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Journal of Applied Ecology<br>
Online Early<br>
doi:10.1111/j.1365-2664.2006.01199.x<br>
Volume 0 Issue 0<br>
<br>
<br>
Can commercially imported bumble bees out-compete their native
conspecifics?<br>
T. C. INGS*, N. L. WARD†‡ and L. CHITTKA*<br>
<a name="h1"></a> Summary<br>
<b>1.</b> <br><br>
Although invasive species are major topics of research, little
consideration has been given to the implications of introducing
non-native subspecies or beneficial organisms such as pollinators.
However, the extensive trade in bumble bees as pollinators of glasshouse
crops involves both. Within regions in Europe, the importation of
non-native commercially reared subspecies of <i>Bombus terrestris</i>
could endanger native bumble bees through competitive displacement and/or
hybridization.<br>
<b>2.</b> <br><br>
This study made a direct ecological comparison between commercially
imported and native <i>B. terrestris</i> colonies growing in the wild in
the UK. In particular, using a paired design, we compared the
nectar-foraging performance and reproductive outputs of commercial and
native colonies growing under identical field conditions.<br>
<b>3.</b> <br><br>
Commercial colonies performed well in the field, with substantially
higher nectar-foraging rates than native colonies in four out of five
locations. Nectar-foraging performance was positively correlated with
forager size, with commercial bees being consistently larger than native
bees.<br>
<b>4.</b> <br><br>
All seven commercial colonies studied produced gynes (new queens), with
two colonies each producing in excess of 50. In contrast, only two out of
seven native colonies produced gynes, and those only produced small
numbers (five in total). Males were produced by all colonies but there
were no significant differences in numbers between commercial and native
subspecies.<br>
<b>5.</b> <br><br>
<i>Synthesis and applications.</i> The high reproductive success of
commercial colonies indicates that there is an appreciable risk that they
will become established and spread within the UK. Furthermore, their
superior foraging ability and large colony size could lead them to
out-compete native bumble bees. Clearly the invasive potential of
non-native subspecies and/or beneficial organisms should not be
overlooked. With respect to the current importation of commercial bumble
bees, we strongly recommend a precautionary approach: native species and
subspecies should be locally reared and the use/disposal of bees should
be strictly regulated.<br><br>
<i>Journal of Applied Ecology</i> (2006)<br>
doi: 10.1111/j.1365-2664.2006.01199.x<br>
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