraction Coupled to GC/MS for the Analysis of Volatiles of Honeys from Arid and Mediterranean Areas of Algeria

“…[16 -18] 1,7 ]decan-5-one (major compounds) was identified in receptive stage during pollination of the flower by the bee, [21] whereas 2,6-bis (1,1-dimethylethyl)-4-(1-oxopropyl)phenol was detected exclusively in the pollinating plants. [22] Indeed, 2,4-bis(1,1-dimethylethyl)phenol was also detected in our samples with non-negligible amounts, it was already detected in the bee stomach extracted by dichloromethane. [23] These last three compounds have a high probability of being synthesized by bees (their source is the bee).…”

“…Methyl 3,4‐dimethoxybenzoate was previously identified in honey and bee pollen . 2,2,6,6,7‐Tetramethyl‐10‐oxatricyclo[4.3.0.1 1,7 ]decan‐5‐one (major compounds) was identified in receptive stage during pollination of the flower by the bee, whereas 2,6‐bis(1,1‐dimethylethyl)‐4‐(1‐oxopropyl)phenol was detected exclusively in the pollinating plants . Indeed, 2,4‐bis(1,1‐dimethylethyl)phenol was also detected in our samples with non‐negligible amounts, it was already detected in the bee stomach extracted by dichloromethane .…”

“…AHC data for the main components according to the classes formed in different parameters Switzerland due to the relative polarity of PDMS-CAR fiber compared to PDMS.In addition, a significative effect of the fiber coating on the chemical classes composition was noted (Figure 2andTable 1) as benzene derivatives (PDMS(22 …”

Does reproductive isolation reflect the segregation of color forms in Spiranthes sinensis (Pers.) Ames complex (Orchidaceae) in the Chinese Himalayas?

“…Pollination by polylectic and/or polyphagic bees are common within the Orchidaceae (Dressler, ; Nunes et al., ; van der Pijl & Dodson, ). Darwin () may have been the first to document the pollination of a Spiranthes species by a Bombus species.…”

“…This was not comparable to the interspecific and intergeneric isolation described in the pollination of related epidendroid orchids (Dressler, ) sharing the same euglossine bee pollinators. These taxa remain isolated by morphological differences in column and labellum architecture ( Pedicularis‐ type isolation, sensu Nunes et al., and Schiestl & Schlüter, ). When the same species of euglossine bee collects scents from several coblooming orchids, pollinaria are deposited on different dorsal and ventral parts of the bee's body (head vs. thorax, vs. abdomen vs. leg) avoiding interspecific hybridization (Dressler, ).…”