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Ings, T. C., N. L. Ward, and L. Chittka. 2006. Can commercially imported
bumble bees out-compete their native conspecifics? Journal of Applied
Ecology <b>43</b>:940-948.<br><br>
Summary<br>
<b>1.</b> 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><br>
<b>2.</b> 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><br>
<b>3.</b> 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><br>
<b>4.</b> 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><br>
<b>5.</b> <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>
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