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Northern Territory Department of Health Library Services Historical Collection
2 l0:}461
AEDES AEGYPTI SURVEY OF GROOTE EYLANDT, JANUARY 1981
MEDICAL ENTOMOLOGY SECTION
NORTHERN TERRITORY DEPARTMENT OF HEALTH
INTRODUCTION
A survey of container breeding mosquitoes was conducted in three communities on Groote Eylandt over the period January 21-23, 1981 to check for the presence of the dengue vector Aedes aegypti.
Communities visited were the G.E.M.C.O. town, Aly"angula and the aboriginal communities at Umbakumba and Angurugu.
METHOD
Selected premises within the communities were searched for containers holding mosquito breeding. These containers were sampled for mature specimens of each of the different looking larvae present. Specimens were preserved in 80% alcohol and returned to the laboratory for identification.
Man-bi ting catches and carbon-dioxode (CO2 ) baited traps were used to supplement this container breeding survey in Alyangula.
RESULTS
Results of the container breeding survey are displayed in Tables 1 and 2. Within the three communities a total of 164 containers holding water were detected and sampled. Fifty-six (56) of these held mosquito breeding representing 9 species.
Ae. aegypti larvae were not -detected in any of the containers.
Results for the CO2 trap collections and man-biting catches conducted in Alyangula are displayed in Tables 3 and 4. No adults of Ae.aegypti were collected by either of these methods.
DL HIST 595.772 DAV 1981
2
DISCUSSION
1. Aedes aegypti Survey
The survey was conducted during .. _ the wet season when suitable breeding sites were available for container breeding mosquitoes such as Ae.aegypti. Other mosquitoes that utilise similar breeding sites as Ae.aegypti, notably Ae.katherinensis and Ae.tremulus were commonly detected in the container breeding survey. Hence if Ae. aegypti was breeding in any of the communities visited then i t is likely i t would have been detected. The results indicate Ae.aegypti is absent from the communities visited.
The most commonly collected container breeding species were Ae. katherinensis and ex. guinguefasciatus. Similar surveys conducted in the top end of the Northern Territory most commonly detect Ae.notoscriptus and Cx.guinguefasicatus. It would appear that on Groote Eylandt Ae.katherinensis, occupies the niche usually used by Ae.notoscriptus.
Ae.katherinensis is a member of the scutellaris group and in view of the proven ability of a number of members of this group to transmit dengue virus, the question arises as to the potential of Ae.katherinensis to also act as a vector.
As yet studies to determine the vector competence of Ae.katherinensis are incomplete.
The recent outbreaks of dengue in Queensland (earliest notfication in C. D. I. 82/4) highlight the need for such studies.
If Ae. katherinensis is demonstrated as a vector of dengue virus, in the laboratory, then ,the high prevalence of this species in the communities visited may mean a risk of dengue transmission if this virus was imported onto the island.
There are many other important features of a potential vector, apart from the ability to transmit virus, that must be assessed before i t can be assumed to be a significant potential vector. Such features include:
3
(1) the tendency of Ae.katherinensis to enter houses (2) whether i t is anthropophilic
(3) longevity of the mosquito
These features will need assessing if Ae. katherinensis is shown to be competent of transmitting dengue virus.
2. Other Species
2 .1 Aedes vigil ax 11The Salt Marsh Mos qui to 11
At the time of the survey plague numbers of the salt marsh mosquito (Ae. vigilax) were present in Alyangula and the prawn base at Bartalumba Bay. The collection of day-biting specimens in Angurugu suggests that plague numbers were also present in this area.
Three CO2 sites, all separated by at least 2km, collected similar numbers of Ae.vigilax (approximately 800/900). The sites were near the Alyangula Heal th Centre, near the turn-off to Bartalumba Bay and near Bartalumba Bay ( See figure 1). For this fairly even distribution of numbers to occur, the Ae.vigilax adults would most likely be spreading into the area from relatively distant breeding site/s.
Traditionally, Connexion Island (about 5km NW of Alyangula) has been thought to be the source of these plagues and yearly scrub burns have been conducted on this island in an effort to reduce the size of the plagues affecting Alyangula. If Connexion Island is the principal source of these plagues then the prevailing NW breezes of the early wet season would aid in the dispersal of the mosquito towards Alyangula.
A search of potential breeding sites on the island, following spring tides or heavy rainfall, is needed to determine if large suitable breeding sites for this species are present. Sites worth examining are evident
4
from aerial photographs. These distant breeding sites could also be on Groote Eylandt its elf and similar searches of potential breeding sites, as mentioned above, are necessary to identify the source of these plagues.
2. 2 Culex si tiens 11The Salt Water Culex Mosqui to11
The numbers of Cx.sitiens collected in the CO2 traps in Alyangula indicate the presence of an as yet undiscovered brackish water breeding site nearby.
2.3 Culex annulirostris 11Cornrnon Banded Mosquito11
The numbers of this species collected in the CO2 trap in the creek line near the shops in Alyangula indicates a nearby breeding site. This is most likely to be the lower reaches of the creek where i t runs along a boundary of the golf course. The creek receives run- off from the watering of the golf course greens. The mouth of the creek is usually blocked by dunes making these pools in the lower reaches semi-permanent in the dry season. Natural control of any mos qui to breeding in these waters by fish would be promoted if the pools were joined and they were kept free of debris that would provide harbourage for mosquito larvae.
CONCLUSIONS
(1) Ae.aegypti appears to be absent from Groote Eylandt.
( 2) Ae. katherinensis was the most commonly collected container breeding species.
There may be a risk of dengue virus transmission if this virus was brought to the island, because this species is closely related to known vectors of this disease.
5
( 3) Plagues of Ae. vigil ax influencing Alyangula may be coming from distant breeding sites. Possible breeding sites may be on Connnexion Island or Groote Eylandt.
G. Davis
W. Kelton
- / ) 0
Table 1
Aedes aegypti SURVEY GROOTE EYLANDT JANUARY 1981
LOCATION OF SOURCE
. ..
)Cation Number of Number of Number of Number of Species Incidence
1d Date Premises Premises Containers Containers·
~2.rched Examined with With Water with
Breeding Lar'.rae ~ :v :v ~ ~ ( ) n n 1--3
(1) (1) (1) (1) ::i >< >< >< 1-1
. . . . . . .
•.. X' !:J X' rt Pl Pl ::r' ~ to
.PJ 0 0 ~ ::i ::i Pl C C rt rt 0 (D ::i ::i !---' I-'· ~
::r' 0 ::r' ;3 C C l-'· ::i 0 (1) lJ) l-'· C l--' l--' Hi ~ rt
H 0 l--' I-'· I-'· Pl C 0
l-'· H C tU H >< (1) l--'
!:J l-'· Ul (D 0 I-'· I-ti p,
(1) i-o (/) (/) I-'· p, rt
~ rt rt (/) (1)
U) C t"-1 0 1-1
l-'· Ul l-'· I-'· p,
Ul (/) Pl !---'
rt I-'·
C (/)
(/)
~
lyangula 65 11 50 16 8 l ll 2 2 5 2
3/l/81
mbakurnba 28 7 46 15 6 I/ 1 2 4
ission 1/1/81
ngurugu 21 12 68 25 14 5 1 l l 13
ission 2(1/81
'OTALS ll4 30 164 56 28 6 l 8 l 4 2 20 6
..
Table 2
Aedes aegyPti SURVEY GROOTE EYLANDT JANUARY 1981
Premises Examined
ALYANGULA 23/1/1981
6 streets chosen at random, 65 premises searched.
34 containers with nil breeding.
Dry dump
UMBAKUMBA MISSION 21/1/1981
Housing Association yard
No.
1 1 1 1 1 1 1 1 1
2
1 1 1 2
1 2 1 1 1 1
NATURE OF SOURCE
Containers with Water Type
small aluminium cont.
with plant cuttings ice-cream container esky
foam packaging plastic bucket 5 gall. drum with plant cuttings ornamental pond (no fish) algae, grass plastic bucket
l '4 of 44 gall. drum under tree, organic matter
sea shells in garden, organic matter
metal bucket engine casting
~ of 44 gall. drum, organic matter truck tyres
galvanised roofing iron car tyres
car tyre wheelbarrow
cement mixer
shallow metal tank
Species of Larvae
Cx. quinquefasciatus Ae. katherinensis Cx. quinquefasciatus Ae. katherinensis Ae. notoscriptus Ae. katherinensis Ae. tremulus
Cx. quinquefasciatus Cx. halifaxii
Cx. annulirostris Cx. quinquefasciatus Cx. halifaxii
Cx. quinquefasciatus Cx. annulirostris Ae. katherinensis Ae. katherinensis Ae. katherinensis Ae. katherinensis Tr. punctolateralis
Ae. tremulus
/ /
Table 2 (cont)
Premises Examined
Dry dump
Nurses quarters
Community area (.23 houses)
roadside on way to Umbakumba
ANGURUGU MISSION 22/1/1981
Mechanics yard
No.
3 5 2 7 1 2 4
1 1
1 1 3 1 1 2 1 1 1 1
3 4
17 5 2 1 1
2
Containers with Water Ty;pe
Species of Larvae
Ae. tremulus Ae. katherinensis washing machines
vehicle tyres vehicle tyres various tins paint tin vehicle bodies
vehicle bodies (3) Ae. tremulus (2) Ae katherinensis (2) Tr. punctolateralis 4 gall. tin
44 gall. drum set in ground
esky, polluted water open sewage inspection hole, clean water rainwater tanks, screened
unused washing machine ice-cream container saucepans, polluted water
5 gall. tine vehicle hub cap
car tyre vehicle body
vehicle bodies vehicle bodies vehicle tyres vehicle tyres tins
vehicle hub cap 5 gall. drum
(2) (2)
(4) (3)
Ae. katherinensis Ae. tremulus
Cx. quinquefasicatus Cx. quinquefasicatus Cx. annulirostris
·Ae. katherinensis
Tr. punctolateralis Ae. katherinensis Tr. punctolateralis
Ae. katherinensis Cx. quinquefasciatus
Cx. quinquefasciatus Ae. katherinensis Ae. katherinensis Cx. quinquefasciatus
Table 2 (cont)
Premises Examined
Teachers houses (5)
Administration houses (2)
Aboriginal housing (10 houses)
on roadside, track from Angurugu to Yambugwa
TOTALS
No.
8 1 1 3 2 2 1 1 1 1 1 1
1
1 1 3 2 1 1 1
1
3
Containers with Water Type
over-full pot plants over-full pot plant bath, beneath tree ice-cream containers vehicle tyres
glass jars with cuttings
fish pond (no fish) algae, organic matter ice-cream container esky
paint tin
metal wash bucket water bowl in fowl yard
ice-cream container with cuttings
vehicle tyre vehicle tyre
saucepans, polluted water
ice-cream containers metal bucket
5 gall. drum plastic bucket
large truck tyre in open forest
Species of Larvae
Ae. katherinensis Ae. notoscriptus Ae. katherinensis
Cx. quinquefasciatus Cx. annulirostris Ae. katherinensis Ae. notoscriptus Ae. katherinensis Ae. notoscriptus Ae. katherinensis Cx. quinquefasicatus
Cx. katherinensis
Cx. quinquefasciatus Cx. quinquefasicatus
Cx. quinquefasciatus Ae. notoscriptus Ae. notoscriptus Ae. katherinensis
Ae katherinensis An. annulipes
Ae kochi
(x): number of times species recorded 114
30 164 56 9
Premises examined
Premises with mosquito breeding Containers holding water
Containers with mosquito breeding Species represented
/ I
Table 3 Aedes aegypti SURVEY GROOTE EYLANDT, JANUARY 1981 Number of female mosquitoes caught in one trap in one night
SPECIES
~ ~
. .
~.
~.
~ (D.
~ (D.
~.
~is'
\ @ (D
i
A" r-'8
!:1 t-(j ~r-' 0 ~· 0
]
~ &
()~
rt!
g
(1) 0~ PJ Ul
LOCATION DATE rt (D rt ()
f-'· ~
g
0 l"i (Dg
0
1
f-'·g
ft
en f-'· f-'· I-'· Ul t-(jg
en
Alyangula, in scrub adjacent
to health centre 20. i.1981 1 1 1 1
A:Lyangula, in scrub on creek
line near shops 20. i.1981 1 13 25 1
In scrub adjacent to Rowell -
Hwy lOOm before turn-off to 20.i.1981 4 10
Bartalumba Bay (7)
--
·~ear LHS of road Bartalumba Bay -~km before bay track on 20 .i.1981 3 2 3 1 (5) 0
\lyangula, rear year No.· 10 21.i.1981 10
rasman Street
\lyangula, rear year No. 10
rasman Street 22 .i.1981 3
· ~ ·
.
tQ
~-
I-'·
r-' ~
900
540
925
800
400
226
CO2 TRAP COLLECTIONS
(x) : number of males COLLECTED
IB'
~ .? ? ?
. .
Ul
~.
tJ' ::J"'
8
t-(j
.
§ I-'· r-' ~()
8
r-'r-' rt f-'·
g.
°'
0g .
t-ti rtf-'·
0
f-'·
Ul f-'·
Ul
1 1
1 1
~
1
2 10
2
1 1
Ji . .
( J X~ l
~ g:
Ul 1-'·8
Ul· &
.Ul ~ f-'·6 13
1 48
24 35 (1)
10
3
2
----- -
.
.
~Jl
(D~ Ul () I-'·
OJ
ff
0 (2)
-2
L
~
...
~
2
l
l (
'
l . - -
TABLE 4 Aedes qegypti SURVEY GROOTE EYLANDT, JANUARY 1981 MAN-BITING COLLECTIONS
Number of female mosquitoes collected by 2 collectors, in the time given
LOCATION DATE TIME SPECIES COLLECED
~ ~ n n
(1) (1) :>< :><
. . . .
X' < PJ Ul
0 I-'· ~ I-'·
0 LQ ~ rt
:::J' I-'· C I-'·
I-'· f-' f-' (1)
PJ I-'· ~
:>< H Ul
0 Ul
rt H I-'·
Ul
Near Baralumba bay
-
track on 19/1/1981 1935-1938 127 1 2LHS of road ~km-before bay Alyangula, in scrub on creek
line near shops 19/1/1981 2000-2005 1 _142 1 2
Alyangula, in scrub at corner
of Poinciana and Smith Streets 19/1/1981 2010-2015 148 2 Alyangula, in scrub at corner
of Poinciana and Smith Streets 22/1/1981 1935-1945 106 10 2
Angurugu, rear yard of house in One Collector
administration area 22/1/1981 Approx 1040
Hours 4
• '<JVI -· ••
~ '
.
-
N _
1
km
f j I t
0 l•O 1·5
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l.£6~1'JO ____., Dr~
f /
J J /Grrusl(l;Y\J
19 · f"reshw~
swCLO'\f'- ~ Op€,n 6,rcctt,pt f'r:rrest
~ on r ~ ~3h ~Un<
~ o~~~pr
"
, Salt ·inftvene:J C01- h--C\f ~,te C\.,\-f.R
p=~s~r~\~t<
MuJ -t\ctl:-
rv1 am5 ,o~'-e,S
Dense ~rest:
- ~\b\.Q, /J,e_.vi~;lel:
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