[Odonata-l] Involuntary Mating

[Dennis Paulson]

Paul,

I have often seen male odonates swinging up females like that, both  
at rest and at flight, usually with the female's cooperation by  
bending her abdomen. I suppose on occasion she connects with the  
male's second segment even if she wasn't inclined to mate, and that's  
enough to stimulate copulation. It would seem that if they were the  
same species, she would be inclined to mate just because it will  
quickly free her to continue laying her eggs. I have also seen  
females of a number of species actively trying to avoid males as they  
oviposited but then going into copulation once they were seized, and  
this has been reported for a lot of species, I think. When the male  
and female are different species, I assume the female is much less  
inclined to cooperate.

I have seen Aeshna flying in tandem with the female dangling down on  
numerous occasions, sometimes seemingly struggling. On some of these  
occasions I was fairly sure the two were different species. A few of  
these speculations were confirmed by catching the pair. I found a  
heterospecific pair (male Rhionaeschna multicolor, female Aeshna  
palmata) in tandem very freshly dead on the water once and assumed  
they had splashed down while struggling and were unable to fly again  
because they were hooked together. The male grip on the female's head  
was sufficiently tenacious that it took a bit of handling to dislodge  
it. From some experiments I performed with tethered females, it  
seemed that a male Aeshna would try to grab any female of any species  
he encountered ovipositing. The weirdest pair I saw was a male  
Rhionaeschna multicolor dragging a conspicuously larger male Aeshna  
eremita in this way. Those males ought to be more discriminating!

Dennis

On Sep 1, 2008, at 11:40 AM, Paul Brunelle wrote:

> Hello All;
> 	Thanks to those who responded to the Lestes ovipositing question.
> 	Another interesting thing that I saw for the first time this year  
> was an involuntary (on the female's part) mating.
> 	I had always assumed that while the male might grasp a female, she  
> alone decided whether to mate by bending her abdomen forward and up  
> to engage his secondary genitalia. I have many times seen a male  
> with a female in tow but hanging vertically zooming around  
> apparently waiting for her to engage - particularly in Aeshna.
> 	I was observing some Nannothemis bella in July and saw a male  
> capture an ovipositing female and land on an emergent plant - the  
> female hung straight down and apparently refused to engage. The  
> male flew several times to other perches without persuading her.  
> Finally he flew a few inches up from the water surface and flipped  
> the both of them (I think forward), till at the end of the third  
> flip she was engaged in cop. This was the kind of flip I often see  
> after dunking, and which I had heard was done to force water  
> droplets into the mouth.
> 	My distinct impression was that this female was taken into cop  
> against her will.
> 	Anyone else seen this?
> 	Regards,
> 	Paul

-----
Dennis Paulson
1724 NE 98 St.
Seattle, WA 98115
206-528-1382
dennispaulson at comcast.net



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