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

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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

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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

Pot (gardening) 1 1 1 1 100 0 0 1 0 0 0 0 0

LS4 - Residence Connie Bush St Bucket (unspecified) 1 1 1 0 0 0 0 0 0 0 0 0 0

Cooking Pot 1 1 1 0 0 0 0 0 0 0 0 0 0

Polystyrene box 2 2 1 1 100 1 0 0 1 0 1 0 0

LS5 - Residence Brunker St Tyre (car) 1 1 1 1 100 0 1 0 0 0 0 0 0

Water feature 1 1 1 1 100 1 0 1 0 0 0 0 0

LS6 - Residence Brunker St Fish pond 1 1 1 1 100 1 0 1 0 0 0 0 0

LS7 - Residence Brunker St Pot plant base 1 1 1 0 0 0 0 0 0 0 0 0 0

LS8 - Residence Brunker St Self watering pot plant 2 2 2 0 0 0 0 0 0 0 0 0 0

LS9 - Residence Bougainvillea Drive Pool (child's) 1 1 1 0 0 0 0 0 0 0 0 0 0

LS10 - Residence Bougainvillea Drive Bucket (unspecified) 1 1 1 0 0 0 0 0 0 0 0 0 0

Drum lid 5 5 2 1 50 1 0 0 0 0 0 0 0

Pot plant base 4 2 1 0 0 0 0 0 0 0 0 0 0

LS11 - Residence Muninga St Nil containers 0 0 0 0 - 0 0 0 0 0 0 0 0

LS12 - Residence Bougainvillea Drive Clam shell 1 1 1 0 0 0 0 0 0 0 0 0 0

Drum lid 1 1 1 1 100 1 0 0 1 0 1 0 0

Plant cutting container 1 1 1 1 100 1 0 1 1 0 0 0 0

LS13 - Residence Bara St Nil containers 0 0 0 0 - 0 0 0 0 0 0 0 0

LS14 - Residence Muninga St Bucket (unspecified) 3 3 2 1 50 1 0 1 0 0 0 1 0

Clam shell 1 1 0 0 - 0 0 0 0 0 0 0 0

Fish pond 1 1 0 0 - 0 0 0 0 0 0 0 0

LS15 - Residence Bara St Bucket (unspecified) 2 2 2 1 50 1 0 1 0 0 0 0 0

Fountain (disused) 1 1 1 1 100 1 0 1 0 0 0 0 0

LS16 - Residence Bara St Nil containers 0 0 0 0 - 0 0 0 0 0 0 0 0

LS17 - Residence Bara St Plant cutting container 1 1 1 1 100 1 0 1 0 0 0 0 0

LS18 - Residence Arnhem Cres Nil containers 0 0 0 0 - 0 0 0 0 0 0 0 0

LS19 - Residence Smith St Bucket (unspecified) 1 1 0 0 - 0 0 0 0 0 0 0 0

Dog bowl 3 3 1 1 100 1 0 0 0 0 0 0 0

Pool (Swimming) 1 1 1 0 0 0 0 0 0 0 0 0 0

Rain gauge 1 1 1 0 0 0 0 0 0 0 0 0 0

Toy 2 2 2 1 50 1 0 0 0 0 0 0 0

Tyre (unspecified) 1 1 1 1 100 1 0 0 0 0 0 0 0

LS20 - Residence Arnhem Cres Nil containers 0 0 0 0 - 0 0 0 0 0 0 0 0

LS21 - Residence Ayawarra Cres Bath 1 1 0 0 - 0 0 0 0 0 0 0 0

Bucket (unspecified) 1 1 1 0 0 0 0 0 0 0 0 0 0

Esky 1 1 1 1 100 1 0 0 1 0 0 0 0

Tyre (unspecified) 5 5 5 3 60 1 0 0 0 0 1 0 0

Wok 1 1 1 1 100 1 0 0 1 0 0 0 0

LS22 - Residence Ngwunga St Pot plant base 3 3 3 3 100 1 0 0 0 0 0 0 0

Potty (child's) 1 1 1 0 0 0 0 0 0 0 0 0 0

LS23 - Residence Ngwunga St Bowl (unspecified material) 1 1 1 0 0 0 0 0 0 0 0 0 0

Tyre (car) 2 2 2 2 100 2 0 0 0 0 0 0 1

LS24 - Residence Ngwunga St Bucket (unspecified) 1 1 1 0 0 0 0 0 0 0 0 0 0

Tarpaulin 1 1 0 0 - 0 0 0 0 0 0 0 0

LS25 - Residence Cypress Rd Chook water 3 3 3 3 100 1 0 0 1 0 0 0 0

Dog bowl 1 1 1 0 0 0 0 0 0 0 0 0 0

Plant cutting container 1 1 1 0 0 0 0 0 0 0 0 0 0

Pot plant base 10 10 8 5 62.5 1 0 1 1 1 0 0 0

Wheel barrow 1 1 1 0 0 0 0 0 0 0 0 0 0

83 81 66 35 23 1 10 8 1 3 1 1

100 97.6 79.5 42.2 65.7 2.9 28.6 22.9 2.9 8.6 2.9 2.9

53.0

PREMISES AND POTENTIAL CONTAINER SUMMARY

NUMBER OF CONTAINERS POSITIVE FOR EACH

SPECIES

TOTALS

% OF TOTALS

% OF CONTAINERS WITH WATER BREEDING

DEPARTMENT OF HEALTH

Page 6 Department of Health is a Smoke Free Workplace

TABLE 2: Alyangula exotic mosquito survey 19 to 21 March 2014 - Summary of mosquito species collected in CO2 baited BG adult mosquito traps.

Ae. (F

in)

no

tosc

rip

tus

Ae. (M

ac)

specie

s

Ae. (S

tg)

ka

theri

nen

sis

An

. (C

el)

fa

rau

ti s

.l.

Cq

. (C

oq

) xa

nth

og

ast

er

Cx. (C

ux)

qu

inq

uefa

scia

tus

Cx. (O

cu

) b

ita

en

iorh

yn

ch

us

Trap location Tra

p t

yp

e

Date

set

Date

co

llecte

d

No

. o

f fe

male

s

No

. o

f m

ale

s

No

. o

f fe

male

s

No

. o

f m

ale

s

No

. o

f fe

male

s

No

. o

f m

ale

s

No

. o

f fe

male

s

No

. o

f m

ale

s

No

. o

f fe

male

s

No

. o

f m

ale

s

No

. o

f fe

male

s

No

. o

f m

ale

s

No

. o

f fe

male

s

No

. o

f m

ale

s

To

tal

No

. o

f f

em

ale

s

To

tal

No

. o

f m

ale

s

BG1 - Bougainvillea Drive BG Trap + CO2 19-Mar-14 20-Mar-2014 2 0 0 1 2 1 0 0 0 0 0 0 0 0 4 2

BG2 - Brunker St BG Trap + CO2 19-Mar-14 20-Mar-2014 3 0 0 0 0 0 0 0 0 0 0 0 0 0 3 0

BG3 - Ayawarra Cres BG Trap + CO2 20-Mar-14 21-Mar-2014 3 0 0 0 0 0 0 0 0 0 1 0 0 0 4 0

BG4 - Holland Rd BG Trap + CO2 20-Mar-14 21-Mar-2014 4 0 0 0 0 0 1 0 2 0 0 0 1 0 8 0

12 0 0 1 2 1 1 0 2 0 1 0 1 0 19 2

TO

TA

LS

TOTALS

DEPARTMENT OF HEALTH

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TABLE 3: Angurugu exotic mosquito survey 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

iners

To

tal

No

. o

f co

nta

iners

in

specte

d

To

tal

No

. o

f co

nta

iners

wit

h w

ate

r

To

tal

No

. o

f co

nta

iners

bre

ed

ing

% o

f co

nta

iners

wit

h w

ate

r b

reed

ing

Ae. (F

in)

no

tosc

rip

tus

Cx. (C

ui)

pu

llu

s

Cx. (C

ux)

qu

inq

uefa

scia

tus

Lu

. (M

et)

ha

lifa

xii

LS26 - Residence Box (plastic) 1 1 1 1 100 1 0 0 0

Pool (child's) 1 1 1 0 0 0 0 0 0

LS27 - Residence Boat 1 1 0 0 - 0 0 0 0

Bucket (unspecified) 2 2 0 0 - 0 0 0 0

Tyre (unspecified) 1 1 1 0 0 0 0 0 0

LS28 - Residence Bucket (unspecified) 1 1 1 1 100 0 0 0 1

LS29 - Angurugu store Bucket (unspecified) 1 1 1 0 0 0 0 0 0

Plastic wrap 1 1 1 0 0 0 0 0 0

Wheel barrow 1 1 0 0 - 0 0 0 0

LS30 - Residence Boat (dinghy) 1 1 0 0 - 0 0 0 0

Tyre (unspecified) 1 1 0 0 - 0 0 0 0

LS31 - Residence Boat (dinghy) 1 1 1 1 100 0 1 0 0

Tyre (car) 1 1 1 1 100 1 0 0 0

LS32 - Residence Plant cutting container 1 1 1 1 100 0 0 1 0

Pot (gardening) 3 3 0 0 - 0 0 0 0

Pot plant base 2 1 0 0 - 0 0 0 0

LS33 - Residence Nil containers 0 0 0 0 - 0 0 0 0

LS34 - Residence Nil containers 0 0 0 0 - 0 0 0 0

20 19 9 5 2 1 1 1

100 95.0 45.0 25.0 40.0 20.0 20.0 20.0

55.6

PREMISES AND POTENTIAL CONTAINER SUMMARY

NUMBER OF CONTAINERS

POSITIVE FOR EACH SPECIES

TOTALS

% OF TOTALS

% OF CONTAINERS WITH WATER BREEDING

DEPARTMENT OF HEALTH

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FIGURE 1: Alyangula exotic mosquito survey 19 to 21 March 2014 - CO2 baited BG adult mosquito trap sites, CO2 baited EVS adult mosquito trap sites and larval survey sites.

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FIGURE 2: Angurugu exotic mosquito survey 21 March 2014 - larval survey sites.

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Fig 3: Typical elevated house in Alyangula (lawn sprinkler in foreground)

Fig 4: Fairly typical ground level house in a Groote Eylandt community (low set without irrigated garden)

Fig 5: CO2 baited BG trap set at Alyangula residence for 24hr period to catch adult mosquitoes

Fig 6: Water holding garden ornament in Alyangula found to be positive for Ae. katherinensis and Ae. notoscriptus larvae.

Fig 7: Routine trap site at Alyangula golf club – cabinet to hold CO2 gas cylinder, post to hang trap assembly and hose to deliver CO2 to trap.