Colouration in crab spiders: substrate choice and prey attraction

Area of Science:

• Ecology
• Animal Behavior
• Vision Science

Background:

• Crab spiders (Thomisus spectabilis) can change color (yellow/white) to ambush pollinating insects like honeybees (Apis mellifera).
• Traditional assumption: spiders match flower color for crypsis (camouflage).
• This study investigates spider color matching and its effect on bee behavior using bee vision knowledge.

Purpose of the Study:

• To test the assumption that crab spiders change color to match flowers for camouflage.
• To determine if spider body color influences flower selection by spiders.
• To analyze how spider-flower color combinations affect honeybee landing preferences.

Main Methods:

• Field observations of spider color and flower association (yellow/white daisies).
• Laboratory experiments testing spider flower preference.
• Behavioral experiments assessing honeybee landing choices on flowers with and without spiders, considering bee visual perception.

Main Results:

• Yellow spiders exclusively on yellow daisies; white spiders on yellow and white daisies.
• Yellow spiders preferred yellow flowers; white spiders showed no significant flower preference.
• Honeybees' responses were not predicted by classical crypsis; bees were attracted to white spiders on white flowers due to UV reflectance contrast.
• Bees preferred flowers with white spiders (on white or yellow) and were indifferent to yellow spiders on yellow flowers, but rejected yellow spiders on white flowers.

Conclusions:

• Thomisus spectabilis adaptively select flower backgrounds matching their body color.
• This selection deceives honeybees or fails to deter them, challenging traditional crypsis assumptions.
• Spider coloration and flower background interact with bee vision to influence predator-prey interactions.