Tag Archives: bumble bees

357-360 R. Muljar, E. Viik, R. Marja, E. Svilponis, K. Jõgar, R. Karise, M. Mänd
The effect of field size on the number of bumble bees
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The effect of field size on the number of bumble bees

R. Muljar¹, E. Viik¹², R. Marja³, E. Svilponis¹, K. Jõgar¹, R. Karise¹, M. Mänd¹

¹Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Kreutzwaldi 1a, 51014 Tartu, Estonia; e-mail: riin.muljar@emu.ee
²Agricultural Research Centre, Riia 24D, 51010 Tartu, Estonia.
³Institute of Ecology and Earth Sciences, University of Tartu, Vanemuise 46, 51014 Tartu, Estonia.

Abstract:

Bumble  bees  are  important  pollinators  in  agricultural  and  natural  ecosystems.  In recent decades their numbers  have been declining due to the intensification of agriculture and establishment of large homogenous fields. Our goal was to study the effect of the field size on the  abundance  of  bumble  bees  in  Estonia.  The  data  was  collected  from  66  farms  located  in different  regions  of  the  country.  Bumble  bees  were  counted  along  the  field  transect  of  each farm.  The  relationship  between  field  size  and  number  of  bumble  bees  present  was  calculated. We found a negative correlation between the  field  size and the abundance of bumble bees: as the field area increased the number of bees decreased.

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211-216 R. Karise, M. Mänd, M. Ivask, E. Koskor and A. Bender
The effect of pollen amount and its caloric value in hybrid lucerne (Medicago x varia) on its attractiveness to bumble bees (Bombus terrestris)
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The effect of pollen amount and its caloric value in hybrid lucerne (Medicago x varia) on its attractiveness to bumble bees (Bombus terrestris)

R. Karise¹, M. Mänd¹, M. Ivask², E. Koskor¹ and A. Bender³

¹Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences,Kreutzwaldi St. 64, Tartu 51014, Estonia; e-mail: reet.karise@emu.ee
²Institute of Sustainable technology at Tallinn University of Technology,Akadeemia 4, Tartu 51003
³Jõgeva Plant Breeding Institute, 48309 Jõgeva, Estonia

Abstract:

Bumble bees forage for pollen and nectar on various plant species, but individuals often restrict their choice to a few flower types. The aim of this work was to study whether there is variation in certain pollen characteristics between differently coloured flowers of hybrid lucerne and whether this could be the reason why bumble bees prefer one flower type to another. The pollen amount, pollen grain size and the caloric values from different flower types were analysed to study the reasons for flower colour preference. On two cultivars of hybrid lucerne (Medicago x varia Mart.) the yellow flowers were preferred, but the reasons for the preference differed.

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