Abstract

Critical for conserving endangered orchids is identifying their pollinators and their distribution. Caladenia xanthochila is an endangered orchid that has floral traits characteristic of pollination by food foraging insects. We identified the pollinator(s), mechanisms of attraction and the presence of pollinators at natural, existing and potential translocation sites. Furthermore, we quantified pollination success at translocation sites and investigated the effect of rainfall on pollination success over 19 years at a natural site. We clarify if sharing of pollinators occurs with closely related species by comparing the CO1 barcoding region of the pollinators' DNA. Caladenia xanthochila was pollinated by a single species of thynnine wasp, Phymatothynnus aff. nitidus. Caladenia xanthochila produced 27.0 & mu;g & PLUSMN; 7.1 sucrose on the labellum, while pollinators vigorously copulated with glandular clubs on the sepal tips, suggestive of a mixed pollination system. Pollination success of C. xanthochila was 7.6 & PLUSMN; 1.5% SE at the natural site and 16.1 & PLUSMN; 3.6% SE across the translocation sites. Furthermore, hand pollinations demonstrated that pollination was pollen limited. Pollination success was significantly related to average rainfall during the growth phase of the orchid (P < 0.001). Potential translocation sites for C. xanthochila were limited, with four of six surveyed lacking the pollinator. We found evidence for cryptic species of Phymatothynnus, with C. xanthochila pollinators being unique amongst the orchids studied. We recommend hand pollinations at translocated and remnant wild populations to boost initial recruitment. The evidence for cryptic species of pollinators further highlights the need for accurate identification of pollinators.

Keywords

Orchidaceae; Caladenia; Pollination; Nectar; Cryptic species; Translocation; Conservation

Published in

Plant Ecology
2023, Volume: 224, number: 8, pages: 715-727
Publisher: SPRINGER

SLU Authors

• Bohman, Björn

  • Department of Plant Protection Biology, Swedish University of Agricultural Sciences
    
  • Australian National University
  • University of Western Australia

Associated SLU-program

SLU Plant Protection Network


UKÄ Subject classification

Botany
Ecology


More information

Correction in: Plant Ecology, 2023, Early Access, DOI: 10.1007/s11258-023-01340-2


Publication identifier

DOI: https://doi.org/10.1007/s11258-023-01334-0

Permanent link to this page (URI)

https://res.slu.se/id/publ/122986