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Rader, R., B. G. Howlett, et al. (2012). "Spatial and temporal
variation in pollinator effectiveness: do unmanaged insects provide
consistent pollination services to mass flowering crops?" <u>Journal
of Applied Ecology</u> <b>49</b>(1): 126-134.<br><br>
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<dd>1.Recent declines in honeybee populations have focused attention on
the potential for unmanaged insects to replace them as pollinators of
food crops. The capacity of unmanaged pollinators to replace services
currently provided by honeybees depends on the spatial and temporal
variability of these services, but few quantitative assessments currently
exist. <br>
<dd>2.We investigated spatial variation in pollinator importance by
comparing pollinator efficiency and effectiveness in stigmatic pollen
loads, stigmatic contact and visitation rate between honeybees and the
seven most abundant unmanaged taxa in 2007. We assessed temporal
variability in pollinator visitation using floral visits recorded three
times a day over four consecutive years (2005 in 43 Choirapa ssp.
chinensis mass flowering fields in the Canterbury region of New Zealand.
Further, we compared the aggregate effect of the unmanaged pollinator
assemblage to the managed honeybee. <br>
<dd>3.Pak Choi was visited by many insect species that vary in abundance
and effectiveness as pollen transfer agents. There was spatial variation
in the four measures of pollinator importance. Pollen deposited on
stigmas and flower visits per minute were not significantly different
comparing the unmanaged assemblage to honeybees, although stigmatic
contact and visitor abundance per number of open flowers were greater in
honeybees. <br>
<dd>4.Unmanaged taxa were frequent visitors to the crop in all 4 The
pooled services provided by the unmanaged assemblage did not differ
within a day and were equal to or greater than those provided by
honeybees in 2 of the 4 Pollinator importance changed little irrespective
of the spatial and temporal variations among taxa. <br>
<dd>5.Synthesis and applications. The results of this study suggest that
some unmanaged insect taxa are capable of providing consistent
pollination services over a 4-year period in a commercial mass flowering
crop. As these taxa already contribute substantially to the pollination
of food crops, they offer a safety net in the case of sudden collapse of
managed honeybee hives. To optimize pollination services, we recommend
pollinator-specific farm management practices that consider the needs of
both managed and unmanaged pollinator taxa.<br><br>
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