Evolution of mitochondrial and ribosomal gene sequences in anophelinae (Diptera: Culicidae): implications for phylogeny reconstruction

The insupportable validity of mosquito subspecies (Diptera: Culicidae) and their exclusion from culicid classification

Beginning about 80 years ago, the recognition of morphological varieties of mosquitoes was gradually replaced by the recognition of subspecies. As an examination of revisionary and detailed taxonomic studies of mosquitoes clearly shows, subspecies are untenable concepts which have been synonymized with nominotypical forms or recognized as distinct species. Thus, from our perspective, subspecies is not a functional or practical taxonomic rank. Consequently, in this study we critically assessed the taxonomic status of the 120 nominal taxa distinguished as subspecies before now to determine whether they should be recognized as separate species or synonymous names. As a result, 96 subspecies are formally elevated to specific rank, 22 are relegated to synonymy with nominotypical forms, one is considered a nomen dubium, one a species inquirenda and the names of four nominal species regarded as synonyms are revalidated. The subspecies and their new status are listed in a conspectus. The revalidated species include Anopheles argentinus (Brèthes, 1912), from synonymy with An. pseudopunctipennis Theobald, 1901c; An. peruvianus Tamayo, 1907, from synonymy with An. pseudopunctipennis as nomen dubium; Culex major Edwards, 1935, from synonymy with Cx. annulioris consimilis Newstead, 1907; and Trichoprosopon trichorryes (Dyar & Knab, 1907), from synonymy with Tr. compressum Lutz, 1905. Additionally, the type locality of Anopheles sergentii Theobald, 1907 is restricted to El Outaya, Biskra Province, Algeria. A complete list of species to be retained, added to or removed from the Encyclopedia of Life, with a few corrections, is provided.

DDT Resistance in Anopheles pharoensis from Northern Cameroon Associated with High Cuticular Hydrocarbon Production

Despite the contribution of secondary vectors to malaria transmission, there is still not enough information on their susceptibility status to insecticides. The present study assesses the resistance profile of Anopheles pharoensis to DDT. WHO tube tests were used to screen mosquito populations collected from the far-north region of Cameroon for susceptibility to 4% DDT. High DDT resistance in An. pharoensis populations from Maga, Simatou and Yangah with mortality rates ranging from 62.79% to 80% was recorded. Direct sequencing (Sanger) of the VGSC gene was undertaken to search for kdr L1014F/S mutations. However, no kdr allele was detected in the resistant samples. We then looked for cuticle alterations and CHC identification and quantitation were undertaken using GC-MS and GC-FID. High production of cuticular hydrocarbon was recorded in the populations of Yangah and Simatou, with 2420.9 ± 265 and 2372.5 ± 225 ng CHCs/mg dry weight, respectively. The present findings are the first ever describing the development of cuticle resistance in An. pharoensis. The data suggest the need to expand surveillance activities on other vector species.

Molecular Characterization of Anopheles algeriensis Theobald, 1903 (Diptera: Culicidae) Populations from Europe

Anopheles algeriensis Theobald, 1903, considered a competent vector of Plasmodium parasites, is a mosquito species widely distributed in the Mediterranean area but rare in Northern and Central Europe. The disappearance of its suitable breeding sites in Italy is having a detrimental effect on the occurrence of this species once common along the Southern coasts and on the islands. Recently, molecular investigations have renewed interest in this species, highlighting a genetic heterogeneity among European populations. In this study, An. algeriensis populations from Italy, Germany, Romania, and Sweden were analyzed by molecular typing of the intergenic transcribed spacer 2 (ITS2). The mitochondrial cytochrome c oxidase subunit I (COI) was also analyzed from specimens collected in Southern Italy. With the aim of investigating the population structure of this species, the obtained data were compared to all publicly available ITS2 and COI sequences of An. algeriensis, adding specimens from Spain and Portugal. The analyses of both markers indicate a split between Iberian populations (Spain for ITS2 and Spain/Portugal for COI) and those from the rest of Europe, revealing two cryptic species. The analysis of the COI barcode revealed a third clade representing a cryptic species present in Danube Delta (Romania). The high levels of genetic divergence among the clades of An. algeriensis indicate that this taxon represents a species complex, potentially harboring several distinct cryptic species.

Multiple Novel Clades of Anopheline Mosquitoes Caught Outdoors in Northern Zambia

Residual vector populations that do not come in contact with the most frequently utilized indoor-directed interventions present major challenges to global malaria eradication. Many of these residual populations are mosquito species about which little is known. As part of a study to assess the threat of outdoor exposure to malaria mosquitoes within the Southern and Central Africa International Centers of Excellence for Malaria Research, foraging female anophelines were collected outside households in Nchelenge District, northern Zambia. These anophelines proved to be more diverse than had previously been reported in the area. In order to further characterize the anopheline species, sequencing and phylogenetic approaches were utilized. Anopheline mosquitoes were collected from outdoor light traps, morphologically identified, and sent to Johns Hopkins Bloomberg School of Public Health for sequencing. Sanger sequencing from 115 field-derived samples yielded mitochondrial COI sequences, which were aligned with a homologous 488 bp gene segment from known anophelines (n = 140) retrieved from NCBI. Nuclear ITS2 sequences (n = 57) for at least one individual from each unique COI clade were generated and compared against NCBI’s nucleotide BLAST database to provide additional evidence for taxonomical identity and structure. Molecular and morphological data were combined for assignment of species or higher taxonomy. Twelve phylogenetic groups were characterized from the COI and ITS2 sequence data, including the primary vector species Anopheles funestus s.s. and An. gambiae s.s. An unexpectedly large proportion of the field collections were identified as An. coustani and An. sp. 6. Six phylogenetic groups remain unidentified to species-level. Outdoor collections of anopheline mosquitoes in areas frequented by people in Nchelenge, northern Zambia, proved to be extremely diverse. Morphological misidentification and underrepresentation of some anopheline species in sequence databases confound efforts to confirm identity of potential malaria vector species. The large number of unidentified anophelines could compromise the malaria vector surveillance and malaria control efforts not only in northern Zambia but other places where surveillance and control are focused on indoor-foraging and resting anophelines. Therefore, it is critical to continue development of methodologies that allow better identification of these populations and revisiting and cleaning current genomic databases.

Culicidae evolutionary history focusing on the Culicinae subfamily based on mitochondrial phylogenomics

Mosquitoes are insects of medical importance due their role as vectors of different pathogens to humans. There is a lack of information about the evolutionary history and phylogenetic positioning of the majority of mosquito species. Here we characterized the mitogenomes of mosquito species through low-coverage whole genome sequencing and data mining. A total of 37 draft mitogenomes of different species were assembled from which 16 are newly-sequenced species. We datamined additional 49 mosquito mitogenomes, and together with our 37 mitogenomes, we reconstructed the evolutionary history of 86 species including representatives from 15 genera and 7 tribes. Our results showed that most of the species clustered in clades with other members of their own genus with exception of Aedes genus which was paraphyletic. We confirmed the monophyletic status of the Mansoniini tribe including both Coquillettidia and Mansonia genus. The Aedeomyiini and Uranotaeniini were consistently recovered as basal to other tribes in the subfamily Culicinae, although the exact relationships among these tribes differed between analyses. These results demonstrate that low-coverage sequencing is effective to recover mitogenomes, establish phylogenetic knowledge and hence generate basic fundamental information that will help in the understanding of the role of these species as pathogen vectors.

Molecular characterization and phylogenetic analysis of anopheline (Anophelinae: Culicidae) mosquitoes of the Oriental and Afrotropical Zoogeographic zones in Saudi Arabia

The Kingdom of Saudi Arabia (KSA) has a diverse fauna due to its peculiar position bordering the Afrotropical, Oriental and Palaearctic zoogeographic zones. The present study reports the phylogenetics of five mosquito species belonging to five series of Anopheles (Cellia) . We collected mosquito larvae from eastern, western and southwestern regions of KSA. The sampled mosquitoes were morphologically identified using the pictorial keys of mosquitoes and characterized by using single and multi-locus analysis of -internal transcribed spacer 2 (ITS2) region and cytochrome oxidase c subunit I (COI). Based on the morphological and molecular data, five species were recognized, like An. stephensi (Neocellia) (Oriental), An. arabiensis (Pyretophorus) (Afrotropical), An. dthali (Myzomyia) (Oriental and Palaearctic), An. cinereus (Paramyzomyia) and An. rhodesiensis rupicola (Neomyzomyia) (Oriental and Palaearctic). The phylogenetic analysis showed that An. stephensi is a monophyletic species with different ecotypes found in different geographic regions. Comprehensive phylogenetics and population genetics studies are crucial for a better understanding of the role of these five mosquito species in malarial transmission across various zoogeographic zones of different ecological and demographic characteristics.

Novel Mitochondrial DNA Lineage Found among Ochlerotatus communis (De Geer, 1776) of the Nordic-Baltic Region

The Ochlerotatus (Oc.) communis complex consist of three Northern American species as well as a common Holarctic mosquito (Diptera: Culicidae) Oc. communis (De Geer, 1776). These sister species exhibit important ecological differences and are capable of transmitting various pathogens, but cannot always be differentiated by morphological traits. To investigate the Oc. communis complex in Europe, we compared three molecular markers (COI, ND5 and ITS2) from 54 Estonian mosquitoes as well as two COI marker sequences from Sweden. These sequences were subjected to phylogenetic analysis and screened for Wolbachia Hertig and Wolbach symbionts. Within and between groups, distances were calculated for each marker to better understand the relationships among individuals. Results demonstrate that a group of samples, extracted from adult female mosquitoes matching the morphology of Oc. communis, show a marked difference from the main species when comparing the mitochondrial markers COI and ND5. However, there is no variance between the same specimens when considering the nuclear ITS2. We conclude that Oc. communis encompasses two distinct mitochondrial DNA lineages in the Nordic-Baltic region. Further research is needed to investigate the origin and extent of these genetic differences.

Culicidae-centric metabarcoding through targeted use of D2 ribosomal DNA primers

A practical limitation to many metabarcoding initiatives is that sampling methods tend to collect many non-target taxa, which become “amplicon noise” that can saturate Next Generation Sequencing results and lead to both financial and resource inefficiencies. An available molecular tool that can significantly decrease these non-target amplicons and decrease the need for pre-DNA-extraction sorting of bycatch is the design of PCR primers tailored to the taxa under investigation. We assessed whether the D2 extension segment of the 28S ribosomal operon can limit this shortcoming within the context of mosquito (Culicidae) monitoring. We designed PCR primers that are fully conserved across mosquitos and exclude from amplification most other taxa likely to be collected with current sampling apparatuses. We show that, given enough sequencing depth, D2 is an effective marker for the detection of mosquito sequences within mock genomic DNA pools. As few as 3,050 quality-filtered Illumina reads were able to recover all 17 species in a bulk pool containing as little as 0.2% of constituent DNA from single taxa. We also mixed these mosquito DNA pools with high concentrations of non-Culicidae bycatch DNA and show that the component mosquito species are generally still recoverable and faithful to their original relative frequencies. Finally, we show that there is little loss of fidelity in abundance parameters when pools from degraded DNA samples were sequenced using the D2 primers.

Characterization of the complete mitogenome of Anopheles aquasalis, and phylogenetic divergences among Anopheles from diverse geographic zones

Whole mitogenome sequences (mtDNA) have been exploited for insect ecology studies, using them as molecular markers to reconstruct phylogenies, or to infer phylogeographic relationships and gene flow. Recent Anopheles phylogenomic studies have provided information regarding the time of deep lineage divergences within the genus. Here we report the complete 15,393 bp mtDNA sequences of Anopheles aquasalis, a Neotropical human malaria vector. When comparing its structure and base composition with other relevant and available anopheline mitogenomes, high similarity and conserved genomic features were observed. Furthermore, 22 mtDNA sequences comprising anopheline and Dipteran sibling species were analyzed to reconstruct phylogenies and estimate dates of divergence between taxa. Phylogenetic analysis using complete mtDNA sequences suggests that A. aquasalis diverged from the Anopheles albitarsis complex ~28 million years ago (MYA), and ~38 MYA from Anopheles darlingi. Bayesian analysis suggests that the most recent ancestor of Nyssorhynchus and Anopheles + Cellia was extant ~83 MYA, corroborating current estimates of ~79–100 MYA. Additional sampling and publication of African, Asian, and North American anopheline mitogenomes would improve the resolution of the Anopheles phylogeny and clarify early continental dispersal routes.

Is Genetic Continuity Between Anopheles sinensis (Diptera: Culicidae) and its Sibling Species Due to Gene Introgression or Incomplete Speciation?

The Anopheles mosquito Hyrcanus Group is widely distributed geographically across both Palearctic and Oriental regions and comprises 26 valid species. Although the species Anopheles sinensis Wiedemann (1828) is the most common in China and has a low potential vector rank, it has nevertheless long been thought to be an important natural malaria vector within the middle and lower reaches of the Yangtze River. A number of previous research studies have found evidence to support the occurrence of natural hybridization between An. sinensis and Anopheles kleini Rueda, 2005 (a competent malaria vector). We, therefore, collected a sample series of An. sinensis and morphologically similar species across China and undertook ribosomal and mitochondrial DNA analyses in order to assess genetic differentiation (Fst) and gene flow (Nm) amongst different groups. This enabled us to evaluate divergence times between morphologically similar species using the cytochrome oxidase I (COI) gene. The results of this study reveal significant genetic similarities between An. sinensis, An. kleini, and Anopheles belenrae Rueda, 2005 and therefore imply that correct molecular identifications will require additional molecular markers. As results also reveal the presence of gene flow between these three species, their taxonomic status will require further work. Data suggest that An. kleini is the most basal of the three species, while An. sinensis and An. belenrae share the closest genetic relationship.

Intraspecific phylogeny of Anopheles (Kerteszia) neivai Howard, Dyar & Knab 1913, based on mitochondrial and nuclear ribosomal genes

Three mitochondrial regions and a fragment of a large nuclear ribosomal subunit was used to study the evolutionary patterns of An. neivai, a mosquito inhabiting mangroves and tropical forest in the lowland and coastal areas of the Yucatan Peninsula through the Pacific Ecuadorian coast. This species exhibits epidemiological importance regarding Malaria transmission in natural ecosystems, particularly in rural areas of the Pacific Colombian coast. The results based on phylogenetic networks and Bayesian inference showed no robust evidence supporting the existence of previously suggested cryptic species. Diversification patterns in geographically widespread species such as this one, are complex and therefore could impact malaria control strategies. Further studies focused on behavior, morphology, and phylogenomics will improve the understanding of the evolutionary patterns within An. neivai and its role as a disease vector.

An Anopheles by Any Other Name …?

The physical characteristics of a nematoceran fly that evokes the image of a mosquito of the genus Anopheles Meigen (Diptera: Culicidae) has existed since the genus was defined in the early part of the twentieth century. Is that image likely to change with the recent proposal to elevate four Neotropical subgenera to generic status based on relationships generated by phylogenetic analyses of mitochondrial protein-coding genes? Reasons for retaining the traditional concept of Anopheles, with its traditionally recognized subgenera, are presented. However, as the ranking of taxa as genera or subgenera is subjective, the choice of rank of a genus-group name may be considered a subjective decision and a matter of user preference.

First Molecular Identification and Phylogeny of Moroccan Anopheles sergentii (Diptera: Culicidae) Based on Second Internal Transcribed Spencer (ITS2) and Cytochrome c Oxidase I (COI) Sequences

Anopheles sergentii known as the "oasis vector" or the "desert malaria vector" is considered the main vector of malaria in the southern parts of Morocco. Its presence in Morocco is confirmed for the first time through sequencing of mitochondrial DNA (mDNA) cytochrome c oxidase subunit I (COI) barcodes and nuclear ribosomal DNA (rDNA) second internal transcribed spacer (ITS2) sequences and direct comparison with specimens of A. sergentii of other countries. The DNA barcodes (n = 39) obtained from A. sergentii collected in 2015 and 2016 showed more diversity with 10 haplotypes, compared with 3 haplotypes obtained from ITS2 sequences (n = 59). Moreover, the comparison using the ITS2 sequences showed closer evolutionary relationship between the Moroccan and Egyptian strains than the Iranian strain. Nevertheless, genetic differences due to geographical segregation were also observed. This study provides the first report on the sequence of rDNA-ITS2 and mtDNA COI, which could be used to better understand the biodiversity of A. sergentii.

Malaria parasites of long-tailed macaques in Sarawak, Malaysian Borneo: a novel species and demographic and evolutionary histories

Background

Non-human primates have long been identified to harbour different species of Plasmodium. Long-tailed macaques (Macaca fascicularis), in particular, are reservoirs for P. knowlesi, P. inui, P. cynomolgi, P. coatneyi and P. fieldi. A previous study conducted in Sarawak, Malaysian Borneo, however revealed that long-tailed macaques could potentially harbour novel species of Plasmodium based on sequences of small subunit ribosomal RNA and circumsporozoite genes. To further validate this finding, the mitochondrial genome and the apicoplast caseinolytic protease M genes of Plasmodium spp. were sequenced from 43 long-tailed macaque blood samples.

Results

Apart from several named species of malaria parasites, long-tailed macaques were found to be potentially infected with novel species of Plasmodium, namely one we refer to as “P. inui-like.” This group of parasites bifurcated into two monophyletic clades indicating the presence of two distinct sub-populations. Further analyses, which relied on the assumption of strict co-phylogeny between hosts and parasites, estimated a population expansion event of between 150,000 to 250,000 years before present of one of these sub-populations that preceded that of the expansion of P. knowlesi. Furthermore, both sub-populations were found to have diverged from a common ancestor of P. inui approximately 1.5 million years ago. In addition, the phylogenetic analyses also demonstrated that long-tailed macaques are new hosts for P. simiovale.

Conclusions

Malaria infections of long-tailed macaques of Sarawak, Malaysian Borneo are complex and include a novel species of Plasmodium that is phylogenetically distinct from P. inui. These macaques are new natural hosts of P. simiovale, a species previously described only in toque monkeys (Macaca sinica) in Sri Lanka. The results suggest that ecological factors could affect the evolution of malaria parasites.

Electronic supplementary material

The online version of this article (10.1186/s12862-018-1170-9) contains supplementary material, which is available to authorized users.

Phylogeny of Anophelinae using mitochondrial protein coding genes

Malaria is a vector-borne disease that is a great burden on the poorest and most marginalized communities of the tropical and subtropical world. Approximately 41 species of Anopheline mosquitoes can effectively spread species of Plasmodium parasites that cause human malaria. Proposing a natural classification for the subfamily Anophelinae has been a continuous effort, addressed using both morphology and DNA sequence data. The monophyly of the genus Anopheles, and phylogenetic placement of the genus Bironella, subgenera Kerteszia, Lophopodomyia and Stethomyia within the subfamily Anophelinae, remain in question. To understand the classification of Anophelinae, we inferred the phylogeny of all three genera (Anopheles, Bironella, Chagasia) and major subgenera by analysing the amino acid sequences of the 13 protein coding genes of 150 newly sequenced mitochondrial genomes of Anophelinae and 18 newly sequenced Culex species as outgroup taxa, supplemented with 23 mitogenomes from GenBank. Our analyses generally place genus Bironella within the genus Anopheles, which implies that the latter as it is currently defined is not monophyletic. With some inconsistencies, Bironella was placed within the major clade that includes Anopheles, Cellia, Kerteszia, Lophopodomyia, Nyssorhynchus and Stethomyia, which were found to be monophyletic groups within Anophelinae. Our findings provided robust evidence for elevating the monophyletic groupings Kerteszia, Lophopodomyia, Nyssorhynchus and Stethomyia to genus level; genus Anopheles to include subgenera Anopheles, Baimaia, Cellia and Christya; Anopheles parvus to be placed into a new genus; Nyssorhynchus to be elevated to genus level; the genus Nyssorhynchus to include subgenera Myzorhynchella and Nyssorhynchus; Anopheles atacamensis and Anopheles pictipennis to be transferred from subgenus Nyssorhynchus to subgenus Myzorhynchella; and subgenus Nyssorhynchus to encompass the remaining species of Argyritarsis and Albimanus Sections.

Phylogeny of Anophelinae using mitochondrial protein coding genes

Malaria is a vector-borne disease that is a great burden on the poorest and most marginalized communities of the tropical and subtropical world. Approximately 41 species of Anopheline mosquitoes can effectively spread species of Plasmodium parasites that cause human malaria. Proposing a natural classification for the subfamily Anophelinae has been a continuous effort, addressed using both morphology and DNA sequence data. The monophyly of the genus Anopheles, and phylogenetic placement of the genus Bironella, subgenera Kerteszia, Lophopodomyia and Stethomyia within the subfamily Anophelinae, remain in question. To understand the classification of Anophelinae, we inferred the phylogeny of all three genera (Anopheles, Bironella, Chagasia) and major subgenera by analysing the amino acid sequences of the 13 protein coding genes of 150 newly sequenced mitochondrial genomes of Anophelinae and 18 newly sequenced Culex species as outgroup taxa, supplemented with 23 mitogenomes from GenBank. Our analyses generally place genus Bironella within the genus Anopheles, which implies that the latter as it is currently defined is not monophyletic. With some inconsistencies, Bironella was placed within the major clade that includes Anopheles, Cellia, Kerteszia, Lophopodomyia, Nyssorhynchus and Stethomyia, which were found to be monophyletic groups within Anophelinae. Our findings provided robust evidence for elevating the monophyletic groupings Kerteszia, Lophopodomyia, Nyssorhynchus and Stethomyia to genus level; genus Anopheles to include subgenera Anopheles, Baimaia, Cellia and Christya; Anopheles parvus to be placed into a new genus; Nyssorhynchus to be elevated to genus level; the genus Nyssorhynchus to include subgenera Myzorhynchella and Nyssorhynchus; Anopheles atacamensis and Anopheles pictipennis to be transferred from subgenus Nyssorhynchus to subgenus Myzorhynchella; and subgenus Nyssorhynchus to encompass the remaining species of Argyritarsis and Albimanus Sections.

Complete mitochondrial genomes of Anopheles stephensi and An. dirus and comparative evolutionary mitochondriomics of 50 mosquitoes

To better understand the phylogeny and evolution of mosquitoes, the complete mitochondrial genome (mitogenome) of Anopheles stephensi and An. dirus were sequenced and annotated, and a total of 50 mosquito mitogenomes were comparatively analyzed. The complete mitogenome of An. stephensi and An. dirus is 1,5371 bp and 1,5406 bp long, respectively. The main features of the 50 mosquito mitogenomes are conservative: 13 protein-coding genes (PCGs), two ribosomal RNA genes, 22 transfer RNA genes, positive AT-skew and negative GC-skew. The gene order trnA-trnR in ancestral insects is rearranged. All tRNA genes have the typical clover leaf secondary structure but tRNA Ser . The control regions are highly variable in size. PCGs show signals of purifying selection, but evidence for positive selection in ND2, ND4 and ND6 is found. Bayesian and Maximum Likelihood phylogenetic analyses based on all PCG nucleotides produce an identical tree topology and strongly support the monophyly of subgenera Cellia, Anopheles, Keterszia and Nyssorhynchus, the sister relationship of the subgenera Nyssorhynchus and Keterszia, and Cellia and Anopheles. The most recent ancestor of the genus Anopheles and Culicini + Aedini exited ~145 Mya ago. This is the first comprehensive study of mosquito mitogenomes, which are effective for mosquito phylogeny at various taxonomic levels.

Discrimination of Neotropical Anopheles species based on molecular and wing geometric morphometric traits

Morphological similarities among closely related Anopheles species that differ in biological traits and malaria transmission represent a challenge in medical entomology; therefore, new tools are constantly tested to bring solutions. Particularly, in this work, a geometric morphometric analysis of wing geometry variation, based on morphologically and molecularly identified specimens, was applied for the discrimination of fourteen Anopheles species belonging to the Nyssorhynchus, Anopheles and Kerteszia subgenera. DNA barcodes helped to confirm species assignation and the geometric morphometric approach revealed wing form differences not only at the subgenera but also at the species level. Each subgenus presented a particular wing size trend, possibly related to the evolutionary history of these lineages. Wing shape allowed species discrimination, except for some very closely related taxa. The current findings highlight the importance of using complementary approaches involving morphological and molecular data for Anopheles species discrimination.

[Phylogenetic signal at the Cytb-SertRNA-IG1-ND1 mitochondrial region in Anopheles (Kerteszia) neivai Howard, Dyar & Knab, 1913]

INTRODUCTION

Mitochondrial DNA has proven its utility for the study of insect evolution. Genes such as cytochrome b (Cytb) and the transfer gene for serine (SertRNA) can be used to compare closely related organisms.

OBJECTIVE

The phylogenetic utility of Cytb-SertRNA-IG1-ND1 was tested for polymorphisms, and secondary structure modeling in SertRNA was done to detect possible cryptic species in Anopheles neivai.

MATERIALS AND METHODS

Specimens from Colombia, Guatemala, and the type locality in Panamá were collected and sequenced for specimen comparison based on DNA polymorphisms, and secondary structure modeling for the SertRNA gene.

RESULTS

Thirty-six sequences for A. neivai and A. pholidotus were obtained.

CONCLUSIONS

Polymorphic variants were detected in A. neivai for Cytb-SertRNA-IG1- ND1. Despite this variation in A. neivai, cryptic species could not be detected.

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 mitochondrial genomes of Culex tritaeniorhynchus and Culex pipiens pallens (Diptera: Culicidae) and comparison analysis with two other Culex species

Background

Culex tritaeniorhynchus and Culex pipiens pallens are the major vectors of the Japanese encephalitis virus and Wuchereria bancrofti, the causative agent of filariasis. The knowledge of mitochondrial genomes has been widely useful for the studies on molecular evolution, phylogenetics and population genetics.

Methods

In this study, we sequenced and annotated the mitochondrial (mt) genomes of Cx. tritaeniorhynchus and Cx. p. pallens, and performed a comparative analysis including four known mt genomes of species of the subgenus Culex (Culex). The phylogenetic relationships of Cx. tritaeniorhynchus, Cx. p. pallens and four known Culex mt genome sequences were reconstructed by maximum likelihood based on concatenated protein-coding gene sequences.

Results

Culex tritaeniorhynchus and Cx. p. pallens mt genomes are 14,844 bp and 15,617 bp long, both consists of 13 PCGs, 22 tRNAs, 2 rRNAs and 1 CR (not sequenced for Cx. tritaeniorhynchus). The initiation and termination codons of PCGs are ATN and TAA, respectively, except for COI starting with TCG, and COI and COII terminated with T. tRNAs have the typical clover-leaf secondary structures except for trnS^(AGN) that is lacking the DHU stem. 16S rRNA and 12S rRNA secondary structures were drawn for the first time for mosquito mt genomes. The control region of Cx. p. pallens mt genome is 747 bp long and with four tandem repeat structures. Phylogenetic analyses demonstrated that the mt genome of Cx. tritaeniorhynchus was significantly separated from the remaining five mt genomes of Culex spp. Culex p. pipiens, Cx. p. pallens and Cx. p. quinquefasciatus formed a monophyletic clade with Cx. p. quinquefasciatus linked in the middle of the clade, and Cx. p. pallens should have the same taxonomic level as Culex p. pipiens and Cx. p. quinquefasciatus.

Conclusions

The mt genomes of Cx. tritaeniorhynchus and Cx. p. pallens share the same gene composition and order with those of two other Culex species. Culex p. pallens of the Pipiens complex should have the same taxonomic level as Culex p. pipiens and Cx. p. quinquefasciatus investigated. We enriched the Culex mt genome data and provided a reference basis for further Culex mt genome sequencing and analyses.

Electronic supplementary material

The online version of this article (doi:10.1186/s13071-016-1694-z) contains supplementary material, which is available to authorized users.

The complete mitochondrial genome of Anopheles minimus (Diptera: Culicidae) and the phylogenetics of known Anopheles mitogenomes

Anopheles minimus is an important vector of human malaria in southern China and Southeast Asia. The phylogenetics of mosquitoes has not been well resolved, and the mitochondrial genome (mtgenome) has proven to be an important marker in the study of evolutionary biology. In this study, the complete mtgenome of An. minimus was sequenced for the first time. It is 15 395 bp long and encodes 37 genes, including 13 protein-coding genes (PCGs), 22 transfer RNAs (tRNAs), two ribosomal RNAs (rRNAs) and a non-coding region. The gene organization is consistent with those of known Anopheles mtgenomes. The mtgenome performs a clear bias in nucleotide composition with a positive AT-skew and a negative GC-skew. All 13 PCGs prefer to use the codon UUA (Leu), ATN as initiation codon but cytochrome-oxidase subunit 1 (COI) and ND5, with TCG and GTG, and TAA as termination codon, but COI, COII, COIII and ND4, all with the incomplete T. tRNAs have the typical clover-leaf structure, but tRNA(Ser(AGN)) is consistent with known Anopheles mtgenomes. The control region includes a conserved T-stretch and a (TA)n stretch, and has the highest A+T content at 93.1%. The phylogenetics of An. minimus with 18 other Anopheles species was constructed by maximum likelihood and Bayesian inference, based on concatenated PCG sequences. The subgenera, Cellia and Anopheles, and Nyssorhynchus and Kerteszia have mutually close relationships, respectively. The Punctulatus group and Leucosphyrus group of Neomyzomyia Series, and the Albitarsis group of Albitarsis Series were suggested to be monophyletic. The monophyletic status of the subgenera, Cellia, Anopheles, Nyssorhynchus and Kerteszia need to be further elucidated.

Morphogenetic characterisation, date of divergence, and evolutionary relationships of malaria vectors Anopheles cruzii and Anopheles homunculus

The mosquito species Anopheles cruzii and Anopheles homunculus are co-occurring vectors for etiological agents of malaria in southeastern Brazil, a region known to be a major epidemic spot for malaria outside Amazon region. We sought to better understand the biology of these species in order to contribute to future control efforts by (1) improving species identification, which is complicated by the fact that the females are very similar, (2) investigating genetic composition and morphological differences between the species, (3) inferring their phylogenetic histories in comparison with those of other Anophelinae, and (4) dating the evolutionary divergence of the two species. To characterise the species we used wing geometry and mitochondrial cytochrome oxidase subunit I (COI) gene as morphological and genetic markers, respectively. We also used the genes white, 28S, ITS2, Cytb, and COI in our phylogenetic and dating analyses. A comparative analysis of wing thin-plate splines revealed species-specific wing venation patterns, and the species An. cruzii showed greater morphological diversity (8.74) than An. homunculus (5.58). Concerning the COI gene, An. cruzii was more polymorphic and also showed higher haplotype diversity than An. homunculus, with many rare haplotypes that were displayed by only a few specimens. Phylogenetic analyses revealed that all tree topologies converged and showed [Anopheles bellator+An. homunculus] and [Anopheles laneanus+An. cruzii] as sister clades. Diversification within the subgenus Kerteszia occurred 2-14.2millionyears ago. The landmark data associated with wing shape were consistent with the molecular phylogeny, indicating that this character can distinguish higher level phylogenetic relationships within the Anopheles group. Despite their morphological similarities and co-occurrence, An. cruzii and An. homunculus show consistent differences. Phylogenetic analysis revealed that the species are not sister-groups but species that recently diverged within the Kerteszia group, perhaps concomitantly with the radiation of bromeliads in South America or during the Pleistocene climate oscillations.

Diversification of the Genus Anopheles and a Neotropical Clade from the Late Cretaceous

The Anopheles genus is a member of the Culicidae family and consists of approximately 460 recognized species. The genus is composed of 7 subgenera with diverse geographical distributions. Despite its huge medical importance, a consensus has not been reached on the phylogenetic relationships among Anopheles subgenera. We assembled a comprehensive dataset comprising the COI, COII and 5.8S rRNA genes and used maximum likelihood and Bayesian inference to estimate the phylogeny and divergence times of six out of the seven Anopheles subgenera. Our analysis reveals a monophyletic group composed of the three exclusively Neotropical subgenera, Stethomyia, Kerteszia and Nyssorhynchus, which began to diversify in the Late Cretaceous, at approximately 90 Ma. The inferred age of the last common ancestor of the Anopheles genus was ca. 110 Ma. The monophyly of all Anopheles subgenera was supported, although we failed to recover a significant level of statistical support for the monophyly of the Anopheles genus. The ages of the last common ancestors of the Neotropical clade and the Anopheles and Cellia subgenera were inferred to be at the Late Cretaceous (ca. 90 Ma). Our analysis failed to statistically support the monophyly of the Anopheles genus because of an unresolved polytomy between Bironella and A. squamifemur.

Developing Exon-Primed Intron-Crossing (EPIC) markers for population genetic studies in three Aedes disease vectors

Aedes aegypti, Aedes notoscriptus, and Aedes albopictus are important vectors of many arboviruses implicated in human disease such as dengue fever. Genetic markers applied across vector species can provide important information on population structure, gene flow, insecticide resistance, and taxonomy, however, robust microsatellite markers have proven difficult to develop in these species and mosquitoes generally. Here we consider the utility and transferability of 15 Ribosome protein (Rp) Exon-Primed Intron-Crossing (EPIC) markers for population genetic studies in these 3 Aedes species. Rp EPIC markers designed for Ae. aegypti also successfully amplified populations of the sister species, Ae. albopictus, as well as the distantly related species, Ae. notoscriptus. High SNP and good indel diversity in sequenced alleles plus support for amplification of the same regions across populations and species were additional benefits of these markers. These findings point to the general value of EPIC markers in mosquito population studies.

Genetic variations of ND5 gene of mtDNA in populations of Anopheles sinensis (Diptera: Culicidae) malaria vector in China

Background

Anopheles sinensis is a principal vector for Plasmodium vivax malaria in most parts of China. Understanding of genetic structure and genetic differentiation of the mosquito should contribute to the vector control and malaria elimination in China.

Methods

The present study investigated the genetic structure of An. sinensis populations using a 729 bp fragment of mtDNA ND5 among 10 populations collected from seven provinces in China.

Results

ND5 was polymorphic by single mutations within three groups of An. sinensis that were collected from 10 different geographic populations in China. Out of 140 specimens collected from 10 representative sites, 84 haplotypes and 71 variable positions were determined. The overall level of genetic differentiation of An. sinensis varied from low to moderate across China and with a F_ST range of 0.00065 – 0.341. Genealogy analysis clustered the populations of An. sinensis into three main clusters. Each cluster shared one main haplotype. Pairwise variations within populations were higher (68.68%) than among populations (31.32%) and with high fixation index (F_ST = 0.313). The results of the present study support population growth and expansion in the An. sinensis populations from China. Three clusters of An. sinensis populations were detected in this study with each displaying different proportion patterns over seven Chinese provinces. No correlation between genetic and geographic distance was detected in overall populations of An. sinensis (R² = 0.058; P = 0.301).

Conclusions

The results indicate that the ND5 gene of mtDNA is highly polymorphic in An. sinensis and has moderate genetic variability in the populations of this mosquito in China. Demographic and spatial results support evidence of expansion in An. sinensis populations.

Is the mega-diverse genus Ocyptamus (Diptera, Syrphidae) monophyletic? Evidence from molecular characters including the secondary structure of 28S rRNA

Phylogenetic relationships between two New World Syrphinae taxa (Diptera, Syrphidae), i.e. the highly diverse genus Ocyptamus and the large genus Toxomerus, were analysed based on molecular characters. The monophyly of both taxa was tested and the taxonomic status of included subgenera and species groups was examined. Toxomerus constitutes the monogeneric tribe Toxomerini with more than 140 described species, while Ocyptamus (tribe Syrphini) is a very diverse genus (over 300 spp.) with multiple recognised subgenera and species groups. Sequence data from three gene regions were used: the mitochondrial protein-coding gene cytochrome c oxidase subunit I (COI) and the nuclear 28S and 18S ribosomal RNA genes. The secondary structure of two expansion segments (D2, D3) of the ribosomal 28S RNA gene is presented for the family Syrphidae and used for the first time in a multiple sequence alignment. Molecular data were analysed using parsimony, maximum likelihood and Bayesian inference. Toxomerus was always recovered as monophyletic within Ocyptamus, and relationships to other New World taxa such as Salpingogaster (Eosalpingogaster) were well-supported. Only the subgenera and species groups of Ocyptamus were consistently recovered as monophyletic lineages, thus the apparent non-monophyly of Ocyptamus demands reclassification of this clade.

Mosquito genomics: progress and challenges

The whole-genome sequencing of mosquitoes has facilitated our understanding of fundamental biological processes at their basic molecular levels and holds potential for application to mosquito control and prevention of mosquito-borne disease transmission. Draft genome sequences are available for Anopheles gambiae, Aedes aegypti, and Culex quinquefasciatus. Collectively, these represent the major vectors of African malaria, dengue fever and yellow fever viruses, and lymphatic filariasis, respectively. Rapid advances in genome technologies have revealed detailed information on genome architecture as well as phenotype-specific transcriptomics and proteomics. These resources allow for detailed comparative analyses within and across populations as well as species. Next-generation sequencing technologies will likely promote a proliferation of genome sequences for additional mosquito species as well as for individual insects. Here we review the current status of genome research in mosquitoes and identify potential areas for further investigations.

Implications of Plasmodium parasite infected mosquitoes on an insular avifauna: the case of Socorro Island, México

Avian malaria (Plasmodium spp.) has been implicated in the decline of avian populations in the Hawaiian Islands and it is generally agreed that geographically isolated and immunologically naïve bird populations are particularly vulnerable to the pathogenic effects of invasive malaria parasites. In order to assess the potential disease risk of malaria to the avifauna of Socorro Island, México, we surveyed for Plasmodium isolates from 1,300 resident field-caught mosquitoes. Most of them were identified as Aedes (Ochlerotatus) taeniorhynchus (Wiedemann, 1821), which were abundant in the salt marshes. We also collected Culex quinquefasciatus Say, 1823 close to human dwellings. Mitochondrial ND5 and COII gene sequences of Ae. taeniorhynchus were analyzed and compared to corresponding sequences of mosquitoes of the Galápagos Islands, Latin America, and the North American mainland. Aedes lineages from Socorro Island clustered most closely with a lineage from the continental U.S. Plasmodium spp. DNA was isolated from both species of mosquitoes. From 38 positive pools, we isolated 11 distinct mitochondrial Cytb lineages of Plasmodium spp. Seven of the Plasmodium lineages represent previously documented avian infective strains while four were new lineages. Our results confirm a potential risk for the spread of avian malaria and underscore the need to monitor both the mosquito and avian populations as a necessary conservation measure to protect endangered bird species on Socorro Island.

Analysis of the evolutionary forces shaping mitochondrial genomes of a Neotropical malaria vector complex

Many vectors of human malaria belong to complexes of morphologically indistinguishable cryptic species. Here we report the analysis of the newly sequenced complete mitochondrial DNA molecules from six recognized or putative species of one such group, the Neotropical Anopheles albitarsis complex. The molecular evolution of these genomes had been driven by purifying selection, particularly strongly acting on the RNA genes. Directional mutation pressure associated with the strand-asynchronous asymmetric mtDNA replication mechanism may have shaped a pronounced DNA strand asymmetry in the nucleotide composition in these and other Anopheles species. The distribution of sequence polymorphism, coupled with the conflicting phylogenetic trees inferred from the mitochondrial DNA and from the published white gene fragment sequences, indicates that the evolution of the complex may have involved ancient mtDNA introgression. Six protein coding genes (nad5, nad4, cox3, atp6, cox1 and nad2) have high levels of sequence divergence and are likely informative for population genetics studies. Finally, the extent of the mitochondrial DNA variation within the complex supports the notion that the complex consists of a larger number of species than until recently believed.

Conservation of indole responsive odorant receptors in mosquitoes reveals an ancient olfactory trait

Aedes aegypti and Anopheles gambiae are among the best-characterized mosquito species within the Culicinae and Anophelinae mosquito clades which diverged ∼150 million years ago. Despite this evolutionary distance, the olfactory systems of these mosquitoes exhibit similar morphological and physiological adaptations. Paradoxically, mosquito odorant receptors, which lie at the heart of chemosensory signal transduction pathways, belong to a large and highly divergent gene family. We have used 2 heterologous expression systems to investigate the functional characteristics of a highly conserved subset of Ors between Ae. aegypti and An. gambiae to investigate whether protein homology correlates with odorant-induced activation. We find that these receptors share similar odorant response profiles and that indole, a common and ecologically relevant olfactory cue, elicits strong responses from these homologous receptors. The identification of other highly conserved members of this Or clade from mosquito species of varying phylogenetic relatedness supports a model in which high sensitivity to indole represents an ancient ecological adaptation that has been preserved as a result of its life cycle importance. These results provide an understanding of how similarities and disparities among homologous OR proteins relate to olfactory function, which can lead to greater insights into the design of successful strategies for the control of mosquito-borne diseases.

Anopheles (Nyssorhynchus) atacamensis (Diptera: Culicidae), a new species from Northern Chile

Anopheles (Nyssorhynchus) atacamensis, a new species in the subgenus Nyssorhynchus, is described and validated using morphological characters of the male and female adult, male genitalia and immature stages. Molecular characterization employing sequences of the ITS2 rDNA and COI mtDNA are provided. The new taxon is compared with Anopheles (Nyssorhynchus) pictipennis (Philippi) from central Chile based on morphological features of the adults, male genitalia and larva. Illustrations of the diagnostic characteristics of the male genitalia, fourth-instar larva and pupa are provided.

Phylogenetic relationships among species of Anopheles (Nyssorhynchus) (Diptera, Culicidae) based on nuclear and mitochondrial gene sequences

Phylogenetic relationships among 21 species of mosquitoes in subgenus Nyssorhynchus were inferred from the nuclear white and mitochondrial NADH dehydrogenase subunit 6 (ND6) genes. Bayesian phylogenetic methods found that none of the three Sections within Nyssorhynchus (Albimanus, Argyritarsis, Myzorhynchella) were supported in all analyses, although Myzorhynchella was found to be monophyletic at the combined genes. Within the Albimanus Section the monophyly of the Strodei Subgroup was strongly supported and within the Myzorhynchella Section Anopheles antunesi and An. lutzii formed a strongly supported monophyletic group. The epidemiologically significant Albitarsis Complex showed evidence of paraphyly (relative to An. lanei-Myzorhynchella) and discordance across gene trees, and the previously synonomized species of An. dunhami and An. goeldii were recovered as sister species. Finally, there was evidence of complexes in several species, including An. antunesi, An. deaneorum, and An. strodei.

Leveraging skewed transcript abundance by RNA-Seq to increase the genomic depth of the tree of life

Assembling the tree of life is a major goal of biology, but progress has been hindered by the difficulty and expense of obtaining the orthologous DNA required for accurate and fully resolved phylogenies. Next-generation DNA sequencing technologies promise to accelerate progress, but sequencing the genomes of hundreds of thousands of eukaryotic species remains impractical. Eukaryotic transcriptomes, which are smaller than genomes and biased toward highly expressed genes that tend to be conserved, could potentially provide a rich set of phylogenetic characters. We sampled the transcriptomes of 10 mosquito species by assembling 36-bp sequence reads into phylogenomic data matrices containing hundreds of thousands of orthologous nucleotides from hundreds of genes. Analysis of these data matrices yielded robust phylogenetic inferences, even with data matrices constructed from surprisingly few sequence reads. This approach is more efficient, data-rich, and economical than traditional PCR-based and EST-based methods and provides a scalable strategy for generating phylogenomic data matrices to infer the branches and twigs of the tree of life.

Molecular phylogenetics and biogeography of the Neocellia Series of Anopheles mosquitoes in the Oriental Region

Molecular studies of population divergence and speciation across the Oriental Region are sparse, despite the region's high biodiversity and extensive Pliocene and Pleistocene environmental change. A molecular phylogenetic study of the Neocellia Series of Anopheles mosquitoes was undertaken to identify patterns of diversification across the Oriental Region and to infer the role of Pleistocene and Pliocene climatic change. A robust phylogeny was constructed using CO2 and ND5 mitochondrial genes and ITS2 and D3 nuclear ribosomal markers. Bayesian analysis of mitochondrial genes was used to date divergence events. The repeated contraction and expansion of forest habitat resulting from Pleistocene climatic fluctuations appears to have had a substantial impact on intraspecific diversification, but has not driven speciation within this group. Primarily early to mid Pliocene speciation was detected within the Annularis Group, whereas speciation within the Maculatus and Jamesii Groups occurred during the mid and late Pliocene. Both allopatric divergence driven by late Pliocene environmental changes and ecological adaptation, involving altitudinal replacement and seasonality, are likely to have influenced speciation in the Maculatus Group.

Analysis of the phylogenetic relationship of Anopheles species, subgenus Cellia (Diptera: Culicidae) and using it to define the relationship of morphologically similar species

Studies on the relationship of various vectors and non-vectors of malaria from the evolutionary point of view are important. Use of molecular methods to define phylogeny helps to understand the interrelationship among the members of the anophelines and elucidate the ambiguity that has arisen from improper classification. It could also help to design molecular markers for species differentiation, particularly in those which pose difficulty when classified, based on morphological features. In the present study, the phylogenetic relationships among the species of the anophelines of subgenus Cellia are inferred from the mitochondrial genes COI and COII, the ribosomal RNA gene, in particular the D3 region, and Internal Transcribed Spacer 2 (ITS2) region. The molecular phylogeny obtained in this work matches with that of the classical morphological taxonomy reasonably well, and was useful in properly defining species positions and resolving the ambiguity that normally arises due to morphological taxonomy. The correct arrangement of the various anopheline taxa as per the traditional morphological character-based classification of anophelines was there when we considered the D3 region of 28S rRNA gene and ITS2 region of rDNA. However, the arrangement of the taxa did not match with that of the morphological classification in some aspects, when we considered the COI and COII region of mitochondrial DNA. It may have been due to the variable degree of the rate of evolution of the different genes within the organism. Thus, a proper selection of those particular genes that evolve at the rate that is reflected at the species differentiation level, could help to construct the correct phylogenetic relationship among the anophelines and could be used to correlate with the grouping pattern done from the morphological perspective.

Natural colonization and adaptation of a mosquito species in Galapagos and its implications for disease threats to endemic wildlife

Emerging infectious diseases of wildlife have been recognized as a major threat to global biodiversity. Endemic species on isolated oceanic islands, such as the Galápagos, are particularly at risk in the face of introduced pathogens and disease vectors. The black salt-marsh mosquito (Aedes taeniorhynchus) is the only mosquito widely distributed across the Galápagos Archipelago. Here we show that this mosquito naturally colonized the Galápagos before the arrival of man, and since then it has evolved to represent a distinct evolutionary unit and has adapted to habitats unusual for its coastal progenitor. We also present evidence that A. taeniorhynchus feeds on reptiles in Galápagos in addition to previously reported mammal and bird hosts, highlighting the important role this mosquito might play as a bridge-vector in the transmission and spread of extant and newly introduced diseases in the Galápagos Islands. These findings are particularly pertinent for West Nile virus, which can cause significant morbidity and mortality in mammals (including humans), birds, and reptiles, and which recently has spread from an introductory focus in New York to much of the North and South American mainland and could soon reach the Galápagos Islands. Unlike Hawaii, there are likely to be no highland refugia free from invading mosquito-borne diseases in Galápagos, suggesting bleak outcomes to possible future pathogen introduction events.

Population structure of Cicada barbara Stål (Hemiptera, Cicadoidea) from the Iberian Peninsula and Morocco based on mitochondrial DNA analysis

We assess the genetic history and population structure of Cicada barbara in Morocco and the Iberian Peninsula, based on analysis of the mitochondrial cytochrome b gene. The divergence between Morocco and the Iberian Peninsula populations was strongly corroborated by the molecular data, suggesting genetically isolated populations with a low level of gene flow. The Ceuta population from Spanish North Africa was more similar to the Iberian populations than the surrounding Moroccan populations, suggesting that the Strait of Gibraltar has not been acting as a strict barrier to dispersal while the Rif Mountains have. The Iberian Peninsula specimens showed a signature of demographic expansion before that which occurred in Morocco, but some of the assumptions related to the demographic parameters should be considered with caution due to the small genetic variation found. The high haplotype diversity found in Morocco implies higher demographic stability than in the Iberian Peninsula populations. These results do not, however, suggest a Moroccan origin for Iberian cicadas; but the most northwest region in Africa, such as Ceuta, might have acted as a southern refuge for Iberian cicadas during the most severe climatic conditions, from where they could expand north when climate improved. The separation of two subspecies within C. barbara (C. barbara lusitanica and C. barbara barbara) finds support with these results.

Cladistic analysis of the subgenus Anopheles (Anopheles) Meigen (Diptera: Culicidae) based on morphological characters

In the present study, we used morphological characters to estimate phylogenetic relationships among members of the subgenus Anopheles Meigen. Phylogenetic analyses were carried out for 36 species of Anopheles (Anopheles). An. (Stethomyia) kompi Edwards, An. (Lophopodomyia) gilesi (Peryassú), Bironella hollandi Taylor, An. (Nyssorhynchus) oswaldoi (Peryassú) and An. (Cellia) maculatus Theobald were employed as outgroups. One hundred one characters of the external morphology of the adult male, adult female, fourth-instar larva, and pupa were scored and analyzed under the parsimony criterion in PAUP. Phylogenetic relationships among the series and several species informal groups of Anopheles (Anopheles) were hypothesized. The results suggest that Anopheles (Anopheles) is monophyletic. Additionally, most species groups included in the analysis were demonstrated to be monophyletic.

The second internal transcribed spacer of nuclear ribosomal DNA as a tool for Latin American anopheline taxonomy - a critical review

Among the molecular markers commonly used for mosquito taxonomy, the internal transcribed spacer 2 (ITS2) of the ribosomal DNA is useful for distinguishing among closely-related species. Here we review 178 GenBank accession numbers matching ITS2 sequences of Latin American anophelines. Among those, we found 105 unique sequences corresponding to 35 species. Overall the ITS2 sequences distinguish anopheline species, however, information on intraspecific and geographic variations is scarce. Intraspecific variations ranged from 0.2% to 19% and our analysis indicates that misidentification and/or sequencing errors could be responsible for some of the high values of divergence. Research in Latin American malaria vector taxonomy profited from molecular data provided by single or few field capture mosquitoes. However we propose that caution should be taken and minimum requirements considered in the design of additional studies. Future studies in this field should consider that: (1) voucher specimens, assigned to the DNA sequences, need to be deposited in collections, (2) intraspecific variations should be thoroughly evaluated, (3) ITS2 and other molecular markers, considered as a group, will provide more reliable information, (4) biological data about vector populations are missing and should be prioritized, (5) the molecular markers are most powerful when coupled with traditional taxonomic tools.

Molecular identification and phylogeny of the Maculatus group of Anopheles mosquitoes (Diptera: Culicidae) based on nuclear and mitochondrial DNA sequences

The Maculatus group of Anopheles mosquitoes (Diptera: Culicidae) comprises eight known species, including important malaria vectors in Southeast Asia. The sequences of the second internal transcribed spacer (ITS2) and third domain (D3) of ribosomal DNA, and cytochrome oxidase subunit II (COII) of mitochondrial DNA were obtained for five species of the group from China, as An. maculatus, An. willmori, An. pseudowillmori, An. sawadwongporni and An. dravidicus. The variation within taxon is much smaller than that between taxa. A diagnostic PCR assay for distinguishing the five members was developed based on the interspecific ITS2 variation. The phylogenetic relationships for the group were estimated on the ITS2 and D3 data. The Maculatus group appears monophyletic with An. pseudowillmori at a basal position, the Sawadwongporni subgroup and the Maculatus subgroup form sister clades. Our data concludes that An. dispar and An. greeni belong to the Maculatus subgroup, and An. willmori is not closer to either of the subgroups.

Microsatellites and 16S sequences corroborate phenotypic evidence of trans-Andean variation in the parasitoid Microctonus hyperodae (Hymenoptera: Braconidae)

Eight South American geographical populations of the parasitoid Microctonus hyperodae Loan were collected in South America (Argentina, Brazil, Chile and Uruguay) and released in New Zealand for biological control of the weevil Listronotus bonariensis (Kuschel), a pest of pasture grasses and cereals. DNA sequencing (16S, COI, 28S, ITS1, beta-tubulin), RAPD, AFLP, microsatellite, SSCP and RFLP analyses were used to seek markers for discriminating between the South American populations. All of the South American populations were more homogeneous than expected. However, variation in microsatellites and 16S gene sequences corroborated morphological, allozyme and other phenotypic evidence of trans-Andes variation between the populations. The Chilean populations were the most genetically variable, while the variation present on the eastern side of the Andes mountains was a subset of that observed in Chile.

Transposable elements in mosquitoes

We describe the current state of knowledge about transposable elements (TEs) in different mosquito species. DNA-based elements (class II elements), non-LTR retrotransposons (class I elements), and MITEs (Miniature Inverted Repeat Transposable Elements) are found in the three genera, Anopheles, Aedes and Culex, whereas LTR retrotransposons (class I elements) are found only in Anopheles and Aedes. Mosquitoes were the first insects in which MITEs were reported; they have several LTR retrotransposons belonging to the Pao family, which is distinct from the Gypsy-Ty3 and Copia-Ty1 families. The number of TE copies shows huge variations between classes of TEs within a given species (from 1 to 1000), in sharp contrast to Drosophila, which shows only relatively minor differences in copy number between elements (from 1 to 100). The genomes of these insects therefore display major differences in the amount of TEs and therefore in their structure and global composition. We emphasize the need for more population genetic data about the activity of TEs, their distribution over chromosomes and their frequencies in natural populations of mosquitoes, to further the current attempts to develop a transgenic mosquito unable to transmit malaria that is intended to replace the natural populations.

Systematics and biogeographical implications of the phylogenetic relationships between members of the funestus and minimus groups of Anopheles (Diptera: Culicidae)

The Afrotropical Funestus and the Oriental-African Minimus Groups of the Myzomyia Series of Anopheles subgenus Cellia are considered distinct only because of their geographical separation. For the first time, a phylogenetic study was done on six Oriental and four Afrotropical species based on the comparison of ribosomal (ITS2, D3) and mitochondrial (COI) nucleotide sequences. Both maximum parsimony (MP) and maximum likelihood (ML) analyses revealed that the groups form a monophyletic assemblage containing four clades. The inclusion of Afrotropical An. leesoni with the Oriental species was confirmed, whereas An. rivulorum, also an Afrotropical species, was placed in a basal position relative to the African and Oriental species. The biogeography of the Afrotropical and Oriental species was examined in relation to the phylogeny and estimates of divergence time. Divergence events correspond to periods of major tectonic movement as well as periods of great aridity or humidity.

The classification of genus Anopheles (Diptera: Culicidae): a working hypothesis of phylogenetic relationships

The internal classification of genus Anopheles is updated to reflect taxonomic actions published since the classification was last reviewed in 1994. Both formal and informal taxa are included. The classification is intended to aid researchers and students who are interested in analysing species relationships, making group comparisons and testing phylogenetic hypotheses. The genus includes 444 formally named and 40 provisionally designated extant species divided between six subgenera: Anopheles, Cellia, Kerteszia, Lophopodomyia, Nyssorhynchus and Stethomyia. Subgenera Anopheles, Cellia and Nyssorhynchus are subdivided hierarchically into nested informal groups of morphologically similar species that are believed to represent monophyletic lineages based on morphological similarity. Changes to the classification include additional species, eliminated species and changes to the hierarchical organization and composition of supraspecific groups, some as a result of molecular studies.

Revisiting the role of introgression vs shared ancestral polymorphisms as key processes shaping genetic diversity in the recently separated sibling species of the Anopheles gambiae complex

The role of interspecific hybridisation in the evolution of pest species is poorly understood. In mosquito disease vectors this is of particular importance due to the evolution of insecticide resistance and the proposed release of transgenic strains that are refractory to the malaria parasite. In this study, we apply population genetic methods in a novel manner to determine whether mitochondrial DNA sequences have introgressed between the closely related African malaria vectors Anopheles gambiae and A. arabiensis. Our results suggest that speciation was geologically recent and ancestral haplotypes at the ND5 locus are retained in both species. In addition, comparing haplotype frequencies in allopatric and sympatric populations, suggest locale specific unidirectional introgression of mitochondria from A. arabiensis into A. gambiae.

Molecular evidence of speciation between island and continental populations of Anopheles (Cellia) sundaicus (Diptera: Culicidae), a principal malaria vector taxon in Southeast Asia

Anopheles sundaicus s.l. is a principal malaria vector taxon on islands and along the coastal areas of Southeast Asia. It has a wide geographical distribution and exhibits a high level of ecological and behavioral variability. Study of this taxon is crucial for understanding its biology and implementing effectise vector control measures. We compared populations of An. sundaicus from Vietnam, Thailand, and Malaysian Borneo by using two mitochondrial DNA markers: cytochrome oxidase I and cytochrome b. Genetic divergence, geographic separation, and cladistic analysis of relationships revealed the presence of two cryptic species: Anopheles sundaicus s.s. on Malaysian Borneo and An. sundaicus species A in coastal areas of Thailand and Vietnam. A polymerase chain reaction (PCR) assay was developed to easily identify these two species throughout their geographic distributions. The assay was based on sequence characterized amplified region derived from random amplified polymorphic DNA. This PCR identification method needs to be validated and adapted for the recognition of other possible species in the Sundaicus Complex.