Research about Native Bees:
Native bees can play a very important role in the
pollination of
crops and wild plants. Martin Holdrege, a highschool student at
Hawthorne Valley School, has been helping as explore these important
insects. The following is derived from a power-point presentation he
put together summarizing his work. Because it is derived from slides
from a talk, the format is a bit telegraphic, but it does a good job of
summarizing what we did.
Goals of
our Study
With
colony collapse disorder affecting honey bees, native bees may become
more
crucial in crop pollination and there is a growing interest in them.
Specifically, we would like to answer the following questions:
Who
pollinates whom regionally?,
What value do native bees have
relative to Honey Bees when considering crop pollination services?
How consistent are
pollinator/crop
relations across farms?
How
does one manage for native bees on
farms?
Through our work we are also hoping to familiarize farmers with native
bees and create a baseline of bee data for various farms.
What We Did
We
looked at seven organic farms in Columbia
County
during the summer of 2007.
We
observed and collected bees from 12 crops and from a
variety of on-farm wild flowers.
We
collected information in three different ways: Visual
Surveys, Netting, and Bee Bowls.
Visual Survey:
10-minute long counts of
insects observed on a particular
type of plant.
Insects observed were
categorized as:
Bumble
bees
Metallic
(green)
sweat bees
Honey
Bees
Flies<
Wasps
Other
(native) bees
PROS
of this technique
Gives
an idea of relative value of different insect groups
as pollinators (for example, Honey Bees vs. Native Bees).
Gives
additional information on Honey Bee abundance.
CONS of
this technique
One
cannot ID most bees on the wing.
Netting:
We used
butterfly nets to catch bees that were on
the flowers of
plants.
Almost
all bees cannot be ID without a microscope. For this
reason visual surveys alone will not suffice.
We
usually netted for 20 minutes or more
PROS
of this technique
Netting
lets us know
that a bee was actually visiting a flower, unlike bowls.
When
netting, Bumble Bees can be caught; these bees are rarely
caught in bee bowls.
The
collector
can be selective about what is caught.
CONS of
this technique
The
number and type of bees caught can depend
on the
collectors skill.
Relative
numbers of bees caught cannot be estimated.
Gives
snapshot of bees present.
Can
be time consuming.
A pair of eager Netters.
Bee
Bowls:
Fluorescent
blue, yellow, and white cups—attract native
bees, rarely Honey
Bees.
Filled
with soapy water that drowns bees.
Bowls
put along plants.
PROS of
this technique
Less
labor intensive than netting.
Bowls
can be out for 24 hours.
This
is a standardized
procedure, it allows comparison with other researchers.
May
help to detect management effects.
Requires
minimal
skill.
CONS of
this technique
Rarely
catch Bumble Bees.
Do
not document bees’ presence on plants.
Specimens
need hair dresser.
Bee Bowls set out along peppers.
My Collection:
Bees
collected in bowls and by netting were labeled and
pinned for later identification.
Some of the pinned bees from Martin's
collection.
Preliminary Results:
14
genera and 24 species of native bees have so far been identified
from sampling done on three farms.
All identifications
are preliminary, and many were only
identified to the generic level.
A list of the bees found to date.
Data on the distribution of pollinators
across crops from Roxbury Farm.
The number of native bees and Honey Bees
obsereved on the flowers of various crops during 10-minute observation
periods.
Note that native bees tended to be more
common, except on cucumbers.
An Example of Management
Considerations:
Lasioglossum
seems to be the most common genus of native bees thus far.
For example, at Roxbury Farm, Lasioglossum spp.
were found on or along 4 of the
6 crops surveyed.
Because Lasioglossum spp.
probably have significant
pollination value it may be wise to manage for them. Managing for them
might
include the following:
- Increasing
extent and duration
of flowers; Lasioglossum
bees fly from Spring to Fall and need adequate
pollen & nectar during that entire period.
- Increasing ground nesting
sites is probably
important; good sites should be near crops, on well-drained soils,
sandy, and with little vegetation.
Useful Resources:
The Bee
Genera of Eastern Canada, by Laurence Packer,
Julio
A. Genaro and Cory S. Sheffield, has a nice summary of native bee
identification and natural history.
Status
of Pollinators in North America
can be read on-line for free. This book was published
in 2007 and therefore the
information is up to date.
An ATTRA article
discussing the use of native bees as pollinators.
A NYS
website that has info about bees, especially
concerning bees found in NY.
The Discover
Life website has excellent keys for bee ID in
the eastern US. These are the keys we use for most of our ID work.
There are
also plenty of photographs of bees.
The Pollinator
Partnership's website has a lot of info on native and Honey
Bees.
Farming
for Bees,
by the Xerces Society, is a wonderful
article about native bee conservation, management and biology on farms.
(This is a pdf document.)
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