Some characteristics of the larval breeding sites of Anopheles culicifacies species B and E in Sri Lanka

Background & objectives : Anopheles culicifacies Giles, the major malaria vector in Sri Lanka, existsas a species complex comprising two sympatric sibling species— species B and E. Species E is reportedto be the major vector of Plasmodium vivax and P. falciparum parasites in Sri Lanka, whilst speciesB is a poor or nonvector as in India. Knowledge of the breeding habits of the two sibling species canhelp in designing optimal vector control strategies. Hence, a survey was conducted in Sri Lanka tostudy the preferential breeding habitats of An. culicifacies species B and E.Methods: Immature forms of An. culicifacies were collected from identified breeding sites in malariousdistricts. Collected larvae were typed for their sibling species status based on mitotic Y-chromosomestructure. Data was analysed using Statistical Package for Social Science version 10.0.Results: An. culicifacies immature forms were found in 23 collection sites. Among these samples19 were found to have species E and four to have species B. All species B larvae were collected fromTonigala village in the Puttalam district. None of the 23 sites was found to have both species B and E.Species E, the major vector of malaria, appears to breed in variety of breeding sites which can be of anindication of its adaptive variation to exploit breeding sites with varying limnological characteristics.Interpretation & conclusion: The present findings have to be taken into account when formulatingmore effective larval control measures. They also show the need for a detailed study of possibledifferent preferences for larval breeding sites between species B and E

Studies on prevalence of anopheline species and community perception of malaria in Jaffna district, Sri Lanka

Background & objectives: Over two decades of civil unrest and the conflict situation have had detrimental effects on vector control activities and management of malaria in Jaffna district which is an endemic region for malaria in Sri Lanka. With the background that only a few small-scale studies on malaria and its vectors have been reported from this district, a study was designed to explore the current status of malaria in the Jaffna district in relation to vector and community aspects.Methods: Adults and larvae of anopheline mosquitoes were collected monthly from selected endemic localities. Species prevalence of the collected mosquitoes was studied while the collected adults of Anopheles subpictus, a potential vector in the district, was screened for sibling species composition based on morphological characteristics and exposed to common insecticides using WHO bioassay kits. Knowledge, attitude and practices (KAP) of the community were tested using a pre-tested structured questionnaire in high-risk and low-risk localities in the district.Results: The anopheline mosquito species distribution in the district was—An. culicifacies (0.5%), An. subpictus (46%), An. varuna (4%), An. nigerrimus (44%) and An. pallidus (5.5%). Among the collected larvae the percent prevalence of An. culicifacies was 13% and other species follows as: An. subpictus (71%), An. varuna (4%), An. nigerrimus (10%) and An. pallidus (2%). Sibling species B, C and D of An. subpictus were present in the district with the predominance of B in both coastal and inland areas, while all members showed both indoor and outdoor resting characteristics, they were highly resistant to DDT (4%) and highly susceptible to malathion (5%). KAP study in the district showed a reasonable level of knowledge, positive attitude and practices towards malaria.Conclusion: An. subpictus, the reported major vector of Jaffna and a well-established secondary vector of malaria in the country, continues to be the predominant anopheline species. The distribution of sibling species of An. subpictus complex in the Jaffna district, revealed for the first time, has implications for future studies on its bionomics and malaria transmission pattern in this area and the planning of control strategies for this region. The community perception of disease, which revealed a satisfactory knowledge indicates the potential for better community participation in future malaria control activities in this region. As potential vectors are still present, health authorities need to be vigilant to prevent any future epidemics of malaria

Variations in the adult ornamentation of anopheles (Cellia) Subpictus sibling species B in Eastern Sri Lanka

Anopheles (Cellia) subpictus Grasi sensu lato is a secondary vector of malaria in Sri Lanka and exists as a species complex comprising all four reported sibling species (species A, B, C and D). Significant variations in the ornamental pattern of wings and palpi were observed among specimens identified as sibling species B based on egg morphology. This led to categorization of species B into four distinct populations. This article reports the pattern variations and discusses the implications for classification of species B as the reported variations may conceal perfect identification of members of this complex

Impact of salinization and pollution of groundwater on the adaptation of mosquito vectors in the Jaffna peninsula, Sri Lanka

Mosquito-borne diseases are a major health concern in many tropical and sub-tropical countries. In the absence of specific treatment for many mosquito-borne diseases, vector control in the form of eliminating preimaginal development sites and insecticide application has an important role in controlling these diseases. Anthropogenic environmental changes have become important driving forces causing the adaptation of many major mosquito vectors to such changes. Anthropogenic activities are major contributors to global warming that is causing arise in sea levels. Sea level rise along with over exploitation of groundwater results in sea water intrusion to fresh water aquifers causing fresh water salinization in coastal zones. Human activities, including the extensive use of fertilizers and agrochemicals, also cause groundwater pollution. Mosquito vectors that normally lay eggs and undergo preimaginal development in fresh water are now seen to be adapting to develop in brackish and polluted water habitats. This article reviews recent findings that show the adaptation of mosquito vectors of human diseases to lay eggs and undergo preimaginal development in groundwater that is undergoing rapid salinization and pollution in the Jaffna peninsula.</span

Construction of Disjoint Virtual Backbones for Wireless Sensor Networks

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Impact of Fat Mass and Obesity Associated (FTO) Gene Variants and Lifestyle Factors on Obesity Traits in A Turkish Population

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