Vector mosquito and quarantine survey, north coast of the Northern Territory, 2-12 November 1985

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dOS.lk, HISTORICAL COLLECTION

VECTOR MOSQUITO AND QUARANTINE SURVEY NORTH COAST OF THE NORTHERN TERRITORY

DL HIST

595.772

SMI

1985

2-12 NOVEMBER 1985

MEDICAL ENTOMOLOGY BRANCH

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Vector mosquito and Quarantine survey North

Coast

of the Northern Territory

2 - 12 November 1985

Medical

Entomology

Branch

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46282

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CENTRAL LIBRARY

- 6 MAR 1998

Northern Territory

Department

of

Heal

th

TERRITORYHEALTHSERVICES

1. 0 INTRODUCTION

As in previous years, the Commonwealth Quarantine Service organised and conducted a 30 day quarantine survey of the North Coast of the Northern Territory between Gove and Darwin during October-November 1985. The survey was divided into 3 x 10 day patrols and i t was intended that the participants visit as many settlements as possible, liase with the various communities on quarantine matters and search for possible unauthorised landings on remote islands or beaches. I t·was also planned to carry out a survey of vector mosquitoes during one of the patrols and an officer of the Medical Entomology Branch of the Northern Territory Health Departmen~.joined the survey for the second 10- day patrol between Maningrida and Croker Island, the itinerary of which is given in Appendix I, along with a map showing each location visited <Map 1>.

The mosquito survey was intended to examine a proportion of water-holding containers at various settlements to check on the absence of Aedes aeqypti and to gain more information on adult mosquito abundance along the North Coast.

Specific mosquito surveys have been conducted by the Medical Entomology Branch at Croker Island <February 1981), South Goulbourn Island and Maningrida <February/March 1981) and previous coastal surveys from January-March 1980, May/June 1981 and August 1983. Reports on these surveys are available from the Medical Entomology Branch.

2. 0 METHODS

2. 1

General

container

search

An Aedes container survey was conducted where possible to determine whether Ae. aegypti was present and to detect other species breeding. The survey was carried out by searching and

~xamining any water-containing vessels for mosquito larvae. Where found, larvae were collected into labelled vials, transferred to 70% alcohol and returned to the laboratory for identification.

2. 2 Adult mosquito survey

The presence and relative abundance of adult mosquitoes was determined by the use of CO2-baited traps placed near settlements and likely mosquito breeding or harbourage areas. These traps were placed at sundown and collected after sunrise next morning, when the mosquitoes were killed and stored for later identification in the laboratory. Locations of CO2-baited traps

placed· near Warrawi,, .·,South Goulbourn Is. and Minjilang, Is. are shown on accompanying Maps 2 and 3.

2. 3

Occasional

collection or

adult mosquitoes

Croker

A.s the o_pportuni ty arose, adult mos qui toes were collected as they

· were att"racted to humans. These specimens were killed, labelled,

mounted and identifications were later confirmed under the microscope.

3. 0 RESULTS

Due to the timing of the patrol and the lack of rainfall in the areas visited, the numbers of breeding places and adult mosquitoes were low as is to be expected at this time of the year. The first significant seasonal rainfall of approx. 20 mm occurred at Warrawi on 5 November 1985 while Minjilang recorded the first fall on 6 Nove~ber 1985 (37 mm>.

3. 1 Container surveys

Surveys were conducted at 4 settlements, two of which were large communities while one was an inhabited outstation and the fourth was an outstation uninhabited at that time, but situated close to a permanent well. The res~lts ··or these surveys are presented in Tables I-IV. Due to the very dry conditions prevailing, larvae were found in only 3 containers, a cooking pot at Warrawi which produced Culex quinquefasciatus and two tyres in the school-yard at Minjilang which contained Ae. notoscriptus / Ae. tremulus and Ae. notoscri ptus respectively.

At Warrawi, 39 premises were examined <Table II>, producing 25 water-filled containers only one of which contained larvae.

However, mosquitoes which could exploit these containers were breeding at 3 other sites (drains and broken water main) within the community and i t was probable that the lack of rain. had prevented larval establishment in at least some of the more polluted containers. Similarly, at Hinjilang 31 premises were examined <Table I>, resulting in 83 water-filled containers of which only two tyres produced larvae. Although this community had some other breeding places for these mosquitoes, none had been exploited.

3. 2 Adult trapping

A total of 16 CO2-baited traps were set and results are tabulated in Table V. Seventeen species were represented in the catches but only Ae. vigilax, the salt-marsh mosquito and Cx. quinque- fasciatus Cat one site> were in high enough numbers to be termed

11 nuisance level". Two species of Anopheli ne mos qui toes, An.

farauti and An. hilli were collected, but in very low numbers.

The trap with greatest diversity collected nine species and was set at the edge of a rain forest and fresh water swamp area.

3. 3 Other adult collections

In addition to the adult collections from the CO2-baited traps, Ae. vigilax was captured during the day in dense scrub on McLure Island and at Maud's Creek near Minjilang while Cx. sitiens was caught at night on board the yacht anchored at least 0. 5 km

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offshore in the .Oxi~~ Gr-0up of islands and in Mission Bay, the Minjilang community.

4.0

DISCUSSION

off

The generally low numbers of adult mosquitoes <except for Ae.

vigilax> and of container breeding sites was due to the prevailing weather conditions. Although Cx. quinquefasciatus was breeding at Warrawi in open drain~ and other water pools, i t had colonised only one container. This was possibly due to its preference for polluted water since many of those containers which held water at the time of the survey were relatively unpolluted. Adult populations of container-breeding mosquitoes

< Ae. notoscriptus, Ae. tremulus, Cx. guinquefasciatus> were low, as expected from the small number of larvae found and the CO2- baited (Table V> traps failed to detect the presence of Ae.

notoscriptus in the communities surveyed.

The collection from Inyjalataparri Outstation contained a significant number of biting midges although adult mosquitoes numbers were relatively low, possibly due to the presence of smudge fires set in the late afternoon to deter both Ae. vigilax and biting midges.

From these surveys, i t is not possible to conclude that Ae.

aegypti was absent from the communities, although the fact that the dengue fever vector had been absent at previous surveys suggests that this sp~cies was unlikely to have been present in the settlements at that time. However, the detection of species which have very similar breeding sites to Ae. aegypti, such as Ae. katherinensis, Ae. notoscriptus and Ae. tremulus, on earlier surveys <e.g. South Goulbourn Island in February 1981 > indicates that these communities at least, may be receptive to the introduction of ~- aegypti and stresses the need to rectify container breeding in the communities along the North Coast.

Despite the unsuitable time of the year, adult catches did produce additions to the recorded mosquito fauna on South Goulbourn Island and at Minjilang. On the former island for instance, Ae. elchoensi s and Ae. reesi were collected for the first time, bringing the number of known mosquito species on that island to 21 while at Minjilang, Ae. elchoensis, Uranotaenia albosternopleura, Ur. hirsutifemora and Ur. moresbyensis were new additions to the 27 species now known from Croker Island. The three species collected from North Goulbourn Island <An. hilli, Ae. vigilax and Cx. sitiens> and the collections from both McLure Island and the Oxley Group were the first recorded for these localities. No further additions to the 31 known species of mosquitoes at Maningrida were made during this survey.

Anophelines were collected at only two sites, An. hilli at North Goulbourn and one specimen of An. farauti at a fresh water swamp near Minjilang. This latter species is probably the principal malaria vector in the Northern Territory and is widespread along the mainland north coast.

The very high numbers of Ae. vigilax recorded from Maningrida and South Goulbourn Island are probably a result of recent high tides (15-17 October> flooding coastal breeding areas. This species is

3

a vector of Ross RiV~r Virus and indicates the potential for the transmission of this virus s e t t 1 e me n t s .

relatively in these

high two

Discussi-0ns with community health workers on the incidence of arthropod-borne disease in the area indicated that the prevalence was very low even though the life style of members in the

~ommunities enhances contact with mosquitoes, especially since the majority of houses had inadequate insect screening on windows and doors. However, this contact during periods of high mosquito activity is likely to make the communities receptive to arbovirus diseases and malaria i f the parasites are introduced or present in the area.

5.0 Acknowledgements

I am grateful to Hr. and Hrs. J. Saltmarsh of the 'Shiralee-S', Quarantine officers Hr. P. Blackadder and Mr. S. Wakelin and to the authorities 1n the various communities visited for their advice and assistance in these surveys.

E. S.C. Smith

Officer conducting survey

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TABLE I. WATER CONTAINER

SUll!JE'C-

"_I_N_f~LAN6, CROKER ISLAND 11 Nove1ber 1985

I

Negative for larvae Positive for larvae Species detected

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TOTAL ABORIGINAL DWELLINGS

I

26 ho1Jses, 72 containers mained

I

I I

TOTAL EUROPEAN DWELLINGS

I

2 houm, 6 containers exaained

I

I I

TOTAL OTHER BUILDINGS

I 3

buildings,J containers exaained

I 1

building,

2

containers exaained

CONTAINER TYPE

21)0 1

drlJI

20 l dru1

20 1

b1Jcket

5 1

dr1J1

Ice crea1 container Cooking utensil Fridge body/esky Wash tro11ghs/basins Washing tachine Tyre

Boat/canoe/dingy

Swi11ing pool

Car body Bott

le

She 11

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Aboriginal E1Jropun P1Jb

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6 6 2

t6

5

8

4

2

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..

Aboriginal E1Jropean P11b

lie

2

Ae. notoscriptus Ae. tre1ul11s

Copper with cuttings

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--- ! POOLING OF WATER

Dripping tap/hydrant Broken water/sewer aain

5

2

TABLE II.

WATER

CONTAINER ~URYEY -

WARRAWI,

SOUTH 60ULBOURN ISLAND

4 Nove1ber

1985

I I

TOTAL ABORIGINAL DWELLINGS

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TOTAL EUROPEAN DWELLINGS

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TOTAL OTHER BUILDINGS

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CONTAINER TYPE

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200 l dru1

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I

20 l dru1 ,

I ^..

20 l bucket

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5

1

dru1

I

I

Ice

crea1

container

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Cooking utensil

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I

Fridge body/esky

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Wash tro1Jghs/basins

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Washing 1achine

I

I

Toilet pan

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Negative for larvae Positive far larvae Species detected

:

- - - - I

26 houses, 25 containers exaained

I 1

ham,

1

container mined

I

5 houses, 2 containers

exa1ined I

7 buildings,O containers

exa1ined

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Aboriginal EtJropean

Public I

Aboriginal European

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PtJb

1

ic

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3 ·1 . I

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3 I I

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3 I

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Cx. ~uinmfmiat1Js

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--- i

POOLIN6 OF WATER

Dripping tap/hydrant

3

Broken water/sewer

1ain

Cx. annulirostris

Cx. ·~1Jin·~1Jefmiatus

I

Open drain

13 5

Cx. annulirostris

I

Cx. quinmfasciatus

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Unscreened water tanks

b

Unsaapled

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Well Unsaapled

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Sewerage

ponds Cx. annulirostris

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TABLE III. WATER CONTAINER SURVEY - INYJALATAPARRI OUTSTATION, via WARRAWI, SOUTH 60ULB0URN ISLAND

05

Noveaber

1985

I I

TOTAL ABORIGINAL DWELLINGS

I

CONTAINER TYPE 200 l dru1

20 l

drua

20

l bucket

5

l drua

Ice creaa container Cooking utensil Fridge body/esky Wash troughs/basins Washing 1achine Tyre

Boat/canoe/dingy

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Negative for larvae Positive for larvae Species detected

--- i

2

houm,

14

containers exained

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Aboriginal

3

8

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Tray

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TABLE IV. WATER CONTAINER SURVEY - SANO"P01NT, SW NORTH 60ULBOURN ISLAND 03 November 1985

Negative for larvae Positive for larvae

Species

deteded

1 l

--- :

TOTAL ABORIGINAL DWELLINGS I I I I I I

CONTAINER

TYPE

200 1 dru1

20 1 dr·!JI

20

1

b1Jdet

5 1 dru1

Ice

crea1

container Cooking 1Jtensi

¹

Fridge body/esky Wash troughs

/basins

Washing aachine Tyre

Boat/canoe/dingy

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3 caps

e

x

a1ined, no containers

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Aboriginal

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Tray

^{I I}

--- I

Well

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--- I --- I

Yes

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Cx. annulirostris

L2 ^I

!

Cx. sitiens L4

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t

L2 and L4 refer to 1osq1Jito larval stages two and fo1Jr respectively

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TABLI

5A.

Location-a, ot 15 CO2-baited traps on North Coast Quarantine survey - November 1985

Maningrida

1 Police Station.

2 Creekline to right or barge landing.

North Goulbourn I1land

1 Sand Point, SW corner. 50m from camp, 50m from well.

2 Halfway along South Coast at abandoned camp;

sea, 50 m from well.

South Goulbourn Island

SOm from

1 1km SE or Warrawi nr . . lowlying seepage area, now dry.

2 3. 5km NW or Warrawi at camp on edge or brackish lagoon, now dry.

3 1 km NW or Warrawi at edge or Melaleuca swamp.

4 House i~S 5, Warr a wi community. Tree in rear yard.

5 Barge landing, 5km WSW or Warrawi.

Pandanus / Helaleuca swamp.

50m inland at dry

6 Inyjalataparri Outstation, 5kmC7km by road> from Warrawi.

7 Warrawi community, rear of Council Offices <Building# 44).

8 100m Nor house# 51, along heavily timbered creekline and 50m from mangroves.

Croker Island

1 0. 5km Nor Minjilang at small dam on W side or road to pump.

2 House or Essential Services Manager, Hi nj i 1 ang community.

3 1 km Sor Hinjilang on old airstrip near Jap Creek.

4 Spring pump, Maud's Creek 3km N of Minjilang.

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TABLE V. Nuabers of fe1ale 1osquitoes collected per CO2-baited trap per trap night in the North Coast Quarantine survey - Nove1ber

!

SPECIES

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---4

I

An. farauti

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An. hilli

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I

Ae. elchoensis

I I

Ae. kocki

^I

I

Ae. reesi

I

I

Ae. tre1ulus

I I

Ae. vigilax

I I Cx.

annulirostris

I I Cx.

q1Jin1uefasciatus

I I Cx.

sitiens

I I

Cx.

sp.

32 I

I Cq.

xanthogaster

^I I

Ho. sp. 157

I I Na.

uniforais

I I

Ur. albosternop

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!Jr. ~irsutifeaora

I I

Ur. aoresbyensis

I I

---4

I

TOTALS I

I

---4

Nth

Naningrida 6oulbourn Is

2 2

3

South 6oulbourn Island

2 3

4

5 6

5 202 1192 22 1988 27 120 307 8 16 63 18 24

2

4

. ,

i.

4 18

9 6

6 10

2

7

48

Croker Island

8 2 . 3 . 4

2

18 6 2

10 15

1 .

2

24 2 57

14

3

TOTAL

3

3 5

6

3997 167

67 5 15 5

4 4

10 10

3 3

15 15

4 4

I

220 1228 23 1992 34 124 331 18 29 75 49 30 24 2 83 49 I 4311

I

Note:

Identification of Ur. albosternopleura

awaiting confiraation

MAP 1.

tOP END COASTLINE OF THE NORTHERN TERRITORY

Locations visit~d,·,' -~re circled

Simple Conic Pr

Truar

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MAP 2.

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Locations of CO2 traps set near Warrawi, South Goulbourn Island, November 1985

---

^----<

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^...

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---~--- -----. --. --- .

.

· --- ---- ---

---

^.

.

,---

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^,

- - - - ---

----

^{--....__ .. _}

--- --...

- --- --- · ---.

----

· - ---

---- --

^---...

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---

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- - ---- - - ---- -- -- -~ -- -- -

^{-. __ ..}

-

^.... .._...__ ..

--- . ·--

MAP 3. Locations of CO2 traps set near Minjilang, Croker Island, November 1985

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APPENDIX I

ITINERARY

Saturday 02 November 1985

0945-1230 Coastwatch surveillance flight Darwin-Maningrida.

Immediate transfer to MV Shiralee S.

1245-1330 1400-1630

Motored to Entrance Island to allow harbour exit at low tide

Surveyed circumference of Entrance Island on foot Sunday 03 November 1985

0545-1300 Motored Entrance Island-North Goulbourn Island 1330-1730 Circumnavigated North Goulbourn Island by dingy,

landing at several places

1730-1930 Set CO2 traps at two ·sites on island November 1985

Collected CO2 traps··

Monday 04 0600-0800 0930-1300 1300-1730 1745-1915 2000-2130

Motored North Goulbourn- South Goulbourn Island Container survey, Warrawi community

Set CO2 trap• at four sites near Warrawi Sorted larval, adult samples

Tuesday 05 November 1985

0600-0730 Collected CO2 traps

0830-1200 Discussions with Warrawi community Inyjalataparri Outstation

1430-1700 Barge landing, further discussions and surveys

leaders, to container 1730-1915

2000-2100

Set CO2 traps at further four sites on South Goulbourn Island

Sorted larval, adult samples Wednesday 06 November 1985

0600-0730 Collect CO2 traps

0815-1430 Motor South Goulbourn-Grant Island; anchor W coast 1430-1830 Survey E half of Grant Island by foot

Thursday 07 November 1985

0630-1100 Circumnavigate Grant Island by dingy

1230-1430 Motor Grant-McLure Islad; anchor SW coast

1500-1900 Circumnavigate McLure Island by dingy; landed Wend Friday 08 November 1985

0930-1415 Survey McLure Island by foot · Saturday 09 November 1985

0630-0830 Motor McLure-New Year Island 0915-1115 Survey New Year Island by foot 1545-1800 Motor New Year-Oxley Group Sunday 10 November 1985

0800-1115 Survey Oxley Group by dingy along W coast

1445-1730 Survey E coast by dingy, landing at several places

Monday 11 November 19~5

0700-0845 Motor Oxley Group-Mission Bay, Croker Island 0930-1230 Container survey, Minjilang community

1500-1730 Examine sewerage ponds, rubbish dump, possible larval breeding areas, discussions with community leaders etc.

Tuesday 12 November 1985

0830-0945 Discussions with Essential Services Manager, School children etc.

1000-1410 Coastwatch surveillance flight Minjilang-Haningrida- Hilingimbi-New Year Island-Croker Island-Darwin

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APPEND IX II

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.. . ~'

List of 1osquito species recorded fro1 three localities along the North Coast of the Northern Territory

l Medical Ento1ology Branch - Northern Territory Oepart1ent of Health

l

^{I I I}

SPECIES

I

NANINGRIDA

I

WARRAWI,S.60ULBOURN IS.

I

~INJILANG, CROKER ISLAND

i

l

^{I I} _I ^{NAR NAR}

1980 1981 1982 1983 1985 JUNE AUG NOV

^{I I I}

1980 1981 1983 1985 JAN FEB AUG NOV

^{I I} I 1980 ^NAR

FEB 1981 1982 1983 1985 JUNE AUG NOV

^{I I} I

l ---~

--- I --- I --- I

I I l

An. bancroftii

I X X X I I X X

An. farauti

I X X X I X I X X X

- 1 An. hi An.

1eraukensis ¹¹

i

^I I X ^X X ^{X X} X ^I I ^X X ^{X I} I ^X X

An. novaguinensis

I X I

] An. p owe

11

i

I X I

Ae. alter·nans

I X X I X

Ae. daliensis

I X

] Ae. elchoensis

X I X

Ae. f1Jnereus

X X X l X

Ae. katherinensis

X I

Ae. kocki

X X X I X

] Ae. nor1anensis

^{u _:.,} I

Ae. notoscriptus

^X X X X ^\I " I X X

Ae. pijrpureus

X X I

] Ae. reesi

X I

Ae. stoneoru1

I

Ae. tre1ul1Js

X X X X I X X X X

Ae. vigilax

^X X X X X X X ^u -~ I X X X

J Cx. annulirostris

^{u ....} X ^{u h} X X X X X X X -~

Cx. bitaeniorhynchus

^X X X

Cx. halifaxii

X X i.

J

Cx. hilli

X

Cx. Nor1anton sp.

X

Cx. pu

11

us

X X X X

J Cx. quinquefasciatus

X X X X ^{u ;.. \J} h X X X

Cx. sitiens

^X X X X X X X X X X

Cx. squaaosus

X X

Cx. sp. 32

A X X " X

J Cx. sp. Ad. catasticta 167

^{X h} X ^X

Cq. xanthogaster

X X X X X X X A

J Na. uni for·

¹

is

^X X X X

Tr-. aagnesianus

X

Tr. punctolateralis

^V h X

J Ho. sp. Ur. albescens 157

^{X X I} I ^{X X X}

Ur. albosternopleura

f I

Ur. hirsutife1ora

I

J Ur. lateralis

X I

Ur. 1oresbyensis

I X

Ur. novaguinensis

^X I

J Ur. sp. ---~

^I --- I --- ! ^{I X} ---^{X ·X} i

J

^f

identification awaiting confir1ation