Data from: Identification of pollinators of lesser twayblade (Neottia cordata L.) with DNA barcoding reveals strong links with pine forest-related fauna

Many European terrestrial orchids are in decline. To curb this negative
trend and preserve remaining populations, more ecological knowledge is
needed. Surprisingly little is known yet about the identity and efficiency
of pollinators of Lesser Twayblade (Neottia cordata), a small terrestrial
orchid species associated with pine trees through joint mycorrhizae. We
identified its small and inconspicuous pollinators with DNA barcoding and
assessed its fruit set with the help of observations submitted to various
nature platforms. We caught pollinators on Terschelling in The Netherlands
during the flowering season of 2013 and 2014. Insects were identified with
28S and COI sequences obtained from both fresh and museum-preserved
material identified by specialists. Several pollinators were detected,
belonging to either parasitoid wasps (Braconidae) and spider wasps
(Pompilidae), active during sunny periods, or fungus gnats (Mycetophilidae
and Sciaridae), active during overcast conditions. Combined pollinator
efforts resulted in a continuous average fruit set above 70% in Europe
over the past 135 years. The parasitoid wasps were identified as Bracon
pineti and Blacus sp., which strongly depend on pine trees for their prey.
The fungus gnats were identified as Austrosciara hyalipennis, Trichosia
lengersdorfi, Allodia lugens and Phronia forcipata. All four species are
known to deposit their eggs in the vicinity of fruiting bodies of Cone
Caps (Strobilurus stephanocystis), mushrooms growing on pine cones, as
their larvae feed on the fungi. Priocnemis pertubator and Anoplius
viaticus (Pompilidae) are also important pollinators. Results obtained
show that Lesser Twayblade is even more intricately linked to pine forest
ecosystems than previously thought. Management of growth sites of N.
cordata should be tailored towards preserving pine tree forests with plots
that are constantly being rejuvenated to generate young pine trees and
prevent succession towards birch-oak forests. Such forests not only
provide mycorrhizal fungi and layers of needle litter needed for
germination and development of the seeds of this orchid but also
pinewood-decaying fungi that provide egg deposition sites and food for its
pollinators.