The best review and most recent synthesis of euglossine bee biology is
D.W. Roubik and P.E. Hanson (2004), Orchid Bees of Tropical America:
Biology and Field Guide; Instituto Nacional de Biodiversidad (INBio),
Santo Domingo de Heredia, Costa Rica.
There are numerous studies that show various levels of relationship
between euglossines and orchids and other flowers. There is little
data to indicate any obligate relationship on a one-on-one basis
between any bee species and any orchid species. Such relationships are
speculative and based on extremely limited observation. In summary on
this matter, Roubik and Hanson determined that "Possibly less than 10%
of the orchid species use a single species of pollinator" and "Just as
most orchids attract several euglossine species, most euglossine
species visit more than one species of orchid."
Orchids and other flowers attractive to euglossine bees do not produce
pheromones in the strict sense. The flowers are producing various
compounds that the bees collect: aromatics by the males and resins by
the female bees. The females use the resins in the construction of
their nests. It remains unknown why the males collect the aromatics,
but the current speculation on available data is focussed on their use
for attracting females in complicated courtship routines. There is
some evidence that cocktails of various aromatics are produced by the
males, that it is these cocktails that are used to seduce the females,
that salivary components may cause changes to these cocktails or
certain components, and that the cocktails are unique to each bee
species. Male and female bees do not seem to visit the same flowers,
and the females are rarely attracted to the same aromatics as produced
by the flowers. An aphrodisiac or sexual stimulate? Maybe. But if
people more time was spent on studying the biology of the bees and
orchids, and less time on sexual vanity drugs, we might have more
knowledge and fewer health problems.
On the conservation side of things, yes, there is copious information
indicating that the reduction of old secondary or primary tropical
forests is inimical to either orchid or euglossine bee existence. Too,
the selective removal of certain tree species from the forest may have
some impact through the removal of preferred growing sites for some
orchids. Although many orchids will colonize regenerated forests,
ongoing studies suggest that the bees may not do so very quickly.
However, the time frames are not narrowed and will vary among the
various forest types. Observations made by me and students last week
in northwestern Costa Rica suggest that 25-30 years of recovery in a
tropical dry forest is insufficient for either orchid or euglossine bee
presence and diversity.
This past Friday evening, my students and I had dinner with Dr. Paul
Hanson and family. Various aspects of the euglossine biology were
discussed, along with our own cerveza (another chemical cocktail, of
sorts) enhanced speculations and hypotheses on the why's and
wherefore's of various bee behaviors. The main conclusions: 1) there
really is still too little information on the flower-bee relationships,
2) basic information elucidating euglossine bee biology is needed, 3)
wise and wealthy individuals and governments (through taxes on
television ministries and the selling of unused military goods) should
contribute generously to furthering orchid-euglossine bee studies, 4)
the answer to orchid-bee relationships probably has something to do
with the number 42 (vis-a-vis Douglas Adams), and 5) innovative
graduate students are welcome to inquire.
Paul
On 18 May 2005, at 05:48 AM, Oliver Sparrow wrote:
I saw an oddity on British television last night on which people on
this network
may be able to expand. The program was concerned with the life and
times of the
Brazil nut, including its pollinators. These Euglossine bees were
shown visiting
an orchid, which with my admitted ignorance of South American orchids
looked
like a Gongora aff. quinquenervis. The commentary said that
"scientists had
shown" that the male bees needed a scent from the flower in "order to
be able to
breed". They went on to say that elimination of the orchid and its
habitat was
therefore also the elimination of the pollinator, and thus the
eventual end for
the Brazil nut.
I assume that the flower has a pheromone, and this is either
attractive to
females (but why don't they and not the males visit?) or bee viagra.
Does anyone
know more about this?
_____________________________________
Oliver Sparrow
Tel: UK (0)20 7736 9716
www.chforum.org
www.treknepal.org
www.datafreeze.com
_______________________________________________
the OrchidGuide Digest (OGD)
[email protected]
http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
_______________________________________________
the OrchidGuide Digest (OGD)
[email protected]
http://orchidguide.com/mailman/listinfo/orchids_orchidguide.com
