"
Johnson, Steven D. , Allan Ellis and Stefan Dötter
2007 'Specialization for pollination by beetles and wasps: the role
of
lollipop hairs and fragrance in Satyrium microrrhynchum (Orchidaceae)' in
American Journal of Botany, 94: 47-55.
School of Biological and Conservation Sciences, University of
KwaZulu-Natal, Private Bag X01, Scottsville, Pietermaritzburg 3209, South
Africa;
and
Department of Plant Systematics, University of Bayreuth,
Universitätsstrasse 30, 95447 Bayreuth, Germany
ABSTRACT
Exposed nectar presentation is a key trait in flowers specialized for
pollination by short-tongued insects. We investigated the pollination of
Satyrium microrrhynchum, a rare South African orchid in which nectar is
secreted as droplets on long floral hairs ("lollipop hairs") at the mouth
of a shallow labellum. Our observations indicate that this orchid is
pollinated specifically by two insect species: a cetoniid beetle
(Atrichelaphinus tigrina) and a pompilid wasp (Hemipepsis hilaris). Both
insects have short mouthparts and remove nectar from the hairs with
sweeping motions of their mouthparts. Pollinaria become attached to the
upper surface of their heads while they feed on the nectar. Beetles damage
the hairs while feeding, which may explain the positive relationship
between hair damage and pollination success in plants of S. microrrhynchum
from populations where beetles were common. The orchid has cryptic
green-yellow flowers with spectral reflectance similar to that of its
leaves. The fragrance from plants in three populations, analyzed using gas
chromatography coupled to mass spectrometry, was dominated by various
terpenoids; linalool was the most abundant. Plants in different populations
emitted similar compounds, but eugenol and derivatives of this compound
were found in only one of the three populations. In an electrophysiological
study (gas chromatography coupled to electroantennography), using antennae
of A. tigrina, clear signals were elicited by some of the floral scent
compounds."
URL : http://www.amjbot.org/cgi/content/abstract/94/1/47
*************
Regards,
VB
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