[Pollinator] Fact Checking?

[Peter Bernhardt]

Dear Carlos:

This is not the most convincing footage.  Domesticated coffee is
self-compatible.  How do you know that the flower didn't pollinated itself
before the bee arrived?  The flowers in your video look sort of well...
wilted and browned.  I see no evidence that the bee hit the stigma while
foraging.  Perhaps it was scavenging for pollen but how do you know that
the stigma was still receptive to viable pollen at that time?

This is what I'm trying to clarify for all of us as we take our case to the
public because we are also taking sides.  Vigorous and efficient pollen
collection by any bee does not mean that the bee must "bonk" the receptive
stigma with its pollen-laden body while it forages because pollen
collection isn't pollination.  It also doesn't mean that the bee visited
the flower while the stigma was receptive.  Honeybees gather pollen
actively from pussy willow catkins every warm day in late winter, or early
spring, but unless they visit the female catkins (often on isolated twigs)
pollination has not occurred at all.  Likewise, if a bee visits only male
squash-pumpkin blossoms has the flower been pollinated?  Ideally, the
question of who pollinates what depends ultimately on the results of
exclusion experiments in association with pollen-pistil tests to determine
the self-incompatibility system and when stigmas are receptive to incoming
grains.  However, we could all be doing a better job if we waited, watched
and observed contact between a prospective pollinator and a stigma.  I wear
opti-visors in the field and can now say I've seen this contact.

Considering the way coffee displays its flowers and the absence of
pigmentation I've often wondered how wild shrubs get by in their native
Africa?  I'll bet that the best pollinators are various settling moths
(often at dusky or night) and this is replayed in plantations through Latin
America but few watch.  I remember eating the "coffee honey" sold by
apiculturists in El Salvador for two years.  Yes, the honeybees visited the
flowers but were they pollinating the flowers at a higher and more
successful frequency than the natural rate of dehiscent anthers contacting
viable stigmas without insect contact?  Our laboratory is completing a two
year study on the pollination of Viola pedata at two isolated sites.  We
collected 6 species of bees carrying the pollen of the host flower.  Should
I write that this species had six pollinators at my sites or should I be a
little more cautious and say it has six "prospective/potential"
pollinators?  About 80% of the bees we caught were the same species and,
yes, I saw them contact the stigma.  I can say the same thing for a second
species but the remaining four were rather small and uncommon so maybe so
and maybe not.

Peter

On Mon, Nov 9, 2015 at 12:10 PM, <carloshvergara at yahoo.com> wrote:

> Hi, Peter.
>
> I have recorded Scaptotrigona mexicana pollinating coffee in Veracruz,
> Mexico and Scaptotrigona ederi pollinating coffee in Santa Elena Ecuador.
> They are indeed small, but they move intensively about the coffee flowers
> and chew on the anthers to collect pollen.
>
> I am attaching a photograph of S. mexicana and a very short
> (unfortunately) video of S. ederi.
>
> Carlos H. Vergara
>
>
>
> El Lunes, 9 de noviembre, 2015 11:54:28, Peter Bernhardt <bernhap2 at slu.edu>
> escribió:
>
>
> Within the last week there two statements appeared regarding the the
> pollination of crops.  The comments of members working on bee-pollination
> of crops would be appreciated.
>
> 1) November 5, Saint Louis U.  A bee conservation lecture series was
> held.  One of the speakers was Gerald Hayes from Monsanto on the role of
> honeybees and our food supply.  Hayes insisted that our North American,
> cultivated, cranberries were pollinated by honeybees.  Is this correct?  I
> remember a seminar by Jim Cane emphasizing the importance of native
> megachilids for cranberry pollination.  The speaker also insisted that
> blueberries were pollinated primarily by honeybees in North America.
>
> 2) CJ Bradshaw and Paul Ehrlich released a coauthored by book from
> University of Chicago Press (my publisher) last month.  On page 58 the
> authors insist that Trigona (species not identified) pollinates 90 species
> of crop plants including coffee.  I know that most coffee marketed today is
> self-pollinating although it still yields sufficient nectar for introduced
> honeybees to make honey but what of the other 89 other crop species?  I am
> aware that Trigona pollinate avocados, macadamias and a few other fruit/nut
> trees but, generally speaking, their bodies are too small to contact both
> anthers and stigmas as they forage.
>
> Peter
>
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