Mosquitoes are members of family Culicidae of order Diptera. The family is a large and abundant group that occurs throughout temperature and tropical region of the world. It consists of three subfamilies (1) Anophelinae (2) Culicinae (3) Toxorhychitinae. There are 3500 species of mosquitoes in the world (Harbach and Howard, 2007) and 49 species (34 Anopheles, ten Culex, two Aedes, two Mansonia and one Armigeres) in Myanmar. Mosquitoes are the single largest group of insects, which serve as intermediate hosts in the transmission of many important human diseases carry number of vector borne diseases. They are including malaria, dengue hemorrhage fever (DHF), yellow fever, filariasis, chikungunya and Japanese encephalitis (JE) [1] and now recently found Zika virus which cause the microcephaly in fetus [1]. Malaria has been a priority health problem in Myanmar. Morbidity and mortality rate were 6.44/1000population and 0.48/ 1000,000 populations respectively in 20131. An.dirus and An.minimus are major vectors of malaria in forested and forested foot hill areas of the country and An.annularis is a local vector of malaria in Rakhine State. An.sundaigus and An.subpictus are abundantly found in coastal areas of Rakhine, Mon and Taninthayi Regions. An.maculipennis in Europe, An.culicifacies in the Indian Subcontinent, An.dirus, An.annularis, An.leucosphyrus, An.fluviatilis, An.maculatus, An.minimus, An.subpictus, An.philippnensis and An. nivipes in South-East Asia and they are important vectors of malaria in different parts of the world2. Anopheles culicifacies Giles has wide distribution in India and have five sibling species and extends up to Ethiopia, Yemen, Iran, Afghanistan and Pakistan in the west and An.minimus and An.dirus sibling species also distributed in Bangladesh, Myanmar, Thailand, Cambodia, China and Vietnam in the east [2]. The transmission of malaria is largely influence by the abundance, survival and bionomics of the mosquito vectors [3]. It is essential to detect occurrence of Anopheles mosquitoes in selected areas of Taikky Township Yangon Region. The results of the study can be supported to control vector of malaria by vector borne diseases control programme. Therefore, updating and better understanding of the occurrence of malaria vector mosquitoes are required monitoring of the species distribution of Anopheles mosquitoes in the study areas.

Objects of the Study

To determine the monthly occurrence of malaria vector mosquitoes in two selected areas in Taikky Township Yangon Region. To record the Anopheles species composition of mosquitoes in studied areas.

Study Site

Two study sites such as Ter Gwa and Kyaryet gyi villages were selected for monthly animal bait Anopheles mosquito’s collection in Taikkyi Township, Yangon Region.

Study Period

The study was done from January to August 2018. Sample collection method: Outdoor cattle bait mosquitoes collection was done using WHO sucking tube from 18:00 hours to 24hours for 3 days from January to August 2018. Anopheles mosquitoes were collected for 45 minutes in every hour on the cattle body. Hourly collected mosquitoes were placed in labeled paper cups. Next day morning all collected mosquitoes were classified the species. Larval survey was done in and around three kilometer away from the study sites.

Species Identification

The species identification of all collected mosquitoes from the 

cattle body was identified by [4,5].

Analysis

Monthly collected entomological data were analyzed by Microsoft excel software.

Results

Systematic position of studied species of Anopheles

Phylum: Arthropoda

Class: Insecta

Order: Diptera

Family: Culicidae

Genus: Anopheles

Species

• annularis
• vagus
• barbirostris
• aconitus
• fluviatilis
• philippinensis
• jamesii
• ramesii
• minimus
• stephensi
• tessallatus
• Maculatus

Table 1: Monthly occurrence of Anopheles mosquitoes in Targwa village Taikkyi Township.

(Table 1) shows that a total of 855 Anopheles mosquitoes belonging 12 species of Anopheles mosquitoes were collected in Targwa village within 10 months of the study period. Of this An.vagus was found highest number 527(61.64%) followed by An. barbirostris and An. aconitus 139 (16.26%) each and lowest was found An. fluviatilis, An.minimus and An.ramesii 3(0.35%) each. Monthly distribution of Anopheles mosquitoes were found highest number 441(52%) in March followed by 168 (20%) in July and lowest mosquitoes were caught in January and May 13(1.52%) each. Highest number 325 and 102 of An.vagus were collected in March and July followed by An. aconitus 162 in March and An.barbirostris 56. Anopheles vagus was caught in highest number in all months except January and February. Main malaria vector An. minimus was collected in the months of March, June and July in small number.

Table 2: Monthly occurrence of Anopheles mosquitoes in Kyaryetgyi village, Taikkyi Township.

(Table 2) Shows that a total of 1439 Anopheles mosquitoes belonging 12 species of Anopheles mosquitoes were collected in Kyaryetgyi village within 10 months of the study period. Of this An.vagus was found highest number 737(51.22%) followed by An. barbirostris 268(18.62%) and An. aconitus 244(16.96%) and lowest was found An.tessallatus 10(0.69%). Monthly distribution of Anopheles mosquitoes were found highest number 783(54.4%) in March followed by 237 (16.5%) in July and lowest mosquitoes were caught in February 19(1.32%). Highest number 416 An.vagus were collected in March and followed by An. aconitus 189 and An.barbirostris 93 in March. Anopheles vagus was caught in highest number in all months except January and February. Main malaria vector An. minimus was collected in the months of March, June, July and August in low number.

Table 3: Type of mosquito’s species adult emerged from larval survey collected from study areas.

(Table 3) shows that An. minmus larvae were collected in rice fields and An. vagus, a barbirostris and An. maculatus larvae were collected in water pools. An. berbirostris only was collected in ponds.

Malaria remains a major health problem in Myanmar. Anopheles dirus and Anopheles minimus are the main vectors of malaria but Anopheles maculatus, Anopheles vagus, Anopheles annularis, Anopheles philippnensis, Anopheles stiphensi and Anopheles culicifacies are secondary or suspected vectors of malaria in Myanmar. Aim of the present study was to know the prevalence of Anopheles mosquitoes in previously malaria endemic areas. Therefore the study was conducted in Taikkyi Township Yangon Region from January 2018 to September 2018. In the present study highest number of An. vagus were collected in all months in both Targwa and Kyaryetgyi villages followed by An. barbirostris and An. aconitus lowest was found An. ramesii. Main malaria vector An. minimus was collected in the months of March, June and July in small number in Targwa village and March, June, July and August in Kyaryetgyi villages. Anopheles minimus and Anopheles dirus are main vector of malaria in Myanmar and Anopheles minimus were found in high numbers in forest fringe foot hill and plain areas in the country. Other researcher revealed that a total of 1153 Anopheles mosquitoes belonging to 6 Anopheles species, Anopheles minimus was found the highest number 553 (47.96%) than followed by Anopheles maculatus in Pyin Oo Lwin Township. Minimus was observed in high density due to the fact that paddy fields and plenty of slowly running water places were available in and around the study area. In Kamamaung Township a total of 2106 Anopheles mosquitoes belonging to 9 species were collected, of this 524 and 429 Anopheles mosquitoes were collected from Katine Htit and Kine Taw villages. Anopheles culicifacies was found highest density i.e. 103 (19.65%) and 99 (23.08%) followed by Anopheles minimus 93 (17.75%) and 92 (21.46%) in both Katine Htit and Kine Taw villages respectively. It may be due to the fact that plenty of sand pools and slowly running water areas were available in the band of Yonsalin Creek and Anopheles culicifacies and Anopheles minimus larvae were abundantly bred together in these places. The main vector Anopheles dirus adult was collected in both Katine Htit and Kine Taw village by animal and human bait collections and larvae were collected in domestic water wells in both villages of Kamamaung Township .Same result has been found in the preset study for An. minimus and it larvae were mostly found in rice field although An vagus, An. barbirostris and An. aconitus were found high number in both village and larvae were found in water pools. In Pyin Oo Lwin, Anopheles minimus a larvae were found in slowly running water and rice field [6]. The result are agreed with the previous researchers, they revealed that Anopheles minimus larvae were mostly found in rice field and slowly running water in Taungoo Township and slowly running small jungle stem of Yeasitkan village of Taikkyi Township . Although Anopheles culicifacies larvae were abundantly found in ponds in Solana village in India, rock creek in Gonminsoe village in Paukkaung Township Bago Region and sand pools of Sedawgyi canal in Madaya Township Mandalay Region [7]. Anopheles dirus larvae were collected from domestic water wells in raining and cold seasons in both villages. Other researchers revealed that Anopheles dirus larvae were abundantly found in rock pools in forested hilly areas of Bago Yoma, Oktwin Township, Bago Region and also larvae were found in domestic water wells in Mon state and Thaninthayi Region, Bamboo stumps in deep forest areas [8]. The pick biting time of both main vector Anopheles minimus and Anopheles dirus were found 11: 00 pm for Anopheles minimus and 10:00pm for Anopheles dirus in both areas it was agreed with the other researchers finding who were worked in Bago Yoma, Taikkyi Township Yangon Region, Mon state and Taninthayi Region [9-12] Present study observed that collected Anopheles minimus from both Pyin Oo Lwin and Kamamaung were species complex A. Anopheles culicifacies is a co-breeder of Anopheles minimus A. Anopheles minimus a larvae were collected in high number in sand pools and slowly running water of Younsalin creeks, and the larvae were bred together with Anopheles culicifacies larvae in both villages of Kamamaung. In Pyin Oo Lwin, Anopheles minimus A larvae were found in slowly running water and rice field. The result are agreed with the previous researchers, they revealed that  Anopheles minimus larvae were mostly found in rice field and slowly running water in Taungoo Township and slowly running small jungle stem of Yeasitkan village of Taikkyi Township . Although Anopheles culicifacies larvae were abundantly found in ponds in Solana village in India, rock creek in Gonminsoe village in Paukkaung Township Bago Region and sand pools of Sedawgyi canal in Madaya Township Mandalay Region [13-15]. Anopheles dirus larvae were collected from domestic water wells in raining and cold seasons in both villages. Other researchers revealed that Anopheles dirus larvae were abundantly found in rock pools in forested hilly areas of Bago Yoma, Oktwin Township, Bago Region and also larvae were found in domestic water wells in Mon state and Thaninthayi Region, Bamboo stumps in deep forest areas [16,17]. Although in Myanmar vector incrimination study of Anopheles culicifacies B were found sporozoite negative. Other researcher found that vector incrimination study of Anopheles dirus, Anopheles minimus, Anopheles kochi and Anopheles maculatus were circumsporozoite antigen positive in Bokpyin Township in Tanintharyi Region and Anopheles minimus and Anopheles culicifacies were found circumsporozoite antigen positive in Ann Township, Rakhaine State. Other study found that 3.57% of Anopheles minimus and 0.54% of Anopheles maculatus were sporozoite positive in Taikkyi Township Yangon Region. The present study concluded that the presence of Anopheles minimus in studied areas as Targwa and Kyaryetgyi villages in Taikkyi Township, Yangon Region in Myanmar is a serious problem. Because Anopheles minimus is a main vector of malaria and An. aconitus, An. maculatus, An. tessallatus, An. jamesii, An. philippeninsis, a ramesii and An.stephnensis are secondary vectors in the study areas. A detailed sporozoite study is needed for the identification of the role of Anopheles mosquitoes in present studied areas of previously malaria endemic areas of Myanmar, in order to establish existence and distribution of Anopheles mosquitoes and its vectorial capacity and status of malaria in Myanmar.

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