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Northern Territory Department of Health Library Services Historical Collection
2\1.00302
VECTOR MOSQUITO SURVEY
NHULUNBUY AND YIRRKALA,MARCH 1983
1.0 INTRODUCTION
.9L µts, o I 4 .4..:23
L)P,'t'
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The North Australian Bauxite and Alumina Company (~ABALCO) town of Nhulunbuy and the nearby aboriginal community of Yirrkala are situated on the Gove Peninsula approximately 650 km east of Darwin.
Two officers from the Medical Entomology Section visited the two communities during 21-25 March 1983 to conduct an Aedes aegypti survey and to liaise with the Regional Heal th Surveyor
(Mr G. Butler) Nhulunbuy.
on vector mosquito control activities in
Prior to this survey the most recent search for Ae. aegypti, the recognised vector of dengue in Australia, had been conducted in April 1978. Ae. aegypti was not detected in either of the communities at that time.
The apparently widening distribution of Ae. aegypti in Queensland and the continuous air and sea traffic into Nhulunbuy from this state suggests there is a distinct possibility for the introduc- tion of this mosquito into Nhulunbuy and Yirrkala. The recent dengue epidemic in .Queensland highlights the need to ensure the Northern Territory remains free of this vector mosquito.
Vector mosquito qctivity in Nhulunbuy was surveyed by operating mosquito traps at both the town lagoon and nearby tidally influenced areas. Nhulunbuy South, Wallaby Beach and Yirrkala were also surveyed for vector mosquitoes.
An informal talk was held with the Regional Health Surveyor and the Senior Vector Control Officer (Mr D. Souter) to discuss vector control.
DL HIST 614.4323 DAV 1983
CENTRAL LIBRARY
TERRITORY HEALTH SERVICES POBOX40596
CASUARINA NT 0811
•
2.0 METHOD
2.1 Aedes aegypti Survey
To determine the presence of Ae. aegypti in the cornmuni ties by the following sampling techniques:
1. a survey of containers for mosquito larvae.
2. man-biting mosquito collections
3. adult mosquito trapping using carbon dioxide (CO2 ) baited traps.
Containers holding mos qui to breeding were sampled for mature specimens of each of the different looking mosquito larvae present. These specimens were preserved in 70% alcohol solution
and identified on return to the laboratory.
Man-biting catches were conducted during the early morning at two suburban premises in Nhulunbuy.
CO2 baited Traps were placed at a total of eight (8) sites around the Nhulunbuy and Yirrkala communities.
2.2 Vector Mosquito Survey
CO2 baited traps were used at two sites on the margin of the Nhulunbuy 'town lagoon' (one being the usual monitoring site) and close to the nearby tidal creeks (Buffalo Creek and Crocodile Creek). Another CO2 trap was placed SW of Nhulunbuy South adjacent to the conveyor, to sample for mosquitoes arising from the nearby mangrove area.
At Yirrkala two CO2 traps were used to sample the lagoon on the W edge of the community.
Larval samples were taken from a number of likely mos qui to breeding areas near Nhulunbuy and Wallaby Beach.
'
...
0067~
3
3.0 RESULTS
Results of the container breeding surveys are displayed in tables 1 and 2. A total of 173 premises were examined in the two communities; 409 containers were lound holding water and 42 of these held mosquito breeding. Six (6) different mosquito species were located breeding in containers.
No larvae of Ae. aegypti were found.
Results for the CO2 traps and man-biting catches are displayed in tables 3 and 4. No adults of Ae. aegypti were collected by these two methods.
Mosquitoes most commonly collected in the CO2 traps both in the communities and at nearby likely mos qui to breeding areas were Ae. vigilax, ex. annulirostris and ex. sitiens.
Results for the larval collections are presented in table 5.
4.0 DISCUSSION
4.1 Ae. aegypti Survey
Substantially greater than average rainfall occurred in Nhulunbuy during the period March 7th-13th, 1983 (218.7 mm for the period compared with the 72.7 mm average). Thus i t could be reasonably expected that at the time of the survey containers likely to support mosquito breeding when filled with water would have indeed held mos qui to larvae. Mos qui toes that utilise similar breeding sites as Ae. aegypti, notably Ae. notosciptus and Ae. tremulus were commonly taken from containers. Ae. noto- scriptus and Ae. tremulus were also' collected in the CO2 traps.
The presence of these two species indicates that if Ae. aegypti was present in the communities at the time of the survey, i t would most likely have been detected as larvae.
•
Not considering the industrial area, containers with water were most common in the Wallaby Beach and Nhulunbuy South residential areas ( an average of 5. 2 and 2. 9 containers with water per premise examined, respectively). Lowest numbers of containers with water per premise examined:· were located in Yirrkala ( average of 1. 5). Previous surveys in aboriginal communities have often revealed low numbers of containers with water per premises examined. For this survey only about one third of the premises examined in Yirrkala were occupied by aboriginals. The low incidence of containers holding water in Yirrkala is probably mainly due to the lower levels of gardening activity in the community compared to Nhulunbuy South and Wallaby Beach.
Highest incidence of mosquito breeding in containers was detected at Wallaby Beach ( average of 1. 5 containers holding mosquito breeding per premise examined). Lowest incidence of container breeding was detected in Nhulunbuy South, with only one container out of 52 with water, containing larvae.
Ae. notosciptus was by far the most common mos qui to located breeding in containers.
Containers most commonly located holding water were buckets and pot plant bases followed by ice-cream containers, miscellaneous kitchen items (dishes, bowls, plates) and tyres .
Comparison of the results of this container breeding survey with those of April 1978 shows, on average, an appreciably greater number of containers holding water per premise (1983 average of 2.3 containers with water per premise compared to 1978 average of
1. 2). The report for the 1978 survey mentions above average rainfall had occurred for the month of the survey. So i t is unlikely rainfall can account for the difference.
The extent of container breeding for the two surveys is compar- able. In 1978 about 11% of containers with water held mosquito breeding compared to 14% in 1983.
The collection of Tp. punctolateralis (to be confirmed), from a tree-hole breeding site is a new record for Nhulunbuy.
..
OOG7'3
5
4.2 Vector Mosquito Survey
4.2.1 Yirrkala
In general, moderate numbers of mosquitoes were collected in one nights operation of CO2 traps at Yirrkala. Only one trap catch approached high numbers. Half of this catch was Ae. vigilax, and such numbers indicate nuisance levels in the vicinity of the trap site and a potential for the trans- mission of the arboviruses this species is known to vector.
The lowest numbers of Ae. vigil ax were taken in the CO2 traps on the western side of the community, near the lagoon.
This indicates that the most likely source of this species would be the tidally influenced areas in the vicinity of Rocky Bay, SW of the community.
ex. guinguefasciatus was commonly collected in the two CO2 traps placed near houses. Most likely breeding sites in the community would be septic tanks and their overflows and containers holding polluted water. No septic systems were examined during the container survey. Septic systems need to be maintained such that there can be no mosquito access.
A mosquito awareness programme highlighting container breeding would be of value in reducing domestic mosquito breeding.
4.2.2 Nhulunbuy
Cx. annulirostris and Ae. vigil ax were the two species of mosquito most commonly collected, in CO2 traps, at sites on the margin of the town lagoon. The earlier CO2 trap catch at the town monitoring site ( 22/3/83) indicated moderate mosquito activity in that vicinity of the lagoon. This result contrasts strongly with the later CO2 trap catch ( 24/3/83) at the same site which indicated high levels of mosquito activity (mainly Cx.annulirostris and Ae.vigilax).
•
The initial catch at the town monitoring site would not be a good indication of mosquito activity in the vicinity, in general, because of the localised rainfall that occurred in that area during that night.
At the nearby tidal creeks (Buffalo Creek and Crocodile Creek), Ae. vigilax numbers were markedly greater than the numbers taken in CO2 traps at the town lagoon, while ex. annulirostris numbers were comparable.
These results agree with those of previous surveys in showing that the most important sources of Ae. vigil ax at Nhulunbuy are the two tidal creeks on its western and eastern boundaries. To have the greatest chance of being effective, control operations directed at Ae. vigilax require treatment of the breeding sites, either physically to ensure the area is free draining or using chemicals to kill the larvae, when breeding occurs. Both these alter- natives require the actual breeding sites to be identified.
A larval survey of Buffalo Creek was conducted on the 24th of March. Extensive areas at the extremities of the salt water influence were sampled for mosquito larvae. The upper
reaches of Buffalo Creek were also sampled. On the western margin of Buffalo Creek little free water remained after the heavy rains of earlier in the month. No larvae of Ae. vigilax were taken from a minor number of small pools on this western margin.
Vegetation patterns on this western margin indicate this area is unlikely to contain significant Ae. vigilax breeding sites.
On the eastern margin, near to the coast, an extensive shallow flooded area was sampled. Vegetation patterns in this area indicated a dominant fresh water influence. No mosquito larvae were located in this site. Further towards the actual creek line, a small number of Ae. vigilax larvae were taken from 3 small shallow pools in the mud flats inland from the mangroves lining the creek (see table 5).
..
7
Further inland along the eastern margin no breeding of Ae. vigil ax w·as detected and no likely important breeding sites for this species were located. The upper reaches of the creek line also failed to reveal any breeding of Ae. vigilax. However, likely breeding sites for Ae. vigilax were located in the upper reaches of the creek. This area needs to be examined for mosquito breeding a few days after high tides or heavy rainfall to determine its importance to Nhulunbuy as a source of Ae. vigilax. The larval survey of Crocodile Creek started on the eastern boundary but was unfortunately curtailed by steady rain.
If the important breeding sites cannot be identified the only control option remaining is to apply adul ticides in that zone between the breeding sites and the community. The recommended technique for such chemical control is the ultra low volume (U.L.V.) spraying of maldison, as per operational guidelines. To facilitate the 'fogging' of these source areas tracks need to be established and maintained relatively close to the areas of dense vegetation bounding the tidal areas of concern.
A track adjacent to Buffalo Creek is already in operation most of the year. Attention must be given to the condition of this track to ensure i t remains passable at the beginning of the Wet Season when Ae. vigilax breeding is still likely to occur.
There is a need for an effective track in the vicinity of Crocodile Creek. The likely alignment of this track was discussed with the Regional Health Surveyor and the Senior Vector Control Officer at the time of the visit.
When Ae. vigilax numbers at th~ town lagoon monitoring site exceed 50 in one nights catch then both the town lagoon and the Buffalo and Crocodile creeks areas need to be fogged as per the guidelines. Where numbers exceed 100 Ae. vigilax in one nights catch i t is recommended that two 'fogging'
operations be conducted in one week with one or two days between treatments.
High numbers of ex. annulirostris were taken in CO2 traps at the town lagoon and nearby tidally influenced areas. Suit- able freshwater breeding sites near Buffalo and Crocodile Creeks do not appear to last long into the dry season.
However the excess effluent from the Mt Saunders sewerage treatment works would most likely provide an important permanent breeding site for ex. annulirostris near Crocodile Creek. The piping of this excess effluent to the main town sewerage ponds would remove this breeding site.
The most important breeding site for this species at Nhulunbuy is the town lagoon, because of its proximity, size and permanence. Control options as mentioned for Ae. vigilax can also be considered. Identification of the important larval breeding areas is necessary if larval control is to be relied upon. Selective filling of some of the low lying areas bordering the residential area would remove important potential breeding sites. This option was discussed with the Regional Health Surveyor.
The drains which feed into the town lagoon need to be made free draining to ensure remnant pools are not formed in the dry season. Such remnant pools can become important breeding sites for Cx. annulirostris because there is often little predator ( fish) access and high levels of breeding can result from pollution due to urban run-off.
High numbers of Cx. annulirostris were collected in the CO2 trap at the rear of Nhulunbuy South. Apart from nearby natural breeding sites i t is likely that the effluent absorption line, from the oxygester which services the area, is also an important source of this species. The absorption area was not examined during this survey because no action had been taken on rectifying the mosquito breeding in this site since previous surveys had detected extensive breeding
0067~
9
of ex. annulirostris there (G. Butler pers. comm). This excess effluent still needs to be disposed of via properly constructed and maintained absorption lines or piped to the town sewerage ponds. If larvaciding is to be relied upon to
• ..
provide efficient control then access should be improved and the necessity for action be governed by a larval monitoring programme.
Very high numbers of Ae. vigilax and ex. sitiens were collected in the CO2 traps at Wallaby Beach. ex. sitiens is not recognised as an arbovirus vector. Likely breeding sites located during previous surveys are nearby old red mud ponds which are not free draining and the impounded water behind Baileys checkpoint.
At the time of the survey no water was impounded at Baileys checkpoint and only one ex. sitiens larva was taken from one of the pools in the old red mud pond area. (see Table 5).
A single ex. annulirostris larva was also taken from another pool in the old red mud pond area (see table 5). Areas of the mangrove margin nearby to Wallaby Beach that have been disturbed may trap both tidal waters after high tides, and rain, to produce a suitable breeding site for both Ae. vigilax and Cx. sitiens. All likely man-made mosquito breeding areas need to be made free draining to prevent mosquito breeding.
The larval survey of the Wallaby Beach sewerage ponds revealed substantial levels of breeding of ex. annulirostris amongst emergent weeds at the margins. The sewerage ponds need to be maintained weed free to promote wave activity at the margins which will prevent mosquito breeding.
CONCLUSIONS AND RECOMMENDATIONS
1. Ae. aegypti appears to be absent from the communities.
2. The relatively high incidence of containers with water in some residential areas of Nhulunbuy suggests such sites could constitute an important source of domestic nuisance mosquitoes and highlights the receptivity of the communities to the introduction of Ae. aegypti. A container clean-up campaign in the communities is likely to be of value.
3. High numbers of Ae. vigilax in Nhulunbuy are coming from the nearby tidally influenced Buffalo Creek and Crocodile Creek.
Possible control options are varied. Efficient control is only possible if the actual important breeding areas can be identified and treated with larvicide at the correct time.
Reliance upon adulticiding (ULV 'fogging') means appropriate access tracks must be established and maintained close to these tidal creeks.
4. High numbers of ex. annulirostris in Nhulunbuy are origin- ating from the town lagoon. Man-made breeding sites associated with sewerage excess effluents are of concern and should be rectified. Control based on larviciding means that essentially all of the shallow vegetated margins of the lagoon would need to be treated. Such control would be time consuming, expensive and almost impractical because of the difficult access. The recommended approach to mosquito control (including ex. annulirostris) in the town lagoon would be a combination of physical and chemical control.
Certain shallow vegetated lagoon margins nearest the residential area need to be filled, drains into the lagoon need to be made free draining and adulticiding would be used when the CO2 trap monitoring indicated the need. Filling of the lagoon margin, in areas, would also aid in the provision of a year-round 'fogging' access track. This 'fogging' track needs to be very close to the breeding areas to be able to treat the highest numbers of mosquitoes.
5. In general, vector mosquito numbers in Yirrkala, at the time of the visit, were moderate. Ae. vigilax is likely to be breeding distant from the community. Septic systems need to be rectified to prevent .mosquito entry.
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11
6. High numbers of Ae. vigilax and ex. sitiens in Wallaby Beach are most likely originating from the nearby old red mud ponds and mangrove areas. All likely mosquito breeding areas need to be made free draining. The Wallaby Beach
...
sewerage ponds are an important source of Cx. annulirostris.
If these sewerage ponds were maintained weed free, mosquito breeding in them could be prevented .
Officers Conducting Survey G. Davis
W. Kelton
OlC...
14.4A:C
~~OL-OG'--( {)RA!'A<:.Jri
~l io( tJ .
TABLE l
DISTRICT
NHULUNBUY
YIRRKALA
WALLABY BEACH INDUSTRIAL AREA
NHULUNBUY SOUTH
AIRPORT AREA
TOTALS
No. of No. of premises premises examined found
breeding mos uitoes
99 8
35 9
12 6
6 .1
18 1
3 1
173 26
* specimen sent to Dr.
Aedes aegypti SURVEY - NHULUNBUY & YIRRKALA - MARCH 1983 LOCATION OF SOURCE
No. of No. of Number of containers
containers containers Aedes Aedes Aedes Culex with water with larvae noto- tremulus sp. halifaxii
scriptus
216 10 8 1
51 l l 5 5 l*
62 .18 17 2
20 l 1
52 .1
8 1 1
409 42 31 7 1 2
E.N.Marks for identification - not Aedes aegypti
** experience suggests most likely ex. quinquefasciatus.
positive Culex quinque- fasciatus
2
6
5
13
*** Immature speciment - most likely Tp. punctolateralis. Identification to be confirmed by. Dr. E,N.Marks, Q.I.M.R.
for each species Culex Tripteroides sp. sp.
1 ***
l**
1 1
D 0
6>
...i ()Q
J'l
TABLE 2
Aedes ae9:y:eti SURVEY - NHULUNBUY & YIRRKALA - MARCH 1983 NATURE OF SOURCE
't-.
e- .2..
- Type of container No. of No.of Number of containers positive for each larval species
with water times times Aedes Aedes Aedes Culex Culex Culex Tripteroides container larvae noto- tremulus sp. * halifaxii quinque- sp. ** sp.
recorded present scriptus fasciatus ***
Buckets 61 5 4 l 2
• Pot plant bases 44 l l
..
Ice-cream containers 38 0Dish/bowl/plate 35 4 4
Tyres 34 7 4 3 l
Containers with 29 4 l 4
cuttings
Rainwater tanks 18 0
Drums (44gal,etc) 17 5 5 2 3
Flagon,carafe,jar. 12 l l
Watering can 12 0
Plastic barrel 8 l 1 l
Chair/seat 8 1 l
Baking dish/camp oven/
saucepan. 7 2 2
Garbage bin/lid 7 3 2 l
Margarine container 6 0
Wheelbarrow 5 l l
Cup/glass 5 0
Boat/canoe 5 1 l
Planter 5 0
Tin (paint/food) 4 2 l l 1
Plastic tarpaulin 4 1 1
Tray (plastic/metal) 4 0
Swimming pool 4 0
Teapot/kettle 3 0
Foam packing 3 1 1
Esky 3 0
Jug 2 0
Fridge crisper 2 0
Childs toy 2 0
Barbecue 2 0
Bath 2 0
Piping 2 0
Car body 1 0
Sink l 0
Metal cylinder l 0
Milk carton .l 0
Shell l 0
Cement mixer l 1 1 1
Fridge door 1 0
• Incinerator 1 0
A Fish pond (no fish) 1 0
Tree hole 1 .1 1 l l
Lunch box l 0
Wheel rim l 0
Paint tray l 0
Table top (warped) l 0
Linen basket l 0
Wooden box l 0
TOTALS 409 42 31 7 l 2 13 l 1
*Not Ae. aegypti. Identification to be made by Dr,E,N.Marks, Q,I.M.R.
** Experience suggest most likely ex. quinguefasciatus
*** Immature specimen - most likely Tp punctolateralis. Identification to be confirmed by Dr. E.N.Marks, Q.I.M.R.
TABLE 3. VECTOR MOSQUITO SURVEY - NHU1i,.UNBUY AND YIRRKALA - MARCH 1983 CO2 TRAP COLLECTIONS ( NUMBER OF FEMALE MOSQUITOES CAUGHT IN ONE TRAP IN ONE NIGHT)
LOCATION DATE SPECIES COLLECTED
. .
R
8~ ~ ~ ~ ::i::i (D ::i::i (D ::i::i (D ::i::i (D ::i::i (D ::i::i (D ::i::i (D ::i::i (D ::i::i (D ..0 n n X n X
R
n X ::r: 0 0. .
... .
... . . . . . . . . .
8b' Hi ::r' ::s p, p, (D Hi ::s t-o rt <! (/} X p, ..0 (/} (/} (/} (/} ~
p, p, r-'· 0 I-' I-' I-' i:: 0
~
ti r-'· t-o p, ::s i:: r-'· t-o t-o t-o en::s ti I-' . <! b' rt () ::s rt (D l.Q :::s :::s r-'· rt
. .
() p, I-' p, 0 (D ::r' (D 0 ~ r-'· -...J rt i:: :::s r-'· I-'
ti i:: r-'· l.Q (/} ti 0 ti (/} ~ I-' ~
·5
I-' ..0 (D w I-' lJ10 rt i:: () ::s (D (D () ti I-'
~ r-'· i:: :::s tv ~ -...J
Hi r-'· r-'· i:: p, ::s i:: ti (D i:: l.Q ti (D (/} -...J
rt :::s rt :::s (/l (/l r-'· i:: (/l p, 0 Hi
r-'· (D (D (/l r-'· t-o (/l (/l (/l p,
I-'· :::s I-' (/l rt rt rt (/l
(/l I-' i:: (D ti ()
I-'· p, (/l ti I-'· r-'·
(/l rt (/l p,
i:: rt
(/} i::
(/}
Industrial area, 23/3/83 3 J_ 70 7 3 67 15l
Nhulunbuy
House near school, 24/3/83 J_ 6 20 4 .15 8 3 57
Yirrkala.
House adjacent t~ craft 24/3/8.3 3 50 5 l9 ;23 100
centre, Yirrkala.
Amongst Melaleuca,Pandanu~ 24/3/8.3 l 3 J_2 .1 l 4 1 .1 24
rear of workshops, Yirrkala,
Adjacent to lagoon near 24/.3/83 l .1 3 4 .1 _l 2 3 l6
pump station,Yirrkala,
Nhulunbuy town monitoring 24/3/83 20 .128 584 732
site.
Rear of Nhulunbuy South, 24/3/83 .140 244 76 460
next to conveyor.
•
• .
...TABLE 3. VECTOR MOSQUITO SURVEY - NHULUNBUY AND YIRRKALA - MARCH 1983 CO2 TRAP COLLECTIONS ( NUMBER OF FEMALE MOSQUITOES CAUGHT IN ONE TRAP IN ONE NIGHT)
LOCATION
hulunbuy town onitoring site.
N m
0
t B
(Margin f town lagoon adjacent o intersection of eagle Crt. & Jasper Rd.) uffalo Creek adjq.cent to B
T V transmitter,Nhulunbuy R
N
1 1 2
N N 1 1
ear Baptist Church, hulunbuy.
2 Lacebark St. Nhulunbuy.
3 Sava St, Nhulunbuy Sth.
Raintree St. Nhulunbuy ear Crocodile Creek, hulunbuy
0 Wallaby Beach 9 Wallaby Beach
DATE
22/3/83
22/3/83
22/3/83
22/3/83 22/3/83 23/3/83 23/3/83
23/3/83 23/3/83
~ ~ ~ ~
. . . .
tr H) ::,' ::s
pi pi I-'· 0
::s H I-' <:
0 pi I-' pi
H c I-'· tQ
0 rt c
H) I-'· I-'·
rt !:1
I-'· (D
I-'· ::s
CJ) I-'·
CJ)
2 l
-
-16
8 -
~
24 28
SPECIES COLLECTED
~ ~ ~ ~ ~ ~ ~ ~
(D (D (D (D (D (D (D (D
. . . . . . .
pi pi (D H) ::s ro rt <:
I-' I-' I-' § 0
R
H I-'·tr rt 0 rt
J~
tQ
0 (D ::,' (D 0 ro I-'·
CJ) H 0 H CJ) C c I-'
0 ::s (D (D 0 H I-' ~
c pi ::s c H (D c
rt ::s CJ) CJ) I-'· c CJ)
(D CJ) I-'· ro CJ)
I-' CJ) rt
I-' c
pi CJ)
rt c
U)
2 l8
2 1 J_6 1 8 944
1 16 64
3 29
46 5
l 1728
1 8 .1184
4 540
(
.
• ii~ 0 0
R R R
0 ::r: t-3(D ~ X X 0 0
. . . . . . .
t-3CJ) X pi ~ CJ) CJ) CJ) CJ) ~
ro Ill ::s c I-'· ro ro i-o U1
!:1 ::s I-'· rt
. .
-...] rt c ::s I-'· }-'
CJ"\ ::,' I-' ~ (D w I-' U1
0 I-'· c ::s N CJ"\ -...]
tQ H (D CJ) -...]
pi 0 H)
CJ) CJ) pi
rt rt CJ)
(D H 0
H I-'· I-'·
CJ) pi
rt c
CJ)
50 3 76
4 456 64 1512
632 4 717
12 18 62
9 9 4 68
l 6
488 64 2289
32 1136 48 12433
160 732
<I
..
I
•
TABLE 4-.
VECTOR MOSQUITO SURVEY - NHULUNBUY AND YIRRKALA - MARCH 1983 MAN BITING COLLECTIONS NO. OF FEMALE MO~QUITOES CAUGHT IN THE TIME GIVEN
BY ONE COLLECTOR
LOCATION DATE TIME SPECIES COLLECTED
Ae. vigilax Cx. annulirostris 56 Banyan Street 23/3/1983 0635-
Nhulunbuy 0700 1
2 Raintree Close 23/3/1983 0635-
Nhulunbuy 0700 4 8
• ,J
...
•
I
.)
14.8V:2
TABLE S.
DATE 24/3/83
24/3/83
24/3/83
24/3/83
VECTOR MOSQUITO SURVEY - NHULUNBUY AND YIRRKALA - MARCH 1983
LOCATION
Old red mud ponds
Old red mud ponds
East side of Buffalo Creek
Sewerage Ponds Wallaby Beach
BREEDING SITES
Remnant low lying area adjacent to rehabilitated red mud ponds. No
vegetation or debris.
Water turbid (red), open, sunlit.
Remnant low lying area adjacent to rehabilitated red mud ponds. Among couch grass at shallow edges. Water turbid
(green), no predators.
SPECIES COLLECTED
Cx. sitiens
Open, sunlit. Cx. annulirostris Mud flats adjacent to Buffalo
Creek inland to mangroves.
Nil vegetation. Shallow,
tidal, sunlit. Ae. vigilax
Margin of sewerage ponds amongst emergent grass
and debris Cx. annulirostris
