Mosquito eradication programme begins
Media Release
4 May 2006
Mosquito eradication programme begins
The eradication programme to rid Kaipara Harbour of a type of unwanted Australian mosquito, the southern salt marsh mosquito, has been revived with the discovery of three adult mosquitoes and 19 larvae.
Following recent wet events in the Kaipara Harbour (a series of king tides followed by rainfall), surveillance teams found small numbers of southern salt marsh mosquitoes at two different locations in the southern Kaipara harbour.
"As soon as the samples were found eradication treatment began at the sites," said JR Gardner, Deputy Chief Technical Officer (Health).
"It is a surprise for the Kaipara eradication programme to find these 'tail enders' at this point in time. The next few weeks are important as this will determine if there are other infested areas."
"We are responding by maintaining surveillance throughout the entire eradication zone. Officials and technical experts are analysing the collection data in order that the planning for dealing with this event will meet the rigorous science-based standards maintained throughout the programme," Mr Gardner added.
The active treatment phase of Kaipara Harbour has been completed but the area remains under surveillance.
Q &
A: What is the southern salt marsh mosquito? The
southern salt marsh mosquito (Ochlerotatus camptorhynchus)
is a mosquito species found in coastal areas of southern
Australia. It was first discovered at Napier, New Zealand
in December 1998.
What is the health threat from the
southern salt marsh mosquito? The mosquito is an
aggressive day biter with the potential to cause
significant nuisance effects for people, livestock and
birds. It is a confirmed vector of Ross River Virus (RRV)
in southwest Western Australia. If the southern salt marsh
mosquito population is left unchecked, future risks include
the introduction of RRV to susceptible human populations and
an epidemic of the disease. What monitoring has occurred
in the area in the past two years? Continuous monitoring
has been carried out throughout the Kaipara Harbour since
June 2004. Where were the mosquitoes found? The
mosquito specimens were found at a site approximately 3.5
kilometers northwest of Parakai and at two sites some 13
kilometers north of Helensville. The specimens found were
adults and larvae. Larvae are mosquitoes in the wriggler
stage of the lifecycle when the mosquito lives in
water. Have there been any other finds of these mosquitoes
since June 2004? A single adult was discovered close to
Shelly Beach in early November 2005. Subsequently, several
larvae were found at a site 13 kilometers north of
Helensville at a farm near the Makarau River mouth. These
?tailend? findings initiated an immediate treatment
response. How big is the initial infestation area (size
of area)? An area of up to 300 hectares may need to be
treated to kill any other mosquitoes present. How
successful are the eradication programmes? The eradication
programmes in Napier, Haumoana, Mahia, Porangahau,
Tairawhiti, Mangawhai and Whitford have been completed and
there have been no further finds of the Southern Saltmarsh
Mosquito in these areas. The active treatment phase of the
Kaipara eradication programme has been completed and this
area is in phase three (surveillance) of the eradication
programme. Until this latest find, with the exception of the
findings late last year, no larvae have been detected in the
greater Kaipara Harbour since February 2004. The Wairau
eradication plan is being fully implemented over an
estimated 1200 hectares of saltmarsh in the Wairau lagoons
and Grassmere areas in Marlborough. The full treatment
phase of the eradication programme began in December 2004
and is expected to continue until March or April 2006, when
it will move into the surveillance phase of eradication. A
small site at Whangaparaoa was discovered in January 2004,
with more mosquito larvae found in May
2005. ENDS