Molecular variation and distribution of Anopheles fluviatilis (Diptera: Culicidae) complex in Iran

Are members of the Anopheles fluviatilis complex conspecific?

Anopheles fluviatilis sensu lato, a primary malaria vector in India, has been identified to be comprised of four cryptic species, provisionally designated as species S, T, U and V. However, Kumar et al. (Mol Ecol Resour, 2013;13:354-61) considered all of the then known three members of this species complex (S, T and U) conspecific. The specific status of species S and T was refuted based on the lack of sufficient barcode gap in mitochondrial-CO1 and the perceived presence of heterozygotes in populations as detected through one of the two species-specific PCR assays employed for the cryptic species identification. The existence of species U was refuted claiming that earlier investigations have already refuted their existence. Here we discuss problems associated with the CO1-based barcode approach for delimitation of cryptic species, the perceived heterozygosity between species S and T based on a species-specific PCR assay, and interpretation of published reports. We demonstrated that fixed differences do exist in the ITS2-rDNA sequence of species S and T with no evidence of heterozygotes in sympatric populations and, that the observed heterozygosity by Kumar et al. in the ITS2-based species diagnostic PCR is due to the high mispriming tendency of the T-specific primer with species S. We infer that mitochondrial DNA-based 'barcoding gap', an arbitrary threshold recommended for species delimitation, alone, is inadequate to delimit the members of An. fluviatilis complex.

Utility of Complete Mitochondrial Genomes in Phylogenetic Classification of the Species of Anopheles (Culicidae: Anophelinae)

Background:

Among the blood-sucking insects, Anopheles mosquitoes have a very special position, because they transmit parasites of the genus Plasmodium, which cause malaria as one of the main vector-borne disease worldwide. The aim of this review study was to evaluate utility of complete mitochondrial genomes in phylogenetic classification of the species of Anopheles.

Methods:

The complete mitochondrial genome sequences belonging to 28 species of the genus Anopheles (n=32) were downloaded from NCBI. The phylogenetic trees were constructed using the ML, NJ, ME, and Bayesian inference methods.

Results:

In general, the results of the present survey revealed that the complete mitochondrial genomes act very accurately in recognition of the taxonomic and phylogenetic status of these species and provide a higher level of support than those based on individual or partial mitochondrial genes so that by using them, we can meticulously reconstruct and modify Anopheles classification.

Conclusion:

Understanding the taxonomic position of Anopheles, can be a very effective step in better planning for controlling these malaria vectors in the world and will improve our knowledge of their evolutionary biology.

A detailed review of the mosquitoes (Diptera: Culicidae) of Iran and their medical and veterinary importance

Mosquitoes (Diptera: Culicidae) are the most significant arthropods of medical importance because of the burden of diseases, such as malaria, encephalitis and filariasis, which are caused by pathogens and parasites they transmit to humans. In 2007, the most recently published checklist of Iranian mosquitoes included 64 species representing seven genera. Public databases were searched to the end of August 2018 for publications concerning the diseases in Iran caused by mosquito-borne pathogens. Pertinent information was extracted and analyzed, and the checklist of Iranian mosquitoes was updated. Six arboviral diseases, two bacterial diseases, four helminthic diseases and two protozoal diseases occur in Iran. The agents of these diseases are biologically or mechanically known or assumed to be transmitted by mosquitoes. The updated checklist of Iranian mosquitoes includes 69 species representing seven or 11 genera depending on the generic classification of aedines. There is no published information about the role of mosquitoes in the transmission of the causal agents of avian malaria, avian pox, bovine ephemeral fever, dengue fever, Rift Valley fever, Sindbis fever, Deraiophoronema evansi infection, lymphatic filariasis, anthrax and tularemia in Iran. There is just one imported case of lymphatic filariasis, which is not endemic in the country. It seems arthropods do not play an important role in the epidemiology of anthrax and ixodid ticks are the main vectors of the tularemia bacterium. In view of the recent finding of only a few adults and larvae of Aedes albopictus in southeastern Iran and the absence of Ae. aegypti, it is not possible to infer the indigenous transmission of the dengue fever virus in Iran. Considering the importance of mosquito-borne diseases in the country, it is necessary to improve vector and vector-borne disease surveillance in order to apply the best integrated vector management interventions as a part of the One Health concept.

The Role of Molecular Techniques on Malaria Control and Elimination Programs in Iran: A Review Article

BACKGROUND

The aim of this review was to describe the application of molecular methods in epidemiological aspects of malaria vectors, parasites, and human hosts in Iran and their critical role in malaria control and elimination programs.

METHODS

Medline, EMBASE, Web of Science, Scopus, and Google Scholar databases were searched systematically for original published papers on PCR, the molecular identification of malaria vectors, the molecular epidemiology of malaria, insecticide resistance, and drug-resistant parasites, in Iran. In total, 51 studies on molecular entomology and 36 studies on molecular parasitology of malaria and three on human host were selected.

RESULTS

Molecular methods are essential for improving the detection of malaria infection and monitoring antimalarial drugs and insecticide resistance in malaria elimination settings such as Iran.

CONCLUSION

The application of molecular methods may be of particular interest for malaria control/elimination programs, for monitoring progress towards malaria elimination, and for optimal orientation of program activities.

Spatial changes in the distribution of malaria vectors during the past 5 decades in Iran

BACKGROUND

Global warming and climate change affect various aspects of mankind, including public health. Anopheles mosquitoes are of Public Health importance and can be affected by global warming and other environmental variables. Here, we studied the distribution of Anopheles vectors of malaria in relation to environmental variables in Iran.

METHODS

Long-term meteorological and entomological data of about 50 years in retrospect were collected and arranged in a geo-database and analyzed using ArcGIS ver. 9.3 and exported to SPSS ver. 20 for statistical analysis.

RESULTS

Distribution maps have been updated for seven species of Anopheles vectors of malaria which involved Anopheles culicifacies s.l., An. fluviatilis s.l., An. stephensi, An. dthali, An. sacharovi, An. maculipennis.l. and An. superpictus in Iran. Distribution maps of vectors were made based on district areas using Kriging model. Historical and recent records were demonstrated for each Anopheles based on climatic factors in the distribution areas of each Anopheles vectors.

DISCUSSION

Iran, like other parts of the world is faced with warming and this probably affected the distribution of Anopheles vectors. Despite the warming phenomenon, the country's climate had changed during the cold season as temperatures became colder or cooler. This study shows that some vectors had migrated from the central part of Iran with dry and sunny landscape, moved towards the mountainous areas of the north or the warm and humid areas of the south. Historical records show that these anophelines have previously been distributed in lowland areas. If this process continues in the future, Anopheles mosquitoes may be seen in low lands with cold areas in central and northern parts of the country or will occupy humid and warm climates in the southern parts of the country where water is more available.

An evaluation of the suitability of COI and COII gene variation for reconstructing the phylogeny of, and identifying cryptic species in, anopheline mosquitoes (Diptera Culicidae)

We assessed the practicality and effectiveness of using variation in the mitochondrial COI and COII genes to discriminate species and reconstruct the phylogeny of anophelene mosquitoes. Phylogenetic relationships among the subfamily Anophelinae were inferred from portions of the mitochondrial COI (92 species) and COII genes (108 species). Phylogenetic trees were reconstructed on the basis of parsimony, maximum likelihood and Bayesian methods. The suitability of COI and COII gene variation for identifying cryptic species was compared by comparing the sequence divergence within species groups and complexes. The results show that the COI gene was more useful for identifying sibling and cryptic species, but that phylogenetic relationships reconstructed using the COII gene were more similar to those based on morphological data. We conclude that: (1) there is a significant molecular divergence among An. sinensis; (2) the COI and COII are valid genetic markers for resolving taxonomic relationships among anopheline mosquitoes and the resultant phylogeny raises some questions about the taxonomic status of anopheline species groups and complexes; (3) the genus Anopheles is not demonstrably monophyletic with regard to the genus Bironella; (4) the subgenera Kerteszia and Nyssorhynchus are monophyletic; (5) below the group-level, COI data support the existence of monophyletic taxa within the Anopheles funestus, Anopheles maculipennis and Anopheles strode and Anopheles barbirostris subgroups, and within the Anopheles nuneztovari complex, whereas COII data support the monophyletic taxa within the Anopheles minimus and Anopheles oswaldoi subgroups, and Anopheles hyrcanus group. The monophyletic taxa within the Anopheles gambiae and Anopheles albitarsis complexes are supported by both COI and COII data.

The Fauna and Ecology of Mosquitoes (Diptera: Culicidae) in Western Iran

BACKGROUND

The aim of this study was to obtain new data which would be valuable to develop programs for future planning of mosquito controls in in western Iran.

METHODS

Larvae and adult collections were carried out from different habitats using standard dipping and animal baited trap methods during May, June and July 2012 in two provinces (Kurdistan and Kermanshah) in the west of Iran. Characteristics of breeding places were studied based on the habitat type (River edge, Ground pool), water conditions (clear or turbid, stagnant or running), vegetation (With or without vegetation), water temperature, sunlight exposure (full or partial sunlight) and so on.

RESULTS

Overall, 4081 third- and fourth-instars larvae and 2013 Adult were collected. Five genera and eleven species of the family Culicidae were identified. Mosquitoes collected in larval and adult stages including, Anopheles maculipennis s.l. (4.1%, 4.42%), An. superpictus (1.35%,1.39%), An. turkhudi (1.75%,1.68%), Aedes vexans (2.5%, 8.78%), Culex hortensis (1.59%, 1.04%), Cx. mimeticus (5%, 2.38%), Cx. pipiens (16.5%, 8.15%), Cx. theileri (10%, 46.4%), Culiseta longiareolata (24%, 4.27%), and Cs. subochrea (24%, 4.27%) and Ochlerotatus caspius s.l. (9.1%, 21.46%). Culiseta longiareolata and Cs. subochrea found predominant species in larval collection, whereas Culex theileri was dominant in Adult collection. Anopheles turkhudi is reported for the first time in Kermanshah Province.

CONCLUSION

Due to the geographical location of the two provinces, extensively studies with emphasis on mosquito ecology, to having comprehensive and up to date information is essential.

Fauna and Larval Habitats of Mosquitoes (Diptera: Culicidae) of West Azerbaijan Province, Northwestern Iran

BACKGROUND

Several important diseases are transmitted by mosquitoes. Despite of the potential of the occurrence of some mosquito-borne diseases such as West Nile, dirofilariasis and malaria in the region, there is no recent study of mosquitoes in West Azerbaijan Province. The aim of this investigation was to study the fauna, composition and distribution of mosquitoes and the characteristics of their larval habitats in this province.

METHODS

Larvae and adult collections were carried out from different habitats using the standard methods in twenty five localities of seven counties across West Azerbaijan Province.

RESULTS

Overall, 1569 mosquitoes including 1336 larvae and 233 adults were collected from 25 localities. The details of geographical properties were recorded. Five genera along with 12 species were collected and identified including: Anopheles claviger, An. maculipennis s.l., An. superpictus, Culex pipiens, Cx. theileri, Cx. modestus, Cx. hortensis, Cx. mimeticus, Culiseta Longiareolata, Ochlerotatus caspius s.l., Oc. geniculatus and Uranotaenia unguiculata. This is the first record of Oc. geniculatus in the province.

CONCLUSION

Due to the geographical location of the West Azerbaijan Province, it comprises different climatic condition which provides suitable environment for the establishment of various species of mosquitoes. The solidarity geographical, cultural and territorial exchanges complicate the situation of the province and its vectors as a threat for future and probable epidemics of mosquito-borne diseases.

Malaria elimination trend from a hypo-endemic unstable active focus in southern Iran: predisposing climatic factors

Human malaria is the most important vector-borne infectious disease in Iran. It remains focally endemic being restricted to almost 20 counties in three oriental provinces. As a result of control measures applied since 1988, these counties appear to be on the verge of eliminating malaria. Malaria elimination strategy has thus become the new goal in Iran. Malaria due to Plasmodium vivax, whose transmission is particularly hard to interrupt, accounts for nearly 90% of the cases. This study was thus undertaken to show malaria elimination trend from a hypo-endemic unstable active focus in southern Iran and to examine the role of prevailing climatic factors. This focus is now under elimination phase (Stratum III or annual parasitic index <1/1000 person/year). All malaria-positive cases were identified with active and passive procedures from 2003 to 2011. Although all ages were infected, more than half of the patients were in the higher than 20-year age group and a clear majority (77%) of them identified in the warmer months (May-October) of the year were positive with P. vivax parasites. The rate of falciparum to mixed infections was highest (1%) in the penultimate year. Case finding was negatively related to precipitation rate both annually and over the 9-year period and positively to ambient temperature in each year. Despite progress in the scale-up of its elimination, transmission of malaria remains active. This should be tackled by proactive case detection in specific hotspots of the study focus.

Molecular phylogenetic analysis of Anopheles and Cellia subgenus anophelines (Diptera: Culicidae) in temperate and tropical regions of Iran

Molecular studies on population genetics of speciation across Iran have recently started. Morphological and molecular studies have showed that 25 species of genus Anopheles are present in the country; however, relationships between vector and non-vector species as well as compatibility of morphological characters with molecular data have not been verified. Molecular phylogenetic analysis was undertaken on the Anopheles and Cellia subgenus members internal transcribed spacer 2 (ITS2) sequences submitted to GenBank among the Oriental and Palearctic members in north and southern Iran. rDNA-ITS2 sequences were extracted from the GenBank and analyzed using bioinformatics softwares: BLAST, ITS2 annotation tool (version 3.0.13), ClustalW, and MEGA5 in neighbor-joining and maximum likelihood algorithms. There are not any submitted sequences in GenBank from Iran for the following seven species: Anopheles algeriensis, Anopheles marteri, Anopheles plumbeus, Anopheles peditaeniatus, Anopheles melanoon, Anopheles subpictus, and Anopheles mongolensis; therefore, they have not been included in the study. Although these molecular-based phylogenetic trees match well enough with classical morphological taxonomy, the arrangement of species did not match with morphological classification in some cases. Correct species identification is essential for control of vector born disease such as malaria; therefore, phylogenetic methods will help to understand the relationship among the members of the target species within the genus Anopheles. It could also help us to design molecular markers for species differentiation particularly in cryptic species, which is difficult to classify them based on morphological features.

Confirmation of Two Sibling Species among Anopheles fluviatilis Mosquitoes in South and Southeastern Iran by Analysis of Cytochrome Oxidase I Gene

BACKGROUND

Anopheles fluviatilis, one of the major malaria vectors in Iran, is assumed to be a complex of sibling species. The aim of this study was to evaluate Cytochrome oxidase I (COI) gene alongside 28S-D3 as a diagnostic tool for identification of An. fluviatilis sibling species in Iran.

METHODS

DNA sample belonging to 24 An. fluviatilis mosquitoes from different geographical areas in south and southeastern Iran were used for amplification of COI gene followed by sequencing. The 474-475 bp COI sequences obtained in this study were aligned with 59 similar sequences of An. fluviatilis and a sequence of Anopheles minimus, as out group, from GenBank database. The distances between group and individual sequences were calculated and phylogenetic tree for obtained sequences was generated by using Kimura two parameter (K2P) model of neighbor-joining method.

RESULTS

Phylogenetic analysis using COI gene grouped members of Fars Province (central Iran) in two distinct clades separate from other Iranian members representing Hormozgan, Kerman, and Sistan va Baluchestan Provinces. The mean distance between Iranian and Indian individuals was 1.66%, whereas the value between Fars Province individuals and the group comprising individuals from other areas of Iran was 2.06%.

CONCLUSION

Presence of 2.06% mean distance between individuals from Fars Province and those from other areas of Iran is indicative of at least two sibling species in An. fluviatilis mosquitoes of Iran. This finding confirms earlier results based on RAPD-PCR and 28S-D3 analysis.

Spatio-temporal distribution of malaria vectors (Diptera: Culicidae) across different climatic zones of Iran

Malaria is a main vector-borne public health problem in Iran. The last studies on Iranian mosquitoes show 31 Anopheles species including different sibling species and genotypes, eight of them are reported to play role in malaria transmission. The objective of this study is to provide a reference for malaria vectors of Iran and to map their spatial and temporal distribution in different climatic zones. Shape files of administrative boundaries and climates of Iran were provided by National Cartographic Center. Data on distribution and seasonal activity of malaria vectors were obtained from different sources and a databank in district level was created in Excel 2003, inserted to the shape files and analyzed by ArcGIS 9.2 to provide the maps. Anopheles culicifacies Giles s.l., Anopheles dthali Patton, Anopheles fluviatilis James s.l., Anopheles maculipennis Meigen s.l., Anopheles sacharovi Favre, Anopheles stephensi Liston, and Anopheles superpictus Grassi have been introduced as primary and secondary malaria vectors and Anopheles pulcherrimus Theobald as a suspected vector in Iran. Temporal distribution of anopheline mosquitoes is restricted to April-December in northern Iran, however mosquitoes can be found during the year in southern region. Spatial distribution of malaria vectors is different based on species, thus six of them (except for Anopheles maculipennis s.l. and Anopheles sacharovi) are reported from endemic malarious area in southern and southeastern areas of Iran. The climate of this part is usually warm and humid, which makes it favorable for mosquito rearing and malaria transmission. Correlation between climate conditions and vector distribution can help to predict the potential range of activity for each species and preparedness for malaria epidemics.