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Hi Steve,
That's very interesting! I've often wondered how it might be possible
for parasitic wasps of this sort to detect their prey. This would be
very interesting for someone to follow up. I was looking at some
braconids and ichneumonids that parasitize bark- and wood-boring
beetle and it seemed to me that they also have fairly robust
metathoracic tibiae (none of them so extremely enlarged as in
Pelecinus polyturator).
I've watched these wasps at work on fallen logs. I expect that they
must also be using such subgenual organs to detect the larvae of these
phloeophagous beetle larvae from the vibrations that they cause in the
wood as they gnaw their way through cambium. It would be interesting
to experiment and determine how specific a vibratory signal is
required to initiate ovapositing behavior. I wonder if anyone has done
such research?
Thanks for this!
Chris
On 8-Aug-11, at 12:59 AM, Stephen R. Shaw wrote:
> This struck a chord in part because we get them occasionally at this
> time of year too, nearer the end of August on what's left of our
> lawn in Halifax.
>
> Another interesting thing about these female P. polyturator is the
> extreme enlargement of the tibia of the two long hind legs. The
> proximal end of this part of each of the 6 legs in most insects
> contains a multi-sensor ground vibration detector called the
> subgenual organ, SGO ('below-the-knee organ'). It's sensitive to
> displacements down to about 1 nanometer in a cockroach (with its 25
> sensors), about the same as the displacement at the basilar membrane
> inside the cochlea of the ear at absolute sound threshold at our
> best frequency; the threshold there is probably limited by Brownian
> motion of particles in the fluid bombarding the membrane.
>
> It's possible that the extreme enlargement in the metathoracic
> tibiae of Pelecinus represents some even greater enhancement,
> perhaps in low-frequency tuning or averaging using its SGO. That
> could help the wasp detect the specific vibrations produced by its
> June Bug larval targets that apparently live several centimeters
> underground. Years ago I made a couple of tibial preparations and
> sent them to a German academic who had expressed an interest in
> doing the necessary electron-microscopy, but as far as I know this
> was a minor wasted effort as he never followed through on it.
> Interests diverge and progress, so such cul-de-sacs are not unknown
> in science.
>
> Steve, Halifax
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Quoting Christopher Majka <c.majka@ns.sympatico.ca>:
>> Hi Jim,
>> They are a fabulous beast. It is certainly Pelecinus polyturator,
>> since this is a mono-specific genus. Males are occasionally found
>> in southern latitudes, but in the Maritimes it is an exclusively
>> parthenogenically-reproducing female species.
>>
>> Cheers,
>>
>> Chris
>>
>> On 7-Aug-11, at 8:09 PM, James W. Wolford wrote:
>>
>>> AUGUST 5 & 6, 2011 - Pat & I drove to Lunenburg for 2 of the 3.5-
>>> day Folk Harbour Festival.
>>>
>>> On our first afternoon there, on the lawn behind the Lincoln
>>> House ex-B&B, we found a very-long-bodied female Pelecinidae
>>> black wasp that hunts and preys on grubs/larvae of May beetles or
>>> June beetles under the sod. Very probably this was a Pelecinus
>>> polyturator , which exists as nearly all females in most or all
>>> areas of occurrence. The species has a wide range in North
>>> America and apparently exists under several different names.
>>> Since they are nearly all females, the eggs they lay, one at a
>>> time on each beetle larva found, must be parthenogenic, i.e. not
>>> needing fertilization, and probably formed by a modified form of
>>> meiosis.
>>>
>>> Cheers from Jim in Wolfville.
>>
>> Christopher Majka <c.majka@ns.sympatico.ca> | Halifax, Nova
>> Scotia, Canada
>>
>
Christopher Majka <c.majka@ns.sympatico.ca> | Halifax, Nova Scotia,
Canada
* Research Associate: Nova Scotia Museum | http://museum.gov.ns.ca/mnh/research-asfr.htm
* Review Editor: The Coleopterists Bulletin | http://www.coleopsoc.org/
* Subject Editor: ZooKeys | http://pensoftonline.net/zookeys/index.php/journal/index
* Review Editor: Zootaxa | http://www.mapress.com/zootaxa/taxa/Coleoptera.html
* Associate Editor: Journal of the Acadian Entomological Society | http://www.acadianes.org/journal.html
* Editor: Atlantic Canada Coleoptera | http://www.chebucto.ns.ca/Environment/NHR/PDF/index.html
* Editor: Bugguide, Coleoptera http://bugguide.net
Whenever I hear of the capture of rare beetles, I feel like an old war-
horse at the sound of a trumpet. - Charles Darwin
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<html><body style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space; ">Hi =
Steve,<div><br></div><div>That's very interesting! I've often wondered =
how it might be possible for parasitic wasps of this sort to detect =
their prey. This would be very interesting for someone to follow up. I =
was looking at some braconids and ichneumonids that parasitize bark- and =
wood-boring beetle and it seemed to me that they also have fairly =
robust metathoracic tibiae (none of them so extremely enlarged as =
in <i>Pelecinus =
polyturator</i>). </div><div><br></div><div>I've watched these =
wasps at work on fallen logs. I expect that they must also be using =
such subgenual organs to detect the larvae of these phloeophagous =
beetle larvae from the vibrations that they cause in the wood as they =
gnaw their way through cambium. It would be interesting to experiment =
and determine how specific a vibratory signal is required to initiate =
ovapositing behavior. I wonder if anyone has done such =
research?</div><div><br></div><div>Thanks for =
this!</div><div><br></div><div>Chris</div><div><br><div><div>On =
8-Aug-11, at 12:59 AM, Stephen R. Shaw wrote:</div><br =
class=3D"Apple-interchange-newline"><blockquote type=3D"cite"><div>This =
struck a chord in part because we get them occasionally at this time of =
year too, nearer the end of August on what's left of our lawn in =
Halifax.<br><br>Another interesting thing about these female P. =
polyturator is the extreme enlargement of the tibia of the two long hind =
legs. The proximal end of this part of each of the 6 legs in most =
insects contains a multi-sensor ground vibration detector called the =
subgenual organ, SGO ('below-the-knee organ'). It's sensitive to =
displacements down to about 1 nanometer in a cockroach (with its 25 =
sensors), about the same as the displacement at the basilar membrane =
inside the cochlea of the ear at absolute sound threshold at our best =
frequency; the threshold there is probably limited by Brownian motion of =
particles in the fluid bombarding the membrane.<br><br>It's possible =
that the extreme enlargement in the metathoracic tibiae of Pelecinus =
represents some even greater enhancement, perhaps in low-frequency =
tuning or averaging using its SGO. That could help the wasp detect the =
specific vibrations produced by its June Bug larval targets that =
apparently live several centimeters underground. Years ago I made =
a couple of tibial preparations and sent them to a German academic who =
had expressed an interest in doing the necessary electron-microscopy, =
but as far as I know this was a minor wasted effort as he never followed =
through on it. Interests diverge and progress, so such cul-de-sacs =
are not unknown in science.<br><br>Steve, Halifax<br> =
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~<br>Quoting =
Christopher Majka <<a =
href=3D"mailto:c.majka@ns.sympatico.ca">c.majka@ns.sympatico.ca</a>>:<b=
r><blockquote type=3D"cite">Hi Jim,<br></blockquote><blockquote =
type=3D"cite">They are a fabulous beast. It is certainly Pelecinus =
polyturator, since this is a mono-specific genus. Males are =
occasionally found in southern latitudes, but in the Maritimes it =
is an exclusively parthenogenically-reproducing female =
species.<br></blockquote><blockquote =
type=3D"cite"><br></blockquote><blockquote =
type=3D"cite">Cheers,<br></blockquote><blockquote =
type=3D"cite"><br></blockquote><blockquote =
type=3D"cite">Chris<br></blockquote><blockquote =
type=3D"cite"><br></blockquote><blockquote type=3D"cite">On 7-Aug-11, at =
8:09 PM, James W. Wolford wrote:<br></blockquote><blockquote =
type=3D"cite"><br></blockquote><blockquote type=3D"cite"><blockquote =
type=3D"cite">AUGUST 5 & 6, 2011 - Pat & I drove to Lunenburg =
for 2 of the 3.5-day Folk Harbour =
Festival.<br></blockquote></blockquote><blockquote =
type=3D"cite"><blockquote =
type=3D"cite"><br></blockquote></blockquote><blockquote =
type=3D"cite"><blockquote type=3D"cite">On our first afternoon there, on =
the lawn behind the Lincoln House ex-B&B, we found a =
very-long-bodied female Pelecinidae black wasp that hunts and =
preys on grubs/larvae of May beetles or June beetles under the =
sod. Very probably this was a Pelecinus polyturator , which =
exists as nearly all females in most or all areas of occurrence. =
The species has a wide range in North America and =
apparently exists under several different names. Since they =
are nearly all females, the eggs they lay, one at a time on each =
beetle larva found, must be parthenogenic, i.e. not needing =
fertilization, and probably formed by a modified form of =
meiosis.<br></blockquote></blockquote><blockquote =
type=3D"cite"><blockquote =
type=3D"cite"><br></blockquote></blockquote><blockquote =
type=3D"cite"><blockquote type=3D"cite">Cheers from Jim in =
Wolfville.<br></blockquote></blockquote><blockquote =
type=3D"cite"><br></blockquote><blockquote type=3D"cite">Christopher =
Majka <<a =
href=3D"mailto:c.majka@ns.sympatico.ca">c.majka@ns.sympatico.ca</a>> =
| Halifax, Nova Scotia, Canada<br></blockquote><blockquote =
type=3D"cite"><br></blockquote><br></div></blockquote></div><br></div><br>=
<br><div apple-content-edited=3D"true"> <span class=3D"Apple-style-span" =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
'Times New Roman'; font-style: normal; font-variant: normal; =
font-weight: normal; letter-spacing: normal; line-height: normal; =
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style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space; "><span class=3D"Apple-style-span" =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
'Times New Roman'; font-style: normal; font-variant: normal; =
font-weight: normal; letter-spacing: normal; line-height: normal; =
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-webkit-border-vertical-spacing: 0px; =
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auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div =
style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space; "><span class=3D"Apple-style-span" =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
'Times New Roman'; font-style: normal; font-variant: normal; =
font-weight: normal; letter-spacing: normal; line-height: normal; =
orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; =
widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; =
-webkit-border-vertical-spacing: 0px; =
-webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: =
auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div =
style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space; "><span class=3D"Apple-style-span" =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
'Times New Roman'; font-style: normal; font-variant: normal; =
font-weight: normal; letter-spacing: normal; line-height: normal; =
orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; =
widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; =
-webkit-border-vertical-spacing: 0px; =
-webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: =
auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div =
style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space; "><span class=3D"Apple-style-span" =
style=3D"border-collapse: separate; color: rgb(0, 0, 0); font-family: =
'Times New Roman'; font-style: normal; font-variant: normal; =
font-weight: normal; letter-spacing: normal; line-height: normal; =
orphans: 2; text-indent: 0px; text-transform: none; white-space: normal; =
widows: 2; word-spacing: 0px; -webkit-border-horizontal-spacing: 0px; =
-webkit-border-vertical-spacing: 0px; =
-webkit-text-decorations-in-effect: none; -webkit-text-size-adjust: =
auto; -webkit-text-stroke-width: 0px; font-size: medium; "><div =
style=3D"word-wrap: break-word; -webkit-nbsp-mode: space; =
-webkit-line-break: after-white-space; =
"><div><div><div><div><div><div><div><div><font class=3D"Apple-style-span"=
size=3D"3"><span class=3D"Apple-style-span" style=3D"font-size: 12px; =
">Christopher Majka <<a =
href=3D"mailto:c.majka@ns.sympatico.ca">c.majka@ns.sympatico.ca</a>> =
| Halifax, Nova Scotia, Canada</span></font></div><div><font =
class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" =
style=3D"font-size: 12px; "><br></span></font></div><div><font =
class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" =
style=3D"font-size: 12px; ">* Research Associate: Nova Scotia Museum =
| <a =
href=3D"http://museum.gov.ns.ca/mnh/research-asfr.htm">http://museum.gov.n=
s.ca/mnh/research-asfr.htm</a></span></font></div><div><font =
class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" =
style=3D"font-size: 12px; ">* Review Editor: The Coleopterists Bulletin =
| <a =
href=3D"http://www.coleopsoc.org/">http://www.coleopsoc.org/</a></span></f=
ont></div><div><font class=3D"Apple-style-span" size=3D"3"><span =
class=3D"Apple-style-span" style=3D"font-size: 12px; ">* Subject Editor: =
ZooKeys | <a =
href=3D"http://pensoftonline.net/zookeys/index.php/journal/index">http://p=
ensoftonline.net/zookeys/index.php/journal/index</a></span></font></div><d=
iv><font class=3D"Apple-style-span" size=3D"3"><span =
class=3D"Apple-style-span" style=3D"font-size: 12px; ">* Review Editor: =
Zootaxa | <a =
href=3D"http://www.mapress.com/zootaxa/taxa/Coleoptera.html">http://www.ma=
press.com/zootaxa/taxa/Coleoptera.html</a></span></font></div><div><font =
class=3D"Apple-style-span" size=3D"3"><span class=3D"Apple-style-span" =
style=3D"font-size: 12px; ">* Associate Editor: Journal of the Acadian =
Entomological Society | <a =
href=3D"http://www.acadianes.org/journal.html">http://www.acadianes.org/jo=
urnal.html</a></span></font></div><div><font class=3D"Apple-style-span" =
size=3D"3"><span class=3D"Apple-style-span" style=3D"font-size: 12px; =
">* Editor: Atlantic Canada Coleoptera | <a =
href=3D"http://www.chebucto.ns.ca/Environment/NHR/PDF/index.html">http://w=
ww.chebucto.ns.ca/Environment/NHR/PDF/index.html</a></span></font></div><d=
iv><font class=3D"Apple-style-span" size=3D"3"><span =
class=3D"Apple-style-span" style=3D"font-size: 12px; ">* Editor: =
Bugguide, Coleoptera <a =
href=3D"http://bugguide.net">http://bugguide.net</a></span></font></div><d=
iv><font class=3D"Apple-style-span" size=3D"3"><span =
class=3D"Apple-style-span" style=3D"font-size: 12px; =
"><br></span></font></div><div><i><font class=3D"Apple-style-span" =
size=3D"3"><span class=3D"Apple-style-span" style=3D"font-size: 12px; =
">Whenever I hear of the capture of rare beetles, I feel like an =
old war-horse at the sound of a trumpet.</span></font></i><span =
class=3D"Apple-converted-space"><font class=3D"Apple-style-span" =
size=3D"3"><span class=3D"Apple-style-span" style=3D"font-size: 12px; =
"> </span></font></span><font class=3D"Apple-style-span" =
size=3D"3"><span class=3D"Apple-style-span" style=3D"font-size: 12px; =
">- =
Charles Darwin</span></font></div></div></div></div></div></div></div=
></div></div></span></div></span></div></span></div></span></div></span> =
</div><br></body></html>=
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