<html>
<body>
At 04:34 PM 3/28/2013, you wrote:<br>
<blockquote type=cite class=cite cite="">Dear Readers,<br>
<br>
Genetically modified (GM) alfalfa is up for commercialization in Ontario.
Industry argues that since alfalfa is pollinated by leafcutter bees which
don't travel far, and not by honeybees, pollinator-mediated GM
contamination is not a problem. Critics argue that cross contamination is
inevitable.<br><br>
I am reaching out to you, in the hopes that you might kindly provide
answers to the following questions. The answers primarily revolve around
the need for solid academic citations -- whether they are published
studies or simply your personal word. If the information below is
incorrect in any way, please let me know. <br>
<br>
1) My impression is that leafcutter bees do not usually travel far. Their
maximum range seems to be about 650-750m. However, I have heard that they
may travel further over time to search for better bloom, and may relocate
further via strong winds and storms. Is this true? If so, do we have an
estimate for the far end of their range? (Source?) </blockquote><br>
Beil, M., H. Horn, et al. (2008). "Analysis of pollen loads in a
wild bee community (Hymenoptera: Apidae) a method for elucidating habitat
use and foraging distances." <u>Apidologie</u> <b>39</b>(4):
456-467.<br>
<dl>
<dd><x-tab> </x-tab>
Resource utilisation and foraging ranges of Apidae (excluding Apis and
Bombus) were studied in sandy grasslands of the temperate zone by pollen
analysis combined with direct observation of bees. Plant-taxa composition
of 558 pollen loads collected from 56 bee species was determined. We
recorded flower-visits using plot-based observations and resource
utilisation using pollen analysis. For the most important entomophilous
plant species flower-visitation and pollen-analytical data correspond
(e.g. Berteroa incana, Centaurea stoebe, Potentilla argentea). Whenever
pollen of plant species that are limited in their occurrence could be
detected, we were able to use pollen analysis to determine foraging
distances, but not maximum foraging distances. Using tree pollen, minimum
flight ranges up to 1250 m were documented even for bees with 7 mm body
size. Thus pollen analysis not only provides valuable information about
foraging on different spatial scales, but also enables foraging ranges to
be calculated without experimental manipulation. <br><br>
</dl>Gathmann, A. and T. Tscharntke (2002). "Foraging ranges of
solitary bees." <u>Journal of Animal Ecology</u> <b>71</b>:
757-764.<br>
<dl>
<dd><x-tab> </x-tab>1.
Habitat requirements of solitary bees include nesting sites, food
resources and nesting material. We used translocation experiments to
establish foraging distances and measured foraging trip duration to
analyse how solitary bees cope with the distance between nesting sites
and suitable food plants in different habitat types. <br>
<dd>2. Maximum foraging distance between nesting site and food patch was
150-600 m for the 16 bee species examined. Foraging distance was
correlated positively with body length. Mean foraging trip duration,
measured for seven bee species, ranged from 6 to 28 min and was also
correlated with body length. In a study of the polylectic species Osmia
rufa, we found a significant decrease in foraging trip duration with
increasing number of plant species. Logistic regressions showed that the
oligolectic Megachile lapponica nested in trap nests with a probability
of 50% if the distance between trap nest and food patch was less than 250
m. The oligolectic Chelostoma rapunculi utilized trap nests when the
distance to the nearest food patch was less than 300 m. <br>
<dd>3. These experiments showed that solitary bees have a rather small
foraging range so local habitat structure appears to be of more
importance than large-scale landscape structure. All requirements for
sustaining viable populations must be within this range. Therefore, it is
necessary to maintain and restore a dense network of habitat patches in
landscapes to ensure long-term sustainability of wild bee diversity and
their ecological function as pollinators.<br><br>
</dl>Gu C., J. Bosch, et al. (2009). "Relationship between body size
and homing ability in the genus <i>Osmia </i>(Hymenoptera;
Megachilidae)." <u>Ecological Entomology</u> <b>34</b>(1):
158-161.<br>
<dl>
<dd><x-tab> </x-tab>1.The
maximum homing ability of female bees, that is, their capacity to return
to the nest after being displaced a certain distance, is considered to be
an estimate of their maximum foraging distance. <br>
<dd>2.The present study provides data on homing ability and body weight
for Osmia lignaria and combines them with data for five other
congenerics, O. rufa, O. cornuta, O. pedicornis, O. cornifrons, and O.
emarginata for analysis. These species are important pollinators of
spring-flowering plants, and some have been developed as commercial crop
pollinators. <br>
<dd>3.It is shown that homing ability is positively and linearly related
to body weight (r281; P01). <br>
<dd>4.These results should be of use in selecting Osmia species as
potential crop pollinators and establishing adequate buffer distances
around genetically modified crops.<br><br>
</dl>Zurbuchen, A., L. Landert, et al. (2010). "Maximum foraging
ranges in solitary bees: only few individuals have the capability to
cover long foraging distances." <u>Biological Conservation</u>
<b>143</b>(3): 669-676.<br>
<dl>
<dd><x-tab> </x-tab>To
preserve populations of endangered bee species, sound knowledge of their
maximum foraging distance between nest and host plants is crucial.
Previous investigations predicted maximum foraging distances of
100-200for small bee species and up to 1100for very large species based
on mainly indirect methods. The present study applied a new and direct
approach to experimentally investigate maximum foraging distances in
solitary bees. One endangered and two common species of different body
sizes, all of which restrict pollen foraging to a single plant genus,
were established in a landscape lacking their specific host plants.
Females were forced to collect pollen on potted host plants that were
successively placed in increasing distance from fixed nesting stands. The
maximum foraging distance recorded for the small Hylaeus punctulatissimus
was 1100 for the medium sized Chelostoma rapunculi 1275and for the large
Hoplitis adunca 1400 indicating that maximum foraging distances at
species level have been underestimated. However, the capability to use
resources on such a large spatial scale applied only to a small
percentage of individuals as 50% of the females of H. punctulatissimus
and H. adunca did not forage at distances longer than 100-225and 300
respectively. This finding suggests that a close neighbourhood of nesting
and foraging habitat within few hundred meters is crucial to maintain
populations of these species, and that threshold distances at which half
of the population discontinues foraging are a more meaningful parameter
for conservation practice than the species specific maximum foraging
distances.<br><br>
<br>
<blockquote type=cite class=cite cite="">
</dl> <br>
3) Honeybees don't tend to pollinate alfalfa because they don't
appreciate the trip mechanism of the alfalfa flower, which hits them on
the head. However, this is apparently a learned behaviour, and juvenile
honeybees may pollinate alfalfa flowers. Are there any citations for this
possibility/reality? We are arguing that even though honeybees, which
have longer foraging distances, do not commonly pollinate alfalfa, that
doesn't mean that honeybee-mediated cross-contamination doesn't take
place.<br>
<br>
4) Finally, I realize that a number of other native pollinators,
including bees and wasps, also visit and pollinate alfalfa. Other than
alkali bees, which other types of bees and wasps can be named?<br>
</blockquote>Bohart, G. E. (1957). "Pollination of alfalfa and red
clover." <u>Annual Review of Entomology</u> <b>2</b>: 355-380.<br>
<dl>
<dd><x-tab> </x-tab><br>
</dl>Brookes, B., E. Small, et al. (1994). "Attractiveness of
alfalfa (<i>Medicago sativa</i> L) to wild pollinators in relation to
wildflowers." <u>Canadian Journal of Plant Science</u> <b>74</b>(4):
779-783.<br>
<dl>
<dd><x-tab> </x-tab>This
study attempted to assess the effects of proximity to wildflowers on the
relative number of pollinators foraging on alfalfa flowers, as this
information may bear on alfalfa seed production, an important industry in
Canada. Five hundred and forty-five collections were made of wild
pollinating bees attracted to 20 alfalfa plantations in Canada. Of the 13
genera of bees collected, almost half belonged to Megachile, followed by
Bombus with 20% of the collections. Analysis indicated that increased
visitation to alfalfa was significantly related to distance of the
alfalfa from wildflowers, but not to the size of the alfalfa plantation.
Alfalfa growing less than 10m from wildflowers seemed to benefit by
spill-over ("facilitation") of pollinators from the
wildflowers. Alfalfa isolated from wildflowers by other alfalfa plants
for a distance of at least 200m attracted very few pollinators, the
wildflowers apparently providing more attractive sources of pollen and
nectar. A single plantation highly isolated (by about 600m) from
wildflowers proved to be very attractive to pollinators, apparently
because wild nesting bees in the vicinity had little alternative but the
alfalfa. These observations may be useful in exploring crop layouts to
maximize attraction of wild pollinators for seed production. Key
words:Medicago sativa, alfalfa, pollinators, competition, facilitation,
seed production<br><br>
</dl>Brunet, J. and C. M. Stewart (2010). "Impact of bee species and
plant density on alfalfa pollination and potential for gene flow."
<u>Psyche</u> <b>2010</b>: Article ID 201858.<br>
<dl>
<dd><x-tab> </x-tab>In
outcrossing crops like alfalfa, various bee species can contribute to
pollination and gene flow in seed production fields. With the increasing
use of transgenic crops, it becomes important to determine the role of
these distinct pollinators on alfalfa pollination and gene flow. The
current study examines the relative contribution of honeybees, three
bumble bee species, and three solitary bee species to pollination and
gene flow in alfalfa. Two wild solitary bee species and one wild bumble
bee species were best at tripping flowers, while the two managed
pollinators commonly used in alfalfa seed production, honeybees and leaf
cutting bees, had the lowest tripping rate. Honeybees had the greatest
potential for gene flow and risk of transgene escape relative to the
other pollinators. For honeybees, gene flow and risk of transgene escape
were not affected by plant density although for the three bumble bee
species gene flow and risk of transgene escape were the greatest in
high-density fields.<br><br>
</dl>Holm, S. N. (1966). "The utilization and management of bumble
bees for red clover and alfalfa seed production." <u>Annual Review
of Entomology</u> <b>11</b>(1): 155-182.<br>
<dl>
<dd><x-tab> </x-tab><br>
</dl>Jones, J. S. and E. T. Bingham (1995). "Inbreeding depression
in Alfalfa and cross-pollinated crops." <u>Plant Breeding
Reviews</u> <b>13</b>: 209-233.<br>
<dl>
<dd><x-tab> </x-tab><br>
</dl>Katepamupondwa, F. M., D. K. Barnes, et al. (1996). "Influence
of parent and temperature during pollination on alfalfa seed weight and
number of seeds per pod." <u>Canadian Journal of Plant Science</u>
<b>76</b>(2): 259-262.<br>
<dl>
<dd><x-tab> </x-tab><br>
</dl>Pesenko, Y. A. and V. D. Radchenko (1993). "The use of bees
(Hymenoptera, Apoidea) for alfalfa pollination: the main directions and
modes, with methods of evaluation of populations of wild bees and
pollinator efficiency." <u>Entomological Review</u> <b>72</b>(2):
101-119.<br>
<dl>
<dd><x-tab> </x-tab><br>
</dl>Pitts-Singer, T. L. and J. H. Cane (2011). "The alfalfa
leafcutting bee, <i>Megachile rotundata</i>: The world's most intensively
managed solitary bee." <u>Annual Review of Entomology</u>
<b>56</b>(1): 221-237.<br>
<dl>
<dd><x-tab> </x-tab>The
alfalfa leafcutting bee (ALCB), Megachile rotundata F. (Megachildae), was
accidentally introduced into the United States by the 1940s. Nest
management of this Eurasian nonsocial pollinator transformed the alfalfa
seed industry in North America, tripling seed production. The most common
ALCB management practice is the loose cell system, in which cocooned bees
are removed from nesting cavities for cleaning and storage. Traits of
ALCBs that favored their commercialization include gregarious nesting;
use of leaves for lining nests; ready acceptance of affordable,
mass-produced nesting materials; alfalfa pollination efficacy; and
emergence synchrony with alfalfa bloom. The ALCB became a commercial
success because much of its natural history was understood, targeted
research was pursued, and producer ingenuity was encouraged. The ALCB
presents a model system for commercializing other solitary bees and for
advancing new testable hypotheses in diverse biological
disciplines.<br><br>
</dl>Richards, K. W. (2003). "Potential use of the alfalfa
leafcutter bee <i>Megachile rotundata</i> to pollinate sweet
clover." <u>Journal of Apicultural Research</u> <b>42</b>(1-2):
21-24.<br>
<dl>
<dd><x-tab> </x-tab>The
effectiveness of the alfalfa leafcutter bee, Megachile rotundata, as a
potential pollinator of biennial yellow sweet clover, Melilotus
officinalis, and biennial white sweet clover, Melilotus alba, and its
potential to reproduce on the crop were evaluated over a 2-year period.
Populations of the most important pollinator of the crop, the honey bee,
Apis mellifera, continue to decrease in North America, thus there is a
need to evaluate alternative pollinators so that seed growers can
optimise their choice of pollinator. Treatments consisted of plants caged
to exclude all pollinators, plants caged with leafcutter bees, and plants
exposed to all resident pollinators including alfalfa leafcutter bees.
The sweet clovers were essentially self-sterile and produced very little
seed when bees were excluded. Percentage seed set and yield were higher
for plants exposed to resident pollinators compared to plants caged with
leafcutter bees, except in one year for yellow sweet clover. The
propagation rate and quality of alfalfa leafcutter bees produced on sweet
clover was excellent. The alfalfa leafcutter bee can be recommended as an
effective pollinator of sweet clover, thus increasing the options
available to seed growers and beekeepers regarding choice of pollinator
<br><br>
</dl>Strickler, K. (1997). "Flower production and pollination in
<i>Medicago sativa</i> L. grown for seed: model and monitoring
studies." <u>Acta Horticulturae</u> <b>437</b>: 109-113.<br>
<dl>
<dd><x-tab> </x-tab><br>
</dl>Strickler, K. (1999). "Impact of flower standing crop and
pollinator movement on alfalfa seed yield." <u>Environmental
Entomology</u> <b>28</b>(6): 1067-1076.<br>
<dl>
<dd><x-tab> </x-tab> For
agricultural crops that depend on pollination, the impact of flower
abundance and pollinator movement on seed or fruit yield is of economic
importance, and may have implications for crop and pollinator management.
Using alfalfa, Medicago sativa L. (Leguminosae), I tested the hypothesis
that seed set is lower when standing crop of open flowers is high than
when standing crop is low. This could occur if pollinators move more
among flowers on the same plant, causing self-pollination, when flowers
are abundant. In a greenhouse experiment I compared seed set for 3
simulated pollinator movement patterns between flowers on the same versus
different plants, under the 2 standing crop regimes generated by varying
the number of flowers hand-pollinated each day. Treatments maximized,
minimized, and were intermediate in movement between flowers on different
plants. Significantly more seeds were produced per pod when flower
standing crop was low than when standing crop was high. I hypothesized
that movement pattern would have a greater effect when standing crop was
high rather than low. Despite a trend in the expected direction, this
interaction was not significant. Field observations of within versus
between plant movement of the pollinator, Megachile rotundata (F.)
(Megachilidae), indicated that the bees visit more flowers per raceme
when standing crop is high than when standing crop is low. In a series of
hand pollinations among flowers on the same plant, seeds per pollination
decreased between the 1st flowers pollinated and later flowers pollinated
in succession. Alfalfa may yield less seed when flowers are abundant,
suggesting that early introduction of bees into alfalfa seed fields is
desirable to maintain a low flower standing crop. <br><br>
</dl>Strickler, K. and J. W. Vinson (2000). "Simulation of the
effect of pollinator movement on alfalfa seed set." <u>Environmental
Entomology</u> <b>29</b>(5): 907-918.<br>
<dl>
<dd><x-tab> </x-tab>Using
alfalfa grown for seed, we tested the hypothesis that seed set for a
fixed number of pollinations is lower when the standing crop of open
flowers is high than when it is low. This could occur if pollinators are
more likely to move between flowers on the same plant, causing
self-pollination, when flowers are abundant. The hypothesis has practical
implications for agricultural production because self-pollinations
produce fewer seeds per pod than do cross-pollinations in alfalfa. We
simulated seed set in a model that included published movement patterns
of the alfalfa leafcutting bee, Megachile rotundata (F.) (Hymenoptera:
Megachilidae), and estimates of seed set when a series of flowers on the
same plant are hand pollinated. Seed set from a fixed number of
pollinations averaged only higher when standing crop was low than
when standing crop was high. This small increase in seed set would be
difficult to detect experimentally because of high variability between
plants. M. rotundata appears to move with a 56% probability of leaving a
given raceme and a given plant; this foraging behavior results in few
flowers visited per plant. A pollinator with a higher probability of
leaving racemes and plants could set slightly more seed than M.
rotundata, whereas a pollinator with a lower probability of leaving
racemes and plants would be more affected by flower standing crop than is
M. rotundata. The distribution of flowers visited per raceme by bees in
alfalfa can be predicted by superimposing the movement probability on the
distribution of open flowers per raceme. This conceptualization of bee
movement on flowers differs from (but is not mutually exclusive of)
resource-driven optimal foraging models, and is useful for predicting
geitonogamy.<br><br>
</dl>Waller, G. D., G. M. Loper, et al. (1974). "Olfactory
discrimination by honeybees of terpenes identified from volatiles of
alfalfa flowers." <u>Journal of Apicultural Research</u>
<b>13</b>(3): 191-197.<br>
<dl>
<dd><x-tab> </x-tab>Bees
were conditioned to respond to the scent of a particular alfalfa clone,
and then tested with individual terpenes. The reverse was also done,
training bees to particular terpenes and then testing them against
different alfalfa clones. Reproductive isolation can occur through
assortative pollination of bees responding to differences in flower
scents.<br><br>
</dl>Watmough, R. H. (1999). "The potential of <i>Megachile
gratiosa</i> Cameron, <i>Xylocopa caffra</i> (Linnaeus) (Hymenoptera :
Megachilidae and Anthophoridae) and other solitary bees as pollinators of
alfalfa,<i> Medicago sativa</i> L. (Fabaceae), in the Oudtshoorn
District, South Africa." <u>African Entomology</u> <b>7</b>(2):
312-315.<br>
<dl>
<dd><x-tab> </x-tab><br>
<br>
<br><br>
<br>
<blockquote type=cite class=cite cite="">
</dl>Much obliged,<br><br>
Best regards,<br>
KiM<b><br>
--<br>
</b><br>
<b>K i m b e r l e y M. F e l l o w s<br>
</b>Pollination Outreach Coordinator<b><br>
</b><a href="http://www.seeds.ca/en.php">Seeds of Diversity</a> ~
<a href="http://www.seeds.ca/proj/poll/">Pollination Canada</a><br>
<a href="http://www.seeds.ca/fr.php">Semences du Patrimoine</a> ~
<a href="http://www.pollinisationcanada.ca/">Pollinisation Canada<br>
</a>303-40 King Street South<br>
Waterloo ON N2J 1N8 Canada<br><br>
Heard about
<a href="http://www.fooddowntheroad.ca/content/introducing-bee-friendly-farming">
Bee Friendly Farming or Gardening</a>?<br><br>
"<a href="http://www.youtube.com/watch?v=S3pIuy69UE8">Spot Your
Flower</a>" *<br>
<font size=1>* Yes, you're right ... the film uses the word 'proboscis'
incorrectly, for a moth's proboscis refers to their feeding tube, and
would be more accurately described as a tongue. In contrast, proboscis
usually refers to a nose in the vertebrate world (animals with a
backbone). A majority of pollinators inadvertently spread flower pollen
simply as they feed on pollen and nectar for their own nutritional needs.
Do not be confused -- in this film clip featuring this particular orchid
pollination, it is still plant pollen that is involved in pollination --
you can learn more about this wondrous, unusual strategy in Michael
Pollan's musings
<a href="http://ngm.nationalgeographic.com/print/2009/09/orchids/pollan-text">
Love and Lies</a>.<br>
</font>_______________________________________________<br>
Pollinator mailing list<br>
Pollinator@lists.sonic.net<br>
<a href="http://lists.sonic.net/mailman/listinfo/pollinator" eudora="autourl">
http://lists.sonic.net/mailman/listinfo/pollinator</a></blockquote></body>
</html>