Journal of Mosquito Research, 2013, Vol.3, No.3, 14
-
20
ISSN 1927-646X
http://jmr.sophiapublisher.com
18
within indoor-resting and man-landing Ar. subalbatus
in tribal and non-tribal study areas.
Figure 3 Frequency of man-biting
Ar. subalbatus
in different
quadrants of day and night
2
Discussions
In the present study areas indoor resting
Ar.
subalbatus
was not the dominant mosquito species,
matching some other studies (Chandra, 1998; Chandra
et al., 2007; Paramanik and Chandra, 2010) but unlike
of some studies also (Das et al., 2003; Amala and
Anuradha, 2011).
The total number of
Ar. subalbatus
collected from
indoor-resting and man-landing conditions in tribal
areas was significantly lower than those of non-tribal
areas of the same district (p < 0.05). Suitable water
bodies available for mosquito breeding in many areas
of Bankura, often polluted and closely located with
human habitations (Paramanik and Chandra, 2012).
The non-tribal shelters, situated near open drains
blocked with garbage and polluted bodies around,
were more congested with furniture, clothings and
other household materials. On the other hand, the
tribal areas were situated within the forest areas.
Sanitary structures like sanitary latrines, stagnant
drains, cesspits, cesspools, cow dung gas plants etc.
were totally absent in this nature bound low-populated
tribal areas. The tribal shelters along with the
surroundings were clean enough due to their
socio-cultural background which does not make the
tribal area conducive for breeding of
Ar. subalbatus
.
Prevalence of higher number of this species in thickly
populated non-tribal areas i.e. towns, semi-towns
indicates maximum water pollution in comparison to
natural tribal areas. Ill developed sanitary structures
and unplanned urbanization in towns and semi-towns
of non-tribal areas favouring to build up
mosquitogenic sites especially for
Ar. subalbatus
and
Culex quinquefasciatus
due to heavy organic pollution.
Whereas in tribal area, the nature controls the
microenvironment and hence the surroundings are less
affected by the man-made pollution. As a result the
number of this pollution index mosquito,
Ar.
subalbatus
was very few along with lower prevalence
of
Cx. quinquefasciatus
,
filarial vector, causing lesser
filarial problem in these tribal areas of Bankura
district, West Bengal (Rudra and Chandra, 1998,
2000).
No significant seasonal variation was observed
in both indoor-resting and man-landing collections in
both the study areas (p > 0.05).
From 24 hour man-landing collections in non-tribal
areas, it was found that this species was mostly active
during the day. Among the other mosquitoes attacking
man,
Cx. quinquefasciatus
occupied the second place.
As a greater number of
Ar. subalbatus
were recovered
from outdoor baits, it can be presumed that this
species is exophagous in nature. Peak man-landing
hour was observed at dusk between 1700hrs and
1800
hrs in both study areas as also reported by Das et
al (1983). The other biting peak was noticed between
1800
hrs and 1900hrs after which the biting activity
decreased and increased again at dawn hours.
Though different parasitic infections like
Plasmodium
gallinaceum
(
Roy and Brown, 1970), Japanese
Encephalitis virus (Chen et al., 2000) and filarial
parasite
Brugia pahangi
(
Edson et al., 1960) have
been reported in
Ar. subalbatus
from different parts of
the world, no human parasitic infection was available
in this mosquito species in the current study areas.
3
Materials and Methods
The tribal study areas were situated within dense or
moderate forests, completely isolated from towns and
semi-towns of non-tribal areas of Bankura District,
West Bengal. According to data available from local
meteorological department, during the study period
(
from August 2009 to July 2010), average temperature
ranged from 17.87°C to 33.67°C, humidity from
39.65%
to 84.42% and rainfall from 0.00 mm to 235.3
mm in different months. One spot each in 8 tribal