Captain Video

Rudy Benavides rbenavid at hotmail.com
Fri Jun 22 10:20:17 EDT 2001


Patrick wrote...
>Michael,
>
>You ask why butterflies do not visit members of the rose family as much as
>do bees.Rosaceae have lots of pollen-bearing anthers which surely attract
>bees.... Ultimately, rosaceous plants may have evolved to be less
>attractive to butterflies if they are 1) less useful than the
>pollen-gathering bees and 2) largely parasitic on open flowers since they
>don't have to stick their faces into the anthers to get at nectar.

I guess another way of saying this is that insects exploit or pollinate 
flowers to the best abilities of the structures of their mouthparts (Patrick 
mentions the plant-insect coevolution above).  Butterflies are specialists 
of plants with tube-shaped nectaries (the use of the longer or  shorter 
nectaries being dependent on the size of their proboscis).  They also feed 
on nectar found in the base of flowers with tube shaped corollas.  I think 
of bees as being more generalist pollinators with a broader range of 
nectaring sources.  In the case of roses, the nectar is contained in a 
shallow structure readily accessible to also flies and wasps.  Flies and 
other insects with smaller mouthparts that lack the ability to suck nectar 
from tube-shaped nectaries are confined to flowers with flat corollas.

Interestingly, in "The Forgotten Pollinators" by Stephen L. Buchmann & Gary 
P. Nabhan, the authors wrote that among the pollinator classes for the 
world's flowering plants, 8% of the total of the world's flowering plants 
are pollinated by butterflies and moths, 16.6% by bees, and 88.3% by 
beetles.

Rudy/Maryland


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