Zoology
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Item Leishmaniasis: a vector- born disease in Sri Lanka: past, current and future(Gloria Scientiam – Golden Jubilee Commemorative Volume, Faculty of Science, University of Kelaniya, 2017) Ganehiarachchi, G.A.S.M; Nayakarathna, N.M.N.G.; Rajapakse, R.P.V.J.Leishmaniasis is caused by a protozoan parasite Leishmania species and is transmitted to humans by the bite of infected female phlebotomine (Diptera: Psychodidae) sand flies. There are three main forms of Leishmaniasis; Cutaneous Leishmaniasis, Muco-Cutaneous Leishmaniasis and Visceral Leishmaniasis. At present, Cutaneous Leishmaniasis is established in Sri Lanka. The parasite in this country is Leishmania donovani MON 37 and the prevalent vector is Phlebotomus argentipes. Environmental factors including temperature, humidity and rainfall influence the abundance and distribution of sand flies. Socio-economic conditions, population mobility, environmental and climate changes are the main risk factors of the spread of Leishmaniasis. Early detection of the disease and treatment, vector management and health education are the main control strategies for the control of the disease. It is a timely need to control the disease transmission before more virulent strains are established in the country. To resolve the epidemiology of Leishmaniasis further studies on the parasitic aspects and entomological studies of vector aspects are most important. Harmonizing with these biological phenomena, continuous surveillance, improving case detection programs at the community level and implementing management protocols and control activities are necessary to eliminate Leishmanisis in Sri LankaItem Some biological aspects and molecular variations in frigate tuna, Auxis thazard of the coastal waters around Sri Lanka(Journal of the National Science Foundation of Sri Lanka, 2019) Herath, D.; Perera, H.; Hettiarachchi, G.Auxis thazard (frigate tuna), is a commercially important fish species in Sri Lanka. Although Sri Lanka is fortunate to have a large resource of tuna, little information is available on the biology, genetics and stock structure of A. thazard. Hence, the present study was conducted to study the biology, genetics and stock structure of A. thazard in coastal waters around Sri Lanka. The fish samples were collected from October 2015 to September 2017 from day-boats operating in the Western, North Western, Eastern and Southern Provinces of Sri Lanka. For this period, the length-weight relationship and Fulton’s condition factor (K) calculated for A. thazard using standard length measured in centimetres and weight measured in grams were shown as W = 0.1091L 3.3385 and 1.93, respectively, indicating a relatively healthy growth pattern and a comparatively unpolluted habitat. Studies on the stomach contents revealed that A. thazard are non-selective carnivors, feeding on diverse animal prey items such as small fish species, shrimps and cephalopods available in the surrounding waters. The fecundity of female A. thazard was shown to be 48,056 to 267,000 eggs. The calculated GSI values showed that the peak spawning period for male A. thazard extends from May to August and for the females from May to July. The phylogenetic analysis of the mitochondrial D-loop region sequences of 75 selected samples representing all the geographical regions studied showed that the fish of different regions are clustering together. Hence, for fisheries management strategies, A. thazard found in the coastal waters of the Western, North Western, Eastern and Southern Provinces of Sri Lanka could be considered as a single stock.Item Habitat related variations and comparison of fatty acid composition of muscle and stomach contents of secondarily colonized Malabar Sprat (Ehirava fluviatilis) in Sri Lanka(NeBIO, An International Journal of Environment and Biodiversity, Vol.10(3), pp.152-163, 2019) de Zoysa, H.K.S.; Amarasinghe, U.S.; Edirisinghe, E.M.R.K.B.; Sundarabarathy, T.V.Ehirava fluviatilis is a marine origin clupeid found in Southern India and Sri Lanka, also found in two freshwater lakes, namely Parakarama Samudraya and Rajanaganaya reservoir, and that places are identified as secondarily colonizedhabitats. The objectives of this study were carried toinvestigate the fatty acid (FA) profile in the flesh of E.fluviatilis, to investigate the FA profile in the food of E. fluviatilis, and identify the impactof the FA profiles for colonisation. The Bligh and Dyer extracting method was used to lipids extraction of flesh and stomach contents of E. fluviatilis and Gas Chromatography (GC) was used to identify the different types of FAs. Data were statistically analyzed to examine the differences in the quantities of different FAs using ANOVA and principal component analysis (PCA). The predominant FAs were recorded in two different habitats ofE. fluviatilis in both flesh) and stomach contents. The only recorded difference between FAs profile was the presence of C 18:2 (n-4) in the Rajanganaya reservoir. The difference in the FA profile may lead to colonization of marine origin E. fluviatilis in Rajanganaya reservoir as a freshwater lacustrine habitat due to the ability of modification of FAs. Further, this study also indicates that the presence of specific FAs could be used as biomarkers to identify species.Item Diagnosis of Vespa affinis venom allergy:use of immunochemical methods and a passive basophil activation test(Allergy, Asthma & Clinical Immunology, 2019) Gunasekara, P.; Handunnetti, S.M.; Premawansa, S.; Kaluarachchi, P.; Karunatilake, C.; Ratnayake, I.P.; Dias, R. K. S.; Premakumara, G. A. S.; Dasanayake, W. M. D. K.; Seneviratne, S.L.; de Silva, R.Background: Allergy to Vespa affinis venom is common in the Asia Pacific region. Venom preparations for diagnosis are not commercially available for this species. Methods: The prominent allergens in V. affinis venom were identifiedusing immunochemical methods. Use of ImmunoCAP of Vespula vulgaris crude venom/its components and a passive basophil activation test (BAT) in the diagnosis of patients who had anaphylaxis to V. affinis venom (n = 30) were also accessed. The IgE double-positivity rates (positive to both hornet and honeybee) in ImmunoCAP and the passive BAT were determined. Results: High IgE reactivity was seen with the five allergens in V. affinis venom; 96% (29/30) for 34 and 24 kDa, 93% (28/30) for 45 kDa and 90% (27/30) reactivity for the 100 and 80 kDa respectively. IgE cross-reactivity was low with ImmunoCAP using V. vulgaris venom (43%; 13/30) and Ves v1 (3%; 1/30), but relatively high with Ves v5 (73%; 22/30). All patients (100%) were positive to V. affinis venom in passive BAT. In ImmunoCAP, a high double-positivity rate (76%; 23/30) was detected while no double-positivity was detected in passive BAT. Conclusions: High IgE reactivity for five allergens of V. affinis points to the potential of using these allergens in component resolved diagnosis (CRD). The passive BAT has shown its importance as a promising diagnostic tool with high accuracy. It would be particularly useful in cases with doubtful double-positive results of other diagnostic tests.Item Effects of a gel bait on the suppression of noxious Crematogaster rogenhoferi Mayr, 1879 (Formicidae: Myrmicinae) in Sri Lanka(Caucasian Entomological Bulletin, Vol. 15. No.2., 2019) Dias, R.K.S.; Udeshika, K.G.I.Crematogaster rogenhoferi Mayr, 1879 in a home garden in Sri Lanka was reported to cause health hazards and an investigation was conducted from February to November in 2016 to list the tree species bearing its nests and to record the nest structure, nest intensity and colony demography for the evaluation of its level of infestation and to recommend a method for the suppression of its population size. Three types of nests on 19 tree species were recognized. The largest nest had all life stages. The standard laboratory experiment conducted with the provision of 0.25 g of Optigard Ant Gel bait (OAG) showed 68% of mean mortality of workers. A field experiment conducted by applying separate 1 cm band of OAG and honey at 10 cm and 1 cm distance from three initial stage nests and a honey band only at 1 cm distance from three control nests recorded a significantly higher 89.2% of mean mortality of workers. Two mature nests treated with OAG similarly while two other similar nests served as simultaneous control nests resulted significantly higher 97.5% of mean mortality of workers and queens in OAG-treated nests, after 24 hours. Hence, application of 1 cm band of OAG on the tree trunk, if essential, is recommended as a method for suppressing the population size of C. rogenhoferi in a home garden.Item Influence of hydrology on water quality and trophic state of irrigation reservoirs in Sri Lanka(Lakes & Reservoirs: Science, Policy and Management for Sustainable Use, 2019) Nadarajah, S.; Wijenayake, W.M.H.K.; Amarasinghe, U.S.Many reservoirs provide multiple benefits to people around the world, in addition to primary uses such as irrigation. Thus, reservoir management should address their multiple uses. The water quality of ten irrigation reservoirs in Sri Lanka was examined in the present study with the objective of better understanding the effects of hydrological regimes on reservoir water quality and trophic state. Basic limnological parameters pertinent to the nutrient loads to, and trophic state of, the reservoirs were collected from June 2013 to February 2016. The sampling period was arbitrarily divided into two periods of approximately similar duration (period 1 = June 2013–September 2014; period 2 = October 2014–February 2016) to investigate whether or not there was a seasonal variation in the water quality parameters. Although temporal and spatial variations were observed, most water quality parameters were within the levels acceptable for drinking water standards. The 10 reservoirs were also ordinated by principal component analysis (PCA) on the basis of the water quality parameters of the two sampling periods in a two‐dimensional score plot. Reservoirs in the first principal component (PC1) axis were represented by negative scores attributable to the dissolved oxygen concentration and pH and, to a lesser extent, by electrical conductivity and chlorophyll‐a concentration. Positive scores in PC1 were represented by reservoirs with a score loading attributable to alkalinity, nitrate concentration, Secchi depth, temperature and seston weight and, to a lesser extent, from the total phosphorus concentration. There was a significant negative correlation of PC1 scores with relative reservoir water‐level fluctuation (RRLF; the ratio of mean reservoir waterlevel amplitude to mean reservoir depth). Furthermore, Carlson's trophic index also were influenced by RRLF, although not by hydraulic retention time (HRT), indicating allochthonous nutrient inputs into the irrigation reservoirs were mainly governed by RRLF, but not by HRT. Thus, the results of the present study provide useful insights into achieving desirable reservoir water quality through the manipulation of the hydrological regime.Item Comparison of trophic structure of fish assemblages in two tropical steams in Sri Lanka: a seasonal dry zone stream and a perennial wet zone stream(International Review of Hydrobiology, 2019) Weliange, W.S.; Amarasinghe, U.S.; Vijverberg, J.; Leichtfried, M.; Füreder, L.Most tropical rivers especially in the Asian region, are severely impacted by various human perturbations, and the diverse habitats in streams support rich invertebrate and vertebrate communities. It is hypothesized that the fish assemblages and their dietary structure in two tropical streams differ because they flow through different terrains and are exposed to different climatic conditions. In the wet zone stream, which is geomorphological more complex, fish faunal diversity showed significant longitudinal variations, and sustains endemic fish species. In the diets of fish, taxonomic composition was different along the longitudinal gradients, but dietary taxa richness in the two streams was virtually similar having 32 dietary taxa in wet zone stream and 36 taxa in dry zone stream. In the wet zone stream, we observed a lower proportion of specialist feeding species than those in the dry zone stream. Trophic indices of individual species in fish assemblages ranging from herbivory to carnivory also indicate structuring of fish communities along the longitudinal gradients of the two streams based on dietary structure. The main differences between the fish assemblages in the wet zone compared to the dry zone were the higher number of endemic species and the lower percentage of specialist feeders with higher trophic indices. The outcome of this study hopefully contributes to plan future biodiversity conservation management schemes under various river basin development strategies.Item Dietary Guild Structure in Fish Assemblages and Trophic Position of Constituent Species in Brush Parks of a Tropical Estuary(Asian Fisheries Society, 2019) Gammanpila, M.; Amarasinghe, U.S.; Wijeyaratne, M.J.S.Trophic guild structure and dietary niche breadth in tropical fish communities are important to identify functional groups and to understand how trophic positions of constituent species help coexistence. Objective of the present study was to investigate whether the constituent species of fish assemblages in brush parks could be grouped into trophic guilds and how these species contribute to structure the fish community along trophic dimensions. Diets of 46 fish species caught in brush parks were analysed and the food items were categorised into 11 broad groups. Based on the composition of diets, fish were grouped into 8 trophic guilds. Levin’s index of niche breadth indicated that the constituent species in the trophic guilds for which food was abundant, were generalists, whereas the trophic guilds of higher trophic levels were specialists. Within each trophic guild, constituent species showed different trophic indices indicating low inter-specific competition resulting in optimum food resource utilisation.Item Comprehensive evaluation of demographic,socio-economic and other associated risk factors affecting the occurrence of dengue incidence among Colombo and Kandy Districts of Sri Lanka: a cross-sectional study(Parasites & Vectors (2018) 11:478, 2018) Udayanga, L.; Gunathilaka, N.; Iqbal, M.C.M.; Lakmal, K.; Amarasinghe, U.S.; Abeyewickreme, W.Background: Comprehensive understanding of risk factors related to socio-economic and demographic status and knowledge, attitudes and practices (KAP) of local communities play a key role in the design and implementation of community-based vector management programmes, along with the identification of gaps in existing control activities. Methods: A total of 10 Medical Officers of Health (MOH) areas recording high dengue incidence over the last five years were selected from Colombo (n = 5) and Kandy (n = 5) Districts, Sri Lanka. From each MOH area, 200 houses reporting past dengue incidence were selected randomly as test group (n = 1000 for each district) based on the dengue case records available at relevant MOH offices. Information on socio-economic and demographic status and knowledge, attitudes and practices were gathered using an interviewer administered questionnaire. The control group contained 200 households from each MOH area that had not reported any dengue case and the same questionnaire was used for the assessment (n = 1000 for each district). Statistical comparisons between the test and control groups were carried out using the Chi-square test of independence, cluster analysis, analysis of similarities (ANOSIM) and multidimensional scaling (MDS) analysis. Results: Significant differences among the test and control groups in terms of basic demographic and socio-economic factors, living standards, knowledge, attitude and practices, were recognized (P < 0.05 at 95% level of confidence). The test group indicated similar risk factors, while the control group also shared more or less similar characteristics as depicted by the findings of cluster analysis and ANOSIM. Findings of the present study highlight the importance of further improvement in community education, motivation and communication gaps, proper coordination and integration of control programmes with relevant entities. Key infrastructural risk factors such as urbanization and waste collection, should be further improved, while vector controlling entities should focus more on the actual conditions represented by the public on knowledge, attitudes and personal protective practices. Conclusions: The design of flexible and community friendly intervention programmes to ensure the efficacy and sustainability of controlling dengue vectors through community based integrated vector management strategies, is recommended.Item On the retirement of an eminent scientist in fisheries and aquatic science in Sri Lanka: a personal approach(Sri Lanka J. Aquat. Sci. 23(1) (2018): 1-2, 2018) Amarasinghe, U.S.The current issue of Sri Lanka Journal of Aquatic Sciences is dedicated to Professor M.J.S. Wijeyaratne (Department of Zoology & Environmental Management, University of Kelaniya, Sri Lanka) for his 40 years of uninterrupted contribution to research on fisheries and aquatic sciences in Sri Lanka. After his secondary school education at Royal College, Colombo, he entered the University of Sri Lanka, Vidyalankara Campus and was graduated with BSc Special degree in Zoology in 1975 with a Second Class Upper Division Honours. After joining the Vidyalankara Campus of the University of Sri Lanka (presently University of Kelaniya) as a probationary lecturer in 1976, he won the Fulbright scholarship and obtained MSc degree in the field of Natural Resources from University of Michigan, USA in 1978 and subsequently PhD from University of Kelaniya in 1984. During his career, Professor Wijeyaratne has so far authored 100 research papers in indexed journals and scholarly volumes, 14 textbooks and edited volumes, 97 research communications and also contributed as a consultant for 81 development projects both in Sri Lanka and overseas. University of Kelaniya has recently celebrated 50th anniversary of the Faculty of Science. After establishment of the Faculty of Science in this university in 1967, the research culture in the Sri Lankan university system has moved towards a new paradigm, especially in the field of fisheries and aquatic sciences. Professor H.H. Costa, the founder Professor of Zoology in the University of Kelaniya (then Vidyalankara University) was instrumental to make the Department of Zoology in University of Kelaniya the Centre of Excellence in research on fisheries and aquatic sciences in Sri Lanka. Professor Wijeyaratne was the first BSc Honours