ICAPS 2022
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/25482
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Item Diversity of microbiota associated with dengue vector mosquito breeding habitats in Udapalatha MOH Division, Sri Lanka(Kumari J. Y.; Amarasinghe L. D.; Ranasinghe H. A. K.; (2021), Diversity of microbiota associated with dengue vector mosquito breeding habitats in Udapalatha MOH Division, Sri Lanka, Proceedings of the International Conference on Applied and Pure Sciences (ICAPS 2021-Kelaniya) Volume 2, Faculty of Science, University of Kelaniya Sri Lanka. Page 3., 2022) Kumari, J. Y.; Amarasinghe, L. D.; Ranasinghe, H. A. K.Microbiota associated with mosquito breeding habitats are among biotic factors and serve as parasites, pathogens, predators, competitors, non-competitors, and food items for developing larvae. Therefore, there are naturally occurring microbiota species that serve as potential controlling agents against mosquito larvae, causing lethal effects on them. This information can be used in developing novel mosquito vector control strategies. Besides, the degree of parasitic, pathogenic, or predatory effects may also vary with the geographical location, influencing environmental conditions, including abiotic factors and other biotic factors within the habitat. Therefore, the current study was carried out to determine the diversity of microbiota associated with different breeding habitats of dengue vector mosquitoes; Aedes aegypti and Ae. albopictus. Sampling was performed from a variety of breeding habitats at Udapalatha MOH division in Gampola urban area from November 2021 to January 2022. Microbiota in water samples were preserved using Rose Bengal solution and Lugol’s iodine and were identified under microscope, using standard identification keys. During the survey, twelve different breeding habitats, namely plastic containers, metal containers, concrete slabs, glassware, tires, leaf axils, tree holes, coconut shells, bamboo trees, ornamental ponds, discarded roof tiles and clay pots, were identified as key breeding sites of Aedes mosquitoes. From the collected samples 54.54% of habitats were positive for Ae. albopictus and 45.46% were positive for Ae. aegypti. Eleven microbiota species; Canthocamptus staphylinus, Canthocamptus sp., Parastenocaris sp., Lepadella ovalis, L. patella, Rotatoria rotatoria, Rotatoria sp., Asplanchna brightwelli, Trichocerca rattus, Euglena sp., and Flagilaria sp. were encountered from breeding habitats associated with Ae. aegypti. Meanwhile, Canthocamptus staphylinus, Parastenocaris sp., L. ovalis, L. patella, R. rotatoria, Rotatoria sp., Euglena sp. and Flagilaria sp. recorded from breeding habitats associated with Ae. albopictus. The highest Shannon Weiner diversity index and gamma diversity relating to the Ae. aegypti were recorded from leaf axils, while for Ae. albopictus, it was from metal containers. For Ae. aegypti, the highest heterogeneity in microbiota diversity was recorded from tire habitats and it was from plastic containers for Ae. albopictus. Out of the microbiota species recorded, no species was identified as parasitic or pathogenic to Aedes mosquito larvae. Updated information from the present investigation would facilitate implementing appropriate vector control interventions.Item Diversity of midgut symbiotic bacteria in Aedes mosquito genera: A meta-analysis(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Kumari, J. Y.; Amarasinghe, L. D.; Udayanga, N. W. B. A. L.; Ranasinghe, H. A. K.The gut bacterial composition of mosquitos has the capability of altering mosquito pathogen transmission through numerous mechanisms, which is useful in novel transmission control strategies. Therefore, understanding the diversity of gut bacteria in different mosquito genera is highly important. The present analysis was carried out to evaluate the variations in gut-bacteria in field-caught Aedes adult mosquitos from different geographical locations. A literature survey was conducted to identify quantitative data related to the midgut bacterial abundance in Aedes, using standard search terms and keywords. The collected data were arranged at the bacterial class level and were subjected to a square-root transformation. A resemblance matrix was constructed based on the Bray-Curtis resemblance. Cluster analysis followed by the Analysis of Similarities (ANOSIM) and Distance based Redundancy Analysis (dbRDA) were used for data analysis. Gut bacterial abundance from six different countries; Netherlands, USA, Sri Lanka, India, Brazil, and Panama, were used in the study. A total of 12 bacterial classes, were recorded and bacterial classes of Alphaproteobacteria and Gammaproteobacteria accounted for the highest abundance in Aedes mosquitoes from most of the countries. Interestingly, Aedes mosquitoes from Brazil, India and Sri Lanka, did not report the abundance of Alphaproteobacteria in their gut contents. Based on the Bray-Curtis similarity-based cluster analysis, four major clusters were identified at a similarity level of 48.9%, based on the overall abundance of bacterial classes. Aedes mosquitoes of Sri Lanka and India formed one cluster, sharing a similarity of 81.6%, while Brazil and Panama formed another cluster. Meanwhile, Aedes mosquitoes from Netherland and USA formed two separate clusters. The statistical significance of aforementioned clustering status was further verified by the Analysis of Similarities (ANOSIM), which reported a Global R value of 0.96. The clustering status suggested by the cluster analysis was further verified by the findings of the dbRDA. As indicated by the loadings of the dbRDA axes, the abundance of Gammaproteobacteria and Bacilli bacterial classes were found to be responsible for the similarity between gut bacterial diversity in Aedes mosquitoes from India and Sri Lanka. Further studies on the gut-microbial diversity of Aedes mosquitoes are recommended to support the implementation of novel vector control strategies in Sri Lanka.Item Larvicidal effect of extracellular extracts of Trichoderma longibrachiatum and Trichoderma viride against Aedes aegypti(Faculty of Science, University of Kelaniya Sri Lanka, 2022) Tharaka, W. G. H.; Perera, S. A. D. S.; Amarasinghe, L. D.; Wickramarachchi, S.Aedes aegypti is a potential vector for transmitting dreadful diseases such as yellow fever, ZIKA, dengue and chikungunya, leading to global health problems. However, there is no warranted controlling method for these diseases other than controlling the vector. Apart from destroying breeding sites, use of larvicides is also important in larval control of the vector. Synthetic chemical insecticides, which dominate mosquito control programmes, are hazardous and exert unwarranted toxicity on non-targeted organisms, and lead to develop physiological resistance in target insects. Therefore, environmentally friendly, fungal mediated insecticides have been a priority at present. In current study, larvicidal effect of extra cellular fungal extracts of Trichoderma longibrachiatum and Trichoderma viride against 3rd instar larvae of Ae. aegypti was investigated. The fungi were grown in Richard’s broth medium containing glucose, agar, potassium nitrate, potassium dihydrogen phosphate, magnesium sulphate and ferric chloride. Eighteen different test concentrations of extracellular fungal filtrates, in a range from 0.625gL-1to 175gL-1, were prepared and batches of 25 number of laboratory reared 3rd instar larvae of Ae. aegypti were exposed to each test concentration separately with three replicates. Control bioassays were conducted with distilled water and larval mortality was recorded after 24 and 48 hour exposure periods. Results revealed that extracellular extracts of T. viride exhibited high larvicidal activity against Ae. aegypti larvae compared to the larvicidal activity of T. longibrachiatum. LC50 values for 3rd instar larvae of Ae. aegypti at 24 hours to the extracellular extracts of T. viride and T. longibrachiatum were 99.92 gL-1 and 114.98 gL-1respectively whereas LC50 values at 48 hours of exposure to the extracellular extracts of T. viride and T. longibrachiatum were 92.46 gL-1 and 108.71 gL-1 respectively. This study concludes that extracellular fungal extracts of T. longibrachiatum and T. viride can act as potential larvicides against Ae. aegypti and they can be used as alternatives for hazardous synthetic insecticides.