Aulacaspis yasumatsui Delivers a Blow to International Cycad Horticulture

Marler, Thomas E.; Lindström, Anders J.; Watson, Gillian W.

doi:10.3390/horticulturae7060147

Cited by 14 publications

(24 citation statements)

References 83 publications

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“…The enactment of this plan carries the potential to serve as an example for global cycad conservation approaches wherever invasive species are among the threats. For example, Cycas taitungensis Shen, Hill, Tsou & Chen is the second cycad species that has been threatened within its endemic range by an A. yasumatsui invasion [20]. Although the pollinator of C. taitungensis is not known to date, the influence of A. yasumatsui on C. taitungensis reproductive biology likely has parallels to the Guam case study.…”

Section: Discussionmentioning

confidence: 94%

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Aulacaspis yasumatsui Invasion Reduced Cycas micronesica Microstrobilus Size and Pollinator Brood Site Competence

Marler

Terry

2021

Insects

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Aulacaspis yasumatsui Takagi invaded Guam in 2003, and the influence on survival and demography of the host Cycas micronesica K.D. Hill population has been well-studied. To more fully understand how A. yasumatsui has threatened the host cycad species, we determined the microstrobilus size and number of pollinators per microstrobilus from 2001 to 2021. The microstrobilus height and diameter were measured directly, and the volume was calculated. Microstrobili were 58 cm in height, 13 cm in diameter, and 4740 cm3 in volume prior to direct A. yasumatsui infestations. Microstrobili decreased in size immediately after direct infestations by A. yasumatsui, and then began to slowly increase in size until 2021. For example, the volume was 24% of pre-invasion volume in 2007, and was 57% of pre-invasion volume in 2021. Microstrobili were harvested; then, the number of pollinator pupae were counted after an incubation period. Pollinator pupae counts per microstrobilus declined to 66% of pre-invasion levels by 2007 and have remained similarly constrained through 2021. Our results revealed that A. yasumatsui damage to the host C. micronesica population is not limited to attrition of the extant plant population, but also includes a loss in male reproductive effort and the risk of coextinction of the insular pollinator.

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Section: Discussionmentioning

confidence: 94%

“…The invasion of Guam by A. yasumatsui was predicted in 2000 [20], occurred in 2003 [2], and then devastated the population of the native host tree C. micronesica [6]. The invasion of this nonnative specialist armored scale has generated numerous negative outcomes at the organismal and population levels [3,[6][7][8][9][10][11][12].…”

Section: Discussionmentioning

confidence: 99%

Aulacaspis yasumatsui Invasion Reduced Cycas micronesica Microstrobilus Size and Pollinator Brood Site Competence

Marler

Terry

2021

Insects

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“…One of these pathogens is the Cycad Aulacaspis Scale (CAS) (Aulacaspis yasumatsui) Takagi, which was first discovered in 1972 in Thailand on Cycas revoluta (Takagi, 1977). Since its discovery, CAS has spread to 39 countries and is now considered the single most important threat to natural cycad populations by the International Union for the Conservation of Nature Cycad Specialist Group (IUCN) (IUCN, 2005;Marler et al, 2021). Although CAS naturally occurs on Cycas revoluta, it has been recorded on 21 different cycad species from eight genera (Bowenia, Ceratozamia, Dioon, Encephalartos, Macrozamia, Microcycas, Stangeria, and Zamia).…”

Section: Pathogensmentioning

confidence: 99%

The potential impacts of climate change on ex situ conservation options for recalcitrant-seeded species

Fernández

León‐Lobos

Contreras

et al. 2023

Front. For. Glob. Change

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Recalcitrant seeds are characterized by desiccation and freezing sensitivity, and short storage longevity. These physiological attributes obviate their ex situ conservation in conventional seed banks, where seeds are stored dry at sub-zero temperatures (typically, 15% relative humidity and –20°C) for extended periods of time. Propagation of plants for field collections (e.g., botanical gardens, nurseries, and arboretums) is a valuable ex situ conservation option. However, these collections are relatively costly, require high maintenance, preserve limited genetic diversity and/or are directly exposed to biotic (e.g., pests) and abiotic (e.g., climatic) threats. Therefore, recalcitrant-seeded (RS) species are dependent on cryopreservation for their safe and long-term ex situ conservation. Different explant sources such as whole seeds, zygotic embryos, dormant buds, shoot tips, and pollen, can be used for plant propagation of RS species in field collections as well as for their cryopreservation. The success of the propagation or the cryopreservation of these explants often depends on their developmental status, vigor, and/or tolerance to desiccation and chilling/freezing. These attributes are modulated by the environment where the donor plant grows and we hypothesize that climate change, by affecting these biological attributes, would impact the success of explant propagation and cryopreservation. To support this hypothesis, we have reviewed how temperature changes and drought, the two main climate change scenarios, affect the main biological attributes that are directly involved in the success of ex situ conservation of tropical and temperate RS species. In general, increases in temperature and drought will negatively affect plant development in field collections and the quality of the explants used in cryopreservation. Consequently, field collections of RS species may need to be moved to more suitable places (e.g., higher latitudes/altitudes). Additionally, we may find a reduction in the success of cryopreservation of RS species germplasm directly harvested from field collections. However, we cannot always generalize these effects for all species since they often depend on the origin of the species (e.g., tropical and temperate species tend to respond to climate change differently), the genotype, the adaptive genetic potential of each population, and the severity of the environmental change. On the other hand, the increase in temperatures and water stress in donor plants at high-latitude areas and also some tropical environments may favor the production of seeds and seedlings better adapted to drying, and hence, increase the success of plant propagation and zygotic embryo cryopreservation.

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“…The armored scale A. yasumatsui has been invading new territories in recent years to threaten native and cultivated host cycad plants [1]. The invasion that has been most studied was the invasion of Guam in 2003 [2].…”

Section: Introductionmentioning

confidence: 99%

Direct Aulacaspis yasumatsui Infestation of Pre-Harvest Cycas Seeds Reduces Germination and Performance of Seedlings

Marler

2021

Horticulturae

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The invasion of numerous countries by the armored scale Aulacaspis yasumatsui Takagi has caused widespread mortality of host Cycas species. Few studies have looked at reproductive biology responses of host plants to the herbivore. This study was conducted to determine the influence of direct Cycas seed integument infestation of A. yasumatsui on germination and seedling performance. An observational study in a Tinian ex situ Cycas micronesica K.D. Hill garden revealed that germination percentage was reduced two-thirds by heavy pre-harvest integument infestation, and more than half of the seedlings from infested seeds died in the nursery. Multi-year mortality of plants was six times greater for plants from habitats with infested seeds than for plants from minimally infested habitats. Stem height of nine-year-old plants from habitats with infested seeds was 64% of that of plants from habitats with un-infested seeds. A controlled study in a Philippine ex situ C. micronesica and Cycas edentata de Laub. garden corroborated these findings. Germination of infested seeds was about 30% of that for un-infested seeds. Seedling mortality in the nursery following experimental infestation of seed integuments with A. yasumatsui during seed maturation was about 50%, but was minimal for seedlings from un-infested seeds. These results indicate that limitations in regeneration and recruitment of host Cycas plants following A. yasumatsui herbivory may be partly due to the influence of direct seed infestations. Conservationists may use this new knowledge to improve in situ seed selection criteria and use prophylactic treatments to ensure lack of integument infestations for ex situ gardens.

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Aulacaspis yasumatsui Delivers a Blow to International Cycad Horticulture

Cited by 14 publications

References 83 publications

Aulacaspis yasumatsui Invasion Reduced Cycas micronesica Microstrobilus Size and Pollinator Brood Site Competence

Aulacaspis yasumatsui Invasion Reduced Cycas micronesica Microstrobilus Size and Pollinator Brood Site Competence

The potential impacts of climate change on ex situ conservation options for recalcitrant-seeded species

Direct Aulacaspis yasumatsui Infestation of Pre-Harvest Cycas Seeds Reduces Germination and Performance of Seedlings

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