Data from: The effect of trap colour and trap-flower distance on prey and pollinator capture in carnivorous Drosera species

1. The functional features of carnivorous plants’ traps have been mostly
interpreted as adaptations to capture prey. Carnivorous plants that feed
on insects, however, run the risk that increasing trapping effectiveness
might in turn reduce reproductive success through capture of pollinators.
Such a pollinator–prey conflict might play an important role in the
evolution of trap features. In carnivorous plants with sticky leaves (e.g.
Drosera, Pinguicula), both spatial distance between traps and flowers and
their visual signals (e.g. colour, display size) likely play a role in
attracting prey but it has also been suggested that they affect the risk
of potential pollinators landing on a trap. It has been reported, for
example, that red pigmentation in carnivorous plants may lure insect prey
to traps. This idea remains controversial, however, because colour vision
of most insects does not extend very far into the red part of the
spectrum. 2. We tested an alternative hypothesis, namely that red
pigmentation of the trapping leaves may reduce the risk of a
pollinator–prey conflict. Experiments were conducted in a natural habitat
of Drosera arcturi and D. spatulata in the Southern Alps of New Zealand.
Using sticky model traps similar in shape to Drosera leaf traps and
flowers, we investigated the effect of colour (green vs. red vs. white)
and flower-trap distance (flower stalk length and leaf arrangement, that
is upright as in D. arcturi vs. flat ground rosette as in D. spatulata) on
composition and abundance of insects landing and being trapped. 3.
Flower-trap distance had no significant effect on the risk of pollinators
being trapped but model flowers higher above the ground received more
pollinator landings. Across all model traps, the number of trapped
potential pollinators was significantly lower in traps with red leaves
compared to green ones. 4. The results suggest that the typical red
pigmentation of the trapping leaves in Drosera may be a way to protect
pollinators from being attracted and captured. However, our data also
suggest that pollinator protection via red traps may come with a trade-off
since total prey capture was also significantly reduced.