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Pollen harvesting and reproductive rates in specialized solitary bees

Franzén, Markus LU and Larsson, Magnus (2007) In Annales Zoologici Fennici 44(6). p.405-414
Abstract
Andrena humilis is an endangered oligolectic solitary bee and has declined in recent decades throughout western Europe. The aim of this study was to explore the pollen harvesting pattern and to determine the reproductive rate in specialized andrenid bees. We measured the amount of pollen required to produce one brood-cell, the pollen harvesting rate and compared our results with data for other specialized andrenid bee species. Pollen-foraging trips were registered and the activity events (entering, leaving or digging) recorded at the nests. The mean number of pollen-foraging trips per day was 5.3 and an average bee nest was active (and open) 88 min day(-1). The bees were highly efficient in harvesting pollen and spent on average 10.7 min... (More)
Andrena humilis is an endangered oligolectic solitary bee and has declined in recent decades throughout western Europe. The aim of this study was to explore the pollen harvesting pattern and to determine the reproductive rate in specialized andrenid bees. We measured the amount of pollen required to produce one brood-cell, the pollen harvesting rate and compared our results with data for other specialized andrenid bee species. Pollen-foraging trips were registered and the activity events (entering, leaving or digging) recorded at the nests. The mean number of pollen-foraging trips per day was 5.3 and an average bee nest was active (and open) 88 min day(-1). The bees were highly efficient in harvesting pollen and spent on average 10.7 min to complete one pollen-foraging trip. Most pollen-foraging trips (77%) were completed in less than 15 min. The duration of pollen-foraging trips increased over the day, presumably because pollen became more costly to harvest. Based on pollen counts (pollen loads on bees and pollen provisions) an average bee required 3.85 foraging trips to complete one brood cell and one bee managed to accomplish 1.37 brood cells in one day with suitable weather. In the literature we found data on an additional 19 specialized andrenid bee species. Andrena humilis seems to be extremely efficient compared with most other species, with an average trip for pollen lasting almost one hour (average for andrenid bees = 46 min). An extremely low reproductive rate seems to be a common trait among specialized bees in the family Andrenidae with an average 0.9 offspring produced per day and less than ten offspring produced during the whole lifetime. The high degree of specialisation and the low reproductive rate among andrenid bees can explain the severe decline in many species today. (Less)
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organization
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Contribution to journal
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published
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in
Annales Zoologici Fennici
volume
44
issue
6
pages
405 - 414
publisher
Finnish Zoological and Botanical Publishing Board
external identifiers
  • wos:000252271500002
  • scopus:38349006692
ISSN
0003-455X
language
English
LU publication?
yes
id
5dfa2bd8-89ce-4a86-b41f-e39996c29760 (old id 1408328)
alternative location
http://www.sekj.org/PDF/anz44-free/anz44-405.pdf
date added to LUP
2009-05-29 12:48:59
date last changed
2017-01-01 06:48:29
@article{5dfa2bd8-89ce-4a86-b41f-e39996c29760,
  abstract     = {Andrena humilis is an endangered oligolectic solitary bee and has declined in recent decades throughout western Europe. The aim of this study was to explore the pollen harvesting pattern and to determine the reproductive rate in specialized andrenid bees. We measured the amount of pollen required to produce one brood-cell, the pollen harvesting rate and compared our results with data for other specialized andrenid bee species. Pollen-foraging trips were registered and the activity events (entering, leaving or digging) recorded at the nests. The mean number of pollen-foraging trips per day was 5.3 and an average bee nest was active (and open) 88 min day(-1). The bees were highly efficient in harvesting pollen and spent on average 10.7 min to complete one pollen-foraging trip. Most pollen-foraging trips (77%) were completed in less than 15 min. The duration of pollen-foraging trips increased over the day, presumably because pollen became more costly to harvest. Based on pollen counts (pollen loads on bees and pollen provisions) an average bee required 3.85 foraging trips to complete one brood cell and one bee managed to accomplish 1.37 brood cells in one day with suitable weather. In the literature we found data on an additional 19 specialized andrenid bee species. Andrena humilis seems to be extremely efficient compared with most other species, with an average trip for pollen lasting almost one hour (average for andrenid bees = 46 min). An extremely low reproductive rate seems to be a common trait among specialized bees in the family Andrenidae with an average 0.9 offspring produced per day and less than ten offspring produced during the whole lifetime. The high degree of specialisation and the low reproductive rate among andrenid bees can explain the severe decline in many species today.},
  author       = {Franzén, Markus and Larsson, Magnus},
  issn         = {0003-455X},
  language     = {eng},
  number       = {6},
  pages        = {405--414},
  publisher    = {Finnish Zoological and Botanical Publishing Board},
  series       = {Annales Zoologici Fennici},
  title        = {Pollen harvesting and reproductive rates in specialized solitary bees},
  volume       = {44},
  year         = {2007},
}