Caught in a Trap: Bumblebees versus Robotic Crab Spiders

From Bee Craft: June 2009

Tom Ings, PhD and Professor Lars Chittka

Bumblebees become cautious when caught once too often by a predator

Untitled-1(2)-1

A crab spider (Misumena valid) catches a foraging bumblebee (Bombus terrestris)

One of the bumblebee’s main predators is the crab spicier. Crab spiders hunt pollinating insects like bees and butterflies by lying in wait on flowers and they are particularly difficult for their prey to spot because they can change their colour to blend in with their surroundings.

CHANGED FORAGING PATTERNS

Dr Tom Ings and Professor Lars Chittka wanted to discover whether bumblebees could learn to avoid these crab spiders. Their study, funded by the Natural Environment Research Council and published in the journal Current Biology, shows how a run-in with a spider affected the bees’ foraging patterns.

ROBOTIC CRAB SPIDERS

Dr Ings and his team allowed a colony of bumblebees {Bombus terrestris) to forage in a meadow of artificial flowers in a ‘flight arena’ which contained ‘robotic’ crab spiders. Some of the spiders were well hidden, others were highly visible.

Whenever a bee landed on a ‘flower’ which contained a robot spider, the spider ‘caught’ the bee by trapping it briefly between two foam pincers, before then setting it free to continue foraging. Video of the bees can be seen at www.qmul.ac.uk/video/

Untitled-1(2)-2

The trapping sequence

The team used 3D tracking software to follow the bees’ movements and found that the bees which were caught by a camouflaged ‘spider’ slowed down their subsequent inspection flights. Although they lost valuable foraging time by slowing down, they were more likely to accurately detect whether there was a hidden crab spider present.

ONCE BITTEN…

In addition, the bees which had already been caught a few times the day before by the hidden spiders behaved as if they saw spiders where there were none, ie, they rejected foraging opportunities on safe flowers ‘just in case’ and were more wary than bees which had been caught by the more conspicuous spiders.

Dr Ings commented: ‘Surprisingly, our findings suggest that there is no apparent benefit to the spider in being camouflaged, at least in terms of prey capture rates. Spider camouflage didn’t increase the chances of a bumblebee being captured, or reduce the rate at which the bees learnt to avoid predators. However, our results did show that the bees which encountered camouflaged spiders were worse off in terms of reduced foraging efficiency’. |p

REFERENCE

Speed accuracy tradeoffs and false alarms in bee responses to cryptic predators, Current Biology, 4 September 2008.

This entry was posted in Previous Articles. Bookmark the permalink. Both comments and trackbacks are currently closed.
  • Bee Craft Magazine - Prices
    Beekeeping Information Centre
    Photo Competition 2014
    starting out Microscopy Your Ad Here Bee Craft Adverts
  • bkids