The final article in a series of three publications examining the global distribution of 41 dominant vector species (DVS) of malaria is presented here. The first publication examined the DVS from the Americas, with the second covering those species present in Africa, Europe and the Middle East. Here we discuss the 19 DVS of the Asian-Pacific region. This region experiences a high diversity of vector species, many occurring sympatrically, which, combined with the occurrence of a high number of species complexes and suspected species complexes, and behavioural plasticity of many of these major vectors, adds a level of entomological complexity not comparable elsewhere globally. To try and untangle the intricacy of the vectors of this region and to increase the effectiveness of vector control interventions, an understanding of the contemporary distribution of each species, combined with a synthesis of the current knowledge of their behaviour and ecology is needed. Expert opinion (EO) range maps, created with the most up-to-date expert knowledge of each DVS distribution, were combined with a contemporary database of occurrence data and a suite of open access, environmental and climatic variables. Using the Boosted Regression Tree (BRT) modelling method, distribution maps of each DVS were produced. The occurrence data were abstracted from the formal, published literature, plus other relevant sources, resulting in the collation of DVS occurrence at 10116 locations across 31 countries, of which 8853 were successfully geo-referenced and 7430 were resolved to spatial areas that could be included in the BRT model. A detailed summary of the information on the bionomics of each species and species complex is also presented. This article concludes a project aimed to establish the contemporary global distribution of the DVS of malaria. The three articles produced are intended as a detailed reference for scientists continuing research into the aspects of taxonomy, biology and ecology relevant to species-specific vector control. This research is particularly relevant to help unravel the complicated taxonomic status, ecology and epidemiology of the vectors of the Asia-Pacific region. All the occurrence data, predictive maps and EO-shape files generated during the production of these publications will be made available in the public domain. We hope that this will encourage data sharing to improve future iterations of the distribution maps.

ABSTRACT: BACKGROUND: The Anopheles dirus complex includes efficient malaria vectors of the Asian forested zone. Studies suggest ecological and biological differences between the species of the complex but variations within species suggest possible environmental influences. Behavioural variation might determine vector capacity and adaptation to changing environment. It is thus necessary to clarify the species distributions and the influences of environment on behavioural heterogeneity. METHODS: A literature review highlights variation between species, influences of environmental drivers, and consequences on vector status and control. The localisation of collection sites from the literature and from a recent project (MALVECASIA) produces detailed species distributions maps. These facilitate species identification and analysis of environmental influences. RESULTS: The maps give a good overview of species distributions. If species status partly explains behavioural heterogeneity, occurrence and vectorial status, some environmental drivers have at least the same importance. Those include rainfall, temperature, humidity, shade, soil type, water chemistry and moon phase. Most factors are probably constantly favourable in forest. Biological specificities, behaviour and high human-vector contact in the forest can explain the association of this complex with high malaria prevalence, multi-drug resistant Plasmodium falciparum and partial control failure of forest malaria in Southeast Asia. CONCLUSIONS: Environmental and human factors seem better than species specificities at explaining behavioural heterogeneity. Although forest seems essential for mosquito survival, adaptations to orchards and wells have been recorded. Understanding the relationship between landscape components and mosquito population is a priority in foreseeing the influence of land-cover changes on malaria occurrence and in shaping control strategies for the future.

Among Oriental anopheline mosquitoes (Diptera: Culicidae), several major vectors of forest malaria belong to the group of Anopheles (Cellia) leucosphyrus Dönitz. We have morphologically examined representative material (> 8000 specimens from seven countries) for taxonomic revision of the Leucosphyrus Group. Six new species are here described from adult, pupal and larval stages (with illustrations of immature stages) and formally named as follows: An. latens n. sp.(= An. leucosphyrus species A of Baimai et al., 1988b), An. cracens n. sp., An. scanloni n. sp., An. baimaii n. sp.(formerly An. dirus species B, C, D, respectively), An. mirans n. sp. and An. recens n. sp. Additionally, An. elegans (James) is redescribed and placed in the complex of An. dirus Peyton & Harrison (comprising An. baimaii, An. cracens, An. dirus, An. elegans, An. nemophilous Peyton and Ramalingam, An. scanloni and An. takasagoensis Morishita) of the Leucosphyrus Subgroup, together with An. baisasi Colless and the An. leucosphyrus complex (comprising An. balabacensis Baisas, An. introlatus Baisas, An. latens and An. leucosphyrus). Hence, the former Elegans Subgroup is renamed the Hackeri Subgroup (comprising An. hackeri Edwards, An. pujutensis Colless, An. recens and An. sulawesi Waktoedi). Distribution data and bionomics of the newly defined species are given, based on new material and published records, with discussion of morphological characters for species distinction and implications for ecology and vector roles of such species. Now these and other members of the Leucosphyrus Group are identifiable, it should be possible to clarify the medical importance and distribution of each species. Those already regarded as vectors of human malaria are: An. baimaii[Bangladesh, China (Yunnan), India (Andamans, Assam, Meghalaya, West Bengal), Myanmar, Thailand]; An. latens[Borneo (where it also transmits Bancroftian filariasis), peninsular Malaysia, Thailand]; probably An. cracens (Sumatra, peninsular Malaysia, Thailand); presumably An. scanloni (Thailand); perhaps An. elegans (the Western Ghat form of An. dirus, restricted to peninsular India); but apparently not An. recens (Sumatra) nor An. mirans[Sri Lanka and south-west India (Karnataka, Kerala, Tamil Nadu)], which is a natural vector of simian malarias. Together with typical An. balabacensis, An. dirus and An. leucosphyrus, therefore, the Leucosphyrus Group includes about seven important vectors of forest malaria, plus at least a dozen species of no known medical importance, with differential specific distributions collectively spanning > 5000 km from India to the Philippines.

Mosquitoes (Diptera: Culicidae) of the Anopheles (Cellia) Myzomyia Series are important malaria vectors in Africa, India and Southeast Asia. Among 10 named species of Myzomyia known from the Oriental Region, seven form the An. minimus group. Even for expert taxonomists, the adults of these species remain difficult to identify morphologically. For technical staff of malaria control programmes, confusion may extend to misidentification of species that are not formally within the minimus group. For identification of specimens from Indochina (Cambodia, Laos, Vietnam), we describe a multiplex polymerase chain reaction (PCR) assay, based on rDNA internal transcribed spacer 2 (ITS2) sequences, that employs a cocktail of primers to identify An. minimus Theobald sibling species A and C (sensu; Green et al., 1990) and three other species in the An. minimus group (An. aconitus Dönitz, An. pampanai Büttiker & Beales, An. varuna Iyengar), as well as An. jeyporiensis James, also belonging to the Myzomyia Series. As the test is DNA-based, it can be applied to all life stages of these mosquitoes for ecological investigations and vector incrimination studies. This PCR assay is simpler, quicker, cheaper and more readily interpreted than previous assays.

Effective control of Anopheles minimus s.l., an important malaria vector in Southeast Asia, is based on the accurate identification of species within An. minimus complex, which cannot be distinguished using morphological characters. Derived from individual random amplified polymorphic DNA markers, sequence characterized amplified regions were analysed for the design of species-specific paired-primers. Combination of these primers resulted in the development of a simple, robust multiplex PCR able to identify both species An. minimus A and C belonging to the complex, hybrids AC, and three sympatric and closely related species, An. aconitus, An. pampanai and An. varuna. Hybrids AC do not possess alleles of both parents but exhibit novel adaptive potentials resulting from recombination among parental genes leading to hybrizyme.

Studies on biting behaviour and biting cycles of medically important mosquitoes were carried out in Madhupur village and Tarajan tea estate of upper Assam. Collections were made off human baits outdoors and indoors and off cattle bait outdoors from August 1991 to July 1992. Human bait collections were performed using the 'stationary direct bait' technique. A total of 9,072 adult host seeking female mosquitoes representing 26 species and 5 genera were collected off baits of which 36.9% were collected off human baits and the rest from cattle. All mosquitoes were primarily zoophilic, although significant numbers were collected biting man outdoors. Biting preferences of important Japanese encephalitis (JE) vectors for man and cattle were studied using outdoor man:outdoor cattle ratio (attraction ratio = AR). Culex quinquefasciatus was attracted towards human baits the most (AR = 8.1:1), followed by Cx. bitaeniorhynchus (AR = 1.6:1) and Mansonia annulifera (AR = 1.3.1). The hourly biting activity of important JE vectors throughout the night on two bait types was also studied using three point moving averages. Hierarchical agglomerative cluster analysis was used to compare and classify mosquitoes on the basis of their similarity in biting rhythms.

Tea industry is a labor intensive agro-industry and filariasis is mostly localized among the tea garden workers in Assam. The workers live inside the gardens in colonies. Studies conducted in two cosecutive years revealed that among the host seeking Culex quinquefasciatus average infection rate was 4.6% and with 2.1 larvae per mosquito. The overall prevalence of infective mosquitos was 0.8% with average L3 load of 2.0 per mosquito. The probability of infected mosquitos surviving to have complete development of filarial larvae (13 days) was 0.17. The expectation of infective life was 1.416 days for man biting Cx. quinquefasciatus and the estimated adult survival rate of was 87.6%. It has been estimated that a total of 22,569 mosquito bites were received/man/year in tea garden environment out of which 182 bites/man/year were infective (0.806%). The monthly biting rate varied from 310-4,758.5 bites per man (mean 1,846 +/- 1,389.7 SD). Monthly transmission index of W. bancrofti filaria showed two periods of transmission. In both the year no infection was detected during February and March and infection rate remained low up to May (average infection in April 0.72% and in May 0.48%).

Temporal changes in the biting density and host-seeking periodicity of Culex quinquefasciatus, the vector of bancroftian filariasis, were studied for two years in the tea agro-ecosystem of Assam, India. Average biting density of the vector varied from 0.8/hour in December to 13.3/hour in March. Minimum temperature was found to have a limiting effect on the biting density of the vector mosquitos. Multiple regression analysis showed that the rainfall and minimum temperature were significant factors influencing biting density of this vector mosquito. The biting rhythm of Cx. quinquefasciatus was found to be nocturnal with two distinct peak periods of biting activity. The first peak was around 19.00 to 20.00 hours and the second peak period was around 22.00 to 23.00 hours. Biting activity however was seen throughout the night with declining trend as the night proceeded.

Temporal changes in the abundance of host-seeking, potential Japanese encephalitis (JE) vector mosquitos and the role of some ecological factors that are modulating the abundance of vector mosquitos were studied. Vector surveillance was conducted for one year in 4 JE prone villages of Dibrugarh, Assam. Among potential JE vectors, the most abundant mosquito was Culex vishnui s.s. comprising about 22.32%. Maximum density of the mosquito was found during the month of April and another peak was observed in the month of September. The influence of meteorological factors on the abundance of JE vectors was found to vary from species to species. The final multiple regression equations (after variables were selected using STEPWISE procedure) consisted of a combination of linear, quadratic, cubic and interactive ecological variables and accounted for 25-98% of the variations in the abundance of JE vector mosquitos. Complex interactions among environmental factors, such as minimum and maximum temperature, rainfall and flood level are involved in modulating the seasonal abundance of mosquitos. A time lag is involved before a cause and effect relationship is established between environmental parameters (independent variables) and entomological variables (dependent variables). Inundation caused by flooding is favorable for mansonioid mosquito species whereas it has an adverse effect on non-mansonioid mosquito species.

SUMMARYA temporal relationship of Japanese encephalitis virus (JEV) transmission in pigs, mosquitoes and humans revealed that sentinel pig seroconversions were significantly associated with human cases 4 weeks before (P=0·04) their occurrence, highly correlated during the same time and 2 weeks before case occurrence (P<0·001), and remained significantly correlated up to 2 weeks after human case occurrence (P<0·01). JEV was detected in the same month in pigs and mosquitoes, and peaks of pig seroconversion were preceded by 1-2 months of peaks of infection in vectors. Kaplan-Meier analysis indicated that detection of JEV-positive mosquitoes was significantly associated with the median time to occurrence of seroconversion in pigs (P<0·05). This study will not only help in predicting JEV activity but also accelerate timely vector control measures and vaccination programmes for pigs and humans to reduce the Japanese encephalitis risk in endemic areas.

A study was conducted to evaluate the preventive efficacy of insecticide-treated mosquito nets (ITMNs) and mosquito repellent (MR) in a malaria-endemic foothill area of Assam, India, with forest ecosystem. During the first year, a survey was conducted in four demarcated sectors (A-D) to observe the malaria endemicity and vector prevalence patterns before implementing intervention measures. All four sectors were endemic for malaria. The prevalence of established malaria vectors such as Anopheles dirus, A. minimus and A. philippinensis was observed. During the second year, intervention measures were implemented in the four sectors as follows: A, ITMN + MR; B, ITMN; C, MR; D, no intervention. The most effective intervention was in sector A, followed by sectors B and C. Sectors A and B exhibited significantly higher (P < 0.001) malaria protective efficacy during both the first and second years of intervention compared with sector D. The total vector population in the three intervention sectors decreased significantly compared with that of the non-intervention one. Information-education-communication activities motivated the residents to participate actively in the intervention programme. The finding could be an effective model for containment of high malaria morbidity in inaccessible forest fringe areas of the northeastern region of India.

During June-September 2008, an illness characterized by fever, headache and joint pain was reported in Assam state, northeast India. It presented characteristic features resembling chikungunya or dengue virus infection based on clinical symptoms. Dengue and chikungunya IgM antibody was detected in 10.0%(28/280) and 3.6%(10/280) patients respectively. The chikungunya positive patients did not travel to and from any endemic region confirming indigenous transmission. Persistent arthralgia and hearing loss has been observed in a recovered patient. Entomological surveys revealed the presence of vectors viz. Aedes aegypti and Aedes albopictus. This is the maiden report of chikungunya occurrence in Northeast India.

Entomological surveys were conducted for three consecutive years in core and buffer zone of the Dibru-Saikhowa biosphere reserve in pre monsoon, monsoon and post-monsoon seasons. A total of 52 species of mosquitoes under eleven genera have been detected. The genus Anopheles (18 species) was the predominant followed by Culex, Aedes, Mansonia, Armigeres, Mimomyia, Ochlerostatus, Malaya, Toxorhynchites, Ficalbia and Aedeomyia. The buffer zone of the forest reserve where human habitations are there exhibited the presence of maximum number of species (49 species under 10 genera) in comparison to core zone (42 species under 10 genera). In buffer zone, maximum numbers of species (38) were recorded in monsoon season followed by post- monsoon (35 species) and Pre-monsoon season (34 species). Whereas in core zone, maximum number of species were collected in post monsoon season followed by pre monsoon season and monsoon season. In Core and buffer zone, the maximum species were recorded from the ground pool habitat and slow flowing stream respectively. Among the disease vectors, the potential Japanese encephalitis vectors incriminated in India were very much prevalent. This study provides the list of available mosquito species recorded for the first time in the Dibru-Saikhowa biosphere reserve.

A mosquito faunistic survey conducted during 1999-2005 in 7 different states of the northeastern (NE) region of India revealed that the region is very rich in mosquito fauna, particularly of the genus Aedes. From the present survey and earlier published reports, a total of 48 species of Aedes and a related genus Verrallina were recorded. The state of Assam contributed the highest number of species compared to the other 6 states, namely Arunachal Pradesh, Manipur, Meghalaya, Mizoram, Nagaland, and Tripura. Larvae of 46 species were collected from 16 different habitats and for some species the habitats were species specific. The known dengue vectors, Aedes aegypti and Ae. albopictus, were recorded from all 7 states, although Ae. aegypti was not known earlier from Mizoram, Nagaland, and Tripura states. Aedes albotaeniatus was a new addition to the Aedes fauna of the region.

The northeast region of India is one of the world's most significant biodiversity hotspots. One of the richest bird areas in India, it is an important route for migratory birds and home to many endemic bird species. This paper describes a literature-based dataset of species occurrences of birds of northeast India. The occurrence records documented in the dataset are distributed across eleven states of India, viz.: Arunachal Pradesh, Assam, Bihar, Manipur, Meghalaya, Mizoram, Nagaland, Sikkim, Tripura, Uttar Pradesh and West Bengal. The geospatial scope of the dataset represents 24 to 29 degree North latitude and 78 to 94 degree East longitude, and it comprises over 2400 occurrence records. These records have been collated from scholarly literature published between1915 and 2008, especially from the Journal of the Bombay Natural History Society (JBNHS). The temporal scale of the dataset represents bird observations recorded between 1909 and 2007. The dataset has been developed by employing MS Excel. The key elements in the database are scientific name, taxonomic classification, temporal and geospatial details including geo-coordinate precision, data collector, basis of record and primary source of the data record. The temporal and geospatial quality of more than 50% of the data records has been enhanced retrospectively. Where possible, data records are annotated with geospatial coordinate precision to the nearest minute. This dataset is being constantly updated with the addition of new data records, and quality enhancement of documented occurrences. The dataset can be used in species distribution and niche modeling studies. It is planned to expand the scope of the dataset to collate bird species occurrences across the Indian peninsula.

BELARUS IS SITUATED AT A CROSSROAD OF NATURAL BORDERS OF SPECIES DISTRIBUTIONS: the NE part is situated in a taiga zone, whereas the other part of terrain is in the European forest zone. The distance of Belarus to the steppe zone is about 330 kilometers. This geographical position and the extensive knowledge of its fauna can be used to monitor changes in the distribution of different species. An intensive study of open habitat ground beetles was carried out from 1975-2008 in Belarus, using pitfall traps, quadrate-sampling methods, hand collecting, netting and light traps. In total, more than 130 000 specimens of ground beetles belonging to 169 species were collected from 62 fields and 11 meadows of different types. 217 specimens of Calosoma investigator (Illiger 1798), 2 specimens of Calosoma denticolle (Gebler 1833), and one specimen of Harpalus subcylindricus (Dejean, 1829), Harpalus honestus (Duftschmid 1812) and Zabrus tenebrioides (Goeze 1777) were present in this material. All specimens were macropterous and exclusively caught at fields and waste grounds on sandy soil. Nowadays Belarus is the northernmost location for these species in Eastern Europe. Steppe species most probably migrated to SE Belarus from NE Ukraine, using Dnieper and its river valleys. The shift in the geographic distribution of steppe species during the last thirty years in Belarus have been attributed to a higher frequency of warmer and wetter summers in the last few decades.

We studied the prevalence of avian Plasmodium in 509 mosquitoes of 9 species collected from the Ishigaki and Iriomote islands in the Yaeyama Archipelago, located southwest from the mainland of Japan. Two identical avian Plasmodium lineages were detected from Culex (Culiciomyia) nigropunctatus. Detected lineages were phylogenetically classified into different clade to avian Plasmodium lineages from birds and mosquitoes in the mainland of Japan but identical to a lineage detected from a resident bird, White-breasted Waterken (Amaurornis phoenicurus). This is the first detection of avian Plasmodium DNA from mosquitoes in the Yaeyama Archipelago and suggested that resident birds might have been infected with an avian Plasmodium lineage specific to the studied area and C. nigropunctatus could be the candidate vector mosquito species.

A study was conducted to evaluate the preventive efficacy of insecticide-treated mosquito nets (ITMNs) and mosquito repellent (MR) in a malaria-endemic foothill area of Assam, India, with forest ecosystem. During the first year, a survey was conducted in four demarcated sectors (A-D) to observe the malaria endemicity and vector prevalence patterns before implementing intervention measures. All four sectors were endemic for malaria. The prevalence of established malaria vectors such as Anopheles dirus, A. minimus and A. philippinensis was observed. During the second year, intervention measures were implemented in the four sectors as follows: A, ITMN + MR; B, ITMN; C, MR; D, no intervention. The most effective intervention was in sector A, followed by sectors B and C. Sectors A and B exhibited significantly higher (P < 0.001) malaria protective efficacy during both the first and second years of intervention compared with sector D. The total vector population in the three intervention sectors decreased significantly compared with that of the non-intervention one. Information-education-communication activities motivated the residents to participate actively in the intervention programme. The finding could be an effective model for containment of high malaria morbidity in inaccessible forest fringe areas of the northeastern region of India.

Larvae of Ayurakitia peytoni were collected in July 2008 from Pandanus axils during a survey of mosquito fauna in Meghalaya. This is the 1st record of the genus Ayurakitia in India, extending the known distribution of this genus farther west.

Entomological surveys were conducted for three consecutive years in core and buffer zone of the Dibru-Saikhowa biosphere reserve in pre monsoon, monsoon and post-monsoon seasons. A total of 52 species of mosquitoes under eleven genera have been detected. The genus Anopheles (18 species) was the predominant followed by Culex, Aedes, Mansonia, Armigeres, Mimomyia, Ochlerostatus, Malaya, Toxorhynchites, Ficalbia and Aedeomyia. The buffer zone of the forest reserve where human habitations are there exhibited the presence of maximum number of species (49 species under 10 genera) in comparison to core zone (42 species under 10 genera). In buffer zone, maximum numbers of species (38) were recorded in monsoon season followed by post- monsoon (35 species) and Pre-monsoon season (34 species). Whereas in core zone, maximum number of species were collected in post monsoon season followed by pre monsoon season and monsoon season. In Core and buffer zone, the maximum species were recorded from the ground pool habitat and slow flowing stream respectively. Among the disease vectors, the potential Japanese encephalitis vectors incriminated in India were very much prevalent. This study provides the list of available mosquito species recorded for the first time in the Dibru-Saikhowa biosphere reserve.

The effect of insecticide-treated mosquito nets (ITMNs) on Japanese Encephalitis (JE) virus seroconversion in pigs and humans was studied in Assam, Northeast India. A sharp reduction of seroconversion rate in human and pig was found in treated localities after intervention. A marked reduction was achieved in humans (risk ratio [RR]= 0.28, 95% confidence interval [CI]= 0.16-0.49) and pigs (RR = 0.21, CI = 0.11-0.40) in the Kollolua locality where ITMNs were used on both humans and pigs compared with the other two area, Athabari and Rajmai, where ITMNs were covering only either humans or pigs. Monitoring of the mosquito population in and around cattle sheds during dusk revealed no significant decline (P > 0.05) of vector density during the post-intervention period in study localities. In spite of the high preponderance of potential JE vector outdoors during the post-intervention period, an encouraging line of defense against circulation of JE virus through the use of ITMNs can be achieved in endemic areas.

Entomological survey was conducted to know the breeding habitat preference of the forest breeder malaria vector Anopheles baimaii, known earlier as An. dirus species D in the northeastern region of India. Breeding potential of the vector in forest areas was found to be high in water stored in jungle pool (69.84%) followed by elephant footprints with clear water (39.13%) and with turbid water (26.19%), whereas in forest fringe areas, the vector breeding was more prominent in elephant footprints: 65.11% in clear water and 62.5% in turbid water. Although other habitats had shown only low breeding of the vector, all types of habitats were positively correlated with malaria occurrence. Cattle hoof marks (r = 0.998) and elephant footprint (turbid; r = 0.999) explained nearly the same amount of variance. It was observed that deforestation as well as elephant habitat-type destruction had engendered man-elephant conflicts intensively in fringe areas. Seasonal abundance pattern of this vector was found to vary in forest and forest fringe areas in relation to different habitats. Seasonal abundance of An. baimaii was significantly different in different habitats. The Tukey post hoc comparisons indicated that the abundance of An. baimaii in different habitats was significantly higher (P < 0.05) in monsoon season than that of premonsoon and postmonsoon seasons. No significant difference was observed between premonsoon and postmonsoon seasons. The findings therefore will eventually help to predict transmission of malaria in targeted area and in formulating an improved malaria control program in the northeastern region of India.

The occurrence and abundance of darwinulid ostracods, as well as environmental factors influencing these patterns, were investigated in the alluvial valley of the upper Paraná River. Ostracods were sampled from several substrates, like littoral sediments and pleuston, which included several aquatic macrophytes species, from 31 localities (lentic and lotic) belonging to different riverine systems. Eight darwinulid species were found, representing all genera from this family. Alicenula serricaudata, Vestalenula pagliolii, and Penthesilenula brasiliensis were the most common species. Cluster analysis based on the composition and abundance of darwinulid communities revealed the presence of five associations. Darwinula stevensoni, Vestalenula botocuda, and Penthesilenula aotearoa were almost exclusive to lotic environments. A Mantel multiple test showed that the occurrence and distribution of darwinulid ostracods were significantly related to types of habitat and systems, but not to abiotic variables. It thus seems that the hydrodynamic fluctuations of these environments are probably more important to darwinulid distribution than the limnological characteristics.

A 4-yr (2002-2006) entomological study was carried out in Kurnool district, Andhra Pradesh state, south India, to identify the mosquito vectors of Japanese encephalitis virus (family Flaviviridae, genus Flavivirus, JEV). In total, 37,139 female mosquitoes belonging five genera and 18 species resting on vegetation were collected in villages and periurban areas at dusk. Mosquito species composition and pattern of JEV infection in mosquitoes varied in periurban and rural areas. In periurban area, Culex gelidus Theobald was abundant, making up 49.7% of total catch followed by Culex tritaeniorhynchus Giles (44.5%). In rural area, Cx. tritaeniorhynchus was predominant, making up 78.9% of total catch followed by Culex quinquefasciatus Say (10.8%), Anopheles subpictus Grassi (7.1%), and Cx. gelidus (1.1%). In light trap collections, Cx. gelidus and Cx. tritaeniorhynchus predominated in periurban and rural areas, respectively. Of 50,145 mosquitoes screened JEV isolations were made only from Cx. gelidus and Cx. tritaeniorhynchus. Based on high abundance and frequent JEV isolation, Cx. tritaeniorhynchus was found to be the principal vector in both areas, whereas Cx. gelidus plays a secondary vector role in periurban areas only.