Medicine
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This repository contains the published and unpublished research of the Faculty of Medicine by the staff members of the faculty
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Item Effect of larval nutritional regimes on morphometry and vectorial capacity of Aedes aegypti for Dengue transmission(BioMed Research International, 2019) Gunathilaka, N.; Upulika, H.; Udayanga, L.; Amarasinghe, D.BACKGROUND: Nutritional level in larval diet of mosquito vectors influence on life history traits and vectorial capacity (VC). Therefore, the present study was carried out to assess the effect of larval diet concentration on vector bionomic and VC of Aedes aegypti in Sri Lanka. Method. Three batches of 400 Ae. aegypti larvae (first instar) were reared under different concentrations of larval diet (6%, 8%, and 10%; Volume/Volume), which was prepared by mixing 12.5 g of tuna meal, 9.0 g of bovine liver powder, and 3.5 g of Brewer’s yeast, in 100 ml of distilled water. The effect of larval diet concentration on different morphometric and functional parameters of larvae (length and width of head, abdomen, survival rate, and pupation success), pupae (length and width of cephalothorax, survival rate, and adult emersion), adult (length and width of thorax, abdomen, survival rate, longevity, biting frequency and fecundity of adults) were examined. In addition, VC of Ae. aegypti was evaluated. The General Linear Model (GLM) was used for the statistical analysis. Results. Larval head length, head width, thoracic width, abdominal length, abdominal width, total length, and survival rate significantly increased with higher doses of larval diet (P<0.05). In case of pupae, length, and width of cephalothorax, survival rate and adult emergence rate denoted an increasing trend with the elevated larval diets. However, the variations of survival rate and adult emergence rate were statistically significant (P<0.05). In adults, all morphometric parameters (thoracic length, abdominal length, abdominal width, and wing length) significantly increased with elevating larval diets levels (except for thoracic width) along with the biting frequency, fecundity, and survival rate (P<0.05) of adult females. The VC also denoted significant variations (F4,14 = 24.048; ) with the larval diet concentration, whereby the highest VC of 196.37 was observed at 10% treatment. Conclusion. Larval food availability has a significant influence on the adult fitness and thus may affect the incidence of dengue due to variations in the VC of Ae. aegypti. Hence, this investigation highlights the requirement in accounting the environmental variation at the larval stages in order to understand transmission dynamics and control of dengue in Sri Lanka.Item Malarial vectors in an irrigated rice cultivation area in southern Sri Lanka(Oxford University Press, 2005) Premasiri, D.A.; Wickremasinghe, A.R.; Premasiri, D.S.; Karunaweera, N.Entomological surveys were carried out from March 1998 to December 1999 to study the prevalence, distribution and abundance of malarial vectors in relation to selected environmental factors and potential mosquito breeding sites in irrigation channels in 15 villages in the Lunugamvehera Irrigation and Settlement Project, a malaria-endemic area of southern Sri Lanka. Mosquito collections were made at monthly intervals using four sampling methods. Thirteen anopheline species were collected. Following monsoonal rains, anopheline breeding took place primarily in rainwater accumulations. During the inter-monsoonal period, pools formed in the irrigation system, semi-permanent pools formed as a result of rainfall and permanent ground pools were the major breeding sites of anophelines. Very little anopheline breeding took place within the irrigation channels. Amongst the seven anopheline species collected from human dwellings, Anopheles subpictus was the most prevalent, followed by A. culicifacies; together these two species comprised more than 99% of the indoor resting population. The number of days of rain was an important macro-epidemiological factor influencing the density of malarial vectors. There was no consistent trend between the amount of water released or the number of days of water release from the reservoir and the outdoor or indoor resting densities of anophelines.