Strange how the world goes around. I
heard this very same fascinating story of sex and deception amongst wasps and
orchids while chatting with Graham Brown here in Darwin last weekend.
Anyway, Graham has asked me to pass on,
regarding Geoffrey’s photos, that “the wasp is almost
certainly a species of the 'Lophocheilus' obscurus complex.”
Cheers
John Rawsthorne
From:
pete cranston [
Sent: Thursday, 24 March 2011
11:24 AM
To: Geoffrey Dabb;
Subject: [canberrabirds]
Entomology Corner - bugs and sex
The insect is indeed a wasp, same order as the bees (Hymenoptera). This
one is a male thynnine wasp - it is winged which distinguishes from its
flightless female. These wasps are stars of the screen, with extraordinary
footage from Western Australia in the BBC / Attenborough series 'Life in the
Undergrowth'. They are involved in a sexual deception system involving
orchids that are chemical mimics of the female wasps' pheromone lures. Simply
put, the wingless female adult thynnine climbs to the top of a plant (often a
grass) and emits her perfume to lure in male suitors. After a brief courtship
she allows a male to take her on a nuptial flight during which he mates with
her (all captured by BBC film unit). But into this straightforward system come
many different orchids, which have attained a perfect or close match to the
female thynnine's fragrance - hence luring males deceived into expecting
a receptive female. The orchids' shapes and colours are passable imitations of
a female perched on the top of a grass blade - certainly good enough for the
witless male 'victim' . He attempts to copulate with the orchid's deceptive
model, whereupon he receives an orchid pollenium stuck on his rear. Not being
too bright, the male repeats the sterile performance (termed
'pseudo-copulation') again and again, ensuring at least the orchid is
pollinated.
The system is complex - there are many orchids and many species of thynnines
(especially in Western Australia, but also locally in ACT), and there is
evidence of quite tight association between the component species. And now the
male thynnine has another problem - scientists have succeeded in synthesising
the chemicals in the phermone mixes, and can lure in the males for study.
Amongst those researching this system is Rod Peakall at the Australian National
University.
While teaching students in California over the past decade, this tale, and the
footage from the BBC would stimulate even the doziest students.
Pete Cranston
At 11:38 24/03/2011, Geoffrey Dabb wrote:
You may be right
Paul. Species? (Note patterned wings and strongly segmented
abdomen)
-----Original Message-----
From: Paul T.
Sent: Thursday, 24 March 2011 10:14 AM
To:
Subject: Entomology Corner
And then the next frame has the bird on the left answering...... "No,
that is the even rarer Rainbow Wasp-eater!" <grin>
Cheers.
Paul T.
Higgins, ACT.
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