Department of Health is a Smoke Free Workplace Groote Eylandt exotic mosquito survey report 19 to 21 March 2014 William Pettit and Nadine Copley Medical Entomology Centre for Disease Control Department of Health Northern Territory Government April 2017
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Groote Eylandt survey Mar 2014 · 2019-04-04 · GEMCO in Alyangula since July 1981. The program was suspended in October 1983 but resumed in February 1995, with fortnightly adult
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Department of Health is a Smoke Free Workplace
Groote Eylandt exotic mosquito survey report
19 to 21 March 2014
William Pettit and Nadine Copley
Medical Entomology
Centre for Disease Control
Department of Health
Northern Territory Government
April 2017
DEPARTMENT OF HEALTH
Page 2 Department of Health is a Smoke Free Workplace
Medical Entomology, Centre for Disease Control
Department of Health, Northern Territory 2017
This publication is copyright. The information in this report may be freely copied and distributed for
• non-profit purposes such as study, research, health service management and public information subject to the inclusion of an acknowledgment of the source. Reproduction for other purposes requires the written permission of the Chief Executive of the Department of Health, Northern Territory.
An electronic version is available at: http://digitallibrary.health.nt.gov.au/prodjspui/
General enquiries about this publication should be directed to:
Nina Kurucz
Director
Medical Entomology CDC Department of Health 7PO Box 41326, NT 0811
Phone:
(08) 8922 8901
Facsimile:
(08) 8922 8820
DEPARTMENT OF HEALTH
Page 3 Department of Health is a Smoke Free Workplace
Background
Alyangula is a mining town, located on Groote Eylandt, with approximately 400 properties. The town supports about 1400 residents who are mainly Groote Eylandt Mining Corporation (GEMCO) employees or employees of support services.
Routine adult mosquito monitoring, using CO2 baited EVS traps, has been conducted by GEMCO in Alyangula since July 1981. The program was suspended in October 1983 but resumed in February 1995, with fortnightly adult mosquito trapping carried out by GEMCO until January 2014. The most recent adult mosquito trapping conducted by GEMCO was on 21/01/14. Although there is no current capacity to continue the program, it is expected that GEMCO will resume routine fortnightly adult mosquito trapping in the very near future.
Routine ovitrap surveillance has been conducted in Alyangula since July 1998, with a program break of three years between 2000 and 2003. The ovitrap program detected the Aedes aegypti (dengue mosquito) incursion on Groote Eylandt when an ovitrap at the wharf was found to contain larvae of this exotic species on 20/10/2006. The subsequent elimination program, managed by the NT Department of Health (DoH), found Ae. aegypti breeding on 93 properties in Alyangula and on one property in Angurugu. The program was successful in eliminating Ae. aegypti from Groote Eylandt and concluded in April 2008, with an overall cost of approximately $750,000.
The ovitrap program was suspended again following the most recent trap collections by GEMCO on 19/3/2014. It is expected that GEMCO will recommence the routine ovitrap surveillance program in the near future, given the proven receptivity of Groote Eylandt communities for exotic Aedes mosquito establishment.
To ensure Groote Eylandt remains free of the dengue vector, Medical Entomology (ME) of DoH visited Groote Eylandt between 19 and 21 March 2014 to carry out an exotic mosquito survey. Operations included larval mosquito surveys at various properties in Alyangula and Angurugu, setting of CO2 baited BG (BioGents) sentinel adult mosquito traps in the town of Alyangula and conducting a mosquito larval survey at the Angurugu sewage ponds. This report outlines the activities and results from this survey.
Alyangula mosquito larval survey
The yards of 25 properties were entered and surveyed for mosquito larvae on 19/03/14 and 20/03/14 (Fig. 1). Sixteen properties were positive for mosquito larvae. Of 66 receptacles that were found to be holding water on those properties, 35 (53%) were found to be colonised with mosquito larvae (Table 1).
Aedes notoscriptus larvae were sampled from 23 receptacles, Ae. katherinensis from ten and Ae. tremulus from one. These species lay desiccation resistant eggs and select breeding sites in a similar way to the exotic mosquitoes Ae. aegypti and Ae. albopictus (Asian tiger mosquito). The high number of receptacles holding water and being colonised by mosquitoes indicates that Alyangula remains vulnerable to widespread establishment of exotic Aedes species should they be introduced on cargo from international ports or from north Queensland.
DEPARTMENT OF HEALTH
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Alyangula adult mosquito trapping
CO2 baited BG sentinel traps were set in four locations in the residential area of Alyangula during the visit (Fig. 5) and were left to run for 24 hours. The most common species collected in all traps was Ae. notoscriptus. The overall number of mosquitoes captured in each trap was low, and no exotic species were collected in any of the traps.
Angurugu mosquito larval survey
Angurugu is an aboriginal community with approximately 170 properties. Most of these properties are residential, with most buildings at ground level or elevated on short posts (Fig. 4). Irrigation of common areas and residential yards is not very common and most properties are devoid of receptacles that would collect and hold water after rain.
The yards of nine properties were surveyed for mosquito larvae on 21/03/14. Four properties were positive for mosquito larvae. Of nine receptacles that were found to be holding water, five were colonised with mosquito larvae (Table 2). Aedes notoscriptus was sampled from two receptacles. No other Aedes species were sampled during the survey.
Angurugu sewage ponds – site visit
The Angurugu sewage ponds were surveyed on 20/03/14. Recommendations with respect to minimising mosquito breeding in the ponds and in any environmental releases from the ponds have been communicated to PowerWater.
Other activities
The routine CO2 trap sites at Alyangula have previously been fitted with a metal cabinet to hold a CO2 gas cylinder and steel posts to support the cabinet and mount the trap (Fig. 7). During this visit the old gas hoses were replaced at all sites.
Conclusions
Groote Eylandt remains vulnerable to an incursion of Ae. aegypti or Ae. albopictus. The most likely point of introduction will be the Alyangula wharf through international shipping. The close proximity of Alyangula’s residential areas to the wharf makes the town vulnerable to exotic mosquito introductions.
The temporary cessation of the routine adult mosquito trapping and ovitrap programs by GEMCO reduces the opportunity for early detection of exotic mosquitoes on Groote Eylandt. GEMCO should reinstate these important programs at the earliest opportunity.
DEPARTMENT OF HEALTH
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TABLE 1: Alyangula exotic mosquito survey 19 to 21 March 2014 - Summary of receptacle description and mosquito species collected.
LOCATION CONTAINER DESCRIPTION To
tal
No
. o
f p
ote
nti
al
co
nta
iner
s
To
tal
No
. o
f co
nta
iner
s in
spect
ed
To
tal
No
. o
f co
nta
iner
s w
ith
wate
r
To
tal
No
. o
f co
nta
iner
s b
reed
ing
% o
f co
nta
iners
wit
h w
ate
r b
reed
ing
Ae. (F
in)
no
tosc
rip
tus
Ae. (M
ac)
trem
ulu
s
Ae. (S
tg)
kath
eri
nen
sis
Cx. (
Cu
x) q
uin
qu
efa
scia
tus
Cx. (
Cu
x) s
pec
ies
Lu
. (M
et)
ha
lifa
xii
No
t id
en
tifi
ab
le
Tx.
(T
ox)
sp
ecio
sus
LS1 - Residence Smith St Pot plant base 1 1 1 1 100 1 0 1 0 0 0 0 0
LS2 - Residence Smith St Dog bowl 2 2 2 1 50 1 0 0 1 0 0 0 0
Pot plant base 1 1 1 0 0 0 0 0 0 0 0 0 0
LS3 - Residence Smith St Bucket (unspecified) 2 2 2 0 0 0 0 0 0 0 0 0 0