Gampaha District Research Articles

Early Recognition of Rainfall to Plan and Manage the Cultivation: A Forecasting Model Using Artificial Neural Networks for Dompe Divisional Secretariat in Gampaha District, Sri Lanka

As the agricultural productivity is climate sensitive, forecasting climatic factors is important to maximize the harvest and to planning and management of the cultivation. Even though all the climatic factors have influence on cultivation, rainfall is one of the major influential factor to Sri Lankan agriculture. Rainfall forecasting is vital in agriculture and it is a challenging task due to the uncertainty of natural phenomena. Artificial neural network (ANN) approach is being applied for forecasting real time rainfall using climatic factors affecting to rainfall. The aim of this study was to identify a neural network model which is capable of forecasting rainfall of Dompe Divisional Secretariat in Gampaha District with a high accuracy. Feed forward neural network model (FFNN) was applied with Levenberg-Marquardt back propagation algorithm and the network parameters were adjusted to minimize the forecasting error. The suggested FFNN model consisted of 12 input variables with two hidden layers with 13 and 10 hidden neurons in first and second layers, respectively. Log sigmoid transfer function used in hidden layer 1 and 2 while pure linear transfer function was used in the output layer. The model forecasts rainfall with mean squared error of 0.0895 and normalized mean squared error of 0.1975. The coefficient of determination (R²) of the testing set was 0.8. These results demonstrated the suitability of other climatic factors: temperature, wind speed, air pressure, humidity, percentage of clouds and their lags in forecasting rainfall using ANN technique in forecasting rainfall with high accuracy.

Multivariate spatio-temporal approach to identify vulnerable localities in dengue risk areas using Geographic Information System (GIS)

Dengue is one of the most important vector-borne infection in Sri Lanka currently leading to vast economic and social burden. Neither a vaccine nor drug is still not being practiced, vector controlling is the best approach to control disease transmission in the country. Therefore, early warning systems are imminent requirement. The aim of the study was to develop Geographic Information System (GIS)-based multivariate analysis model to detect risk hotspots of dengue in the Gampaha District, Sri Lanka to control diseases transmission. A risk model and spatial Poisson point process model were developed using separate layers for patient incidence locations, positive breeding containers, roads, total buildings, public places, land use maps and elevation in four high risk areas in the district. Spatial correlations of each study layer with patient incidences was identified using Kernel density and Euclidean distance functions with minimum allowed distance parameter. Output files of risk model indicate that high risk localities are in close proximity to roads and coincide with vegetation coverage while the Poisson model highlighted the proximity of high intensity localities to public places and possibility of artificial reservoirs of dengue. The latter model further indicate that clustering of dengue cases in a radius of approximately 150 m in high risk areas indicating areas need intensive attention in future vector surveillances.

How would Widespread Community Transmission of Covid-19 in Sri Lanka look like? A Population-based Simulation

Abstract Widespread community transmission of Covid-19 can overwhelm the capacity of health systems; Sri Lanka is no exception. We simulated the widespread community transmission of Covid-19 in Sri Lanka, using the Susceptibility, Infected and Removed (SIR) model through the Penn State University CHIME Model incorporated to ArcGIS Pro, by introducing one case of Covid-19 to the current population in each of the 26 health districts and running the model for 365 days. The simulation revealed that the number of patients requiring admissions, ICU care, and mechanical ventilation would peak at 1942, 583, and 388 per day, respectively, around 213 days from the onset. The cumulative number of cases needing admission, ICU care, and ventilation will be 245,916, 73,775, and 49,183 after 365 days. Colombo and Gampaha districts will report the highest number of daily total numbers of hospitalized cases over 1680. Health authorities can use the results of such simulations to prepare to face the worst-case scenarios of the Covid-19 outbreak to minimize morbidity and mortality. Keywords: Covid-19, Community Transmission, SIR Model, CHIME, Outbreak, Simulation, Prediction

Species composition and diversity of ant fauna (Hymenoptera: Formicidae) observed throughout a Yala season growing cycle of paddy fields in Gampaha District, Sri Lanka

Species composition and diversity of ant fauna (Hymenoptera: Formicidae) observed throughout a Yala season growing cycle of paddy fields in Gampaha District, Sri Lanka

Sustainable Alternative Wetland Management Strategy for Kalu Oya and Mudun Ela Basins of Sri Lanka

As a tropical island, Sri Lanka has highly diversified wetlands. Even though, the wetlands in the Western Province of Sri Lanka are highly rich in biodiversity, they are endangered due to the human development processes. Consequently, the sustainability of the wetlands and the economic and social life of the settlers who settle near and in the wetlands are significantly destructed. Due to the population growth and the rapid infrastructure development, the wetlands have been shrunken. Many land hungers have been emerged during the process of the city development and Megapolis. In this dichotomy, creating a policy framework on the wetlands is vital. There are two major objectives of the study, first, to describe the current impacts of socio-economic activities to the wetlands; second, to propose sustainable alternatives for preparation of the wetland management strategy for Kalu Oya and Mudun Ela Basins which are in the southwestern part of Gampaha District in Sri Lanka. The used strategies of the survey are fivefold: case studies of each sub catchment, measuring land use changes using secondary data and verified by the field visits, questionnaire survey for primary quantitative data, field observations, and focused group discussions for qualitative data. Even though, they are the two basins of the Kelani River which is 145 km long being the fourth longest river in Sri Lanka which are also highly fragile sub catchments of the main catchments of the River. More than 80 percent of the neighboring settlers and settlers of wetlands do not know the significance and uniqueness of the wetlands and their life support services to the human beings and the other ecological services of these wetland ecosystems. Economic activities of all the wetlands are approximately equal and the usage of wetlands has been transforming from agricultural to industries and small services.

Awareness of harmful effects on tobacco smoking among adult male smokers in Sri Lanka: a cross sectional study

Background: Smoking of tobacco products is the second major cause of morbidity and mortality in worldwide. The objective of this study was to evaluate the awareness of the harmful effects on tobacco smoking among adult male smokers and their spouses in Sri Lanka.Methods: A cross sectional study was conducted among adult male smokers in Gampaha district was recruited. An interviewer administered questionnaire inquired participants' awareness about diseases caused by smoking.Results: Majority of participants (95.3%) were aware of the adverse effects of tobacco consumption on health. A total of 93.4% had knowledge that smoking is harmful to others. Majority of male smokers were aware of adverse effects on respiratory, cardiac and circulatory systems. However, the awareness of the association between impotence, infertility, birth defects and premature births with smoking is low in smokers.Conclusions: Majority of smokers have sufficient knowledge of harmful effects on health from smoking. Community awareness programs of adverse effects must be held targeting all the population including school children. Anti-smoking campaigns must be initiated in a broad manner, specially targeting the smoking population.

Factors Influencing Fertilizer Usage by Medium and Large Scale Coconut Farmers in Gampaha District, Sri Lanka

Aims: This study attempts to identify the factors affecting the usage of fertilizer by medium- and large-scale coconut farmers in the Gampaha District, Sri Lanka with a view to recommend pragmatic strategies to increase coconut production in Sri Lanka.
 Study Design: Multistage quota sampling with a proportion allocation method.
 Place and Duration of Study: The study was conducted during the year 2017 in the Gampaha administrative district, which is a leading coconut-producing region, under the coconut triangle of Sri Lanka. 
 Methodology: Both primary and secondary data were utilized in the study. Descriptive analytical techniques, factor analysis, and Binary Logistic Regression techniques were used in the data analysis.
 Results: The factor analysis disclosed five-factor groups that cumulatively explain 55% of the total variation. Binary Logistic Regression revealed that the prevalence of favorable weather patterns, usage of supplementary materials, availability of credit facilities, and organic fertilizer application significantly affect the application of inorganic fertilizer for coconut cultivation. The availability of a fertilizer subsidy, practicing moisture conservation, practicing animal husbandry, and applying inorganic fertilizer significantly determined the application of organic fertilizer for coconut cultivation. Usage of supplementary materials, yield of the last coconut picking, and household size significantly affected the fertilizer application for coconut cultivation in general.
 Conclusion: Prevalence of favorable weather patterns, supplementary materials, and credit usage increase the chance of applying inorganic fertilizer for coconut. Organic fertilizer application decreases the likelihood of applying inorganic fertilizer for coconut. Availability of a fertilizer subsidy, practicing moisture conservation, practicing animal husbandry increase the chance of applying organic fertilizer for coconut, whilst the inorganic fertilizer application decreases the likelihood of applying organic fertilizer for coconut.

Study on the Impact of National Policy Framework on the Performance of Small and Medium Enterprises (SMEs) in Gampaha District

SMEs in Sri Lanka steers the Sri Lankan economy as they increase gross domestic product and employment opportunities. With the past statistical data, it was indicated that a mixture of success and failure are faced by SMEs as a result of the current economic situation. So as a supportive partner, the government has given a number of opportunities and reliefs to overcome the failures faced by SMEs. Hence, the main purpose of this study is to investigate the effect of the national policy framework on the performance of small and medium enterprises in Gampaha District, Sri Lanka by analyzing the national policies formulated by the Sri Lankan government. Data were collected using questionnaires and interviews for the study. It was found out that there is a significant relationship between National Policy Framework and SME’s performance in Sri Lanka. The study will provide guidance to all relevant authorities including the government of Sri Lanka in identifying the application of policies designed and in making corrective actions. Further, this study offers some relevant recommendations to policymakers to implement better policies that are more favourable for business owners.

Molecular Characterization of Culturable Aerobic Bacteria in the Midgut of Field-Caught Culex tritaeniorhynchus, Culex gelidus, and Mansonia annulifera Mosquitoes in the Gampaha District of Sri Lanka.

Background Larval and adult mosquito stages harbor different extracellular microbes exhibiting various functions in their digestive tract including host-parasite interactions. Midgut symbiotic bacteria can be genetically exploited to express molecules within the vectors, altering vector competency and potential for disease transmission. Therefore, identification of mosquito gut inhabiting microbiota is of ample importance before developing novel vector control strategies that involve modification of vectors. Method Adult mosquitoes of Culex tritaeniorhynchus, Culex gelidus, and Mansonia annulifera were collected from selected Medical Officer of Health (MOH) areas in the Gampaha district of Sri Lanka. Midgut lysates of the field-caught non-blood-fed female mosquitoes were cultured in Plate Count Agar medium, and Prokaryotic 16S ribosomal RNA partial genes of the isolated bacteria colonies were amplified followed by DNA sequencing. Diversity indices were used to assess the diversity and richness of the bacterial isolates in three mosquito species. The distribution pattern of bacterial isolates between different mosquito species was assessed by Distance-Based Redundancy Analysis (dbRDA). Results A total of 20 bacterial species (Staphylococcus pasteuri, Bacillus megaterium, Staphylococcus cohnii, Pantoea dispersa, Staphylococcus chromogenes, Bacillus aquimaris, Staphylococcus arlettae, Staphylococcus sciuri, Staphylococcus warneri, Moraxella osloensis, Enterobacter sp., Klebsiella michiganensis, Staphylococcus hominis, Staphylococcus saprophyticus, Streptomyces sp., Bacillus niacin, Cedecea neteri, Micrococcus luteus, Lysinibacillus sphaericus, and Bacillus licheniformis) were identified. All of these species belonged to three phyla, Proteobacteria, Firmicutes, and Actinobacteria, out of which phylum Firmicutes (71.1%) was the most prominent. The least number of species was recorded from Actinobacteria. The relative distribution of midgut microbes in different mosquito species differed significantly among mosquito species (Chi-square, χ2 = 486.091; df = 36; P ≤ 0.001). Midgut microbiota of Cx. tritaeniorhynchus and Cx. gelidus indicated a similarity of 21.51%, while Ma. annulifera shared a similarity of 6.92% with the cluster of above two species. The gut microbiota of Cx. tritaeniorhynchus was also significantly more diverse and more evenly distributed compared to Ma. annulifera. Simpson's diversity, Margalef's diversity, and Menhinick's diversity indices were higher in Cx. gelidus. Of the recorded species, P. dispersa and strains of nonpathogenic species in Bacillaceae family (B. megaterium, B. niacini, B. licheniformis, and L. sphaericus) can be recommended as potential candidates for paratransgenesis. Conclusion The relative distribution of midgut microbes in different mosquito species differed significantly among the three studied adult mosquito species. The present data strongly encourage further investigations to explore the potential usage of these microbes through paratransgenic approach for novel eco-friendly vector control strategies.

Breeding Habitat Distribution of Medically Important Mosquitoes in Kurunegala, Gampaha, Kegalle, and Kandy Districts of Sri Lanka and Potential Risk for Disease Transmission: A Cross-Sectional Study.

Some arbovirus infections, especially dengue, have increased rapidly over the last few decades in Sri Lanka. Prevalence and distribution of different mosquito species have been limitedly documented, which remains grossly inadequate in providing evidence for potential health risks. In this study, the diversity and species composition of mosquitoes in four selected districts in Sri Lanka (Kurunegala, Gampaha, Kegalle, and Kandy) were investigated. Entomological surveys were conducted from a total of 160 temporary and permanent mosquito breeding habitats identified in the study area from June 2017 to October 2018. Mosquito immature stages were sampled using standard dipping, siphoning, or pipetting methods and identified up to the species level. Percentage relative abundance and habitat characteristics such as species richness, dominance, and Shannon–Weiner diversity were calculated for each surveyed habitat type. Associations between co-occurring species were estimated by Hulbert's coefficient of interspecific association (C8). A total of 4663 mosquito larvae belonging to seven genera and fifteen species of mosquitoes were collected. The relative distribution of mosquito species differed significantly among the four studied districts (X2 = 143.248; df = 33; P < 0.001). According to Kruskal–Wallis statistics (P < 0.05 at 95% of significance), all diversity indices for immature stages of medically important mosquitoes varied significantly across different breeding sites. Paddy fields had the significantly highest species richness of 4.0 ± 2.82. The coefficients of interspecific association among all the recorded medically important vector mosquitoes were found negative during the present study. The findings of the current study would be useful to identify the entomological potential for disease transmission and facilitate the implementation of appropriate vector control interventions. This would ultimately provide an avenue to improve the personal skills of health staff rather than limiting their knowledge to specified disease vectors, under which the control program is concerned.

Patterns and predictors of mortality in a semi-urban population-based cohort in Sri Lanka: findings from the Ragama Health Study.

ObjectiveTo describe patterns and predictors of mortality in a semi-urban population in Sri Lanka.DesignA prospective population-based cohort study.SettingRagama Medical Officer of Health area in the Gampaha district, Sri Lanka.ParticipantsAdults between 35 and 64 years of age were recruited using an age stratified random sampling technique in 2007.MeasuresAt baseline, we recorded socio-demographic, lifestyle, anthropometric, biochemical and clinical data of the participants. Over 10 years, we obtained the cause and date of death from the death registration documents of deceased participants. We determined the survival probability of the cohort over 10 years and estimated Hazard ratios (HRs) for all-cause mortality (ACM), cardiovascular mortality (CVM) and cancer-related mortality (CRM) using Cox’s proportional hazards model. We also estimated the survival probabilities for men and women in each 10-year age group and standardised mortality ratio relative to the source population.ResultsThere were 169 deaths over 10 years with standardised mortality rates of 5.3 and 2.4 per 1000 years of follow-up for men and women, respectively. Independent predictors of: ACM were older age, lower income, smoking and diabetes mellitus while gender, education, occupation, harmful alcohol use, waist circumference and hypertension were not; CVM were older age, lower income, smoking, diabetes and hypertension while gender and harmful alcohol use were not; CRM was older age while gender, smoking and diabetes were not. Those engaged in clerical and technical occupations or unemployed had a lower risk of CRM as compared with those engaged in elementary occupations.ConclusionsOlder age, lower income, smoking, diabetes and hypertension strongly predict mortality in this cohort. Addressing the identified modifiable predictors through behavioural modification will improve longevity in similar populations.

Performance Assessment of Sri Lankan Pre-Hospital Ambulance Service

Ischemic heart disease is the leading cause of mortality that raised the demand for pre-hospital emergency care in Sri Lanka. Understanding the performance of Sri Lanka's 1990 Suwa Seriya ambulance service is essential to improve its quality and to reduce morbidity and mortality associated with the disease. This study aims to describe socio-demographic characteristics and evaluate the clinical assessment and management process of patients presenting with acute chest pain of cardiac in origin. A descriptive study was conducted in Gampaha District of the Western Province of Sri Lanka. A total of 154 records of patients with acute chest pain who rang the 1990 call centre over a 3-month period were selected. Composite values for treatment and examinations as a percentage were plotted on run charts to assess the performance and its variations over the study period. About 47.4% of the study group were in 35–65 age group, 53.2% were males, and 81.8% had a typical presentation. The median for composite value for examination as a percentage was 89.5%, indicating substantial control and alignment with the reference package with normal cause variation. The median composite value for treatment as a percentage was 9.96%, a low value with normal cause variation. A good control of the processes of clinical examination and treatment is apparent. A higher median for composite value for examination as a percentage attributed to the formal training process of the ambulance staff. Although a low median was obtained for the composite value for treatment as a percentage, it was stable and pointed room for improvement.

Floristic Survey of Meethirigala Forest Reserve in Gampaha District

Meethirigala forest reserve consists of approximately 384 ha. It is the largest forest reserve in Gampaha District managed by the Forest Department. It has different topographic positions such as ridges, midslopes and valley areas close to the Kelani River. The present study was conducted to enumerate plant species found in all three topographic positions of the reserve. Plots were demarcated purposively to sample woody perennials equal or greater than 5 cm dbh (diameter at breast height) in 18 plots (5×100 m, rectangular shape). Seedlings greater than 1 m tall were sampled in 18 plots (5×5 m). Shannon diversity indices were calculated to compare dominance of particular species in different topographic positions. A total of 360 individuals of woody perennials belonging to 73 species in ridge, 368 individuals of woody perennials belonging to 100 species in midslope and 272 individuals of woody perennials belonging to 69 species in valley were recorded. And 132, 123 and 100 individuals of seedlings were enumerated in ridge, midslope and valley respectively. In ridge 58 generas, 28 families, in midslope 83 generas, 35 families and, in valley 68 generas, 29 families were observed. 28 species were found in all three different altitudes of the reserve. Forest species in study sites gave a total of 138 plant species belonging to 113 tree species, 11 climber species, 14 shrub species, 109 generas and 46 families. Of this total 138 species, 34 (25%) species are endemic to Sri Lanka. Highest endemism was recorded in the ridge (41.6%). Stratification of the ridge showed a very similar pattern to a Dipterocarp forest type. Highest diversity was recorded in midslope (1.7290) and lowest recorded in ridge (1.5626) of the forest. 18 threatened species were observed (3-Endangered and 15-vulnerable species). As a conclusion, Meethirigala forest reserve can be considered as an important refuge for wet zone forest species.

Source apportionment of rainwater chemical composition in wet precipitation at Kelaniya in Sri Lanka

Rainwater quality is of utmost importance as it can be used to predict atmospheric quality which of course governs, to some extent, the health of the ecosystem. In this regard, the research reported here was to study chemical characteristics of precipitation in Kelaniya, Gampaha District, one of the most populated and most urbanized districts in Sri Lanka. This study was conducted during the period from 2012 to 2014, and wet precipitation was analyzed for pH, conductivity, Na+, NH4+, K+, Mg2+, Ca2+, F−, Cl−, NO3−, SO42−, Pb, Cu, Mn, Al, Zn, and Fe for a total of seventy-eight (78) samples. Volume-weighted average concentrations of the major ionic species present in precipitation samples were in the order of Na+ > Ca2+ > Cl− > SO42− > NH4+ > Mg2+ > NO3− > K+ > F−. Neutralization of the acidic species would take place due to the presence of NH4+ and CaCO3. When considering marine contribution, SO42−/Na+, Ca2+/Na+, and Mg2+/Na+ ratios are higher than the reference value suggesting that contribution of sources be possible other than marine. Among metallic constituents, the concentration of Al is the highest while that of Mn is the lowest. Significant correlation is observed among certain ions and elements (Ca2+, SO42−, Mg2+, Al, Cu, Fe, Zn, and H+) which indicates their source of origin and chemical interaction. This study reveals that chemical composition of rain water depends on both anthropogenic activities and natural phenomena.

Selenium content in Bg 350 variety of rice consumed by Sri Lankans

Selenium is considered as an essential micronutrient. The daily requirement of selenium is 55 µg. As a result, the World Health Organization (WHO) has drawn their attention to establish the micronutrient range of selenium, required by the human body. Report from China has shown that an ecological correlation exists with the selenium content in the soil and increased mortality due to cancer and cardiovascular diseases with light intake of selenium. This led to the interest in assessing the nutritional status of selenium. Rice is the staple food of Sri Lankans and studies on selenium content in rice grown in Sri Lanka have not been reported. The present study reports the selenium content in Bg 350 variety of rice and soil obtained from twelve districts (Gampaha, Colombo, Matara, Hambantota, Kegalle, Matale, Anuradhapura, Pollanaruwa, Kurunegalle, Puttalam, Ampara and Moneragalle), in Sri Lanka determined using Hydride Generation Atomic Absorption spectrometer (HGAAS). The results of the study showed that selenium content in rice and soil obtained from Gampaha and Colombo districts were very low and less than the detectable levels of the instrument (0.5 μg/kg). Except for rice and soil from Pollanaruwa district that had a very high selenium content in rice (61.2 μg/kg) and soil (69.8 μg/kg), the respective values from other districts were low [13.8 μg/kg (Kegalle) -6.3 μg/kg (Anuradhapura)] and [20.3 μg/kg (Matara) -9.5 μg/kg (Matale)].

Risk assessment and source apportionment of wet bulk deposition in three typical sites of Gampaha District, Sri Lanka

Scavenging of pollutants emitted to the atmosphere from natural resources and anthropogenic activities changes the chemical composition of rainwater. However, determination of the extent of atmospheric pollution and identification of pollution sources have not been regularly carried out in Sri Lanka. The objective of this research is therefore to analyze bulk deposition samples collected during a 7-month period from 10 June 2017 to 6 January 2018 in three different locations in Sri Lanka, Katunayake, Gampaha and Lunugama, followed by analysis of rainwater quality parameters including anions and cations using standard methods. These locations differ from each other in geography, industrialization and urbanization. Acid rain was not encountered in any of the three locations during the sampling period according to the pH measurements. The volume-weighted mean ion concentration in the three locations determined by ion chromatography varied as K+ < NH4+ < Mg2+ < Ca2+ < Na+. The dominant cations were Ca2+ and Na+, while Cl− and SO42− were identified as the dominant anions in all locations. The ratios between Na+ and the ions Cl−, SO42−, Ca2+, K+ and Mg2+, calculated using the enrichment factor, indicate that some ions from marine and anthropogenic activities contribute to the rainwater. The Katunayake sampling location showed the highest Pearson correlation between Na+ and Cl− because of the sea breeze, while Ca2+ and Mg2+ showed the highest Pearson correlation in the Gampaha and Lunugama locations because of soil dust. Although rainwater is not acidic according to pH measurements, it can be neutralized by calcium salts. This masking effect should thus be considered in risk assessment strategies. Continuous monitoring of rainwater quality is necessary to reach sound conclusions and make predictions about atmospheric quality.

Atmospheric chemical composition of bulk deposition at two geographically distinct locations in Sri Lanka.

This study presented the research work carried out for the investigation of chemical composition of bulk precipitation in two geographically and economically distinct areas, namely Gampaha and Kandy Districts. This study was conducted from 2013 to 2014 at three sampling stations in each District. The bulk precipitation was analyzed for pH, conductivity, Na+, NH4+, K+, Mg2+, Ca2+, F-, Cl-, NO3-, SO42-, Pb, Cu, Mn, Al, Zn and Fe for a total of 375 samples. Only 8% events of acidic precipitation were recorded in Gampaha District when compared with 3% in Kandy District. The volume weighted average concentrations of the major ionic species present in precipitation samples were in the order of Na+ > Ca2+ > Cl- > NH4+ > SO42- > Mg2+ > NO3- > K+ > F- in the Gampaha stations, while the order was NH4+ > Ca2+ > Na+ > Cl- > SO42- > Mg2+ > NO3- > K+ > F- in Kandy District. Neutralization of acidity of precipitation is much more related to CaCO3 than NH3, and high content of Ca2+ ions present in both Districts strongly supports this fact. When considering marine contribution, SO42-/Na+, Ca2+/Na+ and Mg2+/Na+ ratios are higher than the reference value suggesting contribution of sources other than marine. Depositions of both Districts show that the concentration of Al is the highest while that of Mn is the lowest. Principal component analysis suggests that influencing human activities on chemical composition of rain water depends on thermal power plant, oil refinery, heavy traffic and waste incineration in the study area.

A NEW DIMINUTIVE DAY GECKO SPECIES OF THE GENUS Cnemaspis STRAUCH, 1887 (REPTILIA : GEKKONIDAE) FROM PILIKUTTUWA, NEAR THE CAPITAL OF SRI LANKA

We investigated diminutive day geckos of the genus Cnemaspis in Sri Lanka, and based on morphological evidence, a new species belonging to the C. podihuna complex is described herein. The new species occurs in lowland wetzone (alt. 50 m a.s.l.) forests and adjacent human habitations which have a dense tree cover in Gampaha District, near Colombo, the capital of Sri Lanka. We also provide a key for this and previously recognized species from Sri Lanka, based on collected material and literature.

Field-based evaluation of novaluron EC10 insect growth regulator, a chitin synthesis inhibitor against dengue vector breeding in leaf axils of pineapple plantations in Gampaha District, Sri Lanka

BackgroundInsect growth regulators (IGRs) are considered a novel group of insecticides to control mosquitoes. Novaluron is an IGR with benzoylphenyl urea insecticide, which inhibits chitin synthesis in insects and can reduce insect population density; it is also known to have a high margin of safety for mammals.MethodsThe effective minimum concentration of novaluron formulation EC10 was tested. Six pineapple plantations [control (n = 3) and test (n = 3)] were selected from Meerigama Medical Officer of Health area in Gampaha District, Sri Lanka. Fifteen plots (10 × 10 m) were demarcated in each site with a 200 m distance apart. Leaf axils of 450 pineapple plants (30 plants × 15 plots) were screened for immature stages of Aedes mosquitoes weekly for 12 weeks. The required concentration (20 ppm) of novaluron was sprayed onto the selected pineapple plants (n = 1350) individually in 3 selected test sites for 5–10 s. The reduction in the vector population was interpreted as the percentage of reduction in immature stages of Aedes mosquitoes.ResultsThe 100% mortality of the Ae. aegypti larvae within 24 h was observed at 20 ppm (0.05 ml of novaluron 100 g/l in 250 ml of water) as the minimum dose. Variation in the number of Aedes larvae present in the control and intervention sites was found to be significantly different throughout the entire observational period (χ2 = 128.29, df = 11, P < 0.001). The total elimination of Aedes larvae continued for up to 2 weeks and a 50% reduction was observed until the 8th week.ConclusionsThe present study emphasizes that novaluron (10% EC) can be used as an effective larvicide at the treatment dose of 20 ppm. The residual effect of the IGR lasted for 12 weeks with a functional efficacy of 8 weeks. The 100% reduction of larval breeding was observed up to the 2nd week after application and the percentage reduction of immature stages remained > 50% until the 8th week. The lowest reduction (34.2%) was observed at 12 weeks after the initial treatment. Therefore, re-treatment may be recommended based on the reduction in the efficacy of the IGR.

Naturally Occurring Microbiota Associated with Mosquito Breeding Habitats and Potential Parasitic Species against Mosquito Larvae: A Study from Gampaha District, Sri Lanka.

A mosquito species has its own favourable requirements of abiotic and biotic characteristics including microbiota, in a breeding habitat. Some of the microbiota may cause parasitic or pathogenic effects to mosquito larvae such as species of viruses, parasitic bacteria, fungi, protists, entomopathogenic nematodes, and filamentous fungi. In Sri Lanka, there is a scarcity of information on microbiota associated with mosquito breeding habitats and their effect on mosquito larvae. Hence, the present study was conducted to determine microbiota species/taxa associated with a variety of mosquito breeding habitats in selected areas of the Gampaha District in Sri Lanka and the relationship, if any, the microbiota has with mosquito larva survival and breeding. Forty-five microbiota species belonging to 11 phyla were found from different mosquito breeding habitats with the highest percentage belonging to phylum Euglenozoa (27.89%). Species that belonged to the phylum Amoebozoa (1.22%) and Sarcodina (1.17%) had the lowest abundance, and each of its species richness was recorded as one. Philodina citrina followed by Monostyla bulla comprised 30.8% and 16.59%, respectively, of the total rotifer population. From the total microbiota, 25-50% existed as accidental while less than 25% rare, in the habitat type according to their abundance. Paddy fields had the highest species richness (17), evenness (23.52), Shannon-Weiner (66.64), and beta diversity (0.65) over 50% indicating high heterogeneity in microbiota composition among the habitats. Ciliated protists, namely, Vorticella microstoma, Zoothamnium spp., and Chilodinella sp., were identified as naturally occurring microbiota associated with Culex mosquito larvae that inhabited in paddy fields and associated irrigation canals. Only Vorticella microstoma caused a significant lethal effect on mosquito larvae. This study revealed that species of Cx. gelidus, Cx. pseudovishnui, Cx. tritaeniorhynchus, Cx. quinquefasciatus, and Cx. whitmorei served as hosts for V. microstoma where infectivity rate in Cx. tritaeniorhynchus reached 73.22. Chilodinella sp. selectively served as endoparasitic to Cx. gelidus larvae causing only 4.58% mortality, and invasive cysts of the pathogen were observed in the subcuticular layer of the host body. Even though Zoothamnium spp. were found on Cx. tritaeniorhynchus larvae, there was no lethal effect due to the attachment of the parasitic agent. The potential of these microbiotas in integrated vector controlling approaches in future perspectives is recommended.