[APWG] Invasive scale killing native cycads in Guam

[Plant Conservation]

Please respond directly to Anne Brooke (Anne_Brooke at fws.gov) if you have
any suggestions or can help with this issue.

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From: "Brooke, Anne P." <Anne_Brooke at fws.gov> on Fri, 3 Jun 2005
To: "John Kress (E-mail)" <Kress.John at NMNH.SI.EDU>
Subject: cycad death on Guam

Hi John,

I am writing you to make you aware of and ask for help with an ongoing
ecological disaster taking place on Guam with the potential to spread to
other Micronesian islands that are home to an indigenous cycad, Cycas
micronesica.  A diaspidid scale, Aulocapsis yasumatsui Takagi, was
detected on Guam in December, 2003 on an ornamental cycad, Cycas revoluta,
in front of the Hyatt Regency Hotel in Tumon Bay, a resort area.
Introduced to Florida on ornamental cycads, the scale traveled to Hawaii
from where it then traveled to Guam on an ornamental cycad imported by a
local nursery. In the next two years it spread throughout the northern 2/3
of Guam, infesting and killing both ornamental and indigenous cycads.  C.
micronesica, the indigenous cycad unique to Micronesia, seems particularly
susceptible, with mortality rates of 100% in infested areas. I've
attached a couple of photos of infested C. micronesica to this email.
These trees are over 100 years old, and have survived the Spanish American
War, two World Wars, inumerable earthquakes, typhoons and tropical storms,
and waves of human encroachment.  The scale may be their demise.  We have
imported a coccinellid from Maui, Rhizobius lophanthae, which is
established in northern Guam and is being released elsewhere on the island
as population density increases.  We don't expect R. lophanthae to be able
to control the scale on its own and have begun procedures to import a
parasitoid present in Florida (Coccobius fulvus), where the scale was
originally introduced into the US.  However, this parasitoid does not
control the scale, and there are some efforts underway to explore in China
where the scale apparently originated from.

The problem is that the infestation is spreading so fast on Guam that we
risk losing the entire population of 1.5 million trees to A. yasumatsui
before enough suitable biocontrol agents are found and released.  Unlike
Florida and Hawaii where the only cycads present are introduced
ornamentals, the bulk of Guam's cycads are indigenous, are the dominat
forest tree on the island, and appear more susceptible to the scale than
C. revoluta.  To compound the problem, nurseries on Guam ship plants to
other Micronesian islands that have C. micronesica, so we fear that the
scale will soon make its way throughout Micronesia.  We may be witnessing
an invasive species effect comparable to that of the brown treesnake on
Guam's birds a few years ago, though cycads are not so attractive to most
as cute little island birds.  We could lose every C. micronesica in Guam
and perhaps in the other islands within a few more years.  We have
initiated contacts with USFW, USFS and others to alert them of the problem
and solicit assistance, but so far haven't connected.  There are efforts
underway to have C. micronesica declared an endangered species, but I am
not sure these will fly given that curently the scale is only on Guam.  We
desparately need emergency funding to obtain and release biocontrol agents
on Guam, and to hopefully prevent or prepare for its spread to other
islands.

There is a chemical control scheme that works using a systemic or
interlamellar insecticides such as acephate or imidacloprid, following
trimming and burning of infested leaves, but this is impractical given the
number and inaccessibility of most of Guam's cycads.

We would greatly appreciate any help in locating emergency funding. We are
in contact with ARS scientists in Ft. Pierce, FL regarding biocontrol
activities.  We are concerned that since the scale is of relatively
limited economic importance in Florida and Hawaii where all cycads are
introduced ornamentals, a pest on Micronesian cycads may not generate much
interest. But in terms of its ecological impact in the US insular
territories and former territories in Micronesia, it is huge.

Thanks
Anne

Anne Brooke, Ph.D.
Wildlife Biologist
Guam National Wildlife Refuge
POB 8134, MOU-3
Dededo, Guam 96929 USA
brookea at guam.navy.mil
Anne_Brooke at fws.gov
671-339-7051