1718RE: [beemonitoring] Megachile apicalis - The Hidden Bee - A Cautionary Tale
- Aug 3, 2011
We have records of Megachile apicalis from CA, and from golf courses in OR & southern WA. We have no field caught records from UT or anywhere else in the Great Basin & Colorado Plateau. The suggestion of UT might have come from specimens in our collection that are labeled “Logan Greenhouse” and were flown in caged experiments. These are not being served on GBIF.
USDA ARS Bee Biology & Systematics Laboratory
Utah State University
Logan, UT 84322-5310
Thanks for this interesting posting.
Megachile apicalis is also on my mind this weekend, as I observed a
probable female yesterday with a full pollen load and obtained this
I did not collect a voucher as it was on federal parkland at Floyd Bennett
Field. If anyone has an opinion about my probable M. apicalis ID or can
confirm ID of the host plant please email me directly.
Regarding the map pasted in Sam's email, please note that the actual known
distribution of M. apicalis is considerably narrower than depicted,
because the map in question includes state record centroids from my
AMNH_BEES literature database in addition to georeferenced specimen
records. To display only georeferenced specimen records, simply click on
"Customize this Map" and then set "Map points using" to "coordinates" (not
"both" coordinates and gazetteer which is the default setting). In this
case it was not ideal to make the default map (optimized for speed) as
this, taken at face value, gives a misleading impression of the bee's
actual occurrence. I hope all advanced users of DL can consistently convey
the need to use customized maps for any sophisticated purpose (such as
precisely plotting confirmed localities for a bee species) and to realize
that data are owned in all cases by particular data providers with
differing standards of identification and georeferencing quality. One
cannot expect an optimal result when accepting all records in the global
repository GBIF (very keen to add hundreds of millions of records in the
absence of any adequate methods to error-check or update these), mixing
literature reports with precise specimen records, and generating maps with
the most convenient option as opposed to taking advantage of advanced
mapping options. In all cases it is necessary to credit individual data
providers rather than simply citing "Discover Life" as a catch-all source
as was done in recent species distribution modeling papers on Anthidium
manicatum and on South American Peponapis.
When the map of M. apicalis is customized to show display only specimen
records, these cluster rather tightly along the NYC-to-DC corridor
(exluding the outlying Elmira, NY record), in cismontane California (esp.
in and around the Central Valley), and a limited area of NE OR and SE WA.
Sam, please double check your Elmira, NY record. This is of considerable
interest, as in my experience the only Eutricharaea found in the greater
Fingerlakes Region of NY is rotundata. There are no apicalis records from
Ithaca and vicinity despite very extensive collecting. Nearly all NY
records of apicalis seem to be from NYC.
"widespread in the West"
This has not been demonstrated, at least based on specimen records
displayed on DL. It is certainly widespread and very abundant in CA and
also well known from NE OR and SW WA, but it's occurrence elsewhere in the
west is not well documented.
Terry, please verify if there is a valid Utah record (I have a state
record but no specimen records are mapping on DL yet)?
"Surely there are recent Canadian records.... "
This seems to be pure speculation. I am aware of a "Canada" record but
don't have any details of this and cannot confirm it. It would useful to
confirm even one Canadian record of any age attributable to a province.
"the real status of, in particular, the loosestrife specialists if nobody
is looking on loosestrife plants...."
By this do you mean yellow or purple loosestrife. There is an important
difference! Both have specialist bees at least where native.
If you mean yellow loosestrife, bee specialists have certainly looked for
Macropis on Lysimachia in recent decades but are finding them only
locally. By contrast, in the late 19th and early 20th centuries this genus
was found by many collectors (including general entomologists) from many
collectors in the vicinity of cities such as NYC, Boston, and DC. Most
recent records are by specialist bee collectors from relatively few sites.
Macropis have genuinely become hard to find but still exist at the most
favorable remaining localities most of which are distant from cities.
The case of Megachile apicalis, with its surprisingly limited confirmed
distribution when maps are made and interpreted precisely, illustrates why
it is important to map records with caution (being sure to screen out
imprecise gazetteer centroids and suspicious georeferenced points from
certain data providers) when considering the details of bee distributions.
It also shows why it is is better to precisely delimit and even enumerate
species ranges in preference to making misleading generalizations such as
"widespread in the West" (as in Sam's draft text) or "e. U.S." (Cane
2001). Our exotic and native bees are both more and less widespread in
time and space than we might assume, and we must take care to use
available resources optimally if we want to understand past and present
distributional patterns. It's great to be concise when citing species
ranges, but not at the expense of accuracy, especially in the case of
species with dynamic and poorly documented ranges such as M. apicalis.
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