Abstract:
This study was carried out in selected marshlands of Kelaniya in Sri Lanka to
determine the prevalence of various mosquito species larvae and their association
with biotic and abiotic parameters of the habitat. Larval sampling, recording of
physico chemical parameters and microfauna identification were done at monthly
interval from March 2015 to August 2015.
The study was carried out in eight marshlands with varying Biochemical Oxygen
Demand (BOD) levels and total number of 893 mosquito larvae were collected
(n=144). Culex gelidus, Cx. whitmorei, Cx. tritaeniorhynchus, Cx. quinquefasciatus,
Cx. fuscocephala and Anopheles sp. 1 were the species/taxa identified. Cx. gelidus,
Cx. whitmorei, Cx. quinquefasciatus were found in mashes with BOD level ranging
from 1.5-2 mg/L and Cx. fuscocephala with 1-1.5 mg/L. Anopheles sp. 1 was found
in significantly low level. pH levels in these habitats did not vary significantly and
lied between 6.5-7.0. When Cx. whitmorei and Cx. gelidus co-existed in one habitat,
it was found a significant negative correlation between the populations of two
species. Similar results were found when Cx. quinquefasciatus with Cx. gelidus
present together in same habitat. However, Cx. fuscocephala and Cx. gelidus when
present together in same habitat, it was shown a positive correlation.
In marshlands, 14 genera of microfauna were identified (n=144). Among them
Zoothamnium sp 1 was most common and found higher densities and followed by
Difflugia sp 1, Nauplius larva, Cyclops sp 1, and Daphnia sp 1. Pearson correlation
showed that there was a correlation between the density of mosquito larvae and
associated microfauna. Zoothamnium sp. 1 was given negative correlation with the
Cx. gelidus when they present in higher density. A significant positive correlation
was obtained between Daphnia sp. 1, Difflugia sp. 1, Nauplius larva and Keratella
sp. 1 with mosquito larvae. Hence, there is no relationship between microfauna and
mosquito populations. However, this may depend on the BOD of the habitat.
