1 research outputs found
Chemical cues involved in the attraction of the oligolectic bee Hoplitis adunca to its host plant Echium vulgare
11 páginas, 6 figuras , 1 tabla.Host recognition is a key process in oligolectic bees but the mechanisms through which
they find and recognize appropriate pollen host plant are not entirely clear. Hoplitis adunca
is a monolectic bee collecting pollen only from Echium spp. (Boraginaceae). We aimed to
test whether Echium vulgare floral scent plays a major role in the attraction of H. adunca
females, and to identify components of E. vulgare scent that may be involved in this specific
attraction. We used a combination of behavioral and chemical (GC/GC–MS, PTR-MS)
analyses. In order to identify the chemical cues likely to be involved in the specific
attraction of H. adunca, we compared the scent of fresh flowers, nectar, pollen, and whole
plants of E. vulgare and Anchusa officinalis, another Boraginaceae, which does not attract H.
adunca. H. adunca females were attracted to the scent of E. vulgare flowers when offered
against a blank or against the scent of A. officinalis flowers. However, H. adunca females
were not attracted to the scent of A. officinalis flowers when offered against a blank. The
emission spectra of the two plant species differed markedly, as did the emission spectra of
various flower components (pollen, nectar and whole flowers) within a species. Pollen
presented a low volatile release, but emitted significantly higher amounts of mass 55
(butanal, 1,3-butadiene, or other volatiles of molecular mass 54), and mass 83 (hexanal,
hexenols, hexenyl acetate, or other volatiles of molecular mass 82) in E. vulgare than in A.
officinalis. Nectar produced a particular emission spectrum with high emission rates of
masses 109 and 123. Mass 109 may likely correspond to 1,4-benzoquinone, a volatile
specifically measured in E. vulgare in parallel studies to this one. The flower emission
spectrum was mainly a combination of the pollen and the nectar scents, although it also
contained additional volatile compounds such as those of mass 63 or mass 81. As for
terpenes, E. vulgare emitted limonene, longicyclene, junipene, trans-caryophyllene and
a-humulene, that were not detected in A. officinalis, and the most emitted monoterpenes
were a-pinene, junipene and limonene whereas the most emitted terpenoid by A. officinalis was a-pinene. After identifying these chemical cues, olfactory/behavioural assays
with specific volatiles and combinations of volatiles are necessary to understand the
chemical interactions of the H. adunca-E. vulgare system.This research was supported by Spanish MEC grants CGL-2006-04025/BOS, CGL2010-17172, and Consolider-Ingenio
Montes CSD2008-00040, the European Science Foundation “VOCBAS” program, and a Catalan government SGR2009-458
grant.Peer reviewe