CAN POLLINATOR TRANSPLANTATION INCREASE REPRODUCTIVE SUCCESS IN POPULATIONS OF THE THREATENED ORCHID, SPIRANTHES DILUVIALIS?

Authors: Tepedino, Vincent; SIPES, SEDONIA - UTAH STATE UNIV. BIOLOGY

Submitted to: Ecological Restoration
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/1/2000
Publication Date: N/A
Citation: N/A

Interpretive Summary: This brief report describes an effort to increase the fruit and seed production of a species of orchid listed as threatened under the Endangered Species Act. The Ute ladies' tresses population of interest, in Brown's Park, Utah, has consistently shown low fruit and seed production throughout our several years of monitoring since 1991. This population is also unusual in that pollinator populations are very low, and one species of native bee pollinator that is important at other locations is absent here. We are trying to improve reproduction at Brown's Park by importing that pollinator, Anthophora terminalis, from other areas in the Intermountain West. Thus far, we have transplanted a small number of twig-nests with bees in them into Brown's park, and the bees have emerged and nested successfully. Populations however remain low.

Technical Abstract: Spiranthes diluvialis, Ute ladies' tresses, is a rare, riparian orchid endemic to Utah, Colorado, Wyoming, Idaho, and Montana. It is listed as threatened under the Endangered Species Act. Reproduction by this species is variable from population to population. While most populations show over 60% fruit set, one, at Brown's Park, Utah, is consistently below 30%, and sometimes as low as 3%. The reason for this very low fruit and seed production appears to be related to the paucity of pollinators at the Brown's Park site. In particular, a twig-nesting species of native bee, Anthophora terminalis, seems to be completely absent at Brown's Park though it is frequently abundant, and an important pollinator, at other more successful populations. Over the past two years we have been trying to obtain immature individuals of this bee in their nests, and transplant them to Brown's Park. We are beginning to see signs of success. We have made several successful transplants and the transplanted bees have emerged and nested successfully, though in small numbers. We are optimistic about future efforts.