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 From: kegarvey at ucdavis.edu
To: Ladadams at aol.com
Sent: 10/13/2011 10:42:07  A.M. Pacific Daylight Time
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This just  in—should be of interest. 
_http://www.eurekalert.org/pub_releases/2011-10/miot-mrs101211.php_ 
(http://www.eurekalert.org/pub_releases/2011-10/miot-mrs101211.php)  
Contact: Caroline McCall
_cmccall5 at mit.edu_ (mailto:cmccall5 at mit.edu) 
_Massachusetts Institute of  Technology_ (http://web.mit.edu/newsoffice)   
MIT research: Sugar high for bees
Bees, and similar nectar feeders, get sweeter juice with dipping  tongues
CAMBRIDGE, Mass. -- A field of flowers may seem innocuous — but for the  
birds and bees that depend on it for sustenance, that floral landscape can be  
a battlefield mined with predators and competitors. The more efficient a  
pollinator is in feeding, the less chance it has of becoming food  itself. 
Now mathematicians at MIT have found that efficient feeding depends on how  
sugary a flower's nectar is, and whether an animal dips or sucks the nectar 
 out. The researchers found that animals such as bees, which probe with 
their  tongues, are "viscous dippers," and are most efficient when feeding on 
more  sugary, or viscous, nectar. Suction feeders, such as birds and 
butterflies  that draw nectar up through tubes, do their best when sucking up 
thinner, less  sugary nectar. 
The difference, says John Bush, a professor of applied mathematics, may  
point to a co-evolutionary process between flowers and their  pollinators. 
"Do the flowers want a certain type of bug or bird to pollinate them? And  
are they offering up the nectar of their preferred pollinator?" Bush asks.  
"It's an interesting question whether there's a correlation between the  
morphology of the plant and the morphology of the insect." 
The researchers published their results in a recent issue of the  
Proceedings of the National Academy of Sciences. 
While Bush is not a biologist, he says curiosities in nature, including  
nectar feeding, pose fascinating challenges for mathematicians. As he sees it, 
 nectar feeding is a classic example of optimization in nature: The sweeter 
the  nectar, the more energy it delivers, but the more energy it takes to  
transport. The optimal sugar concentration shifts according to how the fluid 
 is taken up. 
As a large-scale analogy, Bush says it's more efficient to suck up sugar  
water than molasses through a straw. Conversely, it's more effective to dip a 
 spoon in and out of honey versus juice. There's an ideal viscosity for a 
given  uptake mechanism, an optimization puzzle that Bush says is tailored 
for  mathematics. 
The birds and the bees 
To get at this puzzle, Bush and his colleagues analyzed data from previous  
papers on nectar-feeding species, which include bats, birds, bees and  
butterflies. Most papers described two kinds of nectar-drinking mechanisms:  
active suction, whereby butterflies and moths suck nectar up through long,  
narrow tubes, or probosci; and passive suction, in which hummingbirds and  
sunbirds draw nectar up in their tongues via capillary action. 
The team compiled the papers' data and found that both groups of suction  
feeders were most efficient at taking up the same concentration — 33 percent —
  of sugar in nectar. 
The researchers did the same for viscous dippers: species such as ants,  
bees and bats, which extract nectar by dipping their tongues in and out of  
flowers. For these dippers, they found the ideal sugar concentration was 52  
percent, demonstrating a preference among these species for nectar that's 
much  more viscous, and sweeter, than their sucking counterparts. 
Going a step further, Wonjung Kim, a graduate student of mechanical  
engineering and lead author of the paper, took an experimental approach,  studying 
live bees in the lab. Kim collected several bees from around MIT and  kept 
them in a box lined with paper towels soaked in a sugar solution. Kim  
filmed the bees with a high-speed camera, confirming that the insects did  indeed 
dip their tongues in the syrupy surface. 
Going with the flow 
Bush and Kim plan to examine the ways in which other species drink, in  
order to model more small-scale fluid dynamics. One target, Bush says, is a  
certain desert lizard that "drinks" through its skin. The lizard simply has to 
 step in a puddle of water, and an intricate system of cracks in its skin 
soaks  up moisture — a useful trait in extremely dry environments. 
"People are now interested in moving around small volumes of fluid for  
microfluidic applications," Bush says. "It's clear that nature has been  
solving these problems for millions of years. Animals have learned how to  
efficiently navigate, transport and manipulate water. So there's clearly much  to 
learn from them in terms of mechanisms." 
 
Kathy  Keatley Garvey
Communications Specialist
Department of Entomology
372  Briggs Hall
One Shields Ave.
University of California, Davis
Davis,  CA 95616
Phone: (530) 754-6894
Fax: (530) 752-1537
_kegarvey at ucdavis.edu_ (mailto:kegarvey at ucdavis.edu)  
UC  Davis Department of Entomology website:
_http://entomology.ucdavis.edu/home.cfm_ 
(http://entomology.ucdavis.edu/home.cfm) 
Harry  H. Laidlaw Jr. Honey Bee Research Facility website:
_http://beebiology.ucdavis.edu_ (http://beebiology.ucdavis.edu/) 
UC  Agriculture and Natural Resources website:
_http://ucanr.org/index.cfm_ (http://ucanr.org/index.cfm) 
Bug Squad  Blog
_http://ucanr.org/blogs/bugsquad/_ (http://ucanr.org/blogs/bugsquad/) 
Flickr  Photos 
_http://www.flickr.com/photos/pho-tog/_ 
(http://www.flickr.com/photos/pho-tog/) 


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