Pollination Vectors

German Roitman ggroiti@agro.uba.ar
Mon, 12 May 2008 16:34:36 PDT
Dear Jim:

I have been searching in some databases of 
pollination and the info available refers that 
Trillium is self sterile (it need the activity of 
pollinator for seed set) and most species are 
pollinated by bumblebees, flies, ants and 
beetles. The fly you have observed is probably a 
Syrphid fly not a Drosophila, i guess. Syrphid 
flies use to eat pollen and pollinate as well.

You can check this publication for more information and references:

Tammy L. Sage, Steven R. Griffin, Vincenza 
Pontieri, Peter Drobac, William W. Cole and 
Spencer C. H. Barrett  2001. Stigmatic 
Self-Incompatibility and Mating Patterns in 
Trillium grandiflorum and Trillium erectum(Melanthiaceae)
Annals of Botany 88: 829-841

Post-pollination processes governing mating 
patterns in Trillium, a well-known genus of 
insect-pollinated woodland herbs, are poorly 
understood. Mechanisms influencing outcrossing 
were investigated in T. grandiflorum and T. 
erectum, two widespread species native to eastern 
North America. In southern Ontario, Canada, the 
two species are often sympatric; they flower in 
early May, and are pollinated by different 
assemblages of insects. Controlled cross- and 
self-pollinations and structural observations of 
pollen germination and pollen tube growth were 
conducted to determine whether the two species 
possess a self-incompatibility (SI) system and, 
if so, the specific site(s) of self-rejection. 
Controlled pollinations indicated that both 
species set significantly more seeds from 
cross-pollination than self-pollination, 
implicating the action of SI. This was confirmed 
by structural studies which demonstrated that 
self-recognition and rejection reactions occurred 
on dry-type stigmatic papillae. Observations of 
pollen hydration revealed that self-rejection was 
rapid, being initiated within 10 min of 
pollination and prior to pollen tube emergence. 
Final self-rejection resulted in failure of 
pollen tube growth at the base of stigmatic 
papillae. SI was expressed more weakly in T. 
erectum and thereby resulted in considerable 
self-seed set in some individuals . Estimates of 
outcrossing rates using allozyme markers 
indicated that T. erectum displayed a 
mixed-mating system whereas T. grandiflorum was 
more highly outcrossed. Structural studies of 
pollen traits indicated that the two species 
differed with respect to the size of grains and 
their aggregation with implications for pollen 
dispersal and mating. The ecological and 
evolutionary implications of the variable 
expression of SI in Trillium are discussed.


In your case if the 2 species of Trillium has 
diferent pollen shape (color, size, etc), perhaps 
you can capture the flies using a dry method so 
pollen is not washed and then extract the pollen 
from the bodie of the flie and observe it using a 
microscope, in that way you can see if the flies 
visit the 2 species or only one of them.

Hope this help

Best wishes


At 11:19 11/05/2008, you wrote:
>Hi Kelly,
>I'm just referring to anything that transports pollen from one flower to
>another in a manner that results in pollination of the recipient flower, so
>I use "vector" in the broadest sense.  It had not occurred to me before
>that there might be a methodology involved in establishing that a
>particular bug was a true natural pollinator of a given plant species.
>Jim Shields
>At 09:06 AM 5/11/2008 -0500, you wrote:
> >Hi, Jim. I don't have an answer. I would ask are meaning "pollinator"
> >and not "pollination vector", unless you are talking about disease carriers?
> >
> >Mr. Kelly M. Irvin
> >10850 Hodge Ln
> >Gravette, AR 72736
> >USA
> >
> >479-787-9958
> >USDA Cold Hardiness Zone 6a/b
> >
> >http://www.irvincentral.com/
> >
> >_______________________________________________
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>Jim Shields             USDA Zone 5             Shields Gardens, Ltd.
>P.O. Box 92              WWW:    http://www.shieldsgardens.com/
>Westfield, Indiana 46074, USA
>Tel. ++1-317-867-3344     or      toll-free 1-866-449-3344 in USA
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