Alien insect attacking Guam's native flora
Alien insect attacking Guam's native flora
- guampdn.com
The king sago is a dominant member of Guam's urban landscape and is currently under attack by a newly introduced insect pest.
Guam's king sago plants are under attack by a newly introduced scale insect that has been killing plants in Florida and Hawaii for years.
"We began noticing an outbreak of a very small white insect called 'scale' on these plants a few months ago," says Aubrey Moore, an entomologist studying invasive insects with the University of Guam. "Some plants were so heavily infested that it looked like they were covered with white spray paint."
At that time, the largest population of the pest was found in the Tumon area and in Barrigada Heights.
This new insect pest is a nightmare for landscape managers, and recent developments indicate it will likely become an ecological nightmare.
The first of these developments occurred two weeks ago when the university received positive identification of the insect pest.
"We learned that the scale outbreak on Guam is due to two species not previously detected on Guam -- the Asian cycad scale and the Magnolia white scale," Moore says.
The white scale becomes so dense on the lower side of king sago leaves that the leaves appear to be covered with a white crust.
Both of these scale insects have been serious pests on king sago in the Florida and Hawaii landscapes for years.
The Asian cycad scale can kill a mature plant within a year of the initial infestation in the Florida landscape. Without intervention, the lovely king sago that dominate the commercial and residential landscapes on Guam are at risk of death.
Residents and tourists already have seen hundreds of attractive king sago become unsightly. Some king sago look like dead stumps because landscape managers trying to cope with the alien pest have pruned away the entire leaf crown.
Observations from Florida and Hawaii indicate that Guam's own native fadang is known to be highly susceptible to this alien insect pest as well. Fadang is a cycad species that inhabits Guam and surrounding islands, and is closely related to the king sago.
"We have been growing plants of Guam's native cycad for many years," says Jody Haynes, cycad biologist for Montgomery Botanical Center in Miami, Fla. "Because the Asian cycad scale was accidentally introduced to the Miami area prior to 1996, we have been able to observe the interactions between this insect and Guam's cycad plants for many years."
These observations indicate that Guam's fadang is as susceptible as the king sago to being attacked by this scale.
"This may be the first time an alien pest has the potential to wipe out a native species of cycad," says Greg Holzman, former curator of cycads for the National Tropical Botanical Garden on the island of Kauai. "If a Guam cycad plant becomes infested with this scale and nothing is done, the plant will die quickly."
The Asian cycad scale migrated to Oahu about five years ago, undoubtedly on king sago nursery plants that were imported from Florida. Holzman observed the death of a 10-year-old fadang plant on Oahu shortly after the plant became infested with the new scale pest.
Perhaps the most distressing observation about the identification of this new insect pest is that its introduction to Guam was completely avoidable.
I wrote an article about this scale insect in the Pacific Daily News on Feb. 13, 2000. In that article, I pointed out the threat to Guam's fadang population and suggested that local nurseries and landscape companies stop importing king sago nursery plants voluntarily as the only sure plan for keeping this cycad-killing insect out of Guam's environment. But the avoidable has become the inevitable, and the inevitable is now poised to threaten one of our own native plant species.
Thomas Marler is a professor with the College of Natural and Applied Sciences, University of Guam.
- guampdn.com
The king sago is a dominant member of Guam's urban landscape and is currently under attack by a newly introduced insect pest.
Guam's king sago plants are under attack by a newly introduced scale insect that has been killing plants in Florida and Hawaii for years.
"We began noticing an outbreak of a very small white insect called 'scale' on these plants a few months ago," says Aubrey Moore, an entomologist studying invasive insects with the University of Guam. "Some plants were so heavily infested that it looked like they were covered with white spray paint."
At that time, the largest population of the pest was found in the Tumon area and in Barrigada Heights.
This new insect pest is a nightmare for landscape managers, and recent developments indicate it will likely become an ecological nightmare.
The first of these developments occurred two weeks ago when the university received positive identification of the insect pest.
"We learned that the scale outbreak on Guam is due to two species not previously detected on Guam -- the Asian cycad scale and the Magnolia white scale," Moore says.
The white scale becomes so dense on the lower side of king sago leaves that the leaves appear to be covered with a white crust.
Both of these scale insects have been serious pests on king sago in the Florida and Hawaii landscapes for years.
The Asian cycad scale can kill a mature plant within a year of the initial infestation in the Florida landscape. Without intervention, the lovely king sago that dominate the commercial and residential landscapes on Guam are at risk of death.
Residents and tourists already have seen hundreds of attractive king sago become unsightly. Some king sago look like dead stumps because landscape managers trying to cope with the alien pest have pruned away the entire leaf crown.
Observations from Florida and Hawaii indicate that Guam's own native fadang is known to be highly susceptible to this alien insect pest as well. Fadang is a cycad species that inhabits Guam and surrounding islands, and is closely related to the king sago.
"We have been growing plants of Guam's native cycad for many years," says Jody Haynes, cycad biologist for Montgomery Botanical Center in Miami, Fla. "Because the Asian cycad scale was accidentally introduced to the Miami area prior to 1996, we have been able to observe the interactions between this insect and Guam's cycad plants for many years."
These observations indicate that Guam's fadang is as susceptible as the king sago to being attacked by this scale.
"This may be the first time an alien pest has the potential to wipe out a native species of cycad," says Greg Holzman, former curator of cycads for the National Tropical Botanical Garden on the island of Kauai. "If a Guam cycad plant becomes infested with this scale and nothing is done, the plant will die quickly."
The Asian cycad scale migrated to Oahu about five years ago, undoubtedly on king sago nursery plants that were imported from Florida. Holzman observed the death of a 10-year-old fadang plant on Oahu shortly after the plant became infested with the new scale pest.
Perhaps the most distressing observation about the identification of this new insect pest is that its introduction to Guam was completely avoidable.
I wrote an article about this scale insect in the Pacific Daily News on Feb. 13, 2000. In that article, I pointed out the threat to Guam's fadang population and suggested that local nurseries and landscape companies stop importing king sago nursery plants voluntarily as the only sure plan for keeping this cycad-killing insect out of Guam's environment. But the avoidable has become the inevitable, and the inevitable is now poised to threaten one of our own native plant species.
Thomas Marler is a professor with the College of Natural and Applied Sciences, University of Guam.
posted by DP at 2:30 PM
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