Biodiversity of mosquitoes (Diptera: Culicidae) in phytotelmata from Car Nicobar Island, India.

The Culicidae mosquito family breeds in various natural and artificial water bodies. Phytotelmata are plant structures that hold water and are used by many mosquito species during their life cycle. Mosquitoes are disease vectors, and phytotelmata play an important role in harbouring them. Investigating these phytotelmata will facilitate to develop appropriate site specific vector control strategy. Approximately 750 phytotelmata in 16 locations on Car Nicobar Island was examined. Mosquito larvae were collected from different habitats such as tree holes, root holes, leaf axils, and bamboo stumps. On average, the number of larvae per 10 ml of water ranged from 0.003 to 3.833. Among the 16 mosquito species identified, there were vectors of malaria (Anopheles sundaicus), dengue (Aedes aegypti and Aedes albopictus) and filariasis (Culex quinquefasciatus), belonging to seven genera. The most common phytotelmata were coconut trees (17.5%) followed by Java apple trees (10.3%) and bamboo stumps (7.1%). The most widespread mosquito species was Aedes edwardsi, followed by Aedes malayensis and Ae. albopictus, and the per cent of phytotelmata that contained these species were 42.6, 22.0, and 16.8% respectively. Anopheles mosquitoes had the highest container index (6.1%) in root holes, while Aedes and Culex mosquitoes were more frequently found in bamboo stumps. The alpha biodiversity indices indicated that the mosquito population in Car Nicobar Island was highly diverse (S = 16; DMg = 36.9). Tree holes showed the highest diversity, as all 16 species were collected from them. Assessment of phytotelmata, there is a significant relationship observed between mosquito genus, village, habitat, and tree families, on the remote island of Car Nicobar. Considering the presence of disease-transmitting mosquito vectors in the phytotelmata, these habitats should be considered when implementing control measures to eliminate mosquito-borne infections.

Characterization of the anopheline vector breeding habitats: Implications for elimination of malaria in tribal inhabited Car Nicobar Island.

Background & objectives: Malaria is an important public health problem in Andaman & Nicobar archipelago. Among the three districts, Nicobar is the most endemic district where API is >2. In this district, the malaria incidence in Car Nicobar Tehsil has declined steadily over the past 10 years. A renewed initiative to consolidate this gain is being made with the ultimate objective of achieving zero indigenous transmission of malaria in Car Nicobar. So, the present study undertook a close environmental monitoring of water bodies for assessing changes in the risk potential of mosquito vector breeding habitats which can augment the elimination programme. Methods: The breeding habitats of anopheline mosquitoes were sampled in 16 areas of Car Nicobar Island for eight time periods during 2017-2020. Along with anophelines, various associated water parameters (n=60) were estimated, viz. physicochemical (n=13), and biological, which included culicine mosquito immatures, insect predators (n=5), phytoplanktons (n=31) and zooplanktons (n=10). Results: In the 16 study sites, overall 1126 surface water stagnating bodies constituting 21 different habitat types were surveyed. Of these, 17 were positive for anopheline breeding. Water bodies from three villages were consistently found to be positive for anopheline breeding. However, early instars of anopheline larvae were more abundant compared to the late instars. Four anopheline species were recorded, including Anopheles sundaicus, A. barbirostris, A. insulaeflorum and A. subpictus, in which 48 per cent were A. sundaicus. Multivariable analysis indicated that anopheline density was significantly higher in permanent water bodies than in temporary habitats (P<0.05) (high risk of anophelines). The highest pH (≥8.2), dissolved solids (≥0.39) levels showed significantly (P<0.05) decreased larval densities (lower risk of breeding), adjusted with breeding sites and season. Nitrite levels increased (P=0.022) larval densities. Interpretation & conclusions: The present study facilitated estimating the productive period of a larval habitat enabling target larval sources to reduce adult populations. Implementing larviciding strategy before monsoon season is presumably the most cost-effective strategy. The output can be utilized for environmental monitoring of mosquito breeding risk in other malaria endemic areas, particularly where medium/large water bodies are the predominant breeding sites for malaria vectors.

Diversity of native larvivorous fish fauna during pre- and post-tsunami in Car Nicobar, Andaman & Nicobar Islands, India.

BACKGROUND & OBJECTIVES: Malaria is a serious public health problem in Car Nicobar Island, Andaman & Nicobar Islands, India. Using larvivorous fishes has proved to be the cheapest method for vector management approach, with long suppression of mosquito population. This study aims to scale-up the diversity of larvivorous fishes and their potential larvivoracity to evolve an appropriate biological intervention strategy against the immature stages of malaria vectors. METHODS: During 2003 (pre-tsunami) and 2014-2016 (post-tsunami), an ecological descriptive survey was carried out in the water bodies around Car Nicobar Island. Fishes were captured using fishing nets and cast nets; and placed in plastic jars and preserved in formalin solution. Fishes were identified and classified according to the available keys. Their abundance and data on the current conservation status was recorded and analyzed. Their potential larvivoracity was graded according to their feeding intensity. RESULTS: Pre-tsunami, a total of 27 larvivorous fish species belonging to 11 orders, 23 families and 23 genera were identified. Order Perciformes and the family Cyprinidae were the most ascendant group constituting 51.9 and 11.1%, respectively. While, 80.8% of species were preferred to inhabit the freshwater region, only 37% of species were surface feeders (SF). According to the conservation, assessment and management plan (CAMP, 1998), 44.4% species were at lower risk least concern (LRlc), while 55.6% species were at least concerned (LC) as per the IUCN, 2017 categorization. However, after the tsunami, 17 fish species had gone extinct and 10 fish species were found to remain alive in the local water bodies. INTERPRETATION & CONCLUSION: Post-tsunami, the larvivoracity analysis indicated that Ophiocara aporos, Ophiocara procephala, Valamugil seheli, Channa punctata, Kuhlia rupestris, Khulia mugil, and Terapon jarbua possess high-level larvivorous potentiality in nature and are recommended for vector control in the study area. These fish species were facing several anthropogenic threats, such as human interference, loss of habitat, trade, overexploitation, and fishing. Therefore, it is important to protect the water bodies from external impact and implement the conservation strategies. Further, periodic fish fauna surveys, identification of breeding sites, scale-up of the larvivorous potentiality at the field level, creating public awareness through health education on establishment of larvivorous fish ponds and planning for mass rearing of the native fish species should be adopted as part of vector management approach in the endemic malarious region of Car Nicobar Island.

GC/MS profiling, in vitro anti-leptospiral and haemolytic activities of Boesenbergia rotunda (L.) Mansf. used as a medicinal plant by Nicobarese of Andaman and Nicobar Islands.

Leaves of the plant Boesenbergia rotunda are used by the Nicobarese tribe of Andaman and Nicobar Islands, India, to prepare traditional medicine for treating fever, headache and body ache. In the present investigation, methanol fraction of these leaves were analysed by GC/MS that revealed the presence of 25 compounds. The anti-leptospiral activity of methanol crude extract was determined by both microdilution and macrodilution methods. The MICs of the extract were tested against 24 pathogenic leptospiral strains and ranged between 62.5-125 µg/mL in both microdilution and macrodilution. The range of MBCs was 250 and 500 µg/mL in macrodilution and microdilution respectively. The crude extract was subjected to cytotoxic studies and found to have negligible or no haemolytic activity, exhibiting IC50 values of greater than 4 mg/mL. Further in vivo studies are needed to investigate the pharmacological and toxicological properties of Boesenbergia rotunda, before it can be considered as a new anti-leptospiral agent.

Ethno medicine and healthcare practices among Nicobarese of Car Nicobar - an indigenous tribe of Andaman and Nicobar Islands.

ETHNOPHARMACOLOGICAL RELEVANCE: This study is an attempt to document the use of medicinal plants by Nicobarese tribe from the Car Nicobar Island of Andaman and Nicobar Islands. Inspite of the availability of modern healthcare facilities tribal people often take herbal medicines and Traditional Knowledge Practitioners (TKPs) serve as the local medical experts in Car Nicobar Island. AIM OF THE STUDY: The present study was to conduct an ethnomedicinal survey among the TKPs of Nicobarese tribe of the inhabitants of Car Nicobar Island, Andaman and Nicobar Islands, India. MATERIALS AND METHODS: Field research was conducted in 15 villages of Car Nicobar Island during March 2011-February 2012. TKPs were interviewed with a questionnaire-guided ethnomedical survey protocol. The data obtained were quantitatively analysed using the informant consensus factor (ICF) and use value (UV). Voucher specimens of all cited plants were collected and deposited at Regional Medical Research Centre (ICMR), Port Blair. RESULTS: Use of 150 medicinal plant species, belonging to 122 genera encompassing 59 families were recorded during the survey. These 150 species are employed to treat 47 different medicinal uses, divided into nine categories of use. The highest ICF (0.68) was obtained for the gastrointestinal system. The Euphorbiaceae family exhibited the highest number of citations, and the species with the highest UVs were Morinda citrifolia L., Tabernaemontana crispa Roxb. and Colubrina asiatica (L.) Brongn. Of the medicinal plants reported, the most common growth form was shrubs (28%). Among several parts of individual plant species which are used, leaves constitute the major portion in preparation of medicines. Remedies were generally prepared using water as the excipient. CONCLUSIONS: This study is an attempt to document the use of medicinal plants from the Car Nicobar Island of the Andaman and Nicobar Islands. Future phytochemical and pharmacological studies are needed to confirm the efficacy and safety of the identified plants.