http://www.collembola.org/publicat/courtshp.htm
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Last updated on
2017.07.02
by Frans Janssens
Frans Janssens,
Department of Biology, University of Antwerp, Antwerp, B-2020, Belgium
Marie Louise Huskens,
Opitterkiezel 223 bus 0.1, B-3960, Opitter, Belgium
Abstract
During the courtship ritual of Deuterosminthurus pallipes,
the male guides the female
towards the spermatophore, by producing a
stretched protein thread of spermcapsule material. While she is consuming
the protein thread, she is moving forward over the spermatophore which she will
take up with her gonopore, eventually.
Introduction
Contrary to Sminthurididae, in Bourletiellidae there is no distinct
sexual dimorphism (Betsch, 1980:113).
Sperm transfer, in Bourletiellidae, requires a succession of interactions
between the two sexes (Betsch, 1980:110), hence the courtship ritual.
In Deuterosminthurus, the male takes the active role in the ritual
(Betsch, 1980:116).
While the ritual has been documented in detail by Bretfeld (1971:147-150),
in this contribution we will provide in addition a clarification of the way
the male of Deuterosminthurus guides the female to take up the spermatophore.
Material and methods
Specimens of Deuterosminthurus pallipes forma repandus
were collected from the garden of the second author in Opitter,
Limburg, Belgium.
The specimens were collected with their habitat material.
Observations were performed indoors on a staged set-up.
Photographs were made using a digital reflex camera Canon EOS 80D.
A Canon MP-E 65mm lens was mounted on the camera using a
set of Kenko extension tubes (12mm + 20mm + 36mm).
Illumination was provided by a Canon Macro Ring Lite MR-14EX
and a Falcon Eyes SLP-120LTV LED lamp.
Results
The indoors stage was set-up and after an hour the
specimens got settled and started the courtship ritual activities.
The courtship ritual:
1. The male follows and circumvents the female, running fast
and vibrating with his antennae (Bretfeld 1969:425).
2. After a preliminar contact between male and female,
the male puts himself in a head to head position with the female
(Bretfeld 1969:425;1971:147; Betsch, 1980:116).
The male and female fold back their antennae (Bretfeld, 1971:148) (Fig.Dp4).
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Fig.Dp4. Deuterosminthurus pallipes f. repandus.
Male and female in head to head position
Huskens, M.L. © 2017.06.20
3. The male places his antennae on the antennae of the female
and touches the backfolded antennae
of the female with the 4th antennal segment while vibrating his antennae
(modified after Bretfeld, 1971:147; Betsch, 1980:113,116).
An unreceptive female will interrupt the ritual and will run away,
while a receptive female will stay in place
(modified after Betsch, 1980:116).
4. The male may move backward and forward several times,
releasing and rejoining the head of the female,
while the female follows his movements,
and while the male continues 'striking' the female with his vibrating antennae
(modified after Bretfeld, 1969:425;1971:147).
The more rapid vibration indicates that both sexes are getting more excited.
(modified after Betsch, 1980:116).
5. The male seems to hesitate whether or not to turn around,
making a kind of 'false move',
and he bends one of his antennae (the one he will use later, in step 6)
(pers. obs.).
Then the male turns around (Fig.Dp3),
and deposits a spermdrop on a short stalk (Fig.Dp1) in front of the female
(modified after Bretfeld, 1969:425;1971:147; Betsch, 1980:117).
In contrast to D. pallipes, in the closely related D. bicinctus
the male may turn around several times in front of
the female before depositing a spermatophore (Bretfeld, 1969:426).
This different kind of behaviour may be used to distinguish
D. pallipes forma repandus from
D. bicinctus forma flavus
based on their courtship ritual.
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Fig.Dp3. Deuterosminthurus pallipes f. repandus.
Male turns around to deposit a spermatophore in front of female
Huskens, M.L. © 2017.06.20
6. The male turns around again
and establishes contact with the spermatophore using his antenna
(modified after Betsch, 1980:117),
(distal end of 3rd antennal segment (Bretfeld, 1971:147))
and mouth (Bretfeld, 1969:426)
or with his frontleg (Bretfeld 1970).
In our observations, contrary to Bretfeld (1971:147), the contact was made
with the basal end of the 4th antennal segment (Fig.Dp0,Dp1,Dp2).
7. The female eats/drinks a part of the spermdrop (Fig.Dp1)
and advances over the spermatophore to absorb the sperm by her gonopore
(modified after Bretfeld, 1971:147; Betsch, 1980:117).
8. The male moves backwards in concert with the female that moves forwards
to guide her over the spermatophore (Bretfeld 1970)
(modified after Betsch, 1980:117).
9. The female eats the remains of the spermatophore,
while the male cleans his antenna (Bretfeld, 1969:426;1971:147).
Then the sexes separate.
Discussion
Neither Bretfeld (1969,1971) nor Betsch (1980) specified how the male guides the
female over the spermatophore.
At first sight, it seems that the male is trying to 'pull' the female over
the spermatohore
using a stretched thread of spermcapsule material (pers. obs) (Fig.Dp0,Dp2).
The thread has been formed by dipping the base of the 4th antennal segment
into the freshly deposited spermdropcapsule of the spermatophore.
The stretched protein thread is attached at the apex of the spermdrop (Fig.Dp1).
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Fig.Dp0. Deuterosminthurus pallipes f. repandus.
Male 'pulling' female by a thread (*) of spermcapsule (S) material
Huskens, M.L. © 2017.06.20
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Fig.Dp1. Deuterosminthurus pallipes f. repandus.
Male 'pulling' female by a thread (> <) of spermcapsule material
Huskens, M.L. © 2017.06.23
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Fig.Dp2. Deuterosminthurus pallipes f. repandus.
Male 'pulling' female by a thread of spermcapsule material
Huskens, M.L. © 2017.06.20
If the female continues eating the spermdrop (Fig.Dp1), reproduction fails.
If she continues eating the thread (Fig.Dp0) that, originally, is connected
to the spermdrop, reproduction may succeed.
Conclusion
The male of Deuterosminthurus pallipes forma repandus guides the female in the
courtship ritual towards the spermatophore, by producing a
stretched thread of spermcapsule protein. While she is consuming
the protein thread, he is moving backwards, pulling as such at the thread,
she is moving forward over the spermatophore, which she will
take up with her gonopore, eventually.
Bibliography
