[Pollinator] Pollinator Manipulators

[Ladadams at aol.com]

Pollinator manipulators 
By _Rachel  Ehrenberg_ 
(http://www.sciencenews.org/view/authored/id/62/name/Rachel_Ehrenberg) 
Web edition : Thursday, August 28th,  2008
    *    (http://www.sciencenews.org/index/generic)   
(http://www.sciencenews.org/index/generic)  Text Size 
Plant laces nectar with poison to better  control visitors
 
 
(http://www.sciencenews.org/view/access/id/36009/name/re_hummingbird_tobacco_web.jpg)   
The wild tobacco  lures pollinators, such as hummingbirds, with a suite of 
floral traits that  includes chemical attractants. The plants' nectar is also 
laced with poisonous  nicotine that prevents visitors from loitering at a single 
flower for too long,  a new study finds. _Full  Story_ 
(http://www.sciencenews.org/view/generic/id/36010/title/Pollinator_manipulators) D. Kessler

Scientists investigating a desert weed have uncovered a high-stakes world of  
gambling, sex and poison-laced cocktails. The study, appearing in the Aug. 29 
 Science, details how a species of wild tobacco cunningly manipulates  its 
pollinators for the sake of the plant’s children.  
The research, which was done with “surgical  precision,” demonstrates that 
the plants take an active role in their fate,  comments Rob Raguso of Cornell 
University. “They are behaving — they are  not passive players,” he says. “
These plants are calling the shots.” 
It shouldn’t come as a surprise that plants, like  other organisms, make an 
effort to “outcross” — mixing their genes with an  unrelated mate — to get 
variation that could improve the odds that their young  will survive. But for 
the most part, plants can’t move. So they must manipulate  the postmen, the 
pollinators that deliver sperm and take it away, says Ian  Baldwin, who did the 
new work with colleagues Danny Kessler and Klaus Gase.  Hummingbirds and hawk 
moths play this role for the wild tobacco Nicotiana  attenuata.  
Previous work by Baldwin, of the Max  Planck Institute for Chemical Ecology 
in Jena, Germany, revealed that benzyl acetone  is the dominant pollinator 
attractant in the wild tobacco’s flowers. The  researchers also learned that the 
plant spikes its nectar with nicotine, perhaps  as a poisonous deterrent to 
flower-eating insects or nectar robbers.  
To investigate the influence of floral chemistry,  the researchers created 
plants that did not produce either benzyl acetone or  nicotine, or both. In 
greenhouse and field experiments, the scientists were  surprised to find that not 
only did nicotine deter nectar robbers and plant  nibblers, but the right dose 
prevented pollinators from lingering too long at  any one flower, increasing 
the number of flowers visited.  
“It’s not just a matter of the flowers saying  ‘Hello, we are here, would 
you like a soft drink?’ ” says Baldwin. “It is a  pretty conniving soft drink.”
  
Plants with the right cocktail had the biggest  seed capsules as well, 
directly linking floral chemistry to fitness, the  researchers report.  
The little wild tobacco is an annual, the  researchers note; it has one 
season to grow, make seeds and die. If all else  fails, the plant can successfully 
self-pollinate. But that doesn’t keep it from  hedging its bets.  
“It’s a good investor,” Raguso says. “It has a  well-diversified portfolio.”
 





















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Laurie Davies Adams
Executive  Director
Pollinator Partnership 
423 Washington Street, 5th  floor
San Francisco, CA  94111
415-362-1137
LDA at pollinator.org

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