Abstract:
Rice fields in Sri Lanka create suitable breeding places for vector mosquitoes. Such sites provide habitats for diversified
naturally occurring microbiota. Ciliated protists, Zoothamnium sp., Chilodonella sp., and Vorticella microstoma are among
such microbiota found in vector mosquito habitats especially in rice field habitats in Sri Lanka. The present study was car-
ried out to determine the comparative larvicidal effect of these ciliated protists collected from naturally infested mosquito
larvae in some rice-field habitats in Kurunegala, Sri Lanka, against vector mosquito larvae. Vector mosquito larvae, Culex
tritaeniorhynchus, and Culex gelidus were reared in the laboratory from field-collected water samples while Aedes aegypti
mosquito larvae were reared using egg sheets, for the laboratory bioassays. V. microstoma showed the potential for infec-
tion and mortality of Cx. tritaeniorhynchus larvae (71.33% ± 5.23). Results revealed a minimum of 1000 V. microstoma is
required to kill a single third instar larva of Cx. tritaeniorhynchus at 69.60 ± 2.40 h of exposure. Cx. gelidus larvae showed
41.33% ± 3.43 mortality due to V. microstoma infestation. However, none of the ciliates were effective against Ae. aegypti
larvae. Chilodonella sp. was very occasionally reported during this study hence was not possible to the mass rear for experi-
mentations. This study concludes that V. microstoma is an effective ciliated parasite of Cx. tritaeniorhynchus larvae. Due to
their effectiveness and eco-friendly nature, this species can be developed as an effective bio-controlling agent against Cx.
tritaeniorhynchus mosquito species.
