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

Global Climate Change and Its Potential Impact on Disease Transmission by Salinity-Tolerant Mosquito Vectors in Coastal Zones

Global climate change can potentially increase the transmission of mosquito vector-borne diseases such as malaria, lymphatic filariasis, and dengue in many parts of the world. These predictions are based on the effects of changing temperature, rainfall, and humidity on mosquito breeding and survival, the more rapid development of ingested pathogens in mosquitoes and the more frequent blood feeds at moderately higher ambient temperatures. An expansion of saline and brackish water bodies (water with <0.5 ppt or parts per thousand, 0.5–30 ppt and >30 ppt salt are termed fresh, brackish, and saline respectively) will also take place as a result of global warming causing a rise in sea levels in coastal zones. Its possible impact on the transmission of mosquito-borne diseases has, however, not been adequately appreciated. The relevant impacts of global climate change on the transmission of mosquito-borne diseases in coastal zones are discussed with reference to the Ross–McDonald equation and modeling studies. Evidence is presented to show that an expansion of brackish water bodies in coastal zones can increase the densities of salinity-tolerant mosquitoes like Anopheles sundaicus and Culex sitiens, and lead to the adaptation of fresh water mosquito vectors like Anopheles culicifacies, Anopheles stephensi, Aedes aegypti, and Aedes albopictus to salinity. Rising sea levels may therefore act synergistically with global climate change to increase the transmission of mosquito-borne diseases in coastal zones. Greater attention therefore needs to be devoted to monitoring disease incidence and preimaginal development of vector mosquitoes in artificial and natural coastal brackish/saline habitats. It is important that national and international health agencies are aware of the increased risk of mosquito-borne diseases in coastal zones and develop preventive and mitigating strategies. Application of appropriate counter measures can greatly reduce the potential for increased coastal transmission of mosquito-borne diseases consequent to climate change and a rise in sea levels. It is proposed that the Jaffna peninsula in Sri Lanka may be a useful case study for the impact of rising sea levels on mosquito vectors in tropical coasts

Salinity tolerance of wild Poecilia reticulata (guppy) under laboratory conditions

The present study was carried out to investigate the salinity tolerance of Poecilia reticulata (guppy) occurring in Sri Jayewardenepura canal system, in order to assess its suitability to control brackishwater breeding mosquito species such as Aedes sp. Guppies were exposed to different salinity levels directly and gradually under laboratory conditions in glass tanks. To test the direct effect of salinity, 9 different salinities (ranging from 0ppt as a control to35ppt) prepared in three replicates, each stocked with 10 fish were kept for a period of 12 weeks. To test the effect of gradual increase of salinity, three tanks containing freshwater were stocked with 10 fish in each and a gradual increase of salinity (by 5ppt once in 2 weeks up to 38ppt) was done. Mortality rates, growth (total length) and the breeding of fish were recorded in both experiments at regular time intervals. When the fish were exposed to different salinities directly, fish started dying at 10 ppt (10% mortality) after the fourth day of exposure and this mortality rate was observed in 10-20ppt salinity ranges within the 12 weeks (0% mortality was recorded in control tank).  50% survival was shown at 28ppt salinity level at the end of the 12 th week. Beyond 28ppt, there was 100% mortality. Fish showed an average of 5-7 mm growth in salinity levels up to 28ppt but they were not significantly different (p=0.886). Breeding was seen in salinity levels up to 20ppt producing 7-15 fry/female and the fry also could tolerate the salinity levels they were bred into with a mortality level of 20-30% within the study period. Contrast to the above results, the fish when exposed to gradual increasing of salinity levels could survive up to 38ppt with only a 20% mortality rate. They showed a length increase between 1-5mm, in all salinity levels but they were not significantly different (p=0.330). In gradually increasing salinity levels, fish were seen breeding even at 35 ppt (7-10 fry/female) with 10-20 % mortality rate. The results show that the guppy can tolerate and survive in salinity levels up to 28ppt when they are directly introduced from the wild and they can tolerate up to a level of 38ppt salinity if the salinity levels increase gradually. They can grow under saline conditions and breed successfully and the fry can survive well in the saline environment. This makes wild caught P. reticulata (guppy) a potential candidate that can be used as a bio-control agent in the control of species such as Aedes sp-mosquito that breed in brackish water environments of Sri Lanka.                                   KEYWORDS: Gappy,Salinity,Aedes sp,Bio-contro

Taxonomic review of Syzygium polypetalum (Wall.) Merr. & L.M. Perry (Myrtaceae) - a lesser known chasmophytic jambolan species of Assam

Syzygium polypetalum (Wall.) Merr. &amp; L.M. Perry, a lesser-known lithophytic and riparian jambolan species of north-eastern India, Bangladesh and Myanmar is reinvestigated with special reference to its taxonomic history, distributional range, habitat and morphology. An amplified description is presented here with colour photographs, illustrations and a distribution map

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

Detection of preimaginal forms of dengue vectors from environmental samples in Jaffna city, northern Sri Lanka: an eDNA-based approach

Vector surveillance is crucial for implementation of appropriate vector control strategies to reduce the transmission of vector-borne diseases such as dengue, a major public health concern in Sri Lanka. Aedes aegypti and Ae. albopictus are the primary and secondary vectors of dengue virus, respectively. Dengue is endemic in the Jaffna District and the presence of dengue vectors from many water bodies, including brackish water habitats, is reported. The use of environmental DNA (eDNA) has emerged as a novel tool to detect and identify vector species present in any aquatic environment. This study, used environmental DNA to determine the presence of major dengue vectors in different aquatic habitats in the Municipal limits of the Jaffna District. Potential pre-imaginal developmental sites of dengue vectors were identified in randomly selected 10 blocks consisting of at least 40 houses within the study location. One hundred and twenty water samples without any visible preimaginal forms were collected from these sites to extract eDNA. PCR assays were performed using species-specific primers designed for Ae. aegypti and Ae. albopictus. The presence of Ae. aegypti and Ae. albopictus was identified in 12 (10.0%) and 30 samples (25.0%), respectively. The presence of both species was detected in nine samples (7.5%). The salinity of the water from which Aedes DNA was detected ranged from 0–7 gL-1. The results revealed that eDNA is an indirect but valid surveillance tool for monitoring preimaginal developmental forms of mosquitos in the aquatic environment

Automatic detection of accommodation steps as an indicator of knowledge maturing

Jointly working on shared digital artifacts – such as wikis – is a well-tried method of developing knowledge collectively within a group or organization. Our assumption is that such knowledge maturing is an accommodation process that can be measured by taking the writing process itself into account. This paper describes the development of a tool that detects accommodation automatically with the help of machine learning algorithms. We applied a software framework for task detection to the automatic identification of accommodation processes within a wiki. To set up the learning algorithms and test its performance, we conducted an empirical study, in which participants had to contribute to a wiki and, at the same time, identify their own tasks. Two domain experts evaluated the participants’ micro-tasks with regard to accommodation. We then applied an ontology-based task detection approach that identified accommodation with a rate of 79.12%. The potential use of our tool for measuring knowledge maturing online is discussed

Fisheries Sciences

The history of fisheries research in India goes back to the early 19th century, when dried or preserved material was sent to the Museums of Natural History in England and other European countries for identification and cataloguing (Silas, 2003). Some of the earliest scientific observations on fisheries in pre-independent India were the works of Francis Hamilton-Buchanan (1822) and Francis Day, whose initial work on ‘The Fishes of Malabar’ (1865), was followed by a monograph on ‘The Fishes of India’ (1875-78); and two more volumes on ‘Fishes’ in ‘The Fauna of British India, including Ceylon and Burma’ (1889). The enactment of Indian Fisheries Act of 1897 was a major landmark in the development of fisheries in pre-independent India. In the latter half of 19th century, emphasis on coastal and deep-water surveys in the Bay of Bengal and Andaman Sea led to possession of valuable information on new deepwater fauna of fishes and crustaceans, hydrology and plankton. The initial work by the Zoological Survey of India on fisheries and marine biology through eminent leadership of its Directors, viz. Nelsen Annandale, Stanley Kemp, Seymour Sewell, Baini Prasad and S. L. Hora during first half of the 20th century led to generation of several first hand information on the taxonomy, bionomics, eco-biology, hydrology, and fish and fisheries of upland lakes, rivers and coastal waters. The emphasis shifted from coastal and deep-water surveys in the Bay of Bengal and Andaman Sea to upland lakes, rivers and coastal waters in the beginning of the 20th century. With the establishment of the Bureau of Fisheries in 1907, the Madras Presidency became the pioneer for fisheries development in India. Establishment of the Marine Biological Station at Krusadai Island in 1924 and subsequently at West Hill and Ennore led to organized research programmes on pearl and chank fisheries in the Gulf of Mannar