Observed plant recovery of the endangered Cycas micronesica populations on the island of Guam: plant resistance or biocontrol

The island of Guam’s only gymnosperm and historically one of the island’s most abundant trees, Cycas micronesica, has been devastated by high mortality due primarily to the armoured scale Aulacaspis yasumatsui. This cycad-specific scale pest invaded Guam in 2003 and, in only a few years, this pest c...

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Main Authors: Irene Terry, Thomas Marler
Format: Article
Language:English
Published: Pensoft Publishers 2024-11-01
Series:Research Ideas and Outcomes
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Online Access:https://riojournal.com/article/131260/download/pdf/
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author Irene Terry
Thomas Marler
author_facet Irene Terry
Thomas Marler
author_sort Irene Terry
collection DOAJ
description The island of Guam’s only gymnosperm and historically one of the island’s most abundant trees, Cycas micronesica, has been devastated by high mortality due primarily to the armoured scale Aulacaspis yasumatsui. This cycad-specific scale pest invaded Guam in 2003 and, in only a few years, this pest caused over 90% mortality to maturing trees and 100% mortality to seedlings. In 2015, C. micronesica was listed under the United States Endangered Species Act. Continuous surveillance of tree mortality throughout the island showed extreme decline in health until recent surveys have demonstrated that there has been improved tree health with little evidence of leaf herbivory on some remaining trees. Suggested explanations for this observed reduction in scale herbivory include some form of resistance in the surviving trees or a biocontrol agent (or several agents) that previously existed or has been introduced unintentionally and is controlling the scale to a greater degree. A combination of resistance and biocontrol are possibly both involved. We discuss in depth these possibilities and then propose experimental approaches that will help resolve this question.
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spelling doaj-art-5576cddc350c497bb04840bbeb9761d32024-11-17T08:32:31ZengPensoft PublishersResearch Ideas and Outcomes2367-71632024-11-011011010.3897/rio.10.e131260131260Observed plant recovery of the endangered Cycas micronesica populations on the island of Guam: plant resistance or biocontrolIrene Terry0Thomas Marler1University of UtahPhilippine Native Plants Conservation Society Inc., Ninoy Aquino Parks and WildlifeThe island of Guam’s only gymnosperm and historically one of the island’s most abundant trees, Cycas micronesica, has been devastated by high mortality due primarily to the armoured scale Aulacaspis yasumatsui. This cycad-specific scale pest invaded Guam in 2003 and, in only a few years, this pest caused over 90% mortality to maturing trees and 100% mortality to seedlings. In 2015, C. micronesica was listed under the United States Endangered Species Act. Continuous surveillance of tree mortality throughout the island showed extreme decline in health until recent surveys have demonstrated that there has been improved tree health with little evidence of leaf herbivory on some remaining trees. Suggested explanations for this observed reduction in scale herbivory include some form of resistance in the surviving trees or a biocontrol agent (or several agents) that previously existed or has been introduced unintentionally and is controlling the scale to a greater degree. A combination of resistance and biocontrol are possibly both involved. We discuss in depth these possibilities and then propose experimental approaches that will help resolve this question.https://riojournal.com/article/131260/download/pdf/<i>Aulacaspis yasumatsui</i>biological control
spellingShingle Irene Terry
Thomas Marler
Observed plant recovery of the endangered Cycas micronesica populations on the island of Guam: plant resistance or biocontrol
Research Ideas and Outcomes
<i>Aulacaspis yasumatsui</i>
biological control
title Observed plant recovery of the endangered Cycas micronesica populations on the island of Guam: plant resistance or biocontrol
title_full Observed plant recovery of the endangered Cycas micronesica populations on the island of Guam: plant resistance or biocontrol
title_fullStr Observed plant recovery of the endangered Cycas micronesica populations on the island of Guam: plant resistance or biocontrol
title_full_unstemmed Observed plant recovery of the endangered Cycas micronesica populations on the island of Guam: plant resistance or biocontrol
title_short Observed plant recovery of the endangered Cycas micronesica populations on the island of Guam: plant resistance or biocontrol
title_sort observed plant recovery of the endangered cycas micronesica populations on the island of guam plant resistance or biocontrol
topic <i>Aulacaspis yasumatsui</i>
biological control
url https://riojournal.com/article/131260/download/pdf/
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AT thomasmarler observedplantrecoveryoftheendangeredcycasmicronesicapopulationsontheislandofguamplantresistanceorbiocontrol